University of North Florida
Browse the Citations
-OR-

Contact Info

Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

View Stuart Chalk's profile on LinkedIn

Heated reaction

Classification: Manifold process -> Heated reaction

Citations 505

"Colorimetric Flow Injection Analysis Of Dissolved Iron In High DOC Waters"
Water Res. 2001 Volume 35, Issue 2 Pages 363-372
Michael J. Pullin and Stephen E. Cabaniss

Abstract: An iron flow-injection analysis system has been optimized for the analysis of iron in waters high in dissolved organic carbon. The method detects either dissolved iron(II) or total dissolved iron with a detection limit of 10 nM, precision of 0.65% at 1 µM, and a dynamic range of four orders of magnitude. There are minimal interferences (<1%) from other metals at environmental concentrations. The iron(II) method measures iron(II) in the presence of excess iron(III) with less than 1% interference. When used with pre-acidified samples, the total dissolved iron method agrees well with electrothermal atomic absorption spectrometry for a variety of natural waters with a range of dissolved organic carbon (3-36 mg C/L) and iron (1-28 µM) concentrations. When used with samples at their ambient pH, the total dissolved iron method detects dissolved iron, but not colloidal iron (size fraction 0.05-0.45 µm).
Iron(2+) Lake River Spectrophotometry

"Flow Injection Extraction Spectrophotometric Determination Of Nickel Using Bis(acetylacetone)ethylenediimine"
Anal. Chim. Acta 2000 Volume 408, Issue 1-2 Pages 123-127
N. Chimpalee, D. Chimpalee, P. Keawpasert and D. Thorburn Burns

Abstract: Nickel was determined by flow injection spectrophotometry at 370 nm after extraction of nickel(II) bis(acetylacetone)ethylenediiminate chelate into chloroform. The carrier stream was deionized water and the reagent streams were phosphate buffer (pH 7.0) and 1.5% (w/v) bis(acetylacetone)ethylenediimine solutions. The reaction stream was heated to 60degC and then cooled to room temperature prior to extraction into chloroform. The sampling rate was 18 h-1. The calibration graph was linear up to 25 µg mL-1 nickel, based on injection volumes of 250 µL. The relative standard deviation (n=10) was 0.98% for 20 µg mL-1 nickel. The system has been applied to the determination of nickel in nickel-copper alloys and in synthetic electroplating solutions.
Nickel Industrial Alloy Spectrophotometry

"Determination Of Olive Oil 2-thiobarbituric Acid Reactive Substances By Parallel Flow Injection"
Anal. Chim. Acta 2000 Volume 417, Issue 1 Pages 119-124
Panayotis G. Nouros, Constantinos A. Georgiou and Moschos G. Polissiou

Abstract: A flow injection system incorporating multiple incubation coils is used for the automated determination of olive oil 2-thiobarbituric acid reactive substances (TBARS). The use of a laboratory-made parallel flow injection (PA-FI) analyzer. allows the simultaneous incubation of 10 samples. Olive oil samples are injected in a 2.0 x 10^-2 M 2-thiobarbituric acid (TBA) stream in n-propanol and then acidified by merging with a 0.10 M trichloroacetic acid stream in n-propanol. The resulting reaction mixture is diverted to an incubation coil through a stream selection valve. All incubation coils, that are immersed in a water bath at 95±1°C, are loaded in 5 min and then the flow stops for 25 min. After sample incubation, the reaction mixture is cooled by passing through an ice bath and the reaction products are measured at 532 nm. The proposed PA-FI method achieves olive oil analysis without pretreatment and minimizes solvent consumption (1.9 mL of n-propanol, 2.7 mg of TEA and 16 mg of trichloroacetic acid per analysis). Precision was found to be better than 4.6% RSD (n=10). The linear range was (0.4-10) x 10^-4 M (calculated as malondialdehyde (MDA)) and was suitable for olive oil analysis. The proposed method compares well with a manual method (relative difference 0-6.2% for the analysis of 30 olive oil samples). The analysis rate is 20 samples hr-1, while individual samples are incubated for 30 min. The PA-FI analyzer. developed allows automation of methods that require long incubation times without loss of sampling rate, overcoming the one sample at a time disadvantage of Fl.
Thiobarbituric acid Food Spectrophotometry

"Determination Of Pd(II) By Application Of An On-line Microwave Oven And Artificial Neural Networks In Flow Injection Analysis"
Anal. Chim. Acta 2000 Volume 420, Issue 1 Pages 123-131
Sun Gang, Chen Xingguo, Zhao Yunkun, Liu Mancang and Hu Zhide

Abstract: A new methodology based on the coupling of an on-line microwave oven, employed to accelerate low-rate reactions, and artificial neural networks (ANNs), applied to the modeling and optimization of a new flow injection system, is proposed. In comparison with traditional heating, a microwave can accelerate low-rate reactions more remarkably and consume less energy. ANNs with a faster back-propagation (BP) algorithm are applied to model the system. Optimum experimental conditions are generated automatically by using jointly ANNs and optimization algorithms in terms of sensitivity, sampling rate and the energy consumed by a microwave oven. The methodology is tested on a new flow injection system for the spectrophotometric determination of Pd(II) with chlorophosphonazo-p-Cl (CPA-pC) in H2SO4 media, which has first been used as chromogenic reagent in the quantitative analysis of palladium. It is shown that the methodology can improve the ability of optimization, reduce analytical time, enhance sensitivity and consume less energy in comparison with traditional methods.
Palladium(II) Geological Industrial Spectrophotometry

"Monosegmented Flow System Exploiting Multicommutation Applied To Spectrophotometric Determination Of Manganese In Soybean Digests"
Anal. Chim. Acta 1999 Volume 386, Issue 1-2 Pages 129-135
Marisa Smiderle, Boaventura F. Reis and F&aacute;bio R. P. Rocha

Abstract: A flow system combining binary sampling and monosegmented flow implemented by multicommutation was developed to improve sensitivity and sampling rate of spectrophotometric methods based on slow chemical reactions. The flow network was assembled from a set of computer controlled three-way solenoid valves. The spectrophotometric method was based on manganese (II) oxidation by periodate in phosphoric acid medium to form the permanganate anion. The reaction is relatively slow and at 47degC a sample residence time of ~5 min is necessary to attain equilibrium conditions. However, by exploiting binary sampling and monosegmented flow analysis, quantitative conversion with a sampling rate of 50 determinations per hour was achieved. The procedure was applied to Mn determination in soybean digests, showing as profitable features a linear response for sample concentrations ranging from 2.50 to 40.00 mg L-1 Mn2+, a relative standard deviation of 0.27% (n=9) for a sample solution containing 17.1 mg L-1 Mn2+, a low reagent consumption (30 mg NaIO4 per determination) and a detection limit of 1.2 mg L-1 (99.7% confidence level). Results agreed with those obtained by inductively coupled argon plasma atomic emission spectrometry at 95% confidence level.
Manganese Vegetable Sample preparation Spectrophotometry

"A Continuous Spectrophotometric System For The Discrimination/determination Of Monosaccharides And Oligosaccharides In Foods"
Anal. Chim. Acta 2000 Volume 404, Issue 1 Pages 121-129
A. C&aacute;ceres, S. C&aacute;rdenas, M. Gallego and M. Valc&aacute;rcel

Abstract: A simple, rapid method for the spectrophotometric discrimination of monosaccharides from the oligosaccharide fraction of fruit juice, jam, syrup and honey samples is proposed. The sample, in alkaline medium, is directly introduced into a flow system and passed through an activated carbon column for its decolorization; then, a volume of 200 µl is injected into the derivatising reagent stream to start the analytical reaction, which takes place at 85°C. The two fractions are discriminated on the basis of the different colors of the derivatives formed; thus, the derivatives of the monosaccharides are yellow while those of the di- and trisaccharides are violet-carmine. The two fractions are monitored at 400 and 540 nm, respectively. Sucrose gives no reaction as it is a non-reducing sugar. The proposed method allows reducing sugars contents from 0.01% to 0.80% w/v to be determined with an average relative standard deviation of 4.5% and a sampling frequency of 10 h-1. The proposed method was validated by applying it to two milk-based and sugar candidate artificial CRMs, with good correlation. The detection limits achieved (0.01% w/v for maltose, lactose and maltotriose at 540 nm) allow adulteration of fruit juices with high fructose syrup from starch at the 4% level to be detected.
Monosaccharides Oligosaccharides Maltose Lactose Maltotriose Fruit Food Food Food Spectrophotometry

"Determination Of The Pesticide Naptalam, At The Ppb Level, By FIA With Fluorimetric Detection And Online Preconcentration By Solid-phase Extraction On C-18 Modified Silica"
Anal. Chim. Acta 1999 Volume 384, Issue 2 Pages 185-191
T. Galeano D&iacute;az, M. I. Acedo Valenzuela and F. Salinas

Abstract: The paper describes a method of flow injection analysis for the determination of the pesticide Naptalam based on its hydrolysis, in an acidic medium, to 1-naphthylamine and the measurement of fluorescence due to this product in an alkaline medium. By direct injection of Naptalam in a carrier of HCl 1.0 M, subsequent heating at 100°C in the reactor and change of the pH with a flow of NH4OH 1.5 M, concentrations >3 x 10^-6 M can be analyzed. The sensitivity of the procedure is greatly increased by using online, a column (10 cm length x 0.3 cm i.d.) filled with a C-18 modified silica packing to retain a large volume of Naptalam. The injection of a very small volume of acetonitrile is enough to elute the pesticide, thus increasing the concentration in the sample zone to a great extent. The method has been successfully applied to the analysis of Naptalam, at the ppb level, in river-water samples.
Naptalam River Fluorescence

"Flow Injection Spectrophotometric Assay Of α-amylase Activity"
Anal. Chim. Acta 2000 Volume 421, Issue 1 Pages 19-25
J. F. van Staden and L. V. Mulaudzi

Abstract: A spectrophotometric flow injection method for the determination of α-amylase activity is proposed. The method is based on the analysis of the maltose obtained during the hydrolysis of amylose in the presence of α-amylase and relies on the reaction of 3,5 dinitrosalicylic-acid and maltose at boiling temperatures to form a brick red colored complex, monitored spectrophotometrically at 540 nm. The method has proved to be highly sensitive and rapid to allow analysis of 60 samples per hour. The % RSD of this method was found to be <0.5% with the working activity range of 0.005-0.06 FAU. The detection limit was found to be 0.0048 FAU. (FAU: fungal amylase unit; 1 FAU is the amount of the enzyme that hydrolyses 5.26 g of starch per hour. 1 FAU=249.85 SIGMA).
α-Amylase Sorghum Malt Wheat Malt Energy drink Spectrophotometry

"Sequential-injection Procedure For Determination Of Iodide In Pharmaceutical And Drinking Water Samples By Catalytic Reaction With Spectrophotometric Detection"
J. AOAC Int. 2001 Volume 84, Issue 2 Pages 337-341
Jos&eacute; Antonio Erustes, Rafel Forteza, and Victor Cerd&agrave;

Abstract: A novel sequential-injection system was developed for determination of iodide at very low concentrations by using a kinetic method. The method is based on the catalytic effect of iodide on the redox reaction between Ce4+ and As3+ first described by Sandell and Kolthoff. The calibration curve is constructed by measuring the decrease of Ce4+ absorbance versus iodide concentration with a delay time of 30 s. The detection limit is 1.5 µg/L, the working temperature is 45°C, and the working range is 0.002-0.5 mg/L. Reasonable agreement was obtained when the method was applied to pharmaceutical and drinking water samples. The method has a sample throughput of approximately 15/h. [Journal Article; In English; United States]
Iodide Pharmaceutical Water Spectrophotometry

"Zone Trapping In Flow Injection Analysis. Spectrophotometric Determination Of Low Levels Of Ammonium Ion In Natural Waters"
Anal. Chim. Acta 1983 Volume 151, Issue 1 Pages 39-48
F. J. Krug, B. F. Reis, M. F. Gin&eacute; and E. A. G. ZagattoJ. R. Ferreira, A. O. Jacintho

Abstract: The advantages of zone-trapping flow injection analysis over stopped-flow and intermittent-flow methods are discussed. In this method, the central portion of a processed sample is removed from the analytical path, set aside for a specified time under certain conditions, and later re-introduced into the same carrier stream. The technique was studied for a model system without chemical reaction, and then applied to the determination of NH4+ in natural waters via a modified Berthelot reaction. The main portion of the reacting sample zone is retained in a water bath at 38°C so that ~80% complete reaction is achieved without affecting the sampling rate. About 90 to 100 measurements can be made per hour; the coefficient of variation is 0.5%. Beer's law is obeyed up to 1 mg l-1, and the detection limit is 5 µg l-1. Interfering metal ions are masked by EDTA.
Ammonium Environmental Spectrophotometry

"Improved Chemiluminescence Determination Of Traces Of Cobalt(II) By Continuous-flow And Flow Injection Methods"
Anal. Chim. Acta 1983 Volume 155, Issue 1 Pages 259-262
Masaaki Yamada, Takayuki Komatsu, Shinjiro Nakahara and Shigetaka Suzuki

Abstract: Limits of detection and sampling rates in the methods of Nakahara et al. (cf. Anal. Abstr., 1983, 44, 3B147) have been improved by factors of 70 and 6, respectively, by increasing the reaction temperature to 60°C and modifying the compositions of the reagent solution In the flow injection method, the sample (10 µL) is injected into a carrier stream of dilute acid (pH 2.8), which is subsequently added to a pre-mixed reagent stream comprising 0.2 M gallic acid - 0.3 M H2O2 and 0.09 M NaOH in 3% methanol. The resulting mixture is passed through a reaction coil (1.6 m) at 60°C before measurement of the luminescence intensity (loc. cit.). Calibration graphs are rectilinear over three decades of concentration, and the limit of detection is 0.6 pg for a 10 µL sample (0.6 ng L-1 for the continuous-flow procedure); for 60 pg of Co the coefficient of variation is 1.5%. Silver enhances the signal, and CN-, Cr2O72-, CO32- and EDTA suppress the luminescence intensity, but Fe(III), Mn(II), Cr(III), Ni(II), Pb(II), Cu(II) and MnO4- do not interfere. Results obtained on standard reference materials (pond sediment and pepperbush) agree with certified values; the method has also been applied to tap-water. The sampling rate is 120 h-1.
Cobalt(II) Water Plant Environmental NIES 1 Chemiluminescence

"Comparison Of Merging Zones, Injection Of Reagent And Single Line Manifolds For Enthalpimetric Flow Injection Analysis"
Anal. Chim. Acta 1984 Volume 156, Issue 1 Pages 307-312
Celio Pasquini and Walace A. De Oliveira

Abstract: The flow enthalpimeter described can be used with any of the flow injection manifolds cited. Improved sensitivity and sampling rate are achieved by immersing the complete manifold (including the injection valve) in a constant-temperature bath and by using an open tube reactor (Schifreen et al., Anal. Abstr., 1979, 37, 3J177; 1978, 35, 1J25). The effects of flow parameters (viz, reaction-path length, flow rate and sample volume, etc.) on the over-all dispersion factor were investigated for all three manifold configurations listed for the determination of HCl by neutralization with NaOH. Limits of detection obtained with reversed-flow, single-line and merging-zone techniques were 0.07, 0.2 and 0.4 mM HCl, respectively, and sampling rates of 80 to 90 h-1 were possible.
Acids Bases Enthalpimetry

"Determination Of Penicillin-V In Fermentation Samples By Flow Injection Analysis"
Anal. Chim. Acta 1984 Volume 166, Issue 1 Pages 293-295
Ib Schneider

Abstract: The flow injection procedure involves three reagent streams, each at 0.92 mL min-1 and maintained at 45°C. Sample solution (3 µL) is injected into a penicillinase solution stream (in citrate - phosphate buffer solution of pH 6.2) and pumped through a 20-cm mixing coil to allow enzymatic hydrolysis of the penicillin to penicilloic acid. The stream is then mixed with aqueous HgCl2 and aqueous molybdoarsenic acid and passed through a 50-cm mixing coil. The 'molybdenum blue' formed is measured at 670 nm. The calibration graph was rectilinear for 100 to 1000 iu mL-1 of phenoxymethylpenicillin and sample throughput was 90 h-1. Results obtained by this procedure were compared with those obtained with an AutoAnalyzer (r = 0.954).
Phenoxymethylpenicillin Penicillin V Fermentation broth Spectrophotometry

"Spectrophotometric Determination Of Fluoride With Lanthanum/alizarin Complexone By Flow Injection Analysis"
Anal. Chim. Acta 1985 Volume 172, Issue 1 Pages 297-302
H. Wada, H. Mori and G. Nakagawa

Abstract: The sample (40 µL) is injected into a carrier stream (0.4 mL min-1) of water that is subsequently mixed with a reagent stream containing La - alizarin complexan in aqueous 70% acetone and then fed into a reaction coil (5 m x 0.5 mm) at 60°C before measurement of the absorbance at 620 nm. Calibration graphs are rectilinear for up to 1.2 mg L-1 of F- and at the 0.8 mg L-1 level the coefficient of variation is 1.12% (n = 72). Of 14 foreign ions tested only Al(III) interferes seriously. The procedure has been applied to the determination of F- in potable water. The reagent is stable for up to 3 h.
Fluoride Water Spectrophotometry

"Determination Of Total Chromium By Flow Injection Analysis"
Anal. Chim. Acta 1985 Volume 174, Issue 1 Pages 375-378
M. J. Whitaker

Abstract: The Cr(III) is oxidized to Cr(VI) with Ce(IV) and HNO3 in a reaction coil immersed in a water bath at 80°C, 1,5-diphenylcarbazide is added and the absorbance of the Cr(VI) complex is measured at 540 nm. The peak height varies rectilinearly with Cr concentration. from 0.5 to 10 mg l-1. The mean recovery for ten 5 mg L-1 standards of Cr(III) was 4.96 mg L-1 with a coefficient of variation of 0.8%; for corresponding Cr(VI) standards the corresponding data were 4.94 mg L-1 and 0.61%. Sampling rates were 40 h-1 in both instances. Peristaltic pumping was used, with dual-channel injection. Flow rates for the sample, carrier and reagent streams were 1.2 mL min-1.
Chromium, total Water Spectrophotometry

"Flow Injection Spectrophotometric Determination Of Trace Vanadium Based On Catalysis Of The Gallic Acid Bromate Reaction"
Anal. Chim. Acta 1986 Volume 183, Issue 1 Pages 269-274
Tsutomu Fukasawa, Susumu Kawakubo and Akihiro Unno

Abstract: Changes in reactant concentration, temp., pH and residence time can be used to alter the rectilinear calibration ranges and sensitivity for V. With 1.76 M BrO3- and 0.06 M gallic acid at pH 3.8, each at 0.5 mL min-1 in a flow injection system, 0.2 to 20 ng of V (20 µL injections) can be determined at 30°C. Oxidized gallic acid is detected at 380 nm. At 65°C and with 0.5 M BrO3-, 0.05 to 4 ng of V can be determined, with coefficient of variation ~5% for 0.6 ng of V. The tolerances for Al(III), Fe(III), Mo(VI) and I- are 10, 10, 50 and 200 ng, respectively, for the determination of 1 ng of V at 65°C and 2000, 200, 500 and 500 ng, respectively, at 30°.
Vanadium Spectrophotometry

"Flow Injection Configurations For Chromium Speciation With A Single Spectrophotometric Detector"
Anal. Chim. Acta 1986 Volume 186, Issue 1 Pages 139-146
J. Ruz, A. R&iacute;os, M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: Sexavalent Cr and total Cr are determined by using the reaction between Cr(VI) and 1,5-diphenylcarbazide (0.17% in 40% ethanol), with UV detection. Tervalent Cr and Cr(VI) are distinguished by using two carrier streams (0.2 M H2SO4), one of which contains 0.5 g L-1 of Ce(IV) in 0.15 M HNO3 to oxidize Cr(III) to Cr(VI) (at 42°C). Calibration graphs are rectilinear over the range 0.2 to 10.0 µg mL-1 of Cr, and the coefficient of variation is 0.8% for 1 µg of Cr. The sampling rate is 40 h-1. The most serious interferents are S2- and Hg(II); NO2-, EDTA, Cu(II) and Mn(II) only interfere in the determination of Cr(III).
Chromium(III) Chromium(VI) Water Spectrophotometry

"Spectrophotometric Flow Injection Determination Of Cellobiose Dehydrogenase Activity In Fermentation Samples With 2, 6-dichlorophenolindophenol"
Anal. Chim. Acta 1986 Volume 188, Issue 1 Pages 285-288
Kaj Andr&eacute; Holm

Abstract: Cellobiose dehydrogenase activity (range 0.25 to 1 iu mL-1) is monitored by oxidation of cellobiose to cellobionolactone. The cellobiose substrate, the 2,6-dichlorophenolindophenol(I) reagent solution in Tris buffer (pH 7.5) and the gluconolactone(II) solution in acetate buffer are mixed before addition of the enzyme. After incubation at 50°C for 20 s the absorbance is measured at 605 nm. The decrease in absorbance is a measure of enzyme activity, because I is reduced to a colorless compound. The presence of II prevents reaction of any β-glucosidase. With a sample throughput of 120 h-1, the correlation coefficient between the flow and manual procedures is 0.96 (n = 40).
Enzyme, cellobiose dehydrogenase Spectrophotometry

"Fluorimetric Determination Of Nitrate In Natural Waters With 3-amino-1,5-naphthalenedisulfonic Acid In A Flow Injection System"
Anal. Chim. Acta 1987 Volume 193, Issue 1 Pages 343-347
Shoji Motomizu, Hiroshi Mikasa and Kyoji T&ocirc;ei

Abstract: The sample (160 µL) was injected into a carrier stream containing 1 mM EDTA, 50 mM NaCl and water (pH 8.1 to 8.4) and the solution was passed through a copperized cadmium column to reduce the NO3- to NO2-. The solution was then mixed with a stream containing 2 M HCl, 1 mM EDTA and 3-aminonaphthalene-1,5-disulfonic acid (0.3 mM or 30 µM) at 90°C. The azoic acid derivative produced was determined by mixing this stream with aqueous 20% NaOH and measuring the fluorescence at 470 nm (excitation at 365 nm). The flow rate of each stream was 0.7 mL min-1. Calibration graphs were rectilinear for up to 0.2 mM NO3-; the detection limit was ~1 nM-NO3-. In the determination of 20 µM-NO3-, the coefficient of variation was 0.8% (n = 10). Most cations and anions commonly found in natural waters did not interfere. Results for river and seawater samples agreed with those obtained by ion chromatography.
Nitrate River Sea Fluorescence

"Assay For Guanase In Blood Serum By Flow Injection Analysis With Fluorescence Detection"
Anal. Chim. Acta 1987 Volume 197, Issue 1 Pages 51-56
Yohji Hayashi, Kiyoshi Zaitsu and Yosuke Ohkura

Abstract: A substrate solution (400 µL) of 35 parts of 0.1 M Tris - HCl buffer (pH 8) mixed with 1 part of 2 mM guanine in 0.01 M NaOH and 2 parts each of urate oxidase solution (0.5 iu mL-1) and catalase solution (40 iu mL-1) was incubated initially for 2 min at 37°C and then for a further 30 min following the addition of serum (10 µL). The reaction was stopped by adding 4 M HClO4 (50 µL) and the product was mixed with 2 M K2CO3 (90 µL) and centrifuged. Aliquots (20 µL) of supernatant solution were injected into the carrier stream (0.25 mL min-1), which consisted of 0.15 M NaCl and 10 mM Na2EDTA and was blended with the reagent stream (0.25 mL min-1) which contained 5 mM 3-(4-hydroxyphenyl)propionic acid in 0.1 M Tris - HCl. The blended stream passed sequentially through a 1-m mixing coil and columns containing immobilized xanthine oxidase, urate oxidase and horse-radish peroxidase, which were all immersed in a water bath at 37°C. The fluorescence of xanthine generated was measured in a 12 µL flow cell at 405 nm (excitation at 305 mm). Calibration graphs were rectilinear for up to 500 pmol of xanthine per injection with a detection limit of 0.5 pmol. The immobilized-enzyme columns were found to be stable for three months.
Enzyme, guanase Blood Serum Fluorescence

"Temperature Effects On Amperometric Detection At Nickel Oxide Electrodes In Flow Injection Systems"
Anal. Chim. Acta 1987 Volume 197, Issue 1 Pages 361-365
Ben S. Hui and Calvin O. Huber

Abstract: Measurements were made with a flow-through nickel oxide electrode at 25°C and 105°C in a flow injection system for the determination of several amines, alcohols and other organic compounds, e.g., formate, acetone and caffeine. In general, the calibration graphs were rectilinear from 0.1 µM to 0.5 mM and the detection limits were in the ng range in some instances. Sensitivity was enhanced up to tenfold at the higher temperature but with a loss in precision. The coefficient of variation were 1 to 3% (n = 7).
Acetone Alcohols Amines Caffeine Formate Amperometry Electrode Electrode

"Spectrophotometric Determination Of Total Cyanide In Waste Waters In A Flow Injection System With Gas Diffusion Separation And Preconcentration"
Anal. Chim. Acta 1987 Volume 198, Issue 1 Pages 25-36
Zhaohai Zhu and Zhaolun Fang

Abstract: The rapidity of the cited determination was improved by use of the unstable red intermediate product of the reaction of CN- with isonicotinic acid(I) and 3-methyl-1-phenyl-2-pyrazolin-5-one(II), instead of the blue final product. The pH of waste water samples was adjusted to 11.5 to 13.0 before being merged with HCl containing 1,10-phenanthroline to give a pH of 6.4 to 7.4, and reaction at 60°C in a PTFE coil. The liberated HCN diffused through a PTFE separator membrane and was absorbed by NaOH solution This pre-concentrated solution was injected into NaOH carrier, merged with chloramine T and I - II reagents downstream, and the spectrophotometric peaks were recorded at 548 nm. For a 2 mL sample and a pre-concentration. factor of 3.5, the detection limit was 6 ng mL-1. At 0.5 µg mL-1, the coefficient of variation was 1.4% (n = 22). The phenanthroline minimized the interference from most metal ions except Co(II).
Cyanide, total Waste Spectrophotometry

"Continuous-flow Determination Of Manganese In Natural Waters Containing Iron"
Anal. Chim. Acta 1987 Volume 199, Issue 1 Pages 221-226
D. J. Hydes

Abstract: Removal of interference by Fe in the formaldoxime method for Mn determination has been re-evaluated. Addition of EDTA at controlled pH after formation of the Mn - formaldoxime complex could remove interference from up to 100 µM-Fe. In the proposed procedure, the formaldoxime reagent is added at pH 9.9 to form both Mn and Fe complexes, and EDTA is added to pH 7.7 to break down the Fe complex at 37°C during 25 min before the absorbance is measured. The system could be operated at Mn concentration. up to 100 µM.
Manganese Environmental Spectrophotometry

"Continuous-flow Enzymatic Determination Of Creatinine With Improved Online Removal Of Endogeneous Ammonia"
Anal. Chim. Acta 1987 Volume 200, Issue 1 Pages 61-72
M. E. Collison and M. E. Meyerhoff

Abstract: The endogenous NH3 (1 mM) in a physiological sample (diluted with buffer of pH 9.5) is removed by an online gas pre-dialysis unit at 45°C, comprising a PTFE coil and an acid reservoir trap. The sample is passed to a flow-through enzyme reactor coil containing immobilized creatinine deiminase which converts creatinine(I) into NH3 and N-methylhydantoin. The liberated NH3 is detected with a membrane electrode. The peak potentials are directly proportional to I concentration. The method is precise and selective and I can be determined in serum and urine samples containing abnormally high levels of NH3. Determination of I in serum samples (n = 30) correlated with an existing Technicon AutoAnalyser colorimetric method (r = 0.996).
Creatinine Blood Serum Urine Electrode Electrode

"Trace Determination Of Some Heavy Metals In Waters By Flow Injection Spectrophotometry And Potentiometry"
Anal. Chim. Acta 1987 Volume 200, Issue 1 Pages 21-33
Yu. A. Zolotov, L. K. Shpigun, I. Ya. Kolotyrkina, E. A. Novikov and O. V. Bazanova

Abstract: Three automated flow injection manifolds are described for the determination of dissolved ionic or weakly associated Cu(II), Pb and Mn(II) in natural, potable and waste waters. The catalytic effect of Mn(II) on the oxidation of NN-diethylaniline by KIO4 at pH 6.86 to 7.10 and 30°C was used for the determination of 0.02 to 1.00 µg L-1 of Mn at 475 nm. The system used a three-channel manifold with reagent injection and stopped-flow. Interference by Fe(III) was eliminated by using phosphate (pH 6.86) or citrate - phosphate buffer (pH 7.10). Lead (0.7 to 100 µg l-1) was determined at 520 nm as its complex with 4-(2-pyridylazo)resorcinol (pH 9.8) after online pre-concentration. of the sample (5 to 50 ml) on a mini-column of Chelex-100 or Dowex 1-X8. Many interfering ions were masked with 10% KCN solution A potentiometric system with a Cu ion-selective electrode was used for the determination of Cu(II) (0.5 to 1000 µg l-1). Samples (50 to 500 ml), mixed with 0.5 M acetate buffer (pH 4.7), were subjected to online pre-concentration. on Chelex-100 resin.
Manganese Lead Copper Metals, heavy Sea Water Waste Potentiometry Spectrophotometry Electrode

"Micellar Catalyzed Reactions For Flow Injection Systems. Determination Of Pyridoxal"
Anal. Chim. Acta 1987 Volume 201, Issue 1 Pages 67-76
Maria A. Hern&aacute;ndez Torres, Morteza G. Khaledi and John G. Dorsey

Abstract: Aqueous micelle carrier streams gave higher sensitivities and lower limits of detection than did aqueous streams alone in the determination of pyridoxal(I) by oxidation with CN-. With 0.09 M hexadecyltrimethylammonium bromide as surfactant, the optimum response was achieved at 49°C in 0.6 M phosphate buffer (pH 6.74) at a flow rate of 1.3 mL min-1. Detection was at 355 nm and by fluorescence at 435 nm (excitation at 355 nm), the rectilinear ranges being 77 to 2000 and 0.17 to 1100 ng of I, respectively, with corresponding coefficient of variation (n = 11) of 1.76 and 3.25% for 25.5 mg L-1 of I.
Pyridoxal Fluorescence

"Flow Injection Determination Of Secondary Amines In Nonaqueous Solution With Fluorescence Detection"
Anal. Chim. Acta 1988 Volume 204, Issue 1-2 Pages 343-348
I. R. C. Whiteside and P. J. Worsfold, E. H. McKerrell

Abstract: A non-aqueous flow injection method is described for the selective determination of secondary amines, based on derivatization with 7-chloro-4-nitrobenzofurazan(I) to form fluorescent adducts. Primary amines are chemically masked online with an equimolar mixture (58 mM) of phthalaldehyde(II) and 2-mercaptoethanol(III) in ethyl acetate. Both reagents are pumped at 0.5 mL min-1. Samples (20 µL) are injected into the II - III stream and merged with the I stream for reaction at 45°C. Fluorimetric detection is at 525 nm (excitation at 480 nm). The detection limits for dibutyl-, dihexyl- and didecyl-amine were 0.08, 0.06 and 0.12 mM, respectively. The coefficient of variation for 0.34 mM dihexylamine was 1.3% (n = 5).
Amines, secondary Dibutylamine Dihexylamine Didecylamine Fluorescence

"Flow Injection Spectrophotometric Determination Of Silicate, Phosphate, And Arsenate With Online Column Separation"
Anal. Chim. Acta 1988 Volume 204, Issue 1-2 Pages 53-62
Yoshio Narusawa

Abstract: Sample solution (300 µL) was injected into the carrier stream of KCl - aqueous NH3 - EDTA (0.75 mL min-1) and passed through an anion-exchange column (15 cm x 4.6 mm) of TSK-gel SAX (5 µm). The sample was mixed with (NH4)6Mo7O24 solution and passed through a reaction coil at 95°C, then mixed with a stream (0.25 mL min-1) of ascorbic acid solution before being passed through a second coil at 95°C. The absorbance was measured at 810 nm. Calibration graphs were rectilinear from 0.01 to 0.25 mM. The relative retention times depended on the concentration. of the eluting solution The separation and simultaneous determination of SiO32-, PO43- and AsO43- was satisfactory at ~0.1 mM concentration. of each ion.
Silicate Phosphate Arsenate ion Water Ion exchange Spectrophotometry

"Continuous-flow Molecular Emission Cavity Analysis For Organic Sulfur Compounds By Alkaline Hydrolysis"
Anal. Chim. Acta 1988 Volume 204, Issue 1-2 Pages 285-293
N. Grekas and A. C. Calokerinos

Abstract: The alkaline hydrolysis (4 M NaOH) of thioacetamide, thiosemicarbazide, thiodiacetic acid and dithio-oxamide at 45°C in a continuous-flow automatic analyzer. is described. The S2- produced is removed from the solution after acidification with 4 M H3PO4 and the H2S evolved is purged with N and determined by MECA. The sampling rate is 30 h-1, and the coefficient of variation is 1 to 2.5%.
Spectrophotometry

"Determination Of Sucrose In Sugar-cane Juice And Molasses By Flow Injection Spectrophotometry"
Anal. Chim. Acta 1988 Volume 204, Issue 1-2 Pages 259-270
E. A. G. Zagatto, I. L. Mattos and A. O. Jacintho

Abstract: The diluted and filtered sugar cane juice or molasses is introduced into a flow injection analyzer. with two merging streams, producing two sample zones. One zone is fed directly to the confluence of the streams but the other first flows through a heated coil where partial and reproducible sucrose (I) inversion is achieved at controlled pH and temperature At the confluence point a buffered IO4- reagent is added to oxidize I. The consumption of IO4- is measured spectrophotometrically as a transient lowering of the iodine concentration, produced by reaction of IO4- with I-. The two zones are fed sequentially to a flow cell where two peaks are recorded. The I concentration. is proportional to the difference in peak heights. About 30 samples h-1 of sugar-cane juice can be analyzed. The coefficient of variation was 0.51% for a I concentration. of 13.66% in cane juice (n = 7). Similar precision was obtained with the modified system for molasses (20 samples h-1).
Sucrose Juice Vegetable Spectrophotometry

"Continuous-flow Potentiometric Determination Of Horseradish Peroxidase With A Fluoride-selective Electrode"
Anal. Chim. Acta 1988 Volume 208, Issue 1-2 Pages 173-181
Peter W. Alexander and Carmelita Maitra

Abstract: The horse-radish peroxidase(I)-catalyzed oxidation of 0.104 M 4-fluoroaniline in 0.16 M acetate buffer (pH 4.6) by 4.45 mM H2O2 was monitored at 45°C with a F--selective electrode in a continuous-flow system (described with diagram; flow-rate 6.8 mL min-1). The detection limit was 1 miu mL-1 of I. Interference by I inhibitors was studied at 1 µM to 1 mM levels; Cu(II), Fe(III) and Co had little effect, whereas CN- and S2- caused considerable interference. The method was applied in the determination of I in turnip extract and milk.
Enzyme, horseradish peroxidase Vegetable Milk Electrode Sample preparation Potentiometry

"The Application Of Strongly Oxidizing Agents In Flow Injection Analysis. 4. Manganese(IV) And Copper(III)"
Anal. Chim. Acta 1988 Volume 211, Issue 1-2 Pages 99-104
W. E. van der Linden, G. den Boef and W. Ozinga

Abstract: Both oxidizing reagents were prepared under batch conditions and fed to the flow injection device from a strongly alkaline stock solution. Sexavalent Te was added to keep both Cu(III) and Cu(II) in solution, as well as Mn(IV) formed after the reduction of Mn(VI). The stability of both reagents and their oxidizing ability depend on the concentration. of Te(VI) and on the alkalinity of the solution The reactions of most analytes tested with Mn(VI) required the use of a heated (65°C) coil. The flow systems used for analyzes with each reagent are presented, and applications of each are discussed. The Mn(VI) reagent is particularly useful in the determination of 0.1 to 0.01 mM monosaccharides; this is demonstrated for the determination of fructose and glucose in lemonade.
Monosaccharides Fructose Glucose Lemonade Spectrophotometry

"Determination Of Alkylamines By High Performance Liquid Chromatography With Post-column Fluorescence Derivatization"
Anal. Chim. Acta 1988 Volume 212, Issue 1-2 Pages 155-163
I. R. C. Whiteside and P. J. Worsfold, E. H. McKerrell

Abstract: For the determination of primary alkylamines in the presence of secondary alkylamines, samples were subjected to HPLC on a column (15 cm x 4.6 mm) of a styrene - divinylbenzene copolymer (5 µm) with methanol as mobile phase (0.5 mL min-1). Primary amines in the eluate were derivatized at 45°C with 58 mM phthalaldehyde and 58 mM 2-mercaptoethanol in ethyl acetate (0.5 mL min-1), the solution was mixed with ethyl acetate (0.5 mL min-1) in two knitted PTFE tubes (100 cm x 0.8 mm) and the fluorescence was measured at 431 nm in a 7 µL flow cell (excitation at 340 nm). The detection limit of decylamine was 0.18 mM. Procedures are also described for the selective determination of secondary amines [by derivatization with 7-chloro-4-nitrobenzofurazan and fluorimetry at 525 nm (excitation at 480 nm)] after masking of primary amines and for non-selective determination of primary and secondary amines. The procedures were used to analyze Synprolam 35DM surfactant, containing 98% of tertiary amines and 1% each of primary and secondary amines.
Amines, alkyl Commercial product HPLC Fluorescence

"Flow Injection Determination Of Glutathione With Amperometric Monitoring Of The Enzymatic Reaction"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 415-419
Ikuo Satoh, Shuji Arakawa and Akira Okamoto

Abstract: Gluthathione sulfydryl oxidase was immobilized (described) on to Eupergit-C (oxiran - acrylic beads; 100 to 200 µm diameter) and the preparation was packed into a plastic column (2.2 cm x 7.1 mm) which was incorporated into a flow injection system (illustrated) for indirect determination of glutathione. The flow-through amperometric detector comprised a cellulose acetate membrane-covered Pt anode and a Ag - AgCl reference electrode. Glutathione sample solution (0.2 ml) was introduced into the enzyme column at 30°C via a rotary injection valve, the carrier solution was 0.1 M potassium phosphate buffer (pH 7) containing 0.1 M KCl and the peak current arising from oxidation of H2O2 was measured. The calibration graph was rectilinear for 0.5 to 1.0 mM glutathione and the coefficient of variation (n = 10) was 2%.
Glutathione Amperometry Electrode Electrode

"Rapid Spectrophotometric Determination Of Total Phosphorus In Industrial Wastewaters By Flow Injection Analysis Including A Capillary Digestor"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 229-237
M. Aoyagi, Y. Yasumasa and A. Nishida

Abstract: Sample solution in water (as carrier) merged with oxidizing agent (K2S2O8 in H2O) before passing to a digestion unit consisting of 10 m of PTFE tubing holding 10 m of platinum wire (0.2 mm diameter) wound round an aluminum bobbin and heated to 160°C. The solution then mixed sequentially with reducing agent (aqueous 5% Na2S2O3) and color-forming reagent [aqueous malachite green (C. I. Basic Green 4) and (NH4)6Mo7O24.4H2O in ~15% H2SO4] and the absorbance was measured at 650 nm. Calibration graphs were rectilinear for up to 500 ng mL-1 of P and the determination limit was 2 ng mL-1. The coefficient of variation (n = 5) at 200 and 2 ng mL-1 were 0.3 and 6.0%, respectively. Recoveries were quantitative. The method was applied to determine P in industrial waste water and seawater; results agreed with those from the standard procedure.
Phosphorus Sea Waste Water Spectrophotometry Sample preparation

"Determination Of Trace Manganese In High-purity Titanium, Silicon And Mineral Acids By A Flow Injection Method Based On A Catalytic Reaction"
Anal. Chim. Acta 1989 Volume 217, Issue 1 Pages 23-30
Chongliang Zhang, Susumu Kawakubo and Tsutomu Fukasawa

Abstract: Sample solution (1 to 2 ml; 1.5 M in HF and 0.2 M in HCl) was subjected to ion-exchange extraction on a column of Amberlite CG-120 (H+ form, 100 to 200 mesh), with elution of the Mn with 6 M HCl. The eluate was evaporated almost to dryness, and the residue was dissolved in acetate buffer (pH 4.4). Portions (100 µL) were injected into the flow injection system where they were mixed with reagent solution [0.26 mM malachite green (C. I. Basic Green 4) - 0.01 M KIO4] before passing to a reaction coil at 50°C. The absorbance of the solution was measured at 615 nm. The calibration graph was rectilinear for up to 7 ng of Mn and the coefficient of variation (n = 5) at 3 ng of Mn was 2%. The method was successfully applied in the analysis of HF, HCl and HNO3 and of Ti metals and Si (sample prep. described).
Manganese Inorganic compound Inorganic compound Inorganic compound Metal Metal Spectrophotometry

"Flow Injection Determination Of Branched-chain L-amino-acids With Immobilized Leucine Dehydrogenase"
Anal. Chim. Acta 1989 Volume 218, Issue 1 Pages 161-166
Nobutoshi Kiba, Sachie Hori and Motohisa Furusawa

Abstract: Leucine dehydrogenase was immobilized on polystyrene Bio-Beads in a stainless-steel column (10 cm x 4 mm) and the column was incorporated into a flow system for determination of L-leucine, L-isoleucine and L-valine. A solution of 10 mM NAD+ in 1 mM Na4 EDTA was mixed with buffer solution (glycine - KCl - KOH of pH 11) before injection of the sample. The solution then passed to the enzyme reactor (thermostatted at 40°C) and the NADH produced was monitored fluorimetrically at 465 nm (excitation at 340 nm). The calibration graph was rectilinear from 5 µM to 0.5 mM isoleucine. The detection limit for L-leucine was 1 µM. The method was applied in the analysis of serum.
l-Leucine l-Isoleucine l-Valine Blood Serum Fluorescence

"Determination Of Cyanide And Thiocyanate By A Spectrophotometric Flow Injection Method"
Anal. Chim. Acta 1989 Volume 220, Issue 1 Pages 65-74
Jamal A. Sweileh

Abstract: The described two-step flow injection method involved the complexation of CN- with Ni(II) in citric acid solution followed by the determination of SCN- by oxidation with chloramine-T buffer solution (pH 5.5±0.05) to ClCN, and reaction with Na isonicotinate - Na barbiturate reagent at 65°C to form a blue complex, the absorbance of which was measured at 600 nm. To determine CN- plus SCN-, the above procedure was repeated with a Ni-free citric acid solution and the CN- concentration. was calculated by difference. The pH, temperature and Ni(II) concentration. were optimized. Calibration graphs were rectilinear up to 2.5 and 5 µg mL-1 of CN- and SCN-, respectively, and the corresponding detection limits were 0.05 and 0.08 µg mL-1. Chloride, S-, AgI, Co(II) and Ni(II) ions interfered. The procedure was applied to synthetic solution; results were in good agreement with those obtained by the ASTM method. The throughput was 10 h-1.
Thiocyanate ion Cyanide Spectrophotometry

"Flavin Mononucleotide Chemiluminescence In Cationic Micellar Media For Determination Of Chromium(III+VI) By Flow Injection"
Anal. Chim. Acta 1990 Volume 232, Issue 1 Pages 385-388
Hidehiko Ohshima, Masaaki Yamada and Shigetaka Suzuki

Abstract: In the flow injection system, sample (50 µL) in 5 mM H2O2 (3 mL min-1) was mixed with 1.4 mM flavine mononucleotide - 10 mM benzyldimethyltetradecylammonium chloride (2 mL min-1). The cationic surfactant partially suppressed the Cu(II)-induced luminescence. After mixing, the solution passed through a heating coil at 80°C and the luminescence was measured. Rectilinear log. - log. plots were obtained from 50 nM (detection limit) to 10 µM-Cr. The sampling rate was 60 h-1. At the µm level, the coefficient of variation was 3.2%. With 1 µM-Cr the presence of 0.1 mM Cu(II) caused decomposition of the H2O2 and hence an unmeasurable signal, but the presence of 10 µM-Cu(II) did not interfere. Many ions did not interfere, but the presence of 0.1 mM Fe(III), Fe(II), Co(II), SCN-, Mn(II) or Zn increased the signal due to 1 µm of each of Cr(III) and Cr(VI).
Chromium(III) Chromium(VI) Chemiluminescence

"Flow Injection System For The Fluorimetric Determination Of Fructose With An Immobilized Mannitol Dehydrogenase Reactor"
Anal. Chim. Acta 1991 Volume 243, Issue 2 Pages 183-186
Nobutoshi Kiba, Yukari Inoue and Motohisa Furusawa

Abstract: Sample solution was injected into a carrier stream of water (0.5 mL min-1), which was merged with 10, 100 or 200 µM-NADH in 0.2 M phosphate buffer (pH 7.0; 0.5 mL min-1) for reaction in a reaction column (5 cm x 4 mm) of mannitol dehydrogenase immobilized on poly(vinyl alcohol) beads (prep. described) at 40°C. The decrease in NADH was monitored fluorimetrically at 465 nm (excitation at 340 nm). Calibration graphs were rectilinear for 3 to 30, 15 to 150 or 60 to 600 µM-fructose (I) for 10, 50 and 200 µM-NADH, respectively; the detection limit was 1 µM-I for 10 µM-NADH. Seventeen carbohydrates did not interfere; D-mannitol did interfere. The sampling rate was 30 h-1. The column retained >80% of its activity after continuous use over 2 months. The method was applied in the determination of I in fruit juice, wine and cola.
Fructose Wine Fruit Soft drink Fluorescence

"Determination Of Gold In Ore By Flame Atomic Absorption Spectrometry With Flow Injection Online Sorbent Extraction Preconcentration"
Anal. Chim. Acta 1991 Volume 245, Issue 1 Pages 7-11
Shukun Xu, Lijing Sun and Zhaolun Fang

Abstract: A section of plastic Eppendorf pipette tip, measuring 0.6 and 5.0 mm i.d. at the lower and upper ends, respectively, was packed tightly (~2 cm) with Amberlite XAD-8 resin (25 to 50 mesh) (~220 µL). The column was fitted in the flow injection manifold such that adsorbed complexes were collected mainly at the narrower end and eluted from the broader to the narrower end. Samples (10 g) were heated (570°C, 30 min) in a muffle and then digested (50 min) in boiling 1:1 aqua regia (80 ml). After evaporation almost to dryness, concentrated HCl (10 ml) was added and brought to the boil. After cooling, the leachate and undissolved residue were made up to 250 mL with water. The complexes formed were adsorbed on the XAD-8 resin (7.6 mL min-1) and, after 40 s, adsorbed analyte was eluted with aqueous 95% ethanol (3.6 mL min-1) into the nebulizer and flame for determination by AAS (242.8 nm). The calibration graph was rectilinear up to 0.5 µg mL-1 and the detection limit was 2 ng mL-1 in the leachate, corresponding to 0.05 mg kg-1 in the ore. The coefficient of variation (n = 11) was 1.4% at 0.25 µg mL-1 for a single digest solution; the overall coefficient of variation was 3 to 5%. Recoveries of known amounts added to samples were 97 to 107%. The sampling rate was 60 h-1.
Gold Geological Sample preparation Spectrophotometry Sample preparation

"Flow Injection Fluorimetric Assay Of Nitrogen-containing Substrates By Online Enzymic Generation Of Ammonia"
Anal. Chim. Acta 1991 Volume 245, Issue 1 Pages 89-99
Mette Tranholm Jeppesen and Elo Harald Hansen

Abstract: In the optimization of the derivatization of NH3 with phthalaldehyde (I) and SO32- in a flow injection system, the parameters of the system were examined in a fractional factorial design at two levels and the system was then optimized with respect to significant parameters by a super-modified simplex procedure. In the optimized procedure, sample solution (30 µL), delivered at 0.5 mL min-1, was injected into the carrier stream (50 mM Na2B4O7 of pH 8.2; 0.3 mL min-1) and mixed with streams (0.3 mL min-1) of 15 mM I and 10 mM Na2SO3 in 0.1 M Na2B4O7 buffer (pH 10.5). The reaction coil (45 cm) was controlled thermostatically at 70°C, and the derivatization product was determined fluorimetrically (excitation at 365 nm; emission at 425 nm). Under these conditions the detection limit was 1 µM-NH3 and the calibration graph was rectilinear over the range 0 to 50 µM. The coefficient of variation (n = 10) was 1%. Two enzyme systems, incorporating immobilized creatinine deiminase and aspartate ammonia-lyase column reactors, were tested as model systems. The former was used to determine creatinine in serum samples.
Nitrogen Fluorescence

"Amperometric Glucose Sensor Based On Glucose Dehydrogenase Immobilized On A Graphite Electrode Modified With An NN'-bis(benzophenoxazinyl) Derivative Of Benzene-1,4-dicarboxamide [terephthalamide]"
Anal. Chim. Acta 1991 Volume 246, Issue 2 Pages 283-292
Miroslav Pol&aacute;ek, Lo Gorton, Roger Appelqvist, Gy&ouml;rgy Marko-Varga and Gillis Johansson

Abstract: Graphite rods were cut, polished, washed with water, dried at 60°C for 30 min and heated at 700°C for 90 s. The electrode was modified by application of several drops of an ethereal solution of terephthaloylbis-(5-imino-9H-benzo[a]phenoxazin-9-ylene)bis(diethylammonium chloride) and permitting the solvent to evaporate at ambient temperature Enzyme immobilization was effected by applying a buffered solution of glucose dehydrogenase - glutaraldehyde mixture. The sensor was used in a flow injection system with a buffered solution of NAD+ as carrier; the electrode potential was 0.0 mV vs. silver - AgCl. Calibration graphs were rectilinear for 3 to 500 µM-glucose. The sensor was also used to determine NADH, for which the calibration graph was rectilinear from 0.3 µM to 2 mM.
Glucose Amperometry Electrode Sensor

"Cell Permeabilization As A Tool For Measurement Of Intra-cellular Enzyme Activity In A Flow Injection System"
Anal. Chim. Acta 1991 Volume 248, Issue 2 Pages 371-378
Gert Blankenstein and Maria-Regina Kula

Abstract: Yeast cells (Candida boidinii) were incubated at 50°C for 5 min with 75 mM potassium phosphate buffer (pH 7.5) containing 0.5% digitonin, 0.5% Triton X-100 and 100 mM EDTA. The mixture was subjected to flow injection analysis with mixing with carrier solution and reagent solution (cf. Recktenwald et al. Enzyme Microb. Technol.., 1985, 7, 607). The mixture was subjected to dialysis and the NADH was detected fluorimetrically at 460 nm (excitation at 340 nm). The calibration graph was rectilinear for 0.01 to 3.0 iu mL-1 of NAD-dependent formate dehydrogenase.
Fluorescence Permittivity

"Immunological Online Detection Of Specific Proteins During Fermentation Processes"
Anal. Chim. Acta 1991 Volume 249, Issue 1 Pages 113-122
Ruth Freitag, Christel Fenge, Thomas Scheper, Karl Sch&uuml;gerl, Andreas Spreinat, Garo Antranikian and Elisabeth Fraune

Abstract: A merging zones stopped-flow flow injection system is described (with diagram) for online immunoturbidimetric determination of proteins in fermentation processes. Sample and reagent solution are injected into separate buffer streams, the streams are merged and the flow is stopped to allow incubation at 37°C. After incubation, turbidity is measured at 340 nm vs. a sample blank. For determination of monoclonal IgG, the reagent solution (0.1 mL min-1) was anti-mouse IgG (1.8 mg mL-1), the buffer solution (1 mL minmin1) was 0.01 M sodium phosphate buffer solution (pH 7.2) containing PEG 6000 (30 g l-1) and NaCl (4.5 g l-1) and the incubation time was 90 s. For assay of α-dextrin endo-1,6-α-glucosidase (I), the reagent was rabbit anti-I antibody solution, the buffer solution was the same as that for IgG, but with 40 g L-1 of PEG 6000, and the incubation time was 120 s. From 10 to 1000 iu L-1 of I and 1 to 1000 mg L-1 of IgG could be determined.
Proteins Fermentation broth Turbidimetry

"Post-column Liquid Chromatographic Method For The Determination Of Cyanide With Fluorimetric Detection"
Anal. Chim. Acta 1991 Volume 251, Issue 1-2 Pages 255-259
Keiji Gamoh*, Senya Imamichi

Abstract: Cyanide ions were separated from other ions by ion-exclusion HPLC on a Shim-pack SCR-102H column operated at 40°C with 10 mM HClO4 as mobile phase (1 mL min-1). Column eluate was mixed at 40°C with 2 mM phthalaldehyde (OPA) or naphthalenedicarboxaldehyde (NDA) and 20% ethanolic 0.5 mM Na4 EDTA in carbonate - borate buffer solution and then with 2 mM amino acid and 0.5 mM Na4 EDTA in carbonate-borate buffer. Fluorimetric detection was at 400 nm (excitation at 330 nm) for CN- - OPA derivatives or at 490 nm (excitation at 420 nm) for CN- - NDA derivatives. Use of NDA gave the best sensitivity. The calibration graph was rectilinear from 0.5 µg L-1 to 2 mg L-1 of CN-. The detection limit was ~0.1 µg l-1. The coefficient of variation (n = 10) were 1.4% at 10 µg L-1 and 3.1% at 0.5 µg l-1.
Cyanide HPLC Fluorescence

"Dehydrogenase And Ethanol Assay Based On Visible Semiconductor Laser Spectrometry"
Anal. Chim. Acta 1991 Volume 251, Issue 1-2 Pages 191-195
Totaro Imasaka, Toshiyuki Higashijima and Nobuhiko Ishibashi*

Abstract: Methods are described for the assay of dehydrogenases and the determination of NAD+ and ethanol based on visible semiconductor laser spectrometry of methylene blue. Lactate dehydrogenase (I) was assayed in serum by using a batch system. Serum (20 µL) was incubated at 37°C for 20 min with reagent solution (1 ml) containing lactic acid, NAD+, diaphorase and methylene blue in Tris buffer solution (pH 8.6) and the reaction was stopped with 1 M HCl (5 ml). Fluorescence was measured with a semiconductor laser fluorimeter. Alcohol dehydrogenase (II) and ethanol (III) were determined by using a flow system (described with diagram). II solution (0.5 µL) was injected into a merging zone (5 µL) containing diaphorase (0.6 iu), NADH (5 nmol), III (300 nmol) and 500 mM methylene blue at pH 8.7. III (1 µL) was injected into a merging zone containing II (0.6 iu), diaphorase (0.1 iu), NAD+ (5 nmol) and 500 mM methylene blue at pH 8.7. For NAD+ determination, the merging zone contained diaphorase (0.6 iu) and methylene blue (2.5 pmol) in Tris buffer solution (pH 8.7). Detection limits were 0.1 miu of II and 10 nmol of III. The calibration graph for NAD+ was rectilinear up to 40 nmol.
Ethanol Enzyme, lactate dehydrogenase Blood Serum Fluorescence Sensor

"Determination Of The Fluorescent Drugs Dipyridamole And Benzydamine In Rat Plasma By Liquid Chromatography With Peroxyoxalate Chemiluminescence Detection"
Anal. Chim. Acta 1991 Volume 251, Issue 1-2 Pages 247-253
Atsuhiko Nishitani, Yukie Tsukamoto, Susumu Kanda and Kazuhiro Imai*

Abstract: Plasma (10 µL) or, for dipyridamole (I) determination, plasma diluted 10-fold with 150 mM imidazole buffer solution (pH 6.0) was mixed with imidazole buffer solution (40 µL; as above), internal standard solution (20 µL) and acetonitrile (130 µL) and the mixture was centrifuged at 2500 g for 5 min. The internal standards were 5-(NN-dimethylaminonaphthalene)-1-sulfonyl-L-phenylalanine for I and I for benzydamine hydrochloride (II). Sample solution was injected into a flow system (described with diagram) containing a column (15 cm x 4.6 mm) of TSK ODS 8OTm (5 µm) operated at 40°C with 50 mM imidazole buffer (pH 6.0) - acetonitrile (1:1) as eluent. The eluate was mixed with 0.25 mM bis-[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl]oxalate and 12.5 mM H2O2 solution in acetonitrile - ethyl acetate (1:1) before detection of chemiluminescence. Calibration graphs were rectilinear from 2.5 to 200 nM-I and 2.5 to 100 µM-II. Detection limits were 345 pM-I and 147 nM-II.
Benzydamine Dipyridamole Plasma Rat Chemiluminescence LC

"Batchwise And Flow Injection Methods For Thermo-spectrophotometric Determination Of Acetylcholine And Choline With Tetrabromophenolphtalein Ethyl Ester"
Anal. Chim. Acta 1991 Volume 255, Issue 1 Pages 135-141
Tadao Sakai*, Yun-Hua Gao and Noriko Ohno, Nobuo Ura

Abstract: Aqueous sample solution was injected into a carrier stream of 0.3 M KH2PO4 - 0.1 M Na borate adjusted to pH 11 with 1 M NaOH, which merged with the extracting solution of tetrabromophenolphthalein ethyl ester in CH2Cl2. The extract was separated with use of a PTFE porous membrane and passed through a micro-flow cell at 45°C before its absorbance was measured at 610 nm. Sample throughout was 36 h-1 for acetylcholine (I) and choline (II). Calibration graphs were rectilinear for 0.625 to 7.5 µM-I and 1.25 to 15 µM-II. The coefficient of variation was 1.2% for 5 µM-I and 10 µM-I. The effect of amines on the determination is discussed. The determination was also carried out by batchwise method (details given).
Acetylcholine Choline Electrode Spectrophotometry Sample preparation

"Trace Enrichment Of Aluminum Ions On Immobilized Desferrioxamine"
Anal. Chim. Acta 1992 Volume 256, Issue 1 Pages 75-80
Lennart Ljunggren, Ina Altrell, Lars Risinger and Gillis Johansson*

Abstract: Desferrioxamine immobilized on porous glass was packed into a column (100 µL x 2.0 mm i.d.) and placed in the flow manifold of a flow injection system. Samples containing Al3+ were acidified with 1 mM HNO3, injected into the system and merged with NaOH to effect neutralization prior to entry into the column. The carrier was 0.1 M Na acetate buffer with 5 or 20 mM Ca lactate. The metal ions were eluted with 2 M HNO3 and the eluent was analyzed by flame or graphite-furnace AAS. There was quantitative uptake of the Al3+ at pH 5.5 to 6.0. The column temperature was kept at 50°C to allow for ligand-exchange kinetic effects. In the analysis of continuous ambulatory peritoneal dialysis solution, use of the immobilized desferrioxamine column gave improved Al detection limits, down to sub ng L-1 levels, compared with standard AAS. The column showed good stability over a 2 month period.
Aluminum Spectrophotometry Spectrophotometry

"Flow Injection Spectrophotometric Determination Of Palladium With DCS-arsenazo"
Anal. Chim. Acta 1992 Volume 256, Issue 1 Pages 113-116
Xing-Cun He*, Ya-Qi Cai, Zhi-De Hu

Abstract: The palladium sample was injected into a carrier stream of water which was merged with streams of 0.5 M H2SO4 and 0.03% 2-(2-arsenophenylazo)-7-(2,6-dichloro-4-sulfophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (I). The reaction proceeded in a 100 cm x 0.7 mm coil heated at 80°C and the absorbance was measured at 635 nm (ε 17,000). The molar ratio of Pd to I in the complex was 1:2. The calibration graph was rectilinear in the range 0 to 8.0 µg mL-1 of Pd and the detection limit was 0.05 µg mL-1. The sample throughput was 90 h-1 with 100 µL injections. In the determination of 6 µg mL-1 of Pd, the coefficient of variation of peak height was 0.57% (n = 10). I was selective in the presence of precious metals, and was used for the analysis of metallurgical samples. A flow injection spectrophotometric method for the determination of palladium involves the measurement of the absorbance of the 1:2 palladium:DCS-arsenazo complex at 635 nm (molar absorptivity 1.7 x 104 L mol-1 cm-1). The calibration graph is linear over the range 0-8.0 µg mL-1. The detection limit is 0.05 µg mL-1. The sample throughput is 90 h-1 with 100 µL sample injections. The proposed method has been applied to the determination of palladium in metallurgical samples without preliminary separation.
Palladium Metal Spectrophotometry

"Selective Determination Of Dextrins By Liquid Chromatography With Post-column Enzymic Reaction, Using Co-immobilized Enzymes"
Anal. Chim. Acta 1992 Volume 257, Issue 1 Pages 79-87
F. Ortega

Abstract: The CPG-10 support (Serva; pore diameter 51.5 nm, paricle size 37 to 74 µm) was treated with 10% (3-aminopropyl)triethoxysilane solution in toluene, the product was activated with glutaraldehyde, and glucan 1,4-α-glucosidase, glucose dehydrogenase and aldose 1-epimerase were co-immobilized on its surface from 0.1 M phosphate buffer medium (pH 6) at ambient temperature and then at 4°C. Parameters influencing enzyme behavior were optimized by means of three flow injection systems in which reactors containing the immobilized enzymes were incorporated (diagrams given). For the determination of dextrins in wort and beer, diluted samples were cleaned up by membrane filtration (0.22 µm) and passage through Sep-Pak cartridges, and portions (20 µL) were then injected into a column of Aminex HPX-42-A (at 65°C) preceded by a Micro-Guard column (Bio-Rad) for HPLC with water as mobile phase. The eluate passed via a T-piece into a flow of 3 mM NAD+ in 0.3 M phosphate buffer of pH 6 and thence through the enzyme reactor (at 40°), and the final product NADH was detected at 340 nm. Rectilinear calibration graphs based on peak area were obtained for the various dextrins, and detection limits ranged from 200 to 500 ng. The co-immobilized enzymes remained stable for 55 days when stored in 1 M NaCl at 4°.
Dextrins Beer Beer Wort HPLC Amperometry Spectrophotometry

"Improved Spectrophotometric Determination Of Lactose In Milk Using Flow Injection Analysis"
Anal. Chim. Acta 1992 Volume 258, Issue 1 Pages 141-149
Dyer Narinesingh*, Valerie A. Stoute, Gershwin Davis and Deenesh Persad, That T. Ngo

Abstract: Samples were diluted with water, treated with protein precipitating reagent (25 g of zinc acetate and 12.5 g of phosphotungstic acid dissolved in water, mixed with 20 mL of anhydrous acetic acid and diluted to 100 mL with H2O), set aside for 10 min and filtered. The filtrate was made alkaline by addition of 1 M NaOH and filtered. A 200 µL portion of the filtrate was injected into a carrier stream (0.7 mL min-1) of glycine - 0.385 M NaOH buffer of pH 12.7 (3:17) containing 0.5% methylamine hydrochloride and 0.02 M sodium sulfite and the mixture was passed through a heating coil (2.5 m long) operated at 80°C before its absorbance was measured at 540 nm. Under optimum conditions, the calibration graph was rectilinear for 1 (detection limit) to 8 mg mL-1 of lactose. Results agreed well with those obtained by LC (details given). Milk samples were analyzed spectrophotometrically for their lactose content using flow injection analysis The methodology is based on the carmine color that develops (λmax = 540 nm) when lactose reacts with alkaline methylamine (pH 12.7). Lactose concentrations as low as 0.6 mg/mL can be readily detected and up to 40 samples can be analyzed per h. Excellent correlations are obtained when the results are compared with the batch and liquid chromatography methods for lactose determination Interference from maltose, if present, should be eliminated by pretreatment with maltase.
Lactose Cow Spectrophotometry

"Chemiluminescence Flow Injection Method For The Determination Of Amino-acids Based On Schiff Base Formation In Sodium Bis-(2-ethylhexyl)sulfosuccinate Reversed Micelles"
Anal. Chim. Acta 1992 Volume 259, Issue 1 Pages 67-72
Junjiro Hayashi*, Masaaki Yamada and Toshiyuki Hobo

Abstract: The sample solution was injected into a stream of 0.1 M Na bis-(2-ethylhexyl)sulfosuccinate reversed micellar solution containing 0.1 M phenylacetaldehyde, which was then passed through a mixing coil heated at 75°C. The solution was subsequently treated with methanol (which enhances the luminescence) and with 1 mM Fe(II) and 10 mM H2O2 to oxidize the Schiff base formed. The resulting chemiluminescence was monitored with a photomultiplier tube. The rate of Schiff base formation was greatly accelerated by use of the reversed micelles, but depended on the concentration. of the reversed micellar solution and on the hydrophobicity of the amino-acid; only primary amino-acids produced chemiluminescence. The log - log calibration graph for alanine was rectilinear from 1.4 µM to 14 mM, and detection limits ranged from 1 to 130 pmol; the dynamic range was 104. A chemiluminescence flow injection method involving Schiff base formation was studied for the determination of primary amino acids. Sodium bis(2-ethylhexyl)sulfosuccinate reversed micelles effectively mediated Schiff base formation with phenylacetaldehyde and α-amino acids. The acceleration of Schiff base formation was dependent on both the water-to-surfactant ratio in the reversed micellar solution and the hydrophobocity of the amino acids. The detection limits were 1-130 pmol and the dynamic range was 104.
Amino Acids Chemiluminescence

"Determination Of Chemical Oxygen Demand In Aqueous Environmental Samples By Segmented Flow Injection Analysis"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 301-305
Li-Ching Tian* and Sao-Ming Wu

Abstract: A method is described for the determination of chemical oxygen demand (C.O.D) in aqueous environmental samples by segmented flow injection analysis. KMnO4 solution used as both an oxidant and a spectrophotometric reagent and D-glucose as a standard. When the reaction temperature is 95°C, the residence time is about 8 min and a sample throughput of 80/h can be achieved. The detection limit and relative standard deviation are 2 mg/litre and 0.7%, respectively, and the recovery is 85-95%. Chloride ion up to levels of 1500 mg/litre does not interfere with the results. C.O.D compared with those obtained using the Japanese Industrial Standard method and agreed within an error range of ±10%.
Chemical oxygen demand Environmental Spectrophotometry

"Flow Injection Spectrophotometric Determination Of Trace Cobalt With 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)aniline: Use Of The Rate-enhancing Effect Of Copper(II) On The Complex Formation Reaction Of Cobalt"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 205-211
Takeshi Yamane* and Kazuo Koshio

Abstract: In the presence of Cu(II), the otherwise slow reaction between Co and the cited reagent (I) takes place sufficiently fast at pH 4 to be used in flow injection analysis. The sample solution (98 µL), at pH 4 to 5 and containing 2 µg mL-1 of Cu(II) and 2.5 mM KIO4 (to prevent interference by Fe), is injected into the carrier solution [0.1 M acetic acid - 0.1 M Na acetate (4:1); pH 4.1] and this solution is mixed with 0.195 mM I in the same buffer in a 2.5-m reaction coil maintained at 40°C. The stream is then mixed with 1 mM EDTA in the same buffer before spectrophotometric detection at 602 nm. The addition of EDTA masks the Cu and also Ni by ligand-exchange reaction. Oxalic acid (>100 µg mL-1) interferes. The calibration graph was rectilinear up to 120 ng mL-1 of Co. The detection limit is 1 ng mL-1. The method was used to determine Co in biological materials after microwave digestion of samples with HNO3 - HCl. Results obtained on standard reference pepperbush agreed with the certified value, and reproducibility was good. A flow injection spectrophotometric method is presented for the determination of traces of cobalt utilizing its complex formation with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N- sulfopropylamino)aniline (PSAA). Copper(II) enhances the rate of the slow complex formation reaction and this provides high sensitivity in cobalt determinations in a flow system. In order to eliminate interferences from copper and nickel (which form PSAA complexes that have overlapping absorption spectra with the Co-PSAA complex), a ligand substitution reaction with EDTA was coupled online. The detection limit is 1 ng mL-1 and the relative standard deviation is 1.4% for 50 ng mL-1 cobalt. Results obtained for the anal. of the biological sample pepperbush (NIES-CRM No.1) after microwave digestion were in good agreement with the certified value of cobalt.
Cobalt NIES 1 Sample preparation Spectrophotometry

"Continuous-flow Method For The Determination Of Total Trihalomethane Formation Potential In Waters"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 335-338
Toyoaki Aoki*, Kouji Kawakami

Abstract: In the system described and illustrated, the sample stream is mixed with 10 mM NaClO in a 3-m PTFE reaction coil heated at 98°C, and the resulting solution is merged with 10% Na2SO3 solution (to remove surplus NaClO) before passage into a unit equipped with a microporous PTFE membrane and maintained at 50°C, where the trihalomethanes formed diffuse into a stream of 0.2 M NaOH. The alkaline stream is mixed with 30% nicotinamide solution in a 3-m PTFE coil at 98°C and cooled in ice before fluorescence measurement at 467 nm (excitation at 372 nm). For calibration with humic acid, the trihalomethane production was rectilinearly related to C concentration. from 1 to 5 mg l-1. The detection limit was 2.2 µg L-1 of trihalomethanes. The coefficient of variation was 4.3% for 5 mg L-1 of C as humic acid and 2.6% for 5 mg L-1 of C as albumin (n = 5). An analysis took 20 min, as compared with >26 h for the conventional Japanese method. The method was successfully applied to lake and river waters. A double-tube separation system with an inner tube of microporous poly(tetrafluoroethylene) (PTFE) and an outer tube of PTFE is proposed for the continuous determination of trihalomethane (THM) formation potential in waters. The THMs in the sample, after reaction with NaClO solution at 98°C and reduction of the residual ClO- with Na2SO3, are separated with the double-tube system at 50°C. They are then mixed with alkaline nicotinamide solution and heated at 98°C. After being cooled in an ice-bath, the reaction product is fed to a spectrofluorimeter, and the emission of fluorescence excited at 372 nm is measured at 467 nm. The response was obtained within 20 min. The detection limit (signal-to-noise ratio = 3) was 2.2 µg/L. The total THM formation potentials obtained by the present method for lake and river waters were in good agreement with those obtained by the Japanese standard batch method.
Methanes, trihalo Lake River Fluorescence

"Pyrolysis Flow Injection Analysis - Spectrophotometric Determination Of Amino-acids In Aqueous Solutions"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 23-27
J. L. Burguera and M. Burguera, M. de la Guardia and A. Salvador

Abstract: The amino-acid, in aqueous solution (20 µL), is pyrolysed (max. temperature 220°C, 265°C, 280°C or 350°C for proline, L-cysteine, DL-alanine or L-tyrosine, respectively) and the products are transferred in an Ar stream to a closed flow system for digestion with 0.05 M K2S2O8 in 0.5 M NaOH in a heated PTFE capillary containing a Pt wire. Portions of the digest are mixed with 0.5 mM Malachite green (C.I. Basic Green 4) in 2 mM (NH4)6Mo7O24 - 1.0 M H2SO4 - 30% (v/v) ethanol for the spectrophotometric determination of NO3- at 650 nm. Details of the optimized system are given. Sequential pyrolyses on the same solution are used to determine each amino-acid in the presence of the others. Responses (peak height) increase rectilinearly with amount in the range 2.5 to 16.0, 2.5 to 18.0 and 2.5 to 20.0 mg L-1 for proline (or cysteine), alanine and tyrosine, respectively, and the detection limit for each is 1.0 mg l-1. The coefficient of variation at 10 mg L-1 ranged from 1.4 to 2.4% (n = 6). Results were well correlated with those of flow injection analysis with spectrophotometric detection. A method is described for the determination of proline, cysteine, alanine and tyrosine in aqueous mixtures based on their pyrolytic conversion to nitrogen-containing compounds These compounds undergo through peroxodisulfate digestion with a heated capillary tube containing a platinum wire in a closed flow system. Subsequent mixing of aliquots of the digest and a malachite green chromogenic reagent solution in a sym. system allowed the spectrophotometric determination of nitrate at 650 nm. The method is reproducible and accurate.
Amino Acids l-Proline Cysteine Alanine Tyrosine Sample preparation Spectrophotometry

"Fully Automated System For The Continuous Monitoring Of Ammonium Ion In Fish-farming Plant Seawater By Flow Injection Analysis"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 345-349
Hideki Muraki*, Keiro Higuchi, Masanori Sasaki, Takashi Korenaga, Kyoji T&ocirc;ei

Abstract: The sample (200 µL) is introduced by an automatic injector into 3.5% NaCl solution as carrier (which has the same relative density as seawater). This stream is merged with aqueous 10% Na salicylate - 1.9% K Na tartrate, then mixed with NaClO solution (6% of active Cl) - 0.5 M NaOH (1:99) in a 2-m reaction coil at 80°C before detection at 600 nm. Calibration is rectilinear for up to 3.0 mg L-1 of ammonium-N, and at 1.0 mg L-1 the coefficient of variation was 0.35% (n = 20). Under the conditions used, common anions, Na+, Ca2+, Mg2+ and Fe3+ do not interfere. The method was applied to fish-farming seawater. An automated system for the continuous monitoring of NH4+ in fish farming plant seawater is described. The sample is introduced into a carrier stream by an automated sample injector and merged with a reagent solution containing Na salicylate and Na nitroprusside. The sample stream is then mixed with a second reagent solution containing NaClO and heated at 50°C. The absorbance of the resulting solution is monitored at 660 nm. The calibration graph was linear up to at least 3.0 mg NH4+-N/L. The relative standard deviation for 20 injections of samples containing 1.0 mg NH4+-N/L was 0.35%. The interference from Ca2+ and Mg2+ was masked with K Na tartrate. The interference due to amino acids and proteins present in fish foods and wastes was eliminated by adjusting the pH to 6-7 when the sample merged with the 1st reagent solution
Ammonia Sea Food Spectrophotometry

"Flow Injection Atomic Spectrometric Determination Of Inorganic Arsenic(III) And Arsenic(V) Species By Use Of An Aluminum-column Arsine Generator And Cold-trapping Arsine Collection"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 105-113
M. Burguera, J. L. Burguera and M. R. Brunetto, M. de la Guardia and A. Salvador

Abstract: The sample is injected into water as carrier and the solution (with or without introduction of 10% KI solution to reduce As(V)) is mixed with 5 M NaOH before passage through an electrically heated Pyrex column containing a rolled foil of metallic Al (~1 g) to reduce As(III) to AsH3. The AsH3 passes to a gas - liquid separator and is collected for 3 min in a liquid-N-cooled trap. The trap is then placed in hot water, and He is used to sweep the AsH3 into a fused-silica cell above an air - acetylene flame for AAS measurement at 193.7 nm. Analysis for As(III) and total As takes ~10 min. Optimized operating conditions are given. Interference in the determination of 1 ng of As(III) was caused by >10 ng of Ni, Be, Cr(III), Ag, Pb, Cu(II), Sn, Zr, or Fe(III). The detection limit was 0.25 µg L-1 of As(III) or As(V). The method was successfully applied to water samples from a trout fishery. A flow injection system is described for the selective determination of arsenic(III) and arsenic(V) (0.05-20 ng) in a 100 µL sample volume by hydride generation and atomic absorption spectrometry. An elec. heated aluminum column was used to generate the arsine in an alkaline medium. Recoveries averaged 97-99% for arsenic(III) and 95-98% for arsenic(V) with relative standard deviations of less than 4.3% in each instance. The detection limit was 0.25 µg L-1 (25 pg) of arsenic in both instances. This method was relatively free from interferences and was applied successfully to the determination of arsenic(III) and arsenic(V) in trout fishery water samples. The data obtained were compared with those produced by a hydride generation-cold trapping atomic absorption spectrometric detection method, using sodium tetrahydroborate(III) in hydrochloric acid. The results obtained by both methods were in close agreement, within 96-102%.
Arsenic(3+) Arsenic(5+) Arsenic, inorganic Water Spectrophotometry Spectrophotometry

"Flow Injection Determination Of Subnanogram Amounts Of Manganese By Catalysis Of The Oxidative Coupling Of NN-dimethyl-p-phenylenediamine With M-phenylenediamine"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 183-188
Shigenori Nakano*, Masahiro Nozawa and Maki Yanagawa, Takuji Kawashima

Abstract: The sample solution (183 µL) is injected into a carrier stream of HCl (1 mM or 0.1M), which is merged with, first, 0.5 M H2O2 and then a pre-merged stream of (a) 6 mM NN-dimethyl-p-phenylenediamine - 0.8 mM tiron - 10 mM L-cysteine and (b) 3 mM m-phenylenediamine - 8 mM triethylenetetramine - 0.4 M NH3; each of the four solution is pumped at 0.8 mL min-1. The resulting solution is passed through a reaction coil (8 m) at 35°C and the increase in absorbance over a reagent blank is measured at 650 nm vs. air. The development of these optimum conditions is described. The calibration graph is rectilinear for 0.05 to 1.0 ng mL-1 of Mn(II), the detection limit is 10 pg mL-1, sample throughput is 25 h-1 and the coefficient of variation at 0.3 ng mL-1 was 1.5% (n = 10). Few foreign ions interfered seriously; Fe(III) was masked by the L-cysteine. The method was successfully applied to water samples pre-diluted 20 to 500-fold with 0.1 M HCl; results on tap-, river and lake water are tabulated. A spectrophotometric flow injection method was developed for the determination of subnanogram amounts of manganese(II) based on its catalytic effect on the oxidative coupling of N,N-dimethyl-p-phenylenediamine with m-phenylenediamine in the presence of hydrogen peroxide. The catalytic activity was greatly enhanced by the presence of triethylenetetramine and 1,2-dihydroxybenzene-3,5-disulfonate together. The proposed method allows the determination of as little as 50 pg mL-1 of manganese(II) with relative standard deviations below 3% at a rate of 25 samples h-1. The method can be applied to the determination of manganese in natural waters.
Manganese Lake River Water Spectrophotometry

"Spectrofluorimetric Determination Of Cyanide And Thiocyanate Based On A Modified Koenig Reaction In A Flow Injection System"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 281-286
Akira Tanaka*, Kazuhiro Deguchi and Toshio Deguchi

Abstract: The sample solution is injected into a stream of 0.1 M NaOH, and this solution is mixed sequentially with 0.5 M H3PO4, 0.2% chloramine T solution and, in a 1-m coil heated at 60°C, with a solution containing 1% of isonicotinic acid, 2% of barbituric acid and 1.2% of NaOH. The resulting solution is cooled at 0°C before measurement of the fluorescence at 620 nm (excitation at 605 nm). The range of rectilinear calibration is 0 to 50 µM for CN- and 0 to 40 µM for SCN-; the detection limit is 30 nM. The coefficient of variation is 0.95% (n = 10) for 1 µM-CN-, and sample throughput is 30 h-1. Cyanide and thiocyanate were determined spectrofluorimetrically by the isonicotinic acid-barbituric acid (modified Koenig) reaction method. The resulting solution was excited at 605 nm and the fluorescence was measured at 620 nm. The intermediate was also fluorescent; the excitation and emission wavelengths were 527 nm and 556 nm. The flow injection procedure has a linear calibration range of 0-50 µM cyanide (or 40 µM thiocyanate), detection limits of 30 nM for both anions and a sample throughput of 30 h-1. The relative standard deviation is 0.95% for ten determinations of 1 µM cyanide.
Cyanide Thiocyanate ion Fluorescence

"Sensitive Flow Injection Technique For The Determination Of Dissolved Organic Carbon In Natural And Waste Waters"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 287-294
R. T. Edwards, I. D. McKelvie*, P. C. Ferrett, B. T. Hart and J. B. Bapat, K. Koshy

Abstract: The sample was injected into water as carrier and treated with 4.2% K2S2O8 solution in aqueous 3.6% NaBH4.10H2O. This mixture was passed through a PTFE coil (4 m x 0.5 mm) wound round a Gelman Clemco 9002 germicidal tube (40 W) for oxidation of the dissolved organic C, and de-bubbled before the introduction of 1 M H2SO4. The stream was then passed through a knotted PTFE coil (70 cm x 0.3 mm) at 95°C to liberate CO2, which, in a gas diffuser, was absorbed in a stream (pH 9.75) of 0.5 mL of methanolic 1% phenolphthalein and 1.5 mL of 0.25 M Na2CO3 - 0.25 M NaHCO3 buffer diluted with water to 1 L. The final solution was de-bubbled before absorbance measurement at 552 nm. Under optimized conditions the detection limit was 0.1 mg L-1 of C and the rectilinear calibration range extended up to 2 mg L-1; slight modification of the manifold extended the upper limit to 80 mg L-1. Recoveries of C from various organic compounds were essentially quantitative. The method was applied to river and estuarine water and to sewage treatment effluent. A flow injection method for the determination of dissolved organic C (DOC) in natural water and wastewater is based on inline UV photooxidation of DOC to CO2, with spectrophotometric detection. The method is rapid (~45 samples/h), has a linear response of 0.1-2.0 mg/L and a detection limit of ~0.1 mg/L. Minor modifications in the manifold can extend the linear response range to 80 mg/L with a slight increase in the detection limit, making the technique well-suited for the determination of DOC in natural water and wastewater.
Carbon, organic, dissolved Estuarine River Water Spectrophotometry

"Micro-distillation Unit For Use In Continuous-flow Analysers. Its Construction And Use In Determination Of Ammonia And Nitrate In Soils"
Anal. Chim. Acta 1992 Volume 266, Issue 1 Pages 107-112
S. McLeod*

Abstract: The unit described and illustrated is constructed from stainless steel and fits into an Al heating block; two such stills have been incorporated into parallel continuous-flow systems for the determination of NO3- plus NH4+ and of NH4+ alone in 2 M KCl extracts of soil by the indophenol reaction. In the former system, the extract is mixed with Ti2(SO4)3 as reductant before the distillation. Optimized conditions for the analyzes were established. The coefficient of variation for standards run for every 30 samples were 5%. The calibration graph for NH4+-N was rectilinear up to 10 mg l-1.
Ammonia Nitrate Environmental Sample preparation Spectrophotometry

"Flow Injection Determination Of Glucose In Serum With An Immobilized Pyranose Oxidase Reactor"
Anal. Chim. Acta 1992 Volume 269, Issue 2 Pages 187-191
Nobutoshi Kiba*, Fumito Ueda and Motohisa Furusawa, Takeshi Yamane

Abstract: Pyranose oxidase (I) or glucose oxidase (II) were immobilized on controlled-pore glass beads and packed into a stainless-steel column (5 cm x 4 mm) by the slurry-packing method. Glutaraldehyde solution (2%) in 0.1 M phosphate buffer (pH 7.0) was pumped through the column for 2 h at 0.2 mol min-1 and the column was washed with water. Enzyme solution (1000 iu of I or II in 0.05 M phosphate buffer (pH 7.0) was circulated through the column for 3 h at 0.2 mL min-1. Serum samples (10 µL) were injected into the carrier stream of the flow injection system (diagram given) and the H2O2 produced in the reactor at 40°C was detected by measuring the chemiluminescence emitted on mixing with luminol and K3Fe(CN)6. The calibration graph was rectilinear from 0.2 to 500 and 0.5 to 1000 µM of glucose for immobilized I and II, respectively; the corresponding detection limits were 0.05 and 0.1 µM.
Glucose Blood Serum Chemiluminescence

"Flow Injection Determination Of 1,5-anhydroglucitol In Serum With An Immobilized Pyranose Oxidase Reactor And Chemiluminescence Detection"
Anal. Chim. Acta 1993 Volume 271, Issue 1 Pages 47-51
Nobutoshi Kiba*, Fumito Ueda, Kazuya Saegusa, Yuusuke Toto and Motohisa Furusawa, Takeshi Yamane

Abstract: A stainless-steel enzyme reactor column (5 cm x 4 mm) containing pyranose oxidase bonded via glutaraldehyde onto aminopropyl-bonded controlled-pore glass (200 to 400 mesh; pore diameter 59 nm) was used at 50°C with a pre-column (4 cm x 4 mm) of TSKgel SAX anion-exchange resin (10 µm; Cl- form) for sample cleanup and a flow stream of 0.1 M NaH2PO4 - 0.05 M citric acid (pH 4.5). Post-column reaction with 0.7 mM luminol and 0.2 M K3Fe(CN)6 in a 0.3 M carbonate buffer (pH 10.5) was followed by luminescence detection of H2O2. The rectilinear calibration range was 0.4 µM to 0.2 mM 1,5-anhydroglucitol (I) with a detection limit of 0.2 µM. Human serum was analyzed and recoveries of I were 97 to 104% with coefficient of variation of 2.0% within-day or 2.4% between-day for 144 µM-I.
1,5-Anhydroglucitol Blood Serum Chemiluminescence

"Simultaneous Determination Of Sucrose And Reducing Sugars Using Indirect Flow Injection Biamperometry"
Anal. Chim. Acta 1993 Volume 271, Issue 2 Pages 239-246
Jacek Michawski and Anatol Koj, Marek Trojanowicz* and Bogdan Szostek, Elias A. G. Zagatto

Abstract: The cited method used a hexacyanoferrate(III) - hexacyanoferrate(II) indicating system. The flow injection system consisted of PTFE heating coils (0.7 mm), immersed in boiling water, and two injection valves. Two 150 µL portions of the sample were injected via the two valves with a time delay of 30 s. The first sample reacted with hexacyanoferrate(III); the second sample was hydrolyzed and then reacted with hexacyanoferrate(III). The resulting hexacyanoferrate(II) was detected. Changes in concentration. were monitored amperometrically with Pt wire electrodes polarized at 200 mV. Sucrose and glucose were determined with a sampling rate of 40 h-1. The method was applied to samples from white beet juice and syrups from stages of sugar production.
Sucrose Sugars, reducing Food Juice Biamperometry Electrode

"Liquid Chromatographic Determination Of Non-volatile Nitrosamines By Post-column Redox Reactions And Voltammetric Detection At Solid Electrodes. Study Of A Flow Reactor System Based On Cerium(IV) Reagent"
Anal. Chim. Acta 1993 Volume 273, Issue 1-2 Pages 457-467
G. Favaro, G. A. Sacchetto*, P. Pastore and M. Fiorani

Abstract: Nitrite solution (30 µL) was injected into a carrier stream (0.5 ml/min) that then merged with a reagent stream of Ce(IV) solution in 0.5 M H2SO4 (0.5 ml/min) and passed through a 25-cm-long single-bead string reactor constructed from PTFE tubing (0.5 mm i.d.) containing 0.25-mm diameter glass beads followed by a three-dimensionally knitted PTFE delay tube (3 m x 0.5 mm), both enclosed in a thermostatically controlled chamber. The solution was passed via a tightly coiled water-cooled PTFE tube (1 m x 0.5 mm) to a detector comprising a 3 µL thin-layer rectangular-channel flow cell containing an Ag/AgCl/3 M NaCl reference electrode and two flat Au-disc working electrodes for the mono- or bi-amperometric determination at 1.4 V or a difference of 0.3 V, respectively, of the Ce(III) produced by the reduction of Ce(IV) by the nitrite. When the post-column reactor was used to determine nitrite in a carrier stream of aqueous 30% acetonitrile with reactor and delay coil temperature of 70°C the response was rectilinear from 1 to 10 µM-nitrite and the detection limit was 50 nM. It was shown that the presence of the reactor and delay tube had little effect on the standard deviation of the detected peaks and gave a more nearly Gaussian peak shape. The results showed that the system should be suitable for use in the LC determination of nitrosamines.
Nitrite Nitrosamines Voltammetry HPLC

"Continuous-flow Spectrophotometric Determination Of Amino-acids With 1,2-naphthaquinone-4-sulfonate Reagent"
Anal. Chim. Acta 1993 Volume 283, Issue 1 Pages 414-420
J. Saurina and S. Hern&aacute;ndez-Cassuo*

Abstract: Streams of 0.1 M Na2CO3/0.075 M NaOH buffer (pH 10) and 1 mM 1,2-naphthaquinone-4-sulfonic acid in 0.1 M HCl were pre-merged and mixed before merging with the sample stream. The resulting solution was passed through a PTFE reaction coil maintained at 70°C to a spectrophotometric detector. Spectral data in the range 290-590 nm were collected and processed by computer. For phenylaniline as model amino-acid, with measurement at 470 nm, response was linear up to 0.15 mM and the detection limit was 2 µM; the RSD at 50 µM was 2.5% (n = 15). Forty samples could be analyzed in 1 h. Measurements on 19 amino-acids (1 mM) at four pH values in the range 8-12 were subjected to principal component analysis and cluster analysis, which allowed a systematic classification of the reaction products; determination of certain amino-acids (e.g., lysine, proline and cysteine) without chromatographic separation should thus be possible.
Amino Acids Lysine l-Proline Cysteine Spectrophotometry

"Kinetic Flow Injection Spectrofluorimetric Method For The Determination Of Fluoride"
Anal. Chim. Acta 1993 Volume 283, Issue 1 Pages 489-493
V. Marco, F. Carrillo, C. P&eacute;rez-Conde and C. C&aacute;mara*

Abstract: The method was based on the ability of trace fluoride to increase the rate of formation of the Al/Eriochrome Red B (Mordant Red 7) complex. The sample (100 µL) containing up to 4 mg/l of fluoride was injected into a carrier stream containing 0.5 mg/l of Al (as the nitrate). This solution was mixed with a stream of 1.5 M hexamine buffer of pH 6 in a reaction coil and then with a stream of ethanolic 0.01% Eriochrome Red B in a further reaction coil maintained at 70°C. The resulting solution was passed through a cooling coil at 4°C before measurement of the fluorescence at 595 nm (excitation at 470 nm). The method showed good selectivity, but 1 mg/l of Fe(III) and 10 µM-phosphate interfered. Response was linear for 1 µM-20 mM fluoride and the detection limit was 10 ng/ml. The RSD at 50 and 100 µM was 7% and 4%, respectively (n = 10). Twenty samples could be analyzed in 1 h and the method was suitable for automation. The method was used to analyze tap and mineral waters; results were in fair agreement with those obtained by using a fluoride-selective electrode.
Fluoride Water Mineral Fluorescence

"Integrated Reduction Method For The Determination Of Urea As Ammonia In Fresh Water Samples"
Anal. Chim. Acta 1993 Volume 284, Issue 2 Pages 249-255
Andre Schmitt, Louise Buttle and Roger Uglow, Kathleen Williams and Stephen Haswell*

Abstract: A flow injection system for the online microwave preparation of water samples with colorimetric determination of urea as ammonia is described. Samples (10 ml) were mixed with 1 mL of reducing agent (20 mL of 96% H2SO4 containing 13.4 g of K2SO4 and 0.2 g of HgSO4, diluted to 100 mL with H2O) and portions (0.8 ml) were injected into a stream (4 ml/min) of water and carried to a 30 m reaction coil mounted in a microwave oven operated at 485 W, where urea was reduced to ammonium ions. After passage through a 7 m cooling coil, the samples were mixed with a stream (1 ml/min) of 1.5 M NaOH in a 12 cm mixing coil and the ammonia produced passed through a gas diffusion cell with a PTFE membrane, causing a pH change in an indicator stream (1 ml/min) of bromothymol blue (0.3 g/l) for detection at 635 nm. The calibration graph was linear from 5-45 µM-urea and the RSD (n = 10) for 40 µM-urea was 3.53%; the detection limit was 2.4 µM. The recoveries were 101% and 95% for 40 and 20 µM-urea, respectively. The sample throughput time was 14 min.
Urea Ammonia Environmental Spectrophotometry

"Determination Of Paraquat By Flow Injection Spectrophotometry"
Anal. Chim. Acta 1993 Volume 284, Issue 2 Pages 275-279
Archana Jain, Krishna K. Verma and Alan Townshend*

Abstract: The cited method is based on the reduction of paraquat (I) to a blue radical cation by dehydroascorbic acid (produced by oxidizing ascorbic acid with potassium iodate). Samples (75 µL) were injected into a stream (1.1 ml/min) of water which merged with streams of 1 M NaOH and of 15 mM ascorbic acid containing 0.5 mM potassium iodate and 0.1% EDTA (0.3 and 0.6 ml/min, respectively) which had been pre-mixed in a 50 cm mixing coil. The merged streams then passed through a reaction coil (75 cm x 0.5 mm i.d.) maintained at 60°C, to a spectrophotometer where the absorbance was measured at 600 nm. The calibration graph was linear from 0.1-100 µg/ml of I and the detection limit was 20 ng/ml; the RSD (n = 6) were 1-2.5% (for 0.1-60 µg/ml of I). A large number of tested compounds (anions, metal ions and other pesticides) did not interfere; interference by diquat was masked with NaOH. The method was applied to potable water.
Paraquat Endothall sodium Water Water Spectrophotometry

"Dispersion Behaviour Of Chromogenic Reagents In A Microwave Field In A Flow System. 1. Application To The Spectrophotometric Flow Injection Determination Of Palladium And Rhodium"
Anal. Chim. Acta 1994 Volume 292, Issue 1 Pages 191-199
Yanjun Xu, Xingguo Chen and Zhide Hu*

Abstract: A flow injection study was made of the influence of microwave heating on the reactions of Pd(II), Rh(III), Ru(III), Os(IV), Ir(IV) and Pt(IV) with 4-(5-chlor-2-pyridylazo)-1,3-diaminobenzene (5-Cl-PADAB) in acetate buffer medium of pH 4 or 5. Pt(IV) did not react under any conditions but Pd(II) reacted rapidly at room temperature The remaining metals underwent reactions with 5-Cl-PADAB only when subjected to microwave heating. Based on the findings a method was developed for the simultaneous determination of Pd(II) and Rh(II). Sample (392.4 µL) and 127.5 µL of ethanolic 1.61 mM 5-Cl-PADAB were injected into acetate carrier solution (pH 4; flow rate 1.78 ml/min) and after reaction at room temperature the absorbance of the Pd-5-Cl-PADAB complex was measured at 555 nm. Then a second determination was carried out under identical conditions but with the addition of microwave heating and the absorbance was measured as before. The absorbance of the Rh-5-Cl-PADAB complex was obtained from the difference in the two absorbance measurements. Beer`s law was obeyed for 2-10 µg/ml of each metal. Results for various mixtures of Pd(II) and Rh(III) gave relative errors of -6 to +6.7% for Rh and -4.2 to +5% for Pd.
Palladium Rhodium Spectrophotometry

"Turbidimetric Determination Of Sulfate In Waters Employing Flow Injection And Lead Sulfate Formation"
Anal. Chim. Acta 1995 Volume 300, Issue 1-3 Pages 149-153
Ricardo Erthal Santelli*, Paulo Roberto Salgado Lopes, Regina C&eacute;lia Leme Santelli and Angela De Luca Rebello Wagener

Abstract: A 1.3 mL water sample was injected into a carrier stream of 1 mM HNO3 in ethanol/H2O (1:1) at a flow rate of 0.92 ml/min and the mixture was merged with a reagent solution (0.17 ml/min) comprising 1.9% lead nitrate and 1% poly(vinyl alcohol) in ethanol/H2O (1:1). An auxiliary stream (0.03 ml/min) containing 100 µg/ml of sulfate was merged with the sample plug before it entered a 100 cm x 0.5 mm i.d. precipitation coil at 61°C. After reaction, the absorbance was measured at 410 nm. Interference from chloride was eliminated by maintaining the coil at >55°C. The calibration graph was linear in the range 2-20 µg/ml of sulfate, the detection limit was 0.3 µg/ml and the RSD for 2 µg/ml of sulfate was 3% (n = 11). The analytical throughput was 35 samples/h. The method was applied to the determination of sulfate in fresh and saline waters.
Sulfate Environmental Sea Turbidimetry

"Determination Of Trace Aluminum In Natural Waters By Flow Injection Analysis With Fluorescent Detection Of The Lumogallion Complex"
Anal. Chim. Acta 1995 Volume 303, Issue 2-3 Pages 211-221
Susan H. Sutheimer and Stephen E. Cabaniss*

Abstract: Samples (20-100 µL) were injected into a carrier stream (1 ml/min) of 100 mM acetate buffer of pH 5.2 reacted at 55-57°C in a mixing coil with 1.8 mM lumogallion (100 µL/min). After passing through a second mixing coil at room temperature, fluorimetric detection at 595 nm (excitation at 500 nm) was achieved. Calibration graphs were linear over the range 36 nM- to 3.6 µM-Al with a detection limit of 3.7 nM-Al. At 1.1 µM-Al an RSD (n = 6) of 0.8% was obtained. The kinetics of formation the Al-lumogallion chelate is discussed. Comparative results were obtained with the treatment of 10 mL of sample with Al(III) in 2% HNO3 and using 10 µL of 1 g/l magnesium nitrate in 2% as a matrix modifier and GFAAS.
Aluminum Environmental Fluorescence

"Routine Assay Of Creatinine In Newborn Baby Urine By Spectrophotometric Flow Injection Analysis"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 446-450
Tadao Sakai*, Hiroshi Ohta, Noriko Ohno and Junzo Imai

Abstract: An FIA method based on the Jaffe reaction was described for the determination of creatinine in urine. Urine was collected on a soft adsorbent cotton pad. The soaked pad was wrung to recover 0.5 mL urine. The urine sample was diluted with 4.5 mL 0.03 M KH2PO4 containing 0.4% EDTA (carrier solution). A 100 µL portion of this solution was injected into the carrier stream (0.82 ml/min) which was merged with the reagent stream (0.82 ml/min) containing 0.01 M sodium picrate in 1.5% NaOH. The flow passed through the reaction coil (1.5 m x 0.5 mm i.d.) at 50°C to the detector where the absorbance was measured at 515 nm using a 10 mm pathlength flow cell. The calibration graph was linear for 5-200 µg/ml of creatinine with a detection limit of 3 µg/ml. The RSD (n = 10) for the determination of 50 µg/ml creatinine was 0.6%. The results were consistent with those obtained by a batchwise experiment and LC.
Creatinine Urine Spectrophotometry

"Construction And Use Of A Tubular Picrate Ion-selective Electrode For Reducing Sugar Determination In Port Wine By Flow Injection Analysis"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 122-128
Teresa I. M. S. Lopesa, Ant&oacute;nio O. S. S. Rangela,*, Jos&eacute;L. F. C. Limab and M. Concei&ccedil;&atilde;o B. S. M. Montenegrob

Abstract: An FIA system equipped with a picrate ISE was described for the determination of reducing sugars in port wine. The determination was based on the reaction between the reducing sugars and picric acid and the measurement of the decrease in the picrate concentration by a tubular, flow-through detector. A 150 µL volume of wine was injected into a 0.045 M picric acid carrier stream (0.7 ml/min) which was merged with a 1.8 M NaOH stream (0.2 ml/min). After passing through a thermostatted water bath at 58°C, the flow was merged with a 1 M H2SO4 stream (0.2 ml/min). The flow passed through a 100 cm mixing coil to the detector. The calibration graph was linear for 25-200 g/l of reducing sugars and the RSD were 3.9%. The sampling frequency was ~e;50 samples/h. The results obtained for samples containing 98-148 g/l of reducing sugars were in agreement with those obtained by an iodometric reference method.
Sugars, reducing Port Wine Electrode Electrode

"Spectrofluorimetric Flow Injection Determination Of Potassium In Serum Based On Enzyme Activation"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 178-186
J. M. Fern&aacute;ndez-Romeroa, M. D. Luque De Castroa,* and R. Quiles-Zafrab

Abstract: The activation of the pyruvate kinase (PK) catalyzed reaction between phospho(enol)pyruvate (PEP) and ADP by K formed the basis of the FIA method. The product, pyruvate, was treated with NADH in the presence of lactate dehydrogenase (LDH) and the decrease in concentration of NADH was monitored at 460 nm. The decrease in NADH concentration was proportional to K+ concentration. Na+ interference was eliminated by a constant concentration of Li+ in the samples. The interference due to ammonium was eliminated by its conversion to glutamate via glutamate dehydrogenase (GDH). Three enzyme reactors containing immobilized GDH, PK and LDH were connected in series to form the FIA manifold. A carrier solution containing 200 mM triethanolamine, 10 mM Mg2SO4 and 40 mM LiCl of pH 7.2 was used at 0.3 ml/min. Serum was diluted 100-fold with 3 mM Kriptofix-221 in carrier buffer and injected into the carrier stream. The carrier stream was merged with a reagent stream (0.3 ml/min) containing 6 mM ADP/6 mM PEP/0.5 mM NADH in carrier buffer and passed through the enzyme reactors at 37°C to the spectrophotometric detector. The calibration graph was linear for 1-10 µM-K. Recoveries of 1-3 mM K were 95-105%. RSD (n = 8 or 11) for 2-8 mM K.
Potassium Blood Serum Fluorescence

"Fluorimetric Flow Injection Determination Of Theophylline Based On Its Inhibitory Effect On Immobilized Alkaline Phosphatase"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 159-163
M. S&aacute;nchez-Cabezudo, J. M. Fern&aacute;ndez-Romero and M. D. Luque de Castro*

Abstract: The dual channel flow injection manifold for the determination of theophylline consisted of a dual injection valve, a reactor at 40°C containing bovine alkaline phosphatase immobilized on controlled pore glass and a fluorimetric detector. Sample (500 µL) and 225 µL 2 mM 4-methylumbelliferone phosphate solution (substrate) were simultaneously injected into two carrier streams (both at 1.2 ml/min) of 0.5 M Tris hydrochloride buffer of pH 10. The streams were merged and the flow was passed through the reactor (50 cm x 0.5 mm i.d.) to the detector. The released 4-methylumbelliferone was detected at 445 nm (excitation at 365 nm). The presence of theophylline inhibited the enzymatic reaction and reduced the fluorimetric signal. The calibration graph was linear for 10^-200 µM-theophylline and the RSD (n = 3) at the 20 µM level was 3.5%. The sampling frequency was 40 samples/h. The recovery of 20-60 µM-theophylline from spiked blood serum was >93%.
Theophylline Blood Serum Fluorescence

"Flow Injection Stopped-flow Spectrofluorimetric Kinetic Determination Of Total Ascorbic Acid Based On An Enzyme-linked Coupled Reaction"
Anal. Chim. Acta 1995 Volume 309, Issue 1-3 Pages 271-275
Houping Huang,*, Ruxiu Cai, Yumin Du and Yune Zeng

Abstract: Wine, beer or urine were adjusted to pH 6 with HCl or NaOH and 0.1 M EDTA added. Solid dose formulations of ascorbic acid were dissolved in 100 mL 1% oxalic acid and liquid formulations of ascorbic acid were diluted with water. To 1 mL portions containing ~0.5 µg/ml of ascorbic acid were added 5 µL aqueous 2 mg/ml of laccase and the solution injected in parallel with 10 mL 20 µM-o-phenylenediamine in 250 µM-phosphate buffer of pH 6 into a carrier stream (2 ml/min) of water and mixed in a 5 cm reaction coil at 35°C, and fluorimetric detection at 430 nm (excitation at 360 nm). Calibration graphs were linear for 0.025-1 µg/ml of ascorbic acid. Quantitative recoveries of ascorbic acid in the presence of Fe(III), Cu(II) and a range of common biochemical substrates were obtained, excepting L-cystine, L-cysteine, tyrosine and NH3OHCl.
Ascorbic acid, total Beer Wine Urine Pharmaceutical Fluorescence

"Multicommutation In Flow Analysis. 3. Spectrophotometric Kinetic Determination Of Creatinine In Urine Exploiting A Novel Zone Sampling Approach"
Anal. Chim. Acta 1995 Volume 310, Issue 3 Pages 447-452
Alberto N. Ara&uacute;joa, Jos&eacute;L. F. Costa Limaa, Boaventura F. Reisb,* and Elias A. G. Zagattob

Abstract: A single channel flow manifold equipped with three microcomputer-controlled three-way solenoid valves is described for the spectrophotometric determination of creatinine in urine using Jaffe's reaction. A plug of untreated urine was inserted into a reagent stream (0.9 ml/min) of 0.012 M picric acid in 0.48 M NaOH and passed through a heated reactor coil at 37°C (100 cm x 0.8 mm i.d.) to the spectrophotometer for detection. The volume of urine sampled and the residence time in the reaction coil were determined by controlling the switching of the solenoid valves. Volumes as low as 0.5 µL of urine were sampled. The optimized system was employed for the analysis of standard solutions containing 0.5-2 g/l creatinine and six urine samples. The RSD (n = 10) for the determination of 1.26 g/l creatinine was 2.9%. The sampling frequency was ~e;24 samples/h. Calibration graphs are shown.
Creatinine Urine Spectrophotometry

"Determination Of Branched-chain L-amino-acids By Flow Injection Analysis With Co-immobilized Leucine Dehydrogenase/NADH Oxidase And Chemiluminescence Detection"
Anal. Chim. Acta 1995 Volume 311, Issue 1 Pages 71-76
Nobutoshi Kiba*, Akira Kato and Motohisa Furusawa

Abstract: An enzyme reactor column (5 cm x 4 mm i.d.) containing leucine dehydrogenase and NADH oxidase co-immobilized on to aminated poly(vinyl alcohol) beads was incorporated into a FIA system for the determination of branched-chain L-amino-acids (BCAA). Sample (20 µL) was injected into a 2 mM NAD+ carrier solution (0.15 ml/min) and merged with a stream of 2 mM luminol in 0.4 M carbonate buffer at pH 10 (0.15 ml/min). The flow passed through the enzyme reactor column at 40°C. The eluate from the reactor column was merged with a 10 mM potassium hexacyanoferrate stream (0.3 ml/min) before passing through a mixing coil (50 cm x 0.5 mm i.d.) to the detector flow cell (100 µL) where the chemiluminescence was measured. The calibration graph was linear for 0.5-600 µM-BCAA (based on L-isoleucine) and the detection limit was 0.3 µM. RSD (n = 7) was 0.78% at the 15 µM level. The method was applied to the determination of BCAA in human plasma. Plasma samples were diluted 10-fold with 0.1 M carbonate buffer at pH 10 prior to analysis. The within day and day-to-day coefficients of variation for the determination of 436 µM-BCAA in plasma were 0.87 and 1.6%, respectively. The recoveries of 546 µM-2.45 mM BCAA from plasma were 98-102%.
Amino acids, L Plasma Human Chemiluminescence

"Evaluation Of Flow Injection Methods For Ammonium Determination In Waste Water Samples"
Anal. Chim. Acta 1995 Volume 311, Issue 2 Pages 165-173
A. Cerd&agrave;, M. T. Oms, R. Forteza and V. Cerd&agrave;*

Abstract: Five flow injection methods, namely (i) the Berthelot reaction adapted to FIA, (ii) the Berthelot reaction in combination with gas diffusion separation, (iii) the salicylate modification of the Berthelot reaction, (iv) an acid-base spectrophotometric method with gas diffusion separation and (v) gas diffusion separation with conductivity detection, were compared for the determination of ammonia in waste water. The linear range, detection limit and reproducibility of each method were measured. All methods produced a detection limit (0.03-1 mg/l) which was satisfactory for the determination of ammonia in waste water. Interferences were eliminated by using gas diffusion separation. Gas diffusion methods coupled with spectrophotometric or conductometric detection were found to have good precision and sensitivity and were reliable alternatives to the Berthelot methods. The conductivity method had the added advantage of requiring only one reagent (NaOH). Methods based on the Berthelot reaction required a reaction temperature of 60°C which made them unsuitable for in situ applications. All five method were applied to the analysis of waste water samples containing 5-60 mg/l ammonia and the results were compared.
Ammonium Waste Conductometry Spectrophotometry

"Effect Of Solvent Properties On The Dispersion Coefficient In An Online Microwave Flow Injection System"
Anal. Chim. Acta 1995 Volume 314, Issue 3 Pages 213-218
Xingguo Chen, Yanjun Xu and Zhide Hu*

Abstract: The dispersion behavior of solutes in an online microwave flow injection system was studied using four chromogenic reagents as model solutes and the solvents methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol and pentan-1-ol as carrier streams. The flow injection manifold consisted of a reaction coil (10 m x 0.5 mm i.d.) mounted inside a microwave oven and coupled to a UV-visible spectrophotometric detector. The measurements were carried out by injecting 520 µL 34-80 µM-chromogenic reagent into the carrier stream (1.78 ml/min). When the solute plug reached the microwave oven, the oven was switched on for 0-30 s at 533 W. The solute plug passed through the reaction coil to the detector cell (5 mm optical path, 11.3 µL volume) where the absorbance was monitored at the maximum absorption wavelengths. The dispersion coefficient for each chromogenic reagent was calculated from the absorbance values. The relationship between the dispersion coefficients and the physical properties and structural parameters of the solvents were investigated. When the microwave heating time was fixed there was a linear relationship between the dispersion coefficients and the molar volume, b.p., molecular connectivity index, expanded solubility parameter and viscosity of the solvent.
Spectrophotometry

"Micelle Enhanced Spectrofluorimetric Assay For Laccase Activity By A Flow Injection Stopped-flow Technique"
Anal. Chim. Acta 1995 Volume 318, Issue 1 Pages 63-69
Houping Huang*, Ruxiu Cai, Yumin Du, Zhixin Lin and Yune Zeng

Abstract: An automated flow injection stopped-flow kinetic spectrofluorimetric method for determination of laccase activity is proposed. It is based on the oxidation of o-phenylenediamine (1,2-diaminobenzene) catalyzed by laccase during the stopped-flow period, yielding 2,3-diaminophenazine, which is determined by a micelle enhanced spectrofluorimetric method in a non-ionic surfactant medium. The substrate solution with Brij-35 and the buffer with sample are pumped into the flow manifold at the same flow rate and merged in the flow cell, then stopped for measuring the fluorescence intensity (lambda-ex = 425 nm, lambda-em = 530 nm) which increases with time, at a constant temperature of 46°C. The linear range of the method is 0.1-118 U L-1 with a detection limit of 0.07 U l-1, using a 5 min stopped-flow reaction time. The proposed method has been applied to the assay for laccase activity of real samples at 10 samples per h.
Enzyme, laccase Fluorescence

"Determination Of Formaldehyde In Frozen Fish With Formaldehyde Dehydrogenase Using A Flow Injection System With An Incorporated Gel-filtration Chromatography Column"
Anal. Chim. Acta 1996 Volume 320, Issue 2-3 Pages 155-164
Iben Ellegaard Bechmann

Abstract: Frozen fish was thawed and 10 g portions were homogenized in 10 mL 10 mM Tris buffer of pH 7.8. Homogenates were centrifuged and the supernatant was filtered. Portions of the filtrate were injected in to a Tris buffer carrier of pH 7.8 (0.75 ml/min) and passed through a Sephadex G-25 (20-80 µm) gel filtration column to remove proteins, before injection into a stream of 50 mM phosphate buffer of pH 7.8 (0.75 ml/min). This merged with a similar stream (0.35 ml/min) into which formaldehyde dehydrogenase/NAD had been injected. After reaction at 40°C in a coil (75 cm x 0.5 mm i.d.) photodiode array detection at 340 nm was performed. The method was faster than standard methods and less affected by interferences. The limit of detection was 2.5 mg/l formaldehyde. A calibration graph for up to 50 mg/l is shown. Sample throughput was 10 per hour. The results were compared with those obtained by the Nash test.
Formaldehyde Marine Spectrophotometry

"A Combined Sampling And Delay Unit For Flow Injection Analysis. The Automated Determination Of 2-thiobarbituric Acid-reactive Substances In Foods"
Anal. Chim. Acta 1996 Volume 322, Issue 1-2 Pages 69-76
S&oslash;ren Storgaard J&oslash;rgensen* and Gitte S&oslash;rensen

Abstract: A sampling and delay unit for FIA is described that permits individual samples to be retained for a specified time before being propelled to the detector. The unit consists of two discs (13 cm diameter) fitted together in the horizontal plane. Eight pairs of holes are drilled in the lower disc and a reaction coil is fitted to each pair. Two pairs of holes are drilled in the upper disc in positions that coincide with the holes in the lower disc. By rotating the lower disc with respect to the upper disc, sequential access is obtained to each reaction coil for removing the reaction mixture and recharging. The reaction coils are immersed in a water bath for temperature-controlled reactions. The unit was used for the automated determination of 2-thiobarbituric acid-reactive substances in foods, a measure of lipid oxidation. The method was based on the spectrophotometric detection at 532 nm of the red chromophore formed by reaction of 2-thiobarbituric acid with the product of lipid oxidation. The calibration graph obtained by the proposed automated method showed good correlation with that obtained by a manual method. Meat samples were analyzed by both methods and the results are compared.
2-thiobarbituric acid Food Meat Spectrophotometry

"Automated Determination Of Lactulose In Milk Using An Enzyme Reactor And Flow Analysis With Integrated Dialysis"
Anal. Chim. Acta 1996 Volume 324, Issue 1 Pages 37-45
Michael Mayer, Meike Genrich, Wolfgang K&uuml;nnecke and Ursula Bilitewski*

Abstract: The automated FIA method was based on the enzymatic hydrolysis of lactulose to fructose and galactose followed by the separation of fructose by dialysis and its detection by fructose dehydrogenase (FDH) catalyzed oxidation with ferricyanide as electron acceptor. The manifold allowed a sample stream (0.1 ml/min) to be merged with the reaction buffer stream (0.1 ml/min) containing 185 iu/ml β-galactosidase in phosphate buffer of pH 5. The flow was propelled through a reaction coil (1.3 m x 0.8 mm i.d.) operated at 50°C and the donor channel of the dialysis cell. The acceptor channel (64 mm x 2 mm x 0.5 mm) of the dialysis cell contained stationary 2 mM potassium ferricyanide in phosphate/citrate buffer of pH 5.5. After a dialysis period of 180 s, the acceptor solution was pumped through the FDH enzyme reactor to an amperometric detector where the ferrocyanate was re-oxidized. The amperometric detector was equipped with a screen-printed Pt electrode at +385 mV vs. Pt reference. The method was applied to the analysis of milk samples using a standard-addition calibration procedure. Lactulose concentrations of up to 12.28 mM were measured and these results were confirmed by a photometric method. The sampling frequency for the proposed method was 17 samples/h.
Lactulose Milk Amperometry Electrode

"Pervaporation: An Interface Between Fermentors And Monitoring"
Anal. Chim. Acta 1996 Volume 330, Issue 2-3 Pages 265-272
I. Papaefstathioua, U. Bilitewskib and M. D. Luque de Castroa,*

Abstract: An enzymatic spectrophotometric method is described for determining acetaldehyde in fermentation broths. A 1 mL sample of the fermentation broth is injected into a carrier stream of water and propelled at 0.49 ml/ml through a pervaporation module (at 60°C) fitted with a PTFE membrane (1.5 mm thickness, 5 µm pore size). The vaporized acetaldehyde diffuses through the membrane and is collected in an acceptor stream (0.49 ml/min) containing 1 mM NAD+, 0.2 M KCl and 6 mM 2-mercaptoethanol in 0.1 M Na2HPO4/NaH2PO4 buffer at pH 8. The acceptor stream passes through an enzyme reactor (at 30°C) containing aldehyde dehydrogenase immobilized on controlled-pore glass beads and a spectrophotometric detector equipped with a 1 cm detector cell; the NADH formed by the enzymatic oxidation of acetaldehyde is detected at 340 nm. The calibration graph was linear for 1-30 µg/ml of acetaldehyde, the detection liwas 0.9 µg/ml and the RSD (n = 8) at 20 µg/ml was 2.7%. The sampling frequency was 8 per h. The recoveries of 6.5 µg/ml of acetaldehyde added to fermentation broths containing 2-15 µg/ml of acetaldehyde were >92.7%.
Acetaldehyde Fermentation broth Spectrophotometry

"Online Monitoring Of Trace Amounts Of Copper(II) In Steam Condensate And Boiler Feed-water By Flow Injection Analysis Based On Its Catalytic Effect On The Oxidation Of Hydroquinone By Hydrogen Peroxide"
Anal. Chim. Acta 1996 Volume 331, Issue 3 Pages 257-262
Shun-an Cao, Jin-chang Zhong, Kiyoshi Hasebe and Wenzhi Hu*

Abstract: The FIA method for determining trace amounts of Cu(II) was based on the catalytic effect of Cu(II) on the oxidation of hydroquinone by H2O2. A 150 µL sample was injected into a carrier stream formed online by merging 3% H2O2 with phosphate buffer of pH 7.2 (both at 2 ml/min). The resulting mixture was merged with 0.3 M hydroquinone (2 ml/min) and passed through a reactor coil (600 cm x 1 mm i.d.) at 55°C to the spectrophotometric detector where the absorbance at 490 nm was monitored. Calibration was carried out using solutions containing 5-100 µg/l Cu(II). The detection limit was 0.25 µg/l. The RSD (n = 11) for 5-50 µg/l Cu(II) were 0.81-0.86%. The method was applied to monitor Cu(II) in steam condensates and boiler feed water. The recoveries of 5-10 µg/l Cu(II) from spiked boiler feed water and steam condensate were 97-104.4% and 90-116%, respectively.
Copper(II) Water Water Spectrophotometry

"Direct Vapor Generation Fourier Transform Infrared Spectrometric Determination Of Ethanol In Blood"
Anal. Chim. Acta 1996 Volume 336, Issue 1-3 Pages 123-129
Amparo P&eacute;rez-Ponce, Salvador Garrigues and Miguel de la Guardia*

Abstract: A new procedure is proposed for a direct determination of ethanol in plasma and whole blood. The method is based on the injection of a discrete sample volume of 10 l into an electrically heated Pyrex glass reactor in which, at a temperature of 90°C, the ethanol is volatilized and introduced by means of a N2 carrier flow inside a long-path infrared gas cell and the corresponding flow analysis recording registered as a function of time. The measurement of the area of the flow injection recording, obtained from the absorbance of the transient signal in the range 1150-950 cm-1, allows the direct quantification of ethanol upto 2 g l-1, with a limit of detection of 0.020 g L-1 and coefficient of variation between 0.3 and 1.9% for three replicate analyzes of the same sample. The analysis frequency of the method is 40 h-1, and it can be applied to a single drop of finger blood.
Ethanol Whole Spectrophotometry

"Study Of Equilibria In Cyanide Systems By Gas Diffusion Measurement Of Hydrogen Cyanide"
Anal. Chim. Acta 1996 Volume 336, Issue 1-3 Pages 131-140
Jamal A. Sweileh

Abstract: Speciation of hydrogen cyanide in different metal-cyanide systems at the µg mL-1 level was established by the selective measurement of hydrogen cyanide (HCN) diffused through a microporous Teflon membrane under thermodynamic equilibrium conditions. The test solution was continuously aspirated through the donor side of the gas diffusion unit until equilibrium was achieved with the stagnant buffer solution on the receptor side. The final assay of HCN was carried out spectrophotometrically (chloramine-T/barbiturate/isonicotinate) in the flow injection mode. The theoretical relation between the enrichment factor and the pH of the donor and receptor solutions was derived and experimentally verified. As confirmed by calculation the speciation of HCN can be established for simple soluble cyanides and cyanide complexes with log formation constants as high as 20. For more stable cyanide complexes the results are satisfactory; but for the highly stable hexacyanoferrate(III) this method is not feasible. The speciation of cyanide in metal-cyanide systems was studied by measuring the HCN concentration using a gas diffusion cell incorporated into a flow injection spectrophotometric system. The metal-cyanide test solution was pumped (2 ml/min) through the donor channel of the gas diffusion cell for 6 min until equilibrium was reached. During this period the acceptor solution, 0.1 M NaH2PO4 of pH 7, was kept stationary. At the end of the sampling period, the acceptor solution was injected into a carrier stream (0.4 ml/min) of 0.1 M NaH2PO4 of pH 7 and merged with 0.01% chloramine-T (0.4 ml/min) and sodium barbiturate/sodium isonicotinate reagent (1.6 ml/min). The mixture was heated to 68°C and propelled to the detection cell where the absorbance was monitored at 600 nm. The acceptor and donor channels of the gas diffusion cell had volumes of 0.108 mL. The apparatus was calibrated with 0.1-1 µg/ml NaCN. The calibration graph was linear, the detection liwas 0.025 ng/ml and the RSD (n = 9) for 0.5 µg/ml cyanide was 0.6%. The method was applied to metal-cyanide complexes at various pH values from 2-11. At each pH the concentration of each species was calculated using two mass balance equations, one for total cyanide and the other for total metal. 19 References
Hydrogen cyanide Spectrophotometry

"Determination Of Sucrose Using Sucrose Phosphorylase In A Flow Injection System"
Anal. Chim. Acta 1997 Volume 337, Issue 1 Pages 107-111
Mamie Kogure, Hisakazu Mori*, Hisano Ariki, Chika Kojima and Haruhiko Yamamoto

Abstract: The fluorimetric determination of sucrose was accomplished using a single-channel flow manifold incorporating an enzyme reactor (8 cm x 2 mm i.d.) prepared by immobilizing 5 iu sucrose phosphorylase/11 iu phosphoglucomutase/4 iu glucose 6-phosphate dehydrogenase on to 0.4 g aminopropyl glass beads (200-400 mesh, 500 angstrom pore size). The determination was carried out by injecting a sample (50 µL) into a carrier stream at a flow rate of 0.4 ml/min containing 30 mM KH2PO4/3 mM MgCl2/1 mM NADP+/0.05 mM glucose 1,6-diphosphate in 200 mM PIPES buffer of pH 7.5. The stream was propelled through the enzyme reactor at 30°C and into the detection cell (12 µL volume); detection was at 460 nm (excitation at 340 nm). The calibration graph was linear from 0.1-200 µM sucrose; the detection limit was 0.1 µM. The method was applied to the determination of sucrose in soft drinks. The samples were diluted 1000-fold prior to analysis and the phosphate concentration in the carrier stream was increased to 100 mM to reduce the inhibiting effects of fructose. The detection limit was 0.2 µM sucrose. RSD was 1.06% (n = 5) for 50 µM-sucrose.
Sucrose Soft drink Fluorescence

"Determination Of Chlorine Dioxide Using 4-aminoantipyrine And Phenol By Flow Injection Analysis"
Anal. Chim. Acta 1997 Volume 341, Issue 2-3 Pages 257-262
Takaho Watanabe*, Toshikazu Ishii, Yoshihiro Yoshimura and Hiroyuki Nakazawa

Abstract: A flow injection spectrophotometric method was developed for determining ClO2 in the presence of metal ions and various chlorinated species that can occur under normal water treatment conditions. ClO2 was separated from the water sample using a purge-trap system with a 15 min purge time, N2 purge gas at 600 ml/min and a sample temperature of 25°C. The trapping solution was analyzed by injecting a measured volume into a Tris hydrochloride buffer carrier stream (0.5 ml/min) which was merged with a reagent stream (2 ml/min) containing 0.8 mM 4-aminoantipyrine and 2 mM phenol in Tris hydrochloride buffer of pH 9. The mixture was passed through a heated coil (0.3 m x 0.5 mm i.d.) at 30°C and the absorbance was measured at 503 nm. The calibration graph was linear for 0.005-1.5 ppm ClO2, the detection limit was 5 ppb and the RSD for 0.05 ppm ClO2 was 2.4%.
Chlorine dioxide Environmental Spectrophotometry

"Determination Of Arsenic(III) And Arsenic(V) By Flow Injection Hydride-generation Atomic Absorption Spectrometry Via Online Reduction Of Arsenic(V) By Potassium Iodide"
Anal. Chim. Acta 1997 Volume 343, Issue 1-2 Pages 5-17
Steffen Nielsen and Elo H. Hansen

Abstract: The flow injection method for the determination of total As was based on the online reduction of As(V) to As(III) by ascorbic acid/KI reagent. Sample (100 µL) in a 4 M HCl carrier stream (9.5 ml/min) containing 0.5% ascorbic acid and 1% KI was propelled through a reaction coil (150 cm x 0.5 mm i.d.) at 140°C and a cooling coil (75 cm x 0.5 mm i.d.) at 10°C and then merged with 0.05 M NaBH4 (1.6 ml/min). The mixture was passed to a gas-liquid separator and arsine and H2 were swept to the atomizer cell (at 900°C) by an Ar carrier stream. The absorption signal for As was recorded at 193.7 nm. The same flow manifold was used for the selective detection of As(III) by using a carrier stream of 0.03 M HCl which did not contain the reducing reagents. The detection limits were 37 ng/l for total As and 111 ng/l for As(III). The RSD (n = 10) for 5 µg/l total As and As(III) were Calibration graphs were linear for 0.1-10 µg/l total As. The method was validated by analyzing certified drinking water using the multiple standard additions calibration procedure. A volume-based flow injection (FI) procedure is described for the determination and speciation of trace inorganic arsenic, As(III) and As(V), via hydride generation-atomic absorption spectrometry (HG-AAS) of As(III). The determination of total arsenic is obtained by online reduction of As(V) to As(III) by means of 0.50% (w/v) ascorbic acid and 1.0% (w/v) potassium iodide in 4 M HCl. The combined sample and reduction solution is initially heated by flowing through a knotted reactor immersed in a heated, thermostatted oil bath at 140°C, and subsequently, for cooling the reaction medium, a knotted reactor immersed in a water bath at 10°C. By using the very same volume-based FI-HG-AAS system without the heating and cooling reactors, and employing mild hydrochloric acid conditions, As(V) is not converted to arsine, thereby allowing the selective determination of As(III). The injected sample volume is 100 µl while the total sample consumption per assay is 1.33 ml, and the sampling frequency is 180 samples per hour. The detection limit (3s) for the online reduction procedure was 37 ng L-1 and at the 5.0 µg L-1, the relative standard deviation (RSD) was 1.1% (n=10) by calibrating with As(III) standards; by calibrating with As(V) standards the detection limit was 33 ng L-1 and the RSD was 1.3% (n=10). For the selective determination of As(III) the detection limit was 111 ng L-1 and the RSD was 0.7% (n=10) at 5.0 µg L-1. Both procedures are most tolerant to potential interferents. Thus, without impairing the assay, interferents such as Cu, Co, Ni and Se could, at a As(V) level of 5 µg L-1, be tolerated at a weight excess of 2000, 30000, 200 and 200 times, respectively. The assay of a certified drinking water sample by means of multiple standard addition (five levels; each three replicates) was 9.09±0.05 µg L-1 (certified value 9.38±0.71 µg l-1). 11 References
Arsenic(3+) Arsenic(5+) Water DWQI VKI-3-30494 Spectrophotometry

"Modeling And Optimization Studies For A Sequential Flow Based Bio-analytical System"
Anal. Chim. Acta 1998 Volume 359, Issue 1-2 Pages 157-171
Sameer Parab, Bernard J. Van Wie*, Ian Byrnes, Edgar J. Robles, Bruce Weyrauch and Thomas O. Tiffany

Abstract: The clinical applications of the sequential flow technique are emphasized in this study by considering glucose determinations in a standard blood chemical analysis. The sequential flow configuration is modeled to predict experimental behavior. A rigorous theoretical formulation of the model is presented incorporating temperature relationships for the hydrodynamic and kinetic parameters. A comparisons of model predictions with experiments show agreement satisfactory for determining optimal design strategies. To perform this analysis, factorial design results of model predictions are used to locate regions where a full set of model predictions should be made. Also, experimental results and theoretical predictions are used to determine the best temperature for glucose determinations
Glucose Blood

"Simultaneous Calibration In Flow Injection Analysis Using Multiple-injection Signals Evaluated By Partial Least Squares"
Anal. Chim. Acta 1998 Volume 363, Issue 2-3 Pages 183-189
Karsten Sch&ouml;ngarth and Bernd Hitzmann*

Abstract: In this contribution, a new calibration technique for flow injection analysis is presented. The technique is based on a multiple-injection system complemented with multivariate evaluation. A standard the sample and another standard solution are injected in a fast sequence. A partial mixing of the solutions occurs due to dispersion. However, the overlapping measurement signals can be deconvoluted reliably employing partial least-squares regression. The simultaneous calibration technique enables a fast adaptation to changes in the reaction system, while the time lost by rapid threefold injection and the signal evaluation is minimal. Applying simultaneous calibration the change of the sensor sensitivity is considered inherently. To test the simultaneous calibration technique, it was applied to measurements of a flow injection system for the determination of glucose while the temperature of the reaction coil was changed.
Glucose

"A Thermistor As A Sensor In Gas Phase Flow Injection Analysis"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 5-10
Shan-Jun Liu and Matthieu Tubino*

Abstract: A flow injection thermometric procedure based on a flow-through thermometric detector for measuring the heat effects of a phys. mixing or a chemical reaction is described. For comparison the following heat delivering systems were studied: mixing of water/water; air/water or air/air; neutralization reaction of sulfuric acid with sodium hydroxide; and gas phase reaction of carbon dioxide with ammonia in the presence of water vapor. Emphasis was given to the evaluation of the influence of the introduction of a small sample volume into the flow systems and the effect of flow rate on the signal and the sampling frequency.
Thermistor

"Direct Spectrophotometric Determination Of Chromium By Microwave-oven Induced Flow Injection Analysis"
Anal. Chim. Acta 1998 Volume 374, Issue 1 Pages 61-66
Xiaoyuan Wu, Hui Zhao, Xingguo Chen, Zhide Hu*, Zhengfeng Zhao and Martin Hooper

Abstract: Two sensitive flow injection methods were developed for the determination of traces of Cr(VI), based on the very efficient microwave-accelerated reactions of Cr2O72- with dibromocarboxyarsenazo (DBM-AsA, in System 1) and dibromo-o-carborylchlorophonazo (DBOK-CPA, in System 2). The reactions are followed spectrophotometrically by measuring the decrease in the absorbance of DBM-AsA at 535 nm or DBOK-CPA at 556 nm. The sampling frequency for both systems is 40 h-1. The calibration graphs are linear at 1.62-27.0 µg mL-1, and 0.40 and 10.80 µg mL-1 for Systems 1 and 2, respectively. The respectively. detection limits are 0.087 and 0.10 µg mL-1. The methods were applied to determine traces of Cr in a steel sample and electroplating solutions with satisfactory results.
Chromium(VI) Alloy Industrial Spectrophotometry

"Spectrophotometric Determination Of Silicon In Silicate By Flow Injection Analysis"
Talanta 1985 Volume 32, Issue 5 Pages 353-357
Rokuro Kuroda, Iwao Ida and Hideki Kimura

Abstract: Silicon in silicate rocks was determined at 70 samples h-1, with coefficient of variation of 0.5%. The rock was fused with Li2CO3 - H3BO3 (1:1) at 1000°C for 15 min, cooled and dissolved in HCl. Silicic acid was isolated on a column (3 cm x 8 mm) of Bio-Rad AG 50W-X8 (H+-form) and then depolymerized in alkaline medium before determination by either a static or flow injection spectrophotometric method as silicomolybdic acid (λmax = 440 nm). The flow injection analysis system consisted of two channels containing the carrier solution (0.1 M NaOH) and the 1% ammonium molybdate reagent in 0.2 M H2SO4, and which allowed the color reaction to proceed in a coil (3 m x 1 mm) at 50°C. The proposed method was applied to 14 standard rock samples to give results in good agreement with the certified values and with the values obtained by conventional spectrophotometry. Up to ~2% of P2O5 did not interfere.
Silicon Silicate Geological Silicate Spectrophotometry

"Fluorimetric Determination Of Nitrite In Natural Waters With 3-aminonaphthalene-1, 5-disulfonic Acid By Flow Injection Analysis"
Talanta 1986 Volume 33, Issue 9 Pages 729-732
Shoji Motomizu, Hiroshi Mikasa and Kyoji T&ocirc;ei

Abstract: Nitrite was determined in a flow injection system with water as carrier, and 10 µM-3-aminonaphthalene-1,5-disulfonic acid - 1 mM Na2EDTA - 2 M HCl as reagent stream. Following reaction in a PTFE tube (13 m x 0.5 mm) at 90°C, the stream was mixed with aqueous 20% NaOH solution, and the resulting azoic acid salt was detected spectrofluorimetrically at 470 nm (excitation at 365 nm). Calibration graphs rectilinear over various ranges from 0.1 to 50 µM were obtained by varying the sensitivity of the detector. The detection limit was 1 nM and the coefficient of variation at 1 µM was 0.4% (n = 10). Sodium chloride (>0.2M) interfered, but many ions did not. Results for various natural waters agreed well with those of other methods.
Nitrite River Sea Fluorescence

"Determination Of Ultratrace Amounts Of Cobalt By Catalysis Of The Tiron-hydrogen Peroxide Reaction With An Improved Continuous-flow Analysis System"
Talanta 1987 Volume 34, Issue 2 Pages 277-281
Kenji Isshiki, Eiichiro Nakayama

Abstract: A schematic diagram is given of the continuous-flow system in which air segmentation is introduced after mixing of the reactants, which were samples in 0.1 M HCl, 0.05 M Na2CO3 - NaHCO3 in 0.1 M NaOH, 0.01 M tiron and 5 mM H2O2. Optimum conditions were a reaction time of 210 s, a temperature of 30°C, pH 11.2, and absorbance measurement at 440 nm. From 3 to 5000 pg of Co(II) can be determined in 1 mL of acidified sample, at a rate of 40 samples h-1. The coefficient of variation (n = 10) were 1 and 3% for 100 and 10 pg mL-1 of Co, respectively. A considerable number of species interfere when present in 100-fold amounts relative to Co and must be removed before determination. Results are given for the determination of Co in seawater.
Cobalt Sea Spectrophotometry

"Determination Of Ortho- And Pyrophosphates In Waters By Extraction Chromatography And Flow Injection Analysis"
Talanta 1990 Volume 37, Issue 10 Pages 889-894
B. Ya. Spivakov, T. A. Maryutina, L. K. Shpigun, V. M. Shkinev and Yu. A. Zolotov, E. Ruseva and I. Havezov

Abstract: A flow injection manifold is described which includes an extraction mini-column and a post-column spectrophotometric detector. The sum of ortho- and pyro-phosphate was determined in an aqueous sample by hydrolysis of the pyrophosphate at 50°C using inorganic pyrophosphatase, then the solution was mixed with a stream of 1 M HNO3 before passage through a column of Chromaton N-AW-HMDS modified with dioctyltin dichloride. The column was washed with water and Tris - HCl buffer for 1 min, and total orthophosphate was eluted with 0.5 M HCl. The orthophosphate was determined by mixing the solution with 1 M HNO3, pumping the stream through the column and elution with HCl as before, followed by monitoring the absorbance at 660 nm of the molybdenum blue produced in a reaction coil. For a sample volume of 6 ml, the calibration graph was rectilinear from 5 to 100 ng mL-1 of P, and the detection limit was 0.3 ng mL-1. The recovery of the ions was >96%. The method was used for the analysis of river water.
Phosphate Pyrophosphate River Spectrophotometry Sample preparation

"Determination Of Trace Amounts Of A Proteolytic Enzyme By FIA With A Stopped-flow And An Online Preconcentration Technique"
Talanta 1991 Volume 38, Issue 8 Pages 851-856
Thomas G&uuml;beli, Jaromir Rika* and Gary D. Christian,

Abstract: In the cited technique (diagram and details given) 5 mM N-succinyl-L-Ala-L-Ala-L-Pro-(4'-nitrophenylalaninamide) substrate was injected into a stream of-Tris-HCl buffer (pH 8.3) and this stream was merged with the enzyme sample solution The mixture was incubated at 40°C for 5 to 30 min during the stopped-flow period and the hydrolysis product, p-nitroaniline was concentrated on a column of 10 mg of C18 (40 µm), eluted with methanol, in counter-current mode, and detected at 400 nm. The limit of detection was 0.1 µU mL-1 of protease with a reaction time of 30 min and the coefficient of variation (n = 2 or 3) were from 2.8 to 17%.
Enzymes, proteolytic Spectrophotometry

"Flow Injection Fluorimetric Determination Of Thiamine And Copper Based On The Formation Of Thiochrome"
Talanta 1992 Volume 39, Issue 8 Pages 907-911
T. Perez-Ruiz*, C. Martinez-Lozano, V. Tomas and I. Ibarra,

Abstract: Thiamine solution was injected into a stream of Cu2+ solution (2.8 mL min-1), which was then passed through a 1-m reaction coil, mixed with phosphate buffer solution (0.9 mL min-1) and passed through a second 1-m coil at 30°C. The thiochrome formed was detected fluorimetrically at 465 nm (excitation at 370 nm). Rectilinear calibration was obtained for 0.3 to 6.0 µg mL-1 of thiamine or, by injection of a standard volume of thiamine solution, for 0.5 to 5.0 µg mL-1 of Cu. The method was applied to the determination of thiamine in pharmaceuticals and of Cu in alloys and ores. Other vitamin B components interfered with the determination of thiamine, and other transition metals with that of Cu; I- interfered in both methods. The reaction, involving the oxidation of thiamine by copper(II) in basic solutions to fluorescent thiochrome, has been adapted to the determination of thiamine by flow injection analysis Linear calibration graphs are obtained between 0.30 and 6.02 µg/mL with a sampling rate of 50 samples/h and a relative standard deviation of 0.53%. This reaction has also been adapted to the determination of copper(II) over the range 0.5-5.0 µg/mL. The applicability of both methods for determination of thamine and copper is demonstrated by investigating the effect of potential interferences and by the anal. of real samples (pharmaceuticals for thiamine and ores and allows for copper).
Thiamine Copper Pharmaceutical Geological Fluorescence

"Flow Injection Analysis Of Serum Urea Using O-phthalaldehyde And Naphthylethylenediamine"
Talanta 1992 Volume 39, Issue 10 Pages 1233-1238
D. Narinesingh and A. Pope, T. T. Ngo

Abstract: The colorimetric reaction, modified by Lequang et al. (cf. Spectra Biol., 1987, 87, 44) was applied to the cited determination . Calibration graphs (at 517 nm) were rectilinear up to 51 mg L-1 of urea-N, when the flow injection manifold was operated at 42°C and 0.44 mL min-1. The recoveries were 95 to 99%. The within-day coefficient of variation were 0.5 to 2.2% and the between-day coefficient of variation were 2.1 to 3.9%. Some sulfur compounds and amino-acids interfered at concentration. >0.76 and >21 mg l-1, respectively. The results agreed well with those obtained by the free urease/Berthlot and the hospital (Abbott Bichromatic Analyser) method. An anal. procedure was developed for the determination of urea by flow injection analysis (FIA). The methodology is based on the color that develops (λmax, 517 nm) when urea reacts with o-phthalaldehyde in the presence of naphthylethylenediamine under acidic conditions. Calibration curves are linear up to 51 mg urea N/dL when the FIA manifold is operated at 42°C, utilizing 90 µL samples and a flow-rate of 0.44 mL/min. By manual injection up to 40 samples can be analyzed per h. Recovery yields ranged 95-99%. The within-day CV was 0.5-2.2% whereas the day-to-day CV was 2.1-3.9%. When applied to the anal. of urea in serum samples, excellent correlations (>0.998) are obtained when the FIA results are compared with those obtained for the same serum samples analyzed by the free urease/Berthelot's and the hospital method (employing the Abbot Bichromatic Analyzer). Interferences are observed with S compounds such as sulfanilamide (>0.76 mg/dL) as well as with many amino acids but at relatively high concentrations. (>21 mg/dL).
Urea Blood Serum Spectrophotometry

"Flow Injection Determination Of Chromium(III) By Pyrogallol Chemiluminescence"
Talanta 1993 Volume 40, Issue 1 Pages 75-80
Shigenori Nakano, Mitsunobu Fukuda and Shizuko Kageyama, Hideyuki Itabashi and Takuji Kawashima,

Abstract: A 1 mM or 0.1 M HCl carrier solution, 80 mM 3-(N-morpholino)propanesulfonic acid (chemiluminescence enhancer) in 6 mM EDTA - 0.3 M NH3 buffer, 0.1 mM pyrogallol solution and 6 mM IO4- solution were fed through the flow system at a rate of 0.7 mL min-1. A 321 µL portion of Cr(III) solution in HCl was injected into the carrier stream which was then mixed with the buffer solution and transferred to a heating coil in a water bath at 30°C. The pyrogallol and IO4- solution at 30°C were merged with the carrier in front of the flow cell. The emitted light resulting from the catalytic effect of Cr on the chemiluminescence system was monitored at 300 to 700 nm. The dynamic range for Cr(III) determination was 5 to 100 ng mL-1 at a sampling rate of 25 h-1. The detection limit was 1 ng mL-1 and the coefficient of variation (n = 10) was 2.2% for the determination of 20 ng mL-1 of Cr(III). The presence of EDTA masked interference from several ions; Co(II) interfered at levels above 25 ng mL-1. Total Cr could be determined by reducing Cr(VI) with SO32-.
Chromium(III) Chemiluminescence

"Flow Injection Determination Of 9,10-phenanthraquinone With Catalytic Photometric Detection"
Talanta 1993 Volume 40, Issue 3 Pages 405-407
Nobutoshi Kiba, Hiroshi Suzuki, Eiichi Goto and Motohisa Furusawa

Abstract: The flow injection procedure for determination of phenanthraquinone (I) is based on the catalytic effect of I on the reduction of 1,2-dinitrobenzene with formaldehyde. The carrier solution (3 M NaOH) and the reagent solution (3 mM 1,2-dinitrobenzene and 3 M formaldehyde in DMSO) are pumped through the FIA system. Aliquots of the sample solution are injected with a 10 µL loop and the mixture passed through a reaction coil at 60°C. The change in absorbance at 560 nm is monitored. The calibration graph is rectilinear over the range 5.0 x 10^-8 to 5.0 x 10^-6M. The interference of various quinones is investigated. The method is applied to the determination of I in photosensitive resin scraped from a 60 µm thick layer coating a circuit board prior to photoirradiation.
9,10-Phenanthraquinone Industrial Spectrophotometry

"Flow Injection Determination Of L-tyrosine In Serum With Immobilized Tyrosinase"
Talanta 1993 Volume 40, Issue 7 Pages 995-998
Nobutoshi Kiba, Hiroshi Suzuki and Motohisa Furusawa

Abstract: Serum was deproteinized by 5% sodium tungstate solution and 0.15 M H2SO4, filtered and a portion was injected into 0.2 M phosphate buffer solution of pH 7.2 (0.4 ml/min). The mixture passed through a separation column (4 cm x 4 mm) of Capcell 120 C18 and then through the enzymatic reactor (5 cm x 4 mm) containing monophenol monooxygenase immobilized on controlled pore glass (cf. Kiba et al., Anal. Chim. Acta, 1989, 224, 133). The effluent from the reactor was mixed with 30 mM 1,2-diphenylethylenediamine in 0.6 M HCl/ethanol (3:7) and the mixture passed through a reaction coil (1 m) held at 105°C and then through a cooling coil (10 cm) at 15°C, before measurement of the fluorescence at 480 nm (excitation at 350 nm) in a flow-through cell. The calibration graph was linear for 1-200 µM-L-tyrosine with a detection limit of 0.2 µM. Interference from cysteine or ascorbate was avoided. Recoveries of 70-985 µM-L-tyrosine from serum were 98-105%. Within- and between-day RSD were 1 and 1.8%, respectively, for 64 µM-L-tyrosine. Results agreed well with those obtained by an amino-acid analyzer..
Tyrosine Blood Serum Fluorescence

"Flow Injection Fluorimetric Determination Of Trimeprazine And Trifluoperazine In Pharmaceutical Preparations"
Talanta 1993 Volume 40, Issue 9 Pages 1361-1365
T. P&eacute;rez-Ruiz*, C. Mart&iacute;nez-Lozano, V. Tom&aacute;s and C. Sidrach de Cardona,

Abstract: The flow injection system described is based on the oxidation of trimeprazine (I) and trifluoperazine (II) by Ce(IV) and the fluorimetric determination of Ce(III). Finely ground tablets were extracted by water with ultrasonic mixing and the resulting suspension was filtered. A 158 µL portion of the filtrate was injected into a stream (0.8 ml/min) of 1 mM Ce(IV) in 1 M H2SO4 at 30°C. After passing through the reaction coil (30 cm x 0.5 mm) the Ce(III) was detected fluorimetrically at 355 nm (excitation at 255 nm). The calibration graphs were rectilinear for 0.2-10 µM-I and II with RSD (n = 10) of 0.8-1.2% with a recovery of 96-104%. The sampling rate was 60 samples/h. The tolerance limits for various foreign substances are listed. Ascorbic acid, acetylsalicylic acid and Na2SO3 interfere.
Trimeprazine Trifluoperazine Cerium(3+) Pharmaceutical Fluorescence

"Multi-data Treatment Applied To The Simultaneous Resolution Of Catechol-resorcinol Mixtures By Kinetic Enzymic Processes"
Talanta 1993 Volume 40, Issue 11 Pages 1601-1607
E. G&oacute;mez, A. Cladera, J. M. Estela and V. Cerda*,

Abstract: Mixtures of catechol and resorcinol were analyzed by oxidation with H2O2 and peroxidase in a stopped-flow reversed-flow injection system. The FIA manifold merged a stream of analyte solution with 0.03% H2O2 solution and 0.1 M phosphate buffer solution of pH 7 (all flow rates 0.7 ml/min). After passing through a reaction loop (0.5 m x 0.5 mm i.d.) at 35°C, the mixture was merged with a carrier stream (0.7 ml/min) of 0.1 M phosphate buffer solution of pH 7 at 35°C. A 100 µL volume of peroxidase (7.68 µg/ml) was injected into the carrier stream and after 15 s the flow was halted. The reaction was monitored from 250-550 nm at 1 reading/s. The data was processed using DARRAY and MULTI3 computer programs. The calibration graphs of initial reaction rate vs. concentration, prepared using a set of five multiple standards, were linear for 50-150 µM-catechol and 30-180 µM-resorcinol. The sampling frequency was 60/h.
Catechol Resorcinol Spectrophotometry

"Generic FIA System For Determination Of Enzyme Activities: Assay Of Cellulase"
Talanta 1993 Volume 40, Issue 12 Pages 1891-1897
Elo H. Hansen and Allan Jensen

Abstract: A general method was devised for systems where the enzyme reaction was slow and the detection reaction for the products was even slower. The two parts of the reaction were completely separated, only being in contact via the injection valve allowing separate optimization of the two stages. The method was exemplified by the determination of cellulase activity. The 50 mL reaction vessel containing 24 mL of 4% carboxymethylcellulose substrate in 10 mM phosphate buffer of pH 7 (24 ml) was heated at 40°C and 1 mL of enzyme solution at 40°C was added to start the reaction. The mixture was continuously pumped (1.75 ml/min) in a closed loop. At intervals 50 µL portions were taken and analyzed, after mixing with a water carrier solution (0.88 ml/min) and an alkaline p-hydroxybenzoylhydrazide reagent containing a bismuth tartrate catalyst (0.88 ml/min). The mixture was held in a coil at 77°C for 90 s and the absorbance of the reducing sugars liberated was measured at 410 nm. Absorbances were recorded over a 22 min reaction period and the initial slopes were plotted against enzyme concentration. Calibration graphs were linear for 0.1-2 iu/ml of sample solution; RSD were 3-12%.
Enzyme, cellulase Spectrophotometry

"Chemiluminescence Detection Of Sodium Nitroprusside Using Flow Injection Analysis"
Talanta 1994 Volume 41, Issue 10 Pages 1683-1688
Abdulrahman A. Alwarthan,

Abstract: Sodium nitroprusside (I) was injected into a stream of 0.01 M luminol in 0.1 M carbonate buffer of pH 10.4 (2.5 ml/min) which passed through a reaction coil (150 cm x 0.8 mm i.d.) in a water bath at 70°C. The stream merged with a 1 mM H2O2 stream (2.5 ml/min), mixed in a PTFE T-piece and passed into a coiled glass flow cell (5 turns; 1.3 mm i.d.). Chemiluminescence was detected by a photomultiplier tube. The calibration graph was linear for 0.05-10 µg/ml of I with a detection limit of 0.05 µg/ml and RSD (n = 10) of 1.18% for 2.5 µg/ml. The effects of foreign cations and other excipients found in pharmaceuticals are tabulated and discussed. The method was used for the determination of I in pharmaceutical preparations.
Nitroprusside Pharmaceutical Chemiluminescence

"Multistep Determination Of Enzyme Activity By Flow Injection And Sequential-injection Analysis. Assay Of Amyloglucosidase"
Talanta 1994 Volume 41, Issue 11 Pages 1881-1893
Elo Harald Hansen, Bodil Willumsen, Solveig K. Winther and Helle Drab&oslash;l,

Abstract: A reactor vessel containing 27.8 mM maltose substrate in 5 mM acetate buffer of pH 4.3 was heated to 37°C and amyloglucosidase (glucan 1,4-α-glucosidase) was added with stirring. Samples were withdrawn at preset times into a previously described FIA system (Hansen and Jensen, Ibid., 1993, 40, 1891) for spectrophotometric detection. Glucan 1,4-α-glucoside was also assayed using a sequential injection analysis (SIA) system. The SIA system comprised a peristaltic pump, a 10 port electrically actuated multi-position directional valve and a computer. The water carrier solution, 50 g/l maltose solution in 0.02 M acetate, sample solution and glucose dehydrogenase reagent were placed around the valve along side a narrow glass vessel mixing chamber with a stirring bar in a thermostatted water bath at 37°C. The flow rate was 1.2 ml/min and detection was by diode-array spectrophotometry. Both FIA and SIA allowed two mutually incompatible reactions to be completely separated.
Amyloglucosidase Biological Spectrophotometry

"Fluorimetric Flow Injection Analysis Of Total Amounts Of Aldehydes In Auto Exhaust Gas And Thermal Degradation Emission Gas With Cyclohexane-1,3-dione"
Talanta 1996 Volume 43, Issue 6 Pages 859-865
Tadao Sakaia,*, Hideki Nagasawaa and Harumitsu Nishikawab

Abstract: Car exhaust gases and emission gases from the thermal degradation of polymers were collected by drawing through methanol. The methanol solution was injected into a carrier stream of water and the carrier stream merged with a reagent stream of 0.02% cyclohexane-1,3-dione in aqueous ammonium acetate/acetic acid buffer of pH 5 (0.75 ml/min). The resultant stream passed through a reaction coil (7 m x 0.5 mm i.d.) at 70°C, then through a cooling coil (2 m x 0.5 mm i.d.) at 10°C to a fluorescence detector for measurement of 452 nm (excitation at 376 nm). Calibration graphs were linear from 100-1000 ppb aldehydes with a detection limit of 30 ppb and RSD (n = 10) of 1.5% for 500 ppb formaldehyde. Sample frequency was 30 samples/h.
Aldehydes, total Exhaust Automobile Polymer Fluorescence

"Flow Injection Systems For Determination Of Trace Manganese In Various Salts By Catalytic Photometric Detection"
Talanta 1996 Volume 43, Issue 6 Pages 963-969
Takeshi Yamanea,* and Kazuo Koshinoa

Abstract: Solar salt was dissolved in water and filtered for soluble Mn determination and in water, 2 M HCl and 1.5% H2O2 with heating for 5-10 min followed by filtering for determination of total Mn. The sample containing 0.85 M NaCl was injected into a carrier stream (0.8 ml/min) at water. The stream merged with reagent streams (0.5 ml/min) of 0.26 mM 3,4-dihydroxybenzoic acid/0.75% H2O2 and 1 M sodium carbonate solution. The merged streams passed through a reaction coil (5 m x 0.5 mm i.d.) in a water bath at 40°C and the absorbance was measured at 480 nm. The same system was also used with an online separation step. The sample was injected into a carrier stream of 0.15 M sodium tartrate/4.5 mM tartaric acid/0.3 M NaCl which passed to a borosilicate glass column (7 cm x 4 mm i.d.) packed with 15.5 µm strong cation exchange resin before merging with the reagent streams as above. Calibration graphs were linear for 2-15 ppb Mn and 0-15 ppb Mn in the absence and presence of online separation, respectively, with corresponding detection limits of 2 ppb and 0.5 ppb. RSD (n = 5) was 0.9% for 8 ppb Mn without online separation and 1.4% (n = 5) for 7 ppb Mn.
Manganese Inorganic compound Ion exchange Spectrophotometry

"Selectivity Enhancement For Glutamate With A Nafion/glutamate Oxidase Biosensor"
Talanta 1996 Volume 43, Issue 7 Pages 1157-1162
Shengtian Pan and Mark A. Arnold*

Abstract: Response properties and selectivity are reported for glutamate biosensors constructed with a film of Nafion between the platinum anode and a layer of immobilized glutamate oxidase. The effects of enzyme loading, sample pH and temperature are established. Operation at pH 7.8 and 37°C results in linearity up to 800 µM and a limit of detection of 0.3 µM. Nafion enhances selectivity for glutamate over test species that include ascorbic acid, uric acid and acetaminophen. Selectivity enhancement was greater over the anionic interferences because of electrostatic repulsion and the extent of this enhancement depends on the thickness of the Nafion layer. Even under ideal conditions, some interfering signal is observed when glutamate levels are ten-times less than ascorbate.
Glutamate Sensor Electrode Electrode

"Catalytic Flow Injection Determination Of Copper At Nanogram Levels By Using Color Formation Of N-phenyl-p-phenylenediamine With M-phenylenediamine In The Presence Of Pyridine And Ammonia As Activators"
Talanta 1997 Volume 44, Issue 5 Pages 765-770
Shigenori Nakanoa,*, Keiko Nakasoa, Kazunori Noguchia and Takuji Kawashimab

Abstract: Sample (215 µL) was injected into a carrier stream of 0.1 M HCl, into which streams (1 ml/min) of 0.5 M H2O2, 1 mM N-phenyl-p-phenylenediamine hydrochloride/0.5% Tween 80 and 3 mM phenylenediamine dihydrochloride/0.5 M NH3/0.2 M pyridine/ 2 mM citric acid were pumped. The flow passed through a reaction coil (8 m x 0.5 mm i.d.) at 55°C and the absorbance of the dye formed was measured at 620 nm. The calibration graph was linear from 0.1-2 ng/ml Cu(II) and the detection limit was 0.05 ng/ml. RSD (n = 10) at 1 and 2 ng/ml Cu(II) were 2.4% and 1.6%, respectively. Sample throughput was 30/h. Tolerance limits for interfering ions are tabulated. The method was applied to natural waters.
Copper Environmental Spectrophotometry

"A Sensitive Flow Injection Method For Determination Of Trace Amounts Of Nitrite"
Talanta 1998 Volume 45, Issue 6 Pages 1247-1253
M. F. Mousavi*, A. Jabbari and S. Nouroozi

Abstract: A new sensitive color reaction for nitrite determination is presented. In acidic medium, nitrite was reacted with safranine to form a diazonium salt which caused the reddish-orange dye color of the solution to change to blue. The carrier stream, into which the sample solution was injected, was doubly distilled water. The reagent solution stream, which contained safranine dye, hydrochloric acid and potassium chloride, was mixed with the carrier in a 3 m length of silicon tubing (bore 0.5 mm) maintained at 30°C in a thermostatic bath. The absorbance intensity was measured at 520 nm. The detection limit was 20 ng/mL and the RSD% of 20 injections of 1 µg/mL of nitrite was 0.65%. Anal. can be done at a rate of up to 30 h-1. Under the optimum conditions in the concentration. range of 30-4000 ng/mL of nitrite ion, a linear calibration graph was obtained (r = 0.9999). The method was applied successfully to the determination of nitrite in sausages.
Nitrite Food Spectrophotometry

"Development Of A System With Enzyme Reactors For The Determination Of Fish Freshness"
Talanta 1998 Volume 47, Issue 2 Pages 335-342
M. -A. Carsol and M. Mascini*

Abstract: A continuous system for the determination of fish freshness with double enzyme reactors was developed and applied to the determination of the freshness indicator K K = 100(HxR + Hx)/(IMP + HxR + Hx), where IMP, HxR and Hx are Inosine monophosphate, Inosine and Hypoxanthine, respectively. The system was assembled with a three electrode screen-printed element (graphite as working electrode, silver as counter and silver, silver chloride as reference electrode) placed in a flow cell, a sample injection valve and two enzyme reactors. The determination of the total amt. of HxR and Hx is realized by flowing the sample through two reactors in series: one reactor was packed with nucleoside phosphorylase (Np) and the other with xanthine oxidase (XO) immobilized on aminopropyl glass. Similarly, the other term of the equation was evaluated by flowing through the two reactors the sample treated by Alkaline phosphatase (AlP) for 5-10 min at 45°C. One assay could be completed within 5 min. The system for the determination of fish freshness was reproducible within 2-3% (n = 4). The immobilized enzymes were fairly stable for at least three months at 4°C. More than 200-300 samples could be analyzed in about one month by using these enzyme reactors provided the disposable screen-printed electrode should be changed every 30-40 real samples. The results obtained suggest that the proposed sensor system provides a simple, rapid and economical method for the determination of fish freshness (K). We applied the present system with two reactors for the determination of K values in fish samples and compared the results with those obtained by the XO-reactor. Correlation factor and regression line between the two methods were 0.992 and Y = -3.14+1.03X respectively. We concluded that the present flow injection analysis (FIA) system with XO and Np reactors was suitable as a simple, easy to handle and reliable instrument for quality control in the fish industry.
Inosine monophosphate Inosine Hypoxanthine Marine Electrode Amperometry Electrode

"Dual-phase Gas-permeation Flow Injection Thermometric Analysis For The Determination Of Carbon Dioxide"
Talanta 1998 Volume 47, Issue 3 Pages 711-717
Shan-jun Liu and Matthieu Tubino*

Abstract: A flow injection configuration based on a dual-phase gas-permeation system from a liquid donor to a gas acceptor stream with a thermistor flow-through detector is proposed for the direct anal. of the gas in the acceptor. This system was applied for the determination of CO2 (as carbonate) using the following chemical reaction: CO2(g) + 2NH3(g) + H2O(g)=(NH4)2CO3(s), with a linear response from 1 x 10^-3 to 50 x 10^-3 mol 1-1 of CO32-. CO2 was produced in the liquid donor and permeated into the gaseous acceptor stream of air/H2O vapor. The detection limit is 1 x 10^-3 mol 1-1 of carbonate, and a sampling frequency of 60 h-1 is achieved with a relative standard deviation of 4.1% for replicate injections. The dual-phase gas-permeation flow injection manifold, along with the membrane and phase sepns., as well as the chemical reaction, provides enhanced selectivity when compared with the system employing a liquid acceptor stream, as serious interferents in this system, for instance, acetate and formate, among others, do not interfere in the proposed system.
Carbon dioxide Thermistor

"Online Bromimetric Determination Of Phenol, Analine, Aspirin, And Isoniazid Using Flow Injection Voltammetry"
Analyst 1983 Volume 108, Issue 1288 Pages 840-846
Arnold G. Fogg, Md. Ashraf Ali and Mohamed A. Abdalla

Abstract: Bromine was liberated by the interaction of 1 µM to 1 mM KBrO3 and 0.01 M KBr in an eluent of 1 M HCl with use of the flow injection system previously described (Ibid., 1982, 107, 1040). The reduction signal for Br was recorded with a vitreous-carbon electrode maintained at +0.38 V vs. the SCE Two methods of analysis were used. In the first, a 0.1 mM solution of the analyte was injected, and, after passage through a 1-m reaction coil, unconsumed Br was monitored. Aspirin was hydrolyzed before determination. The method was rapid and more convenient than existing titrimetric methods for certain applications. In the second method, a higher concentration. of HCl was used with a 4-m coil at 70°C and 2-m coil at room temperature This procedure was also rapid, but calibration graphs were curvilinear. In both procedures, re-calibration was essential after polishing of the vitreous-carbon electrode; the position of the electrode in the detector cell also affected the magnitude of the signal. The coefficient of variation (3 to 10 measurements) was generally <3% for 10 µM to 0.1 mM levels of analyte.
Phenol Aniline Aspirin Isoniazid Voltammetry Electrode

"Online Oxidation Of Chromium(III) To Chromium(VI) For Use With The Flow Injection Analysis Technique"
Analyst 1984 Volume 109, Issue 5 Pages 645-647
Jo&atilde;o Carlos de Andrade, Julio Cesar Rocha and Nivaldo Baccan

Abstract: The extent of oxidation of Cr(III) to Cr(VI) was followed by the 1,5-diphenylcarbazide spectrophotometric method (Storgaard Joergensen and Regitano, Anal. Abstr., 1980, 39, 4G17) with use of a flow injection analysis system. The most convenient oxidant was cerium(IV) sulfate under dynamic conditions. Optimum results were obtained at 45°C with 0.025% Ce(IV) solution in 70 mM H2SO4 with Cr(III) solution containing 30 mM H2SO4. Experimental details are included for this oxidation method for use before spectrophotometric determination of total Cr.
Chromium(III) Spectrophotometry

"Determination Of Silicon In Soil Extracts By Flow Injection Analysis"
Analyst 1985 Volume 110, Issue 2 Pages 177-180
Ole K. Borggaard and S&oslash;ren Storgaard J&oslash;rgensen

Abstract: Flow injection analysis was used for spectrophotometric determination (at 35 h-1) of dissolved Si in complex aqueous media, e.g., soil extracts. Molybdenum blue is formed by the reduction of β-molybdosilicate by ascorbic acid and measured at 816 nm. Determination must be performed at ~80°C to accelerate the formation of β-molybdosilicate and the decomposition of molybdophosphate, formed in phosphate-containing solution. The detection limit is 30 ng mL-1 of SiO2 with a coefficient of variation of 2%. EDTA, Al, Fe, and P do not interfere at naturally occurring levels in soil extracts diluted to contain <1.0 µg mL-1 of SiO2; dithionite requires oxidation by aeration before Si determination. Results for Si in seven soil samples by flow injection analysis were in close agreement with those by a manual photometric procedure.
Silicon Environmental Sample preparation Spectrophotometry

"Simultaneous High Performance Liquid Chromatographic Determination Of Monensin, Narasin And Salinomycin In Feeds Using Post-column Derivatization"
Analyst 1985 Volume 110, Issue 11 Pages 1283-1287
W. John Blanchflower, Desmond A. Rice and John T. G. Hamilton

Abstract: Samples (20 g) are extracted with methanol (50 ml) and the solution are analyzed on a column (25 cm x 4.6 mm) of Partisil 5ODS-3 reversed-phase material, with methanol - water - anhydrous acetic acid (940:59:1) as the mobile phase (0.7 mL min-1). The eluate is mixed with a solution comprising 10% vanillin and 2% H2SO4 in methanol, in a reaction coil maintained at 70°C; the absorption of the color produced is measured at 520 nm. The limits of detection are 0.25 mg kg-1 for monensin and 0.5 mg kg-1 for narasin and salinomycin with recoveries ranging from 95 to 108% at concentration. levels between 2.5 and 100 mg kg-1. The coefficient of variation are between 0.91 and 3.6% (n = 5 or 10) in the range 3.81 to 99.37 mg kg-1.
Monensin Narasin Salinomycin Feed HPLC Spectrophotometry

"Catalytic Determination Of Manganese At Ultratrace Levels By Flow Injection Analysis"
Analyst 1986 Volume 111, Issue 1 Pages 69-72
S. Maspoch, M. Blanco and V. Cerd&aacute;

Abstract: The catalytic effect of Mn(II) on the oxidation of succinimide dioxime in alkaline medium was used for determination of Mn(II) by flow injection analysis with photometric detection at 695 nm. Variation of the reaction temperature between 25°C and 45°C allows the determination range to be extended from 0.2 to 1300 ng mL-1, with a sampling frequency of 45 h-1 and a coefficient of variation of 1.3 to 1.0%. Injection of the sample in a flow of EDTA solution overcomes most interference. Interference by Co(II), Fe(II) and Mg(II) was investigated. The method was used to determine Mn in reagent-grade ZnO and HClO4 and in powdered coffee and rice.
Manganese(II) Rice Powder Inorganic compound Inorganic compound Spectrophotometry

"Automatic Spectrophotometric Determination Of Amyloglucosidase Activity Using P-nitrophenyl-α-D Glucopyranoside And A Flow Injection Analyzer"
Analyst 1986 Volume 111, Issue 8 Pages 927-929
Kaj Andr&eacute; Holm

Abstract: The method is based on the hydrolysis of 4-nitrophenyl-α-D-glucopyranoside(I) by the cited enzyme, glucan 1,4-α-glucosidase(II), and spectrophotometric determination of the 4-nitrophenol released. The sample (30 µL) is injected into a water carrier stream (1.4 mL min-1), which is mixed with a reagent stream (0.53 mL min-1) containing 2 g L-1 of I in 0.1 M acetate buffer (pH 4.3). The solution is incubated for 20 s at 50°C, passed through a reaction coil at 60°C, and mixed with 0.1 M Na2CO3 (0.53 mL min-1) before the absorbance is measured at 400 nm. Similar procedures have been developed for the determination of α-L-arabinofuranosidase and α-galactosidase activity with 4-nitrophenyl-α-L-arabinofuranoside and 4-nitrophenyl-α-D-galactopyranoside as chromophores, respectively.
Amyloglucosidase Spectrophotometry

"Spectrophotometric Determination Of Trace Amounts Of Nitrite Based On The Nitrosation Reaction With N,N-Bis(2-hydroxypropyl Aniline And Its Application To Flow Injection Analysis"
Analyst 1987 Volume 112, Issue 9 Pages 1261-1263
Shoji Motomizu, Shi Chen Rui, Mitsuko Oshima and Kyoji T&ocirc;ei

Abstract: Sample solution (280 µL) was mixed with reagent (0.02 M in concentrated HCl; 2 ml) and 1 M HCl (1 ml), and diluted to 25 mL. After 30 min at 25°C, the absorbance was measured at 500 nm (e = 20,000). The calibration graph was rectilinear from 5 to 50 µM-NO2-. The effects of temperature of heating bath, length of reaction coil, concentration. of reagent and acid, flow rate and sample size were studied. The method was applied in the determination of NO2- by flow injection analysis (manifold described with diagram). In the flow injection method, the reaction was accelerated by heating the coil to 80°C in a water bath, then cooling the solution before determination. The sampling rate was 50 h-1.
Nitrite Spectrophotometry

"Determination Of Glucose Using Flow Injection With A Carbon Fiber Based Enzyme Reactor"
Analyst 1987 Volume 112, Issue 10 Pages 1433-1435
K. P. Ang, H. Gunasingham, B. T. Tay, V. S. Herath, P. Y. T. Teo, P. C. Thiak, B. Kuah and K. L. Tan

Abstract: A reactor of immobilized glucose oxidase(I) covalently coupled to a bundle (~105) of carbon fibers by the method described by Bourdillon et al. (J. Am. Chem. Soc., 1980, 102, 423) is used with a wall-jet detector in the flow injection analysis of H2O2 produced by the enzymatic reaction of I with glucose. The working platinum electrode is operated at +0.7 V vs. silver - AgCl, the max. response being achieved at 1.45 mL min-1 with phosphate buffer at pH 7.4. The response increases with increase in temperature of the reactor. Response is rectilinear from 3 to 30 mM glucose. The coefficient of variation is 2% (n = 100).
Glucose Amperometry Electrode Electrode

"Rapid, Miniaturized Procedure For The Determination Of Glucose Based On Flow Injection Principles"
Analyst 1987 Volume 112, Issue 11 Pages 1565-1568
Jun'-ichi Toei

Abstract: The proposed flow injection method is based on the Wako glucose C enzymatic test kit procedure (Wako Pure Chemicals, Osaka, Japan). The reagent (70 µL) is introduced into a variable-volume mixing device (described and illustrated) that is placed within the injection loop of a six-port valve. The whole unit is heated to 40°C in a water bath. The sample solution (1 µL) is injected into the mixing device and, after 1 min, the reaction mixture is transferred to the water carrier stream (1 mL min-1) and the absorbance is monitored at 535 nm in a flow-through spectrophotometer. The calibration graph is rectilinear up to 5 g L-1 of glucose and the coefficient of variation at 2 and 5 g L-1 are 1.01 and 3.34%, respectively (n = 7). Results for two samples of serum were in excellent agreement with those obtained with the manual Wako test kit.
Glucose Blood Serum Clinical analysis Spectrophotometry

"Continuous-flow Determination Of Low Concentrations Of Ammonium Ions Using A Gas Dialysis Concentrator And A Gas Electrode Detector System"
Analyst 1988 Volume 113, Issue 1 Pages 113-115
Hirokazu Hara, Atsushi Motoike and Satoshi Okazaki

Abstract: A gas-dialysis unit based on a micro-porous PTFE membrane (cf. Fraticelli and Meyerhoff, Anal. Chem., 1981, 53, 992) is described. The recipient buffer system is 0.01 M K H phthalate in which the diffused NH3 is converted into NH4+, which is detected by an NH3-selective electrode (Orion 95-12) after addition of NaOH. The concentration. factor is ~10 between 11°C and 29°C. The response is rectilinear for three decades up to 1000 µg L-1 with a limit of detection of 3 µg L-1 of N. The method is applied to purified and natural waters.
Ammonium Water Environmental Electrode

"Flow Injection Determination Of Drugs By Specific Detection Of Carboxylic Acids"
Analyst 1988 Volume 113, Issue 11 Pages 1673-1675
Toshifumi Takeuchi, Yozo Kabasawa, Rikizo Horikawa and Takenori Tanimura

Abstract: A variety of carboxylic acid drugs were determined. A portion, containing ~0.25 mmol of drug, of the powder obtained from 20 tablets or capsules was extracted with ethanol or water, the extract was filtered, and the filtrate was analyzed in a flow injection system in which it was treated with 0.02 M 2-nitrophenylhydrazine in 0.2 M HCl and 0.05 M 1-ethyl-3-(3-dimethylaminopropyl)carbodi-imide in ethanolic 4% pyridine in the first reaction coil (10 m x 0.5 mm) at 60°C and with 1.5 M NaOH in a second coil of the same dimensions and temperature After cooling to 30°C in a third coil (1 m x 0.5 mm) the absorbance was measured at 540 nm. Satisfactory results were obtained for aspirin, ibuprofen, dehydrocholic acid, nicotinic acid and tranexamic acid, with recoveries of 99.9 to 103.4% and coefficient of variation (n = 10) of 0.8%.
Drugs Aspirin Ibuprofen Dehydrocholic acid Nicotinic acid Tranexamic acid Pharmaceutical Pharmaceutical Spectrophotometry

"Automated Flow Injection Measurement Of Photographic Dyes In Gelatin At Elevated Temperatures"
Analyst 1990 Volume 115, Issue 11 Pages 1407-1410
Richard H. Taylor, Gregory D. Clark, Jaromir Ruzicka and Gary D. Christian

Abstract: Photographic dyes in a gelatin matrix were determined by automated flow injection analysis, by using the split zone - gradient chamber dilution technique (Clark et al., Anal. Chem., 1989, 61, 1773), DMSO as carrier solvent and direct spectrophotometric detection (at 553 nm for a magenta dye and 459 nm for a yellow dye). The matrix was kept liquid by placing the apparatus in an incubator oven at 41°C to 44°C. With dilution times of 60 and 30 s for the magenta and yellow dyes, respectively, calibration graphs were rectilinear for 60 and 100 g l-1, respectively. The coefficient of variation was 2% for dilutions of 2000-fold. Results agreed to within 5% with those of a manual method.
Dyes, photographic Organic compound Spectrophotometry

"Indirect Determination Of Chloride By Gas Diffusion Flow Injection With Amperometric Detection"
Analyst 1991 Volume 116, Issue 1 Pages 49-52
Snezana D. Nikolic Emil B. Milosavljevic, James L. Hendrix and John H. Nelson

Abstract: A flow injection manifold was designed for the cited determination (diagram given). A continuous flowing donor stream containing Cl- in 3 M H2SO4 and saturated KMnO4 solution diffused through a Nafion membrane into a 10 mM H2SO4 acceptor solution and subsequently to a flow-through amperometric cell (maintained at 30°). Measurements were made with a three-electrode system consisting of Pt working and counter electrodes and a Ag - AgCl reference. The applied optimum potential was +0.30 V. The calibration graph was rectilinear up to 10 mM of Cl- and the coefficient of variation was 1% for 2 mM (n = 9). The sampling rate was 30 h-1. At a cell temperature of 50°C and an acceptor solution of 5 M H2SO4, the detection limit was 0.1 µM. The effects of interferents are discussed. The method was applied to drinking water.
Chloride Water Amperometry Electrode Electrode

"Studies On Enzyme Electrodes With Ferrocene And Carbon Paste Bound With Cellulose Triacetate"
Analyst 1991 Volume 116, Issue 5 Pages 459-462
S. K. Beh, G. J. Moody and J. D. R. Thomas

Abstract: A ferrocence-based chemically modified electrode was prepared by mixing carbon powder and ferrocene, and the mixture was bound with 20% cellulose triacetate (1+2+1 m/m) in 1,2-dichloroethane. The mixture was packed into the well of an electrode holder. A small drop of the cellulose triacetate solution was placed on the electrode surface to form a protective covering. The electrode was oven-dried for 24 h at 50°C and smoothed with emery paper. Glucose oxidase immobilized on to nylon net (Ibid., 1989, 114, 1421) was placed over the electrode which was then housed in a three-electrode Stelte micro-cell modified for flow injection, and further modified by introducing a viscose acetate exclusion membrane between the outermost nylon-enzyme mesh and the ferrocence - carbon paste layer. Glucose was determined amperometrically by monitoring the product of H2O2 enzymolysis at +160 mV vs. Ag - AgCl. From 0.01 to 70 mM glucose was determined and the lifetime of the electrode was >2 years with intermittent use. There was minimum interference from ascorbic acid. The detection range was extended to 100 mM glucose by covering the electrode surface with an exclusion membrane. A simplex optimization procedure was used in evaluating electrodes without the use of an exclusion membrane.
Amperometry Electrode Electrode

"Amperometric Enzyme Electrode For Theophylline"
Analyst 1991 Volume 116, Issue 10 Pages 997-999
Joseph Wang, Eithne Dempsey, Mehmet Ozsoz and Malcolm R. Smyth

Abstract: An amperometric biosensor for theophylline, based on the recently isolated enzyme theophylline oxidase, is described. The enzyme is entrapped, together with a ferricytochrome C cofactor, within a polymeric (Nafion) coating. The anodic detection (at +0.4 V versus Ag-AgCl) is facilitated by the addition of a redox-mediating hexacyanoferrate(III) ion. The influence of various experimental variables is described. The limit of detection is 2 x 10^-6 mol L-1 theophylline, with linearity prevailing up to 3 x 10^-4 mol L-1. The fast response and wash times permit rapid flow injection measurements, with a frequency of 180 samples h-1 and a relative standard deviation of 3.0-4.0%. Prospects of using this electrode for clinical diagnostics are discussed. The cited enzyme electrode was prepared by applying a 5 µL portion of a 1% Nafion - theophylline oxidase - 30 µM-ferricytochrome C mixture (details given) to the surface of a Pt-disc electrode. The layer was dried at 35°C using a heat gun, a second 5 µL portion of the mixture was added and the resulting film was covered with 5 µL of ethanolic 1% Nafion solution Theophylline (I) was determined at +0.4 V vs. Ag - AgCl in the presence of 1 mM hexacyanoferrate(III) and at pH 5.4 to 6.9. The calibration graph was rectilinear for 0.3 mM I; the detection limit was 2 µM. Under flow injection conditions, the sample throughput was 180 h-1, the response was rectilinear for 3 mM I and the detection limit was 10 µM. Glucose, paracetamol and caffeine showed negligible interference.
Theophylline Amperometry Electrode Electrode Sensor

"Spectrophotometric Determination Of Biacetyl In Distillates Of Wine By Flow Injection"
Analyst 1992 Volume 117, Issue 8 Pages 1343-1346
Gloria del Campo and M. Carmen Lajo

Abstract: Biacetyl (I) was determined in wine by its reaction with 1-naphthol and creatine in alkaline medium. Reaction with the principal interferent, acetoin, was relatively slower so optimization of the flow injection conditions was used to increase the selectivity for I. A portion of wine steam distillate diluted with water was injected into a stream of 1-naphthol in NaOH and merged with a stream of creatine in NaOH at 0.4 mL min-1. The 280 cm long reaction coil was placed in a water bath at 35°C. The absorbance of the solution was measured at 520 nm and the sampling rate was 30 h-1. The calibration graph was rectilinear up to 10.0 µg mL-1 with coefficient of variation of 0.7 and 0.4% for 1.0 and 5.0 µg mL-1 of I standard, respectively (n = 10). For wine distillates, the coefficient of variation of the method was 2.7 to 3.3% and the recovery of I was 98 to 104%. The reaction of biacetyl with 1-naphthol (40 g/L) and creatine (6 g/L) in an alkaline medium was used to develop a flow injection method for the determination of biacetyl. The fact that biacetyl reacts comparatively faster than acetoin was exploited to minimize interference by acetoin; the optimum experimental conditions for increasing the selectivity were: temperature, 35°C; reaction coil length, 280 cm; flow rate, 0.4 mL/min; sample volume, 220 mm3. Under these conditions, the relationship between the peak height (absorbance), measured at 520 nm, and the concentration of biacetyl was linear up to 10.0 µg mL-1 with a relative standard deviation (RSD) of 0.74 and 0.37% for 1.0 and 5.0 µg mL-1 biacetyl standards (n = 10), respectively. The sampling rate was 30/h. When the method was applied to the determination of biacetyl in wine, after a separation step for biacetyl by steam distillation, the RSD was 2.7-3.3%, and the results were in good agreement with those obtained by a conventional spectrophotometric method. Recovery of biacetyl from wine samples spiked with 1.65 and 3.30 µg biacetyl/mL averaged 100.2%, with no serious interference from acetoin.
Biacetyl Wine Spectrophotometry

"Spectrophotometric Determination Of Quaternary Ammonium Salts By A Flow Injection Method Coupled With Thermochromism Of Ion Associates"
Analyst 1992 Volume 117, Issue 2 Pages 211-214
Tadao Sakai

Abstract: A selective and rapid spectrophotometric method has been established for the determination of cetylpyridinium and benzalkonium chlorides by a flow injection technique coupled with ion-pair extraction and thermochromism of the ion associates. Selectivity can be enhanced because the absorbance of ion association compounds formed between co-existing amines and the anionic tetrabromophenolphthalein ethyl ester disappears at elevated temperatures in the flow cell. Accordingly, interferences due to amine associates can be eliminated by absorbance measurement at 45°C. The sample throughputs were 60 h-1 for cetylpyridinium and 50 h-1 for benzalkonium. The calibration graphs were linear in the range 5 x 10^-7-2 x 10^-6 mol dm-3 for both compounds. The relative standard deviations (n= 5) for 1 x 10^-6 mol dm-3 cetylpyridinium and benzalkonium at 45°C were both 2.1%. The proposed method was used for the selective and rapid determination of quaternary ammonium compounds in pharmaceuticals.
Quaternary Ammonium Ion Spectrophotometry

"High Performance Liquid Chromatographic Determination Of 5-hydroxyindoles By Post-column Fluorescence Derivatization"
Analyst 1993 Volume 118, Issue 2 Pages 165-169
Junichi Ishida, Ryuji Iizuka and Masatoshi Yamaguchi

Abstract: A TSKgel ODS-80Tm column (15 cm x 4.6 mm; particle size 5 µm) was used with acetonitrile - 10 mM acetate buffer at pH 4.7 (1:19) as mobile phase (1.0 mL min-1) to separate the biogenic compounds 5-hydroxytryptophan (I), 5-hydroxytryptamine, 5-hydroxyindol-3-ylacetic acid (II), 5-hydroxytryptophol and N-acetyl-5-hydroxytryptamine (III). The eluate was reacted with 0.5 mL min-1 of a solution of 20 mM benzylamine and 3.0 mM KFe(CN)62- in acetonitrile - 25 mM borate buffer at pH 10 (1:1) in a PTFE coil (7 m x 0.5 mm) at 70°C and passed through a PTFE cooling coil (0.5 m x 0.5 mm) in ice-H2O before detection by fluorescence measurement with excitation at 345 nm and emission at 481 nm. Calibration graphs were rectilinear for up to at least 2.5 nmol of each amine; the detection limits ranged from 140 fmol of I to 470 fmol of III. The method was also used to determine II in urine samples from healthy and carcinoid human subjects (procedure detailed). A selective and sensitive high performance liquid chromatographic method with post-column fluorescence detection has been developed for the determination of 5-hydroxyindoles. Five biogenic 5-hydroxyindoles (5-hydroxytryptophan, 5-hydroxytryptamine, 5-hydroxyindol-3-ylacetic acid, 5-hydroxytryptophol and N-acetyl-5-hydroxytryptamine) were separated by isocratic elution on a reversed-phase column, TSKgel ODS-80Tm, and then converted into fluorescent derivatives by post-column reaction with benzylamine and potassium hexacyanoferrate(III) reagents. The detection limits (signal-to-noise ratio = 3) for the indoles were in the range 140-470 fmol per injection volume (100 µL). The method was applied to the determination of 5-hydroxyindol-3-ylacetic acid in human urine, with direct sample injection.
5-Hydroxytryptophan 5-Hydroxytryptamine 5-Hydroxyindole-3-acetic acid 5-Hydroxytryptophol N-Acetyl-5-hydroxytryptamine Urine Fluorescence HPLC

"Spectrophotometric Determination Of Lead In Tap Water With 5,10,15,20-tetra(4-N-sulfoethylpyridinium)porphyrin Using Merging Zones Flow Injection"
Analyst 1993 Volume 118, Issue 7 Pages 933-936
Jeffery A. Schneider and James F. Hornig

Abstract: Determination of lead at concentrations of ≥15 µg L-1 in aqueous samples was achieved by selective reaction with 5,10,15,20-tetra(4-N-sulfoethylpyridinium)porphyrin at pH 9.4 and 30°C in a merging zones flow injection manifold followed by detection at 480 nm after an elapsed time of 45 s. Interference by aluminum (125-fold excess), cadmium (25-fold excess), copper (25-fold excess), manganese (200-fold excess) and zinc (200-fold excess) was eliminated by the use of 1.0 mol I-1 NH3-NH4CI as a buffer/masking agent; interference by iron (10-fold excess) was eliminated by the addition of 1% v/v of acetylacetone to the reagent mixture and use of the method of standard additions for sample analysis. Recoveries from tap water samples, to which various amounts of lead had been added, ranged from 98 to 109% with a detection limit of 10 µg L-1 when iron was present in the sample matrix and 4.2 µg L-1 when it was not. Results of analyzes of tap water samples using this method were in good agreement with those obtained by electrothermal atomic absorption spectrometry. Water (150 µL) was injected into a carrier stream of water simultaneously with 75 µL of 8 µM-5,10,15,20-tetra(4-N-sulfoethylpyridinium)porphyrin in 1 M NH3/NH4Cl buffer solution of pH 9.4 containing 1% acetylacetone. The injected zones merged at a mixing tee and passed through a knitted coil reactor (3 m x 0.8 mm) before the absorbance was measured at 480 nm. The system flow rates were kept at 2 ml/min to provide a mean residence time of 45 s for all analytes and the procedure was carried out at 30°C. The carrier stream was propelled through the system by gas displacement; a diagram of the manifold is given. Recoveries of Pb were 98-109%. The detection limit was 10 µg/l of Pb when Fe was present in the sample matrix and 4.2 µg/l when it was not.
Lead Water Spectrophotometry

"Simultaneous Determination Of Ammonia Nitrogen And L-glutamine In Bioreactor Media Using Flow Injection"
Analyst 1993 Volume 118, Issue 11 Pages 1361-1365
Bernhard O. Palsson, Bing Q. Shen, Mark E. Meyerhoff and Marek Trojanowicz

Abstract: Cell culture medium from reactors with growing retroviral producer cells was injected into a carrier stream of water (1 ml/min). The stream was split in half. One stream was treated with 10 µM-NH4Cl (1 ml/min) followed by 0.1 M NaOH containing 0.01 M EDTA (1.5 ml/min) at 20°C and NH3-N was determined using an NH3 gas-sensing electrode fitted with a wall-jet cap. The other stream was mixed with 0.5 M acetate buffer of pH 4.9 (1.5 ml/min) before passing through a Nafion ion-exchange coil (2 m) at 40°C, followed by a glass bead reactor containing immobilized glutaminase. The ammonium ions liberated by hydrolysis were detected potentiometrically by an ISE using absolute peak potentials. The maximum sampling rates were 40 and 35 samples/h for NH3-N and L-glutamine, respectively. In simultaneous determination of the analytes, NH3-N levels of up to 10 mmol/l could be tolerated without affecting L-glutamine measurement. The system was calibrated with Iscove's Modified Dulbecco's Medium. Results agreed with those obtained using commercial, manual enzymatic-spectrophotometric kits. A novel split stream flow injection (FI) system suitable for the simultaneous determination of L-glutamine and ammonia nitrogen (ammonia- N) in cell culture media is described. Potentiometric detection of ammonia-N in one portion of the manifold is achieved using a commercial ammonia gas-sensing electrode fitted with a wall-jet cap. L-Glutamine is quantified in the other part of the split sample by potentiometric detection of ammonium ions (by an ammonium-selective polymer membrane electrode), liberated from the hydrolysis of glutamine after the sample flows through a glass bead reactor containing immobilized glutaminase. Endogenous ammonia-N and potassium ions that would normally interfere with the glutamine measurement are removed upstream using a unique tubular cation-exchange unit. Using 50 µL sample volumes and mixed solutions of ammonium chloride and L-glutamine in Iscove's Modified Dulbecco's Medium to calibrate the FI measuring system, values for ammonia-N and L-glutamine determined for 22 media samples obtained from a bioreactor growing retroviral producer cells correlate well with those measured with commercial, manual enzymatic-spectrophotometric assay kits.
Ammonia, nitrogen l-Glutamine Fermentation broth Potentiometry Electrode Sensor

"Determination Of Formaldehyde In Reagents And Beverages Using Flow Injection"
Analyst 1994 Volume 119, Issue 6 Pages 1413-1416
Hironori Tsuchiya, Shigeru Ohtani, Kuniaki Yamada, Mioko Akagiri, Nobuhiko Takagi and Masaru Sato

Abstract: Organic solvents and water were analyzed immediately after distillation or after opening new bottles, and also after standing for 1 month. Alcoholic beverages were analyzed directly. Fruit juice was centrifuged, the supernatant solution filtered and the filtrate analyzed. Cigarette smoke was collected in phosphate buffer and the solution analyzed. A 50-100 µL portion of the sample solution was injected into a carrier stream (0.8 ml/min) of acetonitrile/0.1 M phosphate buffer of pH 2 (1:4) and the solution was passed through a column (10 cm x 4.6 mm i.d.) of NS-Gel C18 (5 µm) before being mixed with a second stream (0.5 ml/min) of a 60 mM 4-amino-3-penten-2-one solution in acetonitrile. The mixture was transported to a mixing coil kept at 60°C and the fluorescence intensity was measured at 510 nm (excitation at 410 nm). A diagram of the manifold used is given. The calibration graph was linear from 0.5-100 nmol/ml of formaldehyde. The RSD (n = 6) was 0.26%. Recoveries were quantitative. The throughput was 12 samples/h.
Formaldehyde Beverage Water Organic compound Fruit Smoke Fluorescence

"Continuous-flow System For The Accurate Determination Of Low Concentrations Of Ammonium Ions Using A Gas-permeable Poly(tetrafluoroethylene) Tube Decontaminator And An Ammonia Gas-sensing Membrane Electrode"
Analyst 1994 Volume 119, Issue 8 Pages 1839-1842
Hirokazu Hara and Susumu Matsumoto

Abstract: A calibration procedure, based on a constant-dilution method, is described for the determination of low concentrations of ammonium ions. A stream of ultrapure water (2 ml/min) was merged with a reagent stream of 0.21 M NaOH (0.1 ml/min) and the residual NH3 thus formed was removed by passing the solution through a microporous gas-permeable PTFE tube immersed in 0.5 M H2SO4 and thermostatted at 30°C. A limited volume (0.02, 0.04, 0.1, 0.2 and 1 ml/min) of standard NH4Cl solution was then added to the purified water. The diluted standard solution (2 ml/min) passed to a mixing chamber and then to an NH3 gas-sensing membrane electrode for analysis. The concentration of ammonium ions was calculated and a calibration graph was constructed. A diagram of the continuous-flow system used is given. The measurable concentration range was 0.1-5 µM of ammonium ions; the RSD (n = 5) was 0.8-1.1%. The system was used to determine low concentrations of ammonium ions in lake water.
Ammonium Lake Electrode Electrode

"Flow Injection Spectrophotometric Determination Of Aspartame In Dietary Products"
Analyst 1994 Volume 119, Issue 9 Pages 2101-2104
Joaquim de Ara&uacute;jo N&oacute;brega, Orlando Fatibello-Filho and Iolanda da Cruz Vieira

Abstract: A flow injection spectrophotometric method has been developed for the determination of aspartame in dietary products using ninhydrin as a colorimetric reagent. The reaction was conducted in a 1 + 1 v/v methanol-isopropanol medium also containing potassium hydroxide. The absorbance measurements were made at 603 nm. The results obtained for the determination of aspartame in table sweetener, pudding, gelatin, and refreshment (i.e., a powder dissolved in water for drinking) are in good agreement with the results obtained using a conventional manual procedure (correlation coefficient, r = 0.9984). Thirty-six results were obtained per hour, and the relative standard deviation was less than 3.5% (n = 6) for all samples. The detection limit (three times the signal blank/slope) was 3.8 x 10^-5 mol L-1 of aspartame. Sample (0.2-0.6 g) was stirred with 10 mL of methanol/propan-2-ol (1:1; solvent A) for 2 min. The suspension was filtered and the filtrate was diluted to 25 mL with solvent A. A portion of the solution was injected into a carrier stream (2.5 ml/min) of solvent A and subsequently merged with streams (both 0.3 ml/min) of 0.293 M KOH and 0.037 M ninhydrin (both in solvent A). The mixture was transported to a helical reaction coil (2 m x 0.8 mm i.d.) immersed in a water-bath kept at 60°C. The solution then passed through a de-bubbler after which the absorbance was measured at 603 nm. A diagram of the manifold used is given. The calibration graph was linear from 0.34-2.4 mM aspartame, the detection limit was 38 µM and the RSD (n = 6) was 3.5%. Recoveries were quantitative and the throughput was 36 samples/h. The method was applied to several dietary products, viz., table sweetener, pudding, gelatin and refreshment powder.
Aspartame Food Artificial Pudding Organic compound Soft drink Powder Spectrophotometry

"Application Of Flow Injection Spectrophotometry To The Determination Of Dissolved Iron In Seawater"
Analyst 1995 Volume 120, Issue 1 Pages 201-206
Irina Ya. Kolotyrkina, Lilija K. Shpigun, Yury A. Zolotov and Alexander Malahoff

Abstract: Two flow injection methods are described. In the first method, streams of acidified seawater and 1 M ammonium acetate were mixed and the resulting solution was pumped through a microcolumn (1 cm x 2.5 mm i.d.) packed with diethylenetriamine sorbent for 3-10 min. After washing the column with water, elution was effected by pumping a carrier stream of 0.5 M HCl through the column for 80 s. The column eluate was mixed with a reagent stream of 1 mM p-phenetidine and 9.4 mM o-phenanthroline and subsequently with a second reagent stream of 1 M ammonium acetate and 9 mM NaIO4. The mixture was passed through a reaction coil maintained at 40°C and the absorbance was measured at 540 nm. The detection limit was 0.05 µg/l of Fe. The RSD (n = 4) was 2.4-8.1%. Recoveries were 103-110%. In the second method, 300 µL 0.01 M N,N-dimethyl-p-phenylenediamine were injected into a carrier stream of Fe-depleted acidified seawater and mixed with the acidified seawater sample stream. The resulting solution was mixed with a reagent stream of 0.12% H2O2 in 2 M ammonium acetate buffer and the absorbance was measured at 554 nm. The detection limit was 0.03 µg/l of Fe. The RSD (n = 4) was 1.8-6%. Recoveries were 98-105%.
Iron Sea Spectrophotometry

"Simultaneous Spectrofluorimetric Determination Of Glycerol And Ethanol In Wine By Flow Injection Using Immobilized Enzymes"
Analyst 1995 Volume 120, Issue 1 Pages 179-182
I. L. Mattos, J. M. Fernandez-Romero, M. D. Luque De Castro and M. Valc&aacute;rcel

Abstract: Wine was diluted 2500-fold in 100 mM KHCO3/Na2CO3 buffer of pH 10 (buffer A). Two volumes of the sample solution (150 and 50 µL for glycerol and ethanol determination, respectively) were injected via a dual injection valve into two symmetrical channels containing a reagent stream (0.6 and 1 ml/min) for glycerol and ethanol determination, respectively) of 4.5 mM β-NAD in buffer A. Each plug passed through a 1.5 cm long enzyme reactor (glycerol dehydrogenase or alcohol dehydrogenase immobilized on controlled-pore glass) maintained at 35°C. A coiled reactor (300 cm long) was inserted in the ethanol channel to produce a delay between the two streams subsequently merged and passed through a 50 cm long mixing coil before fluorimetric detection at 460 nm (excitation at 340 nm). A diagram of the manifold used is given. Calibration graphs were linear from 1-10 and from 10^-100 µg/ml of glycerol and ethanol, respectively. The RSD (n = 11) were 1%. Recoveries were 97-105%. The throughput was 60 samples/h.
Ethanol Glycerol Wine Fluorescence

"Simultaneous Determination Of Several Amino Acids With Multivariate Calibration Methods By Using A Continuous-flow System"
Analyst 1995 Volume 120, Issue 2 Pages 305-312
J. Saurina and S. Hern&aacute;ndez-Cassou

Abstract: A method for the resolution of mixtures of four amino-acids, viz., phenylalanine, lysine, tryptophan and proline, is described. A stream (0.4 ml/min) of 1 mM sodium 1,2-naphthoquinone-4-sulfonate in 0.1 M HCl was mixed with a stream (0.3 ml/min) of 0.1 M Na2CO3/0.75 M NaOH buffer of pH 10. The resulting solution was merged with the sample solution (0.4 ml/min) and the mixture was passed through a PTFE reaction coil (10 m x 0.35 mm i.d.) maintained at 70°C. Absorption spectra were recorded from 290-590 nm in steps of 1 nm. Two multivariate calibration procedures, viz., principal-component regression and partial-least-squares regression, were applied to the spectra (details given). Partial-least-squares regression provided the most accurate predictions of the amino-acid composition. The method was used to determine several amino-acids in extracts of commercial feeds. The results agreed with those obtained with the standard amino-acid autoanalyzer. procedure.
Amino Acids Lysine Phenylalanine l-Proline Tryptophan Feed Spectrophotometry Sample preparation

"Use Of Focused Microwaves For Expeditive Shortening Of Sample Pre-treatment: Digestion And Reduction Procedures Prior To Selenium Speciation As Selenium(IV) Or Selenium(VI)"
Analyst 1995 Volume 120, Issue 8 Pages 2171-2174
W. Bryce, A. Izquierdo and M. D. Luque de Castro

Abstract: Methods for sample digestion and reduction of Se(VI) to Se(IV) using a focused microwave digestor, prior to Se determination, are described. The sample digestion method consisted of a three-step microwave digestion programme, using HNO3 and H2O2 (details given). The reduction of Se(VI) to Se(IV) was carried out online in a flow injection manifold in a 1 m Teflon reactor placed in the microwave chamber, using 6 M HCl as reductant. After reduction, the sample stream was diluted online before Se(IV) determination by flow injection cathodic stripping voltammetry (details given). The methods were applied to various sample types, viz., milk, sausage, kidney and water, and reduced the time required for both sample digestion and Se(VI) reduction.
Selenium(VI) Selenium(IV) Kidney Meat Food Milk Water Sample preparation Voltammetry

"Automated Determination Of Microbial Peroxidase Activity In Fermentation Samples Using Hydrogen Peroxide As The Substrate And 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) As The Electron Donor In A Flow Injection System"
Analyst 1995 Volume 120, Issue 8 Pages 2101-2105
Kaj Andr&eacute; Holm

Abstract: The sample was diluted with 0.1 M phosphate buffer of pH 7 containing 0.1 M ammonium sulfate and 1.5 g/l of Triton X-405. A portion (40 µL) of the solution was injected into a carrier stream (1.2 mL/min) of 0.2 M phosphate buffer of pH 7 containing 0.1 M (NH4)2SO4 and 1.5 g/l of Triton X-405. Reagent streams (both 0.8 mL/min) of 7.1 mM H2O2 and 1.6 mM 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) were mixed in a 30 cm coil before merging with the carrier stream. The mixture was passed through a 30 cm coil before being incubated at 40°C in a 200 cm coil. The solution was then passed through a 60 cm coil and the absorbance was measured at 418 nm. A diagram of the manifold used is given. Detection and determination limits were 0.005 and 0.05 iu/ml of peroxidase, respectively. Inter- and intra-day RSD (n = 63 and 14, respectively) were 1.1 and 4.8%, respectively. The throughput was ~e;100 samples/h. An automated flow injection method has been developed for the determination of microbial peroxidase activity. The substrate used was hydrogen peroxide and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate (ABTS) was used as the electron donor. In the presence of hydrogen peroxide, peroxidase catalyses the dehydrogenation of ABTS, resulting in the formation of a resonance-stabilized radical cation of ABTS. The green-blue color formed, recorded at 418 nm, is taken as a measure of the peroxidase activity. The general technical conditions and the general enzymatic kinetics have been optimized. Conditions for activation and stabilization of the enzyme were found, e.g., ammonium sulfate acts as a peroxidase activator. The resulting method has a good precision, sensitivity and speed.
Enzyme, peroxidase Fermentation broth Spectrophotometry

"Micellar-catalysed Reactions For Flow Injection Systems. Determination Of Pyridoxal-5-phosphate"
Analyst 1995 Volume 120, Issue 9 Pages 2401-2405
A. Alonso, M. J. Almendral, F. Merino and S. P&eacute;rez Palmero

Abstract: A flow injection method for pyridoxal 5-phosphate (I) determination is described. A portion (233 µL) of a solution of I in 0.6 M phosphate buffer of pH 7.4 (buffer A) was injected into a carrier stream (1.5 ml/min) of buffer A. The sample/carrier stream was merged with a reagent stream (1.5 ml/min) containing 1.6 mg/ml of NaCN and 0.05 M cetyltrimethylammonium bromide, and the mixture was then passed through a coiled reactor (length 50 cm). The flow was stopped for 1-6 min when the sample bolus was inside the reactor. The flow was then re-started and the fluorescence intensity of the sample zone was measured at 427 nm (excitation at 325 nm). The temperature was kept at 28°C throughout the procedure. The calibration graph was linear from 10^-100 nM of I. The detection limits were 3.1, 2.2 and 1.9 nM for stop times of 1, 3 and 6 min, respectively; throughputs were 35, 15 and 8 samples/h, respectively. The RSD (n = 10) was 1.6%. Two variations of the described procedure, viz., use of continuous-flow and cell-stop modes, are also presented.
Fluorescence

"Shipboard Determination Of Dissolved Cobalt In Seawater Using Flow Injection With Catalytic Spectrophotometric Detection"
Analyst 1996 Volume 121, Issue 8 Pages 1037-1041
Alexander Malahoff, Irina Ya. Kolotyrkina and Lilly K. Shpigun

Abstract: Seawater was filtered and acidified to pH 2. A portion (200 µL) was injected into a carrier stream of acidified seawater depleted of Co at a flow rate of 1.5 ml/min and mixed with a reagent stream of 0.01 M N,N'-diethyl-p-phenylenediamine/0. 01 M Tiron at a flow rate of 0.8 ml/min. The combined reagent/sample stream was merged with a stream of 0.2% H2O2/0.04 M NaOH/0.02 M sodium tetraborate at a flow rate of 0.6 ml/min. The mixture was passed through a 2.2 m reaction coil maintained at 30°C; absorbance was measured at 554 nm. A diagram of the manifold used is given. The calibration graph was linear from 0-300 ng/l Co; the detection limit was 1 ng/1. RSD was 1.6-10.6% (n = 5). Recoveries were 101-113% Co. The throughput was 50 samples/h.
Cobalt Environmental Sea Spectrophotometry

"Catalytic Determination Of Dissolved Inorganic Carbon In Natural Waters By Flow Injection Spectrophotometry"
Analyst 1996 Volume 121, Issue 11 Pages 1617-1619
Nelson Maniasso, Sandra Sato, Maria F. Gin&eacute; and Antonio O. Jacintho

Abstract: Sample was aspirated (2 ml/min) so as to fill a 750 µL sampling loop. The loop contents were injected into a carrier stream (1.6 ml/min) of 30 mg/l silicate of a flow injection manifold (schematic shown). The sample zone was merged successively, with reagent streams of 0.5 M acetate buffer of pH 5 (0.4 ml/min), Cr(III) (3 g/l aged for 10 days before use; 0.4 ml/min) and 0.3 M EDTA (0.4 ml/min). The mixture was passed through a 200 cm coil maintained at 45°C and the absorbance was measured at 540 nm. The calibration graph was linear for 10^-300 mg/l dissolved inorganic carbon (as hydrogencarbonate). The RSD (n = 9) at the 50 mg/l level was The throughput was 36 samples/h. The method was applied to lake, river, well and tap water. The results obtained agreed with those obtained by titrimetry.
Carbon, inorganic Environmental Water Lake River Well Spectrophotometry

"Determination Of Cadmium In Environmental Samples By Hydride Generation With In Situ Concentration And Atomic Absorption Detection"
Analyst 1997 Volume 122, Issue 4 Pages 331-336
Henryk Matusiewicz, Mariusz Kopras and Ralph E. Sturgeon

Abstract: A continuous-flow AAS system for Cd determination is described. A Cd solution acidified with HCl was mixed with 1 µg/ml Co and 0.5% thiourea (and also with 0.01 M didodecyldimethyl-ammonium bromide for reaction with KBH4) and diluted to 1 mL with water. The resulting solution was aspirated at a flow rate of 1 ml/min into a continuous-flow system and merged with a stream of either 2% NaBH4 or 4% KBH4 at a flow rate of 1 ml/min. The mixture was passed through a reaction cell/gas-liquid separator maintained at 50°C and the volatile Cd species evolved were carried by an Ar stream on to the inner wall of a GF for in situ pre-concentration at 200°C. Cd analysis was by ET AAS with atomization at 1800°C for 3 s; detection was at at 228.8 nm. The detection limit was 10 ng/l Cd with KBH4 as reagent. RSD were 10^-14% (n = 10). The method was applied to several environmental and biological CRM. The results obtained agreed with the certified values.
Cadmium Environmental NIES 1 Estuarine Sea NRCC CASS-3 NRCC PACS-1 NRCC TORT-2 Hepatopancreas NIST 2710 Plant Spectrophotometry

"Integrated Automatic Determination Of Nitrate, Ammonium And Organic Carbon In Soil Samples"
Analyst 1997 Volume 122, Issue 4 Pages 309-313
Evaristo Ballesteros, Angel R&iacute;os and Miguel Valc&aacute;rcel

Abstract: For nitrate and ammonium determination, soil was extracted with 2 M KCl. For organic C determination, soil was treated with K2Cr2O7/H2SO4 followed by dilution with water. All sample solutions were aspirated into a flow system through a filtration probe containing a hydrophobic PTFE membrane. For nitrate determination, the sample solution was passed through a Cu-coated Cd column before reaction with N-(1- naphthyl)-ethylenediamine and sulfanilamide; absorbance was measured at 540 nm. For ammonium determination, the sample solution was mixed with EDTA before reaction with phenol/nitroprusside in the presence of hypochlorite buffer of pH 11.4-12.3 at 50°C; absorbance was measured at 636 nm. Organic C was determined by mixing the sample solution with 15% H2SO4 and measuring the absorbance at 600 nm. The calibration graphs were linear from 0.25-4 and 0.4-8 µg/ml nitrate and ammonium, respectively, and from 0.1-2% for organic carbon. The detection limits were 0.1 µg/ml for both nitrate and ammonium, and 0.05% for organic C. RSD were 2-2.6% (n = 11). Recoveries were 87-102%. The throughput was 15-60 samples/h. An automated photometric method for the sequential determination of nitrate, ammonium and organic carbon in soils by use of a single-line flow injection assembly is reported, but differently programmed for the assay of the individual analytes, These analytes, which are determined by using suitable photometric reagents, are directly related to the nutritional properties of soil, A filtration probe was used for the continuous filtration of soil extract, The precision, expressed as RSD, was 2.0, 2.6 and 2.1% for nitrate, ammonium and organic carbon, respectively. The proposed method features a high throughput and low reagent consumption, and requires minimal sample handling, Its performance was tested in routine analyzes of soil samples, all with satisfactory results. (26 References)
Ammonium, nitrogen Carbon, organic Nitrate Environmental Spectrophotometry Sample preparation

"Determination Of Amyloglucosidase Activity Using Flow Injection Analysis With Fourier Transform Infrared Spectrometric Detection"
Analyst 1997 Volume 122, Issue 6 Pages 531-534
R. Schindler, B. Lendl and R. Kellner

Abstract: Samples (250 µL each) and a 55 g/l starch solution in 0.1 M acetate buffer of pH 4.3 were simultaneously injected into two aqueous carrier streams (both at a flow rate of 0.88 ml/min) and merged in a reaction coil (250 cm x 0.5 mm i.d.) maintained at 54°C. When the reaction plug had filled the reaction coil, the flow was stopped for 5 min after which the FTIR spectrum was recorded from 950-1300 cm-1. The amyloglucosidase (I) activity was calculated from the difference in the absorbances at 1078 and 1020 cm-1 compared with a reference spectrum of unreacted starch. The calibration graph was linear from 50-2000 U/l I. The method was applied to fermentation broths: recoveries were 98-102% of added I.
Amyloglucosidase Fermentation broth Spectrophotometry

"Determination Of Trimethylamine In Fish By Pervaporation And Photometric Detection"
Analyst 1997 Volume 122, Issue 7 Pages 663-666
J. A. Garc&iacute;a-Garrido and M. D. Luque de Castro

Abstract: Two methods for trimethylamine determination in fish are described. In the first method (method A), the sample was extracted with TCA. The filtered extract was mixed with streams of formaldehyde and NaOH in a continuous-flow manifold before reaching a pervaporation cell kept at 60°C. The analyte evaporated and diffused through a PTFE membrane into a Bromothymol Blue solution of pH 6 and the color change was recorded. In the second method (method B), the sample was mixed with TCA, formaldehyde and NaOH directly in the pervaporation cell. After 5 min at 60°C, the analyte was collected in a Bromothymol Blue solution of pH 6 and the color change was recorded. The calibration graphs were linear for 2-30 mg/l and for 0.1-10 mg/g trimethylamine for methods A and B, respectively; the corresponding detection limits were 1.6 mg/l and 0.08 mg/g. The RSD (n = 11) were 3.5-4.3%. The throughputs were 8 and 2 samples/h for methods A and B, respectively.
Trimethylamine Marine Spectrophotometry

"Determination Of Dissolved Reactive Phosphorus In Estuarine Waters Using A Reversed Flow Injection Manifold"
Analyst 1997 Volume 122, Issue 12 Pages 1477-1480
Stefan Auflitsch, Darren M. W. Peat, Ian D. McKelvie and Paul J. Worsfold

Abstract: The Schlieren or refractive index (RI) effect is a major problem in the determination of dissolved reactive phosphorus in estuarine waters using conventional flow injection (FI) manifolds with sample injection, This is because differences in RI between the injected sample zone and the carrier stream give rise to a lensing effect which is superimposed on the blank response and causes significant error in quantitation, A simple reversed flow injection (rFI) manifold using spectrophotometric detection which removes these quantitation errors is reported. Acidic molybdate is injected into a sulfuric acid carrier stream of the same refractive index and sequentially merged with sample and reductant (ascorbic acid), Reduction of phosphomolybdate to phosphomolybdenum blue is carried out in a coil thermostated at 60°C. Dissolved reactive phosphorus has been successfully determined in estuarine waters with salinities ranging from 0 to 30 parts per thousand using calibration standards prepared in deionized water, with a detection limit of 2 µg L-1 PO4-P and a linear range of 2-100 µg L-1 PO4-P (r2 = 0.9998).
Phosphorus Estuarine Spectrophotometry

"Determination Of Carbonyl Compounds By The Oxidative Chemiluminescence Of 2,4-dinitrophenylhydrazine"
Analyst 1998 Volume 123, Issue 5 Pages 1047-1051
Alan Townshend and R. Alan Wheatley

Abstract: The oxidative chemiluminescence of phenylhydrazines can be applied to the determination of carbonyl compounds by utilizing the attenuation of the signal which occurs on conversion to the corresponding phenylhydrazone. Using an assay for 2,4-dinitrophenylhydrazine, off-line derivatization for a period of 2 h is optimized for a temperature of 30°C and for a sulfuric acid concentration. of 0.05 M. The optimum conditions for 2,4-dinitrophenylhydrazone formation can be understood in terms of a stepwise mechanism of carbinolamine formation via a zwitterion intermediate. The log-log calibration for the combined derivatization/assay of hexanal in optimized conditions is linear (r = 0.9931, n = 5) from 1 x 10^-6 to 2 x 10^-5 M. The limit of detection calculated as above was 1.7 x 10^-7 M (1.7 pmol of hexanal). Applications to the oxidative deterioration of linoleic acid and to the effect of lipoxygenase on linoleic acid are described.
Carbonyl compounds Linoleic acid Chemiluminescence

"Flow Injection Spectrophotometric Determination Of Acetylsalicylic Acid In Tablets After Online Microwave-assisted Alkaline Hydrolysis"
Analyst 1998 Volume 123, Issue 5 Pages 1011-1015
Airton Vicente Pereira, Clezio Aniceto and Orlando Fatibello-Filho

Abstract: The proposed method is based on an online microwave-assisted alkaline hydrolysis of acetylsalicylic acid (ASA) to salicylic acid (SA) that reacts with Fe3+ to form a complex that absorbs light at 525 nm. Samples merged with NaOH were passed continuously through a domestic microwave oven in order to accelerate the hydrolysis of ASA. Under the best anal. conditions, the linearity of the calibration equation ranged from 25 to 250 µg ASA/mL. The precision for 10 successive measurements of 200 µg ASA/mL presented a relative standard deviation of 0.40%. The detection limit was 4.0 µg/mL and recoveries of 99.1-101.0% were obtained for ASA. No interference was observed from the common tablet excipients and other active substances such as ascorbic acid and caffeine. The proposed flow injection method is fast and permits the determination of ASA in 90 samples per h.
Acetylsalicylic acid Pharmaceutical Spectrophotometry

"Determination Of Selenium Species In Seawater By Flow Injection Hydride Generation In Situ Trapping Followed By Electrothermal Atomic Absorption Spectrometry"
Analyst 1998 Volume 123, Issue 7 Pages 1565-1569
Jean Yves Cabon and Wolfgang Erler

Abstract: In this study, Se(IV) was determined in seawater by flow injection hydride generation, trapping within the graphite furnace, followed by electrothermal atomic absorption spectrometry. The optimized protocol permitted a pre-concentration factor of 1000 lowering the detection limit of Se(IV) in seawater to about 1.5 ng L-1 for a 25 mL sample volume Because this technique is specific to Se(IV), various physico-chemical treatments leading to the conversion of other chemical forms into Se(IV) were investigated. Thermal and UV irradiation treatments of seawater samples in acidic or basic medium permitted the conversion of Se(II)-selenomethionine and Se(VI) to Se(IV). Based on the different responses of selenium species towards the photochemical treatments, an operational speciation model of selenium species in seawater is proposed. According to our anal. protocol, 21 ng L-1 Se(VI), 10 ng L-1 Se(IV) and 13 ng L-1 organic Se(II) species were determined in a coastal surface seawater collected near Brest. (34 References)
Selenium(IV) Selenomethionine Sea Spectrophotometry

"Highly Sensitive Flow Detection Of Uric Acid Based On An Intermediate Regeneration Of Uricase"
Analyst 1998 Volume 123, Issue 8 Pages 1775-1780
Yasushi Hasebe, Kimihisa Nawa, Shinya Ujita and Shunichi Uchiyama

Abstract: The principle of the signal amplification of a uric acid sensor based on dithiothreitol (DTT)-mediated intermediate regeneration of uricase was applied to a flow injection system with an immobilized uricase reactor and a DTT-containing carrier. Highly sensitive detection for nM to µM order of uric acid was achieved when 10 mM TRIS-HCl buffer (pH 10.0) containing 20 mM DTT was used as a carrier at 0.6 mL min-1 and 37°C. The sensitivity of the uric acid was much improved over a batch method using a uricase membrane-coupling electrode, and the detection limit (ca. peak current 8 nA) of uric acid was found to be down to 3 x 10^-10 M (amplification factor; more than 10000). This chemical amplified flow-system is very useful for the direct assay of uric acid in highly diluted biological fluids (urine and serum) without complicated pretreatment of the samples, because this sensor has the potential to detect trace amounts (nM to µM) of uric acid in highly diluted body fluids in which the concentration. of interfering constituents was decreased to negligible levels. Good correlation was observed between this system and conventional spectrophotometry. The immobilized uricase reactor could be re-used for at least 4 months of repeated analysis without loss of activity and was stable if stored at 4°C in 10 mM TRIS-HCl buffer, pH 9.0.
Uric acid Blood Serum Urine Electrode Electrode

"Determination Of Selenium In Solid Samples By Continuous Subcritical Water Extraction, Flow Injection Derivatization And Atomic Fluorescence Detection"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 8 Pages 787-791
C. M. Rico Varad&eacute; and M. D. Luque de Castro

Abstract: A method for the determination of selenium in solid samples is proposed. The method involves two main steps: (a) continuous leaching of the analyte by subcritical water (250°C, 200 bar, 0.7 mL min-1), which is complete in 15 min and (b) continuous derivatization (hydride formation) and detection by atomic fluorescence. The design of the derivatization manifold, based on flow injection, enables speciation anal. of inorganic selenium (as Se(IV)/Se(VI)) and organo-selenium compounds by appropriate selection of the reagent streams. Both conversions of organic into inorganic Se by oxidation and reduction of the Se(VI) formed as well as that of Se(VI) initially present in the samples to Se(IV) is accelerated by irradiation with focused microwaves using 1 m reactors and a flow-rate of 4.4 mL min-1. The linear range of the calibration curves is between 10^-50,000 ng mL-1 with relative standard deviation values <4.5%. The method was applied successfully to sludge samples from an interlaboratory study. The drastic conditions of extraction convert organic Se into inorganic, so the method does not enable inorganic-Se/organic-Se speciation in solid samples.
Selenium Waste Fluorescence Sample preparation

"Kinetics In A Single Bead String Reactor For Flow Injection Analysis"
Anal. Chem. 1984 Volume 56, Issue 6 Pages 943-948
J. M. Reijn, H. Poppe, and W. E. Van der Linden

Abstract: A theoretical study is presented, and the results are shown to correspond with those obtained experimentally by monitoring the dispersion of the injected-sample zone with use of reacting and non-reacting systems. In the reacting system, the formation of Cr(III) - EDTA complexes by injection of 1 mM Cr(III) into a stream of 0.01 M EDTA at 60°C and pH 4.2 was observed, and in the non-reacting system 1 mM KMnO4 in 0.1 M KNO3 was injected into a stream of 0.1 M KNO3.
Chromium(III) Spectrophotometry

"Determination Of N-methylcarbamate Pesticides In Well Water By Liquid Chromatography With Post-column Fluorescence Derivatization"
Anal. Chem. 1984 Volume 56, Issue 13 Pages 2465-2468
Kenneth M. Hill, Richard H. Hollowell, and Leo A. Dal Cortivo

Abstract: The compounds were separated by HPLC on a column (25 cm x 4.6 mm) of Zorbax C8 at 31°C with gradient elution with methanol - water. Derivatization was achieved on a Kratos URS 051 post-column reaction system, with phthalaldehyde and 2-mercaptoethanol, and fluorimetric detection was at >418 nm (excitation at 230 nm). Recoveries were generally >95% at pH <6.0 at the 8- and 40-ppb levels. In the analysis for aldicarb, good correlation between results by the method proposed and those of a g.c. method was obtained (r = 0.991). The HPLC method also allowed analysis for other pesticides, such as carbofuran and oxamyl.
Pesticides Aldicarb Carbofuran Oxamyl Well HPLC Fluorescence

"Flow Injection Analysis Of Phenols Via Bromination And Detection Of Unreacted Bromine At A Platinized Gas Diffusion Membrane Electrode"
Anal. Chem. 1986 Volume 58, Issue 4 Pages 983-985
Antonin Trojanek and Stanley Bruckenstein

Abstract: A portion of the test solution in 1 M H2SO4 is injected into a stream of 0.01 to 1 mM KBr - 50 mM KBrO3, and, after passage through a 60-cm reaction coil at 50°C, unreacted Br is determined amperometrically by reduction at a platinum gas permeable membrane electrode in a cell similar to that described previously (see earlier in this section). A potential of +0.30 V vs. the SCE is applied to the platinum electrode and the supporting electrolyte is 0.1 M H2SO4. The analytical range can be extended by appropriate changes in the concentration. of KBr in the carrier stream. With 0.1 mM KBr, calibration graphs are rectilinear for 10 to 200 ng of resorcinol, 20 to 300 ng of phenol and 30 to 650 ng of 2-naphthol. The reproducibility of production of Br by acidification of the composite reagent is 1.1% (n = 20). Alternatively, the Br can be introduced into the carrier stream by permeation, thus providing a possible means of post-column reaction for the detection of phenols in HPLC.
Phenols 2-Naphthol Amperometry HPLC Electrode Electrode

"Determination Of Triglycerides By High Performance Liquid Chromatography With Post-column Derivatization"
Anal. Chem. 1986 Volume 58, Issue 12 Pages 2380-2383
Yukihiro Kondoh and Satoshi Takano

Abstract: The triglycerides are separated on two columns (15 cm x 4.6 mm) of Hitachi gel 3057 at 35°C with ethanol - acetonitrile (either isocratic or gradient elution) as mobile phase (0.8 mL min-1). The eluate is passed to a post-column reactor, where the triglycerides are hydrolyzed with 2.4% KOH in aqueous 60% ethanol and the resulting glycerol is oxidized at 70°C with 10 mM H5IO6 in ammonium acetate - acetic acid buffer (pH 5.5) to formaldehyde which is reacted with 0.2 M acetylacetone in the presence of ammonium acetate. The product is detected at 410 nm. Calibration graphs for trilaurin, trimyristin, tripalmitin and tristearin are rectilinear from 0.3 to 59.9, 0.3 to 50.7, 0.5 to 25.7 and 1.1 to 11.2 nmol, respectively, with coefficient of variation (n = 5) at the 5 µg level of <3.3%. The method has been applied to coconut oil.
Triglycerides Trilaurin Trimyristin Tripalmitin Tristearin Oil HPLC Spectrophotometry

"Electrochemical Determination Of Sulfur Dioxide In Air Samples In A Closed-loop Flow Injection System"
Anal. Chem. 1987 Volume 59, Issue 4 Pages 666-670
Angel Rios, M. D. Luque de Castro, Miguel Valcarcel, and Horacio A. Mottola

Abstract: The method involved injection of the gaseous sample (198 µL) into a carrier solution (pH ~4.5) containing ~1 mM di µ-hydroxybis[bis-(1,10-phenanthroline)]iron(III)(I) (flow rate 1.2 mL min-1, total volume 100 ml). After reaction at the gas - liquid interface at 50°C in the mixing coil (length 125 cm), the extent of reduction to ferroin(II) was amperometrically monitored at 0.964 V vs. silver - AgCl, with a carbon-paste working electrode and a vitreous-carbon auxiliary electrode. Regeneration of I was accomplished in the closed loop system by electrochemical oxidation of II. By application of a continuous-flow/stopped-flow operation (stop time 30 s), SO2 was determined at the 5.0 ppm level with a coefficient of variation (n = 11) of 3.2%; 25 samples could be analyzed in 1 h. By pretreatment of the carbon-paste electrode with Triton X-100, a similar detection limit was achieved with continuous-flow operation, at a rate of 35 samples h-1.
Sulfur dioxide Environmental Amperometry Electrode

"Stopped-flow Determination Of The Parameters Affecting The Application Of Peroxyoxylate Chemiluminescence To High Performance Liquid Chromatographic Detection"
Anal. Chem. 1988 Volume 60, Issue 20 Pages 2193-2197
Nobuaki Hanaoka, Richard S. Givens, Richard L. Schowen, and Theodore Kuwana

Abstract: The mechanism of the cited chemiluminescence and the optimization of parameters for its creation were studied with special reference to the parameters of temperature and imidazole buffer concentration. Measurements with use of a time window concept (sampling interval 10 to 200 ms) in a stopped-flow system were preferred to those by standard flow injection analysis. Conditions used were designed to simulate those arising in a detection system for reversed-phase HPLC.
Chemiluminescence HPLC

"Thermal-gradient Micro-bore Liquid Chromatography With Dual-wavelength Absorbance Detection"
Anal. Chem. 1991 Volume 63, Issue 6 Pages 568-574
Curtiss N. Renn and Robert E. Synovec

Abstract: A single fiber-optic two-wavelength detector is described for remote sensing in thermal-gradient microbore LC (TGMLC). Theoretical relationships are derived relating changes in the refractive index of the LC mobile phase to aperture-limited absorbance measurements. The use of the detector system was illustrated by the reversed-phase separation of unleaded gasoline on a C18 column, with a temperature gradient of 25°C to 150°C over 30 min, methanol - water as the mobile phase and detection at 230 and 295 nm. The detector reduced the baseline drift associated with thermally induced refractive index aberrations, not only for TGMLC but also for mobile-phase gradient LC and flow injection analysis. The advantages of the TGMLC technique are discussed.
LC Spectrophotometry

"Development Of Catalytic Photometric Flow Injection Methods For The Determination Of Selenium"
Anal. Chem. 1991 Volume 63, Issue 7 Pages 692-699
aul M. Shiundu and Adrian P. Wade

Abstract: A carrier stream of 0.1 M phenylhydrazine hydrochloride was merged with a flow of 0.5 M KClO3 to give a total flow rate of 1.0 mL min-1. The mixture was passed via an injection valve, where the Se(IV) sample was added to, a 50-cm reaction coil. Two other channels of 1.2 M HCl (0.5 mL min-1) and 0.02 M chromotropic acid (0 to 1 mL min-1) were merged before all the streams were passed through a 300-cm reaction coil at 60°C. The absorption of the red complex was measured at 360 nm using a diode-array spectrophotometer. The reaction followed pseudo-first-order kinetics. Interference studies showed that most metal ions could be tolerated at 100 ppm and others could be masked with EDTA. The performance of the optimized conventional flow injection manifold was compared with that of stopped-flow and flow-reversal configurations. The conventional manifold had a sample throughput rate of >60 h-1, a detection limit of 0.52 ppm of Se(IV) and a rectilinear range of 0 to 50 ppm. When the sample plug was stopped for 30 s, the sensitivity was increased by a factor of 2.5 while maintaining a throughput of 45 h-1. At this rate, the flow-reversal method gave improved sensitivity and a detection limit of 0.15 ppm. A reverse trend of conventional >stopped-flow >flow reversal was observed for the rectilinear dynamic range.
Selenium Spectrophotometry

"Measurement Of Carbonyl Compounds As The 2,4-dinitrophenylhydrazonate Anion. Reaction Mechanism And An Automated Measurement System"
Anal. Chem. 1994 Volume 66, Issue 13 Pages 1965-1970
Purnendu K. Dasgupta, Genfa Zhang, Shawn Schulze, and John N. Marx

Abstract: Formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, p-(dimethylamino)benzaldehyde, glyoxal (I), acetone, benzoylacetone (II), 2,3-butanedione, 2,4-pentanedione (III), isovaleraldehyde or methylisobutylketone were dissolved in methanol and portions (18 µL) were injected into a carrier stream (~1 ml/min) of methanol. This merged with a stream of 2,4-dinitrophenylhydrazine (DNPH; 200 mg in 50 mL of methanol and 4 mL of concentrated HCl, diluted to 100 mL with H2O) and passed to a PTFE reactor coil (300 cm x 0.3 mm i.d.) at 60°C for 18 min. Reaction with 10% KOH in methanol/H2O (4:1) then took place in a second reaction coil (300 cm x 0.72 mm i.d.) at 60°C for >90 s, and the resulting quinonoid anion was detected at 470 or 480 nm. Calibration graphs were linear over two orders of magnitude for C21-C9 aliphatic carbonyl compounds and the detection limit was 0.5 mg/l; sample throughput was 20/h. I precipitated and ketones II and III failed to react sufficiently. The mechanism of the base-catalyzed decomposition of DNPH was investigated by NMR (details given). The method was applied to an alcohol ethoxylate sample.
Carbonyl compounds Formaldehyde Acetaldehyde Propionaldehyde Benzaldehyde 4-Dimethylaminobenzaldehyde Glyoxal Acetone Benzoylacetone 2,3-Butanedione Pentanedione, 2,4- Isovaleraldehyde Methyl isobutyl ketone Ethoxylate Spectrophotometry

"Determination Of Phosphate By Flow Injection Analysis Using Geometrically Deformed Open Tubes"
Fresenius J. Anal. Chem. 1984 Volume 319, Issue 3 Pages 277-281
H. Engelhardt und R. Klinkner

Abstract: The use of geometrically deformed open tubes ('knitted capillaries') for the rapid determination of PO43- in flow injection systems is described. By using the method of Eibl and Lands (Anal. Abstr., 1970, 19, 2190), a capillary tube (250 cm x 0.25 mm) at 70°C permitted the determination of PO43- with a reaction time of 4 s. The detection limit was 0.2 ppm, and the method enabled 300 determinations to be performed hourly. The use of a cyclone mixing chamber allowed thorough mixing of sample and reagent.
Phosphate Spectrophotometry

"Determination Of Nitrate In Natural Waters By Flow Injection Analysis"
Fresenius J. Anal. Chem. 1984 Volume 319, Issue 5 Pages 506-509
Susumu Nakashima, Masakazu Yagi, Michio Zenki, Akinori Takahashi and Kyoji T&ocirc;ei

Abstract: The sample is injected into a carrier solution containing 0.8 g L-1 of Na4EDTA and 3 g L-1 of NH4Cl (pH ~8.1), and the stream passes through copperized cadmium to reduce NO3- to NO2-. The reagent (containing 552 mg L-1 of m-phenylenediamine dihydrochloride and 200 mg L-1 of 4'-aminoacetophenone; pH 2) is added, the solution are mixed at 45°C, and the absorbance of the product is measured at 456 nm. The detection limit is 1.5 ppb with injection of 650 µL of water, and, at 0.1 to 0.3 ppm of nitrate-N, the coefficient of variation is <1%. Nitrite present in the sample is determined separately and corrected for. Of the foreign ions examined, 50 ppm of Ca(II), Mg(II), Na+, K+, NH4+, HCO3-, SO42-, Cl-, SiO32- or H2PO4- did not interfere in the determination of 0.2 ppm of nitrate-N. Results for NO3- in 10 natural water samples are reported.
Nitrate Environmental Spectrophotometry

"Optimization Of Ion-chromatographic Trace Analysis For Heavy And Alkaline-earth Metals By Post-chromatographic Derivatization"
Fresenius J. Anal. Chem. 1987 Volume 327, Issue 5-6 Pages 503-508
Da -ren Yan, und Georg Schwedt

Abstract: Six metal ions (Fe(III), Cu, Zn, Co, Fe(II) and Mn in elution order) can be separated in 2.5 min by HPLC on a glass column (10 cm x 3 mm) packed with the strong-acid silica gel cation exchanger BT V TM (10 µm; Biotronik) and operated with a mobile phase (2 mL min-1) of 0.25 M tartrate (pH 2.45). A mixture containing 11 ions (additionally Pb, Ni, Cd, Ca and Mg) was separated in 24 min by HPLC on a glass column (20 cm x 4 mm) packed with BT V TM and operated with a mobile phase (1.3 mL min-1) of 0.1 M tartrate (pH 3.05). Detection (at 490 nm) followed post-column derivatization (60°C, 0.25 mL min-1) with a reagent containing 1 mM 4-(2-pyridylazo)resorcinol, 2 M NH3 (pH 11) and, for the 11-elements separation, 0.25 mM ZnEDTA. Detection limits were 1 to 2 ppb although, with pre-concentration. of water samples on a column (5 cm x 3 mm) packed with BT V TM, metals in concentration. 1 part in 1012 could be determined.
Metals, alkaline earth Metals, heavy Iron(III) Copper Zinc Cobalt Iron(2+) Manganese Water HPIC Spectrophotometry

"Dual Detection For Optimization Of Gas Diffusion In Flow Injection Analysis. Determination Of Ammonium And Sulfide"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 714-717
G. Schulze Contact Information, M. Brodowski, O. Elsholz und A. Thiele

Abstract: Flow diagrams are given for the flow injection determination of sulfide (as H2S) and ammonium (as NH3), with use of a gas-permeable membrane for analyte transfer from donor to acceptor stream. The efficiency of this transfer has been studied. For H2S, a retardation loop was used to connect the donor stream to the 644-nm detector for parallel monitoring of both streams; the efficiency was 30 to 40%. For NH3, two parallel gas diffusion unit - 578-nm detector systems were used; the efficiency was ~7%. At 80°C, the efficiency increased by factors of 1.2 and 1.8, respectively, over that at ambient temperature Two PTFE materials are recommended for membrane construction.
Ammonium Sulfide Spectrophotometry

"Determination Of Hydroxyproline In Meat Products By Flow Injection Analysis"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 732-734
J. M&ouml;ller and A. Sj&ouml;din

Abstract: Samples (10 g) were wrapped in tin foil and hydrolyzed (105°C, 15 h) with 30% H2SO4 (30 ml) or 6 M HCl (30 ml), then diluted to 500 mL. After filtration, the sample (100 µL) was injected into a carrier stream (hydrolysate blank, 0.6 mL min-1) and merged with oxidation reagent, aqueous 1.4% chloramine T - buffer (citrate - acetate, in aqueous 29% propanol; pH 6.0) (1:9; 0.6 mL min-1), and with color reagent, aqueous 10% dimethylaminobenzaldehyde - 70% HClO4 - propanol (2:1:1) (0.6 mL min-1). The reaction coil was operated at 80°C to 85°C and detection was at 550 nm. Sample throughput was 30 h-1 and the coefficient of variation (n = 20) was 1% for 50 mg L-1 of hydroxyproline.
Hydroxyproline Meat Spectrophotometry

"Ion Chromatography Of Gallium, Indium And Thallium With Applications To The Analysis Of Ores"
Fresenius J. Anal. Chem. 1988 Volume 331, Issue 6 Pages 601-606
Daren Yan, Jingan Zhang und Georg Schwedt

Abstract: Gallium, In, Tl(III), Fe(III), Cu(II), Pb(II) and Zn were separated in 15 min by ion chromatography on a Nucleosil 10SA column (22 cm x 4.6 mm) with 0.1 M tartrate - 0.12% NaCl (pH adjusted to 2.25 with HCl) as mobile phase (1.1 mL min-1). After post-column derivatization with 1 mM 4-(2-pyridylazo)resorcinol - 0.5 mM ZnEDTA - 2 M NH3 at pH 11 and 60°C in a 6-m reaction coil, the metals were detected at 495 nm. Rectilinear calibration ranges varied from 0.08 to 8 ppm of Fe(III) to 0.4 to 40 ppm of Tl(III), Ga, In and Pb(II). A described procedure for the simultaneous determination of Ga and In in complex ores was applied to one synthetic and four natural samples, e.g., a silicate, containing 40 ppm to 0.1% of Ga and In. For determination of all seven metals in the synthetic sample the coefficient of variation were 2.8% (n = 7).
Copper(II) Indium Iron(III) Gallium Lead(2+) Thallium Zinc Geological HPIC Spectrophotometry

"Determination Of Arsenic(III) And Total Inorganic Arsenic By Online Pre-treatment In Hydride Generation Atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1992 Volume 343, Issue 4 Pages 352-356
Wolfgang Driehaus and Martin Jekel

Abstract: A continuous-flow hydride generation AAS system (suitable for monitoring water supplies) is described. In order to determine As(III) and As(V) with the same sensitivity the sample is continuously mixed with concentrated HCl and a KI - ascorbic acid solution in a 1.5-m reaction coil heated to 75°C. The calibration graph extends from 1 to 100 µg L-1 with a rectilinear range up to 20 µg L-1 and a detection limit of 0.6 µg l-1. The chosen reaction medium for the selective determination of As(III) was 0.5 M acetic acid which gave a working range from 1 to 50 µg L-1 with a rectilinear range up to 20 µg l-1. With this determination Cu, Fe and Ni can interfere at a concentration. of 1 mg l-1, but the interferences can be suppressed by the addition of thiourea (60 mM) and EDTA (20 mM) to the acetic acid matrix.
Arsenic(3+) Arsenic, total Environmental Sample preparation Spectrophotometry

"Determination Of Six Arsenic Species By High Performance Liquid Chromatography-hydride Generation-atomic Absorption Spectrometry With Online Thermo-oxidation"
Fresenius J. Anal. Chem. 1993 Volume 346, Issue 6-9 Pages 643-647
M. A. L&oacute;pez, M. M. G&oacute;mez, M. A. Palacios and C. C&aacute;mara Contact Information

Abstract: Anion-exchange HPLC has been coupled to online thermo-oxidation and hydride generation-atomic absorption spectrometry (HG-AAS) for the speciation of As(V), As(III), MMA, DMA, AsB and AsC. The thermoreactor consists of a loop of PTFE tubing dipped in a powdered-graphite oven heated to + 140°C. Samples and persulfate solution run together into the thermo-reactor. The thermo-oxidation conditions were optimized using a FIA system. The chromatographic and chemical parameters affecting hydride generation efficiency were optimized. The overlap of the As(III) and AsB peaks made it necessary to determine AsB as the difference between absorbance in the presence and in the absence of thermo-oxidation. The thermo-conversion efficiencies were above 96%. Recoveries were around 100% and detection limits below 1 ng. The proposed method is rapid, sensitive and precise (RSD about 5%), making it suitable for online determination in environmental samples.
Arsenic(3+) Arsenic(5+) Arsenoβine Monomethylarsine Dimethylarsenic Arsenocholine Environmental HPLC Spectrophotometry

"Individual And Simultaneous Determination Of Ephedrine And Phenylephrine By The Use Of Kinetic Methodology"
Fresenius J. Anal. Chem. 1994 Volume 349, Issue 12 Pages 824-828
B. Gala, A. G&oacute;mez-Hens and D. P&eacute;rez-Bendito

Abstract: A 0.1 mL portion of 0.2 mM NaIO4 and 0.5 mL 1 M KHCO3 were added to a solution of ephedrine (I) and phenylephrine (II) (140 µg/ml of I and or II in a final volume of 10 ml); after 5 min 0.75 mL 0.4 mM NaAsO2 was added and the mixture diluted to 10 mL (Solution A). One of the two 2 mL reservoir syringes of a stopped-flow module was filled with a solution containing 0.8 mM HCl, 1.2 mM 2-methylbenzothiazole-2-one hydrazone and a volume of A containing aldehydes corresponding to 0.7-70 µg/ml of I or II. The other was filled with a solution that contained 0.14 mM FeCl3 and 0.64 mM sulfamic acid. A 0.15 mL portion from each was transferred to a mixing chamber at 50°C. Absorbance was measured at 620 nm for 2 min and data processed by linear regression program. Reaction rates were measured from 30-90 s after the start of the reaction. Calibration graphs were linear for 0.7-70 µg/ml of I and 1.2-70 µg/ml of II, respectively. The mean recovery of I was 103.2% and synthetic mixtures containing I/II ratios between 3:1 and 1:5 were resolved.
Ephedrine Phenylephrine Spectrophotometry

"Speciation Of Mercury In Soils And Sediments By Thermal Evaporation And Cold Vapor Atomic Absorption"
Fresenius J. Anal. Chem. 1994 Volume 350, Issue 1-2 Pages 18-20
G. Bombach, K. Bombach and W. Klemm

Abstract: Evaporation studies of mercury in several chemical compounds, soils, and sediments with a high content of organic matter indicate that a quantitative release is possible at temperatures as low as 400°C. The desorption behavior from a gold column is not influenced. Only from samples with a thermal prehistory, such as brown coal ash, did mercury evaporate at higher temperatures. Qualitative conclusions can be derived about the content of metallic mercury as well as mercury associated with organic matter or sulfide. A comparison of the analytical results obtained by using the evaporation technique or by dissolving using a mixture of concentrated HCl and HNO3 shows good agreement; the advantages of the evaporation technique are obvious at very low mercury concentrations.
Mercury Environmental Environmental Sample preparation Spectrophotometry

"Sequential Speciation Of Selenium By Flow Injection Cathodic-stripping Voltammetry"
Fresenius J. Anal. Chem. 1995 Volume 351, Issue 4-5 Pages 433-437
D. W. Bryce, A. Izquierdo and M. D. Luque de Castro

Abstract: A schematic is given of the flow injection manifold used. For Se(IV), the sample loop was filled with sample and deposited onto a vitreous C electrode at 0.0 V for 3.5 min. After stopping the flow for 15 s, a cathodic scan was applied from 0.0 to -0.9 V and Se was stripped at -0.54 V; the current being proportional to the concentration of Se(IV). For Se(VI), the Se must be reduced to Se(IV) for measurement. Sample (5 ml) was mixed with 10 mL 6 M HCl in a covered beaker and heated at 70°C for 1 h. After cooling, the solution was diluted to 50 mL with water and then again with 0.1 M HCl. Se(IV) was then determined as above and Se(VI) was calculated from the difference of the resulting currents between the reduced and non-reduced samples. Calibration graphs were linear from 0.5-30 ng/ml of Se(IV) and Se(VI). Ag/AgCl was used as the reference electrode together with a Au auxiliary electrode. The effects of interfering species are discussed. The method was applied to Se speciation in natural waters.
Selenium(IV) Selenium(VI) Environmental Voltammetry Electrode

"Spectrophotometric Simultaneous Determination Of Creatinine And Creatine By Flow Injection With Reagent Injection"
Fresenius J. Anal. Chem. 1995 Volume 352, Issue 6 Pages 557-561
Gloria del Campo, Ana Irastorza and J. Alfonso Casado

Abstract: Stock cubes (meat and fish) were dissolved in water by heating at 60°C with agitation and the resulting solution was cooled and filtered. After dilution with water a 220 µL portion was injected into the carrier stream of 2 g/l picric acid in 20 g/l NaOH in a FIA system. The system passed through a reaction coil (600 cm x 0.7 mm i.d.) and merged with 0.2 g/l of biacetyl and 25 g/l of 1-naphthol in 20 g/l of NaOH. The resulting stream passed through a second reaction coil (500 cm x 0.7 mm i.d.) to a spectrophotometer where the absorbance was measured at 520 nm. All flow rates were 0.9 ml/min and all reactions took place at 40°C. Calibration graphs were linear up to 30 mg/l of creatinine and creatine. RSD (n = 3) were 0.3-1.65% for 2-20 mg/l of creatinine and 0.34-0.67% for 2-30 mg/l of creatine. Recoveries were 99.6-102.9% for creatinine and 96.5-100.4% for creatine from meat and fish stock cubes.
Creatine Creatinine Cube Cube Spectrophotometry

"Spectrophotometric Determination Of Dopamine And Methyldopa With Metaperiodate By Flow Injection Analysis"
Fresenius J. Anal. Chem. 1995 Volume 353, Issue 2 Pages 221-223
J. J. Berzas Nevado Contact Information, J. M. Lemus Gallego and P. Buitrago Laguna

Abstract: Tablets were dissolved in 0.02 M acetate buffer of pH 4.8 to give a concentration of 8 M dopamine or methyldopa with ultrasonication followed by filtration. Aqueous formulations of dopamine and methyldopa were diluted with the above buffer to give a concentration of 20-200 µM. The resulting solutions were analyzed by FIA as previously described (Anal. Chim. Acta, 1995, 300, 293) with reactor set at 45°C for methyldopa and at 65°C for dopamine and detection at 473 nm. Calibration graphs were linear up to 20 mM catecholamines with a detection limit of 0.59 µM-dopamine and 0.32 µM-methyldopa; RSD (n = 10) were 0.402 and 0.463%, respectively.
Methyl dopa Dopamine Pharmaceutical Spectrophotometry

"Flow Injection Pervaporation Coupling For The Determination Of Sulfide In Kraft Liquors"
Fresenius J. Anal. Chem. 1996 Volume 354, Issue 4 Pages 442-446
I. Papaefstathiou, M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: A sample that contained sulfide ions was injected or aspirated into a stream (1.3 ml/min) of 1 M TCA of pH 1.16 in advance of a coil (30 cm) and the mixture led into a pervaporation module at 60°C, with a PTFE membrane (5 µm pore) permeable to H2S. The latter was trapped in an upper stream (1.3 ml/min) of 1.92 mM p-diethylaminoaniline in 1 M TCA of pH 1.16 mixed with 3.73 mM ferric ammonium sulfate in 0.044% H2SO4 (0.7 ml/min) and the ethylene blue product monitored at 670 nm. Calibration graphs were linear for 1-15 µg/ml sulfide (injection) or 1-10 µg/ml sulfide (continuous aspiration). Detection limits were 0.68 µg/ml (RSD 5.46%) and 0.42 µg/ml (RSD 8.03%), respectively. Determination of 5 µg/ml sulfide was affected by 5 µg/ml Cd(II); Zn(II), Fe(III), sulfite, carbonate and thiosulfate ions interfered only at 50 orders of magnitude. Sulfide determinations in white and green bleaching liquors agreed quite well with a standard methylene blue procedure.
Sulfides Beverage Industrial Spectrophotometry

"A FIA System For Arsenic(III)/arsenic(V) Determination With Electrochemical Hydride Generation And AAS Detection"
Fresenius J. Anal. Chem. 1996 Volume 354, Issue 7-8 Pages 866-869
Dirk Schauml&ouml;ffel and B. Neidhart

Abstract: Total inorganic As in the carrier stream (1 M H2SO4, 5.4 ml/min) was determined by mixing with 10% L-cysteine solution (1 ml/min), heating in a water bath (95°C) for 40 s and then cooling in ice. The stream passed to the cathode channel of a flow-through cell (described) in which As was converted into AsH3, which was carried in a stream of Ar for determination by AAS. The response was linear for 5-50 µg/l of As(III), with a detection limit of 0.4 µg/l, for 1 mL samples.
Arsenic Arsenic(3+) Arsenic(5+) Spectrophotometry

"Online Column Preconcentration For The Determination Of Cobalt In Seawater By Flow Injection Chemiluminescence Detection"
Fresenius J. Anal. Chem. 1996 Volume 355, Issue 5-6 Pages 676-679
Shizuko Hirata, Yukimasa Hashimoto, Masato Aihara and G. Vitharana Mallika

Abstract: Seawater (100 ml) was adjusted to pH 3.6 with 0.5 mL formic acid/ammonium formate buffer then passed through a fluoride-containing metal alkoxide glass column (3 cm x 4 mm i.d.) of 8-quinolinol immobilized on silica gel for 2 min at a flow rate of 3 ml/min, with 0.05 M HCl as carrier stream at a flow rate of 1.7 ml/min. Most heavy metals were separated except Fe(III), but it did not interfere when the gallic acid/H2O2 method was used: water was passed through the column to remove alkali and alkaline earth metals, then the eluate was passed in the reverse direction at a flow rate of 1.7 ml/min and mixed with gallic acid and NaOH both flowing at 0.76 ml/min. The mixture was heated to 60°C in a 2 m reaction coil and the chemiluminescence intensity was measured. The calibration graph was linear from 0.6 ng/l to 1 µg/l Co. The detection limit was 0.62 ng/l Co for a 6 mL sample; RSD was 2.1% (n = 10) for 10 ng/l Co(II). Results from the analysis of reference seawater samples agreed with the certified values.
Cobalt Sea Environmental Chemiluminescence

"Flow Injection Determination Of Silver With Spectrophotometric Detection"
Fresenius J. Anal. Chem. 1997 Volume 358, Issue 4 Pages 475-479
A. A. Ensafi and K. Zarei

Abstract: Sample (170 µL) was injected into a stream (8 ml/h) of water which merged with streams (8 ml/h) of 0.8 M peroxodisulfate in 32 mM H2SO4 and of 18 mM 1,10-phenanthroline/0.42 mM gallocyanine and passed through a reaction coil (220 cm x 0.5 mm i.d.) before the absorbance was measured at 540 nm. The optimal temperature was 40°C. Tolerance limits for interfering ions are tabulated. Tolerance to bromide, chloride, iodide and thiosulfate was increased 1000-fold by digestion of sample with concentrated HNO3. The detection limit was 0.001 µg Ag and the analytical range was 0.002-0.7 µg. The RSD (n = 10) at 0.035 and 0.17 µg were 2.8% and 0.9%, respectively. The method was applied to river water after digestion with HNO3/H2SO4 and to panchromatic plates (photographic materials) after treatment with NaOH and digestion of the gelatinous film with HNO3. Results agreed with those obtained by AAS. Calibration graphs were linear.
Silver Plate River Sample preparation Spectrophotometry

"Mercury Speciation By Coupling Cold Vapor Atomic Absorption Spectrometry With Flow Injection Online Preconcentration And Liquid Chromatographic Separation"
Fresenius J. Anal. Chem. 1998 Volume 361, Issue 8 Pages 761-766
Xuefeng Yin, Wolfgang Frech, Erwin Hoffmann, C. L&uuml;dke, Jochen Skole

Abstract: A fully automated system for the direct determination of methylmercury (MeHg), ethylmercury (EtHg), phenylmercury (PhHg), and inorganic mercury (Hg(II)) at the ng/L level is described. It is based on solid phase extraction pre-concentration incorporated in a flow injection (FI) system, high performance liquid chromatography (HPLC) separation, reduction combined with thermolysis and determination by cold vapor atomic absorption spectrometry (CVAAS). For pre-concentration a microcolumn of bonded silica with octadecyl functional groups (C18 reversed phase material) was used as a sorbent for the Hg complexes formed online with ammonium pyrrolidine dithiocarbamate. Retained mercury species are eluted with a methanol-acetonitrile-water mixture and subjected to separation on an octadecyl silane (ODS) column before determination by CVAAS. The sensitivity of organo-mercury determination could be improved by NaBH4 as a reductant combined with a thermolysis step. To perform online measurements the pre-concentration microcolumn was mounted in a pressure-tight casing. Limits of detection for MeHg, EtHg, PhHg, and Hg(II) employing a sample volume of 58.5 mL were 9, 6, 10, and 5 ng/L, respectively. The RSD calculated from 9 repeated measurements was 3.6, 5.5, 10.4, and 7.6% for MeHg, EtHg, PhHg, and Hg(II), respectively. Finally, the application of this method for speciation of Hg in fish and human urine is described.
Mercury(II) Methylmercury ion Phenylmercury Ethylmercury Marine Urine Spectrophotometry HPLC

"Development Of Solid-phase Reactors For Continuous Detection Systems. 1. Continuous Detection System For Determination Of Manganese(II) And Permanganate Ions"
Microchim. Acta 1984 Volume 82, Issue 3-4 Pages 271-289
J. R&uuml;ter and B. Neidhart

Abstract: The reactor comprises a column (25 cm x 3 mm) of PbO2 on Silica gel 60 (18 to 35 mesh), maintained at 95°C, with 0.1 M HNO3 as mobile phase. All cationic oxidation states of Mn are oxidized to MnO4-, which can be measured at 520 nm; however, for trace analysis, the MnO4- are used to restore the color to the leuco form of malachite green (C. I. Basic Green 4), with measurement at 620 nm. The range of application is 10 to 100 ng mL-1, with a detection limit of 10 ng. Tervalent Cr, Ce(IV), V(V), Br- and Cl- interfere.
Manganese(II) Permanganate Spectrophotometry

"Determination Of Phosphorus In Silicate Rocks By Flow Injection Method Of Analysis"
Microchim. Acta 1984 Volume 82, Issue 5-6 Pages 377-383
Rokuro Kuroda, Iwao Ida and Koichi Oguma

Abstract: A 0.1-g sample of powdered rock is fused for 15 min at 1000°C with 0.3 g each of Li2CO3 and H3BO3, the melt is dissolved to 100 mL in 1 M HCl, and a 3 mL portion is diluted to 10 mL with water. A six-way loop valve is used to inject 318 µL of this solution into a carrier stream of 0.3 M HCl (1.5 mL min-1), which meets a stream of 0.13% (NH4)6Mo7O24.4H2O - 0.024% Sb K tartrate solution [containing also tartaric acid and poly(vinyl alcohol)] and one of 0.096% ascorbic acid solution (each 0.75 mL min-1). The mixture is passed through a mixing coil immersed in a water bath at 90°C and then through a water-cooled coil, after which the absorbance is measured at 710 nm vs. air. Two levels of P2O5 (0.123 and 0.247%) have been determined successfully in the presence of 28.5 to 85.6% of SiO2. The method has been applied to eight US and Japanese standard rocks, with generally good agreement with recommended or reported values. Twenty samples can be analyzed in the flow system per hour.
Phosphorus Phosphorus pentoxide Silicate Spectrophotometry

"FIA Fluorimetric Assembly For The Determination Of Noradrenaline Hydrochloride By A Solid-phase Reactor With Immobilized Hexacyanoferrate(III)"
Microchim. Acta 1997 Volume 126, Issue 1-2 Pages 69-72
Salome Laredo Ortiz, Gustavo A. Rivas and Jos&eacute; Mart&iacute;nez Calatayud

Abstract: A portion (155.3 µL) of noradrenaline hydrochloride (I) in 0.1 M HCl was injected into a flow (1.59 ml/min) of 1.5 M NaOH, which passed through a solid-phase reactor (10 cm x 1.5 mm i.d.) packed with Duolite A102D resin-immobilized hexacyanoferrate(III), then through a PTFE tube (185 cm x 0.8 mm i.d.) prior to fluorimetric detection at 512 nm (excitation at 397 nm). The analysis was carried out at 55°C. The calibration graph was linear from 0.5-75 mg/l I, the RSD (n = 17) at 25 mg/l was 0.88% and the sample throughput was 84/h. The relative errors in determinations caused by different amounts of interferents are reported. Recoveries and detection limits are not given. An FIA assembly provided with immobilized hexacyanoferrate(III) is proposed for the fluorimetric determination of noradrenaline hydrochloride. The oxidative reagent is immobilized by means of a strong anion-exchange resin. The FIA manifold is very simple and the calibration graph is linear over the range 0.5-75 mg L-1 noradrenaline hydrochloride with an r.s.d of 0.88% (17 replicates) and a sample throughput of 84 h-1. Foreign compounds such as NaCl, sucrose, lactose and sodium sulfate caused no significant errors. The procedure is applied to the determination of noradrenaline in a medicinal formulation. (13 References)
Noradrenaline hydrochloride Pharmaceutical Fluorescence

"FIA Fluorimetric Determination Of Adrenaline In Pharmaceutical Formulations By Oxidation With Molecular Oxygen"
Microchim. Acta 1998 Volume 128, Issue 3-4 Pages 187-190
A. C&aacute;noves Torres, A. Mellado Romero and J. Mart&iacute;nez Calatayud

Abstract: The fluorimetric determination of adrenaline is carried out in a continuous-flow assembly and by the mol. dissolved oxygen. The sample solution merges with an NaOH stream, then the resulting mixture is heated at 73°C and led to the flow-cell of the fluorimeter. The flow-assembly is very simple and the procedure is quick (107 samples h-1) reproducible (RSD 0.6%), selective, and suitable to be applied to determination of adrenaline in formulations. Calibrations graph are linear over the ranges 0.05-15 and 20-40 mg/L.
Adrenaline Pharmaceutical Fluorescence

"Continuous-flow Potentiometric Determination Of α-amylase Activity In Serum And Urine"
Microchem. J. 1985 Volume 32, Issue 2 Pages 183-190
E. P. Diamandis, A. Papanastasiou-Diamandi, T. K. Christopoulos and T. P. Hadjiioannou

Abstract: α-Amylase was caused to react with a buffered starch solution (pH 6.9) at 40°C for 30 min under controlled continuous-flow conditions, after which the reducing sugars produced were oxidized by IO4-. The consumption of IO4- was monitored continuously with a IO4--sensitive flow-through electrode (details given). The endogenous reducing substances of serum or urine were measured with the same system by incubation of the sample with starch solution (pH 4.7) in the presence of NaF as an α-amylase inhibitor. The difference in the reducing power (as glucose) was used to calculate the α-amylase activity of the samples. Values obtained correlated well with those from an amyloclastic method (r = 0.90 to 0.96).
α-Amylase Blood Serum Urine Electrode Electrode Potentiometry

"Determination Of Osmium(VIII) By Flow Injection Kinetic Methods Using Bromopyrogallol Red And Hydrogen Peroxide"
Microchem. J. 1995 Volume 52, Issue 3 Pages 364-369
Chen X. G., Gong H. P., Zhang Q. and Hu Z.

Abstract: The method was applied to refined ores and chlorination residues. Sample (1 g) was mixed with 3 g Na2CO3 and 1 g MgO, heated at 550°C for 15 min, then fused with 7 g Na2O2 at 700°C for 30 min. The melt was treated with 9 M H2SO4, 30% H2O2 and water and the Os was distilled as OsO4 into dilute NaOH. The distillate was treated with H2SO4, diluted with water and portions (100 µL) were injected into a carrier stream (0.6 ml/min) of sodium acetate/acetic acid buffer of pH 5.7. After reaction with streams (0.6 ml/min) of 0.6 mM bromopyrogallol red and 1.2% H2O2 using a 12 cm mixing coil and 100 cm reaction coil (80°C) of 0.5 mm i.d., the decrease in absorbance was measured at 559 nm. The calibration graph was linear for 4-100 ng/ml Os(VIII) and the detection limit was 3 ng/ml. The RSD were 1.8% and 0.76% for ore and chlorination residues, respectively, and the corresponding recoveries were 97.5-101.3% and 96-101.3%. The sample throughput was 47/h. Interference from Ru(III), Rh(III), Ir(IV), Mn(II) and Cr(III) was eliminated by the distillation step.
Osmium(VIII) Refined Residues Spectrophotometry

"High Performance Liquid Chromatographic Separation And Quantification Of Alanopine And Strombine In Crude Tissue Extracts"
Anal. Biochem. 1984 Volume 139, Issue 2 Pages 413-417
G. B. Fiore, C. V. Nicchitta and W. R. Ellington*

Abstract: Perchloric acid extracts of tissues of marine invertebrates were analyzed by HPLC on a Waters amino-acid column (25 cm x 4.6 mm) packed with strong cation exchanger. The mobile phase was 0.1 M citrate buffer (pH 3.0) at 0.4 mL min-1 and detection was by post-column derivatization with NaClO (at 60°C) and phthalaldehyde in the presence of 2-mercaptoethanol, with subsequent fluorimetry at 418 nm (excitation at 340 nm). Retention times of alanopine (2,2'-iminodipropionic acid) and strombine (2-methyliminodiacetic acid) were 4.7 and 5.4 min, respectively. Response was rectilinear from 0.05 to 0.25 nmol.
Alanopine Strombine Tissue HPLC Fluorescence

"Picomole Analysis Of Glutathione, Glutathione Disulfide, Glutathione S-sulfonate And Cysteine S-sulfonate By High Performance Liquid Chromatography"
Anal. Biochem. 1985 Volume 151, Issue 2 Pages 418-423
Douglas A. Keller and Daniel B. Menzel

Abstract: Glutathione(I), glutathione disulfide(II), glutathione S-sulfonate(III) and cysteine S-sulfonate(IV) were separated by HPLC on a column of Spherisorb 5 SAX strong anion exchanger with non-linear gradient elution with 0 to 30% of 144 mM Li citrate - 1 mM EDTA (pH 5.3) in 5 mM citric acid - 1 mM EDTA; determination was by post-column derivatization with phthalaldehyde and 2-mercaptoethanol at 70°C, and fluorescence detection at 430 to 470 nm (excitation at 305 to 395 nm). The detection limits were 10, 10, 50 and 200 pmol for I, II, III and IV, respectively; the respective recoveries were 102.6, 103.3, 95.5 and 99.7%. The method was applied to the analysis of supernatant solution obtained after homogenization of lung tissue with HClO4.
Glutathione Glutathione disulfide Glutathione S sulfonate S-sulfonatecysteine Lung HPLC Fluorescence

"Lowry Protein Determination By Automated Flow Injection Analysis For Bovine Serum Albumin And Hepatitis B Surface Antigen"
Anal. Biochem. 1985 Volume 151, Issue 2 Pages 309-314
Ronald A. Salerno, Cathy Odell, Nancy Cyanovich, Bernard P. Bubnis, Wayne Morges and Alan Gray

Abstract: The Lowry method for quantitation of protein was adapted to automated flow injection analysis. The procedure was developed using two different pure proteins: bovine serum albumin and hepatitis B surface antigen. The system was optimized for reagent concentration, pH, gain, temperature, sample volume, and output. The response of each protein was affected differently by temperature. The reaction slopes and absorbance values of the proteins were similar at 90°C to allow quantitation of hepatitis surface antigen against bovine serum albumin. Advantages of the automated flow injection analysis Lowry procedure include: rapid analyzes (90 samples/h), small sample volume (30 µL, 100 µL), fast response (20 s), reproducibility (less than or equal to 2% CV within an assay and 3 to 6% CV among assays), sensitivity (5 µg), and high correlation (99.8%) with manual assay. After a 30-min set-up period, the analyzer was available to assay protein on demand throughout the day, making it suitable for process and quality control testing. Bovine serum albumin(I) or hepatitis B surface antigen(II) was determined by the Lowry method adapted for use with flow injection analysis. The sample was mixed with the alkaline tartrate copper reagent and heated at 90°C in a reaction coil (100 cm x 0.7 mm). The solution was mixed with Folin - Ciocalteu reagent in a second reaction coil (60 cm x 0.5 mm) and the absorbance of the mixture was measured at 600 nm. The pH was 10.5. The calibration graphs were rectilinear for 10 to 80 and 10 to 40 µg mL-1 of I and II, respectively, and the limit of detection was 5 µg mL-1; the within- and between-assay coefficient of variation were 2 and 3 to 6%, respectively. The results correlated well (r = 0.998) with those obtained by the manual method.
Proteins Albumin Cow Serum Spectrophotometry

"Fluorimetric Determination Of Guanidino-compounds By New Post-column Derivatization System Using Reversed-phase Ion-pair High Performance Liquid Chromatography"
Anal. Biochem. 1987 Volume 160, Issue 2 Pages 392-398
Yoshie Kobayashi, Hiroaki Kubo and Toshio Kinoshita

Abstract: Nine guanidino-compounds and creatinine in serum were separated in 25 min by reversed-phase ion-pair HPLC with post-column derivatization on a column (15 cm x 4.6 mm) of Nucleosil C8 (5 µm). The mobile phase (1 mL min-1) was 1 mM Na 1,2-naphthoquinone-4-sulfonate (fluorogenic reagent) and 15 mM Na octanesulfonate in water - acetonitrile - methanol (92:3:5) adjusted to pH 4.0 or 3.5 with acetic acid; 1 M NaOH was delivered at 0.5 mL min-1 to a reaction coil (5 m x 0.5 mm) and the fluorescent products formed were detected at 505 nm (excitation at 355 nm). The detection limit was <20 ng and recovery from serum was 93 to 108%. The method was accurate and reproducible and could be used for routine determinations in haemodialysis patients. Guanidino-drugs could also be determined by using this system.
Drugs Guanidino compounds Blood Serum HPLC Fluorescence

"Measurement Of Protein Using Flow Injection Analysis With Bicinchoninic Acid"
Anal. Biochem. 1987 Volume 161, Issue 1 Pages 152-156
Lawrence C. Davis* and Gary A. Radke

Abstract: The bicinchoninic acid reagent developed by Pierce Chemical Co. was used in the determination of proteins in a flow injection analyzer comprising ~8 ft of PTFE tubing (0.5 mm i.d.) with a peristaltic pump, a controlled-temperature water bath (reaction temperature was 72°C), and a spectrophotometer with flow cell. The sensitivity was comparable with that of the Lowry method. Results were obtained in <1 min at a rate of up to 60 h-1. Sample size was 5 to 20 µL and the response was rectilinear up to 10 µg of protein. We have used the bicinchoninic acid reagent developed by Pierce Chemical Co. to measure proteins in a simple flow injection analyzer. The sensitivity is comparable to that of the Lowry method and no pipetting of reagents is needed. Results are obtained in less than 1 min and samples may be run at a rate of 60/h. The response is linear over a range of protein concentration (0-10 µg) and sample size (5-20 µL) convenient for most analytical requirements. A peristaltic pump, a controlled-temperature water bath, and a spectrophotometer with flow cuvette are the only special apparatus required.
Proteins Industrial Pharmaceutical Spectrophotometry

"Liquid Chromatographic Determination Of Amino-acids Using A Hollow-fiber Membrane Reactor"
Anal. Biochem. 1988 Volume 171, Issue 2 Pages 398-403
Jun Haginaka* and Junko Wakai

Abstract: Eighteen common amino-acids were determined by HPLC on a column (30 cm x 4.6 mm) of Develosil ODS-5 (5 µm) with a guard column (3 cm x 4.6 mm) of the same packing material. The mobile phase (0.8 mL min-1) was a five-step gradient (described) from 0 to 80% of 15 mM Na octanesulfonate - 21 mM H3PO4 - 9 mM NaH2PO4 - methanol (1:1:1:6; pH 4.2 in 20:20:20:1; pH 2.8). Post-column derivatization was carried out at 60°C by reaction with phthalaldehyde and 2-mercaptoethanol (combined with hypochlorite oxidation for proline), introduced into the main stream with use of sulfonated and aminated hollow-fiber membrane reactors, respectively. Derivatives were detected fluorimetrically at 450 nm (excitation at 340 nm). Detection limits were 0.4 to 20 pmol for the 18 amino-acids. The method was applied in the determination of amino-acids in protein hydrolysates.
Amino Acids HPLC Fluorescence

"Immobilization Of Linamarase And Its Use In The Determination Of Bound Cyanide In Cassava Using Flow Injection Analysis"
Anal. Biochem. 1988 Volume 172, Issue 1 Pages 89-95
D. Narinesingh*, D. Jaipersad and I. Chang-Yen

Abstract: β-Glucosidase was immobilized (details given) on 2-fluoro-N-methylpyridinium-activated Fractogel support; the gel was washed and packed in nylon columns (5 cm x 2 mm) for use in flow injection analysis. Cassava leaves or tubers were extracted with H3PO4, the extracts were filtered under vacuum and the filtrates were adjusted to pH 7.2 with 1 M NaOH and centrifuged at 3000 rpm for 5 min. Portions (90 µl) of the supernatant solution were injected into the flow injection system, at 30°, and passed (0.33 mL min-1) into the reactor column, or a blank column to correct for free CN-. The solution were then mixed with picrate reagent of pH 10.8 and passed through a coil at 85°C and the absorbance of the complex formed was measured at 525 nm. The calibration graph was rectilinear, for both free CN- and CN- liberated from linamarin, from 1 to 10 mM; the detection limit was 67 ppm. Interference from glucose and acetone was negligible. Extracts from the tubers (cortex and parenchyma) and leaves of Manihot esculenta Crantz (cassava) were analyzed for their releasable cyanide content using flow injection analysis incorporating an immobilized linamarase bioreactor. Linamarase was immobilized under very mild conditions to an activated 2-fluoro-N-methylpyridinium Fractogel support. The released cyanide, which was monitored spectrophotometrically at 525 nm using an alkaline picrate reagent, was found to be highest in the cortex and lowest in the parenchyma.
Cyanide Leaves Tubers Sample preparation Spectrophotometry

"Determinations Of Lactate And Lactate Dehydrogenase Activity In Serum With The Flow Injection Analysis System Involving Immobilized Enzyme Column And Chemiluminescence"
Anal. Biochem. 1991 Volume 193, Issue 1 Pages 112-117
Masayoshi Tabata, Masayuki Totani* and Takashi Murachi

Abstract: The methods for the highly sensitive flow injection analysis of lactate and lactate dehydrogenase (LDH) activity in serum using immobilized enzymes in column form and chemiluminescence detection which does not require a blank correction are described. The methods were based on the determination of chemiluminescence formed by the reaction of a luminol-ferricyanide mixture with hydrogen peroxide. This hydrogen peroxide was produced by the lactate oxidase (LOD) reaction from lactate, which was in serum or was produced by the action of LDH in serum. The action of LDH in a flow injection analysis system was performed for 2 min in an incubation coil placed parallel to the substrate-buffer line between the LOD column and the LOD/catalase column. Endogenous lactate in serum was removed by an immobilized LOD/catalase column prior to the action of LDH. The present method gave perfect linearity of the data up to 5.6 mmol/liter for lactate and 1840 IU/liter for LDH activity with satisfactory precision, reproducibility, and accurate reaction recoveries. The results from the lactate and LDH activity correlated satisfactorily with those obtained by other well-established methods. Serum was applied to a column of lactate oxidase - catalase immobilized on alkylamine glass beads. The eluate was incubated at 37°C for 2 min with phosphate buffer solution (pH 7.5) containing pyruvate and NADH. The mixture was applied to a lactate oxidase column and the eluate was subjected to chemiluminometric determination (J. Appl. Biochem., 1984, 6, 251). Lactate in serum was determined as above but the sample was applied directly on to the lactate oxidase column. The calibration graph was rectilinear for 5.6 mM lactate and the detection limit was 10 µM. For lactate dehydrogenase, the calibration graph was rectilinear for 1840 IU L-1 and the within- and day-to-day coefficient of variation were 3.0 and 3.9%, respectively. The results correlated well (r = 0.974) with those obtained on a Hitachi Model 726 discrete automatic analyzer. with use of pyruvate as substrate.
Lactate Enzyme, lactate dehydrogenase Blood Serum Chemiluminescence

"Flow Injection Analysis Of Lactose Using Covalently Immobilized β-galactosidase, Mutarotase, And Glucose Oxidase/peroxidase On A 2-fluoro-1-methylpyridinium Salt-activated Fractogel Support"
Anal. Biochem. 1991 Volume 194, Issue 1 Pages 16-24
Dyer Narinesingh, Valerie A. Stoute, Gershwin Davis and That T. Ngo

Abstract: Milk samples were analyzed for their lactose content using flow injection analysis and incorporating immobilized β-galactosidase or β-galactosidase/mutarotase and glucose oxidase/peroxidase bioreactors. These enzymes were immobilized, under mild conditions, on to a 2-fluoro-1-methylpyridinium salt-activated Fractogel support. The use of a phosphate buffer (0.15 M) was found to facilitate the rapid mutarotation of α-D-glucose and hence could obviate the need for the more expensive mutarotase. The chromogenic agents of choice for monitoring the reaction were 3-methyl-2-benzothiazolinone hydrazone and 3-dimethylaminobenzoic acid. Linearity was observed over the concentration range 16-160 µg/ml using lactose standards (r = 0.996). Between 30 and 40 milk samples/h can be analyzed. Comparisons are made with existing HPLC and alkaline methylamine methods for a range of milk matrices. The FIA method consistently gives the lowest standard deviations and coefficient of variation for the various milk matrices analyzed. Milk was incubated at 25°C for 10 min with concentrated HCl and then gravity-filtered. The filtrate was adjusted to pH 6.5 and mixed with 3-dimethylaminobenzoic acid and 3-methyl-2-benzothiazolinone hydrazone in phosphate buffer solution (pH 6.5). The mixture was subjected to flow injection analysis at 33°C on a column of β-galactosidase in series with a bioreactor of glucose oxidase - peroxidase, with detection at 590 nm. The calibration graph was rectilinear for 160 µg mL-1 of lactose and the coefficient of variation was 2.7 to 3.8% (n = 3). Between 30 and 40 samples per h can be analyzed.
Lactose Milk Spectrophotometry

"Reversed-phase Ion-pair High Performance Liquid Chromatography Method For Bovine Testicular Hyaluronidase Digests Using Post-column Derivatization With 2-cyanoacetamide And Ultra-violet Detection"
Anal. Biochem. 1991 Volume 196, Issue 1 Pages 183-191
Jeffrey A. Cramer and Leonard C. Bailey

Abstract: Bovine testicular hyaluronidase was incubated with hyaluronic acid hexasaccharide, at 37°C. After addition of the mobile phase [0.03 M tetrabutylammonium hydroxide (pH 9.0) - acetonitrile (4:1)], the mixture was subjected to HPLC on a column (15 cm x 4.1 mm) of Hamilton PRP-1 polymeric C18. The mobile phase flow rate was 0.8 mL min-1 and the eluant was mixed with 1% 2-cyanoacetamide in 0.2 M Na borate buffer (pH 9.0) for 2 min at 100°C before cooling and detection at 276 nm. The calibration graphs were rectilinear for 10 to 400 nmol of C-4 and C-6 oligomers and the coefficient of variation were 1.5 to 5.7%.
HPLC Spectrophotometry

"Determination Of Serum Cholinesterase Activity By Liquid Chromatography With Electrochemical Detection"
Anal. Biochem. 1991 Volume 196, Issue 2 Pages 377-384
R. Brent Miller and C. LeRoy Blank

Abstract: Serum was incubated at room temperature for 10 min in phosphate buffer solution (pH 7.2) containing ethylhomocholine, choline and acetylcholine. After addition of HClO4 and centrifugation, the supernatant solution was subjected to HPLC on a C18 (3 µm ODS) column (10 cm x 3.2 mm). The mobile phase (0.9 mL min-1) was Tris buffer solution (pH 7.5) containing acetic acid, tetramethylammonium chloride, Na octyl sulfate, NaN3, EDTA and acetonitrile. Post-column derivatization was effected with choline oxidase and acetylcholinesterase with electrochemical detection at 0.5 V vs. Ag - AgCl. The limit of detection was 3 pmol of choline or 0.1 µmol mL-1 h-1 of cholinesterase. The calibration graph was rectilinear for up to 269 µmol mL-1 h-1, with a coefficient of variation of 1.7%.
Enzyme, cholinesterase Blood Serum HPLC Electrochemical analysis

"High Performance Liquid Chromatographic Determination Of Pyrophosphate In The Presence Of A 20,000-fold Excess Of Orthophosphate"
Anal. Biochem. 1991 Volume 199, Issue 2 Pages 279-285
Norimasa Yoza, Izumi Akazaki, Tetsuya Nakazato, Nobuyuki Ueda, Hiroki Kodama and Akira Tateda

Abstract: Mixed samples of orthophosphate (I) and pyrophosphate (II) (100 µL) were injected into the carrier stream of 0.23 M or 0.18 M KCl and 0.1% Na4EDTA (1 mL min-1) and was passed through a column (25 cm x 4 mm) of TSK-gel SAX (10 µm). The eluate was mixed with a reagent stream (0.5 mL min-1) of Mo(V) - Mo(VI) for reaction in a reaction coil (15 m x 0.5 mm) of PTFE at 140°C. The cooled mixture was analyzed at 330 to 800 nm. The presence of a 20,000-fold excess of I did not interfere seriously. The working range was from 0.3 to 500 µM I and II, with coefficient of variation of 2 to 10%.
Pyrophosphate HPLC

"Semi-automated Flow Injection Procedure For Acetylcholinesterase And Cholinesterase Activities"
Anal. Biochem. 1992 Volume 200, Issue 1 Pages 176-179
Ignacio L&oacute;pez Garc&iacute;a, Fernando Ruiz Abell&aacute;n and Manuel Hern&aacute;ndez C&oacute;rdoba

Abstract: A stopped-flow flow injection method is described (details and diagram of apparatus given) for the assay of cholinesterase (I) and acetylcholinesterase (II) based on the Ellman colorimetric method. For determination of I, serum (100 µL) was diluted to 10 mL with phosphate buffer solution For determination of II, 25 µL of blood was mixed with 1 mL of isotonic saline. The erythrocytes, pelleted by centrifugation, were haemolysed in 1 mL of water and the haemolysate was analyzed. Sample solution (50 µL) was injected into a carrier stream (0.1 mL min-1) comprising 2 mM acetylthiocholine and 0.2 mM 5,5'-dithiobis-(2-nitrobenzoic acid) in 0.1 M phosphate buffer solution (pH 7.2) and the resulting stream was passed through a 46 cm reaction coil at 37°C to a flow cell where the flow was stopped to allow detection at 410 nm. The calibration graphs for I and II were rectilinear and the FIA was significantly more sensitive than the manual procedure. A stopped-flow FIA adaptation of the classical Ellman's colorimetric procedure for the measurement of acetylcholinesterase or cholinesterase activity is described. The samples are injected into a flow analytical system which is provided with an electronic timer and an electrovalve in order to stop the flow when the sample is inside the measurement cell. In this way, the absorbance-time relationship is obtained with a savings of sample, time, and reagents.
Acetylcholinesterase Enzyme, cholinesterase Blood Serum Blood Spectrophotometry

"Solubilized Substrates For The Online Measurement Of Lipases By Flow Injection Analysis During Chromatographic Enzyme Purification"
Anal. Biochem. 1992 Volume 202, Issue 1 Pages 16-24
Gabriele C. Chemnitius, Helmut Erdmann* and Rolf D. Schmid

Abstract: A modular flow injection system was applied in the online assay of lipases. Substrate emulsion and lipase solution were simultaneously injected into carrier stream 1 and carrier stream 2, respectively, the carrier streams were combined and passed through a thermostated reaction coil before being passed to the photometer. 1,2-O-didodecyl-rac-glycero-3-glutaric resorufin ester was the preferred substrate with a reaction coil temperature of 37°C. With a combination of stopped-flow technique and zone sampling and detection at 571 nm, calibration graphs were rectilinear up to 800 IU mL-1 of lipase from Staphylococcus carnosus. Results for lipases from other species are presented. A flow injection analysis (FIA) system for the online measurement of lipases in chromatography processes was developed. The photometrically detectable substrates, p-nitrophenyl palmitate, S,O,O'-tripropyryl-1-thioglycerol, and 1,2-O-dilauryl-rac-glycero-3- glutaric resorufin ester were investigated. Different detergents and qualities of assay emulsions were tested for optimal results in FIA applications. Emphasis was placed on increasing the stability of the assay emulsion. Lipases of different origin and specificity were detected. The linear detection range was adapted to the requirements of the chromatography purifn. procedures. The connection of the FIA with a fast-protein liquid chromatography system permitted the automatization of lipase purifn. by monitoring protein content, salinity, and enzyme activity of the effluent from column chromatography.
Enzyme, lipase LC Spectrophotometry

"Direct Determination Of Glucose In Blood Serum Using Trinder's Reaction"
Anal. Lett. 1984 Volume 17, Issue 5 Pages 385-396
M. J. Medina; J. Bartroli; J. Alonso; M. Blanco; J. Fuentes

Abstract: A flow injection analysis system (illustrated schematically) is described; the method is based on Trinder's reaction, which is a two-stage process with oxidation of β-D-glucose by glucose oxidase to produce H2O2 followed by peroxidase-catalyzed oxidative coupling to form a colored quinonimine dye. Serum (15 µL) is injected directly into water as carrier (0.5 mL min-1) without deproteinization or dialysis and dispersed in a 1-m coil before mixing with a stream of enzyme solution (12 iu mL-1 of glucose oxidase, 1.2 iu mL-1 of peroxidase, 1.5 mM 4-aminoantipyrine and 100 mM phosphate buffer of pH 7.0) and one of 9.3 mM phenol (each at 0.5 mL min-1). Reaction occurs in a single bead string reactor (length 1 m) at 37°C, and the solution then passes through a 1-m coil at 37°C before detection at 505 nm. Calibration graphs are rectilinear in the range 50 to 400 mg dl-1 and sampling frequency is 60 h-1.
Glucose Blood Serum Spectrophotometry

"New Simultaneous Catalytic Determination Of Thiocyanate And Iodide By Flow Injection Analysis"
Anal. Lett. 1985 Volume 18, Issue 6 Pages 695-705
Akira Tanaka; Masumi Miyazaki; Toshio Deguchi

Abstract: The method is based on the selective inactivation of SCN- and the SCN-- and I--catalyzed redox reaction between Ce(IV) and As(III). The inactivation of SCN- and I- after mixing with Ce(IV) in the absence of As, and the restoration of catalytic activity of I- only after adding excess of As(III), were first established. The flow injection analysis system contained two simultaneous reaction facilities at 50°C; in system(I), aqueous sample solution was carried (3.0 mL min-1) into a mixture of 5 mM Ce(IV) and 80 mM As(III) (1.0 mL min-1), where a catalyzed reaction occurred. In system(II), sample solution in the sample loop was pre-treated with 5 mM Ce followed by an excess of 80 mM As. The solution was then allowed to react catalytically with Ce(IV) - As(III). Decreases in the absorbance of Ce(IV) at 254 nm were monitored. Amounts of SCN- and I-, and I- only, were thus determined in(I) and (iii), respectively. All calibration graphs showed good rectilinearity and the detection limits were 0.2 ppm of SCN- and 0.1 ppm of I-. The sampling rate was 20 h-1. Osmium, Mn, Fe, Mg, Hg and Ag interfered.
Iodide Thiocyanate ion Spectrophotometry

"Potentiometric Flow Injection Determination Of Sugar Using A Metallic Copper Electrode"
Anal. Lett. 1985 Volume 18, Issue 16 Pages 1953-1978
Alexander, P.W.;Haddad, P.R.;Trojanowicz, M.A.

Abstract: The reducing sugar sample solution is injected into a water stream and reacted with a stream of carrier solution containing Cu(II) and NH3 or Na tartrate in a heated coil of PTFE tubing (70 to 250 cm x 0.5 mm). The reduction of the Cu(II) by the sugars is monitored at a copper electrode; sensitivity is highest at low flow rates (e.g., 1 mL min-1) and high temperature (e.g., 100°C). The method was also used in the analysis of 100 µL aliquots of a solution containing maltose, glucose, sorbose and fructose (25 mM each) by cation-exchange HPLC on Sugar-Pak I with water as mobile phase (0.3 mL min-1) and post-column derivatization with 0.5 mM CuSO4 and 50 mM NH3 at pH 10 (0.5 mL min-1).
Carbohydrates Fructose Glucose Maltose Sorbose HPIC Electrode Potentiometry

"Fluorimetric Determination Of Pyridoxal And Pyridoxal-5-phosphate By Flow Injection Analysis"
Anal. Lett. 1985 Volume 18, Issue 1 Pages 67-78
P. Linares; Luque de Castro; M. Valc&aacute;rcel

Abstract: Both compounds were determined after oxidation in the presence of cyanide. Sample solution were injected (120.4 µL) and were mixed with phosphate buffer, pH 7.43, and cyanide at 45°C. Pyridoxal was then measured directly after 435 nm (excitation at 355 nm). The response was rectilinear over the range 25 nM to 1 mM (with suitable adjustment of instrument sensitivity). NAD could be tolerated in up to 100-fold molar excess, but pyridoxal 5'-phosphate only in equal amounts. Pyridoxal 5'-phosphate was measured at 420 nm (excitation at 325 nm) after addition of 0.2 M HCl to the reaction mixture. The working range was similar to that for pyridoxal. The presence of pyridoxal can be tolerated up to 10-fold and NAD up to 60-fold molar excess.
Pyridoxal Pyridoxal phosphate Fluorescence

"Determination Of Paracetamol By A Flow Injection Spectrophotometric Method"
Anal. Lett. 1986 Volume 19, Issue 19&20 Pages 2023-2038
Martinez Calatayud, J.;Pascual Marti, M.C.;Sagrado Vives, S.

Abstract: Tablets are dissolved with water, the solution is made 0.4 M in aqueous NH3 and paracetamol (I; 0.25 to 30 ppm) is determined by oxidation at 80°C with K3Fe(CN)6 to form N-acetyl-p-benzoquinonimine. The compound is then caused to react with phenol to form N-(4-hydroxyphenyl)-p-benzoquinonimine and the absorbance of the blue solution is measured at 630 nm. For 10 ppm of I, salicylic acid, phenobarbitone, citric acid, diazepam, phenylephrine, aspirin, caffeine, and aged ascorbic acid solution do not interfere at levels from 50 to 250 ppm. The proposed method was applied to the determination of I in various pharmaceuticals.
Drugs Acetaminophen Pharmaceutical Spectrophotometry

"Determination Of Ppb Levels Of Formaldehyde In Aqueous Solution By Ion Chromatography With Post-column Derivatization"
Anal. Lett. 1988 Volume 21, Issue 2 Pages 253-263
McClure, J.E.

Abstract: An aqueous solution of formaldehyde(I) was injected into a cation-exchange column of Dionex 30888 (K+ form) and I was eluted (0.8 mL min-1) with 0.05 M H2SO4 - 0.05 M K2SO4. The eluate then passed to a mixing chamber where it was mixed with aqueous 6.25% ammonium acetate - 0.75% acetic acid - 0.5% acetylacetone and thence to a reaction coil heated at 90°C in a water bath. After cooling the solution to room temp., the absorbance was measured at 420 nm. The limit of detection was 5 µg l-1, response was rectilinear up to 10 mg L-1 of I and the coefficient of variation (n = 7) was 0.6%. The method was applied to determine I in the presence of high concentration. of other aldehydes.
Formaldehyde HPIC Spectrophotometry

"An Aromatic Phosphine Reagent For The HPLC - Fluorescence Determination Of Hydroperoxides. Determination Of Phosphatidylcholine Hydroperoxides In Human Plasma"
Anal. Lett. 1988 Volume 21, Issue 6 Pages 965-975
Akasaka, K.;Ohrui, H.;Meguro, H.

Abstract: A mixture of plasma (0.5 ml), methanol (0.5 ml) and CHCl3 (1 ml) containing 0.003% of 2,6-di-t-butyl-p-cresol (solvent A) was shaken vigorously and centrifuged at 1000 g for 10 min. The CHCl3 layer was separated, and the aqueous phase was extracted with solvent A (2 x 1 ml). The combined CHCl3 solution were evaporated, the residue was dissolved in solvent A (15 µL), and a 10 µL portion was analyzed by HPLC. A column (25 cm x 4.6 mm) of TSK-gel silica 60 was used, with CHCl3 - methanol - water (9:21:1) as mobile phase (0.6 mL min-1), and detection at 235 nm. The eluate was mixed (0.3 mL min-1) with a solution of 3 mg of diphenyl-1-pyrenylphosphine(I) in 400 mL of methanol - acetone (3:1), in a stainless-steel coil (10 m x 0.25 mm) at 70°C. The mixture was then passed through a 0.5-mm i.d. coil in a water bath at 20°C, and the resulting I oxide was detected fluorimetrically at 380 nm (excitation at 352 nm). The peak height ratio of phosphatidylcholine hydroperoxides to phosphatidylcholine (internal standard) was rectilinearly related to concentration. up to 60 pmol in 0.5 mL of plasma; the coefficient of variation (n = 5) was 5%.
Phosphatidylcholine Plasma Human HPLC Fluorescence

"Flow Injection Spectrophotometric Determination Of Sodium Nitroprusside"
Anal. Lett. 1991 Volume 24, Issue 4 Pages 589-601
Abdulaziz M. Al-Wehaid

Abstract: The test solution (100 µL) was injected into a stream (0.15 mL min-1) of 0.25 M NaOH that then passed through a 50-cm coil at 75°C wherein NO2- was liberated from the sodium nitroprusside. The solution then merged with a stream (0.15 mL min-1) of a solution of 20 g L-1 of sulfanilamide and 0.5 g L-1 of N-(1-naphthyl)ethylenediamine dihydrochloride in 0.4 M HCl. The mixture was passed through a 50-cm reaction coil before measurement of the absorbance of the resulting azo-dye at 530 nm. The calibration graph was rectilinear for up to 0.1 mM sodium nitroprusside, and the coefficient of variation at 0.01 mM was 2.8% (n = 10). A range of added substances caused no interference. The method was applied to ampoule contents.
Nitroprusside Spectrophotometry

"Determination Of Amikacin In Dog Plasma By Reversed-phase Ion-pairing Liquid Chromatography With Post-column Derivatization"
Anal. Lett. 1992 Volume 25, Issue 7 Pages 1235-1250
Sar, F.;Leroy, P.;Nicolas, A.

Abstract: Plasma (1 ml) was vortex-mixed with 0.1 mL of 50 mM Na2SO4 (pH 3.5) and 0.5 mL of 10% trichloroacetic acid for 15 s and the mixture was centrifuged at 5°C and 2000 g for 10 min. A 100 µL portion of the supernatant solution was subjected to HPLC on a column (12.5 cm x 4 mm) of LiChrospher RP 18, operated at 45°C, with a mobile phase (1.5 mL min-1) of (50 mM Na2SO4 and 5 mM sodium octylsulfate at pH 3.5) - methanol (7:3). The eluate was merged with a stream (0.3 mL min-1) of phthalaldehyde - 2-mercaptoethanol reagent (details given) before fluorimetric detection at 415 nm (excitation at 340 nm). The calibration graph was rectilinear from 0.1 to 2 µg mL-1 of amikacin (I); the detection limit was 25 ng mL-1. Recoveries ranged from 99.5 to 105%. The intra- and inter-day coefficient of variation for 0.2 µg mL-1 of I were 4.7 and 5.6%, respectivley. A pharmacokinetic study is reported.
Amikacin Blood Plasma HPLC Fluorescence

"Spectrophotometric Determination Of Palladium By Microwave FIA"
Anal. Lett. 1994 Volume 27, Issue 4 Pages 793-805
Xu, Y.J.;Hu, Z.D.

Abstract: In the cited FIA system (diagram given) samples (392.4 µL) and reagent [127.5 µL of 141 µM-2-(4-chloro-2-phosphonophenylazo)-7-(3-nitrophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (chlorophosphonazo-mN)] were injected into a stream (1.78 ml/min) of 10 mM H2SO4 and carried to a reaction coil (10 m x 0.5 mm i.d.), 7 m of which was situated in a microwave oven operated for 30 s at 553 W. Formation of the blue complex was monitored at 615 nm (ε = 18 200); the sampling frequency was 20/h. Beer's law was obeyed from 2-10 µg/ml of Pd and the detection limit was 1 µg/ml; the RSD was 5.6% and the recovery was 95%.
Palladium Environmental Spectrophotometry Sample preparation

"Determination Of Sodium Nitroprusside By Flow Injection With Spectrophotometric Detection"
Anal. Lett. 1995 Volume 28, Issue 2 Pages 295-306
Alwarthan, A.A.

Abstract: Samples (150 µL) were injected into a carrier stream (0.72 ml/min) of 0.15 M NaOH which merged with a stream (0.72 ml/min) of 5 mM sulfadiazine in 0.5 M HCl before passing to a reaction coil (150 cm x 0.8 mm i.d.) maintained at 70°C, where nitrite ions liberated from sodium nitroprusside (I) were diazotized. After merging with a stream (0.72 ml/min) of 0.1 mM N-(1-naphthyl)ethylene-diamine dihydrochloride in 0.5 M HCl, the solution passed through a second reaction coil (100 cm x 0.8 mm i.d.) where coupling occurred and the absorbance of the resulting purple azo dye was measured at 545 nm. Beer's law was obeyed from 0.1-100 µg/ml of I and the detection limit was 0.05 µg/ml. The RSD at 10 µg/ml I was 1.78%. Sample throughput was 17.5/h. Glucose and riboflavin interfered. The method was applied to a pharmaceutical preparation. Ampoule contents (50 mg I were dissolved in and diluted to 250 mL with 0.15 M NaOH; the recoveries were 99.5-100.25%.
Nitroprusside Pharmaceutical Spectrophotometry

"FIA Fluorimetric Determination Of Calcium Pantothenate. Validation And Quantitation In Multivitamin Preparations"
Anal. Lett. 1995 Volume 28, Issue 5 Pages 821-833
Blanco, M.;Coello, J.;Iturriaga, H.;Maspoch, S.;Pages, J.

Abstract: Powdered tablets were suspended in 0.02 M HCl, sonicated for 10 min and centrifuged. The resulting solution was appropriately diluted and injected (35 µL) into the flow injection manifold (diagram given). Calcium pantothenate (I) was hydrolyzed in a 10 m loop by mixing with 0.6 M NaOH (0.9 ml/min) and heating at 85°C. Following hydrolysis, the solution was mixed with the derivatization solution (1 ml/min) comprising 0.373 mM o-phthaldialdehyde 38 µM-2-mercaptoethanol and 0.4 M H3BO3 in a 3 m coil. The emitted fluorescence was measured at 455 nm (excitation at 350 nm). The calibration graph was linear from 0.2-40 mg/l of I. The sampling rate was 25 samples/h. Detection and quantitation limits were 0.02 and 0.09 mg/l, respectively. The method was applied to multivitamin preparations.
Pantothenate Pharmaceutical Fluorescence

"Direct Spectrophotometric Determination Of Platinum By Microwave-oven Induced Flow Injection Analysis"
Anal. Lett. 1995 Volume 28, Issue 12 Pages 2227-2238
Li, G.B.;Xu, Y.J.;Chen, X.G.;Hu, Z.D.

Abstract: A microwave-oven induced flow injection analyzer. was developed (schematic given). Sample (200 µL) containing Pt(II) or (IV) was injected into a water carrier stream (2.05 ml/min) between two parts of reagent by a 16-way valve. The reagent used was 0.6 mM 5-(5-bromo-2-pyridylazo)-2,4-diaminotoluene in acetic acid/sodium acetate buffer (400 µL). After the sample had flowed entirely (15 s) into the microwave oven in a reaction coil (9 m x 0.5 mm), the microwave oven was switched on. The microwave power (70-700 W) and the irradiation time (0-99 s to 0-99 min) was microprocessor controlled. After the reaction, the mixture was passed through a cooling coil to a spectrophotometer. The maximum absorption wavelength was 600 nm for the Pt(II) complex and 560 nm for the Pt(IV) complex. Beer's law was obeyed from 2-25 µg/ml of Pt(II) (ε = 7800) with a detection limit of 3 µg/ml. Equal concentration of Co2+, Pd2+, Ru3+, Rh3+ and Ir2+ interfered seriously. The method was used to determine Pt in industrial Pt catalysts on Al supports.
Platinum Platinum Spectrophotometry

"Kinetic Flow Injection Spectrophotometric Determination Of Nitrite By Its Catalytic Effect On The Oxidation Of Chlorophosphonazo-pN By Bromate"
Anal. Lett. 1996 Volume 29, Issue 11 Pages 2015-2023
Chen Xingguo; Wang Ketai; Hu Zhide; Zhao Zhengfeng

Abstract: Sample (120 µL) was injected into the carrier stream (H2O; 0.8 ml/min) and mixed in a mixing coil (12 cm length) with 2-(4-chloro-2-phosphonophenylazo)-7-(4-nitrophenylazo)-1,8- dihydroxynaphthalene-3,6-disulfonic acid/H2SO4 (0.8 ml/min). The resulting stream was merged with 6 mM KBrO3 (1-2 ml/min) in a reaction coil (100 cm length) at 80°C. The resulting decrease in absorbance was monitored with a 1 cm path flow cell at 551 nm. The sampling frequency was 83 samples/h. The calibration graph was linear from 0.05-1 µg/ml of nitrite with a detection limit of 0.018 µg/ml. Chloride interference could be removed by precipitation with AgNO3. The RSD (n = 7) was 1% at the 1 µg/ml level (based on peak height). The method was applied to the determination of nitrite in water and soil.
Nitrite Environmental Environmental Spectrophotometry

"Stopped-flow Spectrophotometric Determination Of Dopamine And Methyldopa With Sodium Hydroxide"
Anal. Lett. 1997 Volume 30, Issue 6 Pages 1109-1120
Juan J. Berzas; Jos&eacute; M. Lemus; Prado Buitrago

Abstract: Sample (350 µL) was injected into a water carrier stream and merged with 0.6 M NaOH (0.6 ml/min) at 60°C. A schematic diagram of the stopped-flow manifold is given. The resulting solution passed into a reactor (1 m x 0.5 mm i.d.) and the solution passed into a flow cell (1.25 ml/min). Thirty seconds after the sample injection, the pump was stopped manually and the variation of the absorbance at 360 nm was monitored throughout the reaction. Calibration graphs were linear up to 0.2 mM dopamine and 0.3 mM methyldopa, respectively. The corresponding detection limits were 3.5 µM and 0.43 µM. The method was applied to the determination of the catecholamines in pharmaceutical formulations.
Methyl dopa Dopamine Catecholamines Pharmaceutical Spectrophotometry

"Amperometric Flow Injection Analysis Of L-glutamate Using An Immobilized-enzyme Reactor: Amplification By Substrate Recycling"
Electroanalysis 1990 Volume 2, Issue 7 Pages 563-565
Toshio Yao*, Naokazu Kobayashi, Tamotsu Wasa

Abstract: A column (5 mm x 4 mm i.d.) of LiChrosorb NH2 (10 µm) was activated by circulation of 5% glutaraldehyde solution in 0.05 M NaHCO3 for 1.5 h, then washed with 0.1 M phosphate buffer of pH 7.0 before co-loading with glutamate oxidase (8.5 iu) and alanine aminotransferase (118 iu) by circulation of the enzyme solution in the same buffer for 2 h at room temperature The resulting reactor was washed for 3 h with 0.1 M glycine buffer of pH 7.5, and was stored in the 0.1 M phosphate buffer at 5°C when not in use. The reactor was positioned between the injector and a Yanagimoto flow-through Pt electrode in the flow injection system described previously (Anal. Chim. Acta, 1990, 231, 121) for the determination of L-glutamate with use of 1 mM L-alanine in 0.1 M phosphate buffer (pH 7.2) as carrier solution and an applied potential of 0.5 V vs. Ag - AgCl. The reaction principle is described. At the optimum reactor temperature of 37°C and a flow rate of 0.3 mL min-1, the amplification factor was 24; the detection limit was 0.1 µM and the calibration graph was curvilinear. The method could also be used to determine 2-oxoglutarate.
l-Glutamate Amperometry Electrode Electrode

"Enzymic Determination Of Ethanol By Flow Injection Analysis Using A Kel-F Wax - Carbon-paste Electrode"
Electroanalysis 1991 Volume 3, Issue 7 Pages 625-630
Julie Wangsa, Neil D. Danielson

Abstract: The electrode was prepared from graphite powder and Kel-F wax in the wt. ratio 1.25:1. The graphite powder was first treated with hexane folowed by CHCl3, acetone and 6 M HNO3 and then dried at 100°C. This pre-treatment improved the reponse of the Kel-F wax - carbon-paste electrode by ~36% and improved electrode-to-electrode reproducibility. The graphite powder was added slowly with stirring to the melted Kel-F. After cooling and further mixing, a small amount of the paste was packed into the flow cell cavity, and the electrode surface was flattened and polished. The freshly prepared electrode was equilibrated for ~8 h by flow injection in the presence of buffer. Generally, the carrier solution used for standards and samples contained 20 iu mL-1 of alcohol dehydrogenase, 1.25 mM NAD+ and 2% (w/v) of polyoxyethylene glycol (to stabilize the enzyme) in 0.05 M Tris - HCl buffer (pH 8.0). Wine samples were diluted by a factor of 200 before analysis. The calibration graph was rectilinear from the detection limit of 0.44 mM to 33 mM.
Ethanol Wine Electrode

"Determination Of Amalgam-forming Metals By Anodic-stripping Voltammetry In Solutions Containing Dissolved Oxygen"
Electroanalysis 1991 Volume 3, Issue 9 Pages 925-928
Miloslav Kopanica, Vera Stara

Abstract: Graphite powder (1 g) was mixed with silica gel (0.1 g) and the blend was further mixed with ceresin wax at 60°C. The warm mixture was pressed into a PTFE cylinder (5 cm x 0.2 mm) to form an electrode. Such electrodes (with Ag - AgCl reference and Pt counter electrodes) were used for linear scan or differential-pulse voltammetry. The solution for anlaysis were prepared to contain 0.1 M acetate buffer (pH 4.5) and 1 mM Hg(NO3)2 (to form the Hg film). After each use, the Hg film was removed mechanically or electrochemically. No O removal was necessary. Rectilinear calibration graphs were obtained for 5 to 150 µM of Cu(II), Pb(II) and Zn(II) with deposition at -1.2 V for 10 s (unstirred). For 10 to 500 nM solution of, e.g., Pb(II), the supporting electrolyte was 0.3 M HCl, the Hg2+ concentration. was 10 µM and deposition was for 3 min at -0.9 V, with stirring. The film was removed at +0.5 V. At 10 to 50 nM, the deposition was increased to 6 min. The method was applied in the determination of Pb in used motor oil (after extraction with 3 M HCl).
Metals Lead Oil Electrode Voltammetry Sample preparation

"Detection Of Hydrogen Peroxide And Other Molecules Of Biological Importance At An Electrocatalytic Surface On A Carbon Fibre Microelectrode"
Electroanalysis 1997 Volume 9, Issue 2 Pages 102-109
Wilbur B. Nowall, Werner G. Kuhr*

Abstract: The electrocatalytic oxidation of hydrogen peroxide in solution at a modified carbon fiber electrode has been investigated. A simple electrochemical procedure has been developed to dramatically improve the voltammetry for the oxidation of peroxide, NADH, and several other species under steady state and fast scan voltammetry. The surface is generated by the electrochemical oxidation of NADH followed by exposure to peroxide. This procedure yields a surface which is sensitive to peroxide and stable in air for more than 90 days. This oxidation occurs at a potential such that it is easily discriminated from the analytes tested in this study. The tapered tip of a 32 µm diameter C fiber electrode was exposed to a stream of H2O-saturated air before and after polishing with 1000-grit sandpaper for 10 s. The tip was subjected to sine wave excitation from 0.1-1.1 V at 50 Hz, 600 mV bias and 38°C in phosphate buffer of pH 7.4 with ten 5 s injections of 100 µM-NADH followed by 1 mM H2O2. The injections were made at 1 min intervals. The electrode was used with phosphate buffer of pH 7.4 as supporting electrolyte and a Ag/AgCl reference electrode. At a scan rate 10 mV/s E1/2 for H2O2 was >1.1 V and there was no interference from NADH, ascorbate, dopamine, 3,4-dihydroxyphenylacetic acid and uric acid (E1/2 = +290, -25, +60, +110 and +225 mV, respectively) which could also be determined at the electrode. The electrode response to these compounds was also studied at 100 V/s at which calibration graphs were linear from the detection limit (1 µM) to 10 mM H2O2. The electrode was stable in air for >90 days and the response time was a few hundred ms. H2O2 may be useful as a diffusive redox mediator for immobilized oxidases. The electrode may also be useful for in situ and FIA applications. 50 References
Hydrogen peroxide Voltammetry Electrode

"Determination Of Ascorbic Acid In Human Urine By High Performance Liquid Chromatography Coupled With Fluorimetry After Post-column Derivatization With Benzamidine"
J. Chromatogr. A 1987 Volume 385, Issue 1 Pages 287-291
Tokuichiro Seki and Yoshihisa Yamaguchi, Kohji Noguchi and Yuzo Yanagihara

Abstract: Urine was mixed with an equal volume of 5% H3PO4 containing 0.5% of thiodiethanol(I) and a portion (1 ml) was filtered through a cooled column (10 cm x 7 mm) of Dowex 50W-X8 (200 to 400 mesh; H+). Elution was carried out with 2 mM tartaric acid containing 0.05% of I, the eluate was filtered (0.45 µm), and a portion (50 to 250 µL) was analyzed on two columns (50 cm x 7.6 mm), at 30°C, packed with Asahipak GS-320 and connected in series. The mobile phase (1 mL min-1) was tartaric acid (4.5 g), Na2EDTA (1.5 g) and I (1 g) dissolved in water (2 l) and adjusted to pH 3.00 to 3.03 with 4 M NaOH. Post-column derivatization was achieved at 90°C with 20 mM benzamidine in 0.75 M potassium phosphate (pH 10) followed by fluorimetric detection at 400 nm (excitation at 325 nm). The separation of glucose, dioxogulonic acid plus dioxogluconic acid, dehydroisoascorbic acid, dehydroascorbic acid, ascorbic acid and isoascorbic acid, was achieved in 55 min. The recoveries of ascorbic acid and isoascorbic acid at concentration. of 10 and 50 µM, respectively, were 98.2 ± 1.7% and 98 ± 1.5%. The correction procedures required to compensate for conversion effects on the column are discussed.
Ascorbic acid isoascorbic acid Urine HPLC Fluorescence

"Online Post-column Fluorescence Derivatization Of Arginine-containing Peptides In High Performance Liquid Chromatography"
J. Chromatogr. A 1987 Volume 392, Issue 1 Pages 309-316
Masahiro Ohno, Masaaki Kai and Yosuke Ohkura

Abstract: Sample solution, e.g., a tryptic digest of β-melanocyte-stimulating hormone, were subjected to HPLC on a column (20 cm x 4 mm) of TSKgel ODS-120T (5 µm) with a gradient of acetonitrile in 0.2 M sodium phosphate buffer (pH 2.3) at 1 mL min-1. The column eluate was passed through a UV detector at 215 nm and was then mixed with alkaline benzoin reagent (pumped at 1 mL min-1) in a water bath at 76°C. The solution was adjusted to pH 8 to 10 and fluorescence was measured at 435 nm (excitation at 325 nm). Calibration graphs obtained with both detection methods were rectilinear for 0.1 to 1 nmol injected, with detection limits of 5 to 15 pmol and 10 to 20 pmol for fluorescence and UV detection respectively, but UV detection at 215 nm was much less specific.
Peptides HPLC Fluorescence

"Sensitive Monitoring Of Hexosamines In High Performance Liquid Chromatography By Fluorimetric Post-column Labelling Using The Pentane-2,4-dione - Formaldehyde System"
J. Chromatogr. A 1983 Volume 281, Issue 1 Pages 340-344
Susumu Honda, Tadao Konishi, Shigeo Suzuki, Kazuaki Kakehi, and Shigetake Ganno

Abstract: Glycoconjugates were hydrolyzed with 4 M HCl, the hydrolysate was treated with glycerol - ethanol and the residue after evaporation was dissolved in water.Portions of this solution (~20 nmol of total hexosamine) were analyzed by HPLC at 60°C on a column (25 cm x 4 mm) packed with Hitachi 2617 cation-exchange resin (5.3 µm); elution was effected at 0.3 mL min-1 with Na2B4O7 buffer solution (pH 7.5) and the eluate was mixed with 6% pentane-2,4-dione in acetate buffer solution (pH 4.8) and 9% formaldehyde in the same buffer solution, each flowing at 0.5 mL min-1. The mixed solution passed through a heating coil at 95°C, and the fluorescent products were detected at 476 nm (with excitation at 417 nm). The calibration graph was rectilinear for 0.3 to 70 nmol of glucosamine or galactosamine, and the detection limit was 0.14 or 0.23 nmol, respectively.
Glucosamine Galactosamine Hexosamine HPLC Fluorescence

"Rapid Determination Of Aflatoxin B1 In Dutch Feeding-stuffs By High Performance Liquid Chromatography And Post-column Derivatization"
J. Chromatogr. A 1983 Volume 282, Issue 1 Pages 457-462
L. G. M. Th. Tuinstra and W. Haasnoot

Abstract: Pre-treatment involves extraction with CHCl3 and clean-up by two-directional t.l.c. on silica gel. Extracts are spotted along the middle line of a t.l.c. plate, and development is effected in one direction with ethyl ether, then, after the area of migration has been cut away, in the opposite direction with CHCl3 - acetone (22:3) containing 0.2% of water to cause the aflatoxin to migrate. Acetone - CH2Cl2 (2:3) is used to extract the aflatoxin from the silica gel for subsequent HPLC analysis on Microsphere C18 at 60°C with aqueous 30% acetonitrile as mobile phase. The eluate is mixed with saturated aqueous iodine and, after reaction at 60°C, aflatoxin B1 is determined fluorimetrically at >420 nm (excitation at 360 nm). With the post-column reaction, sensitivity is improved 50-fold, enabling <1 ppb to be detected.
Aflatoxin B1 Feed HPLC Fluorescence

"Application Of High Performance Liquid Chromatography-flow Injection Analysis For The Determination Of Polyphosphoric Acids In Phosphorus Smokes"
J. Chromatogr. A 1984 Volume 290, Issue 4 Pages 163-172
R. S. Brazell, R. W. Holmberg and J. H. Moneyhun

Abstract: Aerosols formed by burning red phosphorus impregnated in butyl rubber, and white phosphorus in felt, are collected on glass-fiber pads and dissolved in NaCl - EDTA solution. Phosphates up to the P13 polymer are separated by HPLC on an Aminex A-27 (8% cross-linked) quaternary ammonium anion-exchange column (30 cm x 4 mm) with aqueous NaCl (pH 10) in gradient elution; polyphosphates up to P18 are separated on an Aminex A-14 (4% cross-linked) column. Detection is achieved by flow injection analysis at 140°C, with use of ascorbic acid - molybdate solution to hydrolyse polyphosphates and react with the orthophosphate formed, with detection at the convenient but non-optimum wavelength of 660 nm. Significant changes in composition occur with aerosol ageing, due to hydrolysis and depolymerization. Free-burning phosphorus samples are found to give straight-chain species of less than P11 only.
Phosphate Polyphosphates Smoke Smoke HPLC Spectrophotometry

"Electrochemical Detection Of Reducing Carbohydrates In High Performance Liquid Chromatography After Post-column Derivatization With 2-cyanoacetamide"
J. Chromatogr. A 1984 Volume 299, Issue 1 Pages 245-251
Susumu Honda, Tadao Konishi and Shigeo Suzuki

Abstract: The carbohydrates were separated by HPLC in the gel-permeation, ion-exchange or partition mode. Column eluates were mixed with 0.2 M borate buffer, pH 9.5, and aqueous 1.5% 2-cyanoacetamide in the ratio 2:1:1, and the mixture was passed through a reaction coil at 100°C. The reaction mixture was cooled and products were detected at a vitreous-carbon electrode at +0.4 V vs. silver - AgCl. The method was suitable for determination of, e.g., 50 pmol to 2 nmol of glucose (detection limit 20 pmol), with similar results for other reducing carbohydrates. Alditols, aldonic acids, aldaric acids and non-reducing oligosaccharides did not react and ketoses and N-acetylneuraminic acid reacted only weakly.
Carbohydrates HPLC Electrode

"Enantiomeric Separation Of Underivatized α-methyl-α-amino-acids By High Performance Liquid Chromatography"
J. Chromatogr. A 1985 Volume 318, Issue 1 Pages 117-121
Shulamith Weinstein and Nelu Grinberg

Abstract: α-Methyl-α-amino-acid enantiomers are separated on a column (24 cm x 4.6 mm) packed with Nucleosil C18 and previously equilibrated with an aqueous solution of 0.32 M NN-dimethyl-L-valine or 0.32 M NN-dipropyl-L-alanine containing 0.16 M Cu(II) acetate; addition of 0.1 M Na acetate to bring the pH to 7 is advantageous. Post-column derivatization with phthalaldehyde is effected with use of a 10-m PTFE loop immersed in a water bath at 50°C and detection is by fluorimetry at 425 nm (excitation at 340 nm).
Amino acids, α methyl HPLC Fluorescence

"Post-column Reaction Of Amino-acids With The Pentane-2,4-dione - Formaldehyde System For Their Automated Analysis"
J. Chromatogr. A 1985 Volume 318, Issue 2 Pages 367-372
Kazuaki Kakehi, Tadao Konishi, Ikuo Sugimoto and Susumu Honda

Abstract: The amino-acid sample is separated on a glass column (40 cm x 9 mm) packed with Hitachi 2611 resin with gradient elution from 0.2 M citrate buffer (pH 3.25) to 1.2 M citrate buffer (pH 5.28) at a flow rate of 1.0 mL min-1. The eluate is treated with 6% pentane-2,4-dione solution and 9% formaldehyde solution, both in 1 M acetate buffer (pH 6.22) in a PTFE coil (30 m x 0.5 mm) at 95°C, and the fluorescent reaction products are detected at 476 nm (excitation at 417 nm). The detection limits for glycine(I) and lysine(II) are 342 and 267 pmol, respectively; calibration graphs are rectilinear for 5 to 500 nmol of serine, I or II, and the coefficient of variation (at 50 nmol) are <5%. The method was applied to a nutritional drink, chymotrypsinogen and insulin acid hydrolysates and normal human urine.
Amino Acids Glycine Lysine Nutritional Urine HPIC Fluorescence

"Simultaneous Determination Of Phosphate And Phosphonates By Flow Injection Analysis And High Performance Liquid Chromatography With A Series Detection System"
J. Chromatogr. A 1985 Volume 318, Issue 2 Pages 319-324
Yoshinobu Baba, Norimasa Yoza and Shigeru Ohashi

Abstract: The sample solution (200 µL) was introduced into a stream of water (1.0 mL min-1) and mixed with a MoV - Mo(VI) reagent stream (0.5 mL min-1). The mixture was passed through a 10-m reaction coil at 140°C (in which polyphosphate was hydrolyzed to orthophosphate) and the heteropoly-blue complex formed between P(V) and Mo reagent was detected at 830 nm. The detector effluent was mixed with a stream of 1 M SO32- (0.2 mL min-1), and the P(III) was oxidized to P(V) and complexed with Mo reagent in a second reaction coil before detection of total P at 830 nm. For an equimolar P(V) - P(III) mixture the calibration graphs were rectilinear for 10 to 50 µM with coefficient of variation of 1.1 to 1.3%. Various oxo-acids of P were separated and identified by HPLC coupled to the flow injection analysis method described. (Cf. Anal. Abstr., 1985, 47, 3B86).
Phosphate Phosphonates HPLC Spectrophotometry

"High-speed Liquid Chromatographic Analysis Of Amino-acids By Post-column Sodium Hypochlorite - Phthalaldehyde Reaction"
J. Chromatogr. A 1985 Volume 327, Issue 1 Pages 17-25
Michael W. Dong and J. Russel Gant

Abstract: The 16 standard hydrolysate amino-acids have been separated within 30 min on a column (12 cm x 4.6 mm) packed with sulfonated cation-exchange resin (6 µm) maintained at 60°C. Several commercial buffers can be used for step-gradient elution and results with use of Buffelute (Pierce) are presented. Post-column derivatization is effected at 40°C with use of phthalaldehyde added to 2-mercaptoethanol and aqueous 30% Brij-35. The NaClO reagent is prepared in a borate buffer solution (pH 10.4). Down to 10 to 100 pmol can be determined, while the calibration graphs are rectilinear for 10 nmol. With a small loss of resolution, a 22-min analyis is possible. Results for a soya-protein hydrolysate show excellent correlation (r >0.999) with those obtained by a method with post-column ninhydrin derivatization.
Amino Acids HPLC Spectrophotometry

"Determination Of Anthraquinones In Pulping Materials By High Performance Liquid Chromatography Using Online Post-column Derivatization"
J. Chromatogr. A 1985 Volume 328, Issue 1 Pages 309-315
Nobutoshi Kiba, Motoharu Takamatsu and Motohisa Furusawa

Abstract: A selective assay for anthraquinones in black liquors and paper, based on their reduction by Na2S2O4 to anthraquinols, was developed. The anthraquinones were extracted with cyclohexane (from liquors) or CH2Cl2 (from paper) and portions of the extract were analyzed on a column (25 cm x 4.6 mm) packed with Jasco Finepak SIL C18 (10 µm), with acetonitrile - 0.3 mM HCl (7:3) as mobile phase (0.75 mL min-1) and mixing of the eluate with 0.2 M S2O42- in 0.5 M NaOH (at 0.5 mL min-1) and water (at 0.25 mL min-1), followed by passage of the mixture through a PTFE tube (100 cm x 0.5 mm) at 30°C and measurement of the absorbance at 500 nm. The method is applicable for 0.3 to 80 nmol of anthraquinones in 50 µL of injected sample. Mixtures of anthraquinone and four of its derivatives at ppm levels were analyzed by the proposed method, which is less sensitive than conventional HPLC methods.
Anthraquinone Commercial product Pulp HPLC Spectrophotometry

"Separation Of Ascorbic Acid, Dehydroascorbic Acid, Dioxogulonic Acid And Glucose By Isocratic Elution From A Column Of A Hydrophilic Gel"
J. Chromatogr. A 1985 Volume 332, Issue 1 Pages 283-286
Tokuichiro Seki, Yoshihisa Yamaguchi, Kohji Noguchi and Yuzo Yanagihara

Abstract: Orange juice was applied to a mixed-bed ion-exchange column (10 cm x 6 mm) of Amberlite CG-50 and Amberlite XAD-2 with elution with aqueous 15 mM tartrate buffer (pH 3) containing 2 mM EDTA and 0.05% of 2,2'-thiodiethanol. The eluate was analyzed by HPLC on a column (50 cm x 7.6 mm) of Asahipak GS-320 at 30°C with the above mobile phase, and the eluate was subjected to post-column derivatization, at 90°C, with a 1:1 mixture of 0.02 M benzamidine hydrochloride and 0.25 M potassium borate buffer (pH 10) containing 0.25 M K2SO3 before fluorescence measurement at 400 nm (325-nm excitation). Separation of glucose, dioxogulonic acid, dehydroascorbic acid and ascorbic acid was achieved; the calibration graph was rectilinear for 5 to 500 ng of ascorbic acid.
Ascorbic acid dehydroascorbic acid Diketogulonic acid Glucose Juice HPLC Fluorescence

"Estimation Of Catecholamines By Ion-exchange Chromatography On Asahipak ES-502C Using Glycylglycine As The Post-derivatization Agent"
J. Chromatogr. A 1985 Volume 332, Issue 1 Pages 9-13
Tokuichiro Seki, Yoshihisa Yamaguchi, Kohji Noguchi and Yuzo Yanagihara

Abstract: Urine was treated with aqueous 5% EDTA, aqueous 1% ascorbic acid and 0.01 M HCl containing isoprenaline (internal standard). The pH was adjusted to 6.2 to 6.3, the solution was applied to a column of Amberlite CG-50, and the catecholamines were eluted with 0.66 M H3BO3. The eluate was mixed with 0.08 M succinic acid containing EDTA and 2,2'-thiodiethanol, and subjected to chromatography on a column (10 cm x 7.6 mm) of Asahipak ES-502C, at 60°C, with 0.05 M succinate - 0.015 M borate - 0.5 mM EDTA (pH 5.25) as the mobile phase (1 mL min-1), with post-column derivatization of the eluate by heating at 90°C with 0.1 M glycylglycine containing 0.05 M H3BO3, 3 mM ZnSO4, 0.2 M tartaric acid and 0.25 M potassium borate buffer (pH 9.2) containing 0.01% of Fe(CN)63-. Determination was by measurement of the fluorescence. Good separation of adrenaline(I), noradrenaline(II) and dopamine(III) was achieved and the calibration graphs were rectilinear for 0.5 to 100 ng of I and II, and 1.5 to 150 ng of III. Reproducibility was good and recoveries were 96%.
Catecholamines Adrenaline Noradrenaline Dopamine Urine HPIC Fluorescence

"Effect Of Column Temperature On High Performance Liquid Chromatographic Behaviour Of Inorganic Polyphosphates. 1. Isocratic Ion-exchange Chromatography"
J. Chromatogr. A 1985 Volume 348, Issue 1 Pages 27-37
Yoshinobu Baba, Norimasa Yoza and Shigeru Ohashi

Abstract: Sample solution (100 µL) were analyzed by HPLC on a column (25 cm x 4 mm) packed with TSK gel SAX (10 µm) with a mobile phase (1.0 mL min-1) of KCl solution that contained 0.1% of Na4EDTA (pH 10). The column eluate was mixed in a reaction coil (20 m x 0.5 mm; 140°C) of a flow injection analysis system with streams of MoV - Mo(VI) reagent (0.8 mL min-1) and water (0.2 mL min-1) and the absorbance of the subsequent heteropoly blue complex was monitored at 830 nm in a flow-through cell. The capacity factor was measured as a function of mobile phase concentration, and the effect of column temperature on the retention and resolution of inorganic polyphosphates was investigated. The optimal elution conditions as a function of column temperature and mobile phase concentration. at pH 10 were determined by using a computer-assisted retention-prediction system (cf. Baba, Kaiho - Kagaku PC Kenkyukai, 1985, 7, 119).
Polyphosphates HPLC Spectrophotometry

"Determination Of Biogenic Amines In Cheese And Some Other Food Products By High Performance Liquid Chromatography In Combination With Thermo-sensitized Reaction Detection"
J. Chromatogr. A 1986 Volume 356, Issue 2 Pages 311-319
H. M. L. J. Joosten and C. Olieman

Abstract: Biogenic amines were extracted from cheese, chocolate, fish, wine and sauerkraut by precipitation with trichloroacetic acid before HPLC on a radial-compression cartridge (10 cm x 8 mm) packed with Nucleosil C18 and equipped with a pre-column of Corasil C18. The mobile phase was aqueous 47% dimethyl sulfoxide containing 1 g L-1 of Na dodecyl sulfate and 2.8 M in Na acetate buffer (pH 5); ninhydrin (8 g l-1) and hydrindantin (0.6 g l-1) were dissolved in the mobile phase to effect post-column derivatization of the amines without need for an extra reagent pump. Detection was by using a PTFE knitted-tube reactor at 145°C and measuring the absorbance at 546 nm. Recovery of amines from cheese was 85 to 105%. The detection limit was 2 mg kg-1 in cheese and the response was rectilinear for 0.1 to 4 µg of amine injected. Detection limits for amines in sauerkraut and wine were 0.8 and 0.3 mg kg-1, respectively.
Amines, biogenic Food Food Marine Food Wine HPLC Spectrophotometry

"Separation Of Collagen Hydrolysate Amino-acids By Ion-pair Reversed-phase High Performance Liquid Chromatography"
J. Chromatogr. A 1986 Volume 364, Issue 1 Pages 253-257
J. Macek, L. Miterov&aacute; and M. Adam

Abstract: Protein (~1 mg) was hydrolyzed in 1 mL of 6 M HCl at 110°C for 16 h under N. The hydrolysate was evaporated to dryness, the residue was dissolved in 1 mL of water, and 100 µL aliquots were injected on to a stainless-steel column (25 cm x 4.6 mm) of Ultrasphere IP (5 µm) with gradient elution at 1.2 mL min-1 with aqueous Na dodecyl sulfate - 1 M trichloroacetic acid of pH 3.0 and pH 2.1 and 0.3% Na dodecyl sulfate in 80% aqueous propan-2-ol; the gradient program is given. Post-column derivatization with ninhydrin at 140°C was followed by detection at 440 nm (then 570 nm after elution of aspartic and glutamic acids). Separations of the amino-acids were achieved within 45 min. For individual compounds the detection limits were in the range 50 pmol to 1 nmol. The reproducibility was <4.5% for all amino-acids except methionine (8.1%) and cystine (9.2%).
Amino acids, collagen hydrolysates HPLC Spectrophotometry

"Fluorimetric Determination Of Amino-acids By High Performance Liquid Chromatography Using A Hollow-fiber Membrane Reactor"
J. Chromatogr. A 1987 Volume 396, Issue 1 Pages 297-305
Jun Haginaka and Junko Wakai

Abstract: Primary amino-acids were separated on a column (15 cm x 4.6 mm) packed with Develosil ODS-5 (5 µm), with Na heptanesulfonate(I) as ion-pairing agent. Post-column derivatization was performed in two sulfonated hollow-fiber membrane reactors (30 cm and 1 m) in series. The mobile phase was 15 mM I - 27 mM H3PO4 - 3 mM NaH2PO4 - methanol (40:40:40:3 or 2:2:2:3) at 0.8 mL min-1. The first reactor (30 cm) was immersed in 0.2 M Na2B4O7 - 0.6 M NaOH, and the second in 0.6% phthalaldehyde - 1.0% 2-mercaptoethanol solution (derivatizing agents), both at 60°C. Fluorimetric detection was at 450 nm (excitation at 340 nm). A better or similar sensitivity was obtained compared with conventional post-column derivatization in an open-tubular reactor, which also required an additional pump, mixing T-piece and reactor. The detection limits were 0.2 to 2.3 pmol at a signal-to-noise ratio of 3. The coefficient of variation was ~1.1 to 4.0% (n = 20) for 48 to 110 pmol.
Amino Acids HPLC Fluorescence

"Post-column Derivatization System For The Fluorimetric Determination Of Guanidino-compounds With Ninhydrin By Reversed-phase Ion-pair High Performance Liquid Chromatography"
J. Chromatogr. A 1987 Volume 400, Issue 1 Pages 113-121
Yoshie Kobayashi, Hiroaki Kubo and Toshio Kinoshita

Abstract: Serum was mixed with 20% trichloroacetic acid and centrifuged. The supernatant solution was mixed with 0.4 M NaOH and adjusted to pH 2.5 to 3.0. The solution was subjected to HPLC on a column (15 cm x 4.6 mm) of Nucleosil C8 (5 µm) with a mobile phase of 15 mM Na octanesulfonate and 5 mM ninhydrin in water - acetonitrile - methanol (92:3:5; pH 3.5 or 4.0) with post-column derivatization at 75°C, and detection at 500 nm (excitation at 395 nm). Recoveries were 96.1 to 107.0% and the within-run coefficient of variation were 1.59 to 3.00%.
Guanidino compounds Blood Serum HPIC Fluorescence

"Application Of Bis-[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl] Oxalate To Post-column Chemiluminescence Detection In High Performance Liquid Chromatography"
J. Chromatogr. A 1987 Volume 400, Issue 1 Pages 169-176
Kazuhiro Imai, Yoriko Matsunaga, Yukie Tsukamoto and Atsuhiko Nishitani

Abstract: The sample was subjected to HPLC, at 30°C, on a column (15 cm x 4.6 mm) of TSK LS 120-T with a mobile phase (0.6 mL min-1) of 0.1 M imidazole nitrate (pH 7.0) - acetonitrile (7:3) and post-column derivatization with 0.05 mM bis-[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl] oxalate - 5 mM H2O2 in acetonitrile - ethyl acetate (1:1) and chemiluminescence detection. The method was applied in the determination of dansylated amino-acids.
Amino acids, dansylated Chemiluminescence HPLC

"Determination Of Photosynthetic Intermediates In Leaves By High Performance Liquid Chromatography"
J. Chromatogr. A 1987 Volume 402, Issue 1 Pages 283-292
Shinichi Sawada*, Minobu Kasai, Tsuyoshi Yamada and Toyohiko Takahashi

Abstract: Sugar phosphates and nucleotides in extracts from leaves kept under photosynthetic conditions were separated on a column (25 cm x 6 mm, plus 1.5-cm pre-column) of strongly basic anion-exchange resin (Shodex TML, 15 to 20 µm) with programmed gradient elution by 0.6 M H3BO3 - 0.8 M NaH2PO4 buffer (pH ~4) during 3 h. The compounds in the eluate were subjected to reaction with 0.1% orcinol in 70% H2SO4 in a tube (47 m x 0.5 mm) heated in an oil bath at 130°C, followed by UV irradiation and detection of carbohydrates at 420 nm and of nucleotides at 260 nm. The method was applied particularly to samples from soya-bean leaves.
Nucleotides Sugars, phosphate Leaves HPLC Spectrophotometry

"High Performance Liquid Chromatographic Method For Determining Trichothecene Mycotoxins By Post-column Fluorescence Derivatization"
J. Chromatogr. A 1987 Volume 410, Issue 2 Pages 427-436
Akira Sano, Satoshi Matsutani, Masao Suzuki and Shoji Takitani

Abstract: The procedure used for the extraction and cleanup of the mycotoxins from cereal samples was essentially that of Tanaka et al. (Food Addit. Contam., 1985, 2, 125), except that a Sep-Pak CN cartridge rather than a Sep-Pak silica cartridge was used in the final stage. HPLC was carried out on a column (25 cm x 4 mm) packed with LiChrosorb RP-18 (10 µm), preceded by a guard column (LiChroCART RP-18), with a mobile phase (1 mL min-1) of aqueous 15% acetonitrile. The eluate was mixed first with 0.15 M NaOH (0.5 mL min-1) for passage through a PTFE reaction coil (8 m x 0.5 mm) at 115°C, and then with 30 mM methyl acetoacetate - 2 M ammonium acetate (0.5 mL min-1) for passage through a second PTFE reaction coil (6 m x 0.5 mm) at 115°C. After cooling, the fluorescence was monitored at 460 nm (excitation at 370 nm). The calibration graphs for deoxynivalenol, nivalenol and fusarenone were rectilinear with corresponding detection limits of 5, 5 and 10 ng; coefficient of variation were 0.6 to 5.4%. The recoveries of 0.05 to 1 ppm of deoxynivalenol and nivalenol added to cereals were 79.6 to 96.9 and 61.4 to 90.6%, respectively.
Deoxynivalenol Nivalenol Grain HPLC Fluorescence

"High Performance Liquid Chromatographic Analysis Of Arginine-containing Peptides In Biological Fluids By Means Of A Selective Post-column Reaction With Fluorescence Detection"
J. Chromatogr. A 1988 Volume 444, Issue 1 Pages 123-131
Gerald R. Rhodes and Venkata K. Boppaa

Abstract: Plasma (1 ml) containing SKF 104146 (1 µg mL-1) as internal standard was cleaned up on a 1 mL cation-exchange solid-phase extraction cartridge. The cartridge was washed with water (1 ml), and the washings were applied to the cartridge which was then washed with aqueous 1% trifluoroacetic acid (I; 1 ml), water (2 ml) and methanol (2 ml). The peptide was eluted with methanolic 2% I (2 ml). Following evaporation of the solvent, the residue was dissolved in chloroacetate buffer of pH 3.2 (prep. described) - methanol (1:1; 0.1 ml), and the solution was analyzed by HPLC on a column (25 cm x 2 mm) of Ultrasphere C8 (5 µm), at 60°C, with a mobile phase (0.3 mL min-1) of chloroacetate buffer - methanol. For some samples, Na octanesulfonate was used as ion-pair reagent. The eluate was mixed with ninhydrin and NaOH, and the product was determined fluorimetrically at 470 nm (excitation at 390 nm). The range of application of the method was 0.5 to 100 nM; the detection limit was 50 fmol.
Peptides, arginine containing Blood Plasma HPLC Fluorescence

"Determination Of Salsolinol By Ion-exchange Chromatography With Glycylglycine As The Post-derivatizing Agent"
J. Chromatogr. A 1988 Volume 459, Issue 1 Pages 245-249
Tokuichiro Seki, Yuzo Yanagihara and Kohji Noguchi

Abstract: Filtered urine (10 ml) was mixed with a 2% solution of semicarbazide hydrochloride containing 0.5% each of Na2S2O5 and Na2EDTA. The mixture was adjusted to pH 6.3 to 6.4 with 0.5 M NaHCO3 and applied to a column of Amberlite CG-50 buffered at pH 6.5. Salsolinol(I) was eluted with 2 to 3 M H3BO3 into a mixture of 0.1 M succinic acid and 0.1 M EDTA containing 5% of 2,2'-thiodiethanol, before separation from adrenaline, noradrenaline and dopamine on a column (10 cm x 7.6 mm) of Asahipak ES-502C at 35°C, with 0.05 M succinate - 0.015 M borate - 0.5 mM EDTA (pH 5.5) as mobile phase (1.5 mL min-1). The I fraction was then switched to a second Asahipak column maintained at 60°C, and, after elution with the cited mobile phase, I was determined fluorimetrically at >420 nm (excitation at 365 nm) after derivatization at 65°C with glycylglycine in the presence of Fe(CN)64- at pH 7.5 8. The detection limit was 2 nM.
Salsolinol Urine HPIC Fluorescence

"High Performance Liquid Chromatography - Time-of-flight Mass Spectrometry And Its Application To Peptide Analyses"
J. Chromatogr. A 1991 Volume 536, Issue 1-2 Pages 143-153
Richard C. Simpson, W. Bart Emary, Ihor Lys and Robert J. Cotter, Catherine C. Fenselau

Abstract: A continuous-flow probe described by Chen and Cotter (Anal. Abstr., 1989, 51, 5J115) was modified, employing a metal solder seal around the fused-silica capillary at the outlet tip (maintained at 40°C to 60°C) to provide better electrical and thermal conductivity. The probe was used as an interface to couple the HPLC column (20 cm x 0.2 mm) with a mobile phase (1 µL min-1) of 28% acetonitrile - glycerol - trifluoroacetic acid (89.9:10:0.1) to a time-of-flight mass spectrometer. Chromatograms and mass spectra are presented for the analysis of peptides.
Peptides HPLC Mass spectrometry

"Optimized High Performance Liquid Chromatographic Procedure For The Separation And Quantification Of The Main Folacins And Some Derivatives. I. Chromatographic System"
J. Chromatogr. A 1991 Volume 540, Issue 1-2 Pages 207-215
A. Hahn, J. Stein, U. Rump and G. Rehner

Abstract: Folates (folacins) were separated and determined by HPLC in a column (25 cm x 4.6 mm) of Hypersil ODS (3 µm) with use of a C-135B pre-column (Upchurch Scientific, Oak Harbour, WA, USA) containing Hypersil ODS (10 µm), a gradient mobile phase (0.9 mL minmin1) of aqueous 5 mM KH2PO4 (pH 2.3) - acetonitrile (93:7 to 87:13 over 15 min, then to 81:19 in 3 min and to 79:21 in 3 min) and detection at 295 nm or by fluorimetry at 356 nm (excitation at 295 nm) or for post-column derivatives at 450 nm (excitation at 365 nm). Post-column derivatization to pterins was with 1% H2S2O8 in a PTFE coil (10 m x 0.8 mm) at 60°C. Lower detection limits for folates were from 1.1 to 2.7 (295 nm) or 0.007 to 0.89 ng injected (356-nm fluorimetry). Methotrexate and 3',5'-dichlorofolic acid were used as internal standards.
Folacins HPLC Fluorescence

"Determination Of Non-ionic Surfactants With Ester Groups By High Performance Liquid Chromatography With Post-column Derivatization"
J. Chromatogr. A 1991 Volume 541, Issue 1-2 Pages 431-441
Yukihiro Kondoh, Akio Yamada and Satoshi Takano

Abstract: Non-ionic sorbitan or sucrose fatty-acid mono- to penta-ester surfactants (10 to 500 µg injection) were separated by HPLC on a stainless steel column (15 cm x 4.6 mm) of Hitachi gel 3057 at 50°C with a gradient mobile phase (0.8 mL min-1) of 5.7 mM triethylamine in aqueous 85% methanol - ethanolic 25% methanol (details given). Serial post-column reaction coils were used for hydrolysis with 0.45 M KOH in aqueous 50% ethanol at 120°; the liberated acid was derivatized with 2-nitrophenylhydrazine in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodi-imide and pyridine at 70°C before treatment with aqueous NaOH at 100°C and detection at 550 nm. Results for seven sucrose-derived surfactants agreed well with available data.
Surfactants, non ionic HPLC

"Electrochemical Detection Of Oligopeptides Through The Pre-column Formation Of Biuret Complexes"
J. Chromatogr. A 1991 Volume 542, Issue 2 Pages 345-350
Hweiyan Tsai and Stephen G. Weber

Abstract: The post-column reaction for the formation of electroactive Cu(II) - peptide complexes from larger (>6 amino-acids) peptides requires relatively high temperature and a long reaction time. As an alternative, the incubation of three larger peptides (bradykinin, Tyr8-bradykinin and insulin A chain) with biuret reagent for 20 min at 60°C yields complexes which can be analyzed by flow injection analysis or LC using acidic or basic mobile phases and electrochemical detection. The sensitivity of the latter is around 1.0 nC pmol-1 at 0.80 V and a flow rate of 1 mL min-1. The influence of the column packing material on the electrochemical detector response of the Cu - peptide complexes is also considered.
Oligopeptides LC Electrochemical analysis

"Progress In Optimization Of Transition Metal Cation Chromatography And Its Application To Analysis Of Silicon Wafer Contamination"
J. Chromatogr. A 1991 Volume 546, Issue 1 Pages 243-249
Kenneth A. Ruth and Roger W. Shaw

Abstract: A PTFE extraction cell filled with 18.9 mM HF - 50 mM HCl - 4.9 mM H2O2 was subjected to ultrasonication and 11 mL samples were taken for background data. The silicon wafer is added, the cell is filled up with the above mixture and subjected to ultrasonic agitation for ~15 min. Two samples were taken and pre-concentrated on a Dionex TCC-1 trace cation concentrator. Separation was carried out on a Dionex HPIC-CS5 column with 3 mM pyridine-2,5-dicarboxylic acid - 4.3 mM LiOH - 2 mM Na2SO4 - 25 mM NaCl as eluent (1 mL min-1), 1 mM 4-(2-pyridylazo)resorcinol - aqueous 3 M NH3 (pH 11) as post-column derivatization reagent and detection at 520 nm. The second method described is a modification of that of Cassidy and Elchuck (Anal. Chem., 1982, 54, 1558). A PTPE tube held at 60°C was inserted after the addition of post-column reagents. Detection limits were 0.02 to 0.3 ppb by the first method and 0.05 to 0.2 ppm by the second method.
Silicon Chromatography

"Determination Of Polyphosphates In Intermediate Materials For Detergent Manufacture By Ion High Performance Liquid Chromatography With Post-column Derivatization"
J. Chromatogr. A 1991 Volume 585, Issue 2 Pages 267-271
P. Linares, M. D. Luque de Castro* and M. Valc&aacute;rcel

Abstract: Intermediate material was dissolved in 0.1 M KCl and portions of the solution were analyzed with a flow injection system by injection into a stream of 0.1 or 0.2 M KCl (pH 9) containing 1 mM Na4EDTA. The stream was directed to a pre-column of Ion-Guard GA-100 and then to a column (12 cm x 4.6 mm) of Ion-120. The eluate was hydrolyzed with a stream of 3 M H2SO4 after which the stream was heated at 90°C. For derivatization of PO43- and pyro-, tripoly- and trimeta-phosphate, an online stream of 2% ascorbic acid and 5% Na2MoO4 in 3 M NaOH was merged with the sample stream. The derivatives were detected at 820 nm.
Polyphosphates Commercial product HPIC LC Spectrophotometry

"High Performance Liquid Chromatographic Determination Of Monohydroxy-compounds By A Combination Of Pre-column Derivatization And Post-column Reaction Detection"
J. Chromatogr. A 1992 Volume 593, Issue 1-2 Pages 29-36
Venkata K. Boppana*, Richard C. Simpson, Kathleen Anderson, Cynthia Miller-Stein, Timothy J. A. Blake, Bruce Y. H. Hwang and Gerald R. Rhodes

Abstract: Oxiracetam (I) was determined in plasma after derivatization with propyl isocyanate in pyridine at 50°C for 1 h to form the corresponding propyl carbamate ester. The solvent was evaporated to dryness, the residue was dissolved in solvent A [0.05 M acetate buffer (pH 6) - methanol (9:1)] and the solution was analyzed by HPLC. A column (25 cm x 2 mm) of Ultrasphere ODS (5 µm) was used with gradient elution with solvent A (9:1 for 5 min, to 4:1 over 4 min, held for 1 min, then to 1:1 in 1 min, held for 5 min). Post-column derivatization of the ester was carried out at 90°C with methanolic phthalaldehyde solution (2 mg mL-1) and 3-mercaptopropionic acid. The resulting fluorescence was detected at 455 nm (excitation at 340 nm). The calibration graph was rectilinear for 2 to 2000 ng of I with coefficient of variation of 3% (n = 6). The limit of detection was 0.5 ng of I.
Oxiracetam Blood Plasma HPLC Fluorescence

"Post-column Derivatization Of Carbohydrates With Ethanolamine - Boric Acid Prior To Their Detection By High Performance Liquid Chromatography"
J. Chromatogr. A 1992 Volume 607, Issue 2 Pages 191-198
M. J. Del Nozal*, J. L. Bernal, F. J. Gomez, A. Antolin and L. Toribio

Abstract: Concentrated wine samples were subjected to HPLC on a column (50 cm x 3 mm) of Aminex A-25, operated at 69°C, with a mobile phase (1 mL min-1) of 0.4 M borate buffer (pH 9.35). The eluate was hydrolyzed by mixing with aqueous 1.6 M p-toluenesulfonic acid and the mixture was passed through a PTFE tube (10 m x 0.3 mm) at 140°C before merging with the fluorogenic reagent (an aqueous solution containing 20% ethanolamine and 20% H3BO3). The mixture was passed through a PTFE capillary (30 m x 0.3 mm) which was immersed in a reaction bath filled with glycerine at 140°C and then in a water bath at 20°C to cool the mixture. The fluorescence of the cooled mixture was measured at 445 nm (excitation at 400 nm). Melibiose was used as internal standard. Detection limits and calibration ranges for 11 carbohydrates are tabulated.
Carbohydrates Wine HPLC Fluorescence

"Determination Of N-methylcarbamates And N-methylcarbamoyloximes In Water By High Performance Liquid Chromatography With The Use Of Fluorescence Detection And A Single O-phthalaldehyde Post-column Reaction"
J. Chromatogr. A 1993 Volume 643, Issue 1-2 Pages 317-320
Verne A. Simon, Karl S. Pearson and Anne Taylor

Abstract: Water was filtered and injected directly on to a column (15 cm x 4.6 mm) of HS-C18 (3 µm), equipped with a guard column of C18 bonded-phase. Gradient elution (1 ml/min) was effected with aqueous acetonitrile from 5-20% in 13 min, followed by 65% for 15 min and 5% for 2 min (held until the next injection). Fluorescence detection was carried out at 460 nm (excitation at 340 nm). Single-stage post-column derivatization was performed by merging the eluate with a filtered and degassed solution containing o-phthalaldehyde and Thiofluor in 0.05 M NaOH at 0.1 ml/min. The reaction was carried out at 95°C in a 500 µL reaction coil. The reagent was stable for up to 30 injections and led to a faster, simpler operational procedure than the traditional two-stage method without any loss in sensitivity. Detection limits ranged from 0.5-1.2 µg/l, recoveries ranged from 99.4-102% and the RSD (n = 7) ranged from 1.8-3.1%. The calibration graph was rectilinear over the concentration. ranged tested. No interference or other difficulties were encountered with this method.
Carbamates, N-methyl Carbamoyloximes, N-methyl Water HPLC Fluorescence

"High Performance Liquid Chromatographic Method For The Analysis Of Aminocarb, Mexacarbate And Some Of Their N-methylcarbamate Metabolites By Post-column Derivatization With Fluorescence Detection"
J. Chromatogr. A 1994 Volume 672, Issue 1-2 Pages 117-124
K. M. S. Sundaram* and J. Curry

Abstract: Water and soil were extracted with CH2Cl2 and ethyl acetate, respectively, the extracts were dried with Na2SO4, flash evaporated at 30°C, the residue was dissolved in acetonitrile and partitioned twice with hexane. The polar layer was flash evaporated, dissolved in ethyl acetate, concentrated under N2 and cleaned up on alumina with elution by ethyl acetate containing 0 and 10% methanol. After evaporation to dryness, the residue was dissolved in acetonitrile for analysis by HPLC on a column (20 cm x 4.6 mm i.d.) of HP RP-8 OS (10 µm) at 30°C with a guard column (3 cm x 4.6 mm i.d.) of HP RP-8 (10 µm), a gradient mobile phase (1 ml/min) of aqueous 0-30% acetonitrile over 25 min, then to 50% (held for 10 min) over 10 min, post-column derivatization by hydrolysis with 50 mM NaOH in a 1 mL reaction coil at 95°C, reaction with o-phthalaldehyde/2-mercaptoethanol in a 0.5 mL reaction coil at 40°C and fluorimetric detection at 418 nm (excitation at 230 nm). Calibration graphs were linear for 0.1 (detection limit) to 500 ng of aminocarb, mexacarbate and four carbamate metabolites; recoveries from water (2 and 20 ng/ml) and soil (20 and 200 ppb) were 72±7.9% to 98.4±5.2% with RSD of 5-11.5%.
Aminocarb Mexacarbate Carbamates, N-methyl Environmental Environmental HPLC Fluorescence

"Determination Of Amino-acids By Ion-pair Liquid Chromatography With Post-column Derivatization Using 1,2-naphthoquinone-4-sulfonate"
J. Chromatogr. A 1994 Volume 676, Issue 2 Pages 311-319
J. Saurina and S. Hern&aacute;ndez-Cassou*

Abstract: Amino-acids were analyzed by ion-pair HPLC on a column (15 cm x 4.6 mm) of Spherisorb ODS-2 (5 µm) with gradient elution (0.8 ml/min) of 20 mM phosphoric acid/20 mM sodium dihydrogen phosphate/15 mM SDS as eluent A and (25 mM phosphoric acid/25 mM sodium dihydrogen phosphate - 18.5 mM SDS)/propan-2-ol (4:1) as eluent B; 0% B (held for 10 min) to 100% B over 75 min to 0% B (held for 2 min) over 3 min. The column outlet was coupled online to a two channel derivatization system. The reagents 1,2-naphthoquinone-4-sulfonate and 15 mM sodium hydrogen carbonate/0.185 M sodium carbonate were mixed and merged with the column eluate in a reaction coil (4 m x 1.1 mm) at 65°C and spectrophotometric detection at 305 nm. The calibration graph was linear up to 32 nmol for lysine with a detection limit of 0.09 nmol. For the nine amino-acids tested, the repeatability was >4%, reproducibility was >5% and the detection limits were 0.09-0.33 nmol. The method was applied to the determination of amino-acids in animal feed and powdered milks.
Amino Acids Feed Powder HPLC Spectrophotometry

"High Performance Liquid Chromatographic Method For Determination Of Sulfapyridine In Human Saliva Using Post-column, Inline Derivatization With Fluorescamine"
J. Chromatogr. B 1983 Volume 273, Issue 2 Pages 464-468
H. S. Sista, D. M. Dye and J. Leonard

Abstract: A method for determination of sulfapyridine [144-83-2] in human saliva by the title methods is described. To an aliquot of saliva, MeCN, solid K2CO3 and the internal standard, sulfadiazine (148 ng/mL saliva) are added. After mixing and centrifuging the MeCN layer is separated and evaporated to dryness under N at 60°C. The residue is then dissolved in the mobile phase and an aliquot chromatographed. The mobile phase consists of 0.05 M NaHPO4, 0.1 M 1-hexanesulfonate sodium salt, 0.0072 M triethylamine, pH 3.0 (using phosphoric acid), and 15% MeOH. The column was packed with RP-18. The fluorescamine [38183-12-9] solution (stabilized by 2-mercaptoethanol [60-24-2]) was introduced into the mobile phase, post-column, and reacted in an in-line reactor at 60°C. Detection was with a spectrofluorometer with excitation at 395 nm and an emission wavelength of 470 nm. The detection limit for I in saliva is 5 ng/mL.
Sulfapyridine Saliva HPLC Fluorescence

"Determination Of The Antibiotic Fludalanine {3-fluoro-D-[2-2H]alanine} In Plasma And Urine By High Performance Liquid Chromatography Using A Packed-bed, Post-column Reactor With Phthalaldehyde And 2-mercaptoethanol"
J. Chromatogr. B 1985 Volume 338, Issue 1 Pages 357-367
D. G. Musson, S. M. Maglietto and W. F. Bayne

Abstract: Plasma was mixed with 3,3-difluoro-D-alanine(I) as internal standard, and transferred to an ultra-filter and centrifuged; the filtrate was then analyzed. Urine plus I was mixed with acetonitrile and applied to a Sep-Pak silica column and the fraction eluted with water was analyzed. Analysis was by HPLC on a Radial-Pak C18 cartridge (10 cm x 8 mm; 5 µm) with a Guard-Pak C18 cartridge and a mobile phase (2 mL min-1) of Na dodecyl sulfate (50 mg mL-1) in aqueous 10% methanol containing 2 mL L-1 of 85% H3PO4, at pH 2.5. Post-column derivatization was achieved with phthalaldehyde and 2-mercaptoethanol in borate buffer solution in a glass-bead-packed reactor at 40°C with fluorimetric detection at 455 nm (excitation at 340 nm). The calibration graphs were rectilinear for 0.25 to 20 µg mL-1 (plasma) and 0.5 to 200 µg mL-1 ( urine). The intra- and inter-assay coefficient of variation were 6.14 and 8.7%, and 5.18 and 8.3%, for plasma and urine, respectively; the respective recoveries were 48.9 and 66.5%.
Fludalanine Blood Plasma Urine HPLC Fluorescence

"High Performance Liquid Chromatographic Analysis Of Guanidino-compounds Using Ninhydrin Reagent. 2. Guanidino-compounds In Blood Of Patients On Haemodialysis Therapy"
J. Chromatogr. B 1985 Volume 342, Issue 1 Pages 269-275
Yayoi Hiraga and Toshio Kinoshita

Abstract: Serum was deproteinized with 60% trichloroacetic acid and centrifuged. The supernatant solution was adjusted to pH 2.0 to 2.5 and analyzed by HPLC at 50°C on an ISC-05 ion-exchange column (3.8 x 4.6 mm) with gradient elution with 0.05 M trisodium citrate (pH 3.5) and 0.12 M trisodium citrate containing 0.5 M NaCl and 0.1 M H3BO3 (pH 11.4). The eluate was treated with aqueous 0.6% ninhydrin and 1.5 M NaOH at 50°C, and the fluorescence was measured at 500 nm (excitation at 395 nm). Ten guanidino-compounds were separated in 37 min. The day-to-day coefficient of variation (n = 10) were 0.7 to 3.0% and recoveries were 94 to 108%.
Guanidino compounds Blood Serum HPLC Ion exchange Fluorescence

"Analyser Of Adenine Nucleotides"
J. Chromatogr. B 1985 Volume 344, Issue 1 Pages 345-350
Masanori Yoshioka, Zenzo Tamura, Masaaki Senda and Tadashi Miyazaki

Abstract: A HPLC apparatus with post-column reactor is described. The system comprised a column (3.5 cm x 4.6 mm) of Hitachi gel No. 3012-N (7 µm), at 45°C, with a mobile phase (0.1 mL min-1) of 0.025 M citric acid - 0.05 M Na2HPO4 - 0.4 M NaCl (pH 5) containing 20% of acetonitrile and 0.1 M bromoacetaldehyde; the eluate was heated in a reaction coil (30 m x 0.1 mm) at 100°C and detection of the fluorescent products was at 400 nm (253.7-nm excitation). The calibration graphs for adenosine, AMP, cAMP, ADP and ATP were rectilinear for 0.5 to 10 pmol of each injected, and the intra- and inter-assay coefficient of variation were 0.6 to 1.3 and 0.9 to 1.5%, respectively.
Adenine nucleotides HPLC Fluorescence

"Simultaneous Determination Of Serum Uremic Toxins, Cations And Anions And Urea Determination By Post-column Colorimetry Using Immobilized Enzyme"
J. Chromatogr. B 1986 Volume 378, Issue 1 Pages 95-108
Hideharu Shintani

Abstract: A column-switching method for the simultaneous determination of serum uraemic toxins (e.g., methylguanidine, creatinine and uric acid), urea, cations (e.g., Ca(II), Mg(II), Na+, NH4+ and K+) and anions (e.g., Cl-, ClO4- and HCO3-) is described. Uraemic toxins are determined by ion-pair reversed-phase HPLC on a column (20 cm x 4.6 mm) of Senshupak ODS-SSC-L-1202, with 1 mM Ba hexanesulfonate containing 30 mM BaClO4 as the mobile phase (1 mL min-1) and 210-nm detection. Urea is determined on an immobilized-urease column operated at 55°C with post-column derivatization with indophenol; detection is at 580 nm. Serum cations are determined on a Oyobunko pellicular cation-exchange resin (ASC-4000) column (25 cm x 4.6 mm) with, e.g., 0.37 mM m-phenylenediamine as the mobile phase and conductometric detection. Serum anions are determined on a Wescan anion-exchange column (24 cm x 4.6 mm) with 4 mM K H phthalate (pH 4.5) as the mobile phase. No matrix effects are observed.
Methylguanidine Creatinine Uric acid Urea Ammonium Calcium(2+) Magnesium Potassium Sodium chlorate Chloride Bicarbonate Blood Serum HPLC Conductometry Ion exchange Spectrophotometry

"Method For The Sensitive Analysis Of Individual Molecular Species Of Phosphatidylcholine By High Performance Liquid Chromatography Using Post-column Fluorescence Detection"
J. Chromatogr. B 1987 Volume 415, Issue 1 Pages 241-251
Anthony D. Postle

Abstract: Total phosphatidylcholine(I) in CHCl3 extracts of rat liver and lung was isolated from other phospholipid classes by HPLC on a column (30 cm x 4.9 mm) of µPorasil (10 µm) with hexane - propan-2-ol - water (60:80:9) as mobile phase (1 mL min-1) and detection at 200 nm. The eluate containing I was evaporated and the residue was dissolved in trifluoroethanol for analysis of individual molecular species by reversed-phase HPLC. Columns (25 cm x 4.6 mm) of µBondapak C18 (10 µm), Spherisorb ODS 1 and ODS 2 (5 µm), and Apex ODS 1 and ODS 2 (5 µm) were evaluated with mobile phases (1 mL min-1) of 40 mM choline chloride in methanol - water - acetonitrile. Initial detection was at 200 nm followed by post-column derivatization at 50°C with 1,6-diphenylhexa-1,3,5-triene and fluorescence detection at 460 nm (excitation at 340 nm). The between-run coefficient of variation (n = 10) were 0.32 to 0.68%. The stationary phase Apex ODS 2 gave the most efficient separation, and both saturated and unsaturated species could be determined.
Phosphatidylcholine Liver Lung HPLC Fluorescence

"Sensitive And Selective Determination Of Picogram Amounts Of Ciprofloxacin And Its Metabolites In Biological Samples Using High Performance Liquid Chromatography And Photothermal Post-column Derivatization"
J. Chromatogr. B 1987 Volume 416, Issue 1 Pages 321-330
H. Scholl, K. Schmidt and B. Weber

Abstract: Liquid samples are diluted with 0.033 M H3PO4; faeces are homogenized with water, extracted with CHCl2 - propan-2-ol - 0.3 M H3PO4 (1:5:4) and centrifuged; tissue homogenates are extracted with concentrated HClO4 and concentrated H3PO4 in aqueous 50% methanol. Extracts or sample solution are analyzed on a column (25 cm x 4 mm) of Nucleosil 120-5 C18 (5 µm) at 40°C with 4% tetrabutylammonium hydrogen sulfate in aqueous 7 to 10 or 25 to 30% acetonitrile as mobile phase (2 mL min-1). Detection is by fluorescence at 445 nm (excitation at 278 nm). For some metabolites, post-column derivatization by successive thermolysis and photolysis is required and the reactor used is described. Limits of detection were between 0.2 and 2.2 ng mL-1 of ciprofloxacin and its metabolites. Recoveries were from 71.3 to 116.7% and coefficient of variation (n = 35 to 50) were from 1.7 to 2.7%.
Ciprofloxacin Biological tissue HPLC Fluorescence

"Separation Of Digoxin From Dihydrodigoxin And The Other Metabolites Of High Performance Liquid Chromatography With Post-column Derivatization"
J. Chromatogr. B 1987 Volume 421, Issue 1 Pages 381-386
Belachew Desta

Abstract: Digoxin(I) was separated from dihydrodigoxin(II) and other metabolites by HPLC on a column (25 cm x 4.6 mm) of Ultrasphere ODS (5 µm) with methanol - CH2Cl2 - water - propan-2-ol (41:3:50:6) as mobile phase (0.4 mL min-1) and 254-nm detection. The compounds in the eluate were derivatized with dehydroascorbic acid in HCl solution at 55°C and were detected fluorometrically at 460 nm (excitation at 360 nm). The HPLC system (described and illustrated) makes use of air segmentation and 100% fluid recovery. I and II were well separated from digoxigenin, digoxigenin monodigitoxide and digoxigenin bisdigitoxide. The limit of detection was 10 ng. The method is suitable for analysis of biological fluids in combination with RIA.
Digoxin Dihydrodigoxin HPLC Fluorescence

"Determination Of Oxidizable Inorganic Anions By High Performance Liquid Chromatography With Fluorescence Detection And Application To The Determination Of Salivary Nitrite And Thiocyanate And Serum Thiocyanate"
J. Chromatogr. B 1988 Volume 424, Issue 1 Pages 29-37
Shinzo Tanabe, Michie Kitahara, Masashi Nawata and Kouji Kawanabe

Abstract: Sulfide, SCN-, S2O32- and NO2- were determined by HPLC on a column (15 cm x 4 mm) of TSK gel QAE-2SW (5 µm) with a mobile phase (0.8 mL min-1) of 0.05 M NaNO3 and post-column derivatization, at 80°C for 15 s, with 0.75 M H2SO4 containing 0.25 mM Ce(SO4)2 and 0.003% of sodium bismuthate. Fluorescence detection was at 360 nm (excitation at 260 nm). The limits of detection were 0.1, 0.1, 0.3 and 0.8 nmol for NO2-, SCN-, S2O32- and S2-, respectively. The calibration graphs were rectilinear for 10 nmol per 10 µL injected and the coefficient of variation was <8%. The method was applied in the determination of NO2- and SCN- in saliva and SCN- in serum. Recoveries of NO2- and SCN- were 99.3 and 99.1%, respectively, from saliva and recovery of SCN- from serum was 63%.
Anions, inorganic Nitrite Sulfide Sulfite Thiocyanide Blood Serum Saliva HPLC Fluorescence

"Microassay For GM1 Ganglioside β-galactosidase Activity Using High Performance Liquid Chromatography"
J. Chromatogr. B 1988 Volume 426, Issue 1 Pages 75-82
M. Naoi and M. Kondoh, T. Mutoh, T. Takahashi, T. Kojima, T. Hirooka and T. Nagatsu

Abstract: Brain tissue homogenate was incubated, at 37°C for 1 h, with GM1 ganglioside in 50 mM citric acid - 100 mM sodium phosphate buffer (pH 4.4) containing 100 mM NaCl and 0.5% of Na taurodeoxycholate. After heating at 100°C for 2 min and cooling, mobile phase, viz, 0.5 M H3BO3 - NaOH buffer (pH 8.7) was added and the mixture was centrifuged. The supernatant solution was subjected to HPLC, at 65°C, on a column (25 cm x 4.0 mm) of Shimadzu ISA-07/S2504 at 0.6 mL min-1 and with post-column derivatization by heating the eluate with 2% L-arginine - 3% H3BO3 and after cooling, fluorimetric detection at 430 nm (excitation at 320 nm). The calibration graph was rectilinear for 1 mmol of β-galactose.
Enzyme, galactosidase Brain HPLC Fluorescence

"Fluorimetric Determination Of Urinary δ-aminolaevulic Acid By High Performance Liquid Chromatography And Post-column Derivatization"
J. Chromatogr. B 1988 Volume 426, Issue 1 Pages 365-369
Akira Okayama

Abstract: Urine was mixed with 10% trichloroacetic acid, and the solution was centrifuged. The supernatant solution was subjected to HPLC on a column (15 cm x 6 mm) of TSK-GEL SCX (5 µm) with stepwise gradient elution (flow rate 1 mL min-1) with 0.01 M NaH2PO4 buffer (pH 3) and 0.01 M Na2HPO4 - 0.05 M NaOH (program illustrated). The eluate was mixed, at 95°C, with 18.5% formaldehyde solution in 2 M acetic acid and then with water - ethanol - acetylacetone (1:1:2) and the fluorescence was measured at 473 nm (excitation at 363 nm). The calibration graph was rectilinear for 0.25 to 50 mg L-1 of 5-aminolaevulic acid, and the limit of detection was 100 pg. The within- and between-day coefficient of variation at the 200 ng level were 1.2 and 2.5%, respectively. The mean recovery was 100.2%.
δ-Aminolevulinic acid Urine HPLC Fluorescence

"High Performance Liquid Chromatographic Determination Of Substance P-like Arginine-containing Peptide In Rat Brain By Online Post-column Fluorescence Derivatization With Benzoin"
J. Chromatogr. B 1989 Volume 490, Issue 1 Pages 301-310
Masahiro Ohno, Masaaki Kai and Yosuke Ohkura

Abstract: Brain homogenate, containing [D-Phe11]neurotensin as internal standard, was deproteinized by centrifugation with acetone. The supernatant solution was mixed with 1 M NaHCO3 (0.22 ml) and 0.1 M Na2EDTA (0.5 ml), the ppt. was removed by centrifugation, the acetone was evaporated off and the residue was dissolved in water (2 ml). The solution was cleaned up on a Bond Elut C18 cartridge (details given), the eluate was evaporated and the residue was dissolved in water. A portion (100 µL) of solution was analyzed by HPLC on a column (20 cm x 4 mm) of TSKgel ODS-120T (5 µm) with gradient elution (1 mL min-1) with acetonitrile - 0.3 M sodium phosphate buffer (pH 2.3) - water. The eluate was mixed with a stream (1 mL min-1) of 2 mM benzoin - 1.6 M KOH - 0.7 M 2-mercaptoethanol in a PTFE coil (15 m x 0.3 mm) at 76°C and then with a stream (0.4 mL min-1) of 0.5 M Tris - 2.1 M HCl before fluorimetric detection at 435 nm (excitation at 325 nm). The calibration graph was rectilinear up to 320 pmol of substance P. The detection limit for substance P-like arginine-containing peptide was 580 fmol mg-1 of protein.
Arginine Peptides Brain HPLC Fluorescence

"Measurement Of Histamine In Rat Bronchoalveolar Lavage Fluid By High Performance Cation-exchange Chromatography Coupled With Post-column Derivatization To O-phthaldialdehyde"
J. Chromatogr. B 1992 Volume 574, Issue 2 Pages 340-343
T. A. Neubecker, N. S. Miller, T. N. Asquith* and K. E. Driscoll

Abstract: Histamine (I) was determined in bronchoalveolar lavage fluid (100 µL) by cation-exchange HPLC on a column (10 cm x 4.6 mm) of Partisil 5 SCX RAC II (5 µm) with Si-saturated 0.17 M KH2PO4 as mobile phase (1 mL min-1). The column eluate was mixed with phthalaldehyde reagent solution (pH 11.7 to 12.0) in a turbulent mixer and the reaction mixture was passed to a reaction coil (305 cm x 0.5 mm) maintained at 65°C. Fluorimetric detection was at 418 nm (excitation at 230 nm). The calibration graph was rectilinear from 1 to 65 ng mL-1 of I. The coefficient of variation (n = 4) were 1.8 to 6.0% for 3.28 to 16.4 ng mL-1 of I. Day-to-day coefficient of variation were 2.7 to 6.4%. Average recovery was 94.2%.
Histamine Rat Fluid HPLC Fluorescence

"Analysis Of 6R- And 6S-tetrahydrobiopterin And Other Pterins By Reversed-phase Ion-pair Liquid Chromatography With Fluorimetric Detection By Post-column Sodium Nitrate Oxidation"
J. Chromatogr. B 1993 Volume 617, Issue 2 Pages 249-255
Yoshihiro Tani* and Tomochika Ohno

Abstract: A mixture of D-neopterin, biopterin, pterin, 7,8-dihydropterin, 6R-L-erythro-5,6,7,8-tetrahydrobiopterin and 6S-L-erythro-5,6,7,8-tetrahydrobiopterin was analyzed by HPLC at 40°C on a column (25 cm x 4.6 mm) of Cosmosil 5C18 equipped with a guard column (5 cm x 4.6 mm) of the same packing. Elution (1 ml/min) was effected with 0.1 M phosphate buffer of pH 3 containing 5% methanol, 3 mM sodium octylsulfate, 0.1 mM Na2EDTA and 0.1 mM ascorbic acid. Post-column derivatization was achieved by mixing the eluate with a stream of 5 mM NaNO2 (1 ml/min) before passing through a reaction coil (no dimensions given) at 80°C; fluorescent detection was performed at 440 nm (excitation at 350 nm). The calibration graphs were linear from 0.02-5 ng of each compound injected, with detection limits of 10^-20 pg. Recoveries from tissues ranged from 84.7-99.6% and the within-assay RSD were 0.7-3.7%. The method was applied to the analysis of homogenates of rat liver, kidney and 6 regions of the brain.
d-Neopterin Biopterin Pterin 7,8-Dihydropterin 6R-L-erythro-5,6,7,8-tetrahydrobiopterin 6S-l-erythro-5,6,7,8-tetrahydrobiopterin Brain Kidney Liver Fluorescence HPLC

"High Performance Liquid Chromatographic Determination Of Branched-chain 2-oxo-acids In Serum Using Immobilized Leucine Dehydrogenase As Post-column Reactor"
J. Chromatogr. B 1989 Volume 497, Issue 1 Pages 236-242
Nobutoshi Kiba, Masakazu Muto and Motohisa Furusawa

Abstract: Serum (0.2 ml), containing 20 µL of 0.3 mM 2-oxohexanoic acid as internal standard, was passed through a membrane filter (mol. wt. 30,000), and a 30 µL portion of filtrate was injected on to a column (15 cm x 4 mm) and guard column (1 cm x 4 mm) of Capecell 120 C18 (5 µm), at 40°C. The mobile phase (0.8 mL min-1) was 0.5 M NH4Cl - NH3 buffer of pH 8.5 containing 5 µM-NADH. The eluate was passed through a column (5 cm x 4 mm), also at 40°C, of immobilized leucine dehydrogenase before fluorimetric detection of 2-oxo-acids, e.g., 2-oxo-butyric acid and 2-oxo-pentanoic acid. Calibration graphs were rectilinear in the range 4 to 55 µM. Detection limits were 1 µM. Recoveries were 53.5 to 56.5%, and coefficient of variation were 1.7 to 2.4% (n = 5). Results are compared with those of a direct HPLC method.
Acids Blood Serum HPLC Fluorescence

"Comparison Of Different Flow Injection Approaches To The Automatic Determination Of Enzymic Activity"
J. Pharm. Biomed. Anal. 1989 Volume 7, Issue 3 Pages 295-302
J. M. Fernandez-Romero*, M. D. Luque de Castro and M. Valcarcel

Abstract: A comparative study of normal, stopped-flow and open-closed flow injection assay of lactate dehydrogenase is presented (details given). Optimum pH, temp., buffer solution, NADH concentration. and flow rate were 7, 40°C, 0.1 M K2HPO4, 1.0 mM NADH and 1.64 mL min-1, respectively, for all three methods. Pyruvate concentration, reactor length and injected volume were variable. Advantages, reproducibility and sensitivity of the methods are discussed. Three configurations based on the principles behind flow injection analysis (FIA) are proposed for the automatic determination of enzymatic activity. The proposed approaches are normal, stopped-flow and open-closed FIA. The comparative study of the methods developed from these approaches allows the establishment of the scope of the application of each, with inherent advantages and disadvantages.
Enzyme, lactate dehydrogenase Spectrophotometry

"Oxidative Column For The Flow Injection Analysis - Spectrophotometric Determination Of Paracetamol"
J. Pharm. Biomed. Anal. 1989 Volume 7, Issue 10 Pages 1165-1172
J. Martinez Calatayud* and S. Sagrado Vives

Abstract: In a flow injection system, paracetamol was oxidized4 at room temperature in ammoniacal solution with K3Fe(CN)6 immobilized on an anion-exchange column. The N-acetyl-p-benzoquinonimine produced was allowed to react at 80°C with phenol, giving a blue product the absorbance of which was measured at 630 nm. The calibration graph was rectilinear from 0.20 to 20 ppm and the coefficient of variation was 0.6% (n = 40). Throughput was 42 samples per h. Paracetamol was determined in several pharmaceutical formulations.
Acetaminophen Pharmaceutical Spectrophotometry

"Spectrophotometric Determination Of Adrenaline With An Oxidative Column In A FIA Assembly"
J. Pharm. Biomed. Anal. 1990 Volume 8, Issue 8-12 Pages 663-666
A. Kojo and J. Martinez Calatayud*

Abstract: A single channel FIA assembly is proposed for the spectrophotometric determination of adrenaline, the aqueous sample solution is directly injected into the carrier stream leading the sample through a manganese dioxide column at 80°C, and on to the spectrophotometer flow-cell. The calibration graph is linear up to 17 ppm of adrenaline. The influence of other substances has been studied and the method has been applied to the determination of adrenaline in a pharmaceutical formulation. Sample solution (348.8 µL) was injected into a carrier stream (0.55 mL min-1) of distilled and de-areated water and passed through a column of MnO2, the carrier solution, sample loop and column were maintained at 80°C. The absorbance of the oxidized sample was measured at 300 nm. The calibration graph was rectilinear up to 17 ppm of adrenaline and the detection limit was 0.05 ppm. Coefficient of variation was 0.19% (n=11). Sample throughput was 45 h-1. Interference was present from procaine, amethocaine and picric acid.
Adrenaline Pharmaceutical Spectrophotometry

"Determination Of Medroxyprogesterone Acetate In Serum By HPLC With Peroxyoxalate Chemiluminescence Detection Using A Fluorogenic Reagent, 4-(N,N-dimethylaminosulfonyl)-7-hydrazino-2,1,3-benzoxadiazole"
J. Pharm. Biomed. Anal. 1992 Volume 10, Issue 10-12 Pages 979-984
S. Uzu, K. Imai*, K. Nakashima and S. Akiyama

Abstract: Serum was centrifuged with acetonitrile at 10,000 g for 1 min and the supernatant solution was mixed with water and applied to a Bond-Elut C18 column. After washing with aqueous 40 and 45% acetonitrile, elution was effected with aqueous 70% acetonitrile. The eluate was evaporated to dryness, dissolved in 0.25 mM 4-(NN-dimethylaminosulfonyl)-7-hydrazino-2,1,3-benzoxadiazole and 0.25% trifluoroacetic acid in acetonitrile and set aside at 4°C for 5 h or overnight. A portion of the reaction mixture was analyzed by HPLC on a column (25 cm x 4.6 mm) of TSKgel ODS 80 (5 µm) in series with a guard column of the same material maintained at 30°C with a mobile phase (0.5 mL min-1) of THF - 100 mM imidazole nitrate buffer of pH 6 (31:19) and post-column derivatization with 0.5 mM bis[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)-phenyl]oxalate and 2.5 mM H2O2 in acetonitrile - ethyl acetate (1:1) followed by chemiluminescence detection. The calibration graph was rectilinear from 15.6 to 96.6 ng mL-1 of medroxyprogesterone acetate (I) with a detection limit of 9 ng mL-1. Coefficients of variation were 7.4 and 1.7% for 19.3 and 77.3 ng mL-1 of I, respectively.
Medroxyprogesterone Blood Serum HPLC Chemiluminescence

"Flow Injection Spectrophotometric Determination Of Adrenaline And Dopamine With Sodium-hydroxide"
J. Pharm. Biomed. Anal. 1996 Volume 14, Issue 5 Pages 571-577
J. J. Berzas Nevado*, J. M. Lemus Gallego and P. Buitrago Laguna

Abstract: A new, rapid and economical flow injection method for determining adrenaline and dopamine is proposed on the basis of the hydrolysis of these compounds in alkaline medium. The method was optimized by using a spectrophotometer operating at lambda = 390 nm as detector. Calibration graphs were linear up to 2 x 10^-4 M with quantification limits of 2.5 x 10^-6 M and 3.3 x 10^-6 M for dopamine and adrenaline respectively. Flow injection allows the measurement of 130 samples per hour. The method was successfully applied for the determination of catecholamines in pharmaceuticals. A flow injection spectrophotometric method for the determination of adrenaline (I) and dopamine (II) in pharmaceuticals, based on their hydrolysis to colored aminochrome derivatives in alkaline medium, is presented. Pharmaceutical formulations were diluted appropriately with 50 mM acetate buffer of pH 4.8 and a 350 µL portion was injected into a stream of water carrier solution (2 ml/min) heated at 65°C in a flow injection manifold (schematic shown). The sample stream was merged with a reagent stream of 0.4 M NaOH flowing at the same rate and the mixture was pumped through a reactor (2.7 m x 0.5 mm i.d.) and the products were detected at 390 nm in a flow cell. Beer`s law was obeyed up to 200 µM-I and -II and the corresponding detection limits were 0.76 and 0.97 µM. The method was applied to the analysis of three pharmaceutical preparations (listed). Results were in good agreement with labelled values.
Catecholamines Adrenaline Dopamine Norepinephrine Epinephrine Pharmaceutical Spectrophotometry

"Flow Injection Spectrophotometric Determination Of Frusemide Or Sulfathiazole In Pharmaceuticals"
J. Pharm. Biomed. Anal. 1997 Volume 15, Issue 4 Pages 453-459
M. S. Garc&iacute;a, C. Sanchez-Pedre&ntilde;o*, M. I. Albero and V. R&oacute;denas

Abstract: Powdered tablets equivalent to 40 mg frusemide (I) or 50 mg sulfathiazole (I) were sonicated for 5 min with 0.6 mL and 1 mL 1 M NaOH, respectively, then diluted to 100 mL with water. Injection solutions were dissolved in water. Portions (72 µL) were injected into a carrier stream of water (1.2 ml/min) which merged with a stream (1.2 ml/min) of 3 mM PdCl2 in Britton-Robinson buffer of pH 5 and passed through a reactor (3 m x 0.5 mm i.d.) maintained at 55°C before the absorbance was measured at 410 nm. The calibration graphs were linear for 20-400 µM-I and 50-300 µM-II, the detection limits were 55 µM and 14 µM, respectively, and the RSD were 0.3% and 0.9%, respectively, (n = 10) at 0.2 mM I. The sampling frequency was 50/h. No interference was observed from ethacridine or ephedrine ricinoleate. Results agreed with those obtained by reference methods (spectrophotometry for I and amperometric titrimetry for II). Recoveries were >=98.9%. Two sensitive and fast flow injection spectrophotometric methods are proposed for the determination of frusemide or sulfathiazole based on the formation of colored complexes between these compounds and Pd(II) at pH 5.0 and 55°C. Using the peak height as a quantitative parameter, frusemide or sulfathiazole was determined at 410 nm over the range 2.0 x 10^-5-4.0 x 10^-4 M or 5.0 x 10^-5-3 x 10^-4 M, respectively. The methods were applied to the determination of these sulfonamides in pharmaceuticals.
Frusemide Sulfathiazole Pharmaceutical Sample preparation Spectrophotometry

"Flow-through Biosensor For Sequential Determination Of Total And Prostatic Acid Phosphatase Activity"
Sens. Actuat. B 1995 Volume 23, Issue 1 Pages 9-15
M. S&aacute;nchez-Cabezudo, J. M. Fern&aacute;ndez-Romero and M. D. Luque De Castro

Abstract: Sample (900 µL) diluted 1:5 in 100 mM trisodium citrate dihydrate of pH 4.8 (buffer A) was injected into a carrier stream (1.3 ml/min) of buffer A which merged with a stream of 0.27 mM p-nitrophenylphosphate in buffer A and passed through a reactor coil (250 cm x 0.5 mm i.d.) for hydrolysis. The p-nitrophenol produced was derivatized with 150 mM NaOH in a reactor coil (100 cm x 0.5 mm i.d.). The reaction product was absorbed on Dowex-1 anion-exchange resin (100-200 mesh; chloride form) contained in a biosensor constructed from a 1 mm path length flow cell (details given) for enhancement of detection at 405 nm. The product was eluted from the biosensor with 100 mM EDTA (disodium salt). The system was operated at 40°C. Inhibition of the prostatic acid phosphatase fraction was achieved with 50 mM L-(+)-tartaric acid. The calibration graph was linear for 0.2-20 iu/l of total acid phosphatase (TAP) and the RSD were 0.6-1.5%. The calibration graph for a conventional FIA method without use of the biosensor (details given) was linear for 5-300 iu/l of TAP and the RSD were 1.6-3.3%. Recoveries of TAP and prostatic acid phosphatase from serum were 95-102% and the results agreed well with those using the conventional method.
Acid phosphatase Blood Serum Sensor Spectrophotometry

"Flow Injection Analysis System With Glass-bonded ISFETs For The Simultaneous Detection Of Calcium And Potassium Ions And PH"
Sens. Actuat. B 1991 Volume 4, Issue 3-4 Pages 239-241
B. H. van der Schoot, H. H. van den Vlekkert and N. F. de Rooij, A. van den Berg and A. Grisel

Abstract: A flow-through cell is described, based on a glass body to which four single ISFETs are sealed by anodic bonding at 50°C and 800 V. Micropools 200 µm deep and 550 µm in diameter are formed around the ISFET gates, and PVC-based membranes sensitive to Ca2+, K+ and pH are cast into 3 of the cavities. A pH-sensitive ISFET covered with a diffusion-delaying hydrogel layer is used as a pseudo reference electrode for the 3 sensors. Provision of a glass cover creates a 1-mm diameter channel and the internal cell volume is as small as 12 µL. When evaluated as part of a FIAstar flow injection analysis system, the response was rapid: >200 samples h-1 could be analyzed and the cross-talk between sensors was negligible.
Calcium pH Potassium Electrode Field effect transistor

"Online Precipitation/dissolution System For The Preconcentration And Determination Of Manganese Traces By Atomic Absorption Spectrometry"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1935-1941
Carola Dittfurth, Evaristo Ballesteros, Mercedes Gallego and Miguel Valc&aacute;rcel*

Abstract: Sample solution (8 or 24 ml; pH 3), containing 40-720 ng of Mn, was injected into a carrier stream of 0.5% H2O2 (at 4 ml/min) and merged with a reagent stream of ammoniacal buffer solution of pH 9 (4 ml/min). The combined streams were heated at 40°C, and the resulting hydrated Mn(IV) oxide was collected on a stainless-steel filter (3 cm2; pore size 0.5 µm). The Mn collected on the filter was dissolved by a stream of 2 M HNO3 (1 ml/min) and carried to a fuel-lean air-acetylene flame. Enrichment factors of up to 55 were obtained. For 8 and 24 mL samples the calibration graphs of peak heights were linear for 5-90 and 1.3-30 ng/ml of Mn and the detection limits were 2 and 1 ng/ml, respectively. Results for digests of biological reference materials agreed with the certified values.
Manganese Biological material Sample preparation Spectrophotometry

"Use Of A Robot And Flow Injection For Automated Sample Preparation And Analysis Of Used Oils By ICP Emission Spectrometry"
Spectrochim. Acta B 1987 Volume 42, Issue 1-2 Pages 169-180
M. P. Granchi, J. A. Biggerstaff, L. J. Milliard and P. Grey

Abstract: The system comprises, inter alia, a Zymark laboratory robot, a balance, a hotplate, an SC-110 automatic sample changer, a FIAtron model SHS-300 microprocessor-controlled flow injection solution-handling system (FIAtron Systems, Oconomowoc, WI), an ICP emission spectrometer controlled by a PDP-11/34 minicomputer, and an IBM/XT personal computer. The personal computer co-ordinates the activities of the microprocessor and the PDP-11/34 (used for data acquisition, background correction and calculation of results) corrects for spectral interference, displays the results on a printer and stores them on floppy disc, and, with the approval of the operator, transmits them to a laboratory information-management computer. The robot is programmed to perform the various sample-preparation steps (heating at ~70°C for 35 min, dilution with xylene, and weighing). The precision of the transient signal integration was at least an order of magnitude better than for conventional steady-state integration, and results by the two types of measurement were equivalent.
Metals, wear Oil Sample preparation Spectrophotometry

"Flow Injection Analysis For Hydrogen Peroxide By Using Immobilized Horseradish Peroxidase And Its Fluorogenic Substrate 3-(p-hydroxyphenyl) Propionic Acid"
Anal. Sci. 1985 Volume 1, Issue 1 Pages 65-68
Yohji HAYASHI, Kiyoshi ZAITSU and Yosuke OHKURA

Abstract: The sample solution (20 µL) was injected into a carrier stream (0.5 mL min-1) of water that then merged with a stream (0.5 mL min-1) of 10 mM 3-(4-hydroxyphenyl)propionic acid in 0.2 M Tris - HCl buffer that was 0.3 M in NaCl (pH 8.5). The combined streams passed through a mixing coil and a PTFE tube (8 cm x 0.5 mm) packed with horse-radish peroxidase immobilized on controlled-pore glass beads (prep. described), both at 37°C, and then through a fluorescence detector (excitation at 305 nm, emission at 405 nm), the peak height being recorded. The best-shaped peaks were obtained with flow injection tubing of 0.25 mm i.d. The calibration graph was rectilinear up to 1 nmol of H2O2 and slightly curvilinear up to 1.5 nmol, and the limit of detection was 0.5 pmol. The coefficient of variation (n = 10) for 1, 10 and 100 pmol and 1 nmol of H2O2 were 3.6, 0.68, 0.35 and 0.24%, respectively, and the sampling rate was up to 120 h-1.
Hydrogen peroxide Fluorescence

"Fluorimetric Catalytic Determination Of Iodide By Flow Injection Analysis"
Anal. Sci. 1986 Volume 2, Issue 2 Pages 197-198
A. TANAKA, K. OBATA and T. DEGUCHI

Abstract: Iodide is determined from its catalytic effect on the reaction between Ce(IV) and As(III). Flow diagrams are given of two flow injection systems. The sample (0.36 ml) is introduced into a fresh mixture (1:1) of 2 mM Ce(IV) and 2 mM As(III), each in 0.1 M H2SO4. After the mixture has passed through a 3-m coil heated at 90°C, it is either cooled for direct spectrofluorimetric measurement of Ce(III) at 350 nm (excitation at 254 nm) or mixed with 2 mM 8-hydroxyquinoline-5-sulfonic acid to form a quinone by reaction with unconsumed Ce(IV), the fluorescence in this instance being measured at 480 nm (excitation at 365 nm). Detection limits are 3.0 nM with measurement of Ce(III) and 50 nM with measurement of Ce(IV); corresponding coefficient of variation are 0.3% at 30 nM-I- and 1.0% at 100 nM (n = 3). Thirty samples can be analyzed in 1 h.
Iodide Fluorescence

"Simultaneous Determination Of Three Species By Flow Injection Analytical Method Using Enzyme-immobilized Open Tubular Reactors"
Anal. Sci. 1986 Volume 2, Issue 5 Pages 411-415
F. MORISHITA, Y. NISHIKAWA and T. KOJIMA

Abstract: A flow injection analysis method with enzyme-immobilized reactors in parallel is described for the simultaneous determination of L-lactate, β-D-glucose and glycerol. The enzymes immobilized in the reactors were L-lactate dehydrogenase, glucose dehydrogenase and glycerol dehydrogenase. The carrier solution was 33 mM phosphate buffer (pH 8.0) containing 2 mM NAD+, 1 mM EDTA and 0.1 mM dithiothreitol. Determination (of resulting NADH) was by fluorescence at 470 nm (excitation at 340 nm). Optimization of the system is discussed.
Lactate d-Glucose Glycerol Fluorescence

"Determination Of Glucose By Flow Injection Analysis With Merging-zone Technique"
Anal. Sci. 1987 Volume 3, Issue 2 Pages 181-183
K. UCHIDA, D. YOSHIZAWA, M. TOMODA and S. SAITO

Abstract: The sample is injected into a flow stream of phosphate buffer (pH 6.95) containing 0.15 M NaCl and 6% of Triton X-100. An Iatrochrome GLU-Lq enzyme kit (Iatron Laboratories) reagent containing aldose 1-epimerase (1.6 iu mL-1), glucose oxidase (17 µiu mL-1), peroxidase (5.6 miu mL-1) and 1 mM aminoantipyrine is injected into a reagent stream containing the same liquid carrier. The flow rates for the sample and reagent streams are 0.5 and 2.0 mL min-1, respectively. The flow streams are mixed in a reaction coil at 45°C and the eluate is monitored at 580 nm. The calibration graph is rectilinear for up to 180 mg L-1 of glucose (r = 0.9998); recovery is >95% and the coefficient of variation (n = 3) is <1%. The method is applicable for the determination of glucose in human plasma. Interference caused by ascorbic acid is eliminated by addition of L-ascorbate oxidase.
Glucose Plasma Human Clinical analysis Spectrophotometry

"Spectrophotometric Flow Injection Analysis Of Silicates For Manganese"
Anal. Sci. 1987 Volume 3, Issue 3 Pages 251-255
K. OGUMA, K. NISHIYAMA and R. KURODA

Abstract: Powdered silicate rock (100 mg) was fused with anhydrous Li2CO3 - H3BO3 (1:1) at ~1000°C for 15 min. The melt was dissolved in 1 M HCl and diluted. Aliquots of sample solution were treated with HF and HClO4, the mixture was evaporated, the residue was moistened with HClO4 and the acid was evaporated. The residue was dissolved in 1 M HCl, the solution was applied to a column (7 cm x 8 mm) of cellulose phosphate (Whatman P-11) and Mn was eluted with 1 M HCl. An aliquot of the eluate and 1% aminoethanethiol hydrochloride were injected into 1 M HCl and water (carrier solution), respectively, and after mixing, the combined solution was mixed with 0.36 M formaldoxime in NH3 buffer solution (pH 10.5) and passed through a reaction coil in a water bath at 80°C. The absorbance was monitored at 452 nm. The flow injection manifold used is described (with diagram). The coefficient of variation (n = 10) were 0.8 and 0.33%, respectively, for 0.5 and 2 ppm of Mn. The sampling rate was 45 h-1.
Manganese Silicate Spectrophotometry

"Fluorimetric Determination Of Guanidino-compounds By High Performance Liquid Chromatography Using Water-soluble 9,10-dioxophenanthrene-3-sulfonate"
Anal. Sci. 1987 Volume 3, Issue 4 Pages 363-367
Y. KOBAYASHI, H. KUBO and T. KINOSHITA

Abstract: Serum samples (100 µL) were treated with 20% trichloroacetic acid (20 µL) and the mixture was centrifuged. A 60 µL portion of the supernatant solution was treated with 0.4 M NaOH (15 µL) and the solution (adjusted to pH 2.5 to 3.0) was analyzed by HPLC on a column (7.5 cm x 4.6 mm) of Nucleosil C8 (3 µm). The mobile phase (1 mL min-1) consisted of 5 mM Na octanesulfonate and 2 mM K 9,10-dioxophenanthrene-3-sulfonate in water - acetonitrile - methanol (93:2:5). Post-column derivatization was effected by heating the eluate to 80°C in a reaction coil (10 m x 0.5 mm) with 0.6 M NaOH as carrier solution. Fluorimetric detection was at 520 nm (excitation at 370 nm). The detection limits of nine guanidino-compounds investigated ranged from 6 pmol to 0.1 nmol.
Guanidino compounds Blood Serum HPLC Fluorescence

"Potentiometric Flow Injection Analysis Of Glucose Using Hexacyanoferrate(III)-hexacyanoferrate(II) Potential Buffer"
Anal. Sci. 1987 Volume 3, Issue 5 Pages 453-456
H. OHURA, T. IMATO, S. YAMASAKI and N. ISHIBASHI

Abstract: Glucose solution (140 µL) were injected into a water carrier stream which merged with the reagent stream, consisting of a buffer solution of Fe(CN)63- - Fe(CN)64- containing 0.6 M NaOH, and allowed to react in a coil heated to 85°C and then passed through a cooling coil at 25°C. The p.d. of a Pt electrode in the resulting stream was measured vs. a Ag - AgCl reference electrode. The effect on response of reaction temperature and buffer concentration. in the reagent stream was investigated. Response was rectilinear for 0.1 to 2 mM or 0.25 to 2.5 µM-glucose for buffer concentration. of 10 mM and 10 µM, respectively; the detection limit was 0.1 µM-glucose, achieved with use of 10 µM-buffer.
Glucose Electrode Potentiometry

"Flow Injection Analysis Of Feed And Premix For Monensin And Salinomycin"
Anal. Sci. 1987 Volume 3, Issue 5 Pages 441-444
Y. SUZUKI, N. ARAI and M. OKAMOTO

Abstract: Samples (5 g) of feed or pre-mix were extracted with 100 mL of ethanol for 15 min and, after filtration, the filtrate was analyzed by flow injection spectrophotometry. Sample solution (100 µL) was injected into the carrier solution (ethanol; 0.5 mL min-1), this stream was mixed with the reagent solution (0.5 mL min-1) consisting of ethanolic 1% H2SO4 - 1% 4-dimethylaminobenzaldehyde, and the resulting stream was allowed to react in a coil at 78°C. The absorbance of the effluent was measured at 578 nm for monensin and 600 nm for salinomycin. Calibration graphs were rectilinear for 2 to 10 ppm for both analytes. Recoveries ranged from 96.9 to 103.2%. Analysis time was ~20 min.
Monensin Salinomycin Feed Spectrophotometry

"Fluorimetric Flow Injection Analysis Of Saliva For Nitrite"
Anal. Sci. 1987 Volume 3, Issue 6 Pages 549-551
T. OHTA, Y. ARAI and S. TAKITANI

Abstract: Saliva (100 to 150 mg) is diluted to 20 mL with water, ultrasonically agitated and centrifuged. A portion of the supernatant solution (210 µL) is injected into a carrier stream of water (0.6 mL min-1), which is successively mixed with 6 mM 4-hydroxycoumarin in acetonitrile - 4 M HCl (1:1), 40 mM Na2S2O3 and 3.5 M NaOH at 0°C, room temperature and 100°C, respectively, to give 3-amino-4-hydroxycoumarin. Fluorescence is measured at 455 nm (excitation at 345 nm). Recovery of added NO2- is in the range 95 to 102%. The method is calibrated up to 10 µg mL-1, with a detection limit of ~2 ng mL-1 and coefficient of variation (n = 8) of 2.8 and 1.7% at 20 and 100 ng mL-1, respectively. The sampling rate is 30 h-1.
Nitrite Saliva Fluorescence

"Flow Injection Spectrophotometric Determination Of Trace Amounts Of Bromide By Its Catalytic Effect On The Hydrogen Peroxide Oxidation Of Pyrocatechol Violet"
Anal. Sci. 1988 Volume 4, Issue 3 Pages 273-276
N. YONEHARA, S. AKAIKE, H. SAKAMOTO and M. KAMADA

Abstract: Trace amounts of Br- were determined by flow injection analysis, by using a 10-m reaction coil operated at 37°C; 500 µL of sample solution was injected into the water carrier stream, which was then mixed with 3.5 M H2O2 and 0.1 or 0.05 mM catechol violet in 2.3 M HCl, with subsequent detection at 550 nm. The calibration graph was rectilinear from 10 to 600 µg L-1 of Br-; coefficient of variation were 2.5 and 1.4% for 20 and 105 muwg L-1 of Br-, respectively (n = 10), and recovery was 90 to 107%. Many common ions did not interfere, and the interference of others was reduced by using flow injection analysis; I- interfered at 200 µg l-1, but the effect could be decreased by suitable dilution. The method has been applied to several natural waters.
Bromide Spring River Sea Lake Geothermal Spectrophotometry

"Spectrophotometric Determination Of Silicon In Silicate Rocks By Flow Injection Analysis"
Anal. Sci. 1988 Volume 4, Issue 5 Pages 523-525
T. UCHIDA, K. YAMAMOTO, H. INOUE, I. KOJIMA, and C. IIDA

Abstract: A system is described and illustrated for flow injection spectrophotometric determination of Si. Powdered silicate rock (25 mg) is decomposed with 0.5 mL of HCl and 0.25 mL of HF by repeated (x3) heating and cooling for 1 and 5 min, respectively. After cooling and addition of 5 mL of 4% H3BO3 solution, the mixture is diluted with water. A 65 µL portion is injected into the carrier stream (0.6 M HCl, 2.45 mL min-1), which is then mixed with 3% (NH4)6Mo7O24 solution (2.45 mL min-1). The mixed solution then passes to a 200-cm reaction coil maintained at 45°C, and the absorbance is measured at 415 nm in a flow-through cell. The method is suitable for determination of 200 to 380 µg g-1 of Si. Results for determination of Si in 22 standard rock samples agreed with certified values. The coefficient of variation (n = 5) was 0.4%.
Silicon Silicate CANMET MRG-1 CANMET SY-2 CANMET SY-3 USGS G-1 USGS G-2 USGS W-1 USGS GSP-1 USGS AGV-1 USGS BCR-1 USGS PCC-1 USGS DTS-1 GSJ JG-1 GSJ JB-1 GSJ JA-1 GSJ JA-3 GSJ JP-1 GSJ JGb-1 GSJ JF-1 GSJ JR-1 GSJ JR-2 Sample preparation Spectrophotometry

"Determination Of Total Aliphatic Amines In Alcoholic Drink By Online Liquid-liquid Extraction/flow Injection Analysis"
Anal. Sci. 1988 Volume 4, Issue 5 Pages 537-538
H. KOIZUMI and Y. SUZUKI

Abstract: Sample solution (5 µL) was injected into the carrier solution (10 mM NaOH; 0.4 mL min-1) which was then mixed with reagent solution (Na 1,2-naphthoquinone-4-sulfonate; 0.4 mL min-1). The mixture passed to the reaction coil, which was immersed in a water-bath at 60°C, and, after mixing with segmenting extractant (CHCl3; 0.3 mL min-1), the mixture passed to an extraction coil and thence to a membrane phase separator. The derivatives in the organic phase were detected at 460 nm. The calibration graph for ethylamine was rectilinear from 1.3 to 132 ppm, and the detection limit was 0.5 ppm. The coefficient of variation (n = 10) for 6.6 ppm of ethylamine and 10.4 ppm of propylamine were 2.6 and 1.7%, respectively. The method was applied to determine amines in beer and wine.
Amines, aliphatic Ethylamine Propylamine Beverage Beer Wine Spectrophotometry Sample preparation

"A Flow Injection Technique For Measurement Of Penicillinase Activity"
Anal. Sci. 1988 Volume 4, Issue 5 Pages 493-495
S. KUDOH and H. NAKAMURA

Abstract: The flow injection system consisted of a pre-warming coil (5 m x 0.5 mm) to equilibrate the carrier stream at the reaction temperature and a reaction coil (10 m x 0.25 mm). β-Lactamase(I) solution was injected into the carrier stream (benzylpenicillin sodium solution in 50 mM phosphate buffer of pH 7; 0.6 mL min-1) and the decrease in absorbance at 229 nm, resulting from enzymatic hydrolysis of the benzylpenicillin, was measured. The calibration graph was rectilinear for up to 6 iu mL-1 of I. The detection limit was 0.03 iu mL-1 and the coefficient of variation (n = 18) at 0.07, 0.5 and 2.8 iu mL-1 were 0.65, 0.95 and 2.9%, respectively.
Enzyme, penicillinase Pharmaceutical Spectrophotometry

"Simultaneous Assay Of Aspartate Aminotransferase And Alanine Aminotransferase By Flow Injection Method Using Immobilized Enzyme Reactors"
Anal. Sci. 1988 Volume 4, Issue 6 Pages 579-582
T. SUGAYA, S. NAITO, S. YONEZAWA, F. MORISHITA and T. KOJIMA

Abstract: Flow injection systems for determination of the cited enzymes (I and II, respectively) are described and illustrated. For determination of I, the sample is injected into a carrier stream of 0.3 mM aspartate, 0.05 M α-ketoglutarate, 0.5 mM NADH and 0.1 M Tris buffer (pH 7.5) before passing to a malate dehydrogenase-immobilized reactor maintained at 36°C. After removal of proteins in a column of Toyopearl AF-blue 650MH, I was determined by measuring the decrease in NADH concentration at 470 nm (excitation at 340 nm). For II, sample was separately injected into two carrier streams, one containing 0.3 mM alanine, 0.05 M α-ketoglutarate, 0.5 mM NADH and 0.1 M Tris buffer and the other being the same but without alanine. Each solution passed through a lactate dehydrogenase-immobilized reactor before merging of the solution and proceeding as before. A combined system for simultaneous determination of I and II is also described. The method was applied to determine I and II in serum and results agreed with those obtained by a UV method.
Enzyme, aspartate aminotransferase Alanine aminotransferase Blood Serum Clinical analysis Fluorescence

"Catalytic Determination Of Nanogram Amounts Of Vanadium In Natural Water By Flow Injection Analysis"
Anal. Sci. 1989 Volume 5, Issue 1 Pages 69-72
S. NAKANO, M. TAGO and T. KAWASHIMA

Abstract: A 0.2 mL sample was injected into a carrier stream (0.8 mL min-1), which was then mixed with streams (0.8 mL min-1) of (i) 4 mM 4-aminoantipyrine, 30 mM NN-dimethylaniline and 0.1 M Tiron, (ii) 0.08 M BrO3-, and (iii) 0.15 M formate buffer in a coil (10 m x 0.5 mm) at 55°C. The absorbance was measured at 555 nm. The calibration graph was rectilinear for 0.05 to 2 ng mL-1 of VV; the detection limit was 20 pg mL-1. Coefficients of variation for 1 and 2 ng mL-1 were 0.8 and 0.5% (n = 10), respectively.
Vanadium(V) Environmental Spectrophotometry

"Colorimetric Flow Injection Determination Of Resorcinol-type β2-adrenergic Drugs With Phenanthro[9,10-d]imidazole-2-chloroimide"
Anal. Sci. 1989 Volume 5, Issue 5 Pages 513-516
S. TANABE, T. TOGAWA and K. KAWANABE

Abstract: For the determination of fenoterol hydrobromide, orciprenaline sulfate or terbutaline sulfate, a portion of ground tablets was extracted with 10 mM HCl (30 ml) by shaking for 10 min. The mixture was diluted with 10 mM HCl to 50 ml, filtered, and the filtrate was diluted 10-fold with water before introduction into the flow injection system; 50 mM borate buffer (pH 11.5) was used as carrier solution (0.8 mL min-1), and reaction with ethanolic 0.003% phenanthro[9,10-d]imidazole-2-N-chloroimide was effected in a 1-m PTFE reaction coil (0.33 mm) at 60°C. Absorbance was measured at 530 nm. Calibration graphs were rectilinear from 0.5 to 200 µM for each drug. Recoveries were >99%; the coefficient of variation (n = 10) were better than 2%. The method was also applied to injection solution and syrup.
Drugs Fenoterol hydrobromide Orciprenaline sulfate Terbutaline sulfate Pharmaceutical Pharmaceutical Pharmaceutical Sample preparation Spectrophotometry

"Determination Of Reducing Sugars By High Performance Liquid Chromatography With Post-column Fluorescence Derivatization Using 1,2-bis-(4-methoxyphenyl)ethylenediamine"
Anal. Sci. 1989 Volume 5, Issue 6 Pages 675-680
Y. UMEGAE, H. NOHTA and Y. OHKURA

Abstract: Reducing sugars were separated as their borate complexes by HPLC on a column (15 cm x 4.6 mm) of TSK gel Sugar AXG at 60°C, with 0.5 M borate buffer of pH 8.7 as mobile phase (0.4 mL min-1). Derivatization with the cited reagent was then carried out at 140°C in the presence of NaOH, and the derivatives were detected by fluorimetry at 460 nm (excitation at 330 nm). Serum or urine was deproteinized with acetonitrile in the presence of α-melibiose as internal standard, and borate buffer was added to the centrifuged solution before HPLC. Lactose in urine was hydrolyzed with β-galactosidase at pH 7.3 (phosphate buffer) before the analysis. Response was rectilinear for 0.1 to 10 nmol of reducing sugar injected, and detection limits ranged from 30 to 160 pmol.
Sugars, reducing Urine Blood Serum HPLC Fluorescence

"High Performance Liquid Chromatographic Determination Of Ribonucleotides By Post-column Derivatization Involving Oxidation Followed By Fluorescence Reaction And Its Application To Human Erythrocyte Samples"
Anal. Sci. 1990 Volume 6, Issue 4 Pages 519-522
Y. UMEGAE, H. NOHTA and Y. OHKURA

Abstract: Ribonucleotides such as ATP and ADP were separated on a column (25 cm x 4.6 mm) of TSK gel ODS-80 (5 µm) and converted into fluorescent derivatives by reaction with 1,2-bis-(4-methoxyphenyl)ethylenediamine in acidic medium after oxidation with NaIO4. The detection limits were 14 to 67 pmol injected. The method was applied to human erythrocytes, and showed good sensitivity and high selectivity.
Ribonucleotides Human HPLC Fluorescence

"Potentiometric Determination Of Ethanol In Alcoholic Beverages Using A Flow Injection Analysis System Equipped With A Gas Diffusion Unit With A Microporous Poly(tetrafluoriethylene) Membrane"
Anal. Sci. 1990 Volume 6, Issue 4 Pages 541-546
H. OHURA, T. IMATO, Y. ASANO, S. YAMASAKI and N. ISHIBASHI

Abstract: The method involves the oxidation with K2Cr2O7 of ethanol permeating through a porous membrane, the reduction of unconsumed Cr2O72- with Fe2+ in a flow injection system, and the determination of the Fe3+ produced with a redox electrode. A diagram is presented of the flow injection manifold equipped with a gas diffusion separation unit. Results agreed with those obtained by a specific gravity method and by GC. The method is useful for application to alcoholic beverages owing to its high selectivity, high throughput, low cost and simplicity of operation.
Ethanol Beer Wine Sake Shochu Whisky Potentiometry GC

"Rapid Microdetermination Of Hydroxyproline In Biomedical Samples By Flow Injection Analysis Using Cysteine As An Antioxidant"
Anal. Sci. 1990 Volume 6, Issue 1 Pages 39-44
K. UCHIDA, M. TOMODA, T. SHIBATA, S. IKEUCHI, T. HASEBE, T. MIWA, T. NOMOTO, K. FUKUSHIMA, S. SAITO and S. INAYAMA

Abstract: Tissue samples are hydrolyzed with 6 M HCl, the mixtures are freeze-dried, and the residues are dissolved in 0.01 M cysteine. Portions are injected into a stream of chloramine T solution (0.7 g L-1 in borate buffer of pH 8.7). Passage through a heating coil at 100°C causes hydroxyproline (I) to be oxidized and decarboxylated to pyrrole. Treatment with a solution of Ehrlich reagent (4-dimethylaminobenzaldehyde) in 10% H2SO4 and 10% Triton X-100 gives a colored product, which is detected at 560 nm. The calibration graph is rectilinear in the range 1 to 80 µg mL-1 of I. Optimization experiments are described especially for concentration. of chloramine T (oxidant) and cysteine (color stabilizer). The method, which avoids use of organic solvents, allows 100 samples to be analyzed in ~5 h. Recoveries of I are 94.8 to 103.7%. Results agreed well with those from a batch method.
Hydroxyproline Skin Spectrophotometry

"Determination Of Manganese By Flow Injection Analysis Based On Its Catalytic Effect On The Oxidative Coupling Reaction Of 3-methyl-2-benzothiazolinone Hydrazone With NN-dimethylaniline"
Anal. Sci. 1991 Volume 7, Issue 1 Pages 97-101
Y. MIYATA, T. HIRANO, S. NAKANO and T. KAWASHIMA

Abstract: Sample solution was injected into a carrier stream of aqueous 1.2% H2O2 and reacted at 50°C in a reaction coil (3 m) with 0.1 M citrate - 0.2 M Tris buffer solution (pH 11), 30 mM NN-dimethylaniline - 3 mM 3-methyl-2-benzothiazolinone hydrazone - 3 mM 1,10-phenanthroline. The mixture was cooled to 25°C in a 1-m reaction coil and the absorbance was measured at 590 nm. The calibration graph was rectilinear for 4 to 30 ng mL-1 of Mn and the coefficient of variation were 1.9 to 4.2%. The method was applied in the analysis of standard reference materials, the results obtained compared well with certified values.
Manganese NIES 1 NIES 3 NIES 7 Spectrophotometry

"Determination Of Selenium By Flow-injection Analysis Based On The Selenium(IV)-catalyzed Reduction Of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium Bromide"
Anal. Sci. 1991 Volume 7, Issue 1 Pages 103-107
E. AOYAMA, N. KOBAYASHI, M. SHIBATA, T. NAKAGAWA and H. TANAKA

Abstract: Sample solution was mixed with NaOH (to pH 7) and 0.1 M phosphate buffer solution (pH 7) containing 12 mM bathocuproine disulfate and the mixture was injected into a carrier solution of 0.1 M phosphate buffer solution (0.2 mL min-1) and through a column (5 cm x 4.6 mm) of Chemcasorb 3-ODS-H operated at 40°C. The eluate was mixed with 7.3 mM dithiothreitol and 3-[4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide and the absorbance of the solution was measured at 565 nm. Analysis time was 8 min. The calibration graph was rectilinear for 1.3 pmol to 1.2 nmol Se (IV) and the coefficient of variation was 2.2%. The method was applied in the analysis of lobster refrence material, recovery was 103% for 5 µg mL-1 of Se and no interference was present.
Selenium NRCC TORT-1 Spectrophotometry

"Inline Pre-treatment Method For Flow Injection Analysis Of Total Phosphorus And Nitrogen Impurities In Hydrogen Peroxide Solution"
Anal. Sci. 1991 Volume 7, Issue 2 Pages 347-348
M. AOYAGI, Y. YASUMASA and A. NISHIDA

Abstract: Hydrogen peroxide is catalytically decomposed by use of Pt wire at 100°C, prior to analysis for total N and total P by the flow injection procedures described previously (cf. ibid., 1989, 5, 235, and Anal. Chim. Acta., 1988, 214, 229). For 50 to 150 mg mL-1 of P and N recoveries were 100.1 to 112% and 99.2 to 103.8%, respectively, and coefficient of variation were 0.7% (n = 3). The method is considerably quicker than an offline pre-treatment method used previously (cf. Bunseki Kagaku, 1990, 39, 131).
Nitrogen Phosphorus Inorganic compound Electrode

"Flow Injection Spectrophotometric Determination Of Trace Amounts Of Iodide By Its Catalytic Effect On The 4,4'-bis(dimethylamino)diphenylmethane [4,4'-methylenebis-(NN-dimethylaniline)] - Chloramine T Reaction"
Anal. Sci. 1991 Volume 7, Issue 2 Pages 229-234
N. YONEHARA, S. KOZONO and H. SAKAMOTO

Abstract: Sample solution (300 µL) was injected into a water carrier stream (3 mL min-1) and this was mixed successively with acetate buffer solution (pH 4.5), 1.2 mM 4,4'-methylenebis-(NN-dimethylaniline) in aqueous 0.23% acetic acid, and 0.75 mM chloramine T (all 0.5 mL min-1). The reaction mixture was passed through a 4-m reaction coil at 30°C and then through a flow cell in which the absorbance was monitored at 600 nm. Calibration graphs were rectilinear for up to 2 µg L-1 of I-; the coefficient of variation at 0.4 and 4 µg L-1 were 2.8 and 0.8%, respectively (n = 10). The sampling rate was 85 h-1. Free iodine exhibits a lower catalytic effect, and IO3- has no effect at concentration. 50 µg L-1 (as iodine), but both species can be determined after reduction to I- by treatment with thioacetamide in acid solution The effects of >30 foreign ions are reported. Only ions that participate in redox processes or combine with I- interfere significantly. The method has been applied to various natural waters.
Iodide Environmental Spectrophotometry

"Simultaneous Determination Of Glycosylated Albumin And D-glucose In Human Serum By High Performance Liquid Chromatography With Post-column Fluorescence Derivatization"
Anal. Sci. 1993 Volume 9, Issue 1 Pages 9-14
G.-Q. ZHANG, M. KAI, H. NOHTA, Y. UMEGAE and Y. OHKURA

Abstract: Serum is diluted 100-fold with 10 mM NaH2PO4 and set aside for 5 min, and a 100 µL portion of the solution is injected on to a TSKgel G2000SWXL column (30 cm x 7.8 mm) operated with 0.1 M phosphate buffer (pH 6.7) - 0.1 M Na2SO4 - 80 mM NaN3 as mobile phase (0.7 mL min-1). The eluate is mixed with 15 mM 4-methoxybenzamidine (I) - 0.55 M NaOH or 5 mM meso-1,2-bis-(4-methoxyphenyl)ethylenediamine (II) - 0.25 M NaOH (0.3 mL min-1) and heated in a reaction coil (7 or 20 m x 0.5 mm, respectively) at 95°C or 140°C, respectively. After passage of the eluate through a cooling coil, the fluorescence is monitored at 470 or 460 nm for I or II, respectively (excitation at 310 or 340 nm, respectively), in a 15 µL flow cell, the peak heights being measured. Glycosylated albumin and glucose are well separated; the coefficient of variation at 2.4 and 5.2 µmol mL-1 of the respective analytes were 3.5 and 2.5% (detection limits 100 and 3 pmol) after reaction with I and 2.6 and 3.5% (150 and 5 pmol) after reaction with II, respectively. A method is also described for determination of the reducing carbohydrates liberated from human serum albumin by acid hydrolysis.
Albumin, glycosylated d-Glucose Serum Human HPLC Fluorescence

"Carrier Precipitation And Flotation Of Traces Of Phosphate In Highly Concentrated Sodium Chloride Solutions"
Anal. Sci. 1994 Volume 10, Issue 3 Pages 389-392
T. TANAKA, S. KAYUKAWA and A. MIZUIKE

Abstract: Al (0.5 g) was dissolved in 25 mL of hot 4 M HNO3, diluted to 100 mL with water and portions (2 ml) were mixed with 200 mL of aqueous 30% NaCl. Aqueous 15 M NH3 solution was added dropwise to form a flocculent precipitate, 6 mL of 1 mg/ml sodium oleate and 2 mL of 1 mg/ml sodium dodecylbenzenesulfonate (both in aqueous 70% ethanol) were added and the mixture was transferred to a glass flotation cell (illustrated). N2 was bubbled (2 ml/cm2. min) through the sintered glass disk for 2 min to float the precipitates as a foam. After suction-removal of the mother liquor and aqueous washing, the foam was destroyed with 5 mL of ethanol, the precipitates were dissolved 1 M HNO3 and the filtrate was diluted to 20 mL with 1 M HNO3. Portions (200 µL) were injected into a carrier stream (0.8 ml/min) of 1 M HNO3 which merged with a stream (0.8 ml/min) of 4 mM ammonium molybdate in 0.2 M HNO3/0.5% ascorbic acid in 10% glycerol (1:1) and passed through a reaction coil (10 m x 0.5 mm i.d.; 80°C) to a detector for determination of the phosphomolybdenum-blue complex at 660 nm. The calibration graph was linear for up to 20 µg of phosphate and the detection limit was 8 ng/g. Si and As(V) did not interfere.
Phosphate Metal Spectrophotometry Sample preparation

"Online Pretreatment With Cobalt(III) Ions For A Flow Injection Spectrophotometric Determination Of Organic Phosphorus"
Anal. Sci. 1995 Volume 11, Issue 5 Pages 787-792
H. TANAKA, T. FUKUOKA and K. OKAMOTO

Abstract: Portions (500 µL) of solutions of standard organophosphorus compounds (1 mg/l as P; tabulated) were injected into a carrier stream of water and mixed with a stream of water containing 32 mM Co(III) in a coil (5 m x 1 mm i.d.) containing a Pt wire (3 m x 0.2 mm i.d.). The mixed solution was treated with ammonium molybdate/ascorbic acid reagent injected into the flow system and mixed in a coil (1 m x 1 mm i.d.) at 75°C and the absorbance of the colored product formed was measured at 880 nm. The calibration graph was linear up to 1.5 mg/l of P and the detection limit was 0.005 mg/l. RSD (n = 10) was 3% for 1 mg/l (as P) disodium phenyl phosphate. Average recoveries were ~100% for all the model compounds studied. The method was applied to the determination of P in water samples. Results were in good agreement with those obtained by Official methods except for water samples with high-chloride content (i.e. seawater). Sample throughput of 10^-12/h was achieved by this method.
Phosphorus Sea Spectrophotometry

"Flow Injection Determination Of Hydrogen Peroxide By Bis-(2,4,6-trichlorophenyl)oxalate Chemiluminescence In O/W Emulsion"
Anal. Sci. 1996 Volume 12, Issue 6 Pages 881-885
T. HASEBE, E. HASEGAWA and T. KAWASHIMA

Abstract: A schematic of the FIA manifold is presented. Sample (60 µL) was injected into the water carrier stream (0.6 ml/min) and merged with 0.6 M Tris buffer of pH 9 (0.6 ml/min). The mixture was transferred to a heating coil (3 m length) in a water bath at 37±0.1°C. A 1.5 wt.% Tween 20 solution and a mixture of 0.1 mM bis-(2,4,6-trichlorophenyl)oxalate and 1 mM perylene in ethyl acetate were mixed (0.6 ml/min) to form an oil/water (O/W) type emulsion. The mixture was then pumped (1.2 ml/min) and merged with the carrier stream in front of the flow cell. The light emitted from the chemiluminescence reaction was measured over the range 400-600 nm and was proportional to the H2O2 concentration. The calibration graph was linear from 0.1-1 µM-H2O2. The method was applied to the determination of L-glutamic acid in culture medium as H2O2. Results are discussed.
Hydrogen peroxide Fermentation broth Chemiluminescence

"Simultaneous Flow Injection Determination Of Acetylcholine And Choline Based On Luminol Chemiluminescence In A Micellar System With Online Dialysis"
Anal. Sci. 1997 Volume 13, Issue 1 Pages 93-98
T. HASEBE, J. NAGAO and T. KAWASHIMA

Abstract: The method was based on the determination of H2O2 produced from acetylcholine (I) and choline (II) by enzyme reactions. A flow diagram is given of the FIA system. A water carrier, a 0.02 M disodium hydrogen phosphate/NaOH buffer of pH 11, a 0.02 M phosphate buffer of pH 7, a 1 µM-Co(II) solution in 0.01 M HCl as a catalyst for the chemiluminescence reaction and a mixed solution of 0.5 µM-luminol, 0.1 M sodium hydrogen carbonate and 0.18% SDS in borate buffer solution of pH 11 were pumped by three double-plunger pumps. An 800 µL sample was injected into the carrier, dialysed to remove protein and passed through an anion-exchange column to remove other interferents such as ascorbic acid, uric acid, histidine and tryptophan. II was converted to H2O2 via choline at another immobilized enzyme column. H2O2 produced from II was passed through a delay coil before the chemiluminescence of I and II were measured from 350-650 nm. The reactions were performed at 37°C. The method could determine down to 1 µM at a sampling rate of 6 samples/h.
Acetylcholine Choline Chemiluminescence

"Selective Fluorogenic Flow Injection Procedures For Primary, Secondary, And Tertiary Amines In Nonaqueous Media"
Anal. Proc. 1988 Volume 25, Issue 3 Pages 60-61
I. R. C. Whiteside, P. J. Worsfold, A. Lynes, E. H. McKerrell

Abstract: Three different reagent systems were used with an apparatus that included a 1-m reaction coil operated at 45°C and an LS-2 fluorimetric detector (Perkin-Elmer) with a 7 µL flow cell. For primary amines, phthalaldehyde and 2-mercaptoethanol (both 58 mM) in ethyl acetate were used as reagents, with detection at 431 nm (excitation at 340 nm). For secondary amines, the merged stream after reaction with the same reagents was further blended with 28 mM 7-chloro-4-nitrobenzofurazan in ethyl acetate and passed through a second 1-m coil before detection at 525 nm (excitation at 480 nm). Tertiary amines were determined by reaction with 4% malonic acid in acetic anhydride and detection at 441 nm (excitation at 400 nm). Rectilinear ranges were up to 0.8, 1.5 and 2.5 mM and coefficient of variation were 1.0, 1.3 and 2.1% for hexylamine, dihexylamine and triethylamine, respectively, as test analytes.
Amines, primary Amines, secondary Amines, tertiary Fluorescence

"Development Of An FIA Method With Online Microwave-assisted Saponification Of Vitamin A To Retinol And Direct Inline Spectrophotometric Determination"
Anal. Proc. 1995 Volume 32, Issue 3 Pages 85-89
Encarnaci&oacute;n Luque P&eacute;rez and Stephen J. Haswell

Abstract: Sample (0.3 ml) was injected into a carrier stream of 90% ethanol (2.2 ml/min) and mixed with a stream of 30% KOH (0.55 ml/min). Saponification was carried out in a reactor (250 cm x 0.8 mm i.d.) by heating for 30 s at 127.5 W in a microwave oven. The mixture was then cooled online in an ice-bath prior to online detection at 325 nm. The calibration graph was linear from 0.5-20 ppm vitamin A. The limit of detection was 0.3 mg/l for vitamin A as retinol. The RSD (n = 6) was 1-3.8%. Sample throughput was 120 s.
Vitamin A Spectrophotometry

"Robotic Automation In The Analysis Of Aflatoxins"
Adv. Lab. Autom. Rob. 1991 Volume 7, Issue 1 Pages 303-313
Pieta, L.

Abstract: Peanut butter (25 g) was blended with 125 mL of aqueous 60% methanol for 1 min, the mixture was filtered and a 10 mL portion of the filtrate was mixed with 10 mL of water. The resulting solution was placed in a tube in the sample rack of a Zymate Master Laboratory Station. The system automatically carried out affinity chromatography on an Aflatest-P column with acetone as eluent, evaporation of the eluate under N and reconstitution of the residue in aqueous 23% THF. The solution was then automatically subjected to HPLC on a column of Radial-Pak Phenyl (5 µm), operated at 30°C, with aqueous 23% THF as mobile phase (1.2 mL min-1), post-column derivatization with iodine at 75°C and fluorimetric detection at 400 nm (excitation at 360 nm). The robotic procedure afforded better reproducibility than the corresponding manual procedure. Recoveries were >91%. Samples throughput was 40 day-1.
Aflatoxins Food HPLC Fluorescence

"Amperometric Flow Injection Measurement Of Protein In Dairy Products Using Glutaraldehyde"
Agric. Biol. Chem. 1987 Volume 51, Issue 10 Pages 2835-2836
Hiroyuki UKEDA, Shoko TANAKA, Kiyoshi MATSUMOTO and Yutaka OSAJIMA

Abstract: Protein was determined in dairy produce in a PTFE flow system (illustrated), based on simultaneous injection of glutaraldehyde and sample and then confluence before reaching the Clark O electrode (potential -0.8 V). Reaction was optimum at a glutaraldehyde concentration. of 10% and a reaction temperature of 30°C. The flow rate affected the rectilinear range and the slope of the calibration graph. Response was rectilinear from 1.0 to 4.0% of protein at 0.95 mL min-1, when 12 samples could be analyzed in 1 h. The limit of detection was 2 mM for L-glycine and 0.3% for nutrose (a Na salt of casein).
Protein Dairy Products Amperometry Electrode

"Analysis Of Pentoses In Dry Wine By High Performance Liquid Chromatography With Post-column Derivatization"
Am. J. Enol. Vitic. 1986 Volume 37, Issue 4 Pages 269-274
Bruce D. Franta, Leonard R. Mattick, and John W. Sherbon

Abstract: Wine samples were adjusted to pH 8 to 9 with concentrated aqueous NH3 and diluted with water before separation of the pentoses on an HPX-87P lead cation-exchange column (30 cm x 7.8 mm), at 70°C, fitted with an Aminex HPX-87C carbohydrate pre-column. Post-column derivatization with tetrazolium blue(I) was achieved with a reagent solution containing 80% ethanol - 0.01 M NaOH - 0.1% I at 1.1 mL min-1 and a 1.8-m reaction coil at 85°; detection was at 520 nm. The rectilinear ranges for xylose, arabinose, ribose, glucose and rhamnose extended up to 2.4 µg (that for fructose up to 1.2 µg), coefficient of variation were ~2% and detection limits were <0.3 µg. The method was only applicable to dry wines as large glucose concentration. (e.g., in sweet wines) affected the determination of xylose.
Pentoses