University of North Florida
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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

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Urine

Classification: Biological fluid -> urine

Citations 272

"Flow Injection Analysis-amperometric Determination Of Ascorbic And Uric Acids In Urine Using Arrays Of Gold Microelectrodes Modified By Electrodeposition Of Palladium"
Anal. Chim. Acta 2000 Volume 404, Issue 1 Pages 151-157
Renato C. Matos, Márcio A. Augelli, Claudimir L. Lago and Lúcio Angnes

Abstract: Uric acid (UA) and ascorbic acid (AA) present in urine were rapidly-determined by the amperometric method in association with flow injection analysis. An array of gold microelectrodes modified by electrochemical deposition of palladium was employed as the working electrode. Uric and ascorbic acids were quantified in urine using amperometric differential measurements at +0.75 and +0.55 V, respectively. This method is based on three steps involving the flow injection of: (1) the sample spiked with a standard solution, (2) the pure sample, and (3) the enzymatically treated sample. The enzymatic treatment was carried out with ascorbate oxidase, uricase, and peroxidase at pH 7. The calibration curves for freshly prepared ascorbic and uric acid standards were very linear in the concentration ranges of 0.44-2.64 mg L-1 (AA) and of 0.34-1.68 mg L-1 (UA) with a relative standard deviation (RSD) <1 %. For uric acid, the real sample analyzes where compared with the classical spectrophotometric method, showing deviations between 3.1 and 8.6% (n = 9).
Ascorbic acid Uric acid Amperometry Electrode Electrode Method comparison Optimization

"Determination Of Hemoglobin Based On Its Enzymatic Activity For The Oxidation Of O-phenylenediamine With Hydrogen Peroxide"
Anal. Chim. Acta 2000 Volume 413, Issue 1-2 Pages 109-113
Ke Zhang, Ruxiu Cai, Danhua Chen and Luyuan Mao

Abstract: A new method has been developed for the determination of hemoglobin (Hb) based on its enzymatic activity for the oxidation of o-phenylenediamine with hydrogen peroxide. Stopped-flow spectrophotometry was used to study the kinetic behavior of the oxidation reaction. The absorbance of the reaction product, 2,3-diaminophenazine, at the wavelength of 425 nm was recorded every millisecond during the first 0.2 min of the reaction. The initial reaction rate obtained at 48°C was proportional to the concentration of Hb in the range of 8.5 x 10^-56.5 x 10^-11 mol/l. Excess of bovine serum albumin, Ca(II), Mg(II), Cu(II) and glucose did not interfere. The relative standard deviations were within 5% for the determination of different concentrations of Hb. The detection limit was found to be 3.2 x 10^-12 mol/l.
Hemoglobin Spectrophotometry Stopped-flow Interferences Kinetic Optimization Indirect

"Chemiluminometric Behaviour Of Erythromycin And Related Compounds"
Anal. Chim. Acta 2000 Volume 410, Issue 1-2 Pages 153-157
Anastassia Mitsana-Papazoglou, Argyro Fragaki, Paraskevi Chamosfakidi and Antony C. Calokerinos

Abstract: This paper reports the chemiluminescence generated from erythromycin and other macrolide antibiotics by the action of cerium(IV) in perchloric acid or potassium permanganate in sulphuric acid or polyphosphoric acid with limits of detection (3 x noise) for erythromycin in the range 0.15-0.31 µg mL-1. Permanganate in polyphosphoric acid gives the greatest sensitivity. A preliminary investigation of the reaction mechanism is also presented.
Erythromycin Chemiluminescence

"Matrix Effect Modelling In Multivariate Determination Of Priority Pollutant Chlorophenols In Urine Samples"
Anal. Chim. Acta 1999 Volume 381, Issue 1 Pages 93-102
F. Navarro-Villoslada, L. V. P&eacute;rez-Arribas, M. E. Le&oacute;n-Gonz&aacute;lez and L. M. Polo-D&iacute;ez

Abstract: The possibility of modelling matrix effect in multivariate calibration has been studied for a complex sample such as urine. The matrix effect was minimized by including, in the calibration step, standard samples containing the analytes in the presence of the interfering matrix. The number of samples was selected taking into account the standard error of prediction (SEP). By this method, a flow injection multivariate spectrophotometric determination of five priority pollutant chlorophenols in urine samples using a PLS method is demonstrated. The recoveries of the chlorophenols in natural urine samples ranged from 85±32% to 121±31% for concentrations between 0.2 and 1.0 mg L-1. Net analyte signal calculation was used to estimate the selectivity of the signal for each chlorophenol. Selectivity was found to range between 0% and 2.5% of the measured signal.
Chlorophenols Spectrophotometry Multivariate calibration Partial least squares Multicomponent Interferences

"Surface Improvement Of Glassy Carbon Electrode Anodized In Triethylene Glycol And Its Application To Electrochemical HPLC Analysis Of Protein-containing Samples"
Anal. Sci. 2000 Volume 16, Issue 3 Pages 293-298
Hatsuo MAEDA, Kazunori KATAYAMA, Rie MATSUI, Yuji YAMAUCHI and Hidenobu OHMORI

Abstract: order to improve electrochemical performance of a glassy carbon (GC) electrode anodized in triethylene glycol (TEG), a GC electrode was anodized in water prior to TEG anodization. The effect of this pretreatment was evaluated by comparing electrochemical responses of acetaminophen on HPLC using the following electrodes: a GC electrode anodized in both water and TEG (double modified GC electrode); an unmodified GC electrode; GC electrodes anodized in either water or TEG. HPLC was carried out for samples containing uric acid and acetaminophen with or without various proteins. The results reveal that the double modified GC electrode has satisfactory sensitivity, reproducibility, and durability in electrochemical detection of acetaminophen by HPLC, compared with ether electrodes. In order to demonstrate the advantage of the double modified GC electrode, analysis of acetaminophen from a urine sample was performed by HPLC without carrying out any tedious procedures such as the removal of proteins. In addition, electrochemical analyzes of various compounds were performed using the double modified GC electrode in a near-flow injection mode, suggesting that the electrode has potential applications for HPLC analysis of biologically important cationic and neutral compounds.
Protein Electrode Detector

"Plant Tissue-based Chemiluminescence Flow Biosensor For Urea"
Anal. Chim. Acta 2000 Volume 407, Issue 1-2 Pages 81-86
Wei Qin, Zhujun Zhang and Youyuan Peng

Abstract: A novel plant tissue-based chemiluminescence (CL) biosensor for urea combined with flow injection analysis is proposed in this paper. The analytical reagents involved in the CL reaction, including luminol and permanganate, were both immobilized on anion exchange resin columns, while the biological material soybean tissue was packed in a mini-glass column. By the urease-catalyzed reaction in the plant tissue column, urea was hydrolyzed to NH4+ and HCO3-. The anion produced could release luminol from the anion-exchange column with immobilized luminol, which then reacted with permanganate eluted from the anion-exchange permaganate column with sodium hydroxide, thus producing a CL signal. The CL emission intensity was linear with urea concentration in the range 4-400 µM; the detection limit was 2 µM. Interfering ions co-existing in urine could be effectively separated on-line by an ion-exchange column placed upstream. The biosensor was applied successfully to the analysis of urea in urine samples.
Urea Sensor Immobilized reagent Resin Column Solid phase reagent Indirect

"Photochemical-reaction Detectors In Continuous-flow Systems: Applications To Pharmaceuticals"
Anal. Chim. Acta 1980 Volume 114, Issue 1 Pages 137-146
A. H. M. T. Scholten, U. A. Th. Brinkman and R. W. Frei

Abstract: Several basic parameters of a photochemical reactor coupled to a high-performance liquid Chromatographie system are discussed. The non-fluorescent clobazam and desmethylclobazam and three phenothiazines, which exhibit native fluorescence, are used as model compounds. On irradiation with ultra-violet light, the reaction products formed display fluorescence (clobazam, desmethylclobazam) or unproved fluorescence characteristics (phenothiazines). The effects of carrier stream (mobile-phase) composition, time of irradiation and band broadening in the reactor on the fluorescence signal are described. The polarity of the organic solvents used (methanol, ethanol, acetonitrile) appears to have an important effect on the fluorescence intensity. For clobazam and desmethylclobazam, detection limits of 70 and 120 pg, respectively, were calculated after an irradiation time of 28 s with methanol-0.01 M (pH 5) acetate buffer (1:1) as mobile phase. The method is applied to the determination of both compounds in serum and urine samples.
Clobazam Desmethylclobazam Phenothiazines Chromatography Fluorescence Photochemistry

"Direct Spectrophotometric Determination Of Thiocyanate In Serum And Urine With A Continuous-flow Analyser"
Anal. Chim. Acta 1981 Volume 128, Issue 1 Pages 169-175
Gianfranco Giraudi, Caterina Grillo

Abstract: A spectrophotometric method for the rapid measurement of thiocyanate in serum and urine without separation from interfering substances is described. Thiocyanate reacts immediately with chloramine-T in presence of iron(III) chloride catalyst to give cyanogen chloride, which reacts with a mixture of -picoline (4-methylpyridine) and barbituric acid to form a soluble violet-blue product, which is measured at 605 nm. Other components of physiological fluids react more slowly and do not interfere if the reaction time of the chlorinating step is kept very short. The proposed procedure is compared with a highly selective method, based on the oxidation of thiocyanate to cyanide, and good agreement was obtained for both serum and urine. The method is readily adapted to a continuous-flow procedure with a Technicon AutoAnalyzer.
Thiocyanate ion Spectrophotometry

"Flow Potentiometric Stripping Analysis For Mercury(II) In Urine, Sediment And Acid Digest Of Biological Material"
Anal. Chim. Acta 1982 Volume 141, Issue 1 Pages 157-162
Daniel Jagner and Kerstin &Aring;r&eacute;n

Abstract: In flow potentiometric stripping analysis for mercury in urine, the samples are acidified with concentrated nitric acid and heated to boiling for 10 min. After cooling, the samples are buffered by the addition of concentrated ammonia and then pre-electrolysed at a gold working electrode for 90 s at -0.25 V vs. SCE at a flow rate of 1.75 mL min-1. The stripping solution is 1 M sodium bromide solution acidified with 0.1 M hydrochloric acid and containing chromium(VI). The detection limit at one σ level is 0.05 µM. Orchard leaves, sediment and fish muscles are digested in nitric acid at 140°C for 30 min prior to buffering with ammonia and potentiometric stripping analysis for 200 s at -0.20 V vs. SCE at a flow rate of 1.75 mL min-1.
Mercury(II) Clinical analysis Potentiometric stripping analysis Sample preparation

"Performance And Characteristics Of The Fluoride-selective Electrode In A Flow Injection System"
Anal. Chim. Acta 1983 Volume 145, Issue 1 Pages 207-212
P. Van Den Winkel and G. De Backer, M. Vandeputte, N. Mertens, L. Dryon and D. L. Massart

Abstract: A simple, inexpensive home-made timer for coupling cam-controlled samplers to injectors for flow injection analysis is presented. Experimental conditions and a flow diagram are described for the determination of fluoride by means of a fluoride-selective electrode in the concentration range 0.3-10 ppm, with a sample rate up to 120 hr-1.
Fluoride Electrode Apparatus

"Determination Of Cadmium In Human Urine By Extraction With Dithizone In A Flow Injection System"
Anal. Chim. Acta 1983 Volume 153, Issue 1 Pages 207-212
J. L. Burguera and M. Burguera

Abstract: Urine (90 µL) is injected into a flowing stream (0.8 mL min-1) of 3 mM hydroxylamine - 5 mM K Na tartrate - 10 mM K4Fe(CN)6 - 10 mM tartaric acid (pH 10.5) that is subsequently mixed with 39 µM-dithizone in CHCl3 (0.8 mL min-1). The mixture is passed to a phase separator (described, with a diagram), and the absorbance of the organic phase is measured at 518 nm. Calibration graphs are rectilinear for up to 12 ng mL-1 of Cd and the limit of detection is ~0.2 ng mL-1. Recoveries of 91 to 113% were obtained and the coefficient of variation (n = 5) for 0.5 to 5 ng mL-1 was 2 or 3%. For 0.7 ng mL-1 of Cd there is no interference from 1 ng mL-1 of Co, Fe, Ni, Pb or Zn. Results agree well with those obtained by AAS
Cadmium Clinical analysis Spectrophotometry Sample preparation Interferences Method comparison Solvent extraction Phase separator Dithizone

"Indirect Atomic Absorption Spectrometric Determination Of Perchlorate By Liquid-liquid Extraction In A Flow Injection System"
Anal. Chim. Acta 1985 Volume 169, Issue 1 Pages 161-169
M. Gallego and M. Valc&aacute;rcel

Abstract: Serum or urine samples were centrifuged and the supernatant solution were subjected to flow injection analysis. The sample was mixed with the carrier solution [acetate buffer solution (pH 4.75) that was 4.8 mM in ascorbic acid and contained 8 µg mL-1 of Cu] and the mixture was extracted with 0.2% 6-methylpicolinaldehyde azine solution in isobutyl methyl ketone. The extract was mixed with water and analyzed by AAS The calibration graph was rectilinear for 0.1 to 5.0 µg mL-1 of ClO4- and the detection limit was 70 ng mL-1. Recovery was 98.5 to 107% and the coefficient of variation was 0.7%.
Perchlorate Spectrophotometry Sample preparation Extraction Tecator Indirect

"Voltammetric Determination Of Doxorubicin In Urine By Adsorptive Preconcentration And Flow Injection Analysis"
Anal. Chim. Acta 1985 Volume 176, Issue 1 Pages 105-112
Edward N. Chaney, Jr. and Richard P. Baldwin

Abstract: A flow injection system has been applied to the earlier manual procedure (Anal. Chem., 1982, 54, 2556). The sample (6 µL) is injected into a carrier stream (0.1 mL min-1) of 0.2 M acetate buffer (pH 4.5) and passed into a detector cell equipped with a thin-layer carbon-paste working electrode (area 0.071 cm2) and a silver - AgCl reference electrode. A potential of +0.3 V is applied to the carbon-paste electrode until a stable response is obtained. Then the potential is scanned from +0.3 to +0.7 V in the differential pulse mode at 2 or 5 mV s-1. The height of the oxidation peak at +0.57 V is rectilinearly related to concentration. in the range 1 to 1000 nM-I. In order to overcome variable matrix effects in urine samples, the method of standard additions is used for quantitation. The flow injection procedure gives better discrimination against adsorbable sample components (e.g., uric acid) than the manual technique.
Doxorubicin Electrode Voltammetry Preconcentration Standard additions calibration

"Determination Of Lead In The Urine Of Exposed And Unexposed Adults By Extraction And Flow Injection/atomic Absorption Spectrometry"
Anal. Chim. Acta 1986 Volume 186, Issue 1 Pages 273-277
Jos&eacute; Luis Burguera and Marcela Burguera, Luis La Cruz O and Olga Raquel Naranjo

Abstract: Lead is extracted from urine with ammonium pyrrolidine-1-carbodithioate into isobutyl methyl ketone, and the extract is analyzed by flow injection AAS, by injection into the water carrier stream (flow rate 3.8 mL min-1). The calibration graphs are rectilinear over the range 15 to 200 µg l-1. The detection limit is 10 µg l-1, recoveries are 96 to 105%, and coefficient of variation are 5% (within- and between-day; n = 10 and n = 30, respectively). Results agree well with those obtained by spectrophotometry.
Lead Clinical analysis Spectrophotometry Sample preparation Extraction Method comparison

"Bipolar Pulse Conductometric Detection Of Enzyme Reactions In Flow Injection Systems. Urea In Serum And Urine"
Anal. Chim. Acta 1986 Volume 186, Issue 1 Pages 91-100
Douglas Taylor and Timothy A. Nieman

Abstract: Urea(I) is determined by enzymatic hydrolysis on a column (5.7 cm x 3.2 mm) of urease bound to controlled-pore glass, with phosphate buffer (pH 7.3) as the carrier stream (20 mM for urine and 2 mM for serum samples) containing NaCl; the reaction is monitored by measuring conductivity before and after hydrolysis, with automatic processing to give a differential signal. The calibration graph is rectilinear for 10 mM I, with detection limits of 0.1 mM I in urine and 0.01 mM I in serum; the coefficient of variation is 3%. The sampling rate is 20 h-1. The accuracy compares well with that of existing methods.
Urea Clinical analysis Conductometry Controlled pore glass Immobilized enzyme

"Fluoride Ion-selective Electrode In Flow Injection Analysis. 3. Applications"
Anal. Chim. Acta 1986 Volume 188, Issue 1 Pages 151-164
Wolfgang Frenzel and Peter Br&auml;tter

Abstract: Optimum conditions are described for the determination of trace amounts of F- in tap water, beverages and urine by flow injection potentiometry with a F--selective electrode. Good sensitivity (1 µg l-1) and long-term stability were obtained, with a sample throughput of 30 to 40 h-1, based on triplicate injections at 120 h-1. Total ionic strength adjustment buffer (TISAB-III) was unsuitable for the analysis of undiluted tea and urine. Such samples with high inherent I and large amounts of interfering elements required a modified citrate-containing TISAB buffer. Recoveries of 0.01 to 1 mg L-1 of F- added to tap water, tea and urine were 91 to 106%. The apparatus allowed rapid changes between buffers and carrier streams.
Fluoride Electrode Potentiometry Interferences

"Fluorimetric Determination Of Danthron In Pharmaceutical Tablets And In Urine"
Anal. Chim. Acta 1987 Volume 192, Issue 2 Pages 293-299
Blair E. Miller and Neil D. Danielson

Abstract: A flow injection system used for determination of danthron(I) in pharmaceutical samples was composed of a loop injector (30 µL) and a 150-cm mixing coil containing 90 mM Na2S2O4 in methanol - aqueous 2% Na2B4O7 (1:1) as carrier (1.2 mL min-1). A spectrofluorimeter fitted with a 3.5 µL flow cell was used to monitor emission at 510 nm (excitation at 388 nm). Rectilinear calibrations were achieved from <0.1 to 30 µg mL-1 of I with a detection limit of 0.01 µg mL-1. Urine samples required pre-separation by HPLC in a 5 µm C1 silica column (25 cm x 4.5 mm) with aqueous 70% methanol as mobile phase (1.2 mL min-1). The eluate was mixed with the carrier of the flow injection system (0.4 mL min-1). A rectilinear calibration graph was obtained for 0.02 to 2 µg mL-1 of I, with a detection limit of 6 ng mL-1.
Danthron HPLC Fluorescence

"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 Electrode Electrode Dialysis Enzyme Heated reaction Interferences Method comparison Reactor

"Simultaneous Determination Of Mercury(II), Copper(III) And Bismuth(III) In Urine By Flow Constant-current Stripping Analysis With A Gold Fiber Electrode"
Anal. Chim. Acta 1987 Volume 202, Issue 1 Pages 117-122
Huang Huiliang, Daniel Jagner and Lars Renman

Abstract: Urine samples are treated with concentrated nitric acid and potassium permanganate ar 70°C for 10 min prior to injection. The flow electrode system consists of a 10 µm diameter gold fiber working electrode, a glassy carbon reference electrode and a platinum counter electrode. In the fully automated constant-current stripping procedure, the gold fiber is first covered with a fresh gold film after which the sample is electrolyzed for 1 min prior to stripping in 0.1 M hydrochloric acid with a current of 0.1 µA. The procedure is repeated on a spiked sample after which the sample analyte concentrations are evaluated and presented digitally and graphically on a printer/plotter. The results obtained for bismuth, copper and mercury in a urine reference sample were 36.9, 39.7 and 47.7 µg L-1 with standard deviations (n=10) of 3.2, 4.2 and 2.1, respectively. The certified values for copper and mercury were 45 and 51 µg l-1; no certified value was available for bismuth.
Bismuth(3+) Copper(3+) Mercury(II) Amperometry Electrode Simultaneous analysis

"Automated Flow Injection Determination Of Sulfonamides By The Bratton-Marshall Reaction For Clinical Analysis, Assays And Dissolution Studies Of Formulation"
Anal. Chim. Acta 1988 Volume 204, Issue 1-2 Pages 271-283
M. A. Koupparis and P. I. Anagnostopoulou

Abstract: Two flow injection manifolds are described based on the Bratton - Marshall reaction, one for 2 to 20 mg L-1 of sulfonamide and the other for 0.5 to 5 mM. N-(1-Naphthyl)ethylenediammonium chloride is used as chromogenic reagent with detection at 545 nm. The method was used in the determination of sulfonamides in serum, urine, feeds and formulations, and for automated dissolution studies of tablets. The detection limit was 0.6 to 1.1 mg l-1, and the coefficient of variation was <0.5% (n = 10). The analysis rate was 72 samples h-1. The pseudo-titrimetric method gave a 1.3% mean difference from the HPLC technique.
Sulfonamides Clinical analysis Spectrophotometry Dissolution rate Method comparison Chromogenic reagent

"Bioluminescence Flow System For Determination Of Branched Chain L-amino Acids In Serum And Urine"
Anal. Chim. Acta 1988 Volume 205, Issue 1-2 Pages 229-237
S. Girotti, A. Roda, M. A. Angellotti and S. Ghini, G. Carrea and R. Bovara, S. Piazzi and R. Merighi

Abstract: Deproteinized urine was centrifuged at 1000 g, the supernatant liquid was filtered (0.45 µm), and the filtrate was diluted 10 to 100-fold with 0.11 M Na4P2O7 buffer of pH 9.0. Serum samples were filtered and diluted with the same buffer. A 10 µL portion of the test sample was injected into an air stream which was mixed with a reagent stream containing NAD+ in the buffer solution and fed through a 1-m reaction coil containing immobilized leucine dehydrogenase, whereupon branched-chain L-amino-acids (L-leucine, L-valine and L-isoleucine) were oxidized to the corresponding 2-oxo-acids, with the formation of NADH. The product was mixed with 10 µM-flavine mononucleotide - 27 µM-decanol - 0.5 mM dithiothreitol in 0.1 M potassium phosphate buffer (pH 6.9) and fed into a second reaction coil where NADH was oxidized in the presence of immobilized NADH oxidoreductase (FMN) and alkanal mono-oxygenase (FMN-linked) and the luminescence was measured. Calibration graphs were rectilinear for 20 to 2000 pmol of acid; the limit of detection was 5 pmol. Within- and between-assay coefficient of variation (n = 10) were 7% and 9.7%, respectively, and recovery was 85 to 116%. Other amino-acids and branched-chain 2-oxo-acids did not interfere. Results for 41 serum samples correlated well with those obtained by ion-exchange chromatography.
Amino acids, L l-Isoleucine l-Leucine l-Valine Bioluminescence Immobilized enzyme Indirect Interferences Method comparison

"Determination Of Ammonium Ion In A Flow Injection System With A Gas Diffusion Membrane. Selection Of Optimal Conditions For The PH Indicator"
Anal. Chim. Acta 1988 Volume 208, Issue 1-2 Pages 81-90
Ryuji Nakata, Takayoshi Kawamura, Hiroyuki Sakashita and Akihiko Nitta

Abstract: Optimum conditions were determined for the spectrophotometric determination of NH4+ by flow injection analysis. A membrane-separation module was constructed from a PTFE membrane filter (80 µm thick; pore size 0.5 µm) tightly held between two PVC sheets acting as spacers, and contained between two clear acrylic plates. The donor solution used was 1 M NaOH. Portions of acceptor stock solution of bromocresol purple(I), bromothymol blue or cresol red, containing NH4Cl buffer if necessary and the pH being adjusted with NaOH, were deaerated to remove CO2 and then injected by using a Rheodyne PTFE rotary valve (type 50) with a loop volume of 132 µL. Maximum sensitivity was achieved by using 15 µM-I at pH 6.8 with a flow rate of 1.0 mL min-1. The effects of donor and acceptor flow rates and of ultrasonic radiation were investigated. A lowering of sensitivity allowed analysis of undiluted urine samples, with a sample rate of 60 h-1 for concentration. >10 µM, and 30 to 40 h-1 for concentration. of 0.3 to 10 µM. The method was more precise than that involving indophenol blue - thymol for the determination of NH4+ in rain and river water.
Ammonium Spectrophotometry Gas diffusion Optimization Phase separator Teflon membrane Ultrasound

"Metalloporphyrin Chemically Modified Glassy Carbon Electrodes As Catalytic Voltammetric Sensors"
Anal. Chim. Acta 1989 Volume 217, Issue 2 Pages 343-351
Joseph Wang and Teresa Golden

Abstract: For many biologically important compounds, heterogeneous charge-transfer rates are very slow at vitreous-carbon electrodes, leading to poorly defined voltammetric response. Metalloporphyrin-coated vitreous-carbon electrodes, however, decreased the potential required for the oxidation of ascorbic acid (I), penicillamine, paracetamol (II), NADH, hydralazine, adrenaline, cysteine and oxalic acid by several hundred mV. The faster rates of electron transfer resulted in a well-defined voltammetric response and increased sensitivity and selectivity. The differential pulse peaks for caffeic acid, I, II and dopamine were enhanced 18-, 10.5-, 9.4- and 8.4-fold, respectively. The coated electrode could be used for amperometric monitoring in flow injection systems and greatly facilitated analysis of urine.
Caffeic acid Dopamine Acetaminophen Ascorbic acid Electrode Voltammetry Sensor Sensitivity Selectivity

"Spectrophotometric Flow Injection Determination Of Urea In Body Fluids By Using An Immobilized Urease Reactor"
Anal. Chim. Acta 1989 Volume 218, Issue 1 Pages 151-155
Petr Solich, Miroslav Pol&aacute;ek and Rolf Karl&iacute;ek, Olga Valentov&aacute; and Miroslav Marek

Abstract: Urease was immobilized on poly(glycidyl methacrylate)-coated controlled-porosity glass which was then packed into PTFE tubing. The reactor was incorporated into a flow system for determination of urea. Serum was diluted 1:50 and urine 1:1000 or 1:2000 with water before injection into 0.2 M phosphate buffer (pH 6.9) containing 2 mM Na2 EDTA, 1 mM NaN3 and 5 µM-2-mercaptoethanol. The solution passed to the enzyme reactor before being mixed with 0.37 M Na salicylate - 4 mM Na nitroprusside - 0.25 M NaOH in aqueous 30% ethanol, and then with 30 mM NaClO and passing to a reaction coil (1.5 m x 0.5 mm) at 50°C. The absorbance of the solution was measured at 700 nm. The calibration graph was rectilinear for 25 to 500 µM-urea, and the coefficient of variation (n = 10) for 300 µM-urea was 1.1%.
Urea Spectrophotometry Buffer Immobilized enzyme Controlled pore glass

"Indirect Flow Injection Determination Of Methadone By Atomic Absorption Spectrometry"
Anal. Chim. Acta 1990 Volume 234, Issue 2 Pages 433-437
R. Montero, M. Gallego and M. Valc&aacute;rcel

Abstract: Methadone (I) is determined in tablets and urine in the presence of other drugs after reduction on a Cd or Zn micro-column and flame AAS detection of the metal ions released. For urine, a 5 mL sample is made alkaline with NaOH and extracted with CH2Cl2. The residue from evaporation of the extract, is dissolved in water, and the solution is adjusted to pH 4.0 with 0.01 M acetic acid. Crushed tablet (200 mg) is dissolved in water by shaking for 55 min and filtering. The final solution (90 µL), at pH 3.3 to 4.3, is injected into a carrier stream of water (3.0 mL min-1) which proceeds to the reduction column (8.5 cm x 1.8 mm) and subsequently to the spectrometer. The calibration graph is rectilinear from 5 to 50 ng mL-1 of I. Recoveries from either column are quantitative, and coefficient of variation in urine (n = 3) are 1.2 to 3.0%. Sampling frequency is 150 h-1, and other drugs do not interfere.
Methadone Spectrophotometry Sample preparation Column pH Calibration Interferences Extraction Indirect Reduction column

"Segmental Flow Injection Analysis: Device And Applications"
Anal. Chim. Acta 1990 Volume 238, Issue 1 Pages 183-190
Li-Ching Tian, Xiao-Ping Sun, Yi-Yun Xu and Zheng-Liang Zhi

Abstract: The cited system possesses features of both flow injection and continuous-flow analysis. The sample zone is segmented by only two air bubbles and contained a valve designed so that sample and bubbles could be quantitatively injected into the carrier stream. The system provided residence times of >10 min at temperature up to 95°C without loss of peak height or sampling frequency, and owing to good reproducibility, analysis could be carried out before the equilibrium state was reached. The method was demonstrated by the determination of amino-acids in tea with the ninhydrin reagent, giving recoveries from 97 to 106%, a limit of detection of 5 mg L-1 and a coefficient of variation (n = 3) of 2.8%. Other applications included determination of ammonium and V in water, Cu in ores and creatine in urine.
Ammonium Vanadium Copper Creatine Detection limit

"Kinetic - Enzymic Determination Of Oxalate In Urine By Flow Injection Analysis With Double Stopped-flow"
Anal. Chim. Acta 1991 Volume 242, Issue 2 Pages 179-183
Juan A. Infantes, Mar&iacute;a Dolores Luque de Castro and Miguel Valc&aacute;rcel

Abstract: The method involved injection of a sample (acidified and filtered) into NAD+ solution in citrate buffer (pH 3.2). The flow was stopped with the sample plug in a reactor containing oxalate decarboxylase immobilized on glass. After 3 min, flow was re-started and the carrier was merged with formate dehydrogenase solution in phosphate buffer (pH 9.5). When the sample plug reached a flow cell, flow was again halted, and the absorbance at 340 nm was measured vs. time for 60 to 240 s. Calibration graphs were rectilinear for 0.1 to 3 mM oxalate. The coefficient of variation (n = 3) were 2.1 to 5.1%, and recovery was 94 to 105.5%. Sensitivity increased with increased measuring time, but the sampling rate fell from 20 to 12 samples h-1.
Oxalate Buffer Glass Immobilized enzyme Kinetic Quenching Stopped-flow

"Spectrofluorimetric Determination Of Diquat By Manual And Flow Injection Methods"
Anal. Chim. Acta 1991 Volume 244, Issue 1 Pages 99-104
T. P&eacute;rez-Ruiz, C. Mart&iacute;nez-Lozano and V. Tom&aacute;s

Abstract: In the manual method, sample solution, containing 0.03 to 9 µg of diquat (I), was mixed with 2 mL of 0.5 M borax buffer (pH 8), 1 mL of 0.5% sodium dithionite and water to 10 mL and, after 5 min, the resulting stable radical of I was detected fluorimetrically at 497 nm (excitation at 428 nm). The method was also adapted for use in a flow injection procedure (diagram of apparatus and details given. The calibration graph was rectilinear from 3 to 900 and 18 to 4000 µg L-1 of I by the manual and flow injection methods, respectively; the detection limit by the manual method was 0.4 µg L-1 and coefficient of variation were 2%. The method was applied in the determination of I in commercial herbicide formulations, water, potatoes, flowers and soil (sample prep. described) and in serum and urine directly with use of a standard additions method.
Diquat Fluorescence Buffer Standard additions calibration

"Online Preconcentration And Determination Of Trace Elements By Flow Injection Inductively Coupled Plasma Atomic-emission Spectrometry"
Anal. Chim. Acta 1991 Volume 248, Issue 1 Pages 241-249
S. Caroli, A. Alimonti and F. Petrucci, Zs. Horv&aacute;th

Abstract: Columns (5 cm x 2 mm) of iminodiacetic acid - ethylcellulose chelating resin (I; 100 to 200 mesh) were used to pre-concentrate trace elements in a computer-assisted online flow injection analysis - ICP-AES technique. Elements of clinical and environmental importance (Cd, Co, Cu and Pb) in water, seawater and urine were determined. A 4-way rotary valve assembly was used to fill the column with solution (mixed with 2 M acetate buffer, pH 5.5), elute the analytes with 2 M HNO3, push the eluent plug with a countercurrent flow of water carrier to the excitation source and wash the column. Sample throughput was 10 to 12 h-1. Compared with pre-concentration. on carboxymethylated polyethyleneimine - polymethylenephenylene isocyanate and Chelex 100 resins, the online mode using I gave a 2- to 4-fold improvement in detection limits and a reduced column volume of about a fifth. Detection power is improved at least one order of magnitude for Cd and Pb in seawater.
Cadmium Cobalt Copper Lead Spectrophotometry Column Preconcentration Chelex

"Rapid Screening Of Porphyrins Using Flow Injection Analysis And Visible Laser Fluorimetry"
Anal. Chim. Acta 1991 Volume 254, Issue 1-2 Pages 189-196
Carmen W. Huie, Joseph H. Aiken and William R. Williams

Abstract: Urine and serum were diluted with 0.15 M hexadecyltrimethylammonium bromide in 0.01 M NaH2PO4 buffer, pH 7.4, and the solution were injected into a carrier stream of the same buffer. The fluorescence of the compounds was measured at ~620 nm with excitation at 488 nm provided by an Ar laser. Urine spiked with 0.02, 0.04 and 0.06 µmM was clearly distinguishable from the blank, these concentration. representing the lower range for abnormal urine. With serum the limit of detection was ~0.015 µM.
Porphyrins Fluorescence Buffer pH

"Determination Of Mitozantrone Using Phase-selective A.c. Adsorptive Stripping Voltammetry In A Flow System With Selectivity Enhancement"
Anal. Chim. Acta 1992 Volume 256, Issue 2 Pages 231-236
Juan Carlos Cortina Villar, Agustin Costa Garc&iacute;a and Paulino Tu&ntilde;on Blanco*

Abstract: Urine was diluted 1:20 to contain standard additions of 25 nM-, 50 nM- and 75 nM-mitozantrone (final concentration.), and 0.1 mL portions of these solution were injected into a carrier stream of 0.1 M HClO4 (pH 1.12; 1.5 mL min-1). The mitozantrone became adsorbed on a carbon-paste electrode (prep. described), from which it was stripped by a.c. voltammetry. For 1 µM-mitozantrone in urine, the value obtained was 0.985 µM with a coefficient of variation (n = 5) of 3.7%. A flow cell incorporating a stationary carbon paste electrode coupled with a.c. voltammetry was used. Preconcentration. and determination of the cancer chemotherapy drug mitoxanthrone (I) were achieved via a flow injection approach utilizing adsorption of the drug on the electrode, followed by medium exchange and a.c. voltammetry on the adsorbed surface. A linear response was obtained in the concentration. range 5 x 10^-9-1.5 x 10^-7 M with aqueous samples. The method was used for the determination of I in urine without any sample pretreatment; the relative standard deviation obtained was 1.1% (n = 5) with a concentration. of 1 x 10^-6M. The proposed method is more selective than other methods suggested for the determination of I in urine and plasma samples, which usually require some kind of sample pretreatment.
Mitozantrone Voltammetry Selectivity Method comparison Standard additions calibration

"Online Microwave Sample Pre-treatment For The Determination Of Mercury In Water And Urine By Flow Injection Cold Vapor Atomic Absorption Spectrometry"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 91-103
Bernhard Welz*, Dimiter L. Tsalev and Michael Sperling

Abstract: Conditions yielding high recoveries of Hg from inorganic and organic Hg compounds (used in method development) and urine were developed for use with a system incorporating an auto-sampler, a microwave digester, a hydride system, an amalgamation accessory and an AAS instrument. Samples were mixed offline with 1% (v/v) of aqueous stabilizer solution [0.5% of K2Cr2O7 in HNO3 (1:1)] and, in the autosampler vessels, with 1 to 2% (v/v) of bromination reagent (aqueous 2.23% KBrO3 - 8% KBr) before introduction into a carrier stream of 0.3% HCl or, for the lower ng L-1 concentration. range, water and passage to the microwave digester. The effluent from the digester (at 50°C to 90°C) was merged with a reductant containing 0.2 g L-1 each of NaBH4 and NaOH plus, for urine samples, 400 µL L-1 of Dow Corning 110A antifoaming agent and passed through a hydride manifold and a gas-liquid separator before filtration and cold vapor AAS with or without amalgamation. Peak area or peak height could be measured. Recoveries were improved in some instances by using amalgamation. Sample throughput was 30 to 40 h-1 without and 24 h-1 with amalgamation. The method was successfully applied to rain and to lake and river waters; for 10 mL samples the detection limit with amalgamation was 10 ng L-1. Results on certified reference samples of urine agreed fairly well with certified values. A system for online treatment of liquid samples in a microwave oven and determination of mercury by cold vapor atomic absorption spectrometry was designed and evaluated. The system consisted of an atomic absorption spectrometer, equipped with a mercury-hydride system and amalgamation accessory, a flow injection system, an autosampler and a microwave digestor. Urine and environmental water samples were stabilized with potassium dichromate-nitric acid and were mixed with a bromination reagent. The recoveries of eight mercury compounds from aqueous solutions and five compounds from dilute urine were studied. At an applied microwave power of 75 W, the recoveries of mercury(II) nitrate, methylmercury chloride, amidomercury chloride, phenylmercury chloride and diphenylmercury were between 92 and 102% for 1 + 2 - diluted urine without amalgamation and between 94 and 111% for 1 + 5 diluted urine with amalgamation, respectively. The sample throughput was 30-40 h-1 without amalgamation and 24 h-1 in the amalgamation mode. Good agreement with certificate values was obtained for urine samples. A limit of detection (3s) of 10 ng L-1 was obtained using 10 mL sample volumes of environmental waters (river, lake, rain) and the amalgamation technique. The results compared well with those from an external lab. with correlation coefficients of 0.9302 and 0.9028 (n = 22) for integrated absorbance and peak-height absorbance, respectively.
Mercury Spectrophotometry Sample preparation Microwave Online digestion Amalgamation Reference material

"High-sensitivity Flow Method For The Determination Of Proteins With Micro-flow Plunger Pumps"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 67-74
Takashi Korenaga*, Xiaojing Zhou, Miyoko Izawa, Teruo Takahashi and Tosio Moriwake, Sumio Shinoda

Abstract: Proteins were determined by the dye association method with use of Coomassie Brilliant blue G250 (C. I. Acid Blue 90; I) in conjunction with a flow device based on that of Korenaga and Stewart (Ibid., 1988, 214, 87), which incorporated a double-plunger micro-pump. The device was operated in either flow injection or continuous-monitoring mode (manifolds illustrated). For the former, the sample solution (8 µL) was injected into a stream (0.02 mL min-1) of 0.1 M K2HPO4 - KH2PO4 (pH 7.4) which was then merged with 60 µM-I in 2.8% HClO4, also at 0.02 mL min-1, in a Ti reaction tube (20 cm x 0.5 mm i.d.) before passing through a spectrophotometric flow cell for absorbance measurement at 600 nm. In the continuous mode, the aqueous sample solution and the I reagent (each at 0.02 mL min-1) were mixed in a Ti tube (10 cm x 1 mm i.d.) before entering the flow cell. The best calibration graphs were obtained at low flow rates. Titanium reaction tubes were used because of unstable baseline absorbance obtained with PTFE tubes. For bovine serum albumin determined by the flow injection method, the calibration graph was rectilinear up to 140 µg mL-1, and the standard deviation (n = 10) was 1.5 ng mL-1 at 1.0 µg mL-1. The method was successfully applied to urine samples. To determine microamounts of proteins with low mol. diffusivity, a flow method was developed by both miniaturizing the common flow-injection apparatus and using the dye association method. A very precise double-plunger micropump, which was recently developed for this purpose, was used. The optimum conditions using bovine serum albumin (BSA) as standard and some ion-association dye reagents at very low flow-rates were examined A flow-rate of <50 µL/min was acceptable when a short, small-bore reaction tube was used. Up to 15 samples/h could be analyzed with a relatively long residence time; linear calibration graphs were obtained with both 8 µL volume loop valve injection and no-injection methods. The detection limit and relative standard deviation of the injection method were 0.003 µg/mL and 0.15%, respectively, for BSA.
Albumin Proteins Spectrophotometry Pump Optimization

"Potentiometric Flow Analysis Device Using Membrane-coated Carbon-rod Ion-selective Electrode Detectors"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 399-404
Enju Wang and Satsuo Kamata*

Abstract: To prepare an ion-selective electrode for Cu2+, a carbon rod (7 cm x 4 mm) with a polished tip was coated with a composition containing (by wt.) 3% of tetraisobutylthiuram disulfide, 0.7% of K tetrakis-(4-chlorophenylborate), 63.1% of 2-nitrophenyl octyl ether (I) and 33.2% of PVC; for anions the composition contained 3.3% of propane-1,2-diylbis(diphenylphosphine), 66.7% of I and 30% of PVC. Either electrode was conditioned in 1 mM Cu2+ before use as detector in the PTFE cell of a simple flow system. For the determination of anions, the filtered and diluted sample (30 to 100 µL) was injected into 0.01 M NaH2PO4 as carrier. The peak potential of the electrode was rectilinearly related the log. concentration. of SCN-, ClO4-, NO3- or Cl- over approximately three decades of concentration. For Cu2+, a continuous-flow system was used with the sample stream buffered at pH 6 with 0.01 M acetate. The rectilinear pCu range was 2 to 5.5. Recoveries of Cu2+ or ClO4- were 97% at 50 µM. The flow injection method was successfully applied to the determination of Cl- in seawater and urine. The electrodes could be used continuously for 2 weeks; the carbon rod could then be cleaned and re-coated. A flow-through anal. system that utilizes a membrane-coated carbon rod ion-selective electrode was investigated. Electrodes for Cu2+ based on a thiuram disulfide neutral carrier and for ClO4-, SCN-, NO3- and Cl- based on a bis(diphenylphosphino)propane-copper complex as ion exchanger exhibited satisfactory performance in a continuous-flow system. The response of the anion electrodes in a flow injection system was near Nernstian in the concentration. range 10^-2-10-4 or 10^-5M. Highly reproducible measurements were obtained with sample volumes of 30-100 µL and a sample injection rate of up to 400 h-1. The chloride electrode was suitable for the FIA determination of Cl- in seawater and urine.
Chloride Electrode Electrode Electrode Potentiometry Interferences Apparatus Detector

"Automation Of Enzymic Hydrolysis By Use Of Continuous-flow Methods Involving Immobilized Biocatalysts"
Anal. Chim. Acta 1992 Volume 264, Issue 2 Pages 275-282
J. M. Fern&aacute;ndez-Romero, M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: Two flow injection methods are described and applied to the hydrolysis of 4-nitrophenyl β-D-glucuronide catalyzed by β-D-glucuronidase. The products were monitored: aglycone (spectrophotometric method) and glucuronic acid (chemiluminescent method). Calibration graphs were rectilinear from 1 to 700 µM with a coefficient of variation of 1.5%, and 0.17 to 1.72 mM with a coefficient of variation of 1.4 to 8.1%, for the spectrophotometric and chemiluminescent methods, respectively. The methods may be applied in the determination of illegal drugs in anti-doping control, monitoring pharmaceuticals in therapeutic programmes and monitoring in industrial systems. Two flow injection methods for online enzymatic hydrolysis using immobilized biocatalysts are proposed and applied to the hydrolysis of 4-nitrophenyl-β-D-glucuronide catalyzed by β-D-glucuronidase. Monitoring is performed via the 2 hydrolysis products of glucuronides: the aglucone (specific spectrophotometric method) and glucuronic acid (universal chemiluminescence method). The spectrophotometric method afforded a linear determination range of 1-700 µM with excellent precision, RSD <1.5%, and a sampling frequency of 130 h-1. The chemiluminescence method provided a linear determination range of 0.05-5.5 mM, a RSD between 1.48 and 3.07% for concentrations of 0.17 and 1.72 mM, respectively, and a sample throughput of 25 h-1. The yield of the enzymatic process and the stability of the enzyme reactor were determined by using urine samples. Two fully automated approaches to online hydrolysis and collection and monitoring of the hydrolyzate are also proposed.
4-nitrophenyl β-D-glucuronide Chemiluminescence Spectrophotometry Automation Catalysis Linear dynamic range Process monitoring Immobilized enzyme

"Adsorptive Stripping Voltammetry On Mercury-coated Carbon-fibre Ultra-micro-electrodes"
Anal. Chim. Acta 1993 Volume 273, Issue 1-2 Pages 101-109
J. Amez del Pozo, A. Costa Garc&iacute;a and P. Tu&ntilde;&oacute;n Blanco*

Abstract: The ultra-micro-electrodes were prepared by sealing a 2-cm length of 7.5 µm diameter carbon fiber into a 100 µL micropipette, a 0.5-mm length of the fiber being permitted to project from the micropipette tip; Hg and Cu wire were used for electrical contact. After being cleaned with chromic acid and HNO3 such a micro-electrode was used to determine mitozantrone (I) by immersion in a solution of I in 0.1 M HClO4 containing 0.1 mM Hg(II), which was electro-deposited on the electrode for 60 s at -1.2 V vs. Ag/AgCl. The potential was then held at -0.2 V for, e.g., 3 s before I was determined by phase-selective a.c. voltammetry at 75 Hz with a superimposed voltage amplitude of 25 mV and a detection angle of 90°C. Calibration graphs were rectilinear from 0.5 (detection limit) to 20 nM-I. In the determination of 5 nM-I the RSD was 5.05% (n = 10). In the determination of 10 nM-I there was little or no interference from surfactants, e.g., SDS. Procedures for the determination of I in urine and of folic acid in aqueous solution are also described. Such electrodes, which could be used for 1 to 2 months without loss in sensitivity, might be useful in flow injection analysis or LC.
Mitozantrone Folic acid Voltammetry Electrode Electrode Interferences

"Determination Of Mercury In Urine By Flow Injection Cold Vapor Atomic Absorption Spectrometry"
Anal. Chim. Acta 1993 Volume 278, Issue 1 Pages 189-196
Tiezheng Guo* and J&ouml;rn Baasner

Abstract: Urine (5 ml) was mixed with 0.5 mL of 32% HCl, 0.2 mL of bromate/bromide reagent and 25 µL of Triton X-100 solution for FIA. The solution was injected via a sample loop into the carrier stream (10 ml/min) of 1 M HCl and mixed with 0.25% KMnO4 and 0.2% NaBH4 sequentially. The Ar carrier gas (110 ml/min) was then added to the solution and the mixture entered the gas-liquid separator. The gas phase was swept into an electrically heated quartz cell maintained at 200°C and the Hg vapor was measured. Measurements were carried out at 253.6 nm using either a hollow cathode lamp or a electrodless discharge lamp as the primary light source. The calibration graph was rectilinear for 30 µg/l of Hg with a detection limit of 0.1 µg/l when using a 500 µL sample loop. The RSD (n = 11) was 1.7% for 5 µg/l of Hg(II).
Mercury Spectrophotometry Phase separator Triton X Surfactant

"Room Temperature Phosphorescence Optosensor For Tetracyclines"
Anal. Chim. Acta 1993 Volume 281, Issue 3 Pages 637-644
Fausto Alava-Moreno, Marta Elena D&iacute;az-Garc&iacute;a and Alfredo Sanz-Medel

Abstract: A flow-through optosensor for tetracyclines based on the tetracycline-europium chelate room temperature phosphorescence energy transfer is proposed. The sensor is developed in conjunction with a flow injection analysis system and is based on the transient immobilization on a non-ionic resin (packed in a flow-through cell) of the tetracycline-europium chelate. The analytical performance characteristics of the proposed sensor for semiautomated analysis and control of very low levels of tetracycline were as follows: the detection limits for tetracycline, oxytetracycline and chlortetracycline were 0.25, 0.30 and 0.40 ng mL-1, respectively, with a relative standard deviation of 1% for determination of 0.24 µg mL-1 of each antibiotic (n = 10). Most of the common metal ions in biological samples did not interfere, except Fe(III) which caused serious interference and should be masked with 1,10-phenanthroline. The recommended method has been successfully tested for determination of tetracyclines in clinical samples (urine and pharmaceutical preparations). [References: 18]
Tetracycline Oxytetracycline Chlorotetracycline Phosphorescence Sensor Optosensing Interferences

"Determination Of Traces Of Copper, Cadmium, And Lead In Biological And Environmental Samples By Flow Injection Isotope Dilution Inductively Coupled Plasma Mass Spectrometry"
Anal. Chim. Acta 1993 Volume 284, Issue 1 Pages 181-188
Pei-Ling Lu, Kuang-Shie Huang and Shiuh-Jen Jiang*

Abstract: Flow injection isotope dilution ICP-MS was used in the determination of Cu, Cd, and Pb in SLRS-2 river water and CASS-2 seawater reference materials (National Research Council of Canada) and in freeze-dried urine (NIST SRM 2670) with use of 65Cu, 111Cd and 204Pb as reference isotopes. Isotope ratios for each injection (200 µL) were calculated from the areas of the flow injection peaks and precision was generally 1%. Detection limits were 45, 25 and 58 ng/l for Cu, Cd and Pb, respectively. Both Na and Mg interfered in the determination of Cu and their prior removal was necessary for the analysis of highly saline samples such as seawater. A Tracecon sample pre-treatment system (cf., Ibid., 1993, 282, 437) was used for the separation of Mg and Na and for the pre-concentration of traces of Cu, Cd and Pb in the natural water reference materials. Results obtained for all reference materials agreed well with certificate values.
Copper-65 Cadmium-111 Lead-204 Spectrophotometry Mass spectrometry Reference material Isotope ratio Interferences Preconcentration

"Flow Injection Determination Of Oxalate By A Photoinduced Chemiluminescent Reaction"
Anal. Chim. Acta 1993 Volume 284, Issue 1 Pages 173-179
Tom&aacute;s P&eacute;rez-Ruiz*, Carmen Martinez-Lozano, Antonio Sanz and Otilia Val

Abstract: The method is based on the photochemical decomposition of the Fe(III)-oxalate complex and determination of the resulting Fe(II) from its chemiluminescent reaction with luminol. Urine (235 ml) after the separation of the analyte by calcium precipitation was injected into a 0.5 mM Fe(III)/10 mM H2SO4/0.2% PVA carrier stream (2.7 ml/min) and the mixture passed into a photoreactor comprising a PTFE coil (2.5 m x 0.5 mm i.d.) irradiated with light from a W halogen lamp. The reaction mixture was merged with 0.25 mM luminol/0.5 M borate buffer of pH 11 (5.4 ml/min) reagent solution and the resulting luminescence was measured using a photomultiplier and flow-through cell arrangement. The calibration graph was linear for 0.1-100 µM-oxalate. For 0.5, 5 and 50 µM-oxalate the RSD were 1.9, 1.3 and 0.66%, respectively (10 sets of triplicate injections). In the determination of 0.1-100 µM oxalate the relative errors were ±2.27%. Tolerable amounts are listed for 32 foreign ions. For 0.6-1.4 mM oxalate in urine recoveries were 94.7-98.7%. Results for six urine samples agreed with those obtained by an enzymatic procedure.
Oxalate Chemiluminescence Photochemistry Precipitation

"Catalytic Oxidation And Flow Detection Of Acetaminophen At A Dicyanobis(1,10-phenanthroline)iron(II)-modified Electrode"
Anal. Chim. Acta 1994 Volume 292, Issue 1 Pages 107-112
Huimei Li, Rile Ge and Erkang Wang

Abstract: The electrode was prepared by dipping a vitreous-C electrode (previously polished; details given) in 10 µL of ethanolic 1 mM dicyano-bis(1,10-phenanthroline)iron(II) containing 1% Nafion, and drying under an IR lamp. Before use the electrode was conditioned by cycling the potential for 6 min between -0.2 and +1.1 V (vs. Ag/AgCl reference) at 100 mv/s in 0.1 M KH2PO4 of pH 4. The electrode exhibited an electrocatalytic response in the oxidation of acetaminophen (paracetamol; I) with a reduction of 100 mV in the overvoltage for the electrode process compared to that at a bare vitreous-C electrode. In the flow injection determination of I, sample was injected into a 0.04 M KH2PO4 pH 4.2 carrier stream (1 ml/min) and the peak oxidation current was measured at an applied potential of +0.62 V (vs. Ag/AgCl). The calibration graph was linear from 0.05-100 µg/ml of I with a detection limit of 0.02 µg/ml. For 10 µg/ml the RSD was 5% (n = 20). The electrode was used to determine I in urine by LC. Diluted urine was analyzed on a Nucleosil C18 column (20 cm x 4 mm i.d.) with 0.04 M KH2PO4 buffer solution of pH 4.2 containing 15% methanol as mobile phase (1 ml/min).
Acetaminophen Electrode Electrode LC

"Determination Of Lead By Flow Injection Inductively Coupled Plasma Mass Spectrometry Comparing Several Calibration Techniques"
Anal. Chim. Acta 1994 Volume 293, Issue 1-2 Pages 171-181
Jan Goossens, Luc Moens and Richard Dams*

Abstract: A method for the determination of Pb in wine and urine was developed using a flow injection (FI) system coupled to ICP-MS. The FI system permitted online sample dilution and online internal standardization. Three calibration procedures were compared, viz., online isotope dilution, online standard additions and external calibration. The standard-additions method was preferred with respect to accuracy, precision and flexibility. The FI system was designed so the three streams (A, B and C at 0.6 ml/min each) were merged at two consecutive T-junctions. Streams A and C carried the sample and 50 µg/l of Tl solution (internal standard), respectively. A selector valve was fitted into the third channel so that stream B carried either 0.14 M HNO3 or 100 µg/l of Pb solution in 0.14 M HNO3 (for calibration). A 70 µL portion of the merged streams was injected into the primary carrier stream (0.14 M HNO3 at 1.5 ml/min), transported to the nebulizer and analyzed by ICP-MS. The 200-210 u mass range was scanned entirely. The method was applied to undiluted wines and standard reference urine samples.
Lead Mass spectrometry Mass spectrometry Standard additions calibration Reference material

"Determination Of Reserpine By In Situ Sensitized Photochemical Spectrofluorimetry"
Anal. Chim. Acta 1995 Volume 302, Issue 2-3 Pages 207-214
Jin-Gou Xu*, Hui-Ping Chen, Xiang-Qun Guo and Yi-Bing Zhao

Abstract: An in situ photochemical spectrofluorimetic method for the rapid and precise determination of reserpine was proposed. Adding acetone to the reserpine solution in acetic acid medium will speed up the photochemical conversion of reserpine into an intensively fluorescent compound. The determination can be carried out by measuring the fluorescence intensity at a fixed time. The mechanism of the sensitization of acetone was also discussed. The linear concentration range of the calibration graphs was found to be 0-0.91 µg mL-1. The detection limit was 0.40 ng mL-1 reserpine and the relative standard deviation was 0.75% for 0.40 ng mL-1 reserpine (n = 6). The recovery for its application to reserpine injections was 97.3-103%. Through a standard addition recovery test, we obtained a recovery between 91.3 and 100% in urine samples. Interference effects of some common ions in serum and foreign substances coexisting with reserpine in complex reserpine tablets were also tested.
Reserpine Fluorescence Photochemistry

"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 Fluorescence Heated reaction Interferences Kinetic Stopped-flow

"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 Spectrophotometry Commutation Heated reaction Optimization Zone sampling Kinetic

"Polypyrrole-based Amperometric Flow Injection Biosensor For Urea"
Anal. Chim. Acta 1996 Volume 323, Issue 1-3 Pages 107-113
Samuel B. Adeloju*, Shannon J. Shaw and Gordon G. Wallace

Abstract: An amperometric biosensor for urea was constructed with use of a Pt working electrode coated with a polypyrrole film containing immobilized urease, an Ag/AgCl reference electrode and a Pt auxiliary electrode. The performance of the biosensor was evaluated in an FIA system with 0.05 M phosphate buffer of pH 7 as the carrier stream (0.1 ml/min) and an applied potential of -70 mV vs. Ag/AgCl. A linear response for urea was obtained from the detection limit (3 mg/l) up to 15 mg/l, and the RSD (n = 10) were 2-4% for 9 mg/l of urea. The biosensor responded to both ammonia and ammonium ions, but did not respond to KNO3 or KCl. The biosensor could not be used to determine urea in complex matrices such as urine or blood without sample pretreatment.
Urea Amperometry Electrode Sensor Electrode Sample preparation

"Flow Injection Method For Determination Of Uranium In Urine And Serum By Inductively Coupled Plasma Mass Spectrometry"
Anal. Chim. Acta 1996 Volume 334, Issue 3 Pages 295-301
Avraham Lorber, Zeev Karpas* and Ludwik Halicz

Abstract: Urine acidified with one-hundredth its volume of HNO3 or untreated serum was injected from a 100 µL loop into a carrier stream comprising 0.6% HNO3 containing 1 g/l of Triton X-100. The stream was passed to the ICP nebulizer and the intensity of the 238U+ signal was measured during a dwell time of 250 ms in the mass spectrometer. The total analysis time was 60 s and a throughput of 50 samples per h was achieved. The detection limit was 1.5 ng/l of U. Memory and matrix effects were reduced by adding the Triton to the carrier. The method was applied to the determination of U in samples taken from a population not occupationally exposed to U or its compounds. The technique was validated by analysis of standard reference materials, by dilution experiments and by laser-induced fluorescence.
Uranium Mass spectrometry Reference material Triton X Surfactant

"Fast Automated Determination Of Toxicologically Relevant Arsenic In Urine By Flow Injection Hydride Generation Atomic Absorption Spectrometry"
Anal. Chim. Acta 1997 Volume 349, Issue 1-3 Pages 313-318
T. Guo*, J. Baasner and D. L. Tsalev

Abstract: Lower results for arsenic in urine are encountered when potassium iodide-ascorbic acid is used as a pre-reductant in flow injection-hydride generation atomic absorption spectrometry (FI-HGAAS). For the determination of toxicologically relevant arsenic in urine, i.e. the sum of inorganic As(III) and As(V) and its organic metabolites (monomethylarsonate and dimethylarsinate) has been elaborated a simple analytical procedure: ten-fold diluted urine is treated with L-cysteine (1%, m/v) in 0.03 mol 1-1 hydrochloric acid medium for 1 h, and then a 500 µL aliquot is directly injected into an automated, commercially available FI-HGAAS system. The effects of most critical instrumental and chemical parameters have been studied and optimum conditions are recommended, comprising of relatively low sample and carrier acidities, 0.03 and 0.01 mol L-1 HCl, respectively, higher sodium tetrahydroborate levels (0.5%, m/v), lower flow rates of reagents than that typically recommended for this system to ensure longer reduction and residence times in the gas-liquid separator, and integrated absorbance measurements for eliminating the residual kinetic effects in hydride generation and transport of individual arsenic species. The recoveries of spiked As(III), As(V), MMA and DMA in urine are 100%, 100%, 96% and 95%, respectively. This procedure has been validated by analysis of several certified reference materials and collaborative study samples, the results being in good agreement with the certified values. The limit of detection (3s) is 0.1 µg L-1 in 1:10 diluted urine, corresponding to 1 µg L-1 of As in undiluted urine. The relative standard deviation is 2% and 7% (within-run and between-run in three successive days, respectively) at 3 µg L-1 (1.5 ng) As level. The sampling frequency is up to 50-55 measurements per hour.
Arsenic Spectrophotometry Speciation

"Peroxyoxalate Chemiluminescence In Aqueous Solutions: Coupling Of Immobilized Enzyme Reactors And 1,1'-oxalydiimidazole Chemiluminescence Reaction To Flow Injection Analysis And Liquid Chromatographic Systems"
Anal. Chim. Acta 1997 Volume 357, Issue 1-2 Pages 111-118
Malin Emteborg (b. Stigbrand)a, Knut Irguma,*, Cees Gooijerb and Udo A. Th. Brinkmanb

Abstract: A highly sensitive method for the determination of enzymatically generated hydrogen peroxide in flow-injection analysis (FIA) and liquid chromatography (LC) has been developed. A dual-line flow system is used, one carrier (or eluent) delivering the analyte and the other one the chemiluminescent reagent 1,1'-oxalyldiimidazole (ODI). The results show that the composition of the analyte flow line is not critical for the chemiluminescence detection step; even purely aqueous buffers, as generally applied if immobilized enzyme reactors (IMERs) are involved in FLA and LC, can be used without loss of sensitivity. IMERs containing either glucose oxidase or acetylcholine esterase/choline oxidase were incorporated in this flow line and favourable detection limits (S/N = 3) were obtained, i.e. 3 nM for glucose and 50 nM for acetylcholine and choline. The performance of the approach in real-sample analysis was tested by determining glucose and choline in urine samples.
Glucose Choline Chemiluminescence LC Immobilized enzyme Post-column derivatization Reactor

"Flow Injection Chemiluminometric Determination Of Some Phenothiazines In Dosage Forms And Biological Fluids"
Anal. Chim. Acta 1998 Volume 358, Issue 3 Pages 255-262
Fatma A. Aly, Nawal A. Alarfaj and Abdulrahman A. Alwarthan*

Abstract: A rapid and sensitive flow injection chemiluminometric method is described for the determination of three phenothiazine derivatives, namely, fluphenazine hydrochloride, levomepromazine hydrochloride and trimeprazine tartrate. The method is based on the chemiluminescence (CL) induced by the oxidation of drugs with cerium(IV) in an acidic medium. The CL intensity is greatly enhanced when rhodamine B is used as a sensitizer in the case of levomepromazine hydrochloride and trimeprazine tartrate. The proposed method allows the measurement of 0.5-90 µg mL-1 fluphenazine and 0.1-6.5 µg mL-1 levomepromazine and trimeprazine. The limits of detection (3s) were 0.01 µg mL-1 fluphenazine hydrochloride and 0.1 µg mL-1 for the other two drugs. The method was applied successfully in determining the drugs in dosage form as well as in biological fluids.
Phenothiazines Fluphenazine hydrochloride Levomepromazine hydrochloride Trimeprazine tartrate Chemiluminescence

"Determination Of Corproporphyrin In Urine By Using Stopped-flow Fluoroimmunoassay"
Anal. Chim. Acta 1998 Volume 361, Issue 1-2 Pages 27-32
Evgenia G. Matveevaa, Alexander P. Savitskya and Agustina G&oacute;mez-Hensb,*

Abstract: A simple and fast stopped-flow fluoroimmunoassay method for the direct determination of coproporphyrin in urine is described, which is the first attempt to apply the immunoassay methodology for this analytical purpose. The method is based on the use of the initial rate of the immunochemical reaction as the analytical parameter, which is measured in only 0.5 s through the fluorescence quenching of the porphyrin caused by its reaction with monoclonal antibodies. Stopped-flow mixing technique allows this high initial rate to be easily measured and facilitates the automation of the method. The dynamic range of the calibration graph is 7-100 nM and the relative standard deviation is 1.1-4.0%. Potential interferences from the sample matrix are avoided or minimized by the use of kinetic methodology, so that the pretreatment of the sample is not required. The analytical recoveries obtained by applying the method to urine samples ranged from 88 to 113%
Corproporphyrin Fluorescence Immunoassay Stopped-flow

"Online Preconcentration System For Lanthanum Determination In Urine Using FI-ICP-AES"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 201-207
O. Vicente, A. Masi, L. Martinez*, R. Olsina and E. Marchevsky

Abstract: An online lanthanum pre-concentration and determination system implemented with inductively coupled plasma-at. emission spectrometry (ICP-AES) associated to flow injection (FI) method was studied. For the retention of lanthanum, quinolin-8-ol and Amberlite XAD-7 were used at pH 9.5. The lanthanum complex was removed from the micro-column with nitric acid. The value of detection limit for the pre-concentration of 100 mL of aqueous solution was 0.09 ng mL-1 with a relative standard deviation (RSD) of 1.5%, calculated with the peak heights obtained. The calibration graph using the pre-concentration system for lanthanum was linear with a correlation coefficient of 0.9993 at levels near the detection limits up to at least 100 ng mL-1. The method was successfully applied to the determination of lanthanum in urine samples.
Lanthanum Spectrophotometry Preconcentration Amberlite Complexation 8-Hydroxyquinoline Column

"A Time-based Flow Injection-cold Vapor-atomic Absorption Spectrometry System With Online Microwave Sample Pre-treatment For The Determination Of Inorganic And Total Mercury In Urine"
Anal. Chim. Acta 1998 Volume 369, Issue 1-2 Pages 57-67
M. Gallignani*, H. Bahsas, M. R. Brunetto, M. Burguera, J. L. Burguera and Y. Petit de Pe&ntilde;a

Abstract: A time based injection system used in conjunction with cold vapor generation atomic absorption spectrometry and microwave-aided heating oxidation with potassium persulfate has been developed for the determination of total and inorganic mercury in urine samples. Inorganic mercury is determined after reduction with SnCl2 while total mercury is determined after an online oxidation step with persulfate prior to the reduction step to elemental mercury with SnCl2. The difference between total and inorganic mercury determines the organomercury content in samples. Experimental parameters were optimized by the univariate optimization method. A linear calibration graph was obtained in the range 0.2-20 µg L-1 of Hg2+ by using injection times from 0 to 12 s of a solution of 20 µg L-1 of either inorganic or organic mercury. The detection limit based on 3s of the blank signal was 0.1 µg Hg L-1 regardless of the mercury species under evaluation. The relative standard deviations for five independent measurements were 1.5% and 1.0% for total and inorganic mercury. The recoveries of different amounts of inorganic and organic mercury added to urine samples ranged from 98.5% to 102.2% and from 97.0% to 103%, respectively. Good agreement with certified values of the total mercury containing urine reference materials were also obtained. With the proposed procedure, 20 urine samples of unexposed subjects from Merida city were measured; and the values lay in the range between 1.8 and 6.7 µg l-1. In addition, the use of a mercury standard solution as the carrier converts the flow injection manifold used in this work to an online standard addition system which permits a rapid and simple test for monitoring the mercury levels in these samples.
Mercury(II) Mercury Spectrophotometry Sample preparation Timed injection Speciation Optimization Reference material Microwave Online digestion Standard additions calibration

"Automated Determination Of Lead In Urine By Means Of Computerized Flow Potentiometric Stripping Analysis With A Carbon-fiber Electrode"
Talanta 1987 Volume 34, Issue 6 Pages 539-542
Huang Huiliang, Daniel Jagner and Lars Renman

Abstract: Five different digestion procedures have been investigated. In the recommended procedure 5 mL of concentrated hydrochloric acid-nitric acid mixture (1:1) were added to a 5 mL urine sample. After 1 min the sample was diluted to 100 mL with distilled water. The sample was divided into two 50 mL samples and to one of them a standard addition of 10 µg/l. lead(II) was made. The two samples were analyzed fully automatically by means of computerized flow potentiometric stripping analysis, the main features of the procedure being mercury-film precoating, electrolysis of the sample for 90 sec and subsequent stripping in 1 M calcium chloride/0.1 M hydrochloric acid. Tin and copper were found not to interfere if present at concentrations below 50 mg/l. but high concentrations of tin had to be masked by the addition of copper in order to form a copper-tin intermetallic compound. Complexing agents used in lead poisoning therapy did not interfere with the determination. The lead concentration in a Seronorm® reference urine sample was found to be 93 µg/l. with a standard deviation of 8 µg/l. (n = 5), the certified value being 88 µg/l.
Lead Electrode Potentiometric stripping analysis Automation Computer

"Estimation Of The Method Evaluation Function For The Determination Of Hydride-generating Arsenic Compounds In Urine By Flow Injection Atomic Absorption Spectrometry"
Talanta 1992 Volume 39, Issue 5 Pages 469-474
Ann J. L. M&uuml;rer*, Anne Abildtrup, Otto M. Poulsen and Jytte Molin Christensen,

Abstract: The method described by Hansen et al. (Ann. Occup. Hyg., 1991, 35, 603) was used to validate the analysis in which the samples were injected into a carrier stream and mixed with 0.5% NaBH4 solution in 0.04% NaOH. The generated arsines were carried from a gas - liquid separator by Ar to a quartz cell at 900°C and were determined at 197.3 nm. The evaluation procedure demonstrated that standard-additions calibration was necessary for acceptable performance at low concentration. (i.e., after a low-dose exposure). By this means a limit of detection of 2.9 µg L-1 was achieved. A direct flow injection atomic-absorption spectrometric (FIA-AAS) method for the assessment of inorganic As compounds and their metabolites was developed and statistically evaluated by the estimation of the method evaluation function (MEF), which provides detailed information on the analysis performance of the method. i.e., the average combined uncertainty and the magnitude of potential systematic errors. The method evaluation study demonstrated that the use of standard addition was a necessity to obtain an acceptable method performance at low concentrations. typical for low dose exposure. In contrast, the use of calibration curves resulted in a method with reduced sensitivity and high systematic error. The developed method, using standard addition, had a limit of detection (2.9 µg/mL) sufficiently low for the determination of hydride-generating As species in urine from non-exposed and low exposed persons. Organoarsenicals such as arsenobetaine and arsenocholine are not detected by this method. Hence, the contribution of these compounds derived from a diet containing seafood does not affect the monitoring of inorganic As compounds after occupational or environmental exposure. The high capacity of the FIA-AAS system (31-min per sample measured by standard addition) together with the low limit of detection makes this method suitable for biological monitoring of inorganic As exposure even though standard addition is required.
Arsenic Spectrophotometry Volatile generation Phase separator Standard additions calibration Volatile generation

"Application Of The Slotted Quartz Tube In Flow Injection Flame Atomic Absorption Spectrometry"
Talanta 1992 Volume 39, Issue 6 Pages 581-587
Shukun Xu, Lijing Sun and Zhaolun Fang

Abstract: The feasibility and performance of a combination of a slotted quartz tube and flow injection in flame AAS was studied. A five- to six-fold improvement in tube life was observed relative to continuous aspiration. Flow-impact systems were not needed, so that it was possible to achieve larger enhancement factors without loss of precision. Sensitivity enhancement factors of 3.1, 5.5, 5.3 and 4.0 were obtained for 1.0 mg L-1 of Cu, 1.0 mg L-1 of Pb, 0.1 mg L-1 of Cd and 1.0 mg L-1 of Au with coefficient of variation of 1.3, 1.1, 1.6 and 1.7%, respectively. When the method was applied to the determination of heavy metals in urine, improved tolerance to matrix interference was observed. Recoveries obtained by treating urine samples with 0.1 mg L-1 of Cu and Pb and 0.01 mg L-1 of Cd were 100 to 102%. The slotted quartz tube has been applied to flow injection flame atomic-absorption spectrometry (FI-FAAS) showing several important advantages. The tube life was improved by a factor of 5-6 compared to conventional continuous aspiration. Flow impact systems were found not to be necessary in the applications so that larger enhancement factors may be achieved without sacrifice in precision. For 1.0 mg/L copper, 1.0 mg/L lead, 0.1 mg/L cadmium, and 1.0 mg/L gold sensitivity enhancement factors of 3.1, 5.5, 5.3 and 4.0 were obtained with precisions of 1.3%, 1.1%, 1.6% and 1.7% RSD (n = 11), respectively. Application of the slotted quartz tube FI-FAAS method to the determination of heavy metals in urine has shown improved tolerance to interfering matrixes. Recoveries obtained by spiking undiluted urine samples with 0.1 mg/L copper and lead, and 0.01 mg/L cadmium were in the range 100-102%.
Copper Lead Spectrophotometry Interface Apparatus Interferences Sensitivity

"Individual And Simultaneous Determination Of Uric Acid And Ascorbic Acid By Flow Injection Analysis"
Talanta 1992 Volume 39, Issue 12 Pages 1459-1462
Ala'ddin M. Almuaibed and Alan Townshend

Abstract: The cited procedure uses a combination of spectrophotometry and amperometry based on the measurement of uric acid (I) absorbance at 293 nm and amperometric detection of both analytes at +0.6 V, with the ascorbic acid (II) concentration. being subsequently obtained by difference; the spectrophotometer and mini-amperometric detector were connected in series. The carrier solvent was 0.05 M succinate buffer (pH 3) and the system was optimized for the effects of pH, flow rate and coil length. Calibration graphs for I were rectilinear at 80 and 70 µg mL-1 for detection at 293 nm and +0.6 V, respectively and the coefficient of variation (n = 10) were 1% for both methods at mid-range concentration.; calibration graphs for II were rectilinear at 80 mg L-1 and the coefficient of variation (n = 10) was 0.8% at 30 mg l-1. The limits of detection were 0.12 and 0.15 µg mL-1 for I and II, respectively. The method could be used to determine I and II in biological fluids such as blood and urine, and there was no interference from a variety of species (glucose, ethanol, urea, xanthine, hypoxanthine, cysteine) normally present in biological fluids. Flow injection methods for the individual and simultaneous determination of ascorbic acid and uric acid are proposed. A spectrophotometer and a miniamperometric detector are connected in sequence. The calibration graphs for uric acid obtained by measuring its absorbance at 293 nm and its current at +0.6 V are linear up to at least 80 and 70 µg/mL, respectively, with an relative standard deviation (n = 10) of 1% for both methods at mid-range concentrations. The calibration graph for ascorbic acid with amperometric detection is linear up to 80 mg/L. with an relative standard deviation (n = 10) of 0.8% at 30 mg/L. The simultaneous determination of uric acid and ascorbic acid is based on measurement of the absorbance of uric acid at 393 nm and amperometric determination of both analytes + 0.6 V. The average relative errors of the anal. of binary mixtures of uric acid and ascorbic acid are 2.2 and 4.2%, respectively
Uric acid Ascorbic acid Spectrophotometry Amperometry Simultaneous analysis Dual detection Interferences

"Determination Of Urinary Arsenic And Impact Of Dietary Arsenic Intake"
Talanta 1993 Volume 40, Issue 2 Pages 185-193
Xiao-Chun Le, William R. Cullen* and Kenneth J. Reimer,

Abstract: Urine samples (10 ml) were treated with 0.1 g of L-cysteine to obtain the same sensitivity from As(III), As(V), monomethylarsonic acid and dimethylarsinic acid. Portions (0.1 ml) were injected into the carrier stream and mixed with 0.7 M HCl and 0.65 M NaBH4 in 0.1 M NaOH. The AsH3 generated from these four species were passed through a gas-liquid separator and thence to the air - acetylene flame for AAS. A second sample (40 ml) without the cysteine addition was heated in a microwave oven in the presence of 4.5 g of K2S2O8 and 2.7 g of NaOH for five 3 min periods. This converted all arsenic species to As(V) (including arsenobetaine, which was not reduced to AsH3 by NaBH4). The solution was diluted to 50 mL and the total As(V) was determined as before but with 3 M HCl. This method is capable of differentiating between different sources of urinary intake, e.g., occupational exposure and dietary intake.
Arsenic

"Determinations Of Clodronate In Aqueous Solutions By HPLC Using Post-column Derivatization"
Talanta 1993 Volume 40, Issue 5 Pages 661-667
Vesa Virtanen* and Lauri H. J. Lajunen,

Abstract: Clodronate was separated from aqueous solution by anion exchange on a Dionex HPIC AS7 column eluted with HNO3 - NaNO3 solution and then derivatized with a Th - EDTA - xylenol orange mixed-ligand complex before UV detection at 550 nm. Calibration graphs were rectilinear from 3.1 (detection limit) to 200 ppm; coefficient of variation were 5.5 to 16.6%. The effect of pH on appearance and retention of different forms of clodronate was studied. The method could be used to separate and detect clodronate in urine samples without the usual interference from phosphate.
Clodronate HPLC Spectrophotometry Post-column derivatization Interferences

"Flow Injection Fluorimetric Analysis Of Sulfamethoxazole In Pharmaceutical Preparations And Biological Fluids"
Talanta 1994 Volume 41, Issue 12 Pages 2159-2164
C. Lopez Erroz, P. Vi&ntilde;as and M. Hern&aacute;ndez C&oacute;rdoba*,

Abstract: Pharmaceuticals were dissolved in ethanol and filtered, and urine and serum were diluted with water and filtered. The filtrate was injected into a stream of 0.01 M o-phthaldialdehyde in 0.7 M H3PO4 and merged with a stream of 0.01 M β-mercaptoethanol in 0.7 M H3PO4. The resulting solution flowed through a reactor coil (2.5 m x 0.5 mm i.d.) thermostatted at 40°C and into a flow cell for fluorimetric detection at 412 nm (excitation at 302 nm). The system flow rate was 1 ml/min. The calibration graph was linear for 0.01-2.5 µg/ml of sulfamethoxazole with a detection limit of 7 ng/ml. The RSD (n = 10) were 3.5, 2.2 and 2.1% for 0.01, 0.05 and 1.5 µg/ml, respectively. Interferences from tablet fillers and other compounds are discussed.
Sulfamethoxazole Fluorescence Interferences

"Determination Of Hydrazine Derivatives By Flow Injection Analysis With Spectrophotometric Detection"
Talanta 1995 Volume 42, Issue 10 Pages 1465-1469
M. I. Evgen'ev, S. Y. Garmonova, I. I. Evgen'eva and H. C. Budnikov

Abstract: A diagram is presented of a flow injection manifold used in the spectrophotometric determination of hydrazine-based drugs. The method was based on the reaction of 4-chloro-5,7-dinitrobenzofurazan (DNBF) with the hydrazine derivatives. The 0.02 M DNBF acetonitrile solution was injected directly into a carrier solution of the hydrazine derivatives (concentration range 0.15-4 µg/ml) and the absorbance at 510 nm was measured. For the determination of 1-hydrazinophthalazine hydrochloride in apressin drug, powdered tablets containing ~10 mg of the drug were diluted to 100 mL with water. The mixture was shaken, filtered and a 5 mL portion was diluted to obtain a final solution containing ~1 µg/ml drug. For the determination of hydrazine drugs in plasma, urine and albumin, 1 mL TCA was added to 4 mL sample followed by centrifugation at 6000 rpm. The supernatant was neutralised with 0.5 mL acetate buffer of pH 5.5 and analyzed by the above procedure. The calibration graphs were linear from 0.15-4 µg/ml, with sampling rates of 28-32/h. Interferences from other compounds are tabulated. Flow injection analysis for the determination of hydrazine derivatives based on their nucleophilic substitution reaction with 4-chloro-5,7-dinitrobenzofurazan in aqueous medium, and spectrophotometric detection has been described. The calibration graphs were linear in the range from 0.15 to 4.0 µg mL-1 of hydrazine derivatives, with sampling rates of up to 28-32 samples h-1. Interferences from amino compounds, benzoic acids, aliphatic amines and ammonia have been evaluated. The procedure has been applied to the determination of hydrazine derivatives in serum, urine, apressin drugs and artificial mixtures. (16 references)
Drugs Hydrazine Spectrophotometry Interface Interferences

"Head-space Flow Injection For The Online Determination Of Iodide In Urine Samples With Chemiluminescence Detection"
Talanta 1996 Volume 43, Issue 6 Pages 839-850
J. L. Burguera, M. R. Brunettoa, Y. Contrerasa, M. Burgueraa, M. Gallignania and P. Carreroa

Abstract: Urine and 0.01 M potassium dichromate were agitated for 1.5 min in a headspace vial. The vial was heated for 15 min at 140°C, pressurized with N2 at 45 psi for 0.2 min and the headspace gases passed for 2.5 min into a vial containing 0.1% KI. Streams of trapped iodine and 10 µM-Co(II) were merged (6 and 4.4 ml/min, respectively) and passed to a flow-through cell with a stream of 1 mM luminol (7 ml/min) for 2 s. The emission intensity was measured at 425 nm. Calibration graphs were linear up to 5 mg/l iodine with a detection limit of 10 µg/l. RSD (n = 10) were 1.8% for 50 and 200 µg/l iodine and recoveries were 101-103%.
Iodide Chemiluminescence Sample preparation

"Spectrophotometric Determination Of A Nanomolar Amount Of Ascorbic Acid Using Its Catalytic Effect On Copper(II) Porphyrin Formation"
Talanta 1997 Volume 44, Issue 2 Pages 151-157
Masaaki Tabata*, and Hirofumi Morita

Abstract: A solution (120 µL) containing sample (ascorbic acid), 0.1 M NaNO2, 0.01 M acetate buffer of pH 5, 18 µM-5,10,15,20-tetrakis-(1-methylpyridinium-4-yl)porphyrin and 0.1 mM trans- 1,2-diaminocyclohexane-NNN'N'-tetra-acetic acid (DCTA) was injected into a stream (1.9 ml/min) of water which merged with a stream (1.9 ml/min) of water into which a solution (120 µL) of 0.4 mM Cu(II), 0.1 mM DCTA and 0.1 M NaNO2 in 0.01 M acetate buffer of pH 5 had been injected. The flow passed through a reactor (2 m x 5 mm i.d.) to a detector where the absorbance was measured at 550 nm. The calibration graph was linear for 0.12-0.5 µM-ascorbic acid and the RSD was 2.8% for 0.1 nM-ascorbic acid. No detection limit or recoveries are given. Reducing agents such as sugars and vitamin B compounds did not interfere seriously. The method was applied to urine, tea and blood.
Ascorbic acid Spectrophotometry Indirect Interferences Buffer

"Validation Of The Determination Of Copper And Zinc In Blood Plasma And Urine By ICP-MS With Cross-flow And Direct Injection Nebulization"
Talanta 1997 Volume 44, Issue 8 Pages 1389-1396
J. Szpunar*, J. Bettmer, M. Robert, H. Chassaigne, K. Cammann, R. Lobinski and O. F. X. Donard

Abstract: Use of a Perkin-Elmer cross-flow nebulizer and a direct-injection nebulizer (Microneb 200, CETAC, Omaha, Ne, USA) were compared for the ICP-MS determination of Cu and Zn using an Elan 600 instrument (Perkin Elmer SCIEX). Plasma and urine were diluted 20- and 10-fold, respectively, in 0.05% HNO3 and 10 µg/l 89Y was added as internal standard. Isobaric interferences were eliminated for 65Cu and most of the Zn nuclides. Flow injection direct-injection nebulization was optimized for the analysis of 1-2 µL samples (parameters tabulated). Standard additions was used to eliminate matrix effects. Results using the flow injection method on reference materials agreed with the certified values.
Copper Zinc Mass spectrometry Nebulizer Reference material Interferences Standard additions calibration

"Pulse Injection Analysis With Chemiluminescence Detection: Determination Of Citric Acid Using Tris-(2,2'-bipyridine) Ruthenium(II)"
Talanta 1998 Volume 47, Issue 2 Pages 301-304
He Zhike*, Gao Hua, Yuan Liangjie, Lu Shaofang, Meng Hui, Li Xiaoyan and Zeng Yun'e

Abstract: A chemiluminescence method for the determination of citric acid was developed. The method is based on the enhancement of citric acid on the chemiluminescence light emission of tris-(2,2'-bipyridine)ruthenium(II). In the presence of tris-(2,2'-bipyridine)ruthenium(II), upon the addition of Ce(IV), resulted in intense light emission. The emission intensity is greatly enhanced by the presence of citric acid. The linear range and detection limit of citric acid are 3.0 x 10^-8 ~ 6.0 x 10^-6 mol L-1 and 3.0 x 10^-8 mol L-1, respectively. The precision of the proposed method is determined by analyzing 11 samples containing 1.0 x 10^-7 mol L-1 citric acid. The relative standard deviation is 3.0%. The enhanced mechanism of citric acid was studied. The method was evaluated by carrying out an interference study with common ions and compounds, by a recovery study and by anal. of human urine and orange juice. A satisfactory result was obtained.
Citric acid Chemiluminescence Indirect Interferences

"Indirect Spectrophotometric Determination Of Ascorbic Acid With Ferrozine By Flow Injection Analysis"
Talanta 1998 Volume 47, Issue 3 Pages 531-536
A. Molina-D&iacute;az*, I. Ortega-Carmona and M. I. Pascual-Reguera

Abstract: A FIA indirect spectrophotometric determination of ascorbic acid was developed using its reducing action on Fe(III) in acidic medium and following the spectrophotometric determination of the reduced iron by using sodium 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine-4',4''-disulfonate (ferrozine) as chromogenic reagent in buffered medium (pH 5.5) and monitoring the absorbance signal at 562 nm. A three-line manifold with two reaction coils was used: in the first reaction coil, ascorbic acid reduces Fe(III) to Fe(II); and in the second one, the complexation reaction is developed. The linear range of the method was 0.5-10 µg mL-1 of ascorbic acid, the detection limit being 0.028 µg mL-1. The proposed method was sensitive, rapid (sampling rate of 90 samples h-1) and reproducible (RSD 0.19%, n = 10). Satisfactory results were obtained in the determination of ascorbic acid in pharmaceutical preparations, fruit juices and urine testifying the applicability of the method to real samples.
Ascorbic acid Spectrophotometry Indirect Complexation

"Flow Injection Potentiometric Determination Of Paraquat In Formulations And Biological Samples"
Talanta 1998 Volume 47, Issue 5 Pages 1231-1236
Bahruddin Saad*, Marinah Ariffin and Muhammad Idiris Saleh

Abstract: A flow injection potentiometric method for the rapid determination of paraquat in herbicide formulations and biological samples is described. It is based on the utilization of a flow-through potentiometric detector containing polyvinyl chloride-immobilized octamethylcyclotetrasiloxane, a lipophilic plasticizer (tetra-n-undecyl 3,3',4,4'-benzophenone tetracarboxylate), and membrane additive potassium tetrakis(4-chlorophenyl)borate. The detector was minimally interfered by the presence of constituents such as Na+, K+, Ca2+, Mg2+, glucose, urea, and lactic and citric acids at physiol. levels, respectively. A good correlation between results of the proposed method and HPLC for the formulation samples was found while results for the determination of paraquat in biological samples such as urine, vomitus, and stomach washout was less satisfactory.
Paraquat Potentiometry Electrode Electrode Electrode Interferences Method comparison

"Catalytic-polarographic Determination Of Vanillylmandelic Acid In Urine A Continuous De-oxygenation-flow Injection System"
Analyst 1987 Volume 112, Issue 11 Pages 1593-1596
Teiji Kakizaki, Kiyoshi Hasebe and Hitoshi Yoshida

Abstract: Test solution (25 µL) was injected into a carrier stream (1.6 mL min-1) 0.1 M in formic acid, 1 mM in KBrO3 and 1 µM in sodium molybdate and the resulting product stream was passed through a deoxygenation unit (cf. Trojanek and Holub, Anal. Chim. Acta, 1980, 121, 23) before measurement of the catalytic reduction current due to 4-hydroxy-3-methoxymandelic acid(I), at -0.4 V (vs. Ag - AgCl), at a static-mercury-drop electrode. Measurements could be made in either sampled DC or normal pulse polarographic mode and the respective calibration graphs were rectilinear from 0.1 to 0.6 and 0.1 to 1.4 µg mL-1 of I; the respective coefficient of variation (at 0.4 µg mL-1) and limits of detection were 1.81 and 2.55% (n = 5) and 5.7 and 10 ng mL-1. The effects of 12 potential interferents in urine were generally smaller with normal pulse polarography. The method has been successfully applied to urine samples after cleanup by extraction of I into ethyl acetate (cf. Hasebe et al., Anal. Chem., 1987, 59, 373); the results for 30 samples correlated well (r = 0.9827) with those obtained by HPLC with electrochemical detection.
Vanillylmandelic acid Electrode Polarography Interferences Catalysis Method comparison

"Determination Of Clonazepam By Flow Injection Analysis"
Analyst 1988 Volume 113, Issue 2 Pages 317-319
Cristina Latorre, Manuel Hern&aacute;ndez Blanco, Encarna Lorenzo Abad, Jose Vicente and Lucas Hern&aacute;ndez

Abstract: Clonazepam(I) was determined by flow injection analysis with voltammetric detection at -0.9 V with a vitreous-carbon working electrode, a Ag - AgCl reference electrode containing 3 M KCl and a Au auxiliary electrode, or with spectrophotometric detection at 308 nm. For routine work, a 50-cm reaction coil, a carrier solution of 0.1 M phosphate buffer (pH 7) containing 10% of methanol at a flow rate of 4 mL min-1 and injection volume of 200 µL for voltammetric and 250 µL for spectrophotometric detection were used. For the voltammetric method, response was rectilinear for 6.3 to 31.5 µg mL-1 of I, the detection limit was ~3.3 µg mL-1 and the coefficient of variation was 1%. For the spectrophotometric method, Beer's law was obeyed for 0.6 to 31.5 µg mL-1, the detection limit was 0.2 µg mL-1 and the coefficient of variation was 1.1%. The spectrophotometric method was applied to determine I in urine after extraction with ethyl ether. Beer's law was obeyed for 0.6 to 3.2 µg mL-1 of I and the coefficient of variation (n = 10) at the 2 µg mL-1 level was 2.5%.
Clonazepam Spectrophotometry Electrode Voltammetry

"High Performance Liquid Chromatography Using A Color-forming Agent As A Component Of The Mobile Phase. Separation And Determination Of Magnesium And Calcium In Clinical Samples With O-cresolphthalein Complexan"
Analyst 1988 Volume 113, Issue 2 Pages 247-250
Jun'ichi Toei

Abstract: The cited determination was carried out on a column (5 cm x 4 mm) of TSK-GEL SP-2 SW. The optimum mobile phase (1 mL min-1) contained 0.2 M KCl, 0.02 M acetic acid - Na acetate buffer (pH 4.0) and 0.1 mM o-cresolphthalein complexan. Detection was at 575 nm after mixing the column eluate with 0.4 M NH3 - NH4Cl buffer (pH 10.4). Pre-treatment of samples (milk, urine, serum or saliva) removed protein-bound Ca; pre-treatment on Toyo-Pack SP cartridges to remove free Ca was unsuccessful. Transition metals and Na did not interfere at physiological concentration. The coefficient of variation (n = 7) for 2.1 ppm of Mg and 28.9 ppm of Ca in milk were 1.41 and 1.26%, respectively.
Calcium Magnesium Clinical analysis Spectrophotometry Interferences Post-column derivatization

"Use Of Photochemical Reactions In Flow Injection: Determination Of Oxalate In Urine"
Analyst 1990 Volume 115, Issue 12 Pages 1549-1552
Luis E. Leon, Angel R&iacute;os, M. D. Luque de Castro and Miguel Valc&aacute;rcel

Abstract: The use of photochemical reactions in flow injection (FI) is reported. The irradiation of an FI reactor with a suitable source facilitates the development of the iron(III)-oxalate reaction, allowing the amperometric determination of the anion in the range 1.0-13.0 µg mL-1, with a relative standard deviation of 1.1% and a sampling frequency of 40 h-1. The proposed method was applied successfully to the determination of oxalate in urine samples. Urine (5 ml) was adjusted to pH 5.0 to 5.2 with acetic acid or aqueous NH3 solution, shaken with 0.7 M CaCl2 (2 ml) and kept at 4°C for 2 h, and the ppt. was collected, washed with saturated CaCl2 solution and dissolved in 0.1 M H2SO4. The solution was injected into a carrier stream of 0.1 M H2SO4 and mixed with a reagent stream of 0.1 M H2SO4 containing Fe(III) (both at 0.5 mL min-1) at 40°C in a reactor (1 m x 0.8 mm). The reaction mixture was irradiated before detection at a vitreous C electrode with an auxilliary electrode of the same material vs. Ag - AgCl. The calibration graph was rectilinear from 1 to 13 µg mL-1 of oxalate (I) and the detection limit was 0.64 µg mL-1. Recoveries were 93 to 98% and the coefficient of variation (n = 11) was 2.6 and 1.1% for 1.3 and 9.4 µg mL-1 of I. Citrate and tartrate interfered seriously; malate, picrate, salicylate, and barbituric and uric acids did not.
Oxalate Amperometry Electrode Photochemistry pH Calibration Interferences

"Effect Of Seafood Consumption On The Urinary Level Of Total Hydride-generating Aresenic Compounds. Instability Of Arsenobetaine And Arsenocholine"
Analyst 1992 Volume 117, Issue 3 Pages 677-680
Ann J. L. M&uuml;rer, Anne Abildtrup, Otto M. Poulsen and Jytte M. Christensen

Abstract: A flow injection AAS method for the determination of inorganic arsenic compounds and their metabolites in urine (Muerer et al., Talanta, 1992, 39, 469) was use to investigate the effect of the consumption of seafood on the determination of hydride-generating arsenic compounds (HGAC) in urine. Eating any one of the four fish tested resulted in an increase in these compounds in urine. As the method cannot be used to detect arsenobetaine (I) and arsenocholine (II), the observed increase must originate from HGAC or from degraded I and II. I and II are unstable when incubated in light in the presence of H2O2 and so may be converted to HGAC during storage or cooking. Speciation methods based on HPLC and ICP-AES were also investigated (details given). Arsenobetaine and arsenocholine are considered to be non-toxic and are present as a relatively large proportion of total arsenic in seafoods, and they do not respond to hydride generation. The present study describes the effect of seafood consumption on the urinary concentration of hydride-generating arsenic compounds measured by a newly developed flow injection atomic absorption spectrometric (FI-AAS) method. Consumption of plaice, pighvar and tunny resulted in a 2-fold increase, and consumption of mussels produced a 6-fold increase in the urinary level of hydride-generating arsenic compounds. Hence, a person who has consumed mussels may be suspected of being occupationally or environmentally exposed, if the level of consumption of this seafood is unknown. As the FI-AAS method cannot be used to detect arsenobetaine and arsenocholine, the observed increase in urinary concentration of hydride-generating arsenic compounds after consumption of seafood must originate either from hydride-generating arsenic compounds in the seafood or from degraded arsenobetaine or arsenocholine. The present study has demonstrated that both arsenobetaine and arsenocholine are unstable when incubated in daylight in the presence of hydrogen peroxide, i.e., an oxidizing environment. Hence, it is tempting to speculate that arsenobetaine could be converted into hydride-generating arsenic compounds during storage or cooking of seafood. The feasibility of speciation methods based on high performance liquid chromatographic (HPLC) separation and online analysis by inductively coupled plasma atomic emission spectrometry (ICP-AES) and FI-AAS was also investigated. The FI-AAS system is approximately 35 times more sensitive to the hydride-generating arsenic species than the ICP-AES system.(ABSTRACT TRUNCATED AT 250 WORDS)
Arsenoβine Arsenocholine Spectrophotometry Volatile generation Speciation Volatile generation

"Spectrofluorimetric Flow Injection Method For The Individual And Successive Determination Of L-cysteine And L-cystine In Pharmaceutical And Urine Samples"
Analyst 1992 Volume 117, Issue 6 Pages 1025-1028
Tom&aacute;s P&eacute;rez-Ruiz, Carmen Mart&iacute;nez-Lozano, Virginia Tom&aacute;s and Jos&eacute; Carpena

Abstract: The procedure is based on the rapid oxidation of L-cysteine (I) by Tl(III) with concomitant formation of fluorescent Tl(III). The inclusion of a selecting valve and a Cu-coated Cd column (6 cm x 3 mm) allows the successive determination of I and L-cystine. Calibration graphs were rectilinear from 5 to 50 µM and 2 to 20 µM, resectively. Results are tabulated for the analysis of pharmaceuticals and urine. Recoveries in urine were quantitative. A flow injection configuration is proposed for the determination of L-cysteine and L-cystine individually and for mixtures of both analytes. The procedure is based on the rapid oxidation of L-cysteine by thallium(III) with concomitant formation of fluorescent thallium(I). The inclusion of a selecting valve and of a copper-coated cadmium column in the configuration allows the successive determination of two analytes. Linear calibration graphs were obtained between 5 x 10^-6 and 5 x 10^-5 mol L-1 of L-cysteine and between 2 x 10^-6 and 2 x 10^-5 mol L-1 of L-cystine. The applicability of the method to the determination of L-cysteine and L-cystine in pharmaceutical preparations was demonstrated by investigating the effect of potential interferents and by the analysis of commercial preparations. The method was successfully applied to the determination of L-cysteine and L-cystine in urine samples.
Cysteine Cystine Fluorescence Simultaneous analysis Reduction column Interferences

"Determination Of Ascorbic Acid In Pharmaceuticals And Urine By Reverse Flow Injection"
Analyst 1992 Volume 117, Issue 10 Pages 1635-1638
Ma. Isabel Albero, Ma. Soledad Garc&iacute;a, C. S&aacute;nchez-Pedre&ntilde;o and Jos&eacute; Rodr&iacute;guez

Abstract: Pharmaceutical sample diluted to 250 mL with water and urine sample (15 ml) treated with 2 mL of 0.1 M Na2H2EDTA and diluted to 25 mL with water were analyzed by reverse flow injection based on the reaction with the EDTA - Co(III) complex in a 5% diethylamine medium with spectrophotometric detection at 540 nm. The first flow injection method used peak-height and allowed determination of ascorbic acid (I) from 0.2 to 5 mM; the second, using peak-width, allowed 2 to 50 mM I detection. Recovery of I in urine was quantitative. Effects of foreign ions are tabulated. Two reverse flow injection (FI) methods, using spectrophotometric detection, are proposed for the determination of ascorbic acid. Both methods are based on its reaction with the EDTA-Co(III) complex in a medium of 5% diethylamine. In the first method, using the peak-height FI technique, ascorbic acid is determined over the range from 2 x 10^-4 to 5 x 10^-3 mol L-1 and in the second, using the peak-width FI method, the working range is extended (2 x 10^-3-5 x 10^-2 mol L-1). Both FI methods were applied to the determination of ascorbic acid in pharmaceuticals while the peak-height FI technique was also used to determine ascorbic acid in urine.
Ascorbic acid Spectrophotometry Reverse Peak width Linear dynamic range Interferences

"Flow-through, Microwave-heated Digestion Chamber For Automated Sample Preparation Prior To Inductively Coupled Plasma Spectrochemical Analysis"
Analyst 1994 Volume 119, Issue 5 Pages 1003-1010
Laura J. Martines Stewart and Ramon M. Barnes

Abstract: A microwave-heated flow-through device for online stopped-flow sample digestion is described. The device consists of a digestion chamber (capacity 8 ml) fitted with glass inlet and outlet tubes and a reflux with a condenser attached (diagram given). The device was placed inside a microwave-heating system and used for the digestion of various biological samples. The sample and reagents were transported to the device by a peristaltic pump (concentrated acids were added manually). Digestion was effected with HNO3, HNO3/H2SO4 and H2O2 in several stages using various microwave heating powers and reaction times (details tabulated). After digestion, the solution was analyzed by ICP-AES. The method was used to determine several metals in milk, blood and urine. Quantitative results were obtained. The method afforded results comparable to those obtained by a high-pressure ashing method.
Metals Sample preparation Spectrophotometry Microwave Online digestion Stopped-flow

"Determination Of Trace Amounts Of Urea By Using Flow Injection With Chemiluminescence Detection"
Analyst 1994 Volume 119, Issue 8 Pages 1829-1833
Xincheng Hu, Norimichi Takenaka, Masaru Kitano, Hiroshi Bandow, Yasuaki Maeda and Masaharu Hattori

Abstract: Sample was injected into a carrier stream (10 ml/min) of water and passed through a cation-exchange column before merging with a reagent stream (10 ml/min) consisting of 0.04 M sodium hypobromite and 0.2 M NaOH. The two solutions were fed into a double concentric tube mixer before passing to the reaction cell. The chemiluminescence emitted was measured at 510 nm. Diagrams of the flow injection manifold and the chemiluminescence cell and mixer used are given. The calibration graph was linear from 0.5-50 µM-urea with a detection limit of 90 nM. The RSD (n = 6) for 0.5 µM-urea was 1.9%%. The method was used to determine urea in urine and natural water. The results obtained agreed with those obtained by a spectrophotometric method.
Urea Chemiluminescence Spectrophotometry

"Flow Injection Potentiometric And Voltammetric-stripping Analysis Using A Dialysis Membrane Covered Mercury Film Electrode"
Analyst 1994 Volume 119, Issue 8 Pages 1813-1818
Joseph H. Aldstadt, Dewey F. King and Howard D. Dewald

Abstract: The cited electrode was prepared by fixing a cellulose triacetate dialysis membrane to the end of a vitreous C electrode. The Hg film was deposited on the electrode from an acidified mercury(II) nitrate solution (details given). The electrode was incorporated in a wall-jet flow cell (diagram given) and used for the determination of Pb in various samples. Water and urine were acidified with 0.5 M HNO3. Blood (10 µL) was diluted (1:29) with 5% HCl or Metexchange M reagent. A 190 µL portion of the resulting solution was injected into a carrier stream (1.1 ml/min) of 10 mM KNO3/10 mM HNO3 and transported to the wall-jet cell. Pb was determined by Osteryoung square-wave anodic-stripping voltammetry (OSWASV) or by potentiometric-stripping analysis (PSA; details given). The flow was stopped during the deposition and stripping cycles. OSWASV was applied to water: the calibration graph was linear up to 1000 ppb of Pb; RSD (n = 8) were 1.7-6%. PSA was applied to all the samples: for water and urine, RSD (n = 8) were 3-5.4%. For blood, the calibration graph was linear up to 60 ppb of Pb; the detection limit was 2.7 ppb; RSD (n = 8) were 5.3-10.6%.
Lead Voltammetry Potentiometric stripping analysis Electrode Electrode Dialysis

"Screening Of Cattle Urine Samples For The Presence Of β-agonists With A Functional Test: Some Preliminary Results"
Analyst 1994 Volume 119, Issue 12 Pages 2667-2670
Robert Schilt, Hendricus Hooijerink, Fred A. Huf, Obbe P. Zuiderveld and Aalt Bast

Abstract: A new procedure based on the measurement of biological effects has been developed for the determination of residues of β-agonists, such as clenbuterol, in urine. A multi-chamber superfusion apparatus containing isolated trachea strips from guinea pigs was used to detect smooth muscle relaxation induced via beta 2-adrenoceptor activation. The trachea tissue was pre-contracted with metacholine. Urine samples were extracted using a solid-phase column containing reversed-phase and anion-exchange materials. Extracts were introduced into the superfusion apparatus via flow injection. The intensity and response of relaxation are dependent on the type and concentration of the β-agonist introduced. The sensitivity of the assay for clenbuterol in calf urine is about 1 µg L-1. This methodology in the present form is especially suitable for survey screening analysis for several types of samples. An extensive validation of the procedure is performed to determine the range of analytes that can be detected, the possibilities of analyzing urine samples obtained from mature cattle or other animal species and the influence of cross-reacting substances.
Clenbuterol Sample preparation Superfusion

"Flow Injection Spectrofluorimetric Determination Of Oxalate Based On Its Enhancing Effect On The Oxidation Of Rhodamine B By Dichromate"
Analyst 1995 Volume 120, Issue 8 Pages 2111-2114
Tom&aacute;s P&eacute;rez-Ruiz, Carmen Mart&iacute;nez-Lozano, Virginia Tom&aacute;s and Rocio Casaj&uacute;s

Abstract: The sample was mixed with a 10 µM-Rhodamine B solution and a portion (100 µL) of the mixed solution was injected into a pre-mixed stream (1.2 ml/min) of 0.4 M H2SO4 and 2 mM potassium dichromate. The sample zone was then passed through a 60 cm reaction coil. A stop time of 60 s was applied while the sample zone was in the reaction coil, after which the flow was re-started and the decrease in the fluorescence intensity of the sample zone was measured at 577 nm (excitation at 561 nm). A diagram of the manifold used is given. The calibration graph was linear from 1.76-88 µg/ml of oxalate (I). RSD (n = 10) were 0.84 and 0.26%, respectively for 17 and 68 µg/ml of I. The throughput was ~e;35 samples/h. The method was applied to the analysis of I in urine and spinach after appropriate sample pre-treatment (details given). Recoveries of oxalate from both urine and spinach were >93%.
Oxalate Fluorescence Stopped-flow

"Room Temperature Phosphorescence Optosensor For Anthracyclines"
Analyst 1998 Volume 123, Issue 1 Pages 151-154
Fausto Alava-Moreno, Mar&iacute;a Jes&uacute;s Valencia-Gonz&aacute;lez and Marta Elena D&iacute;az-Garc&iacute;a

Abstract: A flow-through optosensor for anthracyclines based on the anthracycline-europium chelate room temperature phosphorescence energy transfer is proposed. The sensor was developed in conjunction with a flow injection analysis system and is based on the transient immobilization on a non-ionic resin (packed in a flow-through cell) of the anthracycline-europium chelate. The analysis performance characteristics of the proposed sensor for semi-automated analysis and control of very low levels of anthracycline were as follows: the detection limits for daunorubicin, doxorubicin and epirubicin were 9.0, 5.8 and 5.8 ng/mL, respectively, with an RSD of 1% for the determination of 0.22 mg/mL of each anthracycline (n = 10). Most of the common metal ions in biological samples did not interfere, except Fe(III), which caused serious interference and should be masked with 1,10-phenanthroline. The recommended method was successfully tested for determination of anthracyclines in clinical samples (urine and pharmaceutical preparations).
Anthracyclines Sensor Phosphorescence Interferences Solid phase detection

"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 Electrode Electrode Immobilized enzyme Reagent recycling Heated reaction

"Indirect Atomic Absorption Spectrometric Determination Of Sulfonamides In Pharmaceutical Preparations And Urine By Continuous Precipitation"
J. Anal. At. Spectrom. 1988 Volume 3, Issue 5 Pages 725-729
Rosa Montero, Mercedes Gallego and Miguel Valc&aacute;rcel

Abstract: Two AAS methods are described that are based on continuous precipitation of sulfonamides with Ag+ or Cu(II) in a flow injection system (illustrated). Sample solution (100 µL) containing 10 to 100 µM-sulfonamide at pH 7.6 to 9.0 was continuously pumped into the system and mixed with carrier solution (200 µg mL-1 of Ag; 1.5 mL min-1, or 150 µg mL-1 of Cu; 3.1 mL min-1) at pH 6 to 7 in a 200-cm reaction coil. The peak due to the precipitating cation in a water blank was recorded first and then the peak due to the ppt. retained on a stainless-steel filter (pore size 0.5 to 2.0 µm) was measured. Sulfonamide concentration. was obtained from the difference between the two peaks. Response was rectilinear for 2.5 to 35 µg mL-1 of sulfonamide by either method, and detection limits were 1.2 and 1.4 µg mL-1 for the Ag and Cu methods, respectively. Recoveries from pharmaceuticals were quantitative. The coefficient of variation (n = 11) ranged from 1.5 to 3.0%. The Cu method was more selective than the Ag method, and could be used to determine sulfonamides in urine.
Sulfonamides Spectrophotometry Precipitation Indirect

"Determination Of Arsenic In Environmental And Biological Samples By Flow Injection Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 1 Pages 31-35
Meng-Fen Huang, Shiuh-Jen Jiang and Chorng-Jev Hwang

Abstract: A simple and very inexpensive in situ nebulizer-hydride generator was used with inductively coupled plasma mass spectrometry (ICP-MS) for the determination of arsenic in environmental and biological samples. The application of hydride generation (HG)-ICP-MS alleviated the spectral interferences and sensitivity problems of arsenic determinations encountered when conventional pneumatic nebulization is used for sample introduction. The sample was introduced by flow injection to minimize deposition of solids on the sampling orifice. The arsenic in the sample was reduced to As(III) with L-cysteine before being injected into the HG system. A detection limit of 0.003 ng ml-1 was obtained for arsenic. The method has been successfully applied to the determination of arsenic in National Research Council of Canada reference materials, CASS-2 (Nearshore Seawater Reference Material for Trace Metals), NASS-3 (Open Ocean Reference Material for Trace Metals) and SLRS-2 (Riverine Water Reference Material for Trace Metals), and in National Institute of Standards and Technology, Standard Reference Material 2670, Toxic Metals in Freeze-Dried Urine. Precision was less than 5% and analysis results were within 6% of the certified values for all determinations.
Arsenic Mass spectrometry Volatile generation Volatile generation

"Automated Online Separation-preconcentration System For Inductively Coupled Plasma Atomic Emission Spectrometry And Its Application To Mercury Determination"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 4 Pages 243-248
Pedro Ca&ntilde;ada Rudner, Amparo Garcia de Torres, Jose M. Cano Pav&oacute;n and Enrique Rodriguez Castellon

Abstract: An automated separation-pre-concentration system coupled to an inductively coupled plasma atomic emission spectrometer is described. The pre-concentration step is performed on a chelating resin microcolumn [silica gel functionalized with 1,5-bis(di-2-pyridyl) methylene thiocarbohydrazide] placed in the injection valve of a simple flow manifold. The system was applied to the determination of mercury in sea-water and biological samples. The optimum experimental conditions were evaluated for the continuous pre-concentration of mercury, the direct generation of mercury vapor and the final determination of this element by ICP-AES. The proposed method has a linear calibration range from 2 to at least 1000 ng mL-1 of mercury, with a detection limit of 1 ng mL-1 (S/N = 3) and a throughput of 40 samples h-1, for a 6 mL sample volume The accuracy of the method was examined by the anal. of certified reference materials and by determining the analyte content in spiked environmental waters. The results show sufficiently high recoveries.
Mercury Spectrophotometry Reference material Preconcentration Optimization Resin Chelation Silica gel

"Selective Voltammetric Detection Based On Adsorptive Preconcentration For Flow Injection Analysis"
Anal. Chem. 1983 Volume 55, Issue 8 Pages 1285-1288
Joseph Wang and Bassam A. Freiha

Abstract: The cited detection technique, which is more selective than conventional amperometric detection, is exemplified by the determination of chlorpromazine(I) in the presence of a 10-fold excess of a species of similar redox potential, e.g., Fe(CN)64- or ascorbic acid, that is not adsorbed on the working electrode. A 0.1 M phosphate buffer carrier solution is passed through the cell, the sample is injected from a loop, and, after a delay of 5 s, adsorptive pre-concentration of I at +0.3 V for 1 min is initiated at a carbon-paste working electrode, the silver - AgCl reference and platinum auxiliary electrodes being mounted downstream. The adsorbed I is subsequently determined by application of a differential pulse anodic potential ramp to +0.9 V. The next injection follows cleaning of the working electrode by maintaining it at +0.9 V for 1 min. The effects of pre-concentration period, flow rate, scan rate and concentration. of I have been investigated. I was determined directly in urine after dilution of the sample with a threefold volume of carrier solution At a flow rate of 0.3 mL min-1, 24 samples can be analyzed in 1 h, and the detection limit is a few ng.
Chlorpromazine Clinical analysis Electrode Spectrophotometry Voltammetry Preconcentration

"Determination Of Orthophosphate By Flow Injection Analysis With Amperometric Detection"
Anal. Chem. 1984 Volume 56, Issue 12 Pages 2218-2223
Sara M. Harden and William K. Nonidez

Abstract: The simple system described is capable of analyzing 70 samples h-1 at a flow rate of 2.2 mL min-1. It involves measurement, in an aqueous solvent system of 0.1 M HNO3, 1.95 mM Na2MoO4 and 30% (v/v) methanol, of the reduction current of previously formed 12-molybdophosphoric acid at a platinum electrode in a commercial amperometric thin-layer detector (Bioanalytical Systems). The peak area is rectilinearly related to PO43- concentration. up to 50 µM, the detection limit (signal-to-noise ratio = 2) is 0.02 µM in the original sample, and the coefficient of variation (n = 5) at the 1 µM level is 2.6%. For the determination of P in 10 samples of urine, results by the proposed method did not differ at the 95% level of confidence from those obtained by a spectrophotometric method. Silicate in a ratio of 10:1 to PO43- interferes substantially, as do Fe(III) at 1:10, Cu(II) at 1:1 and As at 10:1; glucose does not interfere even in a ratio of 100:1.
Phosphate Amperometry Electrode Interferences Method comparison

"Determination Of Conjugated Glucuronic Acid By Combining Enzymic Hydrolysis With Lucigenin Chemiluminescence"
Anal. Chem. 1985 Volume 57, Issue 1 Pages 46-51
Lori L. Klopf and Timothy A. Nieman

Abstract: The samples pass in a continuous-flow system through a column packed with controlled-porosity glass on which β-glucuronidase is immobilized, and the resulting glucuronic acid is mixed with streams containing NaOH, lucigenin and Na dodecyl sulfate, the chemiluminescent emission intensity being proportional to the free glucuronic acid and therefore to the original glucuronide concentration. Detection limits for phenyl, nitrophenyl, methylumbelliferyl, bromonaphthyl, oestradiol and androsterone glucuronides are from 5 to 10 µM, calibration graphs being rectilinear to 2 mM. The placement of a HPLC Partisil SAX column after the enzyme reactor removes interfering compounds. Results are given for the determination of total glucuronides in urine, and the application of the method to blood is envisaged.
Glucuronic acid Glucuronides, phenyl Glucuronides, nitrophenyl Glucuronides, methylumbelliferyl Glucuronides, bromonaphthyl Glucuronides, oestradiol Glucuronides, androsterone Chemiluminescence Interferences Controlled pore glass Immobilized enzyme

"Thin Layer Electrochemical Detector With A Glassy Carbon Electrode Coated With A Base Hydrolyzed Cellulosic Film"
Anal. Chem. 1985 Volume 57, Issue 8 Pages 1536-1541
Joseph Wang and Lori D. Hutchins

Abstract: Vitreous-carbon electrodes were coated with cellulose acetate, which was then hydrolyzed in alkali to increase its porosity; by hydrolysing the film for different time periods, different permeabilities (i.e., MW cut-off) were achieved, thus greatly improving the selectivity of the coated electrode. High selectivity to smaller analytes (MW <200) was demonstrated in liquid chromatographic and flow injection systems, and electrode poisoning due to protein adsorption was minimized. Applications to the determination of, e.g., paracetamol, in diluted urine are described.
Acetaminophen Electrode Electrode

"Two-valve Injector To Minimize Nebulizer Memory For Flow Injection Atomic Absorption Spectrometry"
Anal. Chem. 1985 Volume 57, Issue 9 Pages 2015-2016
James M. Harnly and Gary R. Beecher

Abstract: A single-line flow injection system for flame AAS with use of a pneumatic nebulizer has been modified to include three pumps and a second six-port rotary value (to reduce memory effects). The system was applied to the determination of K, Mg, Na and Zn in urine at a flow rate of 1.6 mL min-1. The blank signal returned to its starting value after two atomizations, and a 10-fold reduction of the nebulizer memory over the previous system was achieved.
Potassium Magnesium Sodium Zinc Spectrophotometry Apparatus Nebulizer Valve

"Determination Of Creatinine By An Ammonia-sensitive Semiconductor Structure And Immobilized Enzymes"
Anal. Chem. 1986 Volume 58, Issue 1 Pages 145-148
Fredrik Winquist, Ingemar Lundstroem, and Bengt Danielsson

Abstract: The determination is described of creatinine in biological samples, by using an enzymatic flow injection system (diagram presented). A 25-fold dilution was used for whole blood and plasma and a 1000-fold dilution for urine. An NH3-sensitive Ir - metal oxide semiconductor sensor was developed to detect the NH3 produced by immobilized creatinine deiminase. Endogenous NH3 was removed by the action of immobilized glutamate dehydrogenase. The sensitivity for 85 µL aliquots was 0.2 µM-creatinine and the calibration graph was rectilinear for up to 30 µM. The results correlated well with those obtained by conventional spectrophotometry. The recoveries ranged from 93 to 105% and the only significant interferences were from low-mol.-wt. amines.
Creatinine Electrode Interferences Immobilized enzyme Method comparison

"Liquid Chromatographic Determination Of Penicillins By Post-column Degradation With Sodium Hypochlorite"
Anal. Chem. 1986 Volume 58, Issue 8 Pages 1896-1898
Jun Haginaka and Junko Wakai

Abstract: Separation of benzylpenicillin potassium(I), ampicillin(II), ciclacillin(III), carbenicillin sodium(IV) and ticarcillin sodium (V) was effected by HPLC on a column (15 cm x 4.6 mm) of Develosil ODS-5 with post-column derivatization with 0.02% NaClO in 0.5 M NaOH and detection at 280 to 284 nm. The mobile phase for I, II and III was 2 mM NaH2PO4 - 2 mM Na2HPO4 - methanol (1:1:1); that for (IV) and V was 15 mM tetrabutylammonium bromide - 3 mM NaH2PO4 - 3 mM Na2HPO4 - methanol (2:2:2:5). Calibration graphs were rectilinear for 0.2 to 100 µg mL-1 of each penicillin; detection limits were 100 ng mL-1 of I, II and III and 200 ng mL-1 of (IV) and V. The coefficient of variation at 5 µg mL-1 were <4.5%. Separation of II from its urinary metabolites was similarly carried out on a Nucleosil 5C18 column (15 cm x 4.6 mm) with 15 mM Na heptanesulfonate - 3 mM NaH2PO4 - 27 mM H3PO4 - methanol (3:3:3:5) as mobile phase; the detection limit was 0.5 µg mL-1.
Penicillins HPLC Spectrophotometry Post-column derivatization

"Poly(4-vinylpyridine) Coated Glassy Carbon Flow Detectors"
Anal. Chem. 1987 Volume 59, Issue 5 Pages 740-744
Joseph Wang, Teresa Golden, and Tuzhi Peng

Abstract: A vitreous-carbon thin-layer electrochemical detector (Model TL-5, Bioanalytical Systems) was incorporated in a flow injection system (cf. Wang and Hutchins, Ibid., 1985, 57, 1536) with a silver - AgCl reference electrode and a stainless-steel auxiliary electrode located in a downstream compartment. The vitreous-carbon electrode was polished with α-alumina particles (0.05 µm), washed and modified by dipping for 30 s in methanolic 0.4% poly-(4-vinylpyridine) to give an 11 µm-thick coating. A further coating to provide protection from organic surfactants was obtained by dipping in a 5% cellulose acetate solution in acetone - hexane (1:1) followed by hydrolysis for 40 min in 0.07 M KOH. The performance of the electrode, which excludes cationic species, was evaluated for its performance with respect to film thickness and reproducibility, system flow rates and solute concentration. The detector could also be used in HPLC systems.
Ascorbic acid Amperometry Electrode Interferences

"Stable Modified Electrodes For Flow Injection Amperometry. Application To The Determination Of Thiocyanate"
Anal. Chem. 1988 Volume 60, Issue 17 Pages 1710-1713
James A. Cox, Thomas Gray, and Krishnaji R. Kulkarni

Abstract: Platinum electrodes were modified by adsorption of iodine and coating with cellulose acetate, and vitreous-carbon electrodes were anodized with RuCl3 - K4Ru(CN)6. The modified electrodes were incorporated into flow injection systems for determination of SCN-. The carrier streams used for the Pt and the vitreous-carbon electrode systems were 0.2 M NaCl (adjusted to pH 4 with HCl) and 0.2 M K2SO4 (adjusted to pH 2 with H2SO4), respectively. All amperometric measurements were made vs. Ag - AgCl. Rectilinear calibration graphs were obtained for 5 µM to 0.1 mM SCN- and for 0.2 to 4.0 µM-SCN- with the Pt and vitreous-carbon electrodes, respectively. However, the latter electrode was stable for longer than the Pt electrode. The method was applied in the determination of SCN- in urine; interference from uric and ascorbic acids was removed by controlled-potential electrolysis before analysis.
Thiocyanate ion Amperometry Electrode Electrode Electrode Interferences

"Determination Of Low Parts Per Billion Levels Of Amines In Urine By Liquid Membrane Sample Clean Up Directly Coupled To A Gas-liquid Chromatograph"
Anal. Chem. 1988 Volume 60, Issue 13 Pages 1340-1347
Gudjon Audunsson

Abstract: An automated sample preparation method is described in which urine at alkaline pH is extracted wih undecane immobilized on a PTFE membrane (Fluoropore FG). Basic components are trapped in an acidic acceptor phase on the other side of the membrane. The accumulated amines are transferred to an interface which injects a 10 µL portion on to a glass column (2 m x 3 mm) of Gas-Chrom R (80 to 100 mesh) coated with Pennwalt 223 containing 4% of KOH. The carrier gas (25 mL min-1) is N, and N-selective detection is used. The detection limit (e.g., ≈1 ppb for triethylamine) is about two orders of magnitude lower than that of a manual GC method for pure aqueous solution The overall precision is 3.5 to 4% for amine concentration. of 1 ppb.
Amines Clinical analysis GC Sample preparation Extraction Preconcentration

"Separation Of Trace Metal Complexes For Analysis Of Samples Of High Salt Content By Inductively Coupled Plasma Mass Spectrometry"
Anal. Chem. 1989 Volume 61, Issue 2 Pages 149-153
Michael R. Plantz, James S. Fritz, Fred G. Smith, and R. S. Houk

Abstract: Solutions of trace metals (Au, Bi, Co, Cr, Cu, Fe, Hg, Mo, Nb, Ni, Pt, Tl, U and V) in aqueous media of high salt content were treated with bis(carboxymethyl)dithiocarbamate reagent (prep. described) and injected into the loading solvent (0.05 M formate buffer of pH 3.25) for application to a column of Amberlite XAD-4 resin. The adsorbed complexes were eluted with aqueous 0.1 M NH3 (pH 11) and the eluate was analyzed by ICP-MS on a Sciex Elan model 250 instrument fitted with a continuous-flow ultrasonic nebulizer. Detection limits in salt-rich aqueous solution ranged from 6 ng L-1 for Bi to 80 ng L-1 for Pt. The method has been used to determine Cr, Ni and Pt in urine, and trace metals in seawater.
Chromium Nickel Platinum Mass spectrometry Column Instrumentation Nebulizer Amberlite Preconcentration Complexation Buffer

"Copper Determination In Urine By Flow Injection Analysis With Electrochemical Detection At Platinum Disk Microelectrodes Of Various Radii"
Anal. Chem. 1990 Volume 62, Issue 1 Pages 27-31
Darryl L. Luscombe, Alan M. Bond, David E. Davey, and John W. Bixler

Abstract: The incorporation of platinum disk microelectrodes of various radii (2.5-50 microns) in a well-jet flow cell offers reduced limits of detection for the determination of copper in urine by flow injection analysis compared with standard methods based on a conventional sized glassy carbon disk macroelectrode (radius 1.5 mm), in a thin-layer cell. The radius of the platinum disk microelectrode was found to be critical with respect to both the limit of detection and flow rate dependence. An optimal radius value of 28 microns was found with detection limits increasing with both larger and smaller electrode radii. In contrast, as theoretically expected, a diminished flow rate dependence was observed the smaller the radii of the platinum disk microelectrodes. Sample cleanup and preparation is conveniently achieved by the use of Sep-Pak cartridges and formation of a copper dithiocarbamate complex. The metal complex is easily oxidized at platinum disk microelectrodes in acetonitrile, which was the solvent used in the flow injection method of analysis.
Copper Electrode Electrochemical analysis Flowcell Detection limit Glass Complexation Standard method Method comparison

"Multi-channel Electrochemical Detection With A Micro-electrode Array In Flowing Streams"
Anal. Chem. 1992 Volume 64, Issue 1 Pages 44-49
Atsushi Aoki, Tomokazu Matsue, and Isamu Uchida

Abstract: A 16-channel microelectrode array was used to develop a multi-channel electrochemical detection system for flow injection analysis (FIA) and HPLC. Current responses at 16 micro-band electrodes held at different potentials (controlled by a multi-potentiostat) were collected to provide three-dimensional results of time, current and potential. The calibration graph was rectilinear from 10 nM (detection limit) to 1 mM of (ferrocenylmethyl)trimethylammonium. A 5-step potential staircase of 10 mV step height was applied to the 16 electrodes to give 80-channel detection, and this system was applied to FIA and HPLC of a mixture of ferrocene derivatives, ascorbic acid, uric acid and catecholamines. Eighty data points could be obtained in 0.26 s. The detection of uric acid and ascorbic acid in blood and urine was demonstrated.
Ascorbic acid Uric acid Catecholamines Electrode Apparatus Detector

"Determination Of Total Mercury In Waters And Urine By Flow Injection Atomic Absorption Spectrometry Procedures Involving On- And Off-line Oxidation Of Organomercury Species"
Anal. Chem. 1993 Volume 65, Issue 5 Pages 653-656
Christopher P. Hanna, Julian F. Tyson, and Susan McIntosh

Abstract: Potable, river, pond or simulated waste water with added methylmercury chloride (20 ng mL-1 of Hg) was analyzed directly. Urine with Hg (100 ng mL-1) added as inorganic Hg, methylmercury chloride or phenylmercury acetate was either diluted with water and analyzed directly or treated with solid KMnO4 and H2SO4, clarified with 25% hydroxylammonium chloride and diluted with water for analysis. The sample was injected into water as carrier, and this stream was merged with concentrated H2SO4 in a 30-cm reaction coil. The resulting stream was merged with 5% K2S2O8 solution in a 150-cm coil, and 10% SnCl2 solution in 10% HCl was incorporated with passage through a 30-cm coil. Argon was introduced into the mixed solution, which passed through a further 30-cm coil and then through two gas - liquid separators, from the second of which the vapor passed to the AAS system for measurement at 253.7 nm. An amalgam system was used in parts of the study to trap the Hg on a Au - Pt gauze before thermal desorption and detection. No interference was caused by up to 2% of Cl- or up to 1 mg L-1 of S2- in the sample, and there was no problem from residual water vapor. The detection limit was 0.14 ng mL-1 of Hg, and the coefficient of variation (n = 3) was 1.4% at 10 ng mL-1 of Hg. Online oxidation afforded quantitative recovery of all forms of Hg added to water samples, but recovery of phenylmercury acetate from urine was 45% and that of methylmercury chloride was negligible, although inorganic Hg was fully recovered; off-line oxidation gave quantitative recovery of all species.
Mercury Methylmercury ion Phenylmercury Mercury(II) Spectrophotometry Speciation Amalgamation Interferences Volatile generation PPB Volatile generation

"Measurement Of Vanadium, Nickel, And Arsenic In Seawater And Urine Reference Materials By Inductively Coupled Plasma Mass Spectrometry With Cryogenic Desolvation"
Anal. Chem. 1993 Volume 65, Issue 18 Pages 2468-2471
Luis C. Alves, Lloyd A. Allen, and R. S. Houk

Abstract: Addition of a small dose (2%) of H2 to the aerosol gas flow enhanced analyte signals by a factor of 2-3, which compensated for the loss of analyte signal that accompanied earlier efforts at cryogenic desolvation with inductively coupled plasma mass spectrometry (ICP-MS). Vanadium, nickel, and arsenic at microgram per liter levels in urine, river, and seawater reference materials were determined. The polyatomic ions ClO+, CaO+, and ArCl+, which normally cause severe overlap interferences for these elements, were attenuated to manageable levels by cryogenic desolvation. The samples were simply diluted with 1% HNO3 so that the chloride could be removed as HCl. The analytical results obtained for these standard reference materials agreed closely with the certified or recommended values. The detection limit ranges (3s) obtained were 10^-1000 ng L-1 for V, 0.03-20 µg L-1 for Ni, and 4-7000 ng L-1 for As in the original samples. The samples were introduced by flow injection to minimize clogging of the sampling orifice.
Vanadium Nickel Arsenic Mass spectrometry Reference material Interface Interferences

"Online Monitoring Of Hydrophobic Compounds At Self-assembled Monolayer Modified Amperometric Flow Detectors"
Anal. Chem. 1993 Volume 65, Issue 14 Pages 1893-1896
Joseph Wang, Hui Wu, and Lucio Angnes

Abstract: Substantial improvements in the selectivity of amperometric monitoring of flowing streams are obtained by using detectors coated with neutral n-alkanethiol monolayers. Permselective transport properties, based on solute polarity, are obtained and add a new dimension of information to amperometric detection. An elegant way of varying the transport properties of hydrophobic drugs and the exclusion of hydrophilic compounds is achieved by varying the chain length (i.e., hydrophobicity) of the n-alkanethiol modifier. The dynamic behavior of the detector is evaluated with respect to the thiol chain length or concentration, flow rate, solute concentration, and other variables. The surface coating, and hence the discriminative properties, are highly stable under the vigorous hydrodynamic conditions existing in the flow cell. Highly selective flow injection measurements of chlorpromazine in an untreated urine sample are illustrated. Copyright 1993, American Chemical Society. .
Chlorpromazine Organic compounds Hydrocarbons, aromatic Chlorpromazine Amperometry Self assembled monolayer

"Determination Of Urinary Albumin Using High Performance Immunoaffinity Chromatography And Flow Injection Analysis"
Anal. Chem. 1994 Volume 66, Issue 23 Pages 4265-4271
Peggy F. Ruhn, Jay D. Taylor, and David S. Hage

Abstract: The detection of low levels of albumin in urine can be an important aid in the early diagnosis of kidney disease. In this study, an automated system for urine analysis was developed that could simultaneously measure both albumin and creatinine, an indicator of urine output and volume. Albumin was determined by use of a column that contained immobilized anti-albumin antibodies. An online flow injection analysis system was used to measure creatinine as this solute eluted nonretained from the antibody column. The total analysis time of the system was 5 min per injection. Limits of detection for albumin and creatinine in a 20 µL sample (at S/N = 2) were 3 and 5 mg/L, respectively. The response for these compounds covered the range of clinical interest. Within-run precision for both analytes was±1-2% at normal urine concentrations. The results of this method showed good agreement with those obtained by reference techniques. This approach can be adapted for the detection of other urine components by changing the type of antibody column used in the system.
Albumin Creatinine LC Immunoassay Method comparison Immobilized antibody

"Automation Of Solvent Extraction Of Drugs In Continuous-flow Systems"
Fresenius J. Anal. Chem. 1981 Volume 305, Issue 4 Pages 277-284
Peter Neubert und Klaus Reiff

Abstract: The performance of liquid/liquid extractions in continuous flow-systems is described by means of two different fluorescent compounds. The conventional AutoAnalyzer-System (using air-segmentation) is compared with the Flow Injection Analysis (FIA)-method. The extractability of compounds from biological fluids is evaluated with regard to sampling rate, solvent and reagent requirements and to recovery depending on the kind of extraction used and on the protein content of the sample. An automated system for the extraction of drugs from serum and urine is described. It is intended to be a part of a fully automated system for sample preparation (extraction, change of solvent) for chromatographic analysis.
Drugs Clinical analysis Fluorescence Sample preparation Solvent extraction

"Determination Of Creatinine In Urine And Serum By Flow Injection Analysis Using The Jaffe Reaction"
Fresenius J. Anal. Chem. 1983 Volume 315, Issue 2 Pages 141-144
Jacobus F. van Staden

Abstract: A simple, modified, flow-injection procedure for the determination of creatinine in urine and deproteinized serum using the Jaffe reaction is described. The method is suitable for the flow-injection analysis of creatinine at a rate of up to 120 samples per hour with a coefficient of variation of better than 2.9%. The baseline drift is eliminated by the addition of 20% methanol to the picric acid solution.
Creatinine Clinical analysis Spectrophotometry

"Flow Injection System For The Determination Of Nickel By Means Of MIP OES After Conversion To Nickel Tetracarbonyl"
Fresenius J. Anal. Chem. 1989 Volume 332, Issue 8 Pages 862-865
W. Drews, G. Weber and G. T&ouml;lg

Abstract: The sample solution (100 µL) was mixed with streams of 40 mM HCl (4 mL min-1), 0.1 M NaOH containing 0.6% of NaBH4 for reduction of the sample to Ni0 (4 mL min-1), Ar (2 l h-1) and CO (150 mL h-1). After formation of Ni(CO)4 in a 13-turn glass reaction coil (coil diameter 2 cm; capillary i.d. 2 mm), the combined stream was passed through a gas - liquid separator (Broekaert and Leis, Ibid., 1980, 300, 22) with additional Ar (37 l h-1). The separated gas phase and O (800 mL h-1) were fed into a microwave-induced plasma for detection of Ni at 341.5 nm (input and reflected power 130 and 4 W, respectively; frequency 2.45 GHz). Calibration graphs were rectilinear from the detection limit (1 µg L-1 of Ni) to 100 µg l-1. In the determination of 10 µg L-1 the coefficient of variation was 2.2% (n = 10). The analysis rate was 120 h-1. There was no interference from a 4000-fold excess of Fe. The method was applied to water and urine samples. A flow injection - HPLC procedure for speciation of Ni in urine is also described.
Nickel Spectrophotometry Interferences Phase separator Glass Volatile generation Speciation

"Kinetic Determination Of Creatinine In Biological Fluids By Stopped-flow Injection Analysis"
Fresenius J. Anal. Chem. 1990 Volume 338, Issue 6 Pages 752-754
Beatriz Fern&aacute;ndez-Band, Pilar Linares, M. D. Luque de Castro and Miguel Valc&aacute;rcel

Abstract: Serum or diluted urine (130 µL) was injected into a 9 g L-1 NaCl solution and mixed partly along a 100-cm tube merging with the reagent stream. After a 25-cm reactor, the reacting plug reached the flow-cell, where the flow was halted 1 s after the residence time (delay time 28 s). A stop time of 35 s allowed the kinetic curve to be monitored at 500 nm. The pump was automatically started and the baseline was restored. All solution were kept at 25°C. The calibration graph was rectilinear from 3 to 150 µg mL-1 of creatinine. The coefficient of variation was 1.27% (n = 11). The kinetic measurements required no sample pre-treatment except for dilution of urine. The method compared favourably with the standard recommended procedure.
Creatinine Spectrophotometry Stopped-flow Flowcell Kinetic Calibration Dilution

"Flow Injection Determination Of Oxalate In Urine Based On An Inhibitory Effect"
Fresenius J. Anal. Chem. 1991 Volume 339, Issue 1 Pages 58-61
J. A. Infantes, M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: The method is based on the inhibitory effect of oxalate on the catalysis of H2O2 oxidation of 2,4-diaminophenol (I) by Fe(III). Thus, 0.1 M I is mixed with 1 M H2O2 - 1 M glycine buffer of pH 3.43, and sample mixed with 1 mM Fe(III) is injected into this stream. The mixture is passed through a reaction coil (350 or 50 cm), and detection is by measuring the absorbance decrease at 500 nm. For normal and stopped-flow methods, the calibration graphs were rectilnear for 0.2 to 12 and 0.2 to 40 µg mL-1, the precision was ±5.4% and ±3.5% (n = 11), and sampling rates of 30 and 20 h-1, respectively. Sample prep. was by the method of Archer et al. (Clin. Sci., 1958, 16, 405). Results for urine were good.
Oxalate Buffer Catalysis Stopped-flow

"Flame Atomic Absorption Spectrometric Determination Of Cadmium And Copper In Biological Reference Materials Using Online Sorbent Extraction Preconcentration"
Fresenius J. Anal. Chem. 1992 Volume 344, Issue 12 Pages 535-540
Shukun Xu, Michael Sperling and Bernhard Welz

Abstract: Animal or plant tissue reference material (0.5 g) was subjected to acid digestion and the residue was diluted with HNO3. Urine samples for analysis were diluted with water before addition of HNO3. The solution was loaded into a flow injection manifold where it was merged with a stream of 0.05% diethylammonium-NN-diethyldithiocarbamate. The complex formed was extracted online on a conical 100 µL micro-column of RP-C 18 sorbent and the chelates were eluted with methanol directly into the nebulizer - burner system of the spectrometer. Small air segments introduced before and after elution prevented the eluent from mixing with the sample solution and increased sensitivity. A sampling frequency of 85 h-1 was achieved, with a sample loading time of 30 s at a flow rate of 4.0 mL min-1. The enrichment factor for Cd and Cu was 20 and the detection limits were 0.15 and 0.2 µg L-1 for Cd and Cu, respectively. The coefficient of variation were 2.3% for 10 µL L-1 of Cd and 1.4% for 45 µg L-1 of Cu (n = 11). The procedure was suitable for the determination of Cu in biological materials and for Cd in urine. Low recoveries were obtained for Cd in samples containing high levels of Cu and/or Fe. Cadmium and copper at the µg/g to ng/g level in plant and animal tissue reference materials, and at the µg/L level in urine were determined by flame atomic absorption spectrometry using online sorbent extraction pre-concentration based on flow injection techniques. Bonded silica reversed phase sorbent with octadecyl functional groups (RP-C 18), packed in a 100 µL column, was used to collect the diethylammonium-N,N-diethyldithiocarbamate (DDTC) complex formed online in the sample digests at low pH. Methanol was used to elute the analyte chelates directly into the nebulizer-burner system of the spectrometer. Small air segments introduced before and after elution prevented the eluent from mixing with the sample solution and increased the sensitivity. A sampling frequency of 85/h could be obtained with a sample loading time of 30 s at a flow rate of 4.0 mL/min. The enrichment factor for both elements was 20 and the enhancement factors, including the effect of the organic solvent and with the flow spoiler removed, were 126 and 114 for cadmium and copper, respectively. The detection limits (3s) were 0.15 µg/L for cadmium and 0.2 µg/L for copper. The precision was 2.3% and 1.4% RSD for 10 µg/L Cd and 45 µg/L Cu, respectively. (n = 11). Results for the determination of cadmium and copper in various biological reference materials were typically in good agreement with certified values. Low recoveries were observed, however, for cadmium in samples containing high levels of copper and/or iron, such as bovine liver.
Cadmium Copper Sample preparation Spectrophotometry Sample preparation Reference material Air segmentation Preconcentration C18 Solid phase extraction

"Enzymatic Interference-free Assay For Oxalate In Urine"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 6 Pages 777-781
P. Ca&ntilde;izares and M. D. Luque de Castro

Abstract: A potentiometric method for the determination of oxalate in urine is proposed. It is based on the biochemical reaction catalyzed by oxalate decarboxylase/pervaporation/stopped-flow. The method affords a linear determination range between 0.03 and 0.08 mmol/l and has been successfully applied to the determination of oxalate in urine with excellent agreement of the results with those obtained by the conventional method based on precipitation/dissolution and titration. The effectiveness of the pervaporation process makes sample pretreatment other than dilution unnecessary. 16 References
Oxalate Potentiometry Stopped-flow Pervaporation Catalysis Method comparison Interferences Enzyme

"Determination Of Chromium(III) In Urine, Blood Serum, And Hair Using Flow Injection Chemiluminescence Analysis"
Fresenius J. Anal. Chem. 1998 Volume 361, Issue 5 Pages 509-511
R. Escobar, M. S. Garc&iacute;a-Dom&iacute;nguez, A. Guira&uacute;m, F. F. de la Rosa

Abstract: A flow injection (FI) chemiluminescence method for the determination of Cr(III) in blood serum, urine, and hair samples is reported. It is based on the chromium-catalyzed light emission from the luminol oxidation by H2O2. The app. consists of an FI system with a flow cell formed by a coiled transparent tube suitable for chemiluminescence detection. The specificity of the method is achieved in presence of EDTA. The detection limit under optimum conditions is 0.01 µg/L of Cr(III). Precision and accuracy were evaluated by determining Cr(III) concentrations in urine standards from the National Institute of Standard and Technol. (NIST).
Chromium(III) Chemiluminescence Indirect EDTA Optimization Reference material

"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 Spectrophotometry HPLC Speciation Preconcentration Solid phase extraction Silica C18 Pyrrolidine dithiocarbamate Heated reaction Post-column derivatization

"Flow Injection Analysis Of Zinc And Cobalt In Beverages, Biological, Environmental, And Pharmaceutical Samples"
Fresenius J. Anal. Chem. 1998 Volume 362, Issue 7-8 Pages 571-576
S. G. Aggarwal and K. S. Patel

Abstract: A new, simple, rapid, and selective flow injection analysis (FIA) method for the spectrophotometric quantification (speciation of inorganic and organic form) of Zn and Co with NH4SCN and malachite green (MG) in the presence of surfactants (CPC and TX-100) is described. The value of apparent molar absorptivity of the Zn- and Co-complexes are 1.23 x 104 and 8.67 x 103 L mol-1 cm-1 at absorption max., 635 nm, respectively. The detection limit (amt. causing a peak height >3 s) is 15 ppb Zn and 20 ppb Co, whereas their optimum working ranges for the quant. determinations are 0.05-2.0 ppm Zn and 0.07-2.5 ppm Co in the real samples. The sample throughput of the method is 120 samples/h at the flow rate of 5.0 mL/min with RSD of <1%. The method is free from interferences of almost all ions which are commonly associated with these metals in the complex materials. The composition of the complexes and their reaction mechanism involved are discussed. The effect of FIA and anal. variables for the determination of the metals are optimized. The method was applied to the quantification of Zn and Co in beverages, biol., environmental, and pharmaceutical samples.
Zinc Cobalt Spectrophotometry Speciation pH gradient Surfactant Interferences Complexation

"Determination Of Organolead Compounds And Of Chromate Beside Chromium(III)"
Microchim. Acta 1992 Volume 109, Issue 1-4 Pages 137-140
Bernd Neidhart and Christoph Tausch

Abstract: The pre-concentration. and determination of ionic alkyl-lead compounds in surface water and human urine and tetra-alkyl-lead compounds in ambient air are described. Preconcentration and cleanup steps were followed by HPLC separation. Ionic species were pre-concentrated by solid-phase extraction; detection was performed online. The alkyl-lead species were eluted from the HPLC column, partially de-alkylated by iodine solution to form dialkyl-lead species and detected as PAR [4-(2-pyridylazo)resorcinol] complexes after the reduction of excess iodine with thiosulfate and adjustment to pH 9 to 10. Difficulties in the validation of trimethyl-lead and dimethyl-lead in some matrices are discussed. A Cr(VI) speciation method consisting of selective biosampling using human erythrocytes and gas-furnace AAS and reversed flow injection analysis is described.
tetraalkyllead Chromium(VI) Spectrophotometry Reverse Speciation

"Spectral And Non-spectral Interferences In Inductively Coupled Plasma Mass Spectrometry"
Microchim. Acta 1995 Volume 119, Issue 3-4 Pages 277-286
Richard F. J. Dams, Jan Goossens and Luc Moens

Abstract: An overview is presented on the identification and elimination of interferences in ICP-MS. Elimination of spectral interferences by anion exchange, matrix modification and mathematical correction are discussed. Calibration methods, adapted sample preparations and flow injection techniques for the elimination of nonspectral interferences are then considered. Applications of the correction methods to the analysis of water, soil, sewage, urine, serum and wine are described. (50 references).
Mass spectrometry Sample preparation Interferences Matrix removal Review

"Speciation Of Mercury By Continuous-flow Liquid-liquid Extraction And Inductively Coupled Plasma Atomic-emission Spectrometry Detection"
Microchim. Acta 1996 Volume 122, Issue 3-4 Pages 157-166
A. Men&eacute;ndez Garc&iacute;a, M. L. Fern&aacute;ndez S&aacute;nchez, J. E. S&aacute;nchez Ur&iacute;a and A. Sanz Medel

Abstract: The method was based on continuous liquid-liquid extraction of methylmercury into xylene as its bromide followed by cold Hg-vapor hydride-generation ICP-AES. A diagram of the flow manifold is given. Sample of pH 6.5 (0.75 ml/min) was merged with 0.3 M KBr (0.5 ml/min) and passed through a mixing coil (100 cm) before merging with xylene (0.5 ml/min). After passage through an extraction coil (380 cm x 0.7 mm i.d.) the organic and aqueous phases were separated using a PTFE membrane. The organic phase merged with glacial acetic acid (1 ml/min) and 3.5% NaBH4 in DMF (0.7 ml/min) and the Hg vapor formed was transferred to the ICP in Ar (0.3 l/min) for determination of Hg by AES at 253.65 nm. The ICP parameters are tabulated. Inorganic Hg was determined in the aqueous phase by hydride-generation AES after acidification and reaction with 1% NaBH4. The detection limit for methylmercury was 4 ng/ml as Hg and that for inorganic Hg was 2 ng/ml. The calibration graph was linear up to 100 µg/ml methylmercury and the RSD for 100 ng/ml methylmercury (n = 10) was 5%. The sampling frequency was 10^-12/h. The method was applied to seawater and urine.
Mercury Methylmercury ion Spectrophotometry Sample preparation Speciation Solvent extraction Teflon membrane

"Correcting Measurement Errors Using Reference Materials In Method Validation"
Microchim. Acta 1996 Volume 123, Issue 1-4 Pages 231-240
Jytte Molin Christensen

Abstract: The correction of measurement errors in method evaluation studies is discussed. In the first example, reference materials were used in a method evaluation study of Pb in blood using two different AAS instruments (Perkin-Elmer Models 4100 and 5100) with Zeeman background correction. The number of method evaluation function (MEF) samples was insufficient for the MEF slopes to be used for correction of systematic errors. Secondly, a method evaluation study on valproate in plasma using an EMIT assay (SYVA) on a COBAS MIRA S is described; systematic error above 300 mM valproate was corrected for using the slope of the MEF. Thirdly, correction during evaluation of a FIA AAS method to determine As compounds and their metabolites in urine is described. The use of reference materials to determine performance characteristics during method development is discussed.
Lead Valproic acid Arsenic Spectrophotometry Reference material

"Continuous-flow Potentiometric Determination Of Creatinine In Urine With A Picrate-ion-selective Electrode"
Microchem. J. 1982 Volume 27, Issue 4 Pages 512-518
E. P. Diamandis and T. P. Hadjiioannou

Abstract: A completely automated potentiometric method for the determination of creatinine in urine is described. Creatinine reacts with picrate in alkaline media (Jaffe reaction) in a flow system, and the decrease in picrate activity is continuously monitored with a picrateselective flow-through electrode. Creatinine in urine, in the range 0.5-3 g/liter, was determined in a sample volume of 0.15 ml, with a relative standard deviation of about 1%. Forty samples per hour can be analyzed without previous dilution or pretreatment. Recovery of creatinine added to urine samples ranged from 90 to 111% with an average of 96.7%. The method compares favorably with a photometric method. The proposed automated method is suitable for routine clinical measurements and screening tests.
Creatinine Electrode Potentiometry

"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 Electrode Electrode Potentiometry Heated reaction

"Rapid Determinations Of Some 1,4-benzodiazepines By Flow Injection Analysis"
Microchem. J. 1988 Volume 37, Issue 3 Pages 257-262
D. Prada, E. Lorenzo, M. Hern&aacute;ndez and L. Hern&aacute;ndez*

Abstract: The inherent absorption properties of bromazepam, chlordiazepoxide and lorazepam were used in their determination in formulations and in urine, with a sampling rate capability of 120 h-1. Tablets were dissolved in methanol and the supernatant solution was diluted with 9 volume of 0.1 M acetate buffer (pH 4.5). Urine samples were buffered to pH 7.0 with phosphate solution and the drugs were extracted into ethyl ether. The ether solution was evaporated to dryness and the residue was dissolved in acetate buffer (pH 4.5) - methanol (9:1). Absorption max. were at 233 nm (bromazepam and lorazepam) and 244 nm (chlordiazepoxide). For determinations of 1.2 to 2.4 µg mL-1 of drug (n = 10), coefficient of variation were 2.0%.
Bromazepam Chlordiazepoxide Drugs Lorazepam Spectrophotometry Optimization

"Continuous-flow Analysis Of 3α-hydroxysteroids Using Immobilized 3α-hydroxysteroid Dehydrogenase"
Anal. Biochem. 1981 Volume 112, Issue 2 Pages 239-243
R. Bovara, G. Carrea, P. Cremonesi and G. Mazzola

Abstract: The 3-hydroxysteroid dehydrogenase from Pseudomonas testosteroni was coimmobilized with diaphorase on cellulose beads and used to prepare a continuous-flow µreactor. Thus it was possible to determine urinary and serum 3-OH steroids with spectrophotometric monitoring in the visible region. The increased stability of the enzymes following immobilization and the mechanical characteristics of the matrix made the reactor usable for at least 20 days. The assay speed was 10-15 samples per hour. The results obtained with immobilized enzymes followed closely those obtained with free 3-hydroxysteroid dehydrogenase. The method is sensitive, reliable, and economical.
3-α-Hydroxysteroids Immobilized enzyme

"Selective Determination Of Lithium In Biological Fluids Using Flow Injection Analysis"
Anal. Biochem. 1987 Volume 160, Issue 2 Pages 243-250
G. E. Pacey, Y. P. Wu and K. Sasaki

Abstract: The batch extraction of the cryptand 211 - Li - resazurin complex into 1,2-dichloroethane was carried out at 24°C for 10 min and the absorbance of the organic phase was measured at 630 nm. The chromogenic aza-12-crown-4 batch extraction of Li into CHCl3 was carried out at 24°C for 10 min and the absorbance of the organic phase was measured at 400 nm. Both systems were successfully automated by using a PTFE flow injection system (diagram presented). For the cryptand 211 - resazurin system with 1000 ppm of Na present the calibration graph was rectilinear for 0.7 to 2.1 ppm of Li for batch extraction (0.28 to 1.12 ppm for flow injection) and for the chromogenic aza-12-crown-4 system it was rectilinear for 0.3 to 2 ppm of Li (both methods). The methods were used in the determination of Li in serum and urine, with flow injection giving the better precision and accuracy. Good agreement was observed with known values and AAS results.
Lithium Spectrophotometry Method comparison Theory

"Determination Of Methylguanidine In Plasma And Urine By High Performance Liquid Chromatography With Fluorescence Detection Following Post-column Derivatization"
Anal. Biochem. 1990 Volume 184, Issue 2 Pages 213-218
Venkata K. Boppana*, Gerald R. Rhodes* and David P. Brooks

Abstract: Plasma (1 ml) was mixed with 0.2 µg of ethylguanidine as internal standard, adjusted to pH 11 with 26 µL of 1 M NaOH and applied to a 1 mL weak-cation-exchange extraction column, which was washed with water before elution with methanolic 1% trifluoroacetic acid. After evaporation under N, the residue was dissolved in 0.2 mL of the mobile phase [0.06 M chloroacetate buffer (pH 4.0) - methanol (17:3)], and a 0.1 mL portion was subjected to HPLC on an Ultrasil cation-exchange silica (10 µm) column (25 cm x 4.6 mm) at 60°C with a mobile phase flow rate of 0.75 mL min-1, post-column mixing at 70°C with NaOH and ninhydrin solution and fluorescence detection with a 470 nm cut-off filter (excitation at 390 nm). Urine was diluted tenfold with water before injection of a 20 µL portion. Calibration graphs were rectilinear for 1 to 1000 ng mL-1 of methylguanidine in plasma and 0.1 to 600 µg mL-1 in urine, and the detection limit was 100 pg. The intra- (n = 5) and inter-day (n = 15) coefficient of variation for 10, 100 and 1000 ng mL-1 of methylguanidine in plasma were 2.49, 1.30 and 1.38% and 7.51, 5.20 and 7.98%, respectively.
Methylguanidine HPLC Fluorescence Post-column derivatization Silica Detection limit

"Fluorometric Determination Of Urinary Kynurenic Acid By Flow Injection Analysis Equipped With A"
Anal. Biochem. 1990 Volume 190, Issue 1 Pages 88-91
Ken-ichi Mawatari, Fumio Iinuma and Mitsuo Watanabe

Abstract: A flow injection analysis involving a photochemical reaction and fluorometric detection has been developed for the determination of urinary kynurenic acid. Kynurenic acid was found to fluoresce on irradiation with ultraviolet light at pH 7.2 in the presence of hydrogen peroxide. This method was applied to flow injection analysis using a new procedure involving a 'bypass line' for the simultaneous determination of urinary kynurenic acid and background fluorescence. The calibration graph showed linearity over the range of 0.20 to 120 pmol. For pretreatment of urinary kynurenic acid, a PRE-SEP C18 cartridge was used. The mean recovery of kynurenic acid from urine was 94.5%. The content of urinary kynurenic acid was 13.0±2.68 µmol/day. There was good correlation (r = 0.9729) between values determined by flow injection analysis and high performance liquid chromatography. Urine, diluted 25-fold with 0.2 M Na2HPO4 - 0.1 M citric acid buffer (pH 3.2), was applied to a PRE-SEP C18 cartridge and kynurenic acid (I) was eluted with phosphate buffer solution (pH 7.2) containing 20% methanol. The eluate was subjected to flow injection analysis with 0.07 M phosphate buffer (pH 7.2) containing 25 mM H2O2 - methanol (8:2) as carrier solution (1.2 mL min-1). After injection into the carrier solution the stream was split; one part was passed through a photochemical reaction coil and the second part, for background correction, bypassed the reaction coil. Fluorescence detection was at 465 nm (excitation at 370 nm). The calibration graph was rectilinear for 0.20 to 120 pmol of I. Recovery was 94.5% and results correlated well (r = 0.973) with those by HPLC.
Kynurenic acid HPLC Fluorescence Photochemistry Calibration Dilution pH Method comparison

"A Flow Injection Biosensor System For The Amperometric Determination Of Creatinine: Simultaneous Compensation Of Endogenous Interferents"
Anal. Biochem. 1993 Volume 210, Issue 1 Pages 163-171
Rui C. S., Sonomoto K., Ogawa H. I. and Kato Y.

Abstract: Creatinine deaminase and L-glutamate oxidase were immobilized separately on propylamine - controlled pore glass with glutaraldehyde through a Schiff base, and glutamate dehydrogenase was coupled to succinate - controlled pore glass activated by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The two channel flow injection system (illustrated) comprised a peristaltic pump, injection valve, immobilized enzyme packed in a glass tube and a control tube of controlled pore glass with delay coil, a galvanic O electrode with flow cell, a potentiostat and a recorder. Urine samples were diluted (x 20) and portions (30 µL) were introduced into the system at a flow rate of 1.6 mL min-1. Double peak recording was obtained using the delay coil in one channel; one peak being creatinine, endogenous ammonia and glutamate, and the other being endogenous ammonia and glutamate. Calibration graphs were rectilinear from 0.1 (detection limit) to 2 mM creatinine with coefficient of variation of 2.3% (within-day; n = 12) and 3.9% (between-day; n = 8). Lower detection limits (~0.01 mM), suitable for creatinine determination in serum, were obtainable by increasing the injection volume, e.g., to 100 µL. A flow injection biosensor system was developed for the amperometric determination of creatinine based on coupled reactions of three sequentially aligned enzyme reactors, creatinine deiminase, glutamate dehydrogenase, and glutamate oxidase, using an oxygen electrode as the detector. To overcome the problem of endogenous ammonia and glutamate, the flow was split into two channels after the injector and rejoined before the glutamate dehydrogenase reactor. Double peak recording was obtained by setting a delay coil and a reference column in one of the two channels. The first peak gave the sum response of creatinine, endogenous ammonia, and glutamate, and the second that of endogenous ammonia and glutamate. By this method compensation for endogenous ammonia and glutamate, as well as for interfering ascorbic acid, was achieved simultaneously. The system gave linear calibrations up to 2 mM for the first peak and 3 mM for the second one. The lower detection limits were 0.1 and 0.02 mM for 35- and 100 µL injection of sample, respectively. One run was completed within 2 min. The system showed good reproducibility (<3%) and long operational stability (> 1300 runs). The assay results of creatinine in urine showed good correlation with those obtained from the chemical method of Jaffe.
Creatine Amperometry Sensor Kinetic Immobilized enzyme Interferences Controlled pore glass

"Amperometric Determination Of Galactose, Lactose And Dihydroxyacetone Using Galactose Oxidase In A Flow Injection System With Immobilized Enzyme Reactors And Online Dialysis"
Anal. Lett. 1985 Volume 18, Issue 7 Pages 871-889
Hans Lundb&#259;ck; Bo Olsson

Abstract: In the flow injection system (described in detail) the H2O2 produced by the action of galactose oxidase on the cited compounds is detected amperometrically via a mediator. The H2O2 is fed into a stream of K4Fe(CN)6 and this solution is passed through a bed of peroxidase and thence to the wall-jet amperometric detector. The system was used to determine lactose(I) in milk, D-galactose(II) in urine and dihydroxyacetone(III) in the presence of glycerol. The rectilinear ranges for these three determinations were 0.05 to 300 mM I, 2 µM to 60 mM II and 0 to 0.5 M III
Lactose Galactose dihydroxyacetone Amperometry Electrode Dialysis Immobilized enzyme

"Electrochemical Behaviour And Determination Of Nicardipine"
Anal. Lett. 1985 Volume 18, Issue 9 Pages 1087-1102
Wang, J.;Deshmukh, B.K.;Bonakdar, M.

Abstract: Cyclic voltammetry (5 mV s-1 scan rate, 50 mV amplitude) was used to characterize the electrochemical behavior of nicardipine(I) with vitreous-carbon, carbon-paste and hanging-mercury-drop electrodes. I was shown to be adsorbed on carbon electrodes with the surface species retaining its electroactive characteristics. This accumulation serves as a concentration step, improving the selectivity and sensitivity of the measurements. By removal of the electrode from the sample, after accumulation, and re-immersion in a second cell containing an electrolytic blank solution, interferences due to solution-phase electroactive compounds are eliminated and direct measurement is possible in urine. Differential pulse voltammetry at the mercury electrode permits determination of <1 µM-I with a detection limit of 20 nM. Amperometric detection for a flow injection system is shown.
Nicardipine Amperometry Electrode Electrode Electrode Voltammetry Voltammetry Interferences

"Bioluminescent Flow Sensors: L-alanine Determination In Serum And Urine"
Anal. Lett. 1987 Volume 20, Issue 8 Pages 1315-1330
Girotti, S.;Roda, A.;Piazzi, S.;Carrea, G.;Piacentini, A.L.;Angellotti, M.A.;Bovara, R.;Ghini, S.

Abstract: L-Alanine is determined by a bioluminescence continuous-flow technique based on its reaction with NAD+ catalyzed by L-alanine dehydrogenase(I). Urine samples are deproteinized and centrifuged and the supernatant solution are filtered. The filtrates are diluted with sodium pyrophosphate buffer (pH 9) before passage of portions, plus the buffer and 2 mM NAD+, through a nylon coil containing immobilized I. The bioluminescent solution [10 µM-flavine mononucleotide in 0.1 M potassium phosphate buffer (pH 6.9), 27 µM-decanal and 0.5 mM dithiothreitol] is added to the emergent solution, which then passes through a coil on which alkanal monooxygenase (FMN-linked) and NAD(P)H dehydrogenase (FMN) are immobilized. The bioluminescence is measured at 340 nm. The detection limit was 0.5 µM-L-alanine and response was rectlinear from 5 to 1500 pmol. Recovery was 94 to 108%. Serum samples are analyzed similarly but require only membrane filtration as pretreatment.
l-Alanine Bioluminescence Sensor Immobilized enzyme Nylon

"Dimethyldioctadecylammonium Chloride Bilayer Membrane Vesicle-enhanced And Manganese(II)-catalysed Chemiluminescence For Determination Of Adrenaline By A Flow Injection Method"
Anal. Lett. 1989 Volume 22, Issue 11&12 Pages 2445-2461
Matsue, K.;Yamada, M.;Suzuki, T.;Hobo, T.

Abstract: A batch and a flow injection system were used to measure the chemiluminescence produced when adrenaline (I) was oxidized by dissolved O in alkaline medium. In the optimized flow system, the carrier comprised aqueous 0.1 mM Mn(II) as catalyst, and after injection the stream was merged with aqueous 0.7 M NaOH and then with 3 mM dimethyldioctadecylammonium chloride to form bilayer membrane vesicles. The log. calibration graph was rectilinear from 10 nM to 0.1 mM I, and the coefficient of variation was 0.9% at 0.5 µM (n = 5). The sampling rate was 100 h-1. A sensitivity of 1 nM was attainable by the batch method, but the reproducibility was poor. The selectivity was good for I relative to catecholamines and their metabolites, but proteins and inorganic salts interfered seriously. The method is suitable for application to pharmaceutical formulations and, with appropriate sample pre-treatment, to urine.
Adrenaline Chemiluminescence Method comparison Optimization Interferences

"Fluorimetric Determination Of Mercury(II) Based On The Inhibition Of The Enzymic Activity Of Urease"
Anal. Lett. 1994 Volume 27, Issue 5 Pages 867-878
D. W. Bryce; J. M. Fern&aacute;ndez-Romero; M. D. Luque de Castro

Abstract: Urease was immobilized and stored at 4°C in 100 mM KH2PO4 buffer of pH 7. Glass tubes were packed with the support-enzyme conjugate. A urea solution was injected into a 5 mM phosphate buffer stream of pH 6.5, (0.7 ml/min) and passed through the enzymatic reactor (1 cm x 0.5 mm i.d.). The reaction plug then merged with the o-phthalaldehyde/N-acetyl-L-cysteine stream. Derivatization took place in an open reactor (400 cm) and was monitored at 458 nm (excitation at 340 nm). A schematic diagram of the flow manifold is given. For optimization of the inhibition process, the flow injection analysis variables were important, such as total flow rate, the flow rate of the sample and the time of sample loading. The calibration range was linear from 0.5-100 ng/ml of Hg2+. The RSD was 6.5% and the sampling frequency was 6 samples/h. The method cannot be applied to water analysis due to its low selectivity but it could be applied to special samples that do not contain Cu, Ni or Cd, or are present at such low concentrations as to cause no interference.
Mercury(II) Fluorescence Interferences Optimization

"Enzymic Assay Of Oxalate In Urine By Flow Injection Analysis Using Immobilized Oxalate Oxidase And Chemiluminescence Detection"
Anal. Lett. 1994 Volume 27, Issue 7 Pages 1239-1253
Hansen, E.H.;Winther, S.K.;Gundstrup, M.

Abstract: The FIA manifold (schematic diagram given) consisted of a peristaltic pump, propagating a carrier stream of 66 mM citric acid buffer of pH 3.5, into which a 50 µL sample was injected, and the reagent streams [luminol and hexacyanoferrate(III)] needed for the chemiluminescent determination of the H2O2 generated by the enzymatic conversion process in the immobilized oxalate oxidase reactor. L-Ascorbic acid at concentrations >2.5 mM was the only significant chemical interference. The elimination of this interference by addition of NaNO2 did not improve the selectivity of the approach. The method was used for urine analysis. The detection limit was 34 µM in undiluted urine. The method provides a convenient and rapid means of screening.
Oxalate Chemiluminescence Interferences Immobilized enzyme

"Flow Injection Spectrophotometric Determination Of Oxalate, Citrate And Tartrate Based On Photochemical Reactions"
Anal. Lett. 1998 Volume 31, Issue 8 Pages 1413-1427
Tom&aacute;s P&eacute;rez-Ruiz; Carmen Mart&iacute;nez Lozano; Virginia Tom&aacute;s; Antonio Sanz

Abstract: A flow injection configuration for the spectrophotometric determination of oxalate, citrate and tartrate is proposed. The procedure is based on the photochem. decomposition of the complexes formed between iron(III) and these anions. The iron(II) produced in the photochem. reactions was detected by measuring the absorbance after complexation with ferrozine (λmax=562 nm). Linear calibration graphs were obtained over the concentration. ranges 5.0 x 10^-6 - 1.0 x 10^-4 M, 8 x 10^-6 - 1.8 x 10^-4 M and 1.0 x 10^-6 - 2 x 10^-5 M for oxalate, citrate and tartrate, respectively. The relative standard deviations at the 1 x 10^-5 M concentration. level were within the range 1.29 - 1.47%. The sampling frequency was about 40 samples/h. The usefulness of the method was tested in the determination of oxalate in urine and spinach, of citrate in pharmaceuticals and soft drinks and of tartrate in pharmaceuticals. For the determination of oxalate in urine samples a prior separation of the analyte by precipitation with calcium chloride is recommended.
Oxalate Citrate Tartrate ion Spectrophotometry Photochemistry Complexation

"Flow Injection Determination Of Glucose By A Photoinduced Chemiluminescent Reaction"
Anal. Lett. 1998 Volume 31, Issue 11 Pages 1837-1855
Tomas Parez-R&uacute;z; Carmen Martinez-Lozano; Virginia Tomas; Antonio Sanz

Abstract: A flow injection procedure for the photochem. determination of glucose was developed. The method is based on the photooxidn. of glucose sensitized by 9,10-anthraquinone-2,6-disulfonate (disodium salt). The hydrogen peroxide formed in the photochem. reaction was measured by the chemiluminescent reaction with luminol and hematin. A linear calibration graph was obtained over the range 2.0 x 10^-6-8.5 x 10^-5 mol L-1. The method was applied to determining glucose in blood serum, urine and fruit juices.
Glucose Chemiluminescence Photochemistry

"Evaluation Of Electrodes Coated With Metal Hexacyanoferrate As Amperometric Sensors For Nonelectroactive Cations In Flow Systems"
Electroanalysis 1990 Volume 2, Issue 4 Pages 263-272
Karsten N. Thomsen, Richard P. Baldwin*

Abstract: Two electrodes modified with either nickel or cupric hexacyanoferrate films were evaluated and compared as sensors for nonelectroactive cations in a flow injection system. Both gave responses for group 1A and ammonium ions, but only the electrode modified with cupric hexacyanoferrate was sufficiently stable for use in flowing solutions. This electrode responded to K+, NH-4+, Rb+, and Cs+ ions rather selectively. Within this group, the selectivity could be controlled from general to almost specific toward Cs+ by the potential at which the electrode was poised. The electrode was compatible with a mobile phase of dilute nitric acid commonly used in ion chromatography, and chromatographic detection limits of 2 times 10^-7 M and linear responses over two decades were obtained. The electrode was applied to the ion chromatographic analysis of K+ and NH-4+ in urine and K+ in blood serum samples.
Potassium Ammonium Rubidium Cesium Amperometry Sensor HPIC

"Flow Injection Potentiomentric Determination Of Creatinine In Urine Using Sub-Nernstian Linear Response Range"
Electroanalysis 1993 Volume 5, Issue 2 Pages 113-120
Wojciech Matuszewski, Marek Trojanowicz, Mark E. Meyerhoff, Anna Moszczyska, Elzbieta Lange-Moroz

Abstract: The split-stream flow injection system is based on the use of a micro-reactor containing creatinine iminohydrolase immobilized on porous glass beads. Urine (20 µL) was injected into a carrier stream of water (2 mL min-1) and merged with 50 mM phosphate buffer (pH 7.0) containing 20 mM KCl and 40 mM NaCl. This stream was split into two channels; one was passed through a short length of tubing to a nonactin-based membrane electrode which detected NH4+ ions and the other flowed through the enzyme reactor followed by a longer tube as a delay loop prior to passing through the detector. The split sample zone and addition of alkali metal ions allowed simple correction for endogenous NH4+. A rectilinear response was obtained for creatinine, even up to 80 mM NH4+. Recoveries were >99% and the coefficient of variation (n = 10) were 1.48%.
Creatinine Potentiometry Electrode Cellulose nitrate Immobilized enzyme

"Continuous-flow And Flow Injection Stripping-voltammetric Determination Of Silver(I), Mercury(II) And Bismuth(III) At A Bulk Modified Graphite-tube Electrode"
Electroanalysis 1997 Volume 9, Issue 6 Pages 481-489
Ruidong Ye, Soo Beng Khoo*

Abstract: In continuous-flow analysis (CFA) sample solution [in 0.1 M acetate medium of pH 4.32, 0.1 M phosphate buffer of pH 5.5, and Britton-Robinson buffer of pH 3.8 for Ag(I), Hg(II), and Bi(III), respectively] was pumped through the flow cell for 10 min at 1.41 ml/min and accumulation was carried out under open circuit conditions. Then deaerated stripping solution [70 mM HCl, 75 mM KBr, 100 mM HNO3, and 1 M HCl for Ag(I), Hg(II), and Bi(III), respectively] was passed through the cell at 0.72 ml/min and after 15 s the appropriate deposition potential was applied [-0.15, -0.20, and -0.50 V (vs. Ag/AgCl) for Ag, Hg and Bi, respectively] for 15 s. Finally, differential-pulse anodic-stripping was carried out commencing at the deposition potential of the metal. For FIA (details given), the analysis was very similar and calibration graphs (CG) were linear for 5 nM- to 1 µM-Ag(I), 10 nM- to 2 µM-Hg(II) and 100 nM- to 5 µM-Bi(III). The respective detection limits (DL) were 0.18, 1.9 and 9.5 nM; RSD (n = 6) were 2.53-10.5, 2.57-5.77 and 5.97-7.9%, respectively. For FIA, CG were linear from 50 nM- to 5 µM-Ag(I), 100 nM- to 5 µM-Hg(II), and 5-50 µM-Bi(III), and the respective DL were 11, 20 and 1200 nM. RSD (n = 6) were 6.32, 6.44 and 7.9%, respectively.
Silver(I) Mercury(II) Bismuth(3+) Voltammetry Electrode Electrode

"Quantitative Liquid Chromatographic Determination Of Cefatrizine In Serum And Urine By Fluorescence Detection After Post-column Derivatization"
J. Chromatogr. A 1979 Volume 177, Issue 2 Pages 323-332
E. Crombez, G. van der Weken, W. van den Bossche and P. de Moerloose

Abstract: A fast, specific and sensitive high-performance liquid chromatographic procedure for the determination of cefatrizine, an orally active cephalosporin, in serum and urine is proposed. The drug is determined by the internal standard method, using cephradine as the internal standard. The separation is carried out on a reversed-phase column, filled with octadecylsilane chemically bonded microparticles. The eluent is a mixture of acetonitrile with 0.025 M sodium phosphate buffer (pH 7). Quantitation is effected by fluorescence detection of the fluorophores formed after post-column derivatization with fluorescamine in a packed-bed reactor. The chromatographic conditions and the conditions for the post-column derivatization are discussed. The method has been applied to serum and urine samples, which were analyzed after deproteinization with trichloroacetic acid and injection of the clear supernatant. The accuracy and reproducibility of the procedure were investigated by the determination of the cefatrizine content in spiked serum and urine samples.
Cefatrizine Fluorescence Post-column derivatization

"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 HPIC Fluorescence Amberlite Heated reaction Post-column derivatization

"Automated Analysis Of Mitomycin C In Body Fluids By High Performance Liquid Chromatography With Online Sample Pretreatment"
J. Chromatogr. A 1987 Volume 420, Issue 1 Pages 53-62
U. R. Tjaden, E. A. De Bruijn, R. A. M. Van Der Hoeven, C. Jol, J. Van Der Greef and H. Lingeman

Abstract: Plasma, ascites fluid and urine were pre-treated by dialysis across a cellulose membrane, followed by concentration. of the mitomycin(I)-containing acceptor stream on pre-columns (3 cm x 2 mm) of Polygosil C8 (40 to 63 µm). Pretreatment was fully automated by using continuous-flow and column-switching techniques. HPLC was carried out on a column (10 cm x 3 mm) of Nucleosil C8 (5 µm) with, as mobile phase, aqueous 15% acetonitrile, and detection at 360 nm. Up to 100 samples a day could be analyzed if two alternating pre-columns were used. The calibration graph was rectilinear from 5 to 200 ng mL-1 and was independent of the biological matrix. Within- and between-day coefficient of variation ranged from 4.4 to 2.9 and 5 to 11.3%, respectively, for plasma. Recoveries were 25% and the limit of determination was 0.5 to 1 ng mL-1. Floxuridine, fluorouracil, doxorubicin, vincristine and bleomycin did not interfere.
Mitomycin C HPLC Sample preparation Spectrophotometry Interferences Membrane Preconcentration Dialysis

"Liquid Chromatographic And Flow Injection Analysis Of Tetracycline Using Sensitized Europium(III) Luminescence Detection"
J. Chromatogr. B 1988 Volume 433, Issue 1 Pages 149-158
Thomas J. Wenzel, Lisa M. Collette, Deirdre T. Dahlen, Susan M. Hendrickson and Lawrence W. Yarmaloff

Abstract: Europium was used as a fluorophore for the detection of tetracycline(I) in HPLC and flow injection analysis. Gingival fluid was absorbed on filter-paper strips and tetracycline(I) was extracted with 1 mM Na2EDTA in 0.12 M KNO3 - acetonitrile (9:1). HPLC was performed on a column (25 cm x 4.6 mm) of C8 silica (10 µm). Various mobile phases and post-column reagent solution containing Eu(III) were evaluated; the fluorescence was detected at 616 nm (excitation at 392 nm). A 30 µs delay was incorporated in fluorescence measurement to avoid interference from fluorescent impurities. Detection limits were better than those obtained with UV detection. Europium (III) can be used as a luminescent chromophore for detection in the liquid chromatographic and flow injection analysis of tetracycline. Detection is dependent upon an intramolecular energy transfer from the tetracycline to Eu (III). In liquid chromatography, the Eu (III) is added post-column as a complex with ethylenediaminetetraacetic acid. The post-column phase also serves to adjust the pH for optimum sensitivity. The method is highly selective for tetracycline since few compounds are capable of transferring energy to Eu (III). Fluorescent impurities that would otherwise interfere in flow injection analysis can be eliminated through the use of a delay time between the source pulse and the start of data acquisition. The detection limits for tetracycline using sensitized Eu (III) luminescence are better than those obtained using ultraviolet detection. The method is applied to the analysis of tetracycline in urine, blood serum, and gingival crevice fluid.
Tetracycline HPLC Fluorescence Luminescence Complexation Interferences Post-column derivatization

"Online Sample Processing And Analysis Of Diol Compounds In Biological Fluids"
J. Chromatogr. A 1988 Volume 456, Issue 1 Pages 93-104
Karl-Siegfried Boos* and Bernd Wilmers, Eckhard Schlimme, Richard Sauerbrey

Abstract: A coupled dual-column system with optional post-column derivatization (illustrated) was used for online sample processing, trace enrichment and analysis for aromatic 1,2-diol and aliphatic cis-diol biomolecules. Catecholamines were determined in human urine acidified to pH 3.0 to 3.5 with 10 M HCl; noradrenaline and adrenaline were determined in plasma and serum treated with 10 M NaOH to pH 7 and ribonucleosides were determined in urine, serum and milk acidified to pH 4 with concentrated formic acid. Aliquots of the sample solution were applied to the HPLC system consisting of a pre-column and an analytical column. Catecholamines and ribonucleosides were detected by fluorescence and UV spectrometry, respectively. The pre-column packing, phenylboronic acid-modified silica (Hagemeier et al., Ibid., 1983, 268, 291), allowed simultaneous covalent affinity and size-exclusion chromatography.
Catecholamines Diols Ribonucleosides LC SEC Fluorescence Spectrophotometry Post-column derivatization

"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 HPIC Fluorescence Amberlite Heated reaction Post-column derivatization

"New Approaches To Coupling Flow Injection Analysis And High Performance Liquid Chromatography"
J. Chromatogr. A 1992 Volume 600, Issue 2 Pages 183-188
M. D. Luque de Castro* and M. Valc&aacute;rcel

Abstract: In pre-column arrangements (A), the flow injection system is placed before the LC column, whilst in post-column couplings (B), the chromatographic process takes place before the flow injection analysis. In each instance the downstream unit incorporates the detection module. Examples of the use of A include: the determination of Zn based on its activating effect on metal-free carboxypeptidase A immobilized in a controlled-pore-glass reactor; the coupling of a liquid - liquid extractor to a normal-phase chromatograph for the determination of caffeine in beverages and urine; and the coupling of an ultrasonic leaching cell for solid - liquid extraction processes such as in the determination of B in soil. Only those B systems incorporating two valves are considered to be true HPLC - flow injection analysis configurations. Examples of the use of B include: determination of aflatoxins in foodstuffs, based on enhancing their fluorescence by means of a redox reaction with Br; and the determination of bile acids, based on the production of NADH. A review with 15 references. An overview of the advantages gained in coupling a flow injection manifold to a liquid chromatograph is presented. Improvements in the analytical features arising from this association and the peculiar pre- and post-column arrangements are discussed, as are the promising prospects of arrangements to be developed for avoiding the preliminary steps of the analytical process.
Caffeine HPLC Post-column derivatization Pre-column derivatization Immobilized enzyme Controlled pore glass Review

"Determination Of BAY Y 3118, A Novel 4-quinolone, In Biological Fluids Using High Performance Liquid Chromatography And Photothermal Post-column Derivatization"
J. Chromatogr. B 1993 Volume 616, Issue 1 Pages 87-93
Hans Guenter Schaefer

Abstract: Plasma was diluted with 0.05 M H3PO4 and centrifuged; saliva and urine were diluted with 0.1 M phosphate buffer of pH 7.5. Portions of the resulting solution were injected on to a column (25 cm x 4.6 mm) of Nucleosil 100 C18 (5 µm) operated at 50°C and protected by a similarly packed guard column with acetonitrile/[0.1 M tetrabutylammonium bromide/0.05 M H3PO4 (1:1)] (19:81; pH 2) as mobile phase (1 ml/min). Post-column derivatization of the eluate was performed, utilizing either photolysis at 254 nm in a Beam Boost reaction unit or combined thermolysis and photolysis in a laboratory-made reactor (details given). Fluorimetric detection was performed, employing excitation at 277 nm and an emission cut-off filter (418 nm). Calibration graphs were rectilinear from 0.01-2.0 mg/l of BAY y 3118 (I) in plasma and 1-500 mg/l of I in urine. Intra- and inter-day RSD were from 3.3-5.1% and 2.6-9.8%, respectively, for plasma and from 0.5-3.8% and 2.5-6.9%, respectively, for urine. The method was used to determine the pharmacokinetic behavior of I in a healthy human volunteer. A reversed-phase high performance liquid chromatographic (HPLC) method that allows the sensitive and selective quantification of a novel 4-quinolone (BAY y 3118, I) in biological fluids is described. After sample dilution with 0.05 M phosphoric acid (plasma) or 0.1 M phosphate buffer pH 7.5 (urine), samples can be directly injected into the HPLC system. Prior to fluorescence detection, I is decomposed to fluorescence compound(s) by post-column derivatization utilizing either photolysis (Beam Boost reaction unit) or a combination of thermolysis and photolysis (laboratory-made post-column reactor). Compared with fluorescence detection alone, derivatization increases the signal intensity (about 80-fold) and the selectivity of the detection significantly. Concentrations down to 0.01 mg/l could be quantified in biological fluids. Only thermolysis was not able to decompose I to fluorescence products. Investigations on the stability of I in plasma and urine demonstrate good stability under the different conditions tested. The method was applied to human plasma and urine samples from a subject after a single oral dose of 100 mg of I.
4-Quinolone HPLC Fluorescence Post-column derivatization

"Analysis Of Oxazepam In Urine Using Solid-phase Extraction And High Performance Liquid Chromatography With Fluorescence Detection By Post-column Derivatization"
J. Chromatogr. A 1993 Volume 616, Issue 2 Pages 344-348
L. A. Berrueta, B. Gallo and F. Vicente

Abstract: Urine was hydrolyzed with β-glucuronidase (250 iu/ml) at pH 5 (adjusted with HCl) and 37°C for 24 h. The internal standard, nordiazepam (1 µg/ml) in 0.1 M KH2PO4/K2HPO4 buffer solution of pH 6 was added and the mixture was applied to a Bond-Elut C2 (100 mg) cartridge which was washed with aqueous 80% methanol. Elution was effected with aqueous 60% methanol, the eluate was evaporated to dryness and the residue dissolved in the mobile phase. The resulting solution was analyzed on a column (3.5 cm x 4.6 mm) of Ultrabase C18 with aqueous 60% methanol as mobile phase (0.5 ml/min) and post-column reaction with acetic acid at 100°C for fluorimetric detection at 469 nm (excitation at 364 nm). The calibration graph was rectilinear for 0.01-1 µg/ml of oxazepam; the detection limit was 4 ng/ml.of I. Recoveries were 95 and 97.9% at levels of 0.02 µg/ml and 0.2 µg/ml, respectively; corresponding RSD were 2.1 and 9.4%. A reversed-phase high performance liquid chromatographic method for oxazepam in human urine samples has been developed. The sample preparation consists of an enzymatic hydrolysis with β-glucuronidase, followed by a solid-phase extraction process using Bond-Elut C2 cartridges. The mobile phase used was a methanol-water (60:40, v/v) mixture at a flow-rate of 0.50 ml/min. The column was a 3.5 cm x 4.6 mm i.d. C18 reversed-phase column. The detection system was based on a fluorescence post-column derivatization of oxazepam in mixtures of methanol and acetic acid. A linear range from 0.01 to 1 µg/mL of urine and a limit of detection of 4 ng/mL of urine were attained. Within-day recoveries and reproducibilities from urine samples spiked with 0.2 and 0.02 µg/mL oxazepam were 97.9 and 95.0 and 2.1 and 9.4%, respectively.
Oxazepam HPLC Fluorescence Sample preparation Post-column derivatization

"Rapid And Sensitive Determination Of Nitrite In Foods And Biological Materials By Flow Injection Or High Performance Liquid Chromatography With Chemiluminescence Detection"
J. Chromatogr. A 1994 Volume 673, Issue 1 Pages 77-84
Nrisinha P. Sen*, Philander A. Baddoo and Stephen W. Seaman

Abstract: Cured meats and baby foods were homogenized, extracted with water, and the extract processed and filtered as described by Sen and Donaldson (cf. J. Assoc. Off. Anal. Chem., 1978, 61, 1389). Urine and saliva were analyzed directly. All samples were diluted (2-100 fold) with HPLC mobile phase. In the HPLC method, the sample (50-100 µL) was injected into a mobile phase (1 or 2 ml/min) of 0.05 M KH2PO4 of pH 6/5 mM tetrabutylammonium hydrogensulfate and passed through a column (25 cm x 4.6 mm i.d.) of Techsil C18 (5 µm). The nitrite-containing eluate was mixed with 10% H2SO4 in acetic acid and then with 10% KI (0.5 ml/min) and the solution was transported to a coiled PTFE tubing reactor kept at 70°C. Chemiluminescence detection of the NO thus formed was effected with a thermal energy analyzer.. The flow injection method was performed in the same way, but without the HPLC column. A diagram of the system used is given. The calibration graph was linear from 1-1000 ng of nitrite; the detection limit was 0.1 ng. The RSD (n = 4 or 5) was 0.2-4%. Recoveries were 92-108%.
Nitrite HPLC Chemiluminescence

"New Fluorimetric Determination Of 17-hydroxycorticosteroids After High Performance Liquid Chromatography Using Post-column Derivatization With Benzamidine"
J. Chromatogr. B 1984 Volume 305, Issue 1 Pages 188-193
Tokuichiro Seki and Yoshihisa Yamaguchi

Abstract: The method, which is more selective than HPLC with u.v. detection, could be used to determine urinary corticosteroids. A urine sample was treated with β-glucuronidase, 0.2 M phosphate buffer (pH 6.5) and CHCl3, and incubated for 24 h at 37°; the mixture was treated with β-methasone (internal standard) and CH2Cl2, and the washed organic phase was evaporated to dryness. Mobile phase (aqueous 50% methanol; 100 µL) was added to the residue, and 10 µL aliquots were injected into a column (25 cm x 4.6 mm) of Finepak C18 (10 µm) at 40°C (mobile-phase flow rate 0.8 mL min-1). The eluate was mixed with 0.4 M NaOH and 0.5% of benzamidine hydrochloride in aqueous 50% propan-2-ol, and the fluorescence was measured at 480 nm (excitation at 370 nm). The detection limit for hydrocortisone was 5 to 50 ng per injection. The within- and between-assay coefficient of variation were 2.4 and 5.2% and 3.2 and 7.8%, respectively, for the tetrahydro-derivatives of hydrocortisone and cortisone, respectively.
Corticosteroids, 17-hydroxy HPLC Fluorescence Post-column derivatization

"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 HPLC Fluorescence Heated reaction Post-column derivatization Glass beads

"Automated Determination Of Amoxycillin In Biological Fluids By Column Switching In Ion-pair Reversed-phase Liquid Chromatographic Systems With Post-column Derivatization"
J. Chromatogr. B 1985 Volume 344, Issue 1 Pages 285-296
Jan Carlqvist and Douglas Westerlund

Abstract: Plasma was deproteinized with HClO4 and buffered with citrate - phosphate buffer solution (pH 5.4) - 1 M NaOH (11:4) before analysis. Urine was adjusted to pH 4.85 with citrate - phosphate buffer solution before analysis. The chromatographic system comprised a guard column (5 mm x 4 mm) of Spherisorb S5 ODS (5 µm) and two analytical columns (10 cm x 4.6 mm) of CP Microspher C18 (3 µm) separated by a switching valve. Amoxycillin(I) was isolated on the first column with a mobile phase (0.75 mL min-1) of 10 to 11% of methanol in phosphate buffer solution (pH 7.4) containing 1 mM Na hexyl sulfate, and the eluate fraction containing I was transferred to the second column; I was eluted with a mobile phase (1 mL min-1) of 30 to 35% of methanol in phosphate buffer solution (pH 7.4) containing 1 mM tetrahexylammonium hydrogen sulfate. The eluate was mixed with fluorescein in acetonitrile before fluorimetric detection at 470 nm (372.5-nm excitation). The detection limits for I in plasma and urine were 10 and 25 ng mL-1, respectively, and the calibration graph was rectilinear for 0.05 to 75.2 µg mL-1 of I in urine.
Amoxycillin HPLC Fluorescence Post-column derivatization

"Measurement Of Labetalol By High Performance Liquid Chromatography With Electrochemical Detection"
J. Chromatogr. B 1985 Volume 344, Issue 1 Pages 412-415
Joseph Wang, Mojtaba Bonakdar and Balasaheb K. Deshmukh

Abstract: Urine was diluted with the mobile phase [acetonitrile - 0.05 M K2HPO4 buffer (pH 6; 7:13) containing Na2EDTA (0.2 g l-1)] and subjected to HPLC on a column (25 cm x 4.6 mm) of Biophase ODS (5 µm) with a mobile-phase flow rate of 1 mL min-1 and amperometric detection with a vitreous-carbon electrode at +0.9 to +0.95 V vs. silver - AgCl. The calibration graph was rectilinear for 5 to 30 ng of labetalol(I) and the detection limit was 0.6 ng injected. The coefficient of variation was 5%. The use of electrochemical detection in flow injection analysis for I is discussed.
Laβlol HPLC Electrode

"High Performance Liquid Chromatographic Determination Of β-aminoisobutyric Acid In The Picomole Range"
J. Chromatogr. B 1986 Volume 374, Issue 1 Pages 129-136
Frank L. Buschman, Gerald Apell and Opendra K. Sharma

Abstract: 3-Aminoisobutyric acid(I) was determined in serum and urine with or without hydrolysis of the sample (for total or free I, respectively). The HPLC was performed on a column (10 cm x 8 mm) of Radial-Pak C18 (5 µm) with 0.4 M Na citrate buffer of pH 4.2 as mobile phase (0.33 mL min-1) and fluorimetric detection at 410 nm (365-nm excitation) after post-column derivatization with phthalaldehyde. For the determination of total I in serum there was a preliminary clean-up by cation exchange on a column (30 cm x 3.9 mm) of W-3H resin to remove phenylalanine and tyrosine; I was eluted with 0.1 M NaH2PO4 buffer of pH 2.5. A rectilinear calibration graph was obtained for 5 pmol to 2 nmol of I.
3-Aminoisobutyric acid HPLC Fluorescence Post-column derivatization Sample pretreatment

"Rapid High Performance Liquid Chromatography Of 3-methylhistidine In Human Urine"
J. Chromatogr. B 1987 Volume 413, Issue 1 Pages 33-42
Paul E. Minkler, Stephen T. Ingalls, Ronda L. Griffin and Charles L. Hoppel

Abstract: Urine was mixed with 3-ethylhistidine (internal standard) and applied to a column (3 cm x 5 mm) of Dowex 50-X8 resin (200 to 400 mesh, pyridinium form). Elution was with aqueous 20% pyridine and the eluate was evaporated to dryness. The residue was dissolved in 0.085% H3PO4 and subjected to HPLC on a column (10 cm x 8 mm) of Radial-Pak C18 (5 µm) with a mobile phase and post-column derivatization as described previously (Ibid., 1986, 380, 285). Fluorimetric detection at 418 nm (excitation at 240 nm) was used. The between-sample, day-to-day and intra-assay coefficient of variation were 2, 2 to 5 and 1%, respectively, for the determination of 3-methylhistidine.
3-Methylhistidine HPLC Fluorescence Post-column derivatization

"Simultaneous Quantification Of Cycloserine And Its Prodrug Acetylacetonylcycloserine In Plasma And Urine By High Performance Liquid Chromatography Using Ultra-violet Absorbance And Fluorescence After Post-column Derivatization"
J. Chromatogr. B 1987 Volume 414, Issue 1 Pages 121-129
D. G. Musson, S. M. Maglietto, S. S. Hwang, D. Gravellese and W. F. Bayne

Abstract: Plasma was mixed with 0.2 M sodium borate buffer (pH 9.75), 6-aminohexanoic acid(I) (internal standard) and 5-methoxyindol-3-ylacetic acid (internal standard) and centrifuged. The supernatant solution was analyzed by HPLC. Urine was mixed with I, α-aminobutylhistidine and NaHCO3 and extracted with propan-2-ol. The organic phase was analyzed by HPLC. The HPLC was achieved on a column (24 cm x 5 mm) of ODS-Hypersil (10 µm) with a mobile phase (2.3 mL min-1) of propan-2-ol - water - concentrated acetic acid - decanesulfonate (pH 4.4) and post-column derivatization with phthalaldehyde - 2-mercaptoethanol. Detection was at 313 nm or fluorescent at 455 nm (excitation at 340 nm). The calibration graphs were rectilinear for 0.3 to 7.5 and 0.3 to 15.0 µg mL-1 of acetylacetonylcycloserine(II) and D-cycloserine(III), respectively, in plasma, and for 2.0 to 100.0 µg mL-1 of II or III in urine.
Pentizidone sodium Cycloserine HPLC Fluorescence Spectrophotometry Post-column derivatization

"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 HPLC Fluorescence Heated reaction Post-column derivatization

"Body Fluid Analysis Of A Phosphonic Acid Angiotensin-converting Enzyme Inhibitor Using High Performance Liquid Chromatography And Post-column Derivatization With Phthalaldehyde"
J. Chromatogr. B 1989 Volume 487, Issue 1 Pages 135-141
Harold Kadin, Harry G. Brittain, Eugene Ivashkiv and Allen I. Cohen

Abstract: Plasma or urine (1 ml) was mixed with 0.1 M Na acetate and a fluorinated analogue of the cited drug, i.e., 1- 6-amino-2-[hydroxy-(4-phenylbutyl)phosphinoyl]hexanoyl proline, as internal standard. The solution was applied to a column of C8 and elution was effected with methanol. After evaporation, the residue was dissolved in the mobile phase (200 µL). The solution was analyzed by HPLC on a column (15 cm x 4.1 mm) of PRP-1 (5 µm) with dilute H3PO4 as mobile phase (0.85 mL min-1). Post-column derivatization with phthalaldehyde was followed by fluorimetric detection at 418 nm (excitation at 229 nm). The calibration graphs were rectilinear from 0.2 to 10 µg mL-1 and 2 to 500 ng mL-1 for urine and plasma, respectively, with corresponding detection limits of 0.1 µg mL-1 and 1 ng mL-1.
Phosphoric acid HPLC Fluorescence Post-column derivatization

"High Performance Liquid Chromatographic Analysis Of Unchanged Cis-diamminedichloroplatinum (cisplatin) In Plasma And Urine With Post-column Derivatization"
J. Chromatogr. B 1990 Volume 529, Issue 1 Pages 462-467
Masafumi Kinoshita, Naomi Yoshimura and Hiroyasu Ogata, Daijiro Tsujino, Toshiaki Takahashi, Satoru Takahashi, Yuji Wada and Kazuhiko Someya, Tetsuro Ohno, Keisou Masuhara and Yoshio Tanaka

Abstract: Plasma was ultra-filtered and analyzed directly. Urine was centrifuged and diluted 1:10 before analysis. HPLC was carried out on a column (15 cm x 4.6 mm) of Hitachi No. 3013-N anion-exchange resin (5 µm), with a Guard-Pak CN pre-column and acetonitrile - 10 mM NaCl (17:3) as mobile phase (0.7 mL min-1). The eluate was mixed with 26 µM-K2Cr2O7 (0.14 mL min-1) and 6.6 mM NaHSO3 (0.7 mL min-1), and cisplatin was determined as Pt by AAS at 265.9 nm (heating program given). The limit of detection was 80 ng mL-1 and the calibration graph was rectilinear for 30 µg mL-1. Recovery was 95.0 to 104.0% from plasma and 98.0 to 103.8% from urine, with corresponding coefficient of variation of 4.9 to 7.9% and 3.0 to 5.5%. The method is applicable to pharmacokinetic studies.
HPLC Post-column derivatization Dilution Column Detection limit Calibration

"High Performance Liquid Chromatographic Determination Of Clenbuterol And Cimaterol Using Post-column Derivatization"
J. Chromatogr. B 1991 Volume 564, Issue 2 Pages 537-549
Dirk Courtheyn*, Carlo Desaever and Roland Verhe

Abstract: Animal tissues, faeces and feeding-stuffs were extracted with dilute 0.5 M HCl saturated with ethyl acetate; the resulting extracts or liquid samples, e.g., urine, plasma, blood and bile were purified on Chem Elut CE 120 columns and eluted with toluene - CH2Cl2. The eluate was mixed with 0.1 M HCl, ultrasonicated and centrifuged before a portion of the mixture was analyzed by HPLC on a column (15 cm x 4.6 mm) of Nova-Pak C18 (4 µm) with 25 mM sodium dodecyl sulfate and 0.02 M anhydrous acetic acid buffer of pH 3.5 containing 1 M NaOH - acetonitrile (53:47) as mobile phase (1.3 mL min-1). The eluate was derivatized with use of three reagents (details given) before the absorbance was measured at 537 and 493 nm for cimaterol and clenbuterol, respectively. Detection limits for liquid and solid samples were 0.1 ng mL-1 and 0.2 ng g-1, respectively. Results agreed well with those obtained by high performance TLC and GC - MS.
Cimaterol Clenbuterol HPLC Spectrophotometry Buffer Column Detection limit pH Post-column derivatization

"Determination Of Ampicillin In Biological Fluids By Coupled-column Liquid Chromatography And Post-column Derivatization"
J. Chromatogr. B 1991 Volume 567, Issue 1 Pages 121-128
K. Lanbeck-Vall&eacute;n*, J. Carlqvist and T. Nordgren

Abstract: Plasma (0.5 ml) was mixed vigorously with 70% trichloracetic acid in Na2PO4 - citric acid buffer solution, pH 5.4 (200 µL) and centrifuged at 2400 g for 10 min. A portion (400 µL) of the supernatant liquid was mixed with 1 M NaOH (85 µL) to adjust the pH to ~5. Paediatric plasma (100 µL) was treated in a similar manner. Urine was diluted with 0.5 M Na2PO4 - citric acid buffer solution of pH 4.85. Portions (20 to 100 µL) of the solution were analyzed by HPLC on a column of Perkin Elmer 3 x 3 (3 µm) connected in series with a column (10 cm x 4.6 mm) of Microspher C18 (3 µm) with elution (1 mL min-1) with 17% methanol in phosphate buffer solution of pH 7.4 containing 1 mM Na hexylsulfate for the first column and 35% methanol (for plasma) or 30% methanol (for urine) in phosphate buffer solution of pH 7.4 for the second column. The eluate from the second column was reacted with fluorescamine (0.16 mg mL-1) in acetonitrile and the fluorescence was measured at 470 nm (excitation at 372 nm). Detection limits were 14 nM and 570 nM-of ampicillin in plasma and urine, respectively.
Ampicillin HPLC Fluorescence Buffer Column pH Post-column derivatization

"Determination Of Neomycin In Plasma And Urine By High Performance Liquid Chromatography. Application To A Preliminary Pharmacokinetic Study"
J. Chromatogr. B 1991 Volume 571, Issue 1-2 Pages 189-198
Badar Shaikh*, Jean Jackson and Greg Guyer, William R. Ravis

Abstract: Plasma (1 ml) was deproteinized with 20% trichloroacetic acid solution and the solution was centrifuged. The urine sample was also centrifuged and both supernatant solution were analyzed on a column (15 cm x 4.6 mm) of Supelcosil LC-8-DB (5 µm). A guard column (2 cm x 4.6 mm) of LC-8-DB Supelguard was also used. The mobile phase consisted of 11 mM 1-pentanesulfonate, 56 mM Na2SO4, 7 mM acetic acid and 1.5% of methanol. Neomycin (I) was determined following post-column derivatization with phthalaldehyde at 33°C and fluorescence detection at 455 nm (excitation at 340 nm). Calibration graphs were rectilinear from 0.3 to 20 µg mL-1 of I. The average intra- and inter-assay coefficient of variation for I were 4.4 and 9.8%, respectively.
Neomycin B HPLC Fluorescence Column Kinetic Post-column derivatization

"Determination Of Aflatoxin Q1 In Urine By Automated Immunoaffinity Column Cleanup And Liquid Chromatography"
J. Chromatogr. B 1994 Volume 656, Issue 2 Pages 329-334
Anders Kussak, Barbro Andersson* and Kurt Andersson

Abstract: Urine (10 ml) was diluted with 10 mL of sodium acetate buffer of pH 5, spiked with 100 µL of a standard solution of aflatoxin M1, Q1 or P1, and added to an Aflaprep M column in a Millilab 1A workstation. The column was washed with water (10 mL at 2 ml/min), dried with N2 for 5 min at 100 kPa, washed with 25% THF in hexane (3 mL at 2 ml/min), dried again with N2, then the column was eluted with 1.5 mL of acetonitrile at 2 ml/min. The eluate was evaporated to dryness and the residue was dissolved in 200 µL of aqueous 50% acetonitrile. A portion (30 µL) was analyzed on a Nova-pak C18 (4 µm) column (10 cm x 5 mm i.d.), with aqueous 25% acetonitrile containing 1 mM KBr and 1 mM HNO3 as mobile phase (1 ml/min) and post-column derivatization in a PTFE tube (50 cm x 0.55 mm i.d.) for fluorimetric detection at 440 nm (excitation at 365 nm). Calibration graphs for the aflatoxin standards were linear in the range 1.25 (detection limit) to 16.9 ng/ml with 30 µL injections. Recoveries were 88%, 90% and 86% at 49.5, 146 and 305 pg/ml, respectively. The determination limit was 49.5 pg/ml.
Aflatoxins LC LC

"Determination Of Zuclopenthixol And Its Main N-dealkylated Metabolite In Biological Fluids Using High Performance Liquid Chromatography With Post-column Photochemical Derivatization And Fluorescence Detection"
J. Chromatogr. B 1994 Volume 658, Issue 2 Pages 319-325
Bodil Brandt Hansen and Steen Honor&eacute; Hansen

Abstract: The cis-isomer of clopenthixol (I; zuclopenthixol) and its main dealkyl metabolite (II) were extracted from plasma and urine by adsorption on to a Bond-Elut CN cartridge and eluted therefrom with acetonitrile/butylamine (9:1). Analysis was by HPLC on a Spherisorb S5 CN column (12 cm x 4.6 mm i.d.), operated at 40°C with 6 mM dodecyltrimethylammonium bromide in H2O/acetonitrile/0.2 M phosphate buffer of pH 6.5 (59:36:5) as mobile phase. Eluate was fed through a PTFE photochemical reactor coil (5 m x 0.5 mm i.d.) irradiated by a low-pressure 8 W mercury UV lamp and fluorimetric detection at 435 nm (excitation at 260 nm). The calibration graph was linear from 0.1-50 ng of I injected. Recoveries of 0.1-50 ng/ml of I and II were 62-79% and 82-89%, respectively and corresponding RSD (n = 6) were 7.2-16.6% and 5.8-12.5%. The limit of detection was 6 pg of I.
Zuclopenthixol N-dealkylzuclopenthixol HPLC Fluorescence Post-column derivatization UV reactor Photochemistry

"Determination Of Oxalate In Urine And Plasma Using Reversed-phase Ion-pair High Performance Liquid Chromatography With Tris(2,2'-bipyridyl)ruthenium(II)-electrogenerated Chemiluminescence Detection"
J. Chromatogr. B 1995 Volume 665, Issue 1 Pages 27-36
David R. Skotty and Timothy A. Nieman*

Abstract: Oxalate is quantitated in both urine and plasma samples using reversed- phase ion-pair high performance liquid chromatography (HPLC) with tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)2+(3)]-electrogenerated chemiluminescent (ECL) detection. Underivatized oxalate was separated on a reversed-phase column (Zorbax ODS) using a mobile phase of 10% methanol in 100 mM phosphate buffer at pH 7.0. The eluted compounds were combined with a stream of 2 mM Ru(bpy)2+(3) at a mixing tee before the ECL flow-cell. In the flow-cell, Ru(bpy)2+(3) is oxidized to Ru(bpy)3+(3) at a platinum electrode, and reacts with oxalate to produce chemiluminescence (CL). Urine samples were filtered and diluted prior to injection. Plasma samples were deproteinized before injection. A 25 µL aliquot of sample was injected for analysis. Possible interferants, including amino acids and indole-based compounds, present in biological samples were investigated. Without the separation, amino acids interfere by increasing the total observed CL intensity; this is expected because they give rise to CL emission on their own in reaction with Ru(bpy)3+(3). Indole compounds exhibit a unique interference by decreasing the CL signal when present with oxalate. Indoles inhibit their own CL emission at high concentrations. By use of the indicated HPLC separation, oxalate was adequately separated from both types of interferants, which thus had no effect on the oxalate signal. Urine samples were assayed by both HPLC and enzymatic tests, the two techniques giving similar results, differing only by 1%. Detection limits were determined to be below 1 µM (1 nmol/ml) or 25 pmol injected. The working curve for oxalate was linear throughout the entire clinical range in both urine and plasma.
Oxalate HPLC Chemiluminescence Interferences Post-column derivatization Indirect

"Immunoaffinity Column Clean-up For The High Performance Liquid Chromatographic Determination Of Aflatoxins B1, B2, G1, G2, M1 And Q1 In Urine"
J. Chromatogr. B 1995 Volume 672, Issue 2 Pages 253-259
Anders Kussak, Barbro Andersson* and Kurt Andersson

Abstract: A method for the determination of aflatoxins B1, B2, G1, G2, M1 and Q1 in human urine has been developed. The 10 mL urine samples were automatically cleaned up on immunoaffinity columns and analyzed by high performance liquid chromatography (HPLC), including post-column derivatization with bromine and fluorescence detection. Average aflatoxin recoveries were: B1 103%, B2 106%, G1 98% and G2 96% in the range 6.8-73 pg/ml of urine and M1 103% and Q1 100% in the range 18-97 pg/ml of urine. The relative standard deviations were all between 1% and 21%. The determination limits of aflatoxins in urine were 6.8 pg/ml for B1, B2, G1 and G2 and 18 pg/ml for M1 and Q1. (15 references)
Aflatoxin B1 Aflatoxin B2 Aflatoxin G1 Aflatoxin G2 Aflatoxin M1 Aflatoxin Q1 HPLC Fluorescence Post-column derivatization

"Development Of A Coupled-column Liquid Chromatographic-tandem Mass Spectrometric Method For The Direct Determination Of Betamethasone In Urine"
J. Chromatogr. B 1998 Volume 713, Issue 2 Pages 339-352
Aldo Polettini*, Giorgio Marrubini Bouland and Maria Montagna

Abstract: Different hyphenated liquid chromatography (LC) and mass spectrometric (MS) techniques were investigated to set-up a method for the fast, direct anal. of betamethasone in hydrolyzed and non-hydrolyzed urine using large-volume sample injection. After the optimization of the LC parameters using a traditional UV detector and of the thermospray and mass spectrometric parameters by flow injection, urine samples (0.5 mL) were submitted to anal. by either LC combined with tandem mass spectrometry (MS-MS), coupled-column LC (LC-LC) combined with single quadrupole MS, and LC-LC-MS-MS. Both the three-step configurations (LC-MS-MS and LC-LC-MS) did not provide satisfactory results: loss of sensitivity was noted in the case of LC-MS-MS (likely due to reduced efficiency in the ionization of betamethasone in the thermospray owing to the presence of large amounts of matrix interference), while in the case of LC-LC-MS a high chemical noise resulting in insufficient selectivity of detection was observed On the contrary, LC-LC-MS-MS anal. proved to meet the demand of high speed of anal. (sample throughput, 4.5 h-1), selectivity, and sensitivity (LOQ, 1 ng/mL; LOD, 0.2 ng/mL). Notwithstanding the complex anal. system adopted, the developed procedure was manageable and very robust, provided that at the beginning of each anal. session the performance of the system was controlled by checking the retention time of the analytes on the first anal. column with UV detection and by optimizing vaporizer temperature of the thermospray by flow injection.
Betamethasone Mass spectrometry HPLC Spectrophotometry Optimization Interferences

"Rapid Detection Of Dihydrocodeine By Thermospray Mass Spectrometry"
J. Chromatogr. B 1998 Volume 718, Issue 1 Pages 55-60
Manabu Yoshida*, Atsushi Akane, Yutaka Okii, Sumitaka Yoshimura, Takuma Tokiyasu and Toshimitsu Watabiki

Abstract: Rapid assay of dihydrocodeine (DHC) by thermospray mass spectrometry is explored. Liquid-liquid extractions of blood, urine and gastric contents were injected into a thermospray mass spectrometer, to which there was no column connected, and DHC was assayed by the flow injection method. The mass spectra of DHC under thermospray ionization and filament-on ionization modes consist of the MH+ ion of mlz 302 alone, which was clearly detected in the samples. Although DHC should be quantitated by gas chromatography-mass spectrometry, this method is applicable for rapid identification of DHC in biological materials.
Dihydrocodeine Mass spectrometry

"Direct Injection Of Plasma And Urine In Automated Analysis Of Catecholamines By Coupled-column Liquid Chromatography With Post-column Derivatization"
J. Pharm. Biomed. Anal. 1984 Volume 2, Issue 2 Pages 315-333
Per Olof Edlund* and Douglas Westerlund

Abstract: Adrenaline(I), noradrenaline(II) and dopamine(III) were selectively adsorbed from plasma on a column (1 cm x 4.6 mm) of benzeneboronic acid gel (Affi-Gel 601) or from urine on a column (2 cm x 3.8 mm) of dihydroxyboryl-silica or Aba-silica, and were eluted with aqueous H3PO4 containing 2 mM Na decyl sulfate(IV). The eluted catecholamines were enriched as ion pairs on a column (2 cm x 4.6 mm) of Supelcosil LC-18-DB (5 µm), before elution with methanol - buffer solution (1:4) and separation on a column (7.5 cm x 4.6 mm) of Supelcosil LC-18-DB (3 µm), with phosphate buffer (pH 6.65) - citrate buffer (pH 6.65) - methanol (3:3:2) (containing 2 mM (IV) and 0.3 mM EDTA) as the mobile phase (0.9 mL min-1). III was detected by coulometry at +0.3 V, and I and II by fluorimetry, as the trihydroxyindoles after post-column derivatization, at 510 nm (excitation at 400 nm). The limits of detection were 0.05, 0.04 and 1.6 pmol for I, II, and III, respectively, with coefficient of variation between 2 and 4%.
Adrenaline Noradrenaline Dopamine HPLC Fluorescence Coulometry Post-column derivatization

"Flow Injection Method For The Determination Of Oxalate In Urine Based On A Promoting Effect"
J. Pharm. Biomed. Anal. 1992 Volume 10, Issue 1 Pages 95-98
J. A. Infantes, M. D. Luque de Castro* and M. Valc&aacute;rcel

Abstract: Urine (5 ml) was adjusted to pH 5 to 5.2 with 2 mL of CaCl2 (5 g l-1), the mixture was set aside for 12 h and the calcium oxalate ppt. formed was separated off by centrifugation for 30 min. The ppt. was washed with dilute NH4OH, dissolved in 1 mL of 1N-H2SO4 and a portion of the solution was injected into a flow injection manifold (diagram given) into a stream of 1.4 mM Cr(VI) in 0.53 M H2SO4 which merged with a stream of 0.33 mM ferroin. The mixture was passed through a reaction coil (330 cm long) before the absorbance was measured at 510 nm. The calibration graph was rectilinear from 0.8 to 18 µg mL-1 of oxalate with a coefficient of variation (n = 11) of 2.81%; sampling frequency was 40 h-1. A simple, inexpensive and convenient method for the determination of oxalate in urine was developed. It is based on its promoting effect on the oxidation of ferroin by Cr(VI). It provided a wide linear determination range and acceptable precision and recovery. Its sampling rate makes it suitable for small and medium-sized labs.
Oxalate Spectrophotometry Linear dynamic range Low cost

"Flow Injection Spectrophotometric Determination Of Diclofenac Sodium In Pharmaceuticals And Urine Samples"
J. Pharm. Biomed. Anal. 1998 Volume 17, Issue 2 Pages 267-273
M. Soledad Garc&iacute;a, M. Isabel Albero, Concepci&oacute;n S&aacute;nchez-Pedre&ntilde;o* and Jos&eacute; Molina

Abstract: A fast and sensitive flow injection spectrophotometric method for the determination of diclofenac sodium based on the formation of colored compound with Ce(IV) ammonium nitrate and 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in 3 x 10^-2 M H2SO4 medium is presented. Using the peak height as a quant. parameter, diclofenac was determined at 580 nm over the concentration. range of 0.20-8.0 µg/mL. The proposed method was applied to the determination of diclofenac in pharmaceutical preparations and urine samples.
Diclofenac Spectrophotometry

"Urea Potentiometric Biosensor Based On All-solid-state Technology"
Sens. Actuat. B 1993 Volume 16, Issue 1-3 Pages 448-452
D. Martorell, E. Mart&iacute;nez-F&aacute;bregas, J. Bartrol&iacute; and S. Alegret, C. Tran-Minh

Abstract: All-solid-state electrodes (without an internal contact solution), were constructed using a procedure which permitted the implementation of transducers in various configurations (cf., Biosensors Bioelectron. 1989, 4, 287). The transducers consisted of ammonium-selective PVC membranes applied directly on to conductive composite materials, e.g. graphite/epoxy composites. Urease was immobilized on to the PVC membranes, using the procedure of Kurmaran et al. (cf., Anal. Chem., 1991, 63, 1914) which allowed the deposition of an extremely thin layer of reticulated enzyme (1-2 µm) by means of an aerosol-spraying procedure. The resulting urea potentiometric biosensors exhibited a short response time (10 s) and a wide linear range (0.01-1 mM urea) with a sensitivity of 55 mV/decade. The lifetime of the sensor was ~40 days in periodical calibration use. A flow-through biosensor was also constructed using the same type of transducer and the same enzyme immobilization procedure for use in a FIA system. Using the flow-through sensor for the determination of 0.1 mM urea resulted in an RSD (n = 20) of 0.4%.
Urea Potentiometry Electrode Sensor Electrode Electrode Apparatus Detector

"Determination Of Selenium In Urine By Flow Injection Hydride Generation Electrothermal Atomic Absorption Spectrometry With In-atomizer Trapping"
Spectrochim. Acta B 1997 Volume 52, Issue 12 Pages 1773-1781
Julian F. Tysona,*, Nils G. Sundina, Christopher P. Hannab and Susan A. McIntoshb

Abstract: Following digestion of the sample in a mixture of bromate and hydrobromic acid, the inorganic selenium produced was quantified by trapping hydrogen selenide, formed when a 500 µL sample volume injected into a hydrochloric acid carrier stream merged with a stream of sodium borohydride solution, on the iridium-pretreated interior of a graphite furnace atomizer. A number of parameters relating to the digestion, flow injection manifold and trapping in the atomizer were investigated, including a study of factors affecting the detection limit. It was found necessary to heat the digest under reflux at a temperature of 150°C for 2 h. Quantitative recoveries, from a human urine matrix, of selenite, selenate, trimethylselenium, selenocystine, selenopurine and selenomethionine spikes were obtained. The efficiency of hydride generation, transport and trapping was 75%. The major factors affecting the detection limit were the reagent purity and the volume injected. For high-purity hydrobromic acid and borohydride free of caking agent, the detection limit, based on three times the standard deviation of the blank, was 0.06 µg L-1 for a 1000 µL injection volume corresponding to a detection limit of 3 µg L-1 for a urine sample. The method was validated by the accurate analyzes of Standard Reference Material 2670 from the National Institute of Standards and Technology, and urine samples from an interlaboratory comparison program. The procedure avoids the need for perchloric acid and produces selenium in the + 4 oxidation state and thus no reduction is needed prior to generation of the hydrogen selenide. The use of a graphite furnace atomizer avoids the need for frequent reconditioning of the atomizer surface and the need for the standard additions method, both of which are drawbacks of procedures which make use of the quartz tube atomizer. All sample handling procedures following the digestion were automated by the use of flow injection technology.
Selenium Spectrophotometry Sample preparation Reference material Standard additions calibration

"Determination Of Heavy Metals By Inductively Coupled Plasma Mass Spectrometry After Online Separation And Preconcentration"
Spectrochim. Acta B 1998 Volume 53, Issue 11 Pages 1527-1539
Valderi L. Dressler, Dirce Pozebon and Adilson J. Curtius*

Abstract: A method for the determination of Cu, As, Se, Cd, In, Hg, Tl, Pb and Bi in waters and in biological materials by inductively coupled plasma mass spectrometry, after an online separation, is described. The matrix separation and analyte pre-concentration is accomplished by retention of the analytes complexed with the ammonium salt of O,O-di-Et dithiophosphoric acid in a HNO3 solution on C18 immobilized on silica in a minicolumn. Methanol, as eluent, is introduced in the conventional pneumatic nebulizer of the instrument. To use the best compromise conditions, concerning the ligand and acid concentrations, the analytes were determined in two sep. groups. The enrichment factors were at 5-61, depending on the analyte. The limits of detection varied from 0.43 ng L-1 for Bi to 33 ng L-1 for Cu. The sample consumption is only 2.3 mL for each group and the sampling frequency is 21 h-1. The accuracy was tested by analyzing five certified reference materials: water, riverine water, urine, bovine muscle and bovine liver. The agreement between obtained and certified concentrations was very good, except for As. The relatively small volume of methanol, used as eluent, minimizes the problems produced by the introduction of organic solvent into the plasma.
Metals, heavy Copper Arsenic Selenium Cadmium Indium Mercury Thallium Lead Bismuth Mass spectrometry Interferences Method comparison Reference material Preconcentration C18 Silica Ion pair formation

"One-Shot Flow Injection Analysis With Immobilized Enzyme Columns: Clinical Applications"
Anal. Sci. 1987 Volume 3, Issue 3 Pages 277-278
M. OHYABU, M. FUJIMURA, K. TANIMIZU, Y. OKUNO, M. TABATA, M. TOTANI and T. MURACH

Abstract: A flow injection system is described (with diagrams) for the determination of glucose, lactic acid, uric acid and urea-N in serum, plasma or urine. Detection is by chemiluminescence at 425 nm after reaction of enzymatically formed H2O2 with luminol.
Glucose Lactic acid Uric acid Nitrogen, urea Clinical analysis Chemiluminescence Apparatus Immobilized enzyme Review Column

"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 HPLC Fluorescence Post-column derivatization Heated reaction

"Flow Injection Determination Of Trace Amounts Of Hydrogen Peroxide With Thio-Michler's Ketone"
Anal. Sci. 1990 Volume 6, Issue 7 Pages 149-150
K. TOEI, T. TAMARU and M. ZENKI

Abstract: Samples (0.13 ml), containing 0.02 to 1 ppm of H2O2, are injected into a carrier stream comprising 25 mM NaI - 0.5 mM ammonium molybdate - 0.2% of Na polystyrene sulfate. This is mixed with a reagent solution comprising 45 µM-4,4'-bis(dimethylamino)thiobenzophenone (I) - 1.3% of Triton X-100 - 13% of methoxyethanol - 0.05 M formate buffer (pH 3.5) in a reaction coil maintained at 30°C. The color change of I (thio-Michler ketone) is measured at 660 nm. Samples could be analyzed at a rate of 42 h-1. The calibration graph was rectilinear over the cited range. The system could be used to determine glucose indirectly, by incorporation of glucose oxidase. The calibration graph was rectilinear for 80 mg l-1. The method was used to determine glucose in urine. Samples (0.13 ml), containing 0.02 to 1 ppm of H2O2, are injected into a carrier stream comprising 25 mM NaI - 0.5 mM ammonium molybdate - 0.2% of Na polystyrene sulfate. This is mixed with a reagent solution comprising 45 µM 4,4'-bis(dimethylamino)thiobenzophenone (I) - 1.3% of Triton X-100 - 13% of methoxyethanol - 0.05 M formate buffer (pH 3.5) in a reaction coil maintained at 30°C. The color change of I (thio-Michler ketone) is measured at 660 nm. Samples could be analyzed at a rate of 42 h-1. The calibration graph was rectilinear over the cited range. The system could be used to determine glucose indirectly, by incorporation of glucose oxidase. The calibration graph was rectilinear for 80 mg l-1. The method was used to determine glucose in urine.
Hydrogen peroxide Glucose Spectrophotometry Triton X Buffer pH Calibration Enzyme Surfactant

"Spectrophotometric Determination Of Protein With Chromazurol B - Beryllium(II) Complex By Manual And Flow Injection Methods"
Anal. Sci. 1992 Volume 8, Issue 3 Pages 313-316
Y. FUJITA, I. MORI and M. TOYODA

Abstract: For the manual method, 1.0% Triton X-405, 0.1 M EDTA, 0.2 M acetate buffer (pH 4.5), 0.5 mM Be(II) and 0.5 mM Chromazurol B (C. I. Mordant Blue 1) and a solution containing ~150 µg of human serum albumin (I) were mixed. After dilution the absorbance was measured at 625 nm. For the flow injection method (diagram shown) the carrier solution was 30 mM acetate buffer (pH 4.5) containing 0.05 mM Be(II), 0.05 mM Chromazurol B, 5.0 mM EDTA and 0.05% Triton X-405. The concentration. of I was from 10 to 100 µg mL-1. The reaction coil was 6 m long and the flow rate was 1.5 mL min-1. For the manual method, Beer's law was obeyed up to 15 µg mL-1 of I with a coefficient of variation at 7.5 µg mL-1 (n = 10) of 0.93%. For the flow injection method the calibration graph was rectilinear from 0.01 to 0.1 µg µL-1 injected. The coefficient of variation for 0.4 µg-I in 10 µL injected was 1.38% (n = 10) and the injection rate was 90 h-1. The manual method was three times more sensitive than the Pyrogallol red - Mo(VI) test kit (Wako, Japan). A spectrophotometric study of protein/Chromazurol B/beryllium(II) system is reported. In the manual spectrophotometric method, Beer's law is obeyed for protein (as human serum albumin, HSA) concentrations. up to 150 µg/10 mL. This procedure is about 3 times more sensitive than the Pyrogallol Red-molybdenum(VI) method. In the flow injection method which employs a single-channel flow manifold system, the calibration graph is linear for the HSA range from 0.1 to 1 µg/10 µL by direct injection. Results obtained by the present manual method and the Pyrogallol Red-molybdenum(VI) method agree with each other in the determination of urinary proteins. No significant difference in results was observed between the manual and flow injection methods.
Protein Spectrophotometry Method comparison Triton X Surfactant

"High Performance Liquid Chromatographic Determination Of Total Catecholamines And Metabolites In Human Urine By Application Of The Fluorescence Derivatization Method For Their Free Form"
Anal. Sci. 1993 Volume 9, Issue 4 Pages 537-540
H. NOHTA, H.-K. JEON, M. KAI and Y. OHKURA

Abstract: Urine was hydrolyzed with 1 M HClO4, 30 mM Na2EDTA and 0.1 M reduced glutathione at 100°C for 20 min to determine the total amino-compounds (TAC) and for 50 min to determine the total acidic and alcoholic compounds (TAAC). The internal standard, 30 µM isoproterenol was added prior to hydrolysis for TAC and after for TAAC, which after clarification (described), were separated by HPLC (cf. Anal. Biochem., 1992, 200, 332) and identified by post-column derivatization using periodate oxidation followed by fluorescence detection with meso-1,2-diphenylethylenediamine. Calibration graphs were linear from 10^-3000 pmol of vanillylmandelic acid and 4-hydroxy-3-methoxyphenylethylene glycol (I), and from 0.2-200 pmol of norepinephrine (II), epinephrine, dopamine, normetanephrine, metanephrine, 3-methoxytyramine, 3,4-dihydroxyphenylacetic acid, and homovanillic acid. The corresponding detection limits were 60, 90, 0.3, 0.7, 2, 0.4, 1, 2, 5, and 5 pmol/ml, in urine. The RSD were 4.5 and 5% for I and II, respectively, and 3% for all the others.
Epinephrine Norepinephrine Dopamine Normetanephrine Vanillylmandelic acid 4-Hydroxy-3-methoxyphenethylene glycol Metanephrine 3-Methoxytyramine 3,4-dihydroxyphenylacetic acid Homovanillic acid Fluorescence HPLC Post-column derivatization

"Quantification Of Histamine By Post-column Fluorescence Detection High Performance Liquid Chromatography Using Orthophthalaldehyde In Tetrahydrofuran And Reaction Mechanism"
Anal. Sci. 1994 Volume 10, Issue 2 Pages 259-265
K. KURUMA, E. HIRAI, K. UCHIDA, J. KIKUCHI and Y. TERUI

Abstract: Serum (1 ml) was mixed with 0.6 mL of 10% trichloroacetic acid and centrifuged for 2 min at 10 500 g and 0.1 mL of the supernatant solution was analyzed by HPLC. Urine was diluted tenfold with water and a 0.1 mL portion was analyzed by HPLC. Both were analyzed on a column (15 cm x 6 mm i.d.) of TSKgel Catecholpak at 40°C with a mobile phase (1 ml/min) of 0.2 M propionate buffer of pH 4.5 containing 86 mM NaCl. For post-column derivatization the eluate was mixed with a 0.1% orthophthalaldehyde solution in THF (0.6 ml/min) at 40°C with fluorescence detection at 430 nm (excitation at 360 nm). The calibration graph was linear for 10^-1280 pg of histamine with a detection limit of 5 pg and RSD (n = 9) of 3.2-4.5%. Recoveries of 7-110 nM-histamine in serum were 104-114% with intra-day and inter-day RSD (n = 5) of 0.8 and 3.3%, respectively, for 27.8 nM-histamine. In urine recoveries were 99-102% for 170-2780 nM-histamine with intra- and inter-day RSD (n =5) of 0.9 and 2%, respectively, for 694 nM-histamine. Reaction mechanism studies are also presented.
Histamine HPLC Fluorescence Post-column derivatization

"Kinetic Determination Of Uric Acid In Urine Based On Single-line Flow-system With Multi-site Detection"
Anal. Sci. 1998 Volume 14, Issue 4 Pages 809-813
Alberto N. Ara&uacute;jo, Jos&eacute; A. M. CATITA and Jos&eacute; L. F. C. LIMA

Abstract: A flow injection system based on multi-site detection for kinetic spectrophotometric determination of uric acid in urine is described. The system was studied regarding phys. dispersion, elimination of sample matrix interferences and applicability to real samples. In the optimized system, the sample is inserted into a water stream which merged downstream with the reagent solution containing iron(II) chloride and TPTZ. This system enables the determination of about 30 samples/h, and yields precise results (RSD usually <2.9%). Sensitivity is 212 mAU l/mmol up to 0.60 mmol/l uric acid. Accuracy was assessed by running 32 samples already analyzed by a conventional enzymatic procedure. No statistical difference between methods was found at the 95% confidence level.
Uric acid Kinetic Interferences Optimization Method comparison Multidetection

"New Chemiluminescence Reaction System For Analysis Of Polyhydroxy-compounds Determination Of Uric-acid In Urine"
Acta Chim. Sin. 1997 Volume 55, Issue 8 Pages 806-810
FENG MANLIANG;HUANG YUWEN;ZHANG ZHUJUN

Abstract: A novel flow injection chemiluminescence method for the determination of polyhydroxy - compounds was described. The method is based on that polyhydroxy - compounds enhance the CL reaction of luminol with K-7 in potassium hydroxide medium. In the experiments, luminescent reagent-luminol was injected in order to keep the baseline steady and save reagents,especially,to improve sensitivity. The method was used in measuring uric acid in urine and it allows quantitation of uric acid concentration in the 2 x 10^-8 similar to 1 x 10^-6 g/mL range with a detection limit of 7.2 x 10^-9 g/mL. RSD = 2.04%. 8 References
Uric acid Chemiluminescence Sensitivity

"Analysis Of Penicillins In Biological Material By Reversed-phase Liquid Chromatography And Post-column Derivatization"
Acta Pharm. Suec. 1979 Volume 16, Issue 3 Pages 187-214
Westerlund D, Carlqvist J, Theodorsen A.

Abstract: The procedure comprises injection of the biological fluid or homogenate after protein precipitation, separation by reversed phase liquid chromatography (LiChrosorb RP 8), post-column derivatization with air-segmentation and finally detection of the UV-absorbance at 310 nm. The derivatization involves formation of the mercuric mercaptide of penicillenic acid and is specific for penicillins with an intact ring system. The conditions for liquid chromatography and derivatization are optimized for the determination of ampicillin [69-53-4] and mecillinam [32887-01-7], but the method is general and may be adapted to any penicillin [1406-05-9] or cephalosporin [11111-12-9]. The influence of pH and MeOH content of mobile phase was systematically studied. By the injection of 100 mL plasma, ampicillin and mecillinam can be quant. determined at 100 ng/mL with a precision of 8%, but the sensitivity increases in direct proportion to the injected volume up to 2 mL. The method was applied to determinations in plasma, whole blood, urine and lymph.
Penicillins HPLC Spectrophotometry Post-column derivatization Optimization

"Flow Injection Chemiluminescence Determination Of Imipramine And Chlorpromazine"
Anal. Commun. 1996 Volume 33, Issue 1 Pages 31-33
J. L. Lopez Paz and Alan Townshend

Abstract: Analysis was carried out in a flow system (diagram given) consisting of a peristaltic pump, injection valve, mixing piece, flow coil and photomultiplier tube. Drug solutions were injected in to a 2 M H2SO4 stream which mixed with a 4 M KMnO4/2 M H2SO4 stream; flow rates were 1.74 ml/min. The peak height of the emission response was measured. This technique was simple and rapid, 85 and 100 samples/h for imipramine and chlorpromazine, respectively. RSD were 1% and 1.2% (n = 8) for 10 µM-imipramine and 25 µM-chlorpromazine, respectively; corresponding detection limits were 50 µM and 20 µM. The method was applied to the analysis of urine. Recoveries were 103.5% and 99.2% for imipramine and chlorpromazine, respectively; RSD was 4%.
Imipramine Chlorpromazine Chemiluminescence

"Post-column Derivatization Of Sugars By Liquid Chromatography"
Analusis 1979 Volume 7, Issue 7-8 Pages 381-385
Suon, K.N.;Vialle, J.;Rocca, J.L.

Abstract: Post-column derivatization using tetrazolium blue was shown for liquid chromatography detection of sugars. Sepns. were performed on Lichrosorb NH2 (10 mm) as the stationary phase and water-acetonitrile mixture as the mobile phase. This post-column derivatization is discussed with respect to peak area (reaction kinetics) and peak height (detection sensitivity). Post-column addition of derivatization reagent resulted in peak broadening; this effect could be reduced by using the lowest flow-rates ratio between reagent and mobile phase. Capillary tube length also acts on derivative quantity and on dilution Conditions permitting complete derivatization did not always resulting in the best detection limits. This post-column derivatization mode was used in the direct liquid chromatography anal. of urine. (SFS)
Sugars Spectrophotometry Post-column derivatization Optimization

"Development Of A Simple, Low-cost, Continuous-flow System For The Automated Radio-immunoassay Of Steroid Glucuronides"
Ann. Clin. Biochem. 1983 Volume 20, Issue 5 Pages 294-301
Barnard GJ, Collins WP.

Abstract: An auto-analyzer system (ChemLab Instruments Ltd., Hornchurch, Essex) has been adapted for a ligand differentiation immunoassay. The method is based on competitive binding of the analyte, e.g., oestriol 16α-glucuronide (I), and labelled antigen, e.g., [3H]I, to the specific antibody, enzymatic transformation of the free ligand into a more hydrophobic derivative and separation of the antibody-bound and free ligand by partition into organic and aqueous phases. Detection is with a liquid scintillation counter with a flow cell and a flat-bed recorder. The method was rapid, each sample of, e.g., urine taking 55 min to process, and 30 results h-1 could be obtained. Down to 6.68 nM I could be determined in urine.
16-α-Glucuronideoestriol Clinical analysis Immunoassay Scintillation counter

"Separation And Characterization Of Dermatan Sulfate In Normal Human Urine"
Biol. Pharm. Bull. 1993 Volume 16, Issue 4 Pages 340-342
Guoning QIU, Masahiko TANIKAWA, Hiroshi AKIYAMA, Toshihiko TOIDA, Ichiro KOSHIISHI, Toshio IMANARI

Abstract: Dermatan sulfate excreted in normal human urine was isolated and characterized by TLC and cellulose acetate strip electrophoresis after cetylpyridinium chloride precipitation and pronase digestion. In these separation methods, dermatan sulfate and chondroitin sulfate were extracted and then monitored by sensitive HPLC methods with post-column fluorometric derivatization coupled with chondroitinase ABC, ACII and B digestion. From the results, we demonstrated that human urinary dermatan sulfate contains iduronic acid as its major uronic acid (80-90% of total uronic acid), and is composed mainly of repeated mono-sulfated disaccharide units and small numbers of di-sulfated disaccharide units (Di-diSB, 7% and Di-diSE, 1%).
Sulfate HPLC Fluorescence Post-column derivatization

"Multi-functional Flow Injection Biosensor For The Simultaneous Measurement Of Creatinine, Glucose And Urea"
Biosci. Biotechnol. Biochem. 1993 Volume 57, Issue 2 Pages 191-194
Rui, C.S.;Ogawa, H.I.;Sonomoto, K.;Kato, Y.

Abstract: A manifold is described (diagram given) incorporating enzyme reactors containing urease, creatinine deiminase, glutamate dehydrogenase, glutamate oxidase and glucose oxidase, delay coils and an O electrode. The flow stream was split into three channels, those passing through the urease and creatinine deiminase reactors were merged before passing through the glutamate dehydrogenase and glutamate oxidase reactors. All streams were merged before passing to the O electrode. The working solution was 67 mM Na - K phosphate buffer solution (pH 8.0) containing 0.1 mM EDTA, 0.3 mM NADH and 5 mM 2-oxoglutarate. Calibration graphs were rectilinear from 0.2 to 5 mM creatinine, 0.2 to 10 mM glucose and from 0.5 to 20 mM urea. The removal of endogenous interfering substances such as NH3 may allow the analysis of urine with this system.
Creatine Glucose Urea Sensor Multidetection Interferences

"Improvement Of The Selectivity Of An Flow Injection Analysis Amperometric Biosensor System For Glucose"
Biosens. Bioelectron. 1993 Volume 8, Issue 5 Pages 239-247
K. B. Male and J. H. T. Luong*

Abstract: In the cited flow injection analysis system, samples (75 µL) were injected into a stream (31 ml/h) of 1 mM acetate buffer of pH 4-7.2 and carried to a column (12 cm x 2.54 mm i.d.) of acetate AG 1-X8 anion-exchange resin (200-400 mesh) to remove interfering substances including uric acid and ascorbic acid. The stream then merged with a stream (31 ml/h) of 100 mM acetate buffer of pH 5.5 containing 1 M NaCl and passed through an enzyme reactor column (6 cm x 2.54 mm i.d.) prepared by immobilizing glucose oxidase onto aminopropyl glass beads using glutaraldehyde (details given) and packing the beads into Tygon tubing. H2O2 was determined using an amperometric flow cell with an Immunodyne membrane (3 µm) and a Pt electrode held at +700 mV vs. Ag/AgCl. The optimum pH for ascorbic acid and uric acid removal were 4 and >6, respectively; the anion-exchange column was less efficient at removing paracetamol. The calibration graph was linear for up to 1 mM glucose and the detection limit was 10 µM. Reproducibility was good and the enzyme reactor was stable for >2000 analyzes; sample throughput was 17/h. The method was applied to urine, plasma, fruit juices and pea and bean seed extracts (details given). A flow injection analysis (flow injection analysis) biosensor system has been developed for the determination of glucose from urine, blood plasma and foodstuffs. Glucose oxidase was immobilized onto porous aminopropyl glass beads via glutaraldehyde activation to form an enzyme column. The hydrogen peroxide released from the conversion of glucose to gluconic acid was monitored by a platinum electrode vs. silver/silver chloride poised at +700 mV. As a novel aspect to the improvement of the selectivity of the biosensor system, an anion exchange column was placed upstream to remove uric acid, ascorbic acid or acetaminophen, three major electroactive interfering substances which usually occur in urine and blood plasma. Among several resins tested, the effective adsorption of uric and ascorbic acids could be accomplished using an acetate anion exchanger, and the selectivity coefficient was pH dependent. The binding of acetaminophen to the resin was much less efficient and, in all cases, the selectivity coefficient was independent of the operating temperature up to 37°C. When applied to real samples, the data obtained by the biosensor system compared well with those of the standard hexokinase assay. The immobilized glucose oxidase could be reused for at least 2000 repeated analyzes without loss of its original activity.
Glucose Amperometry HPIC Electrode Sensor Biotechnology Selectivity Immobilized enzyme Interferences Glass beads

"Amperometric Flow Injection Analysis Of Creatinine Based On Immobilized Creatinine Deiminase, Leucine Dehydrogenase And L-amino-acid Oxidase"
Biosens. Bioelectron. 1994 Volume 9, Issue 6 Pages 429-437
Chang-Sheng Rui and Yasuhiko Kato*, Kenji Sonomoto

Abstract: Two flow injection manifolds are described. In the first, glutamate dehydrogenase was used to remove endogenous NH3, then the mixture passed through three reactors containing creatinine deiminase (to produce NH3 from creatinine), leucine dehydrogenase (to convert NH3 to L-leucine) and L-amino-acid oxidase, respectively; L-leucine oxidation was monitored using an O2 electrode. In the alternative system, a two-channel approach was used in which endogenous NH3 and L-amino acids were simultaneously compensated for with a two-channel system based on the principle of split and confluence of flow (details given). The methods were applied to determine creatinine in urine. For the single-channel system, the response time was ~1 min, the calibration graph was linear for up to 5 mM creatinine and the detection limit was 0.2 mM; the results correlated well with those obtained by the Jaffe method. With the two-channel system (less expensive to operate) the sensitivity was improved and the results correlated well with those obtained by the Jaffe method.
Creatinine Amperometry Immobilized enzyme

"Non Segmented Continuous-flow System With Polarographic Detection For The Determination Of Ranitidine In Pharmaceutical Formulations And Urine"
Bol. Soc. Chilena Quim. 1998 Volume 43, Issue 1 Pages 45-53
Jaque Olmedo, P.;Toral, M.I.;Richter, P.

Abstract: In this work we developed a method by flow injection analysis for the determination of ranitidine in pharmaceutical forms and urine, using a polarog. flow through cell as detection system which has been designed recently in our lab. The method is based on the reduction of the group nitro of the drug to the hdyroxylamine derivative by applying a potential of -1.40 V vs. mercury pool electrode. It was found a determination range of 2.38 x 10^-5 M ranitidine, with a detection limit of 7.15 x 10^-6M. The relative standard deviation (n = 11) for a concentration. level of 1.0 x 10^-6 M was 2.1%, which is comparable with the obtained by the manual methodology The accuracy of the method was evaluated by comparison of the results with those obtained by DC polarog. and UV spectrophotometry and the results were quite comparable.
Ranitidine Electrode Polarography Method comparison

"Amperometric Determination Of Glucose, Galactose, Free Cholesterol, And Choline In Serums By Flow Injection Analysis With Immobilized Enzyme Reactors"
Bunseki Kagaku 1983 Volume 32, Issue 4 Pages 253-258
Toshio YAO, Yoshiaki KOBAYASHI

Abstract: Glucose oxidase, galactose oxidase, cholesterol oxidase, and choline oxidase were immobilized and were used for determination of respective substrate in a continuous flow system. These enzymes were immobilized by reaction with glutaraldehyde onto the surface of alkylamino-bonded silica gel and packed in glass tubes (5 mm x 4 mm i.d.) as the enzyme reactors in the flow system. By positioning an electrolytic column just before the point of the immobilized enzyme reactors, the electroactive species such as L-ascorbic acid and uric acid in human serum could be eliminated. The hydrogen peroxide produced enzymatically in the enzyme reactors could be monitored amperometrically by an electrochemical flow cell. Calibration curves were linear for glucose in the range (5700) mg dl-1, for galactose in the range (104000) mg dl-1, for free cholesterol in the range (5200) mg dl-1, and for choline in the range (8200) mg dl-1. Sample sizes were 5 µL for glucose and galactose assays, and 2 µL for free cholesterol and choline assays. But linear ranges could be changed by varying the sample sizes. The assays could be performed at a 120 samples h-1 rate with satisfactory precision (<2% RSD) at a flow rate of 4.8 ml min -1. The immobilized enzyme preparations retained most of their original activities after repetitive use for more than three months, except for the immobilized galactose oxidase.
Glucose Galactose Cholesterol Choline Amperometry Reactor Immobilized enzyme

"Determination Of Antihypertensive Agent, (2R,4R)-2-(2-hydroxyphenyl)-3-(3-mercaptopropionyl)thiazolidine-4-carboxylic Acid By High Performance Liquid Chromatography With Post-column Derivatization With N-(9-acridinyl)maleimide"
Bunseki Kagaku 1984 Volume 33, Issue 6 Pages E207-E210
Suzuki, T.;Akasaka, K.;Meguro, H.

Abstract: The cited drug(I) in 20 mM EDTA was determined by HPLC on a column (13.5 cm x 4.6 mm) of Nucleosil 5SA with a pre-column of the same material and 50 mM phosphate buffer (pH 5.0) as mobile phase (1 mL min-1). The pH of the eluate was adjusted to 7.9 by mixing with 0.2 M KOH (0.4 mL min-1), and N-(9-acridinyl)maleimide solution in acetonitrile (1 mg l-1) was added at ~0.5 mL min-1. The mixture was passed through a reaction coil (10 m x 0.25 mm), and the fluorescence was measured at 435 nm (excitation at 360 nm). The calibration graph was rectilinear for 0.01 to 1 nmol of I. For determination of I in urine, the sample was first electrolytically reduced by a modified Weitzman apparatus (cf. Anal. Biochem., 1976, 76, 170) to convert any of the disulfide form of I into the thiol form.
(2R-4R)-2-(2-Hydroxyphenyl)-3-(3-mercaptopropionyl)thiazolidine 4-carboxylic acid HPLC Fluorescence Post-column derivatization

"Flow Injection Analysis With Membrane Separation. Determination Of Ammonia In Blood And Urine"
Bunseki Kagaku 1984 Volume 33, Issue 10 Pages 505-509
Aoki, T.;Uemura, S.;Munemori, M.

Abstract: The sample, made alkaline with 1 M NaOH, was injected into the outer tube of a separation unit (shown diagrammatically), which comprised an inner micro-porous PTFE tube containing phthalaldehyde - 2-mercaptoethanol reagent, and an outer tube containing water. Ammonia permeated into the inner tube and the reaction product flowed into a flow cell for fluorimetric determination at 486 nm (370-nm excitation). Calibration graphs were rectilinear for 1 µM to ~1 mM NH3. Various compounds commonly found in blood and urine did not interfere. Recovery of NH3 was 95 to 108, 104 to 110 and 97 to 101% from whole blood, plasma and urine, respectively.
Ammonia Clinical analysis Fluorescence Gas diffusion Interferences Teflon membrane

"HPLC Of Reducing Sugars With Post-column Fluorescence Derivatization Using Methoxybenzamidine"
Bunseki Kagaku 1989 Volume 38, Issue 11 Pages 568-572
Kai, M.;Tamura, K.;Watanabe, H.;Ohkura, Y.

Abstract: L-Rhamnose, L-fucose, D-fructose and D-glucose were separated by HPLC on a column (15 cm x 4 mm) of LiChrosorb SI-60 (5 µm) with a mobile phase (1 mL min-1) of acetonitrile - 10 mM tetraethylenepentamine (TEPA)- 50 mM taurine (17:1:2). The eluate was mixed with 40 mM 4-methoxybenzamidine (MBA) and 1.0 M KOH and heated at 100°C for ~19 s in a reaction coil (5 m x 0.4 mm). After passing through a cooling coil (1 m x 0.4 mm) at 25°C, the fluorescence was measured at 470 nm (310-nm excitation). The post-column fluorescence reaction with MBA was slightly inhibited with TEPA. Detection limits ranged from 2.3 to 20 pmol for a 100 µL injection. The method was applied in analysis of serum and urine. The system could also be used with other HPLC elution systems, e.g., aqueous acetonitrile or 0.05 to 0.5 M borate buffer of pH 7 to 11.
Sugars, reducing Fluorescence Post-column derivatization

"Determination Of Oxalate By Flow Injection Analysis (FIA) With Electrogenerated Chemiluminescence Detection"
Bunseki Kagaku 1990 Volume 39, Issue 6 Pages 323-326
Uchikura, K.

Abstract: Sample (10 µL) was injected into the carrier stream of water (0.3 mL min-1) and mixed with reagent solution (0.8 mL min-1) of 10 mM H2SO4 containing 0.12 mM tris(bipyridyl)ruthenium dichloride (I). The oxidation potential of the working electrode in the home-made electrochemical reactor, in which tris(bipyridyl)ruthenium3+ was continuously generated from I, was maintained with a potentio-galvanostat. Calibration graphs were rectilinear up to 16 pmol of oxalate. The detection limit was 0.3 pmol and the coefficient of variation was 2.3% (n = 5). The method was applied to the determination of oxalate in urine. Relative chemiluminescence intensities are tabulated for >30 compounds; tryptophan interferes.
Oxalate Chemiluminescence Calibration Detection limit Interferences

"FIA Of Urine Oxalate By The Titanium(IV) - 4-(2'-pyridylazo)resorcinol Reagent"
Bunseki Kagaku 1991 Volume 40, Issue 7 Pages 343-347
Matsubara, C.;Sakai, K.;Takamura, K.

Abstract: Urine (5 µL) was injected into a carrier (0.3 mL min-1) and passed through a column of immobilized oxalate oxidase. The produced H2O2 was determined by measuring the absorbance of the complex formed with the cited reagent at 508 nm. The calibration graph was rectilinear from 2 µM to 1 mM oxalate; coefficient of variation (n = 10) at 40 µM was 1.0%. The throughput rate was 40 samples h-1. Metallic ions did not interfere.
Oxalate Column Immobilized enzyme Interferences

"Selective Determination Of Triphosphonucleotide By A Flow Injection - Chemiluminescence Method"
Bunseki Kagaku 1993 Volume 42, Issue 3 Pages 183-190
Ohno, Y.;Hobo, T.;Tamura, R.;Ishii, M.

Abstract: Triphosphonucleotide, e.g., ATP, was chemically loaded on to Cu(II)-modified zeolite. The system comprises three flow lines, one of which contains the exchange column (15 cm x 4.5 mm) of Cu - zeolite (0.074 to 0.125 mm) with chemiluminescent detection of eluted Cu(II). The detection limits were 50 fmol to 20 pmol of ATP, 60 fmol to 1.0 pmol of uridine triphosphate, 50 fmol to 3 pmol of guanosine triphosphate and 80 fmol to 1 pmol of cytidine triphosphate; the coefficient of variation (n = 5) was 2.1% for 1 nM-ATP. There was no interference from other nucleotides or their derivatives at 0.1 mM in the determination of 1 nM ATP. The method was applied to the determination of the number of bacteria in normal human urine.
Chemiluminescence Immobilized reagent Interferences

"Development Of Fluorimetric Determination With Photoirradiation In Hydrogen Peroxide Solution"
Bunseki Kagaku 1995 Volume 44, Issue 2 Pages 165-166
Matawari, K.

Abstract: The fluoriphore generated by kynurenic acid (I) upon photoirradiation in H2O2-containing solution was tentatively identified by 13C NMR as 3,4-epidioxy-3,4-dihydro-4-hydroxyquinoline-2(1H)-carboxylic acid. HPLC with detection based on this reaction has been used to determine I in only 0.1 mL of serum, with deproteinization with HClO4. A corresponding FIA technique has been used to determine I in urine, a bypass line in the manifold permitting simultaneous measurement of the background fluorescence.
Kynurenic acid HPLC Fluorescence Post-column derivatization Photochemistry

"Investigation And Application Of LC/1H-NMR Using Semimicro LC And A Micro-probe"
Bunseki Kagaku 1998 Volume 47, Issue 11 Pages 845-851
Tadao Fukuhara, Kazuo Komatsu, Seiichi Yoshida, Okihiko Sakamoto, Shinya Yamamoto and Tasuku Takamatsu

Abstract: A semimicro LC/1H-NMR was constructed with a 3 mm i.d. micro-probe equipping a glass NMR flow cell of ~50 µL volume A semimicro polymer-coated ODS column (1.5 mm i.d. x 250 mm) was used for various studies with a mobile phase of D2O, and deuterated an acetonitrile mixture at a 100 µL/min flow rate. Identification and detection limits were determined by a flow injection mode for Et p-hydroxybenzoate as ~5 µg and sub µg, respectively. A comparison of a UV chromatogram and a protonogram, which was obtained by projecting the on-flow spectrum on the time-axis was made in order to study the state of diffusion of the sample in the NMR flow cell. The results indicated that a separation of adjacent peaks eluted through LC was well maintained in the NMR flow cell. The semimicro system was also applied to a keto-enol tautomeric mixture, which was hardly isolated by a preparative procedure. Each tautomer was identified by the individual spectra of the keto and enol forms, and the usefulness of semimicro LC/1H-NMR has been fully demonstrated.
4-hydroxyethylbenzoate Nuclear magnetic resonance Method comparison

"A Sensitive Post-column Derivatization/UV Detection System For HPLC Determination Of Antitumour Divalent And Quadrivalent Platinum Complexes"
Chem. Pharm. Bull. 1995 Volume 43, Issue 1 Pages 108-114
Kizu, R.;Yamamoto, T.;Yokoyama, T.;Tanaka, M.;Miyazaki, M.

Abstract: Methods for the determination of cisplatin (I), oxoplatin (II), carboplatin (III), oxaliplatin (IV) and tetraplatin (IV), in human plasma ultrafiltrate and urine (100 l samples) are described). For I, an MCI gel CDR10 column (8 cm x 4.6 mm i.d.) was used with 10 mM acetate buffer of pH 5.5 containing 0.1 M Na2SO4 and 30% acetonitrile as mobile phase. For II a MCI gel CPK08 column of similar dimensions was used with 50 mM K2SO4 as mobile phase. For III, IV and V and Inertsil ODS-2 column (25 cm x 4.6 mm i.d.) was used with 10 mM acetate buffer of pH 5.5 containing 5% acetonitrile as mobile phase. The flow rate was 1 ml/min and the columns were operated at 40°C. Post-column reaction at 60°C and 0.3 ml/min was performed with 40 mM NaHSO3 in 10 mM acetate buffer of pH 5.5 in a reaction coil (10 m x 0.5 mm i.d.) for detection at 290 nm. The calibration graphs were linear for 0.05-20 M-I, 0.1-20 M II, and 0.2-20 M III, -IV and -V and the corresponding detection limits were 20, 40, 60, 100 and 60 nM; the intra-day RSD were <5%. The recoveries were >>95%. The method was used to study the pharmacokinetics of I and II in rabbits.
Cis-platin Carboplatin Oxaliplatin Tetraplatin Oxoplatin HPLC Spectrophotometry Post-column derivatization

"Development And Performance Of An Automated HPLC Analyser For Catecholamines"
Chromatographia 1987 Volume 24, Issue 5 Pages 363-370
K. -S. Boos, B. Wilmers, R. Sauerbrey, E. Schlimme

Abstract: An automated dual-column HPLC system is described for the determination of catecholamines in body fluids, based on the use of a bonded-phase material with both size-exclusion and affinity-chromatographic properties (cf. Boos et al., '8. Koenigsteiner Chromatographie Tage', Waters GmbH, Koenigstein, 1985, p. 219), a microprocessor-controlled column-switching technique and an optional reaction system for post-column derivatization for fluorimetric detection. For a standard mixture of noradrenaline(I) and adrenaline(II), the detection limits were 300 and 2 pg of I or II with measurement of natural and trihydroxyindole fluorescence, respectively. From 20 fmol mL-1 to 3 nmol mL-1 of I and II can be determined. Coefficients of variation are tabulated for catecholamines in urine and plasma or serum.
Catecholamines Noradrenaline Adrenaline SEC LC Fluorescence Post-column derivatization

"Catecholamines:"
Chromatographia 1988 Volume 25, Issue 3 Pages 199-204
Boos, K.S.;Wilmers, B.;Sauerbrey, R.;Schlimme, E.

Abstract: Noradrenaline(I) and adrenaline(II) were determined in plasma (serum) and urine by using a pre-column (3 cm x 4 mm) of hydrophilic vinyl polymer and an analytical column (12.5 cm x 4 mm) of LiChrospher RP-18 (5 µm) linked by an automatic switching valve. The mobile phase was phosphate buffer of pH 8.7 for the pre-column and phosphate buffer of pH 3.0 - methanol - water in the analytical column. Post-column derivatization was effected by sequential treatment of the eluate with buffered K3Fe(CN)6, ascorbic acid and NaOH. The fluorescent trihydroxyindole derivatives formed were detected at 520 nm (excitation at 410 nm). The limit of detection was 2 pg. In urine, the within-batch coefficient of variation were 5.66 and 6.67% for I and II, respectively. Recoveries (n = 20) from urine were 93.61 ± 4.14 and 95.61 ± 3.25% for I and II, respectively; the corresponding figures for plasma (n = 15) were 103.54 ± 3.89 and 103.18 ± 4.11%.
Adrenaline Noradrenaline HPLC Fluorescence Post-column derivatization

"Establishment And Analytical Quality Control Of Laboratories For Hg Determination In Biological And Geological Samples In The Amazon, Brazil"
Cienc. Cult. 1998 Volume 50, Issue 4 Pages 255-260
WANDERLEY R. BASTOS, OLAF MALM, WOLFGANG C. PFEIFFER, DAVID CLEARY2

Abstract: During the past 20 yr significant amounts of Hg were released in the Amazonian environment due to gold mining activities. Several Brazilian and foreign research groups were studying the region, always facing difficulties regarding preservation and transfer of the collected samples from the field to the anal. labs. Aiming to solve these problems two high quality Hg anal. labs. were established in the region. One is located at Fundacao Esperanca (FE, Santarem, PA), a medical assistance foundation and the other at the Universidade Federal de Rondonia (UNIR), Porto Velho, RO. Their main equipment is: Atomic absorption spectrophotometers for Hg anal. (Flow Injection Mercury System-FIAS 400 with automatic samples-AS90-Perkin Elmer) and a microwave oven digestion system (MDS-2000-CEM). Technicians and researchers were trained in several aspects like environmental and human sampling, digestion methods and Hg anal. for biotic and abiotic materials. This training as well as the installation of the mentioned labs. were the responsibility of the Universidade Federal do Rio de Janeiro (UFRJ). Intercalibration exercises were performed between several labs.: Environmental Medicine of Odense University (Denmark), Center de Toxicologie du Quebec, Canada and Occupational Health Sciences (Health-Canada). In the last 18 mo the FE lab. joined the Hg urine anal. intercalibration program of the Lab. of the Center of Toxicol. in Quebec, Canada, reaching accurate results. To date both Amazonian labs. are able to analyze several different materials: Sediment, soil, fish, urine, hair and blood. The FE lab. is becoming more specialized in human samples such as urine, blood and hair, while UNIR lab. deals with environmental samples such as fish, sediment and soil.
Mercury Spectrophotometry Sample preparation FIAS-400 FIMS

"Urinary 4-hydroxy-3-methoxymandelic Acid As Measured By Liquid Chromatography, With One-line Post-column Reaction"
Clin. Chem. 1979 Volume 25, Issue 7 Pages 1234-1238
JG Flood, M Granger and RB McComb

Abstract: We describe a method for measurement of 3-methoxy-4-hydroxymandelic acid (vanillylmandelic acid, VMA) in urine. After the pH of the urine is adjusted to 2.7 and the sample is filtered, exactly 15 µL is injected onto a C-18 reversed-phase column. VMA is eluted from the column with 10 mmol/L phosphate buffer, pH 2.7, containing 30 mL of acetonitrile per liter. The eluate stream is combined with alkaline periodate and then passed through a 60°C water bath. The VMA is completely oxidized to vanillin, which is detected and quantitiated by its absorbance at 360 nm. No deterioration of the column was noted after 167 such injections of urine samples. Long-term control data indicate a CV of 12 and 10% at VMA concentrations of 1.5 and 5.8 mg/L, respectively. Although results correlate well (r = 0.976) with those by the method of Pisano et al. [Clin. Chim. Acta 7, 285 (1962)], they average 10% lower. Of 20 compounds tested, only methyl dopa interfered with the procedure as described.
Vanillylmandelic acid Clinical analysis HPLC Post-column derivatization Interferences

"Continuous-flow Enzymic Determination Of Creatine In Urine"
Clin. Chem. 1981 Volume 27, Issue 11 Pages 1888-1891
M Yasuhara, S Fujita, I Furukawa, K Arisue, K Kohda and C Hayashi

Abstract: A new enzymatic method is described for the determination of creatine in urine by continuous-flow analysis. The measurement is accomplished by transforming creatine to formaldehyde in reactions catalyzed by creatinase (creatine amidinohydrolase) and sarcosine dehydrogenase. The formaldehyde is reacted with 4-amino-3-hydrazino-5-mercapto-1,2,4- triazole to form a purple product, which is measured colorimetrically. The method gives a linear standard curve for creatine concentrations up to 100 mg/L. Precision and analytical recovery are excellent, and results correlate well with those by the more-difficult Folin method, which currently is most often used for this analysis.
Creatine Clinical analysis Spectrophotometry Enzyme Optimization Technicon Air segmentation Interferences Method comparison

"Urinary Oxalate Determination By Use Of Immobilized Oxalate Oxidase In A Continuous-flow System"
Clin. Chem. 1983 Volume 29, Issue 1 Pages 16-20
N Potezny, R Bais, PD O'Loughlin, JB Edwards, AM Rofe and RA Conyers

Abstract: In this procedure, oxalate oxidase (EC 1.2.3.4) immobilized in a continuous-flow system is used to determine oxalate in urine. The hydrogen peroxide formed from oxalate is detected by use of a color reaction with peroxidase (EC 1.11.1.7), 3-methyl-2-benzothiazoline hydrazine, and N,N-dimethylalanine. However, urine contains an oxalate oxidase inhibitor, which cannot be removed by heating, ion-exchange resins, or cellulose columns. This makes it necessary to precipitate the oxalate before assay. The overall assay system is accurate (oxalate recovery, 95.9%), sensitive (less than or equal to 5 µmol/L), precise (within-batch CV less than 1.25%, between-batch CV less than 5%), and relatively rapid (60 samples per working day). The assay system has better accuracy than an established chemical method and a gas- chromatographic method, and is considerably less arduous than and correlates well (r = 0.94) with a modified chemical method. The reference interval for urinary oxalate excretion is 0.16-0.56 mmol per day (n = 97). Only nonphysiological concentrations of ascorbate interfere with the assay, by increasing the oxalate result in the overall assay, presumably by post-micturition formation of oxalate from ascorbate in the urine samples.
Oxalate Clinical analysis Immobilized enzyme

"Continuous-flow System For Automation Of Latex Immunoassay By Particle Counting"
Clin. Chem. 1983 Volume 29, Issue 6 Pages 1007-1011
AM Bernard and RR Lauwerys

Abstract: The method is based on the agglutination, by protein, of calibrated latex particles coated with a specific antibody. The automated system consists of a modified sampler, a peristaltic pump, a thermostatic bath, a manifold, an optical cell counter equipped with a double-threshold system, and a recorder with a continuously adjustable scale. The reaction mixture (sample plus antibody-coated latex beads) is incubated in a heated mixing coil for 25 min, and the extent of agglutination is measured with the cell counter. No external shaking is required. A wide variety of proteins in plasma and urine, including human ferritin, β2-microglobulin, retinol-binding protein and albumin, have been determined. The detection limits range from 1 pM to 0.1 nM. Within- and between-assay coefficient of variation are <10%. In the assay of ferritin, sera are pre-treated to prevent interference from chylomicrons, complement and rheumatoid factor.
Proteins Ferritins β-2-Microglobulin Albumin, protein Clinical analysis Biochemical analysis Immunoassay Interferences Heated reaction Latex

"Urinary Glycollate Measured By Use Of L-2-hydroxyacid Oxidase"
Clin. Chem. 1985 Volume 31, Issue 5 Pages 710-713
R Bais, JM Nairn, N Potezny, AM Rofe, RA Conyers and A Bar

Abstract: Glycollate is determined by the action of L-2-hydroxyacid oxidase. The H2O2 produced is detected in the presence of peroxidase by use of an indicator reaction with 3-methyl-2-benzothiazoline hydrazine and NN-dimethylaniline. Urine samples are treated with activated charcoal before analysis to reduce interferences of reducing substances. Correction must be made for lactate in urine, which interferes. An accurate, precise and sensitive continuous-flow system, with use of enzyme immobilized on the inner surface of nylon tubing is described, but this is unsuitable for routine use because of the instability of the enzyme. A semi-automated procedure is described for the Cobas-Bio centrifugal analyzer. with use of enzyme in solution. Recovery by this method was 96% and within- and between-batch coefficient of variation were <2 and <5%, respectively. The normal reference interval for urinary excretion of glycollate is 0.13 to 1.31 mmol day-1.
Glycolate Glycollate Clinical analysis Interferences Immobilized enzyme Charcoal

"More-sensitive Enzyme-multiplied Immunoassay Technique For Procainamide And N-acetylprocainamide In Plasma, Serum And Urine"
Clin. Chem. 1988 Volume 34, Issue 5 Pages 957-960
PR Henry and RA Dhruv

Abstract: Procainamide(I) and N-acetylprocainamide(II) were determined by a commercial EMIT method (Syva Co.), modified to permit automated analysis of ~100 samples per day in a working range of 0.1 to 2.0 µg mL-1. A Gilford 203S continuous-flow system was used, with a Beckman Model DU spectrophotometer. The calibration graph was prepared by using I or II concentration. of 0, 0.1, 0.2, 1.6, 1.0 and 2.0 µg mL-1 and had a standard deviation of 5%. In a study in which 0.1 to 10 µg mL-1 of I and II were determined in duplicate, average recoveries, calculated from data obtained on two separate days were 99.5% (coefficient of variation 2.2%) and 100.4% (coefficient of variation 3.0%) for I and II, respectively. At extreme ratios of I to II the accuracy of determining the lower concentration. component became unsatisfactory.
Procainamide N-Acetylprocainamide Clinical analysis Spectrophotometry Immunoassay Simultaneous analysis

"Nonimmunological Assay Of Urinary Albumin Based On Laser-induced Fluorescence"
Clin. Chem. 1992 Volume 38, Issue 10 Pages 2089-2092
MA Kessler, MR Hubmann, BA Dremel and OS Wolfbeis

Abstract: We describe the first nonimmunological assay of albumin in urine with a detection limit of 1 mg/L. The method is simple, rapid, and accurate. It is based on the probe Albumin Blue 670, which becomes highly fluorescent on binding to albumin. An inexpensive diode laser was used as the light source for measurement of laser-induced fluorescence. The assay was coupled to a flow injection analysis system capable of running 20 samples per hour. The working range was 1-100 mg/L, which covered albumin concentrations found in nonpathological urine and in urine with slightly increased albumin. This range makes prediction of nephropathy possible at an early stage. Other serum proteins and hemoglobin do not interfere. The coefficients of variation were < 4% and < 7% within one day and from day to day, respectively. A correlation coefficient of 0.990 (n = 100) was obtained for comparison with the Behring nephelometric assay.
Albumin Fluorescence Clinical analysis Laser diode Interferences Method comparison

"Homocysteine And Other Thiols Determined In Plasma By HPLC And Thiol-specific Post-column Derivatization"
Clin. Chem. 1993 Volume 39, Issue 8 Pages 1590-1597
Anders Andersson, Anders Isaksson, Lars Brattstrom and Bjorn Hultberg

Abstract: For determination of total sulfhydryls, plasma or urine was incubated with dithiothreitol (I) for 15 min at 37°C, mixed with sulfosalicylic acid and centrifuged. For determination of free sulfhydryls, acid-pptd. plasma supernatant solution was mixed with boric acid, NaOH solution and I and incubated at 37°C for 15 min. Analysis was by HPLC on a column (10 cm x 3.2 mm) of Brownlee Velosep RP-18 (3 µm) with a mobile phase (0.8 ml/min) of 16 mM NaH2PO4/19 mM H3PO4/8 mM octyl sulfate/4.3% methanol (pH 2.4). Post-column derivatization was with 10 mM 4,4'-dithiodipyridine in 0.01 M HCl/methanol (97:3) and 300 mL of 0.3 M Tris/1 mM EDTA (pH 8.5) followed by detection at 324 nm. The limit of detection was 50 nM-homocysteine and the calibration graph was linear for 0.2-100 µm-homocysteine. The intra- and inter-assay RSD for plasma were 1.1-5.5% (n = 7) and 2.5% (n = 22), respectively. Recoveries were 94.0, 97.1, 86.5 and 112.3% for cysteine, homocysteine, glutathione and cysteinylglycine, respectively.
Cysteinylglycine Glutathione Cysteine Homocysteine HPLC Clinical analysis Post-column derivatization

"Determination Of Inorganic Arsenic And Its Organic Metabolites In Urine By Flow Injection Hydride Generation Atomic Absorption Spectrometry"
Clin. Chem. 1993 Volume 39, Issue 8 Pages 1662-1667
CP Hanna, JF Tyson and S McIntosh

Abstract: Urine was applied to a 1 mL Bond-Elut cartridge with HNO3/ethanol (1:10). The eluate was heated to ~120°C with solid K2Cr2O7 and concentrated HNO3 until the volume was reduced to ~1 mL and then concentrated H2SO4 was added. After heating to ~250°C for 90 min, the mixture was cooled for 1 min before H2O2 was added and the mixture reheated. After cooling, the mixture was treated with KI in HCl before flow injection AAS with mixing with HCl and sodium borohydride in NaOH solution Recovery was 108, 112, 104 and 95% for As(III), As(V), monomethylarsenic and dimethylarsenic, respectively. The detection limits were 0.1-0.2 µg/l and the RSD were 2.3-3.5%. A method has been developed for the determination of inorganic arsenic [As(III) and As(V)] and its organic metabolites (monomethylarsenic and dimethylarsenic) in urine by flow injection hydride generation atomic absorption spectrometry. The nontoxic seafood-derived arsenobetaine and arsenocholine species were first separated by a solid-phase extraction procedure. The remaining sample was digested with a mixture of nitric and sulfuric acids and potassium dichromate, followed by attack with hydrogen peroxide. The resulting As(V) was reduced to As(III) with potassium iodide in hydrochloric acid before injection into the flow injection manifold. The percentage analytical recoveries (mean±95% confidence interval) of various arsenic species added to a urine specimen at 250 µg/L were 108±2, 112±11, 104±7, and 95±5 for As(III), As(V), monomethylarsenic, and dimethylarsenic, respectively. For the determination of arsenic in Standard Reference Material 2670 (toxic metals in human urine), results agreed with the certified value (480±100 µg/L). Analyses of samples for the Centre de Toxicologie du Quebec, containing seafood-derived species, demonstrated the viability of the separation procedure. Detection limits were between 0.1 and 0.2µg/L in the solution injected into the manifold, and precision at 10 µg/L was between 2% and 3% (CV). These preliminary results show that the method might be applicable to determinations of arsenic in a range of clinical urine specimens.
Arsenic, inorganic Arsenic(3+) Arsenic(5+) Monomethylarsine Dimethylarsenic Spectrophotometry Clinical analysis Volatile generation Reference material Speciation Volatile generation

"HPLC Analysis Of Oligosaccharides In Urine From Oligosaccharidosis Patients"
Clin. Chem. 1994 Volume 40, Issue 6 Pages 914-921
Gi.jsbert 0. H. Peelen, Jan G. N. de Jong, and Ron A. Wevers

Abstract: The HPLC method previously reported (Anal. Biochem., 1991, 198, 334) using a Dionex CarboPac PA1 column has been evaluated for comparison with the normal TLC screening procedure for ten different lysosomal diseases. Patterns from six types of oligosaccharidoses were compared with normal urinary patterns and with the TLC patterns. As the use of pulsed amperometric detection appeared to be non-specific it was applied only to desalted samples. Post-column derivatization was more specific and was applied to non-desalted samples although lower resolution was obtained. The peaks obtained were identified on the basis of the retention times of commercially available oligosaccharides or by removal of the relevant bands from the TLC plate. It was considered that HPLC with its higher resolution and possibility of quantification, can more generally be used for the recognition of abnormal oligosaccharides, and for the detection of increased excretion or content of known oligosaccharides in urine, cells, or other body fluids.
Oligosaccharides HPLC Clinical analysis

"Direct Stopped-flow Fluorescence Polarization Immunoassay Of Abused Drugs And Their Metabolites In Urine"
Clin. Chem. 1994 Volume 40, Issue 8 Pages 1489-1493
Dolores Perez-Bendito, Augustina Gomez-Hens and Abaji Gaikwad

Abstract: Two solution were prepared for filling the two drive syringes of the stopped-flow module. One contained 10 µL of urine and an appropriate volume of the fluorescein-labelled analyte in buffer in a final volume of 0.5 mL. The other contained an appropriate volume of the antibody in 0.5 mL of buffer. Portions (40 µL) of the two solution were transferred to the mixing chamber at 20 ml/s. The time course of the fluorescence intensity was measured in the two emission channels at 550 nm (excitation at 494 nm). The stopped-flow module was computer-controlled and the initial reaction rate was determined in 5-10 s. The procedure was exemplified by the determination of amphetamine and of the metabolites benzoylecgonine and 11-nor-Δ8-tetrahydrocannabinol-9-carboxylic acid. Calibration graphs for these three were 20-300, 15-300 and 10^-400 µg/l respectively, with detection limits of 7, 5 and 3 µL/l, 3-12 times lower than by conventional fluorescence polarization immunoassay. The new method was also more precise (RSD of 1.4-3.6%, vs. 2.2-7.4%) and recovery was close to 100%. The correlation between the two methods was excellent (r > 0.99).
Drugs Amphetamine Benzoylecgonine Immunoassay Fluorescence Clinical analysis Stopped-flow Computer Method comparison

"Spectrophotometric Determination Of Urinary Iodine By Flow Injection Analysis With Online Catalytic Digestion"
Clin. Chem. 1996 Volume 42, Issue 12 Pages 2021-2027
ZHANG YAPING, YUAN DONGXING, CHEN JIXIANG, LAN TIANsHIu, and CHEN HUIQIN

Abstract: A portion (40 µL) of urine/HCl (100:1) was injected into a stream of 0.513 M NaCl in 0.9 M H2SO4 which passed through a PTFE reaction coil (1 m x 0.7 mm i.d.), merged with a 1.8 M H2SO4 stream containing 12.7 mM KMnO4 and 3.4 mM K2Cr2O7, passed through a similar 1.9 m reaction coil (RC), merged with a stream of 0.125 M As2O3 (details given), passed through a 1.4 m RC, merged with a 0.513 M NaCl stream containing 29.6 mM MnSO4, passed through a 1.4 m RC, merged with a 8 mM cerium(IV) stream (details given), passed through a 1.5 m RC, merged with a 3.8 mM brucine stream and passed through a 0.9 m RC prior to detection at 480 nm. The flow rates were 1.5 ml/min (except 0.9 ml/min for cerium sulfate and brucine solutions) and the coil temperatures were 38°C (except last coil at room temperature). A calibration graph was obtained from 39 nM- (detection limit) to 7.88 µM-iodine, recoveries were 92-104% and within-run RSD (n = 6) were The sampling rate was 70/h. Sample stability and the effects of sample dilution and interferences were also studied (results given). A flow injection technique involving online catalytic digestion and spectrophotometric detection has been developed for the determination of iodine in urine. After urine samples are digested by KMnO4-K2Cr2O7- H2SO4 solution, the iodine in the urine catalyzes the reaction of As(III) with Ce(IV). The remaining Ce(IV) is then reacted with brucine and the product is detected with a spectrophotometer at 480 nm. With this technique, we obtained a detection limit for urinary iodine of 0.039 µmol/L, and the linear range was 0.039-7.88 µmol/L with a CV < 3%. Analytical recovery ranged between 92% and 104% (mean 99%). The sampling frequency of the flow injection technique was 70/h. We applied the method to measure the iodine concentration in a freeze-dried urine reference sample and in collected urine samples, and compared the results with those obtained by the accepted alkaline ashing technique. The proposed technique has the advantages of being simple, rapid, precise, accurate, and sensitive. It can be used to assess iodine- deficient populations as well as those receiving treatment.
Iodine Sample preparation Spectrophotometry Clinical analysis Catalysis Reference material Method comparison Interferences Online digestion

"Determination Of Oxalate In Urine By Flow Injection Analysis"
Clin. Chim. Acta 1986 Volume 156, Issue 1 Pages 71-75
Enrico Gaetani, Carlo F. Laureri, Marina Vitto, Loris Borghi, Gian Franco Elia and Almerico Novarini

Abstract: A method is described for the determination of oxalate in urine using flow injection analysis and fluorimetry. Oxalate is precipitated with calcium chloride at pH 4.5, redissolved in H2SO4 and measured by flow injection analysis. The minimum detection limit is 6 µmol/l. The coefficient of variation is 7%. Results are in good accordance with normal values found with traditional oxalate analysis. Oxalate was isolated from acidified (5 M HCl) urine samples by precipitation with 66 mM CaCl2.4H2O at pH 4.5, and the ppt. was dissolved in 4.5 M H2SO4. Portions (10 µL) of the diluted solution were injected into a carrier stream (15 mL h-1) of 0.35 M H2SO4, which was mixed with a solution of zirconyl chloride (3 µM) - flavonol (14.7 µM) pumped at 100 mL h-1. The fluorescence quenching produced by the oxalate was measured at 480 nm (excitation at 350 nm). The calibration graph (peak area vs. oxalate concentration.) was rectilinear from 10 to 360 µM with a detection limit of 6 µM. Recovery was 95% with a coefficient of variation of 7%. Results agreed well with those obtained by conventional methods.
Oxalate Clinical analysis Fluorescence Method comparison Quenching

"Automated Colorimetric Assay For Urine Nicotine Metabolites: A Suitable Alternative To Cotinine Assays For The Assessment Of Smoking Status"
Clin. Chim. Acta 1987 Volume 170, Issue 2-3 Pages 255-262
Eino V. J. Puhakainen*, Robert D. Barlow and Jukka T. Salonen

Abstract: A modification of the direct barbituric acid colorimetric method previously described (Barlow et al., Ibid., 1987, 165, 45) for determination of urinary nicotine is described. The method has been automated with use of a continuous-flow autoanalyzer. (described and illustrated). Response was rectilinear up to 250 µM (cotinine equivalents). The coefficient of variation was 6.8% (n = 10). Up to 250 samples per day could be analyzed. Results correlated well (r = 0.91) with those by RIA.
Nicotine Clinical analysis Spectrophotometry Method comparison

"Coupling Continuous Sample Treatment Systems To Capillary Electrophoresis"
Crit. Rev. Anal. Chem. 1998 Volume 28, Issue 1 Pages 63-81
Miguel V&aacute;lcarcel, Angel R&iacute;os, Lourdes Arce

Abstract: The state of the art and prospects for the combined use of continuous sample treatment systems and custom-made and commercially available capillary electrophoresis equipment is presented and discussed. Sample treatment in this separation technique is of great practical relevance by virtue of its inherent shortcomings, which include low sensitivity, small sample volumes, and a marked influence of matrix components. The main technical types of coupling (in-line, on-line, and mixed) are dealt with systematically and compared to manually implemented approaches in order to derive practical conclusions with a view to developing new technical applications and facilitate use by routine laboratories.
Proteins Electrophoresis Interface Automation

"Online Chemiluminescence Assay Using FIA And Fiber Optics For Urinary And Blood Glucose"
Enzyme Microb. Technol. 1993 Volume 15, Issue 5 Pages 424-428
M. V. Cattaneo and J. H. T. Luong

Abstract: A chemiluminescence fiber optic system coupled to flow injection analysis (FIA) and ion exchange chromatography has been developed for determining glucose in blood and urine. Immobilized glucose oxidase acted on β-D-glucose to produce hydrogen peroxide, which was then reacted with luminol in the presence of ferricyanide to produce a light signal. Endogenous ascorbic acid and uric acid present in urine or blood samples were effectively retained by an upstream acetate anion exchanger. In addition, acetaminophen could also be adsorbed by this ion exchanger. The detection system exhibited a sensitivity of 1.315±0.044 RU µM-1 for glucose with a minimum detection level of 1 µM. When applied for the determination of urinary and blood glucose levels, the results obtained compared well with those of the reference hexokinase assay. Immobilized glucose oxidase was reused for over 500 analyzes without losing its original activity. A conservative estimate for the reuse of the acetate ion exchange column was about 100 analyzes.
Glucose Chemiluminescence Biotechnology HPIC Matrix removal Method comparison Optical fiber

"Determination Of Creatinine In Urine By Flow Injection Analysis"
Fenxi Ceshi Tongbao 1992 Volume 11, Issue 1 Pages 55-58
Li Guodong;Peng Banying Tian Liqing;Zhi Zhenglian

Abstract: The air segmented flow injection analysis system is adapted to analyze creatine in urine samples without predilution in nonequilibrium condition. Ninety samples can be analyzed within 1 h with a relative standard deviation of 1.5%.
Creatinine

"Application Of Flow Injection Analysis To Clinical Chemistry. Determination Of Creatinine In Serum"
Fenxi Huaxue 1988 Volume 16, Issue 12 Pages 1116-1118
Xia, B.;Liu, S.

Abstract: A flow injection system is described, in which creatinine(I) is determined with use of picric acid as chromogenic reagent; the absorbance is measured at 505 nm. The calibration graph is rectilinear from 1 to 20 mg L-1 of I in serum or urine. The coefficient of variation (n = 10) is 1.8%. Sixty samples can be analyzed in 1 h.
Creatinine Clinical analysis Spectrophotometry Calibration Chromogenic reagent

"Determination Of Trace Platinum By Flow Injection Analysis - Adsorptive Stripping Voltammetry And Catalytic Polarographic Hydrogen Wave"
Fenxi Huaxue 1990 Volume 18, Issue 1 Pages 20-24
Wei Guizhen Lu Zongpeng* Alan M.Bond

Abstract: Platinum solution (0.1 µg mL-1; 100 µL) is injected into the flow injection analyzer. and reacts in a stream (0.27 mL min-1) of 0.002% hydrazine sulfate - 0.36 M H2SO4 and 0.04% formaldehyde - 0.36 M H2SO4. Detection is by adsorptive stripping voltammetry at -0.3 V for 60 s and measurement of the catalytic hydrogen wave at -0.8 V. Recoveries were 93.7 to 100% with a coefficient of variation of 5%. The calibration graph was rectilinear for 10 pg to 1 ng of Pt. Twenty samples can be run per hour. The method was applied in the analysis of urine, fish meal, milk powder, ox liver, minerals and organoplatinum compounds.
Platinum Voltammetry Polarography Catalysis Calibration

"Spectrophotometric Determination Of Ascorbic Acid In Vitamin C Tablets, Beverages, Orange And Urine With 2,6-dichloroindophenol By Flow Injection Analysis"
Fenxi Huaxue 1991 Volume 19, Issue 2 Pages 182-184
Ma, H.C.;Feng, J.Z.;Cao, B.

Abstract: Sample is injected into a carrier stream of potassium hydrogen phthalate buffer of pH 3.6 (2 mL min-1) for reaction with a reagent stream of 0.2 mM dichloroindophenol (1.5 mL min-1) in a 15-cm reaction coil before kinetic spectrophotometric detection at 525 nm. For the analysis of vitamin C tablets, oranges, beverages and urine by use of the standard-additions method, recovery was 72 to 117%. For 50 µg mL-1 of I, the coefficient of variation was 0.5%. Detection limit was 0.5 µg mL-1. The calibration graph was rectilinear up to 50 µg mL-1. Interference was observed from Fe(III); most co-existing ions (e.g., Zn and Cu), sugars, amino-acids and organic acids (such as citric acid) did not interfere.
Ascorbic acid Spectrophotometry Buffer Interferences Kinetic Standard additions calibration

"Simultaneous Determination Of Doxycycline And Vitamin B2 By Flow Injection Fluorimetry"
Fenxi Huaxue 1992 Volume 20, Issue 11 Pages 1261-1264
Zhao, Y.B.;Yu, Z.X.;Guo, X.Q.;Xu, J.G.;Chen, G.Z.

Abstract: Urine (120 µL) was injected into a carrier stream (4 mL min-1) of water (pH 6 to 7), which merged with a water stream (4 mL min-1) before passing through a 12-cm reaction tube. The stream was irradiated with a Hg lamp and fluorescence due to riboflavine (I) was measured at 520 nm. The stream then merged with a reagent stream (4 mL min-1) containing 0.1 M MgSO4, which forms a fluorescent complex with doxycycline (II). Total fluoresence due to I and II was measured at 520 nm. Contributions to total fluorescence, and hence concentration, were calculated for I and II; the calibration graphs were rectilinear from 80 nM to 20 µm and 3 to 80 µM, respectively, with corresponding detection limits of 60 nM and 2 µM. Recoveries of I and II were 95 to 102%.
Doxycycline Vitamin B2 Fluorescence Simultaneous analysis UV reactor Complexation Photochemistry

"Flow Injection Analysis For L-lactate In Human Fluid With Immobilized Dehydrogenase Reactor"
Fenxi Huaxue 1992 Volume 20, Issue 12 Pages 1373-1377
Tang, Q.;Hu, G.J.;Li, Q.F.;Du, H.H.

Abstract: L-Lactate dehydrogenase (I) was immobilized by amination of porous silica gel with [3-(2-aminoethyl)-propyl]triethoxysilane using glutaraldehyde as coupling reagent. The support immobilized I was packed in a column and used in a flow injection system (diagram given). The system was washed with 0.1 M phosphate buffer solution, followed by carrier stream (pH 9.8) containing 40 mM phosphate, 2 mM NAD+, 6.7 mM EDTA, 0.5 M NaCl and NaN3 before ultrafiltered sample (serum or urine) was injected. Detection was at 340 nm. The calibration graph was rectilinear from 0.1 to 4.4 mM L-lactic acid with a detection limit of 0.4 nM. Recoveries ranged from 96 to 103% and the coefficient of variation was 1.2%.
l-Lactate Spectrophotometry Immobilized enzyme Silica gel Column

"Speciation Analysis Of Mercury By Liquid Chromatography Coupled With Online Sorbent Extraction Preconcentration And Cold Vapor Atomic Absorption Spectrometry"
Fenxi Huaxue 1996 Volume 24, Issue 11 Pages 1248-1252
Yin, X.F.;Liu, M.

Abstract: A mixture of methyl-, ethyl- and phenylmercury (I, II and III, respectively) and Hg(II) was injected into a flow injection HPLC - cold vapor AAS integrated manifold (diagram given) for pre-concentration for 9 min then speciation. A 5 µm Zorbax ODS column (25 cm x 4.6 mm i.d.) was used with methanol/acetonitrile/H2O (50:22:28) containing 3 mM dithiocarbamate as mobile phase (1 ml/min). Online reduction with 1% NaBH4 in the presence of 75% HNO3 was carried out with combined thermolysis and detection at 254 nm. All components were well separated. Calibration graphs were linear. Detection limits for I, II, III and Hg(II) were 0.86, 1.94, 1.06 and 1.92 ng/l, respectively. Recoveries were 92-106% with RSD of 3.8-7%. Most foreign species were either removed during pre-concentration or did not interfere. The method was applied to the analysis of urine.
Mercury LC Spectrophotometry Sample preparation Interferences Preconcentration Speciation Solid phase extraction

"The Direct Determination Of Cadmium In Urine By Flow Injection Online Ion-exchange Preconcentration Flame Atomic Absorption Spectrometry"
Fenxi Shiyanshi 1993 Volume 12, Issue 6 Pages 55-57
Dong Liping and Fang Zhaolun

Abstract: Urine (3.5 ml) was acidified with 35 µL of concentrated HNO3 and adjusted to pH 3 with aqueous NH3 or dilute HNO3. The sample solution (3.5 ml) was merged online with 0.5 M ammonium acetate buffer solution (pH 9, 0.3 ml/min) and applied to a conical column packed with CPG-8HQ ion-exchanger; Cd was eluted with 2 M HCl (5 ml/min) directly into the nebulizer of a flame AAS instrument for determination of Cd at 228.8 nm. An enrichment factor of 30 was obtained at a sampling frequency of 60/h. The detection limit was 0.3 ng/ml. The RSD (n = 11) for 40 ng/ml of Cd was 1.5%. Results for a reference standard sample agreed well with reported values.
Cadmium Spectrophotometry Preconcentration

"Enzyme-catalyzed Determination Of 2-oxoisocaproate By Flow Injection Analysis And Its Application To The Monitoring For Maple Syrup Urine Disease"
GBF Monogr. Ser. 1991 Volume 14, Issue 1 Pages 145-148
Tauschensky, S., Hummel, W., Schadewaldt, P., Wendel, U.

Abstract: A simple and fast method for the determination of 2-axoisocaproate in plasma samples by use of NAD Dependent D-2-hydroxyisocaproate dehydrogenase (Hic-DH) from Lactobacillus casei ssp. is described. The enzyme is immobilized on aminopropyl-CPG and applicated in a flow-injection system with detection of NADH absorbance. Applicability is demonstrated by comparative measurement of 2-oxoisocaproate levels in plasma samples of patients with maple syrup urine disease by the photometric method and the flow-injection analysis.
2-Oxoisocaproate Catalysis Enzyme

"Determination Of Trace Mercury In Environmental And Biological Samples By Flow Injection Hydride-generation Graphite-furnace AAS"
Guangpuxue Yu Guangpu Fenxi 1993 Volume 13, Issue 5 Pages 107-110
Ma, Y.P.;Gulikezi;Fang, X.H.

Abstract: Pre-treated sample (500 µL) was injected and carried by a stream of water (6 ml/min) to react with streams of 5 M HCl and 0.3% KBH4 (both at 1 ml/min). After passing through a gas-liquid separator, the generated Hg was carried by Ar at 50-80 ml/min to a self-made Au-coated graphite-furnace for AAS, with pre-concentration and atomization temperature of 45-160°C and 500°C and 600°C, respectively. By standard-additions method, recovery was 98-101%; RSD were 5-10%. The calibration graph was linear with a detection limit of 20 pg of Hg. The method was applied to assay of human hair, urine, soil and peach leaf. No interference was observed from co-existing ions. Sampling rate was 50 runs per h.
Mercury Spectrophotometry Interferences Preconcentration Standard additions calibration

"Determination Of Trace Cobalt, Nickel And Cadmium By Online Flow Injection Analysis With Coprecipitation Preconcentration Flame AAS"
Guangpuxue Yu Guangpu Fenxi 1994 Volume 14, Issue 1 Pages 85-90
Dong, L.P.;Fang, Z.L.

Abstract: Ox liver (0.2 g) or urine (10 ml) was placed in a PTFE crucible, treated with 3 mL of HNO3/HClO4 (10:1) and the mixture was heated at 170°C to near dryness. The residue was treated with ~15 mL of hot water, the solution was mixed with 100 µL of 1% Fe(III) and 1 drop of 1% thiosalicylic acid. The solution was adjusted to pH 3 with saturated sodium acetate solution, mixed dropwise with 2% ascorbic acid until the red color disappeared, treated with 3 drops of the reagent in excess and water to 10 mL. The solution was fed at 2 ml/min into a FIA system (diagram given). Co, Ni and Cd were co-precipitated with ammonium pyrrolidinedithiocarbamate-Fe complex, the precipitate was dissolved with methyl isobutyl ketone and the solution was introduced into a Perkin-Elmer atomic absorption spectrophotometer. The detection limits of Co, Ni and Cd were 1, 3 and 3 ng/ml, respectively. The RSD were 2.3% for 20 ng/ml of Co, 2% for 100 ng/ml of Ni and 2.4% for 10 ng/ml of Cd. Results agreed with the certified values.
Cobalt Nickel Cadmium Spectrophotometry Reference material Preconcentration Coprecipitation MIBK

"Multiplexed Four-channel Online Iodine Monitor"
Instrum. Sci. Technol. 1994 Volume 22, Issue 3 Pages 217-229
J. E. Atwater; R. R. Wheeler Jr.; R. L. Sauer; J. R. Schultz

Abstract: A PC controls four three-way PTFE solenoid valves (via an ACCESS IOD-24 buffered 24 bit digital I/O card that controls eight relays on an ACCESS ROB-8 board) to multiplex up to four sample streams into the flow cell of a diode-array spectrophotometer interfaced to the PC through an IEEE-488 parallel bus. The remaining four relays of the ROB-8 board multiplex K-type thermocouples in each of the streams to a digital thermometer that is connected to the PC through an RS 232 serial link. Iodine in drinking water for use on spacecraft, and also in, e.g., humidity condensate, urine distillate and reclaimed hygiene water, is determined at 464 nm after subtraction of the background absorbance at 600 nm. The response is linear for up to 10, 25 and 300 mg/l of I2 in all these matrices (calibration with aqueous standards prepared from refrigerated ethanol containing 1 g/l of I2) in flow cells of pathlengths 10, 5 and 1 cm, respectively. Separate failures of the deuterium lamp and its power supply and the necessity for replacement of two relays and three valves were the only causes of downtime during otherwise continuous operation for 18 months.
Iodine Spectrophotometry

"SIRE-technology. 1. Amperometric Biosensor Based On Flow Injection Of The Recognition Element And Differential Measurements"
Instrum. Sci. Technol. 1998 Volume 26, Issue 1 Pages 45-57
D. Kriz; C. Berggren; A. Johansson; R. J. Ansell

Abstract: An amperometric biosensor with injection of the recognition element (SIRE) is described. An oxidase enzyme is injected into the measuring chamber, separated from the sample by a semi-permeable membrane. It is possible to make measurements in the presence and absence of enzyme and subtract the background current. This differential measuring technique has been difficult with previous sensors because it is very difficult to match two sensors. The versatility of the biosensor was demonstrated by determination of several different metabolites (glucose, lactate, Ph alanine, and galactose). The system was not optimized for the individual analytes, but showed a linear response for each up to approximately 10 mM. For glucose, a detection limit of approximately 2 µM was achieved. By using the differential measuring technique, glucose could be determined by direct measurement in a urine sample with the standard addition method. The repeatability was found to be lower than 3.7 % (n=5) over the range 0.3-5.0 mM for glucose, and the reproducibility better than 5 % (n=5). The biosensor showed no decrease in response at temps. up to 60°C and could easily be cleaned with a solution of hydrogen peroxide and by sweeping of the potential. Thus, this amperometric biosensor was found to have several advantages compared to conventional ones.
Glucose Lactate Phenylalanine Galactose Amperometry Sensor Membrane Standard additions calibration Differential detection Apparatus

"Continuous-flow Quantification Of Total Mercury In Whole Blood, Plasma, Erythrocytes And Urine By Inductively Coupled Plasma Atomic-emission Spectroscopy"
J. Anal. Toxicol. 1992 Volume 16, Issue 2 Pages 99-101
Buneaux F, Buisine A, Bourdon S, Bourdon R.

Abstract: For the determination of Hg, blood and urine underwent sample preparation (details given), before dilution with aqueous NH3 buffer and reduction by sodium borohydride at pH 9.5. The reduced mixture was analyzed by ICP-AES; the test material sample was not nebulized into the torch, but the Hg vapor was collected in a reactor vial and swept into the plasma by the carrier gas (Ar) using a glass apparatus (described). An oxidative mineralization was not required. Optimization of the experimental conditions is discussed. The separation of liquid and gaseous phases decreased background noise and increased the sensitivity of the method; the detection limit was 4 µg l-1. The coefficient of variation (n = 9) was 9% for 35 µg L-1 of Hg. Recoveries were quantitative. The method can be used for routine determinations but it is recommended that a specific standardization is first performed. Mercury determination in blood and urine can be performed by inductively coupled plasma atomic emission spectroscopy after dilution in an ammonia buffer and reduction by sodium borohydride. The proposed method does not need an oxidative mineralization. The sample is not nebulized into the torch, but the mercury vapor, after collection in a reactor vial, is swept into the plasma by the argon carrier gas using the described glass app.
Mercury Spectrophotometry Optimization Volatile generation Phase separator Volatile generation

"Inorganic, Organic, And Total Mercury In Blood And Urine: Cold Vapor Analysis With Automated Flow Injection Sample Delivery"
J. Anal. Toxicol. 1996 Volume 20, Issue 1 Pages 17-22
David E. Nixon, Garry V. Mussmann, and Thomas P. Moyer

Abstract: For inorganic Hg digestion, 6.5 mL water containing 12.5% concentrated HNO3 and 12.5% concentrated H2SO4 was combined with 2 mL 5% KMnO4 and 0.5 mL blood or 1 mL urine was added. The mixture was vortexed every 15 min for 60 min at room temperature and then centrifuged at 3000 rpm for 10 min. The volume was adjusted to 9 mL with water. For total Hg digestion, 0.2 g K2S2O8 was mixed with 4 mL concentrated HNO3 and 0.5 mL H2SO4 and 0.5 mL blood or 1 mL urine was added. The mixture was heated at 95°C for ~30 min. The samples were analyzed by flow injection cold vapor AAS (Perkin-Elmer Corp.) with measurement at 253.7 nm and liquid flow rates of 1.14 ml/min for 5% SnCl2 and 1.4 ml/min for 3% HCl (sample probe wash solution) and the sample. Ar was used as carrier gas (60 mL/min). Calibration graphs were linear from 0.5-25 µg/L. RSD were 7-20%. The method was applied to the determination of inorganic, organic and total Hg in blood and urine samples from a normal human population.
Mercury Spectrophotometry Sample preparation Speciation

"Determination Of Specific Proteins By The FIA Principle"
J. Autom. Methods Manag. Chem. 1990 Volume 12, Issue 2 Pages 53-59
IB ANDERSEN

Abstract: Transferrin, haptoglobin, IgG, IgA, IgM and orosomucoid in plasma, and albumin in urine were determined by flow injection analysis on a FIA Star (Tecator) system. Samples were diluted up to 200-fold with carrier solution and a 40 µL portion was injected into carrier solution of 0.05 M phosphate - 0.1 M NaCl buffer (pH 7.4) containing 4 or 7% of polyethylene glycol and mixed with antibody solution; detection was at 405 nm. The results are presented for each protein; the method is not suitable for IgG, IgA and IgM and can be used for orosomucoid if a kinetic setup is applied.
Transferrin Haptoglobin Immunoglobulin G Immunoglobulin A Immunoglobulin M Orosomucoid Albumin Tecator Kinetic

"Evaluation Of The Jokoo-ION 150AC: Guidelines For The Evaluation Of Analysers By Ion-selective Electrodes"
J. Autom. Methods Manag. Chem. 1990 Volume 12, Issue 3 Pages 116-128
JOAN FARR&Eacute;, CARMEN BIOSCA, and ROM&Aacute;N GALIMANY

Abstract: Details are given of the cited automated analyzer. for Na, K and Cl- which incorporates ion-selective electrodes and is applied to blood, serum or diluted urine. The unit has a Ag - AgCl (saturated KCl) reference electrode, a glass membrane electrode for Na, a liquid membrane electrode based on valinomycin with PVC as support for K, and, for Cl-, a liquid membrane electrode based on ion exchange involving quaternary ammonium salts in a polymeric solvent. The unit was evaluated by comparison with a SMAC II (Technicon) continuous-flow analyzer. and an IL 943 flame photometer (Instrumentation Laboratory), and gave acceptable performance in terms of detection limits, linearity, drift and carry-over. The electrode slope, electrode response, sample temperature and pH effects, effects of high concentration. of proteins or lipids, and influence of haematocrit on the Na, K and Cl- concentration. were also evaluated. The strategy is generally applicable to ion-selective electrode analyzer.s.
Sodium Potassium Chloride Electrode Electrode Electrode Electrode Electrode Detection limit pH Detector Apparatus

"Mechanistic Studies Of Ion-selective Electrodes"
J. Biomed. Eng. 1985 Volume 7, Issue 3 Pages 183-195
Moody GJ

Abstract: A knowledge of the chemical composition of blood, urine and other body fluids is a daily requirement for departments of biochemistry. Electronic circuitry and computers to process the data are readily available, but satisfactory transducers to convert chemical composition into electrical signals are frequently the weakest link in the chain of measurement. This review is concerned with one group of transducers: ion-selective electrodes. Since the commercial success of the calcium and fluoride ions-selective electrodes in the mid-sixties, a range of other electrodes has become available. Their use has already conferred considerable benefits upon medicine, e.g. rapid, low-cost, multiple assay of major blood components; diagnostic surveys of chloride sweat levels relating to cystic fibrosis; and monitoring blood fluorides during and after halothane administration. Their adoption for indirectly sensing enzymes and associated substrates is particularly noteworthy. Recent advances in electronics, coupled with flow injection schemes based on ion-selective electrodes, have facilitated the management of hundreds of samples daily. However, developments in the mechanistic knowledge of these sensors have not matched the increase in their application, although definite progress can be reported; for example with regard to the origin of the potential signals induced by ion activities in solution. Numerous techniques have been devised to unravel mechanistic problems, among which radioisotope tracer and impedance measurements may be cited as especially valuable. Selectivity performance, particularly in complex biological media, and undesirable features such as protein poisoning, need further research. Organic chemists are now better placed to synthesize new designs of acyclic and cyclic molecules as mobile site, ion-selective, sensor materials which, with appropriate mediator solvents, provide improved sensor cocktails. This design feature is well illustrated by the continuing guest for a lithium ion-selective electrode compatible with the high levels of sodium interference in blood.
Fluoride Electrode Interferences Review

"Flow Injection Analysis: A New Approach To Laboratory Automation"
J. Clin. Lab. Autom. 1984 Volume 4, Issue 3 Pages 169-182
Seitz, W.R.;Grayeski, M.L.A.

Abstract: In this review the principle of flow injection analysis is described, and its advantages over segmented-flow analysis are summarized. Basic equipment configurations and operating techniques are outlined, and applications to the determination of chemical and enzymatic constituents of serum and urine are cited. (64 references).
Clinical analysis Review

"Flow Injection Analysis With Membrane Separation"
J. Flow Injection Anal. 1984 Volume 1, Issue 2 Pages 13-20
Makoto Munemori

Abstract: Various analysis using membranes (e.g. glucose and ammonia) are discussed.
Ammonia Carbon dioxide Glucose Chemiluminescence Spectrophotometry Membrane

"Determination Of Mercury In Urine And Whole Blood By Flow Injection Analysis-cold Vapor Atomic Absorption Spectrometry"
J. Flow Injection Anal. 1992 Volume 9, Issue 1 Pages 13-19
M. BURGUERA, J.L. BURGUERA and M. GALLIGNANI

Abstract: A flow injection cold vapor atomic absorption spectrometric method for the determination of mercury in urine and whole blood was devised. The calibration graph is linear up to 25 µg/L with a detection limit of 0.1 µg/L (0.1 mg of mercury). The relative standard deviation varied between 1.4 and 1.7%. The values obtained by this method were in good agreement with the certified values. The mean urine and blood contents of 128 unexposed human subjects were 1.0 and 2.5 µg/L, respectively.
Mercury Spectrophotometry Reference material

"Flow Injection Spectrophotometric Determination Of Salicylate Using Online Solid-phase Extraction"
J. Flow Injection Anal. 1996 Volume 13, Issue 1 Pages 45-52
Karlicek, R.;Gargos, M.;Solich, P.

Abstract: Sample solution (200 µL) was injected into a carrier stream of water (0.55 ml/min) of a flow injection system (schematic shown) and carried to a SPE column (0.5 cm x 2 mm i.d.) packed with quaternary ammonium-modified silica gel. The adsorbed salicylate (I) was eluted from the column with 50 µL 0.05 M HNO3 and injected into the carrier solution. The analyte-containing carrier stream was mixed with a reagent stream of iron(III) nitrate solution in 20 mM HNO3 at 0.25 ml/min in a reaction coil (150 cm x 0.5 mm i.d.) before detection at 540 nm. The calibration graph was linear from 1-20 µg/ml of I. The RSD (n = 10) was 0.44% for 10 µg/ml of I. All interfering substances were removed by the SPE process. The method was applied to the analysis of urine and blood serum, with recoveries of 98-101.4 and 98-102%, respectively, for 10^-200 and 10^-50 µg/ml of added I. Sampling rate of 30-60 runs per h could be achieved. There was no need for pretreatment.
Salicylate Spectrophotometry Sample preparation Silica gel Column Solid phase extraction Interferences

"Latex Immunoassay Of Transferrin In Urine"
J. Immunol. Methods 1991 Volume 144, Issue 1 Pages 49-55
A. Bernard*, K. S. Chia and R. Lauwerys

Abstract: A fully automated assay based on latex particle agglutination is described. The assay is carried out in a continuous-flow system (as described by Bernard and Lauwerys (Clin. Chem., 1983, 29, 1007) which was modified to include a Tecan 505 manipulator which automatically dilutes urine samples and standards. Urine was incubated for 30 min at 50°C with latex particles adsorbed with anti-transferrin antibody (prep. described); residual unagglutinated particles were quantified with an optical particle counter. The assay ranged from 0.5 to 10 µg L-1 of transferrin. Intra- and inter-assay coefficient of variation were from 2.1 to 11.8% and the average recovery was 102.5%. The latex immunoassay of transferrin was adapted to give a turbidimetric reading; agglutination was quantified by measuring the decrease in absorbance at 360 nm (full details given).
Transferrin Immunoassay Spectrophotometry Turbidimetry Automation Dilution Heated reaction Latex

"New Fluorimetric Detection Method Of Corticosteroids After High Performance Liquid Chromatography Using Post-column Derivatization With Glycinamide"
J. Liq. Chromatogr. Relat. Technol. 1983 Volume 6, Issue 6 Pages 1131-1138
Tokuichiro Seki; Yoshihisa Yamaguchi

Abstract: Some biological corticosteroids were detected by a new fluorimetric method using post-column derivatization with glycinamide. Urinary corticosteroids which are hydrolyzed and extracted from sample fluid are detected by the reaction with glycinamide in the presence of hexacyanoferrate (III) in weakly alkaline media of borate buffer solution of pH 9.8 at 90°C for 5 min. This method is highly sensitive and specific for some corticosteroids and the reaction is performed under mild condition, compared with the fluorimetric method using the reaction with sulfuric acid, so that this method can be used for fractional assay of urinary corticosteroids of patients for a steroid abnormal metabolism.
Corticosteroids HPLC Fluorescence Post-column derivatization

"Ion-pair Liquid Chromatographic Analysis Of Phenylpropanolamine In Plasma And Urine By Post-column Derivatization With Phthalaldehyde"
J. Liq. Chromatogr. Relat. Technol. 1985 Volume 8, Issue 8 Pages 1489-1500
Robert J. Y. Shi; Winnie L. Gee; Roger L. Williams; Leslie Z. Benet; Emil T. Lin

Abstract: Plasma (0.5 ml) was extracted with 5 mL of CH2Cl2 containing α-methylbenzylamine(I) as internal standard and 0.5 M K2HPO4 solution at pH 11. After centrifuging the mixture, the organic layer was added to a 0.1% solution of HCl in acetonitrile. The solution was evaporated to dryness under N and the residue was dissolved in 200 µL of mobile phase prepared from 2400 mL of acetonitrile, 1600 mL of water, 0.8 g of Na heptane-1-sulfonate and 12 mL of anhydrous acetic acid. Aliquots (40 to 100 µL) were analyzed by HPLC on a column (15 cm x 4.6 mm) containing Ultrasphere ODS (5 µm) with mobile phase at 1.0 mL min-1 and post-column derivatization with phthalaldehyde (details given) and detection by fluorescence measurement at 418 nm (excitation at 340 nm). Urine samples (0.2 ml) were analyzed similarly but without extraction with CH2Cl2, and the mobile phase and column dimensions differed slightly. Calibration graphs based on peak height ratio were rectilinear for 2 to 200 ng mL-1 of phenylpropanolamine in plasma and for 0.5 to 150 µg mL-1 in urine. The detection limits in plasma and urine were 2 ng mL-1 and 0.5 µg mL-1, respectively. The within-day and day-to-day coefficient of variation were <10%.
Phenylpropanolamine HPLC Fluorescence Post-column derivatization

"Liquid Chromatographic Determination Of A Substituted Benzamide In Biological Fluids Using Preconcentration And Post-column Extraction"
J. Liq. Chromatogr. Relat. Technol. 1987 Volume 10, Issue 8-9 Pages 1903-1916
C. de Ruiter; U. A. Th. Brinkman; R. W. Frei

Abstract: Plasma or urine (diluted 1:1 and 1:9, respectively, with 10 mM phosphate buffer of pH 3.0), containing S-(-)-3-bromo-2,6-dimethoxy-N-(1-propylpyrrolidin-2-ylmethyl)benzamide as internal standard, was applied to a pre-column (2 cm x 4.6 mm) of Baker C8 or C18 material or to a disposable cartridge packed with C8 material. The analytical column (10 cm x 4.6 mm) was packed with Spherisorb ODS-2 (3 µm). All columns were pre-treated with hexadecyltrimethylammonium bromide. The mobile phase (1 mL min-1) was aqueous 10% acetonitrile adjusted to pH 3.0 with H3PO4. Post-column derivatization was carried out online with aqueous 0.1 mM Na 9,10-dimethoxyanthracene-2-sulfonate (pH 3.0) and derivatives were extracted into 1,2-dichloroethane. Detection was by fluorescence measurement at 452 nm (excitation at 383 nm). Detection limits were 1 and 15 ng mL-1 of remoxipride [S-(-)-3-bromo-N-(1-ethylpyrrolidin-2-ylmethyl)-2,6-dimethoxybenzamide;(I)] in plasma and urine, respectively. Recoveries were 88 ± 4 and 76 ± 4% of I from plasma and urine, respectively, and corresponding coefficient of variation were 3.5 and 2.2% (n = 5).
S-(-)-3-bromo-N-(1-ethylpyrrolidin-2-ylmethyl)-2,6-dimethoxybenzamide HPLC Fluorescence Sample preparation C8 C18 Preconcentration Post-column derivatization Post-column extraction

"Fluorescamine Post-column Derivatization For The HPLC Determination Of Cephalosporins In Plasma And Urine"
J. Liq. Chromatogr. Relat. Technol. 1988 Volume 11, Issue 14 Pages 2993-3010
M. D. Blanchin; H. Fabra; B. Mandrou

Abstract: Plasma or urine (10 µL) was applied to a column (25 cm x 4 mm) of LiChrosorb RP-18 (7 µm), fitted with a guard column (1 cm x 4 mm) of the same material, with 25 mM phosphate buffer of pH 7.0 - acetonitrile (19:1, 9:1 or 17:3) as mobile phase (1 mL min-1). Post-column derivatization was performed in a PTFE coil (4.5 m x 0.25 mm) with fluorescamine solution (0.2 mg mL-1) in acetonitrile at 0.25 mL min-1. Fluorimetric detection was at 485 nm (excitation at 385 nm). Calibration graphs were rectilinear from 10 to 500 ng of cefaclor, cephalexin, cephradine, cefroxadine, cephaloglycin and cefadroxil. Detection limits ranged from 0.3 to 1.8 ng, and coefficient of variation (n = 12) were 4%. Recoveries were generally 90%.
Cefaclor Cephalexin Cephradine Cefroxadin Cephaloglycin Cefadroxil HPLC Fluorescence Post-column derivatization

"Fluorimetry Of Tryptophan Metabolites (indole Compounds And Kynurenine Compounds)"
Biol. Pharm. Bull. 1984 Volume 7, Issue 1 Pages S10-S10
IINUMA FUMIO; MAWATARI KEN-ICHI; KOYANAGI MASAHIRO; TABARA MASAYOSHI; WATANABE MITSUO

Abstract: Tryptophan metabolites were determined fluorimetrically after oxidation with H2O2 - CuSO4. Procedure: To a 0.5 mL portion of the sample solution was added 2.5 mL of a solution 15 mM in H2O2, 12 mM in CuSO4 and 150 mM in Na2CO3 - NaOH (pH 12.2), and the mixture was incubated at 80°C for 20 min. Detection was by fluorimetry at 385 nm (with excitation at 315 nm). A HPLC method is described for quantitative separation of kynurenine and tryptophan in serum by using H2O2 - CuSO4 as post-column derivatization reagent. 3-Hydroxykynurenine in urine was determined following reaction with H2O2 and peroxidase; detection was by fluorimetry at 520 nm (with excitation at 350 nm).
Indoles Kynurenine HPLC Fluorescence Post-column derivatization

"Flow Injection Analysis Of Inorganic Cationic Species In Serum And Urine"
J. Trace Elem. Electrolytes Health Dis. 1989 Volume 3, Issue 2 Pages 97-101
Araujo AN, Lima JL

Abstract: Three flow injection analysis systems are presented for the determination of (i) Na, K and Li, (ii) Ca and Mg, and (iii) Cu, Zn and Fe in serum and for Na, K and Ca in urine. Detection is by flame photometry for Na and K and by AAS for the other cations. Sampling rates of ~80, 180 and 240 h-1 are achieved for (i), (ii) and (iii), respectively, and calibration graphs are rectilinear up to 200 mM Na, 175 mM K, 2 mM Li, 15 mM Ca, 2 mM Mg, 39 µM-Cu, 38 µM-Zn and 45 µM-Fe. The results are more precise than those obtained by flame photometry and AAS, with coefficient of variation of 0.5 to 1% in urine and 0.4 to 5.2% in serum. This paper describes three flow injection analysis (FIA) systems for the automatic determination of sodium, potassium, lithium, calcium, magnesium, zinc, copper and iron in certain biological fluids and compares the results obtained to those of flame photometry and atomic absorption spectrometry. The set-ups were designed to allow the samples to be prepared in the same manner as that used for batch procedures with the same analytical instrument. For determinations requiring a high sample dilution, it was found of definite advantage to split the stream and pass large amounts of liquid through the detection systems. The comparison of the results obtained by FIA and conventional methods yielded correlation coefficients in the range 0.990 to 0.999. The proposed methodology show good precision, with variation coefficients between 0.5% to 5%.
Sodium Potassium Lithium Calcium Magnesium Copper Iron Zinc Spectrophotometry Spectrophotometry Method comparison Sample splitting Dilution

"Automated Flow Injection Analysis Of Urinary Inorganic Sulfates"
Lab. Pract. 1980 Volume 29, Issue 12 Pages 1279-1280
Van Staden, J.F.;Basson, W.D.

Abstract: An automated, flow-injection turbidimetric method was used for the determination of inorganic sulfates in urine to increase sample output. The sample was injected automatically into the flow system from a flow-injection sampler containing a valve with a capacity of 200 µL, and 120 samples/h could be analyzed. The standard curve was linear in the range 4-15 mmol/L, and sample carryover was negligible. The relative standard deviation was 2.1%, and the recovery range 94.0-98.9%. The results correlated well with those obtained by the standard addition method. (SFS)
Sulfate Clinical analysis Spectrophotometry Turbidimetry Dialysis Method comparison

"HPLC System With Post-column Derivatization For Fully Automated Determination Of 4-hydroxy-3-methoxymandelic Acid In Urine"
Labor Med. 1989 Volume 12, Issue 9 Pages 410-412
Wilmers, B.;Boos, K.S.;Sauerbrey, R.

Abstract: In the system described urine (adjusted to pH 3.0) was applied to a pre-column of C18-modified polyol copolymer. 4-Hydroxy-3-methoxymandelic acid (I) was eluted with buffer solution of pH 8.5 on to the analytical column (25 cm x 4.6 mm) of LiChrospher RP-Select B (5 µm). The eluate was passed to a reaction coil for post-column reaction at 60°C (cf. Pisano et al. Anal. Abstr., 1962, 9, 4363). The vanillin produced was determined at 345 nm.
Acids HPLC Spectrophotometry Post-column derivatization Buffer Reactor Heated reaction

"Automatic Determination Of Mercury At The Lower Ng/l Levels"
LaborPraxis 1995 Volume 19, Issue 8 Pages 32-34
Baasner, J.

Abstract: An AS 90 or 91 sample dispenser and a flow injection AAS system (FIMS 100 or 400) with a high-intensity radiation source, a long-path cuvette and a wavelength-specific detector were used in the method. The working range is 20 ng-40 µg/l of Hg and the detection limit 5 ng/l. The method was used for the analysis of Hg in rain water, urine, blood, lemon leaves and sludges. Results agreed well with certified values. When the sample is pre-concentrated by amalgamation and blank values are determined and taken into account the working range and detection limits are 1-200 and 0.3 ng/l, respectively. With the use of amalgamation recoveries of 10 ng/l of Hg added to drinking water were 98-102%. The procedure is applicable to the hydride-generation AAS determination of other elements, e.g., As, Se or Sb.
Mercury Arsenic Selenium Antimony Spectrophotometry Spectrophotometry Amalgamation FIMS Reference material Volatile generation Volatile generation

"Determination Of The Toxicological-relevant Arsenic Content In Urine"
LaborPraxis 1998 Volume 22, Issue 11 Pages 18-22
Baasner, J.;Guo, T.Z.;Tsalev, D.L.

Abstract: A combination of the flow injection technique with the hydride AAS was applied to determine toxicol. relevant total As content in urine. L-Cys was used as preredn. agent. The detection limit was 1 µg/mL urine. A precision of 2% was found at a concentration. of 3 µg/mL.
Arsenic Spectrophotometry

"Coupling Of Microwave Digestion And Hydride AAS"
LaborPraxis 1993 Volume 17, Issue 4 Pages 44-48
Meyer, A.;Schwedt, G.

Abstract: An automated system is described for the interference-free determination of As and Se in protein-containing samples (serum and urine) without the need for sample separation. In the flow injection system, the sample is pumped with a digestion reagent through a coil in a microwave apparatus ('Maxidigest') and the product is injected into a stream of HCl carrier and reacted with sodium borohydride. After gas-liquid separation, the hydride gas is subjected to AAS. Optimization of the system is discussed.
Arsenic Selenium Sample preparation Spectrophotometry Microwave Automation Online digestion Interferences Phase separator Optimization

"Liquid Chromatography - Luminescence Methods"
Life Sci. 1987 Volume 41, Issue 7 Pages 901-904
Kazuko Mori

Abstract: Catecholamines in alumina extracts of urine or plasma or in tissue homogenates were separated by HPLC on TSK-gel ODS-1207 with KH2PO4 - acetonitrile - EDTA as mobile phase, pre- or post-column derivatization and fluorimetric detection. After post-column reaction based on trihydroxyindole formation with Fe(CN)63- as oxidant, the fluorescence of adrenaline and noradrenaline derivatives was measured at 520 nm (excitation at 410 nm). Dopamine could not, however, be detected in plasma by this method or by an alternative technique with electrochemical detection. The method could easily be automated, including a pre-column system. By pre-column derivatization with 1,2-diphenylethylenediamine (after cleanup on a cation-exchange column), dopamine and the other catecholamines could be determined in plasma; the detection limit was ~2 fmol. Fluorescence was measured at 480 nm (excitation at 350 nm).
Catecholamines Adrenaline Noradrenaline HPLC Fluorescence Sample preparation Post-column derivatization Pre-column derivatization

"Automated Continuous-flow Analysis Of Total Protein In Urine"
Med. Lab. Sci. 1984 Volume 41, Issue 1 Pages 66-67
O'Malley AH, Penney MD

Abstract: The manual micro-turbidimetric method of Iwata and Nishikaze (Anal. Abstr., 1980, 38, 3D197) has been automated; a flow diagram is illustrated and reagent solution compositions are given. Within-run coefficient of variation are typically 2 to 6% in the range 0.15 to 1.79 g L-1 of protein, the corresponding between-run values being 6 to 8%; carry-over is 1.6%.
Protein, total Turbidimetry

"Bioluminescence In The Continuous-flow Analysis Of Creatinine Using Immobilized Creatinine Amidohydrolase [creatininase]"
Med. Lab. Sci. 1985 Volume 42, Issue 4 Pages 310-317
Colliss JS, Wright JM, Ginman RF

Abstract: Serum was cleaned-up by addition of Dowex-50 cation-exchange resin and 6.5 mM HCl and the mixture was centrifuged after 30 min. Creatinine(I) was eluted from the resin with 0.125 M phosphate buffer (pH 12). The eluate was mixed with a solution containing ATP, Mg acetate and creatine kinase, and passed through a column of immobilized creatininase. The resulting solution was mixed with luciferin - luciferase and the bioluminescence was measured. Urine samples were diluted with water before analysis. Recoveries were 98 to 110 and 61 to 65% for I in urine and serum, respectively, and the coefficient of variation were 6.72%. Calibration graphs were rectilinear for 600 µM and 1 mM for urine and serum, respectively.
Creatinine Bioluminescence Ion exchange Resin Immobilized enzyme

"Direct Determination Of Urinary Oxalate By A Continuous-flow Method"
Med. Lab. Sci. 1990 Volume 47, Issue 2 Pages 73-79
Goldsack K, Ginman RF, Wright JM

Abstract: The sample, in water as carrier, is mixed with succinate buffer of pH 5.6 and passed through a reactor containing ascorbate oxidase (to oxidize ascorbate, which otherwise interferes) immobilized (method described) on the inner surface of O-alkylated nylon tubing. The stream is then mixed with succinate buffer of pH 2.0 before passage through a reactor containing immobilized oxalate oxidase, and 3,5-dichloro-2-hydroxybenzenesulfonic acid - peroxidase reagent is added to react with the H2O2 thus formed. The absorbance of the product is measured at 510 nm. Response is rectilinear for up to 0.5 mM oxalate. The method shows good selectivity. At 0.3 mM oxalate, the within- and between-batch coefficient of variation were 1.4 and 1.7%, respectively (n = 10). Recovery of added oxalate was >91%. Results were well correlated with those of an enzymatic 3-methylbenzothiazolin-2-one hydrazone method.
Oxalate Spectrophotometry Buffer pH Immobilized enzyme Selectivity Method comparison Interferences

"Flow Injection Analysis For Uric Acid By The Combined Use Of An Immobilized Uricase Reactor And A Peroxidase Electrode"
Nippon Kagaku Kaishi 1985 Volume 1985, Issue 2 Pages 189-192
Yao, T.;Sato, M.;Wasa, T.

Abstract: The sample (2 µL) is injected into a reactor containing immobilized urate oxidase. The carrier stream comprises 0.1 M borate buffer (pH 9.0) containing 0.2 M NaCl and 1 mM K4Fe(CN)6 and pumped at 1.5 mL min-1. The H2O2 generated in the reactor forms K3Fe(CN)6 in the presence of a peroxidase electrode. This electrode operates at only ~-50 mV vs. silver - Ag+, so that little interference is caused by other constituents of serum or urine. The peak current is rectilinearly related to uric acid concentration. in the range 0.2 to 8 mg dl-1. The peak width is ~30 s, so that 90 to 120 samples can be analyzed in 1 h with a coefficient of variation of 1 to 2%. Results show excellent agreement with those by the urate oxidase - u.v. method.
Uric acid Electrode Interferences Immobilized enzyme Method comparison Peak width

"Ion-exchange Separation And Fluorescence Measurement Of Isoenzyme Activity In Biological Samples"
Nippon Kagaku Kaishi 1986 Volume 1986, Issue 7 Pages 920-926
Takeda, T.;Yoshida, S.;Oda, K.;Hirose, S.

Abstract: A flow injection system with stream-switching is described for the continuous monitoring of the isoenzyme activity of lactate dehydrogenase in liquid chromatographic eluates. A µchromatographic column (2 cm x 1.5 mm) of DEAE-Sepharose and QAE-Sephadex was used with stepwise mobile phases of Tris-buffered 15, 30, 75, 100 and 150 mM NaCl. The isoenzyme fractions were treated with enzymatic reagents before fluorimetric measurement of NADH. The method could be applied to determination of isoenzyme activity fluorimetrically in urine.
Enzyme, lactate dehydrogenase SEC Fluorescence Post-column derivatization

"Quantification Of Imipenem's Primary Metabolite In Plasma By Post-column Chemical Rearrangement And UV Detection"
Pharm. Res. 1991 Volume 8, Issue 1 Pages 33-39
Donald G. Musson, Richard Hajdu, William F. Bayne and John D. Rogers

Abstract: Pre-treated samples (prep. described) were subjected to HPLC on a column (10 cm x 8 mm) of Resolve C18 Radial-PAK equipped with a column of RCSS Guard PAK C18 with a mobile phase of tetrabutylammonium hydrogen sulfate - H3PO4 - water, adjusted to pH 6.85 with 1 M KOH. The eluate was diluted with 0.426 M H3PO4 (0.6 mL min-1, passed through a column (25 cm x 4.6 mm) packed with 40 µm glass beads and the absorbance was measured at 295 and 320 nm. Calibration graphs were rectilinear for 1 to 100 µg mL-1 of the cited metabolite (I) in plasma and dialysate and for 5 to 100 µg mL-1 in urine . Coefficients of variation were 10%.
Imipenem, N-Formimidoyl thienamycin HPLC Spectrophotometry Column Glass beads pH Post-column derivatization

"Determination Of Emetine, Ergonovine, And Ergotamine By Periodate Oxidation In A Flow Injection System"
Pharmazie 1989 Volume 44, Issue 9 Pages 614-616
Martinez Calatayud, J.;Sagrado Vives, S.

Abstract: Emetine was determined in injection solution and urine (110 to 300 µL) by flow injection analysis, with injection of the solution into a periodate ion stream; this merged with a HCl stream (coil length 25 to 300 cm, flow rate 0.5 to 2.0 mL min-1) and the oxidized product was detected at 420 nm. The standard curve was rectilinear from 25 to 250 ppm; recoveries (urine) for emetine at 40 and 100 ppm were 88% and coefficient of variation were 1.5 and 2.7%, respectively. Ergometrine maleate and ergotamine tartrate were determined similarly.
Emetine Ergometrine Ergotamine Spectrophotometry Redox

"Determination Of 1,4-benzodiazepines By Flow Injection Analysis With Spectrophotometric Detection"
Quim. Anal. 1988 Volume 7, Issue 3 Pages 323-329
Prada, D.;Vicnete, J.;Lorenzo Abad, E.;Hernandez Blanco, M.;Hernandez, L.

Abstract: Optimum parameters for the determination of oxazepam, prazepam and clotiazepam comprise an injection volume of 250 µL, a reactor length and i.d. of 50 cm and 0.5 mm, respectively, a flow rate of 5 mL min-1 and a carrier stream of 0.1 M acetic acid - acetate buffer of pH 4.5. Detection is at 230 nm, and the sampling rate is 120 h-1. The method has been used to determine the drugs in formulations, by extraction with methanol and dilution of the extract with the carrier solution, and also in urine, by extraction at pH 7.0 (phosphate buffer) with ethyl ether.
Oxazepam Prazepam Clotiazepam Benzodiazepine, derivatives Drugs Clinical analysis Spectrophotometry Optimization

"A Flow Injection-hydride Generation-atomic Absorption Spectrometry Technique For The Online Determination Of Arsenic Species After Ion-exchange Separation And Of Total Arsenic After Microwave-assisted Digestion In Urine Samples"
Quim. Anal. 1997 Volume 16, Issue 3 Pages 165-176
Burguera, J.L.;Burguera, M.;Rivas, C.

Abstract: An online flow injection system comprising a separation column coupled to a hydride generation atomic absorption spectrometry system has been developed for the separation and sequential determination of inorganic (As(III) and As(V)) and organic (monomethylarsonic acid and dimethylarsinic acid) in 2 mL of urine samples. The separation of the arsenic species was performed with a combined cation-anion exchange column (Dowex 50W-X8 and AG 1-X8). While As(III) was not retained by the column, the following eluents: 0.006 mol L-1 trichloroacetic acid, 0.2 mol L-1 trichloroacetic acid and 5 mol L-1 NH4OH were used to eluate monomethylarsonic acid, As(V) and dimethylarsinic acid, respectively. After a cycle of the previous determinations was completed, total arsenic was sequentially determined in 0.1-2.0 mL samples after microwave assisted acidic mineralization/oxidation in a parallel and online module of the system. The continuous hydride generation for the determination of the different arsenic species was carried out by mixing downstream the acidified effluents (or digest for total arsenic) with a 15 % w/v KI + 5 % w/v ascorbic acid prereducing solution and thereafter with a 1.0% w/v sodium tetrahydroborate(III) solution The detection limits were 0.3, 0.3, 0.3, 0.5 and 0.2 ng of arsenic for As(III), As(V), monomethylarsonic acid, dimethylarsinic acid and total arsenic, respectively. The precision (relative standard deviation, RSD) of the method obtained in ten replicate anal. of urine spiked with arsenic species varied from 0.3 to 0.7%. Recovery values of the arsenic species were in the range 96-102 %. This method is applicable to the accurate determination of the arsenic metabolites and total arsenic in the urine of unexposed and exposed subjects.
Arsenic(3+) Arsenic(5+) Dimethylarsenic Monomethylarsine Arsenic, total Spectrophotometry Volatile generation Dowex Resin Column

"Determination Of Aflatoxins In Dust And Urine By Liquid Chromatography/electrospray Ionization Tandem Mass Spectrometry"
Rapid Commun. Mass Spectrom. 1995 Volume 9, Issue 13 Pages 1234-1237
Anders Kussak, Carl-Axel Nilsson, Barbro Andersson, Jim Langridge

Abstract: A liquid chromatography/electrospray ionization tandem mass spectrometry method is described for the determination of aflatoxins B1, B2, G1 and G2. Samples of naturally contaminated airborne dust and spiked urine were cleaned up on immunoaffinity columns and analyzed by liquid chromatography using either mass spectrometry detection or post-column derivatization with bromine and fluorescence detection. With tandem mass spectrometry, detection limits (S/N = 3) calculated as amount ejected on column were: aflatoxin B1 4 pg, B2 4 pg, G1 5 pg, and G2 10 pg. (10 references)
Aflatoxin B1 Aflatoxin B2 Aflatoxin G1 Aflatoxin G2 HPLC Fluorescence Post-column derivatization Method comparison

"Online Total Arsenic Determination In Urine And Geothermal Fluids By Flow Injection-hydride Generation Atomic Absorption Spectrometry With Microwave Oven Sample Mineralization/oxidation"
Rev. Roum. Chim. 1998 Volume 43, Issue 4 Pages 301-308
Burguera, J.L.;Burguera, M.;Danet, A.F.

Abstract: Samples of 0.1-2.0 mL were subjected to microwave acidic mineralization/oxidation and the continuous hydride generation was carried out by mixing downstream the acidified digest with a 150 g L-1 KI + 5 g L-1 ascorbic acid prereducing solution and thereafter with a 1.0% w/v sodium tetrahydroborate(III) solution The detection limits were of 0.2 ng of arsenic. The relative standard deviation (RSD) of the method obtained in ten replicate analyzes of urine and geothermal fluids spiked with arsenic species varied from 2.5 to 4.5%. Recovery values of the arsenic species were in the range 101-102%. This method is applicable to the determination of total arsenic in the urine of unexposed and exposed subjects.
Arsenic, total Spectrophotometry Sample preparation Microwave

"Phosphorescence In Liquid Solutions. A Promising Detection Principle In Liquid Chromatography And Flow Injection Analysis"
Trends Anal. Chem. 1984 Volume 3, Issue 10 Pages 259-265
C. Gooijer, N. H. Velthorst and R. W. Frei

Abstract: The detection technique described is based on the room-temp. phosphorescence of biacetyl in various eluents (which must be deoxygenated). Such a detection system can be operated in the sensitized- or quenched-phosphorescence mode, the latter being especially suitable for non-absorbing analytes in ion chromatography. As examples of applications of this technique, reversed-phase chromatograms are reproduced for Aroclor 1221 and Halowax 1099, with both modes of detection, and these are compared with chromatograms obtained for the same materials with u.v. detection. Reversed-phase chromatograms are also shown for Halowax 1001 in urine, with sensitized- and quenched-phosphorescence detection, and for the separation of some thiourea derivatives, with quenched-phosphorescence detection. A block diagram is shown of the flow injection system used in these studies.
Halowax 1001 HPIC HPLC Phosphorescence Review Detector

"Ultra-micro-analysis Of Bioactive Substances: An Approach Based On The Development Of Highly Selective Fluorogenic Reagents"
J. Pharm. Soc. Jpn. 1988 Volume 108, Issue 1 Pages 22-38
OHKURA YOSUKE

Abstract: A series of mono- and di-functional fluorogenic reagents has been developed for the selective derivatization of various bioactive substances and as enzyme substrates. These have been used for fluorimetric determination and for HPLC with pre- or post-column derivatization of the substances in biological materials. Methods are described for HPLC of neuraminic acids in serum, of catecholamines in plasma and urine, of peptides in, e.g., rat brain, of reducing sugars in serum and urine, of fatty acids in serum, of prostaglandins in seminal fluid and of fluorouracil in serum.
Acids, fatty Catecholamines Fluorouracil Neuraminic acids Peptides Prostaglandins Sugars, reducing HPLC Fluorescence Post-column derivatization

"Clenbuterol Residue Analysis By HPLC - HPTLC In Urine And Animal Tissues"
Z. Lebensm. Unters. Forsch. 1989 Volume 189, Issue 2 Pages 128-131
Jean-Marie Degroodt, Brigitte Wyhowski de Bukanski, Hedwig Beernaert and Dirk Courtheyn

Abstract: Tissue samples were digested with subtilisin A at 55°C for 1 h in 0.2 M Tris buffer of pH 8 containing 0.1 M CaCl2. The mixture was centrifuged, the solid was washed with more buffer and the supernatant solution were combined. This solution, or a diluted urine sample, was adjusted to pH 10 with NaOH and applied to a Chem Elut CE 1020 column; after 15 min, clenbuterol was eluted with hexane (three portions) and extracted from the eluate into 0.01 M HCl. The resulting solution (100 µL) was analyzed by HPLC on a column (25 cm x 4 mm) of LiChrosorb RP-8 (10 µm), with 0.01 M Na acetate (pH 3.5) - acetonitrile (3:7) as mobile phase (1 mL min-1) and post-column derivatization by adding NaNO2 - HCl (cooled in ice), ammonium sulfamate and N-(1-naphthyl)ethylenediamine with product determination at 500 nm. The calibration range for clenbuterol was 5 to 100 ng mL-1 and the detection limit was 2 ng. Recoveries ranged from 70 to 73% for tissues and from 85 to 90% for urine. The results were confirmed by high performance TLC.
Clenbuterol HPLC Buffer Dilution Column Post-column derivatization Calibration Detection limit

"Use Of 4-chloro-5,7-dinitrobenz-2,1,3-oxadiazole In Flow Injection Analysis Of Substituted Hydrazines"
J. Anal. Chem. 1996 Volume 51, Issue 7 Pages 657-662
M. I. Evgen'ev, S. Yu. Garmonov, I. I. Evgen'eva, and G. K. Budnikov

Abstract: A 1:4 mixture of 30% TCA and the sample (blood plasma, urine or an aqueous solution of a drug) was centrifuged and the supernatant liquid was mixed with 0.5 mL of buffer solution (pH 5.5) and DMSO. The hydrazine derivative concentration was found by FIA with 20 mM 4-chloro-5,7-dinitrobenz-2,1,3-oxadiazole in acetonitrile as the reagent and detection at 510 nm. Beer's law was obeyed for ~0.1-2.5 µg/ml of common hydrazine derivatives. Ammonia, amines, amino-acids, NaCl, sodium phosphate and KCl did not interfere.
Hydrazine Spectrophotometry Interferences

"Evaluation Of Focused Ultrasound And Ozonolysis As Sample Treatment For Direct Determination Of Mercury By FI-CV-AAS. Optimization Of Parameters By Full Factorial Design"
Ultrason. Sonochem. 2006 Volume 13, Issue 1 Pages 98-106
J.L. Capelo, C. Maduro and A.M. Mota

Abstract: Different oxidation methodologies based on ozone and focused ultrasound for the degradation of organic matter and organic-mercury compounds (spiked) present in human urine are discussed. Inorganic and total mercury can be determined in human urine. A flow-injection cold-vapor atomic absorption spectrometer system was used for mercury measurements. Optimization of cold vapor generation was performed with NaBH4 and SnCl2. A two-level full factorial design (24) was applied to understand the cross-effects among the variables influencing the degradation of organic-mercurials and organic matter in urine by KMnO4/HCl/focused ultrasound, namely, KMnO4 and HCl concentration, ultrasonication time and ultrasonication amplitude. Optimization results showed that all variables were significant. New trends in the application of focused ultrasound and ozone are highlighted. As a result of the optimization procedure, one simple, rapid and accurate method was developed for the determination of total mercury in urine samples. The method is based on the ultrasound assisted degradation of organo-mercurials and organic matter in urine in the presence of KMnO4/HCl/Focused Ultrasound. The procedure can be accomplished within 3 min, using 50% sonication amplitude provided by a probe ultrasonic device (63 W maximum output power, 22.5 kHz frequency). The method was applied to measure the mercury content in spiked urine from different non-exposed volunteers.
Mercury Spectrophotometry Optimization Interferences Method comparison Ultrasound

"Fluorescence Analysis For P-Hydroxymethamphetamine In Urine By HPLC With Post-Column Reaction"
J. Liq. Chromatogr. Relat. Technol. 2005 Volume 28, Issue 19 Pages 3099-3108
Noriyuki Kato, Susumu Fujita, Hiroaki Kubo, Hiroshi Homma

Abstract: A high selectivity analytical method for p-hydroxymethamphetamine (pOHMA) in urine is presented. After extraction, the analyte was analyzed by high performance liquid chromatography with post-column oxidation using potassium hexacyanoferrate(III) and sodium hydroxide to detect the fluorophor of pOHMA. The recovery of pOHMA is 86.5%, and the calibration curve for pOHMA is linear in the range of 5-75 µg/mL (r2=0.997). The coefficients of variation determined for spiked samples are 2.2% for 10 µg/mL and 2.3% for 5 µg/mL pOHMA (each n=5), and the detection limit for pOHMA is 1 µg/mL (20 ng; S/N=3). Analysis for pOHMA in forensic samples is performed successfully, without interference from endogenous fluorophors, yielding concentrations in the appropriate range for methamphetamine abusers.
p-Hydroxymethamphetamine Fluorescence HPLC Post-column derivatization Interferences

"Time-based On-line Preconcentration Cold Vapour Generation Procedure For Ultra-trace Mercury Determination With Inductively Coupled Plasma Atomic Emission Spectrometry"
Anal. Bioanal. Chem. 2004 Volume 379, Issue 5-6 Pages 764-769
Aristidis N. Anthemidis, George A. Zachariadis, Christos E. Michos and John A. Stratis

Abstract: A time-based sequential dispensing on-line column pre-concentration procedure for mercury determination at trace levels by cold vapor generation inductively coupled plasma atomic emission spectrometry (CV-ICP-AES), by means of a unified module of a pre-concentration column and a gas-liquid separator (PCGLS) is described. The complex of mercury formed on-line with ammonium pyrrolidine dithiocarbamate (APDC) is retained on the surface of the hydrophobic poly(tetrafluoroethylene) (PTFE) turnings, which are packed into the lower compartment of the PCGLS. Subsequently, mercury vapor is generated directly on the PTFE turnings by reductant SnCl2 and separated from the liquid mixture via the PCGLS by argon purge gas. The outlet of the PCGLS is connected directly to the torch adapter of the plasma without the normal spray chamber and nebulizer. With 60-s pre-concentration time and 12.0 mL min-1 sample flow rate, the sampling frequency is 30 h-1. The calibration curve is linear over the concentration range 0.02-5.0 µg L-1, the detection limit (cL) is 0.01 µg L-1 and the relative standard deviation (sr) is 3.1% at the 1.0 µg L-1 level. The proposed method was evaluated by analysis of BCR CRM 278 (Mytilus Edulis) reference material and applied to the determination of total mercury in digested urine, blood and hair samples.
Mercury Spectrophotometry Solid phase extraction Reference material Phase separator Preconcentration Dithiocarbamate

"Determination Of Kanamycin Using Flow Injection Analysis Coupled With Resonance Rayleigh Scattering Detection"
Bull. Chem. Soc. Jpn. 2006 Volume 79, Issue 2 Pages 247-251
Xiaoli Hu, Shaopu Liu and Zhongfang Liu

Abstract: A flow injection analysis (FIA) method coupled with resonance Rayleigh scattering (RRS) detection for the determination of kanamycin sulfate (KANA) was developed. The method is based on the ion-association reaction of KANA with acid triphenylmethane dyes such as aniline blue W. S (AB) and methyl blue (MB) by virtue of electrostatic and hydrophobic interaction forces, which results in a significant enhancement of RRS intensity; their maximum scattering peaks are all at 346 nm. The optimum conditions of the reactions and the flow-through parameters including the length of reaction tubing, the flow rate of the carrier stream and the sample injection volume are discussed in this paper. Under the optimum experimental conditions, the linear ranges for both systems are 0.02-12.0 µg mL-;1. The detection limits (3s) are 4.2 ng mL-;1 for the AB system and 5.0 ng mL-;1 for the MB system and the relative standard deviation for 9 replicate measurements of 2.0 µg mL-;1 KANA solution was 1.1%. The proposed method was successfully applied to the determination of KANA in commercial KANA injection, urine and serum samples, and the sample throughput was 30 h-;1.
Kanamycin Raman Optimization

"Micro Flow Injection Analysis Combined With A Separation Technique For The Urinary Glucose Assay"
Anal. Sci. 2006 Volume 22, Issue 1 Pages 99-103
Qiong JIA, Tomoko MATOBA, Syouhei NISHIHAMA and Kazuharu YOSHIZUKA

Abstract: A urinary glucose assay has been investigated, employing a µflow injection analysis (µFIA) combined with a separation technique of glucose from the analyte. The adsorption part using activated alumina for the glucose in the analyte can be successively integrated onto a µFI chip. The selective adsorption-desorption of glucose in the artificial urine can progress on the adsorption part. Along with this selective pre-concentration of glucose, the typical FI peak of glucose can be obtained just by feeding the sample and deionized water as an elutant sandwiched with the reagent on the carrier stream. The glucose concentration in artificial urine can be quantitatively determined with the present µFIA system, while the interference of other components coexisting in urine occurs in the case of the conventional FIA system without any separation part. The described method serves as a template for improving the selectivity for the analyte in the multi-component system.
Glucose Spectrophotometry Activated alumina Microfluidic Interferences Preconcentration

"Direct Determination Of Copper In Urine Using A Sol–gel Optical Sensor Coupled To A Multicommutated Flow System"
Anal. Bioanal. Chem. 2004 Volume 380, Issue 1 Pages 108-114
Paula C. A. Jer&oacute;nimo, Alberto N. Ara&uacute;jo, M. Concei&ccedil;&atilde;o B. S. M. Montenegro, Celio Pasquini, Ivo M. Raimundo Jr

Abstract: In this work, a multicommutated flow system incorporating a sol-gel optical sensor is proposed for direct spectrophotometric determination of Cu(II) in urine. The optical sensor was developed by physical entrapment of 4-(2-pyridylazo)resorcinol (PAR) in sol-gel thin films by means of a base-catalyzed process. The immobilized PAR formed a red 2:1 complex with Cu(II) with maximum absorbance at 500 nm. Optical transduction was based on a dual-color light-emitting diode (LED) (green/red) light source and a photodiode detector. The sensor had optimum response and good selectivity towards Cu(II) at pH 7.0 and its regeneration was accomplished with picolinic acid. Linear response was obtained for Cu(II) concentrations between 5.0 and 80.0 µg L-1, with a detection limit of 3.0 µg L-1 and sampling frequency of 14 samples h-1. Interference from foreign ions was studied at a 10:1 (w/w) ion:Cu(II) ratio. Results obtained from analysis of urine samples were in very good agreement with those obtained by inductively coupled plasma mass spectrometry (ICP-MS); there was no significant differences at a confidence level of 95%.
Copper Copper(II) Sensor Sol-gel Complexation Light emitting diode Photodiode Selectivity Linear dynamic range Detection limit Interferences Statistics