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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Dilution

Classification: Manifold process -> Dilution

Citations 117

"An Automated Flow Injection Analysis Procedure For The Determination Of Reducing Sugars By DNSA Method"
J. Food Sci. 2001 Volume 66, Issue 3 Pages 407-411
P. Cañizares-Macías, L. Hernández-Garciadiego, and H. Gómez-Ruíz

Abstract: A nonenzymatic spectrophotometric method, coupled to an automatic system of standard additions, based on the reaction with 3,5-dinitrosalicylic acid (DNSA) is described. In a system based on an exhaustive reaction, sample volumes are introduced together with calibration solutions, thus the calibration is performed in a nonsegmented flow system. Homogenization of the sample/standard/carrier takes place in the calibration loop. Later, it is injected in the flow injection analysis system, where the reaction with DNSA occurs, to obtain 3,5-diaminosalicylic acid which is measured spectrophotometrically. With the proposed method, it is possible to eliminate the Rochelle: salt, sodium and potassium tartrate, phenol and sodium bisulfite of the principal reagent. Sample throughput was 11 samples/h and precision, expressed as relative standard deviation, was 2.3%.

"A Robust Multisyringe System For Process Flow Analysis. 1. Online Dilution And Single Point Titration Of Protolytes"
Analyst 1999 Volume 124, Issue 9 Pages 1373-1381
Fernando Albertús, Burkhard Horstkotte, Andreu Cladera and Víctor Cerdá

Abstract: A robust multichannel manifold involving a multisyringe piston pump used for performing process flow analysis is proposed. The simultaneous sequential determination of two analytes with a sampling frequency of 97 injections per hour is demonstrated. A robust and rapid continuous flow titration system, including a predilution step, was developed. A quantitative dilution, avoiding the need for diluting the standards too, is achieved in two steps by first splitting the concentrated sample stream and further dilution in a mixing chamber. A wide range of dilution grades (from 80 to 1150) can be easily implemented by software instructions, without the necessity of mechanical reconfiguration of the manifold. The resulting system gives medium or low dispersion peak signals with a sampling frequency of over 75 injections per hour for off-line diluted samples, and more than 33 injections per hour for concentrated samples. The proposed assemblage allows the automation of the single point flow injection titration procedure for the assay of acids and bases in concentrated process solutions. Recoveries of 97.5-103% were found with a maximum RSD value of 5%.
Acids Bases

"Development Of The Continuously Variable Volume Reactor For Flow Injection Analysis Part 1. Design, Capabilities And Testing"
Anal. Chim. Acta 2002 Volume 455, Issue 2 Pages 287-304
Linda L. Lipe, Suzanne M. Purinton, Elizabeth Mederios, C. Chad Harrell, Cynthia Efta, Melissa Murray, Meredith Wood, Ray-Bernard Portier and Stuart J. Chalk

Abstract: A new apparatus for mixing sample and reagent in flow injection analysis (FIA) is described. The continuously variable volume reactor (CVVR) replaces the conventional mixing coil in a flow injection (FI) manifold to provide mixing and dilution. A linear actuator motor allows control of the chamber volume via LabVIEW software. The chamber volume can be incremented in steps of I µL over the range 68-1704 µL. In addition, the chamber has an integral variable-speed stirring unit that is also under computer control. Experiments were performed to evaluate the dispersion characteristics of this new device, evaluate the volume reproducibility, and understand the mixing characteristics. Use of the chamber is shown in the determination of iron(II) in pond water, and in NIST SRM 1643d with excellent results and a detection limit of 3.7 µg/l iron(II). Advantages of the CVVR and future research activities using the device are discussed.
Iron(2+) NIST 1643 Spectrophotometry

"Sequential Injection Analysis As A Tool For In Situ Monitoring Of Fe(II), Fe(III), NO3- And NO2- In Natural And Waste Waters"
Anal. Chim. Acta 2001 Volume 438, Issue 1-2 Pages 39-48
Cristiane X. Galhardo and Jorge C. Masini

Abstract: This paper presents a sequential injection analysis (SIA) system for sequential monitoring of Fe(II) and Fe(III), or NO3- and NO2- with typical concentrations of natural and waste waters. Determination of nitrite was based on the Griess-Ilosvay reaction, while the Fe(II) determination was based on the reaction with 1,10-phenantroline. Determination of Fe(III) and NO3- were performed after their reduction, respectively, in Jones and copperized cadmium columns, using forward and reversal flow directions. Tangential filtration permitted the application of the methodology for determination of dissolved species in aquatic suspensions containing particulate matter and sediments. The stability of the analytical curves was verified over periods of 4-5 days. Quantification limits for NO2- and NO3- were 0.01 and 0.02 mg L-1 N, respectively. For Fe(II) and Fe(III) the quantification limits were 0.05 and 0.1 mg L-1, respectively, with a sampling frequency of 20 h-1. The influence of sulfides and natural organic matter on the performance of the reducing columns were evaluated, as well as the use of regeneration solutions.

"Spectrophotometric Determination Of Acid Volatile Sulfide In River Sediments By Sequential Injection Analysis Exploiting The Methylene Blue Reaction"
Talanta 2001 Volume 53, Issue 4 Pages 843-850
Marcelo S. P. Silva, Ivone S. da Silva, Gilberto Abate and Jorge C. Masini

Abstract: This paper demonstrates the application of sequential injection analysis to perform sulfide determination using the methylene blue chemistry, based on two reagents: 3.63 mmol L-1 N,N dimethyI-p-phenylene diamine hydrochloride in 1.1 mol L-1 HCl solution and 19 mmol L-1 FeCl3, also in 1.1 mol L-1 HCl. These solutions are aspirated inside the holding coil of the sequential injection system as two reagent zones sandwiching the sample zone. Under optimized conditions, the detection limit was calculated at 40 µg L-1 S2-, with a linear dynamic range from 0.05 to 2 mg L-1 S2-. This linear range can be extended up to 32 mg L-1 using in-line dilution for sulfide concentrations greater than 2 mg L-1. The robust characteristic of the SI system with syringe pump leads to very stable analytical curves (precision of 4%) minimizing the laborious preparation of sulfide standards. The method was applied in the determination of acid volatile sulfide in river sediments. (C) 2001 Elsevier Science B.V. All rights reserved.

"Determination Of Cu, Pb, Cd, And Zn In River Sediment Extracts By Sequential Injection Anodic Stripping Voltammetry With Thin Mercury Film Electrode"
Fresenius J. Anal. Chem. 2000 Volume 367, Issue 3 Pages 284-290
C. L. da Silva, J. C. Masini

Abstract: Determination of Cu, Pb, Cd and Zn was performed in sediment extracts obtained according to the three steps sequential extraction procedure proposed by the European Community Standards, Measurements and Testing Program. The metal content was determined by anodic stripping voltammetry with a thin mercury film electrode controlled by a sequential injection (SIA) system. The proposed method improved the reproducibility of conventional anodic stripping voltammetry, as well as the sample throughput, allowing analysis of 30 to 45 samples per hour. The influence of flow rate and sample volume was studied to achieve an adequate sensitivity for the leachate studied. No interferences due to adsorption of organic matter, colloids, or complexes with slow rate of dissociation were observed. The intermetallic formation of Cu-Zn was avoided by forming the mercury film in presence of Ga(III) ions in the SIA system, resulting in low consumption of reagent in comparison to flow injection or continuous flow systems. Results were in good agreement with those obtained by Induced Coupled Plasma - Atomic Emission Spectroscopy (ICP- AES).

"A New Sample-injection/sample-dilution System For The Flow Injection Analytical Technique"
Anal. Chim. Acta 1999 Volume 381, Issue 2-3 Pages 287-295
Milko Novic, Iñaki Berregi, Angel Ríos and Miguel Valcárcel

Abstract: A new sample-injection/sample-dilution system for the flow injection analytical technique is proposed. The system is based on two variable-speed computer-controlled peristaltic pumps and a specially designed commutator located at the merging point. One of the pumps delivers a sample and the other a carrier solution. The pumps are run in such a way that the total flow rate after the merging point remains permanently constant. The volume of the injected sample is determined by the time the sample delivering pump is on, whilst the dilution of the sample is determined by relative flow rates of sample and carrier solutions. Two additional possibilities are offered by the proposed system. Firstly, the volume of the injected sample plug can be varied in a simple way, and secondly, for the first time, the injection of a sample plug having an exactly predetermined concentration profile for the measured analyte at the merging point can be carried out. By introducing a third pump delivering a standard solution of the measured species, the system is able to perform a quantitative determination of an analyte, either by the standard addition method or by forming a calibration curve using only one standard solution.
Spectrophotometry

"Determination Of Molybdenum, Antimony And Tungsten At Sub Mu G G (super -1) Levels In Geological Materials By ID-FI-ICP-MS"
Geostand. Newsl. 1999 Volume 23, Issue 2 Pages 137-148
Akio Makishima and Eizo Nakamura

Abstract: We have developed a rapid and accurate method for the determination of Mo, Sb and W in geological samples using isotope dilution inductively coupled plasma-mass spectrometry with a flow injection system (ID-FI-ICP-MS). The chemical procedure requires HF digestion of the sample with a Mo-Sb-W mixed spike, subsequent evaporation and dissolution of Mo, Sb and W from Mg and Ca fluorides with HF. Recovery yields of Mo, Sb and W in the extraction were > 94% for samples of peridotite, basalt and andesite composition, with the exception of W in samples of peridotite composition for which recovery was 81%. No matrix effects were observed in the determination of the isotope ratios of Mo, Sb and W in solutions prepared from peridotite, basalt and andesite samples down to a dilution factor of 100. Detection limits of Mo, Sb and W in silicate materials were at the several ng g-1 level. Analysis of the silicate reference materials PCC-1, DTS-1, BCR-I, BHVO-1, AGV-1 from the US Geological Survey and JP-1, JB-1, -2, -3, JA-1, -2, and -3 from the Geological Survey of Japan as well as the Smithsonian reference Allende powder yielded reliable Mo, Sb and W concentrations. The repeatability in the analysis of basalts and andesites was < 9%. This technique requires only 0.2 mL sample solution, and is therefore suitable for analyzing small and/or precious samples such as meteorites, mantle peridotites and their mineral separates.

"Flow Injection Analysis. 6. The Determination Of Phosphate And Chloride In Blood Serum By Dialysis And Sample Dilution"
Anal. Chim. Acta 1976 Volume 87, Issue 2 Pages 353-363
Elo H. Hansen and Jaromir Rika

Abstract: The rapid determination of Cl- and inorganic phosphate (Pi) in blood serum based on continuous-flow spectrometry was adapted to flow injection analysis by applying dialysis as well as differential dilution of the injected samples. In addition to the manual injection procedure, an automated microsampling unit was developed and used. By continuous dialysis Cl- could be determined reproducibly at a sampling rate of 125 samples/h at sample volumes of ≤60 µL. A similar sampling rate and high precision were obtained for the determination of Pi by using differential dilution.
Chloride Phosphate Phosphates Blood Serum Clinical analysis Spectrophotometry

"Gradient Techniques In Flow Injection Analysis. Stopped-flow Measurement Of The Activity Of Lactate Dehydrogenase With Electronic Dilution"
Anal. Chim. Acta 1982 Volume 136, Issue 1-2 Pages 101-112
S. Olsen, J. Rika and E. H. Hansen

Abstract: The feasibility of selecting reproducibly a suitable element of the dispersed sample zone in a flow injection system is exploited for stopped-flow measurement of the enzymatic activity of lactate dehydrogenase. By electronic selection of different segments along the gradient and monitoring of the stopped-flow intervals with a computer, this technique can be extended to cover wide concentration ranges while maintaining the inherent high precision of flow injection measurements. This approach is further pursued by designing a general technique for electronic dilution and electronic calibration by which a multipoint calibration curve may be constructed using a single injection of sample material.
Enzyme, lactate dehydrogenase Spectrophotometry

"Extensive Flow Injection Dilution For Inline Sample Pretreatment. Comparison Between Single-stage And Dual Stage Modules"
Anal. Chim. Acta 1988 Volume 207, Issue 1-2 Pages 225-231
M. B. Garn, M. Gisin, H. Gross, P. King, W. Schmidt and C. Thommen

Abstract: Each stage of the dilution module comprises a fixed loop injector, a stirred mixing chamber and a pulse-free pumping system. The dual-stage module is a combination of two single-stage modules with a zone-sampling process as the interface. The precision of both systems is insensitive to flow rate and is better than 2% at dispersion coefficient 106. The dual-stage module gave superior performance over a wide range of dispersion coefficient at higher throughput. However, the single-stage module was sufficient for inline sample pre-treatment for flow injection analyzers as well as other types of chemical analyzer.

"Potentiometric Flow Injection Determination Of Trace Chlorine Based On Its Redox Reaction With An Iron(III)/iron(II) Buffer"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 349-357
Nobuhiko Ishibashi and Toshihiko Imato, Hiroki Ohura and Sumio Yamasaki

Abstract: Sample solution (140 µL) is injected into the water carrier stream (0.71 mL min-1) which then merges with the potential buffer solution (0.71 mL min-1) consisting of 0.01 M Fe(III) - 0.01 M Fe(II) containing 0.3 M KCl and 0.5 M H2SO4. The sample passes through a 90-cm reaction coil, and the change in potential of the flow-through electrode is recorded. The detector comprises a gold-plated oxidation - reduction potential electrode and a Ag - AgCl reference electrode. Calibration graphs are rectilinear for 0.1 to 10 µM-Cl and the detection limit is 50 nM. The coefficient of variation at the 2.5 and 8 or 10 µM levels are 2.5 and 1.1%, respectively. Tolerance limits for co-existing ions are tabulated. Results for two water samples agreed with those obtained by the o-tolidine method.
Chlorine Environmental Electrode Electrode Potentiometry

"In-situ Ethanol Probe Based On Sample Dilution In A Double Membrane System"
Anal. Chim. Acta 1988 Volume 215, Issue 1 Pages 71-77
Carl Fredrik Mandenius

Abstract: An in-situ probe suitable for monitoring ethanol in fermenters or other bioreactors is described. It is constructed with an ethanol-permeable double membrane covering a solid-state tin(IV) oxide sensor for gas detection. A stream of nitrogen is passed between the two membranes in order to dilute the ethanol vapor from the fermenter that has passed through the first membrane, before it reaches the second membrane covering the detector. A 100-fold dilution was obtained at a flow rate of 30 mL min-1 of the diluent gas. The delay time was less than 5 min to obtain 80% of maximum response.
Ethanol Fermentation broth Biotechnology Conductometry Electrode

"Separation Of Rhenium By Extraction With Crown Ethers And Flow Injection Extraction-spectrophotometric Determination With Brilliant Green"
Anal. Chim. Acta 1990 Volume 232, Issue 1 Pages 287-292
Hideko Koshima and Hiroshi Onishi

Abstract: Rhenium solution (20 µg) were prepared in 2 M KOH - 10 mM K Na tartrate (10 to 30 ml), and the Re(VII) was extracted into a 10 mM dicyclohexano-18-crown-6 in 1,2-dichloroethane (5 ml, then 2 ml). The combined extracts were diluted with hexane, and the Re(VII) was back-extracted into 0.2 M phosphate buffer of pH 6.0 (6 ml, then 3 ml). The Re in the buffer was determined by flow injection, with 4 reagent lines, viz, buffer (0.4 mL min-1), water (0.4 mL min-1), ethanolic 0.15% C. I. Basic Green 1 and benzene (0.2 mL min-1). The absorbance of the benzene extract of the complex was measured at 640 nm. The calibration graph was rectilinear for up to 1.5 mg L-1 of Re(VII) in aqueous solution There was serious interference by NO3- and ClO4-; the former could be prevented by decomposition with formic acid. Large amounts of Mo(VI) did not interfere, so the method could be applied directly to, e.g., molybdenite.
Rhenium Spectrophotometry Sample preparation

"Kinetic Determination Of Sulfonamides At The Millimolar Level By The Continuous Addition Of Reagent Technique"
Anal. Chim. Acta 1990 Volume 237, Issue 2 Pages 353-359
M. M&aacute;rquez, M. Silva and D. P&eacute;rez-Bendito

Abstract: A sulfonamide solution was mixed with 5 mM 1-naphthol in ethanol and 1.0 M acetic acid - Na acetate buffer (pH 4.15) and the mixture was diluted with water. The reaction was developed by continuous addition of 1 M NaNO2 at 0.5 mL min-1 with stirring at 200 rpm. The production of an azo dye was monitored at 470 nm. The calibration graph was rectilinear from 3 to 30 µM. The coefficient of variation for 18.7 µM-sulfonamide was 1.0% (n = 11) and the sampling rate was 25 h-1. The detection limit was 1.5 to 2.0 µM. The method is more sensitive than a reported flow injection method and more rapid than the conventional photometric micellar method. The technique was used for the determination of sulfonamides in pharmaceuticals.
Sulfonamides Pharmaceutical

"Characterization And Application Of Precise And Robust Flow Injection Analysers For Online Measurement During Fermentations"
Anal. Chim. Acta 1991 Volume 247, Issue 1 Pages 45-50
S. Benthin, J. Nielsen and J. Villadsen

Abstract: Automated flow injection analyzer.s were developed for the online measurement of glucose, lactic acid and biomass during fermentation in which biomass concentration. were determined by absorbance measurements. Glucose and lactate were oxidized enzymatically and the H2O2 formed was detected by chemiluminescence with luminol. The performance of the enzyme reactors and the chemiluminescence detector was considered. Incorporation of gradient dilution systems in the glucose and lactate analyzer.s ensured that they operated in linear ranges. All three analyzer.s were stable and had excellent precision.
Glucose Lactic acid Chemiluminescence

"Monitoring Of Substrates And Products During Fed-batch Penicillin Fermentations On Complex Media"
Anal. Chim. Acta 1991 Volume 249, Issue 1 Pages 123-136
Lars H. Christensen, Jens Nielsen and John Villadsen

Abstract: An automated monitoring system is described (with diagrams) comprising a membrane sampling module for fermentation media, flow injection analysis (FIA) systems for ammonium and glucose determination and exhaust gas analysis system for monitoring O and CO2 and a microcomputer for data acquisition. The O is determined paramagnetically and CO2 determined by IR absorbance. The FIA system for glucose contains a mixing chamber for dilution of the sample and a column of immobilized glucose oxidase. Detection is by chemiluminescence. The RIA system for NH4+ contains a mixing chamber and a gas diffusion device. Cresol red is used as pH indicator and spectrophotometric detection is at 565 nm. The monitoring system was applied to penicillin V fermentation broth.
Penicillin V Glucose Fermentation broth Chemiluminescence Spectrophotometry

"Automatic Calibration And Dilution In Unsegmented Flow Systems"
Anal. Chim. Acta 1992 Volume 264, Issue 2 Pages 265-273
M. Agudo, A. R&iacute;os and M. Valc&aacute;rcel

Abstract: Automatic preparation of calibration solution was incorporated into a manifold by a switching-diverting valve, thus the calibration and determination steps were coupled and automated. The method was applied in the determination of NO2- with spectrophotometric monitoring at 540 nm using sulfanilamide and N-(1-naphthyl)ethylenediamine. The system may be useful in process control. An open-closed flow system allowing variable volumes of standard calibration solution to be introduced and automatically diluted was used to carry out automatic calibrations in unsegmented flow systems. A dilution loop was thus established in which its final homogenized volume was used as diluted sample or calibrant solution in the main flow system. The performance of the dilution loop was tested both in injection and in completely continuous-flow systems and was found to be appropriate for anal. process control.
Nitrite Spectrophotometry

"Use Of Submicrolitre-volume Samples For Extending The Dynamic Range Of Flow Injection Flame Atomic Absorption Spectrometry"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 85-95
I. L&oacute;pez Garc&iacute;a, P. Vi&ntilde;as, N. Campillo and M. Hern&aacute;ndez C&oacute;rdoba*

Abstract: Three computer-controlled flow injection manifolds were compared for extending the linear range of flame-AAS. All manifolds were based on metering very small volumes into a slow moving carrier. At the end of the injection the flow rate of the carrier was increased. The manifolds were equipped with an additional channel to compensate for the difference between the flow delivered by the pump and the nebulizer uptake rate. The most satisfactory results were obtained by performing a single metering stage with a peristaltic pump fitted with a 0.38 mm i.d. bore tube. The exact position of the rollers at the beginning of the metering stage was controlled by a simple optical device. Volumes as low as 0.02 µL were injected into the system by using a 0.15 s metering time at 0.56 rpm. Dilutions of 20 000-fold were achieved with a repeatability of ±1.1-3.3%.
Magnesium Spectrophotometry

"Flow System Based On A Binary Sampling Process For Automatic Dilutions Prior To Flame Atomic Spectrometry"
Anal. Chim. Acta 1996 Volume 323, Issue 1-3 Pages 47-53
Maria Fernanda Gin&eacute;, Ana Paula Packer, Telma Blanco and Boaventura Freire dos Reis

Abstract: A microcomputer-controlled flow system to perform automatic dilutions exploiting a binary sampling process is proposed. Introduction of precise volumes of sample and solvent was achieved by solenoid valves. The possibility to get different volumetric fractions was realized by software, which defined the time delays of the valves and could be used, e.g., for samples with analyte concentrations exceeding the analytical range. A noteworthy feature is that sample and standards processing is not necessarily the same. The analytical performance was exhaustively investigated, in particular the precision of standard measurements generated after application of different dilutions, or repeatability of results of 20 and 40 times diluted real sample solutions. The feasibility of the approach was demonstrated by the on-line automatic dilution of plant digests for determining Ca and K by flame atomic absorption and emission spectrometry. Precision of measurements performed on a solution produced by the automatic 10-fold dilution of a 100 mg/l solution was characterized by a RSD < 1%. Accuracy was assessed by analyzing vegetal reference materials after diluting 10 or 20 times. Results were in agreement at 95% significance level with the certified values. Comparison of automatic and manual dilutions by using a paired t-test on a set of samples with varying composition presented no statistical difference at the 95% significance level.
Spectrophotometry

"Automatic Multicommutation Flow System For Wide Range Spectrophotometric Calcium Determination"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 45-53
F&aacute;bio R. P. Rocha, Patr&iacute;cia B. Martelli, Rejane M. Frizzarin and Boaventura F. Reis*

Abstract: An automatic flow system based on multicommutation concept is proposed to widen the linear concentration range for spectrophotometric calcium determination The flow network was build up with three way solenoid valves to permit implementation of different sample processing conditions to achieve limited, medium and large dispersion degree without modification of the manifold configuration. Dilutions were carried out by changing both sampled volume and the analysis path length or applying zone sampling approach. The software was developed to control all steps of sample processing and to allow changing the manifold configuration to obtain suitable sample dilution This condition was attained with up to 3 trials. A linear response from 0.250 to 1000 mg L-1, and a detection limit of 7 µg L-1 (99.7% confidence level) were achieved. The relative standard deviation was 0.83% (n = 10) or better. The sampling rate was ~60 h-1 and 0.27 µg of the chromogenic reagent (3,3'-bis[N,N-bis(carboxymethyl)aminomethyl]-o-cresolphthalein) was consumed per determination The procedure was applied to calcium determination in waters, plant materials, milk, antacid tablets, fertilizers and calcareous rocks. The results were in agreement with certified values or with those obtained with flame atomic absorption spectrophotometry at a 95% confidence level.
Calcium Environmental Plant Cow Pharmaceutical Commercial product Calcareous Spectrophotometry

"Simultaneous Multiple Injection In Monosegmented Flow Analysis"
Anal. Chim. Acta 1998 Volume 371, Issue 2-3 Pages 317-324
Vanessa O. Brito and Ivo M. Raimundo Jr.*

Abstract: A flow approach for simultaneous multiple injection (SMI) in monosegmented flow anal. (MSFA) is described. In this approach, the sample and the reagent (or other solution, such as a diluting fluid) are simultaneously injected into the reaction coil of a monosegmented flow analyzer. The monosegment is homogenized while it is carried towards the detector. The sample dilution procedure is not based on a gradient concentration. pattern and dilution factors up to 150 were obtained by using hydrodynamic sampling. The system was applied to perform sample dilution in the determination of glucose in blood plasma. The results show good correlation with those obtained by the Clinical Hospital of UNICAMP. The SMI approach was also applied to add reagent to the sample in nitrite determination in natural water, providing a methodology that has a sampling frequency of 72/h, a relative standard deviation of <2%, at 60 µg/L N-NO2-, a linear response range up to 260 µg/L and a 2s limit of detection of 5 µg/L N-NO2-. Thus, the sensitivity is close to that of the manual reference method. Recovery tests carried out with sea water samples also showed that MSFA overcomes the Schlieren effect, without needing any special procedure.
Glucose Nitrite Blood Plasma Sea

"Continuous Sample Recirculation In An Opened-loop Multicommutated Flow System"
Anal. Chim. Acta 1998 Volume 377, Issue 1 Pages 103-110
Rui A. S. Lapa*, Jos&eacute; L. F. C. Lima, Boaventura F. Reis and Jo&atilde;o L. M. Santos

Abstract: A continuous circulating multicommutated flow system based on an opened-loop configuration is proposed. The sample is inserted into the flow system and continuously recirculated until a suitable dilution level is attained, which is permanently surveyed by including the detector in the circular reactor. A continuous removal of the highly dispersed front and trailing zones of the sample plug improves dilution efficiency. The chromogenic reagent used as carrier solution is permanently renewed, which contributes to a constant renewal of the reaction zone increasing the reaction rate by reducing its dependence on the dispersion at the sample/reagent interface. The developed methodology was tested in the determination of chloride in parenteral solutions by the formation of the Fe (III) thiocyanate complex with expansion of the linear range of determination up to 10,000 mg L-1. Results were reproducible (relative standard deviation <1.8%) and in agreement with those obtained by the conventional procedure.
Chloride Parenteral Fluid Spectrophotometry

"Continuous-dilution Calibration Technique For Flame Atomic Absorption Spectrophotometry"
Talanta 1984 Volume 31, Issue 1 Pages 9-14
J. F. Tyson and J. M. H. Appleton

Abstract: The rapid, automatic calibration procedure presented is based on a flow injection technique (mixing-chamber gradient method); it requires no curve-fitting approximations, and extends over the whole working concentration. range of the analyte, irrespective of the shape of the conventionally obtained calibration graph. The theory of the method and a schematic diagram of the apparatus are given. Results for the determination of Mg, Cr and Ni are presented and discussed. With well designed apparatus, deviations of <1% should be attainable; deviations of <4% were obtained.
Cadmium Magnesium Nickel Spectrophotometry

"Flow Injection Analysis With Multidetection As A Useful Technique For Metal Speciation"
Talanta 1986 Volume 33, Issue 3 Pages 199-202
J. Ruz, A. Rios, M. D. Luque de Castro and M. Valcarcel

Abstract: A flow injection system is described in which the simultaneous and separate determination of Cr(VI) and Cr(III) is effected with use of a single-beam spectrophotometer. The method involves injection of the reagent (1,5-diphenylcarbazide in aqueous ethanol plus Ce(IV) in dilute HNO3) into the sample solution, which acts as the carrier, and the reaction product is monitored at 540 nm. The max. ranges of the calibration graphs are from ~0.1 to 1.2 µg mL-1 for Cr(VI) and 0.5 to 6.0 µg mL-1 for Cr(III). The sequence of flow injection operations is explained, and details of normal, amplification and dilution procedures are presented.
Chromium(III) Chromium(VI) Water Spectrophotometry

"Evaluation Of The Analytical Use Of The Manganese-catalysed Malachite Green - Periodate Reaction By The Stopped-flow Technique"
Talanta 1989 Volume 36, Issue 11 Pages 1091-1094
M. C. Quintero, M. Silva and D. Perez-Bendito

Abstract: Sample solution contained 2 to 200 ng mL-1 of Mn(II) and 0.1 M NaIO4 (0.7 ml); the reagent solution consisted of 0.22 mM malachite green (2.5 ml) and acetate buffer (pH 3.8; 4 ml). The solution were diluted to volume and mixed, and the decrease in absorbance was measured at 615 nm. The effect on reaction rate of temp., concentration. of reagents and pH were investigated; the detection limit depended on the presence of the activator nitrilotriacetic acid. The calibration graphs were rectilinear from 0.1 to 15 and 0.5 to 100 ng mL-1 of Mn(II), and precision was 2% (n = 11). The proposed method was more sensitive and rapid than reference batch and flow injection methods.
Manganese

"Direct FIA - AS Determination Of Potassium And Magnesium In Cement Samples By Use Of The Slurries Approach"
Talanta 1993 Volume 40, Issue 1 Pages 107-112
R. Martinez-Avila, V. Carbonell, A. Salvador and M. de la Guardia

Abstract: Cement (50 mg) was dispersed in 0.13 M HNO3 and 100 µL of this slurry was injected into a double channel flow injection analysis manifold simultaneously with 100 µL of a 10% La buffer solution (prepared from LaCl3.7H2O). This allowed the rapid leaching of K and Mg; if only K was to be determined, the slurry was dispersed in water without acid. The manifold included a well-stirred mixing chamber which provided adequate online dilution prior to flame emission or absorbance measurements. The carrier flow rate was 8.4 mL min-1, which allowed a sample throughput of 48 h-1. The dynamic range of the method was up to 30 or 20 µg mL-1 for Mg and K, respectively. The detection limits were 0.15 mg L-1 for K and 0.29 mg L-1 for Mg, corresponding to 0.007% of K2O and 0.01% of MgO in the slurry. For a sample containing 0.54% of K2O and 1.72% of MgO, the coefficient of variation was about 1% (n = 10). The results agreed with those obtained by flame AAS after alkaline fusion, and had better precision.
Potassium Magnesium Commercial product Spectrophotometry Spectrophotometry

"Factorial Design For The Response Exploration Of A Flow Injection System"
Talanta 1995 Volume 42, Issue 5 Pages 701-709
A. Matousek de Abel de la Cruz, J. L. Burguera, M. Burguera and C. Rivas,

Abstract: A factorial composite design was employed for the exploration of the response as a function of the flow rate and length of the dispersion coil of a flow injection system (diagram given) employed for online dilution and determination of Cu by flame-AAS. An empirical response function (RF), which takes into account the peak height and the response time, was employed to evaluate the response. The RF was modified using the RSD in order to discriminate not only from high absorbance and adequate response time, but also for the best precision.
Copper Spectrophotometry

"Online Diluter For Atomic Absorption Spectrophotometry"
Analyst 1982 Volume 107, Issue 1271 Pages 232-234
Michael H. Ramsey and Michael Thompson

Abstract: The short calibration range of atomic-absorption spectrophotometers and the widely varying sensitivities available for various elements tend to complicate the analysis of environmental materials. The complication stems from (a) the wide range of analyte concentrations found, which requires extra dilution for sporadic samples, and (b) the systematic dilution of every sample solution needed when combinations of certain elements are determined. For example, in the analysis of soils for cadmium and zinc, different dilutions are required for the two elements because of their very different abundances, and the absence of medium-sensitivity lines for zinc. These complications do not constitute a problem for small analytical loads. However, in long runs, and especially when automatic systems are employed, the retrospective replacement of out-of-range measurements and the use of two separate dilutions for different elements add substantially to the workload. There are a number of discrete dilution systems available commercially, although we are aware of no previous examples of an on-line continuous dilution system for atomic absorption. Here we describe an on-line diluter that can obviate manual intervention. If a test solution is found to have a concentration above the useful range the flow can be immediately diverted through the diluter to supply a fixed-ratio dilution to the nebuliser. The device described here is hand operated, but could readily be adapted to automatic control. The mixing chamber produces turbulent mixing with minimum flow resistance, which are the conditions required for this application.
Spectrophotometry

"Spectrophotometric Determination Of Nickel(II), Iron(II), Boric Acid And Chloride In Plating Baths By Flow Injection Analysis"
Analyst 1988 Volume 113, Issue 12 Pages 1821-1826
David A. Whitman, Gary D. Christian and Jaromir Ruzicka

Abstract: In one set-up, a two-line system was used for the flow injection determination of Ni(II) and Fe(II); Ni(II) (0.17 to 0.24M) was determined directly by spectrophotometry at 675 nm in the presence of 2.7 to 5.4 mM Fe(II). Bivalent Fe was determined after oxidation by S2O82- to Fe(III) which was then caused to react with SCN- with absorbance measurement of the product at 505 nm. In a second set-up, H3BO3 was introduced to 0.1 M Tris buffer (pH 9.7) and was then caused to react with 0.25% azomethine H in aqueous 2% ascorbic acid for absorbance measurement at 420 nm with a two-fold online dilution. The calibration graph was rectilinear from 0.05 to 0.8 M H3BO3. The Cl- concentration. (1.7M) was determined in one of two other set-ups in a reagent stream of aqueous 15% methanol containing 2.4% HNO3, 75 mM Fe(NO3)3 and 2 mM Hg(SCN)2. The absorbance of the Fe(SCN)2+ complex formed after Cl- - Hg(SCN)2reaction, was measured at 480 nm. The methods were applied to the determination of Ni(II), Fe(II), H3BO3 and Cl- in electroplating solutions.
Iron(2+) Nickel(II) Chloride Boric acid Industrial Spectrophotometry

"Online Dilution, Steady-state Concentrations For Inductively Coupled Plasma Spectrometry Achieved By Tandem Injection And Merging-stream Flow Injection"
Analyst 1989 Volume 114, Issue 10 Pages 1259-1265
Yecheskel Israel, Alexandra L&aacute;sztity and Ramon M. Barnes

Abstract: The merging-stream technique was successfully applied in online dilution for ICP spectrometry. The precision achieved was almost the same as that for direct nebulization of a pre-diluted sample. The technique allows dilution over a range form ~7 to 900 times. Adequate accuracy was demonstrated for ICP-AES with dilutions of 200-fold, and ICP-MS of 900-fold. The online dilution methods described should be applicable to other detection techniques.
Mass spectrometry Spectrophotometry

"Determination Of Selenium In Blood Plasma And Serum By Flow Injection Hydride Generation Atomic Absorption Spectrometry"
Analyst 1990 Volume 115, Issue 3 Pages 275-278
Kieran McLaughlin, Darioush Dadgar, Malcolm R. Smyth and Dorothy McMaster

Abstract: A flow injection hydride generation atomic absorption spectrometric (AAS) method has been used to determine the selenium concentrations of human serum and plasma samples following digestion with nitric, sulfuric and perchloric acids. In the hydride generation process, reduction was carried out by sodium tetrahydroborate to produce a hydride that was atomized in a flame-heated atomisation cell. The method had a detection limit of 1.2 ng mL-1 and a sensitivity of 2.1 ng mL-1. Within-run precisions of 5.8% at 20 ng mL-1 and 4.5% at 80 ng mL-1, and between-run precisions of 4.8% at 69 ng mL-1 and 3.4% at 80 ng mL-1 were obtained. An inter-laboratory comparison study with a graphite furnace AAS method was carried out and the results showed excellent agreement. The flow injection method of sample introduction allowed the use of a sample volume of 330 µL with an injection rate of 90 injections per hour. Plasma or serum (2 ml) was digested at 140°C for 20 min (temp. raised to 140°C over 20 min) with 5 mL of 16 M HNO3 and cooled; 2.5 mL of 18 M H2SO4 and 1 mL of 11.6 M HClO4 were added and the temperature was increased to 140°C (held for 15 min), then to 205°C over 15 min (held until white fumes appeared). The residue was cooled, then heated at 95°C for 30 min with 5 mL of 5 M HCl. After cooling and dilution to 25 mL with water, a 330 µL portion was injected into the flow injection hydride generator with 1% (w/v) NaBH4 (3.9 mL min-1) - 1 M HCl (5.4 mL min-1). The H2Se produced was carried by the Ar stream to the heated silica cell of the AAS instrument and atomized at 900°C. Absorbance was measured at 196 nm. The detection limit of Se was 1.2 ng mL-1; sensitivity was 2.1 ng mL-1. Within- and between-run precisions were 4.5 and 3.4%, respectively, at 80 ng mL-1 of Se. Recoveries were 95 to 109%. Results from an inter-laboratory comparison study with graphite-furnace AAS agreed well.
Selenium Blood Plasma Blood Serum Spectrophotometry Sample preparation

"Determination Of Diphenhydramine Hydrochloride By Flow Injection With Bromophenol Blue And Turbidimetric Measurement"
Analyst 1990 Volume 115, Issue 6 Pages 855-858
J. Martinez Calatayud, A. Sanchez Sampedro and S. Navasquillo Sarrion

Abstract: Powdered tablets were mixed with water, the mixture was filtered and diluted to volume A 210 µL aliquot of the solution was injected into a carrier - reagent stream (2.69 mL min-1) of 1.19 mM bromophenol blue (pH adjusted to 1.2 with HCl). The turbidity was measured spectrophotometrically at 650 nm. The calibration graph was rectilinear for 50 to 230 ppm of diphenhydramine hydrochloride. The coefficient of variation (n = 20) was 0.3% and the injection rate was 51 samples h-1. The study of a number of diphenhydramine-dye systems was carried out in order to determine the most suitable precipitate for the turbidimetric determination of diphenhydramine using flow injection (FI). The reagent selected was Bromophenol Blue. The chemical and FI variables were optimized. The calibration graph was linear over the concentration range 50-230 p.p.m. of diphenhydramine hydrochloride. A number of interfering substances were also investigated.
Diphenhydramine Pharmaceutical Spectrophotometry Turbidimetry

"Determination Of Chlordiazepoxide By Zinc Or Cadmium Reduction In A Continuous System Followed By Atomic Absorption Spectrometric Detection"
Analyst 1990 Volume 115, Issue 7 Pages 943-949
Rosa Montero, Mercedes Gallego and Miguel Valc&aacute;rcel

Abstract: An indirect flow injection analysis - AAS method is described for determination of chlordiazepoxide (I). A portion of powdered tablets (15 to 20 mg of I) was dissolved in ethanol, with stirring, at 40°C to 50°C for 1 h. The solution was adjusted to pH 3.5 to 5.0 with 10 mM HCl and diluted to volume A portion (200 µL) was injected into a carrier stream (H2O), which was passed through a redox column (4.5 or 8.5 cm x 1.8 mm) of Cd or Zn granules (0.5 to 1.2 mm), Cu-coated Cd granules or amalgamated Zn granules. The metal in the eluate was determined by AAS, the peak being compared with that obtained by injecting a water blank (adjusted to the same pH as the sample). From 2 to 25 µg mL-1 of I could be determined, with coefficient of variation of 1.1 to 2.8%. The sampling rate was 150 h-1. Recoveries from commercial formulations were 97.3 to 102.1%.
Chlordiazepoxide Spectrophotometry

"Continuous-flow Chemiluminescence Determination Of Isoniazid By Oxidation With N-bromosuccinimide"
Analyst 1990 Volume 115, Issue 9 Pages 1229-1234
Stergios A. Halvatzis, Meropi M. Timotheou-Potamia and Antony C. Calokerinos

Abstract: Powdered tablets equivalent to 200 mg of isoniazid (I) were dissolved in water, filtered and diluted with water to give a final solution containing 0.05 to 20 µg mL-1 of I and 1.0 M-NaOH and 0.5 mM NH3. I was reacted with 15 mM N-bromosuccinimide solution in a continuous-flow chemiluminescence analyzer. (illustrated), reagent and sample flow rates were 2.5 and 3.9 mL min-1, respectively. Detection was by photomultiplication. The limit of detection was 0.024 µg mL-1 and the coefficient of variation (n = 10) for 0.2 and 1.0 µg mL-1 were 3.0 and 0.9% respectively. Recoveries of 0.2 µg mL-1 in the presence of a tenfold concentration. of fifteen additives used as excipients were 97.5 to 103.9% and for 0.2, 0.4 and 0.8 µg mL-1, were 96.0 to 104.2%. The results were compared with those obtained by the BP official method and gave a mean relative difference of 2.4%.
Isoniazid Pharmaceutical Chemiluminescence

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

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

"Online Dilution, Steady-state Concentrations By Tandem Injection And Merging Stream. Application To Inductively Coupled Plasma Atomic Emission Spectrometry Sequential Multielement Soil Analysis"
Analyst 1990 Volume 115, Issue 11 Pages 1411-1417
Yecheskel Israel and Ramon M. Barnes

Abstract: Recently developed flow injection on-line dilution methods, i.e., the merging stream and tandem injection, which yield steady-state concentrations, have been applied to the analysis of reference soil sample digests by inductively coupled plasma atomic emission spectrometry. Direct or on-line dilution determinations were applied, with dilutions ranging from 1.8 to 15 for both dilution methods. Higher dilutions are not feasible, especially when trace elements are involved. A variable speed peristaltic pump was used to limit the total flow-rate by the merging-stream dilution method to 2 mL min-1. This permitted the design of a flow module with one set of coils and a flow configuration suitable for all dilutions. Varying the dilution required only the variation of the peristaltic pump flow tube diameters. Selecting the required dilution for the tandem injection method was carried out with no manual operations and involved only pre-programming of the injection time and the injection cycle period. The results obtained exhibit comparable accuracy and precision for major and minor elements to those obtained by direct determination. By varying the dilution for the determination of trace elements, screening the optimum dilution(s) suitable for the determination of each trace element is possible.
Environmental Spectrophotometry

"Continuous-flow Chemiluminescence Determination Of Some Corticosteroids"
Analyst 1990 Volume 115, Issue 12 Pages 1553-1557
Ioanna I. Koukli and Antony C. Calokerinos

Abstract: Powdered tablets (200 mg), injection solution (2 ml) or creams (1 g) were dissolved in and diluted with 0.1 M H2SO4 for dexamethasone (I) and hydrocortisone (II) or 0.1 M H2SO4 containing 1% acetone for prednisolone (III), methylprednisolone (IV), dexamethasone (V) or betamethasone (VI). Portions of solution were analyzed in an air-segmented continuous-flow manifold by mixing the sample stream (2 mL min-1) with 0.5 mM ammonium Ce(IV) sulfate in 0.1 M H2SO4 and with aqueous 0.01 M Na2SO3 (both at 0.8 mL min-1) and the resulting chemiluminescence was measured. Calibration graphs were rectilinear from 0.1 to 1 µg mL-1 of I, II, III and IV, and from 0.5 to 5 µg mL-1 of V and VI with detection limits of 0.02 to 0.3 µg mL-1. The coefficient of variation were 1.3 to 4.9% and 1.6 to 6.2% for I and II, respectively. There was no interference from excipients. The sampling rate was 40 h-1. Results agreed well with those of an official method.
Corticosteroids Pharmaceutical Chemiluminescence

"Automated Spectrophotometric Determination Of Titanium(IV) In Water And Brines By Flow Injection Based On Its Reaction With Hydrogen Peroxide"
Analyst 1990 Volume 115, Issue 3 Pages 315-318
M. Mu&ntilde;oz, J. Alonso, J. Bartrol&iacute; and M. Valiente

Abstract: A flow injection system is described (with diagram). Water (13 µL) in H2SO4 was injected into a 0.7 M H2SO4 carrier stream (2.2 mL min-1) and diluted in a coil (50 cm x 0.7 mm) with water (2.2 mL min-1). The stream was then mixed in a coil (1 m x 0.7 mm) with 3% (w/v) H2O2 in 0.7 M H2SO4 (2.2 mL min-1) and the absorbance was measured at 410 nm. Calibration graphs of Ti in the sample were rectilinear up to 1000 ppm at a sampling rate of 240 hmin1. Detection limit was 9 ppm, and the coefficient of variation was 0.6%. Interference from Fe, V and Mo can be avoided by selective precipitation during sample pre-treatment. A system is also described for the determination of low Ti concentration. in brine using 3.3 M Mg(NO3)2 - 1 M HCl as carrier; the calibration graph was rectilinear up to 30 ppm, coefficient of variation were 0.7% and the detection limit was 0.3 ppm.
Titanium(IV) Water Environmental Spectrophotometry

"Extending Online-dilution Steady-state Concentration Range By Modification Of The Merging-stream And Tandem-injection Continuous-flow Methods"
Analyst 1991 Volume 116, Issue 5 Pages 489-495
Yecheskel Israel and Ramon M. Barnes

Abstract: Flow injection manifolds are described (with diagrams) for tandem-injection and hydrodynamic tandem-injection systems which have been modified by the introduction of new flow configurations. A flexible flow approach for online dilution with totally variable speed flow allows the operation of an online dilution system at a constant over all flow-rate over all achievable dilutions. This improves the precision of the steady-state concentration. section allowing the choice of a single efficient coil or coil assembly. Stream flow splitting of the diluted sample by the merging stream or tandem injection approach followed by re-emerging the split stream with the diluent are the most effective means of extending the dilution range. Each of the dilution techniques can be combined with each other to provide specific steady-state concentration. online dilution.

"Novel Single-standard Calibration And Dilution Method Performed By The Sequential Injection Technique"
Analyst 1992 Volume 117, Issue 12 Pages 1839-1844
Alan Baron, Miguel Guzman, Jaromir Ruzicka and Gary D. Christian

Abstract: The sequential injection technique is used to generate rapidly a series of exactly diluted aliquots from a single standard. It can be used to produce a calibration set (which is able to detect a non-linear response) or to dilute samples to the appropriate analytical concentration. range. Its application to analysis of glucose using glucose oxidase by both sensor-injection analysis and multi-zone stopped-flow analysis is described. A novel single standard calibration and dilution method utilizing the sequential injection analysis (SIA) technique is described. The SIA manifold employs a dilution conduit for storing a concentration. gradient of an injected analyte, which provides for a variable calibration and dilution scheme suitable for both single and multizone analyzes by taking selected aliquots from the gradient. This paper describes the principles of the method, the experimental characterization of the SIA manifold with bromothymol blue dye using a spectrophotometric detector and the application of the method to glucose determination using glucose oxidase by sensor injection analysis and by multizone stopped-flow anal.
Glucose Enzyme, glucose oxidase Sensor

"A Variable Dispersion Flow Injection Manifold For Calibration And Sample Dilution In Flame Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1986 Volume 1, Issue 4 Pages 273-276
Julian F. Tyson, James R. Mariara and John M. H. Appleton

Abstract: The manifold comprised six tubes of different dimensions (6 cm x 0.7 mm, and 18, 26, 60, 131 and 229 cm x 1.1 mm) in parallel, with a six-way switching valve at each common end. These tubes gave measured dilution factors (dispersion coefficient) of 5.93, 8.67, 10.35, 14.87, 25.99 and 38.84, respectively, which, when applied to the concentration. (5 ppm) of standard Mg solution (12.5 µL of which was passed down each tube), permitted a calibration graph to be established. When solution containing 6, 12.5, 12.5 and 35 ppm of Mg were passed down the tubes that gave dilution factors of 14.87, 14.87, 25.99 and 38.84, respectively, the concentration. found from the calibration graph were 6.1, 12.5, 12.4 and 33.8 ppm. Calibration with solution containing Ca, Cr or Ni gave 98 to 102% recovery of 75, 180 and 180 ppm of the respective metals from at least one of the tubes. The dilution factors were independent of concentration, but their uncertainty did render the over-all precision inferior to that for conventional calibration.
Chromium Copper Magnesium Nickel Spectrophotometry

"Flow Manifold For Automated Online Dilution Of Standards For Flame Atomic Absorption Spectrometry And Its Use In A Null Measurement Method"
J. Anal. At. Spectrom. 1987 Volume 2, Issue 2 Pages 217-220
Stephen R. Bysouth and Julian F. Tyson

Abstract: The cited manifold is based upon a fixed-speed pump, together with a computer-controlled switching valve and pump, so that automatic dilution is combined with maintenance of a constant-volume flow to the nebulizer for flame AAS. The computer is also used for data handling and processing. Operation in flow injection mode with manual control of the switching valve and pump has been tested with no great success. Calibration can be in the conventional manner or by a null measurement method in which a stock standard solution is diluted by a known factor to match precisely the absorbance of the sample; Cr (null measurement mode) and Mg (flow injection mode) are used as test analytes. In the null measurement method, peristaltic-pump flow pulsation gives rise to problems with accurate flow-rate measurement which remain to be solved successfully.
Chromium Magnesium Spectrophotometry

"Network Flow Injection Manifolds For Sample Dilution And Calibration In Flame Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1988 Volume 3, Issue 1 Pages 211-215
Julian F. Tyson and Stephen R. Bysouth

Abstract: An asymmetrical two-branch network permitting measurement at the maxima of and the minimum between two overlapping peaks generated from a single injection and a three-branch network permitting measurement at three such maxima and the two minima between them are described. Their performance in the dilution of off-range samples and extension of the calibration range is compared. The two-branch network was the better, being the less sensitive to flow-rate fluctuations.
Magnesium Spectrophotometry

"Online Isotope-Dilution And Sample Dilution By Flow Injection And Inductively Coupled Plasma Mass-Spectrometry"
J. Anal. At. Spectrom. 1990 Volume 5, Issue 2 Pages 125-133
Mikl&oacute;s Viczi&aacute;n, Alexandra L&aacute;sztity, Xioaru Wang and Ramon M. Barnes

Abstract: The applicability of a flow injection system for online isotope or sample dilution, achieved by merging the sample solution with the tracer solution or a diluent, respectively, is demonstrated by use of both multiple injections and a steady-stream flow configuration. The adequacy of mixing of the two solution and the effect of the sample-to-tracer ratio on precision and accuracy were studied. Advantages of the proposed technique include the use of the same solution for measurement of concentration. and isotope ratio, and reduced sample preparation times for inorganic aqueous solution Disadvantages include unwanted further sample dilution, the need to measure the isotope abundances of the diluted tracer solution, and the fact that correction for analyte losses during sample preparation is not possible.
Mass spectrometry

"Flow Injection Flame Atomic-spectrometric Determination Of Aluminum, Iron, Calcium, Magnesium, Sodium And Potassium In Ceramic Material By Online Dilution In A Stirred Chamber"
J. Anal. At. Spectrom. 1991 Volume 6, Issue 3 Pages 233-238
Vincente Carbonell, Angel Sanz, Amparo Salvador and Miguel de la Guardia

Abstract: A versatile manifold is proposed which permits the online dilution of samples previously fused with metal carbonates. The manifold was used in the determination of Al, Fe, Ca, Mg, Na and K in ceramics, e.g., clay, kaolin, quartz, felspar, stoneware and porcelain. The effect of the flow injection parameters on the characteristics of the flame ASS determination was studied and results from analysis of real samples compared with results from batch analyzes.
Aluminum Calcium Iron Magnesium Potassium Sodium Ceramic Spectrophotometry

"Continuous-flow Dilution For Flame Atomic Absorption Spectrometry Using A Variable-volume Dilution Chamber And Peak Area Measurement"
J. Anal. At. Spectrom. 1991 Volume 6, Issue 4 Pages 307-311
Ernest Beinrohr, Pavol Cs&eacute;mi and Julian F. Tyson

Abstract: A simple, flow injection based procedure for extending the dynamic range of flame AAS was studied. The theoretical and experimental basis of continuous-flow dilution in a variable volume mixing chamber and calibration through peak area measurement is described. The latter enables simple quantification of the contents of samples with a wide range of analyte concentration. The linear dynamic range of flame AAS can be increased by 2 to 3 orders of magnitude. The calibration graph was rectilinear from 0.1 µg mL-1 to 9 mg mL-1 of Cu.
Copper Spectrophotometry

"Multidetection In Unsegmented Flow Systems With A Single Detector"
Anal. Chem. 1985 Volume 57, Issue 9 Pages 1803-1809
Angel Rios, M. D. Luque de Castro, and Miguel Valcarcel

Abstract: A single-beam commercial spectrophotometer is incorporated in a closed flow system, in which entrapment of an increment of sample allows its repetitive passage through the detector (thus providing transient signals) until it is completely dispersed into the carrier. The number of peaks obtained per sample is a function of its volume and flow rate and the reactor length. The envelope of the maximum (or minimum) of these peaks defines a kinetic curve that allows the application of conventional kinetic methods of determination and calculations of the partial reaction orders and rate constants. The application of dilution or amplification methods for concentrated or dilute samples, respectively, is also possible. The method is applicable to systems that involve or do not involve a chemical reaction; the examples cited include the rate of dilution of bromocresol green, the reduction of Cr2O72- by ascorbic acid, and the ligand-displacement reaction between 3,6-dioxaoctane-1,8-diamine-NNN'N'-tetra-acetic acid, 4-(2-pyridylazo)resorcinol and Fe(III).
Spectrophotometry

"Ion-spray Mass Spectrometry - Mass Spectrometry: Quantitation Of Tributyltin In A Sediment Reference Material For Trace Metals"
Anal. Chem. 1989 Volume 61, Issue 20 Pages 2320-2322
K. W. Michael Siu, G. J. Gardner, and S. S. Berman

Abstract: The reference material, viz, PACS-1, was sonicated with methanol - 10 M HCl (2:1) and extracted with 2,2,4-trimethylpentane, and the extract was diluted with methanolic 1 mM ammonium acetate. Alternatively, the sample was sonicated with butan-1-ol and the extract was likewise diluted. The solution were delivered to the ion-spray source by flow injection. Detection was by selected-ion monitoring of the daughter - parent pair at m/z 179/291. The result of 1.29 ppm with a standard deviation (n = 5) of 0.07 ppm was in close agreement with the certified value.
Tributyltin NRCC PACS-1 Environmental Sample preparation Mass spectrometry

"Split Zone Flow Injection Analysis. An Approach To Automated Dilutions"
Anal. Chem. 1989 Volume 61, Issue 15 Pages 1773-1778
Gregory D. Clark, Jaromir Ruzicka, and Gary D. Christian

Abstract: A simple, automated, on-line dilution system based on flow injection analysis (FIA) has been developed. The method relies on the reproducible cleavage of a dispersed sample zone, thereby attenuating the resulting peak's area and increasing its dispersion coefficient. Salient and practical features of previous dilution systems, developed by this and other groups, have been Incorporated, making this system versatile and practical. Four methods for achieving dilutions were studied. These systems were evaluated for durability, reproducibility, range of dilution, and speed. A 0.0023 M solution of bromocresol green dye was used as a test solution for the dilutions. Other factors that might affect the dilutions, such as viscosity, were studied. A method for calculating the delay time required for a given dilution factor is discussed.

"Selective Determination Of Histamine By Flow Injection Analysis"
Anal. Chem. 1990 Volume 62, Issue 18 Pages 1971-1976
James M. Hungerford, Kevin D. Walker, Marleen M. Wekell, Jack E. LaRose, and Harold R. Throm

Abstract: A flow injection analysis (FIA) method for the determination of histamine is described. Control of reaction timing allows exploitation of a transient, chemical-kinetic increase in selectivity that occurs when o-phthalaldehyde reacts with histamine. The molar fluorescence ratio (selectivity) of histamine/histidine reaches a maximum value of 800 in 32 s, precluding the need for separation of histamine from histidine, spermidine, and other potential interferences in biological samples. Online dilution prevents matrix effects and affords a linear response up to approximately 4.45 mM histamine, or 500 mg of histamine free base/100 g. Under these conditions the detection limit (3 times peak-to-peak baseline noise) is 5.5 pg (corresponding to 0.60 mg of histamine free base/100 g of sample) and throughput is 60 injections per hour. The high sensitivity and high selectivity of the method allow the rapid determination of histamine in fish with minimal sample conditioning and will find application in the determination of endogenous histamine as well, such as in blood plasma and brain tissue.
Histamine Blood Plasma Brain Marine Fluorescence

"Expansion Of Dynamic Range Of Flame Atomic Absorption Spectrometry By An Efficient Flow Injection Dilution System Based On Dispersion Of Microlitre-volume Samples"
Anal. Chem. 1993 Volume 65, Issue 13 Pages 1682-1688
Zhaolun Fang, Bernhard Welz, and Michael Sperling

Abstract: The system incorporated two computer-controlled stepper-motor-driven peristaltic pumps. One of these was used for the sample solution; by varying the pump speed or metering time, the solution (0.7-35 µL) was injected into a 100 µL loop. The other pump was used for the diluent; both pumps made use of 0.25-mm-bore tubing. The sample and diluent (carrier) were mixed in tubes (160 cm x 1.3 mm), which were either coiled or randomly knotted. The performance was tested by the dilution of 0.1% Mg2+ solution, with measurement at 285.2 nm. With a sample volume of 0.7 µL and a dilution factor of 1,330, the RSD was 1.8%. With a sampling pump speed of 10 rpm and sampling times of >2 s (volume >1.4 µL), the RSD were 0.5-0.6%. Sampling frequencies of 60-100/h were possible, even at the highest dilutions. The use of different dilution factors made it possible to vary the rectilinear working range. The method was further tested by dissolving Al reference alloy BAM-206 (1 g) in 6 M HCl (10 ml), diluting the solution to 100 mL and analyzing the solution directly with 1.4 µL samples. The Mg content found was (7.20 ± 0.12)%, compared with the certified value of 7.17%.
Magnesium Alloy Spectrophotometry

"Flow Injection Calibration Techniques"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 663-667
Julian Tyson

Abstract: A review is presented, with 28 references. Examples are described of the various manifolds and methods designed for this purpose, especially for use in conjunction with atomic spectrometry.
Spectrophotometry

"Expansion Of The Dynamic Range Of Flow Injection Analysis Systems For Complete Batch Process Monitoring"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 678-684
C. Thommen, M. Garn und M. Gisin

Abstract: Online monitoring of industrial processes requires a wide dynamic range, and methods to achieve this are discussed. Of two methods described in detail, the simpler involves combination of peak height measurement with electronic dilution or peak-width measurement, the latter being used when the concentration. is too high for peak height to be used. An example given is the determination of aromatic amines. For more precise measurements, gradient dilution can be used with time-variable zone sampling, as in the monitoring of glucose in fermentation processes.
Amines, aromatic Industrial

"Determination Of Chlorhexidine By Flow Injection Analysis"
Fresenius J. Anal. Chem. 1988 Volume 332, Issue 4 Pages 370-371
K. K. Lau

Abstract: Chlorhexidine digluconate(I) was determined by flow injection analysis with detection in a Jasco UVidec-160 UV - visible spectrometer with a 0.07 mL, 10-mm Hellma flow-through cell (system shown diagramatically). The method involved reaction with NaBrO in the presence of cetrimide, and the short sampling period afforded a high sampling rate. Detection was at 475 nm. This method is rapid, reproducible, simple to perform and suitable for routine determination.
Chlorhexidine digluconate Spectrophotometry

"Direct Determination Of Calcium, Magnesium, Sodium And Potassium In Water By Flow Injection Flame Atomic Spectroscopy, Using A Dilution Chamber"
Fresenius J. Anal. Chem. 1989 Volume 335, Issue 8 Pages 975-979
M. de la Guardia, V. Carbonell, A. Morales and A. Salvador

Abstract: The cited elements were determined in water using a dilution chamber to extend the calibration range and allow a single concentration. standard to be used for the calibration of each analyte. A double channel injector and the merging zone technique were used to add La solution to the samples (1:1) and reduce reagent consumption. Samples were analyzed by flow injection flame AAS, peak heights were measured at 422.67, 285.21, 589.00 and 766.49 nm for Ca, Mg, Na and K, respectively. Results agreed well with those obtained by a batch AAS procedure and gave better precision. Sensitivities were 0.0408, 0.046, 0.0122 and 0.20 ppm and detection limits were 2.5, 1.5, 7.0 and 0.5 ppm for Ca, Mg, Na and K, respectively. The sample throughput was ~180 samples h-1. The cited elements were determined in water using a dilution chamber to extend the calibration range and allow a single concentration. standard to be used for the calibration of each analyte. A double channel injector and the merging zone technique were used to add La solution to the samples (1:1) and reduce reagent consumption. Samples were analyzed by flow injection flame AAS, peak heights were measured at 422.67, 285.21, 589.00 and 766.49 nm for Ca, Mg, Na and K, respectively. Results agreed well with those obtained by a batch AAS procedure and gave better precision. Sensitivities were 0.0408, 0.046, 0.0122 and 0.20 ppm and detection limits were 2.5, 1.5, 7.0 and 0.5 ppm for Ca, Mg, Na and K, respectively. The sample throughput was ~180 samples h-1.
Calcium Magnesium Sodium Potassium Environmental Spectrophotometry

"Flow Injection Determination Of Boron, Copper, Molybdenum, Tungsten, And Zinc In Organic Matrices With Direct-current Plasma Optical-emission Spectrometry"
Fresenius J. Anal. Chem. 1989 Volume 335, Issue 8 Pages 893-899
M. C. Brennan and G. Svehla

Abstract: The sample was dissolved in a suitable solvent, and the solution was diluted with isobutyl methyl ketone and introduced via a 600 µL loop into a stream of anhydrous acetic acid (4.5 mL min-1) and then to the nebulizer of the spectrometer via a 25-cm silicon rubber tube (0.8 mm i.d.). The line intensities were measured at 249.773, 324.754, 379.825, 400.875 and 202.548 nm for B, Cu, Mo, W and Zn, respectively. Calibration graphs were rectilinear up to 500 ng mL-1 of B, Cu, Mo and Zn and up to 1000 ng mL-1 of W with detection limits of 21, 14, 28, 120 and 20 ng mL-1 for B, Cu, Mo, W and Zn, respectively. The throughput was 100 samples h-1. The continuous introduction of the carrier liquid into the plasma cleaned out the nebulizer and reduced memory effects.
Boron Copper Molybdenum Tungsten Zinc Spectrophotometry

"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 Urine Spectrophotometry

"Automated Dilution In Flow Injection Analysis With Double Online Dialysis. System For The Determination Of Chloride In Industrial Effluents And Plating-bath Solutions"
Fresenius J. Anal. Chem. 1991 Volume 340, Issue 7 Pages 415-418
J. F. van Staden

Abstract: A flow diagram is shown for the determination of Cl- by injection of the sample into water (carrier stream), followed by online dialysis across Technicon type C membranes in two separate stages against water, and reaction with Hg(SCN)2 - Fe(NO3)3 color reagent (prep. described) before spectrophotometry at 480 nm. No samples prep. or dilution is necessary; 100 samples can be analyzed in 1 h. The coefficient of variation (n = 15) for 8 to 60 g L-1 of Cl- was 0.8%. Results agreed with those obtained by a standard automated segmented method involving manual dilution.
Chloride Industrial Spectrophotometry

"Extending The Dynamic Range Of Flame Atomic Absorption Spectrometry: A Comparison Of Procedures For The Determination Of Several Elements In Milk And Mineral Waters Using Online Dilution"
Fresenius J. Anal. Chem. 1996 Volume 355, Issue 1 Pages 57-64
I. L&oacute;pez Garc&iacute;a, P. Vi&ntilde;as, N. Campillo and M. Hern&aacute;ndez C&oacute;rdoba

Abstract: Three previously described flow injection manifolds (Lopez Garcia et al., J. Anal. Atomic Spectrom., 1992, 7, 1291; Ibid., 1994, 9, 553; Ibid., 1994, 9, 1167) are described and evaluated for their abilities to extend the dynamic range of flame AAS. The systems were used for elemental determination in infant formulae, powdered milk and mineral water. The results obtained by using each manifold are tabulated and discussed. The continuous-flow method is shown to be a reliable alternative to dilution procedures and the systems can be automated or semi-automated.
Trace elements Mineral Baby Powder Spectrophotometry

"Online Dilution With Sequential Injection Analysis: A System For Monitoring Sulfate In Industrial Effluents"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 6 Pages 577-581
J. F. van Staden and R. E. Taljaard

Abstract: Two manifold sequential injection analysis systems were evaluated: one included a dilution step (system A) and one had a dilution coil in the manifold (system B). The components of each system are illustrated. Flow rates for both systems were 5 ml/min. Standard sulfate solutions were prepared from 1-5000 g/l. Barium chloride reagent solution was used, containing potassium hydrogen phthalate/HCl buffer of pH 2.5, filtered to 45 µm. The device sequences of the two systems are tabulated. For system A, dilution is carried out in the well defined water zone between the barium chloride reagent and the sample zone with a timing sequence from 0-15 S. In addition, 47g EDTA/ammonium chloride (40:7) and 57 mL ammonia were dissolved in 600 mL water, diluted to 1l and this buffer was introduced between samples at the start of each sequence. Calibration graphs were linear from 50-5000 mg/l sulfate for system B; RSD were n=10) for both systems. The merits of each system are discussed.
Sulfate Waste Industrial Turbidimetry

"Flow Injection Analysis Of Fluoride In Electroplating Baths With Potentiometric Detection"
Fresenius J. Anal. Chem. 1998 Volume 362, Issue 2 Pages 230-233
R. P&eacute;rez-Olmos, M. B. Etxebarria, J. L. F. C. Lima, M. C. B. S. M. Montenegro

Abstract: A high dispersion FIA system with a fluoride-selective and a double junction reference electrode in cascade arrangement was developed for the determination of F- in chromium electroplating baths. The analyzes of seven synthetic baths prepared in the laboratory and two samples provided by the industry gave results with a mean recovery value of 100.5% and a mean variation coefficient of 1.6%. These data are better than those obtained by the EDTA complexometric titration, the reference technique, with a mean recovery of 94.0% and a mean variation coefficient of 7.5%. The sampling rate for the FIA manifold was 20 samples per h.
Fluoride Chromium Electrode Potentiometry

"Efficient Flow Injection Online Dilution System For Flame Atomic Absorption Spectrometry Based On Micro-zone Penetration"
Microchem. J. 1994 Volume 50, Issue 2 Pages 145-150
Xu S. K. and Fang Z. L.

Abstract: Combination of microsampling dilution with zone penetration produced an efficient automated dilution system for flame AAS capable of direct determination of Na, K and alkaline-earth metals in samples containing several g/l of the analytes. The highest dilution factor attained was 27 000 but values of 50 000 might be possible using updated software. Sampling frequency was 45/h and RSD were better than 2%. A drawback is that readouts have to be made manually on the recordings. The system was applied to the determination of Mg in brines used in bean curd production.
Sodium Potassium Metals, alkaline earth Magnesium Environmental Spectrophotometry

"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 Urine HPLC Fluorescence

"Determination Of Tin In Biological Samples Using Gaseous Hydride Generation - Inductively Coupled Plasma Atomic Emission Spectrometry"
Anal. Biochem. 1990 Volume 190, Issue 1 Pages 71-77
Katsuhiko Yokoi, Mieko Kimura and Yoshinori Itokawa

Abstract: Liver, brain, testis or kidney was homogenized and heated with HNO3 and HClO4 in Kjeldahl flasks until white fumes appeared. Water was added with heating until the solution was clear and colorless. An aliquot of the solution was treated with trichloroacetic acid (I) and diluted with water to 0.2% in I. This solution was mixed, in a continuous-flow hydride-generation system (diagram given), with 1% I solution and then with 0.5% NaBH4 in 0.1% NaOH solution and passed through a gas - liquid separator (design presented) and the hydride, in an Ar-stream, was determined by ICP-AES at 189.989 nm. The limit of detection was 30 pg mL-1 of Sn, mean recovery was 87 to 99% and the coefficient of variation was 1.2%.
Tin Liver Brain Kidney Testis Spectrophotometry

"An Improved Zone Sampling Method For Flow Injection Analysis"
Anal. Lett. 1988 Volume 21, Issue 9 Pages 1633-1651
Toei, J.

Abstract: An improved zone sampling method where a small volume mixing device is placed before the fraction loop has been developed. In this method the samples are dispersed by the gradient chamber (device) and its dispersion profile of the injected samples is exponential. Therefore, the fraction difference caused by a lug of the fraction timing is small and consequently the optimization of system is very easy. The method was applied to the predilution of the samples in clinical flow injection analysis.
Glucose Blood Serum Spectrophotometry

"Extractable Sulfate-sulfur, Total Sulfur And Trace-element Determinations In Plant Material By Flow Injection Analysis. 2. Total Sulfur And Copper, Zinc, Manganese And Iron In Plant Material"
Anal. Lett. 1990 Volume 23, Issue 4 Pages 675-702
D. L. Heanes

Abstract: Oven-dried samples (200 to 500 mg) were digested (at 100 samples per day) with HNO3 containing HClO, NH4NO3 and CaCl2 in a Pyrex tube at 60°C to 220°C (details given). The cooled digest was diluted to 15 mL with water and a flow injection analysis (FIA) system was used for the turbidimetric determination of total S in the supernatant solution, with the use of aqueous 0.01% Brij 35 as carrier solution, aqueous 1% Na ascorbate as sample diluent, and 0.25% of Na2EDTA in 0.1 M NaOH and 11% of BaCl2.2H2O in 1% gum arabic as reagent solution (valve switch timing sequence given). The throughput rate was 120 samples h-1. Calibration graphs were rectilinear for 1 to 200 mg mL-1 of sulfate-S in 0.25 M HClO4. The detection limit was 8 mg kg-1 in plant material. In the determination of 100 mg L-1 of sulfate-S in 0.254HClO4 and the analysis of kale, lucerne hay and oat grain, the coefficient of variation was 0.7% (n = 10). The recovery of 0.2% of S in plants was 97 to 104%. There was no interference from 6% of Ca, 5% of Mg, Na or K, 2.5% of Si, or 0.5% of P or N. A procedure for the FIA of Zn, Mn, Cu and Fe with AAS detection was also described.
Sulfate Sulfur Copper Zinc Manganese Iron Vegetable Oat Lucerne Sample preparation Spectrophotometry Turbidimetry

"Direct Determination Of Potassium In Human Blood Serum By Flow Injection Flame Photometry With Automatic Dilution"
Anal. Lett. 1996 Volume 29, Issue 10 Pages 1719-1727
Ana Cl&aacute;udia de Paiva; Graciliano de Oliveira Neto; Matthieu Tubino; Nelci F. Hoehr

Abstract: Serum (100 ml) was injected into the flow system via a flow injection manifold (schematic given) and diluted fourfold with water. The flow was diluted into two parts by a splitter and mixed with water in a ratio of 1:8 with a final dilution to ~1.32 after passing through a second splitter. Readings were taken with use of a flame photometer. The sampling rate was ~60 samples/h. The sampling flow rate was 3 ml/min (other flow rates are fixed by the tube diameter and are given). Calibration was linear up to 12.5 mM K+. The experimental error was ±5%. The results compared well with those obtained by a manual photometric method.
Potassium Serum Human Spectrophotometry

"Dilution Methods In Flow Injection Analysis. Evaluation Of Different Approaches As Exemplified By The Determination Of Nitrosyl In Concentrated Sulfuric Acid"
Anal. Lett. 1998 Volume 31, Issue 13 Pages 2181-2194
Ulla V. J&oslash;rgensen; Steffen Nielsen; Elo H. Hansen

Abstract: Instigated by developing a flow injection procedure for assay of nitrosyl in concentrated H2SO4, different approaches for reliable and robust online dilution in FIA were evaluated. These comprised the application of mixing tees in conjunction with mixing coils (including knotted reactors) of different internal diameter, zone sampling, the use of a mixing chamber, micro-sampling, and sample injection by pseudo-hydrodynamic injection. The individual approaches are described in detail, their advantages and disadvantages being emphasized in regard to their practical applicability. For each approach the criteria stipulated were that the procedure should allow a dilution factor of ~100, yet without excessive zone spreading, so that it, on one hand, could effectively eliminate the pronounced Schlieren effect encountered when mixing concentrated H2SO4 with an aqueous diluent, and, however, would permit the sample material to be appropriately conditioned for the ensuing chemical derivatization procedure. This most reliably could be effected by a combination of pseudo-hydrodynamic injection comprising a mixing point and the use of mixing tees in conjunction with knotted reactors of relatively large internal diameter (1.5 mm). The optimized FI-manifold was used with the Griess method for the spectrophotometric assay of nitrosyl (nitrite) in standards prepared in the matrix of concentrated H2SO4 (detection limit 0.16 mg/L NO+-N (3s)) and in practical WSA-samples.
Nitrosyl Concentrated Spectrophotometry

"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.
Blood Plasma Urine HPLC

"Automated Flow Injection Technique For Use In Dissolution Studies Of Sustained-release Formulations: Application To Iron(II) Formulations"
J. Pharm. Biomed. Anal. 1994 Volume 12, Issue 5 Pages 635-641
Constantinos A. Georgioua, Georgia N. Valsamib, Panayotis E. Macherasb and Michael A. Koupparisa,*

Abstract: Formulations were dissolved in 0.1 M HCl (procedure described), screened and 100 µL aliquots injected into the 0.1 M HCl carrier (0.66 ml/min) and mixed with 0.1% ferrozine, [3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine monosodium salt] containing ascorbic acid (anti-oxidant) in 0.5 M acetate buffer of pH 3.7, (2.62 ml/min) and the mixture passed through a reaction coil (100 cm). The Fe(II) complex (ε = 28 000) was mixed with further acetate buffer (3.96 ml/min) in a second coil (100 cm) and absorbance measured at 562 nm. A computer program was used to optimise the system and chemical parameters with respect to throughput and sensitivity. The calibration graph was linear for 1-130 ppm of Fe(II). Two calibration graphs were constructed: absorbance at maximum peak height (1-70 ppm); and from absorbance at the descending part of the FIA peak (2-130 ppm). RSD was 3% (n = 3). Recoveries from commercial formulations ranged from 99.2 to 103.2%. The application of flow injection analysis (FIA) to automated dissolution studies of sustained-release formulations is described. The long-term stability of the dissolution-FIA analyzer. was checked during unattended operation for 42 h. The construction of multiple calibration curves with the so-called electronic dilution FIA procedure was used to extend the linear range of the determination. The computer-controlled FIA system and the principles of associated software are described and applied to dissolution studies of sustained-release formulations of iron(II) using its sensitive reaction with the color reagent, ferrozine. The extended linear range of the determination is 1-130 ppm iron(II) and the precision (RSD) better than 3% (n = 3).
Iron(2+) Pharmaceutical Spectrophotometry

"Peristaltic Pumps - Fourier Transforms: A Coupling Of Interest In Continuous-flow Flame Atomic Absorption Spectrometry"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1761-1768
I. L&oacute;pez-Garc&iacute;a, M. S&aacute;nchez-Merlos, P. Vi&ntilde;as and M. Hern&aacute;ndez-C&oacute;rdoba*

Abstract: The modulation imposed by the peristaltic pulses is Fourier-transformed into a frequency spectrum; the amplitude observable at the known pulse frequency can then be distinguished from noise signals. The module of the signal at a frequency of nomega/60 can be used as the analytical signal to lower the limit of determination by a factor of 5-6 with respect to that obtainable by aspiration. Concentrations that are too high to be measured with direct aspiration can be measured by including an auxiliary channel in the manifold to compensate for the difference between the pumping rate and the nebulizer uptake rate and using the amplitude as the analytical signal. Only a single standard solution analyzed under different conditions is required for calibration.
Spectrophotometry

"Extension Of The Dynamic-range Of Flame Atomic Absorption Spectrometry Using Flow Injection Analysis With Variable-volume Dilution Chambers"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1747-1752
H. El Azouzi, M. Y. P&eacute;rez-Jord&aacute;n, A. Salvador and M. de la Guardia*

Abstract: A simple and inexpensive procedure is proposed for the extension of the dynamic range of flame atomic absorption spectrometry measurements using online dilution. The proposed methodology is based on the use of a manifold with two coupled dilution chambers and a zone injection system. The samples are pre-diluted in a closed system which includes a variable-volume mixing chamber (10-120 ml) and two injection valves. The samples are injected through one of these valves, and the other is employed to take 100 µl of pre-diluted samples which are then passed through a new dilution chamber (volume 1-10 ml) and aspirated by the nebulizer of the instrument. A third injection valve mounted in the last part of the manifold is used for the direct injection of diluted standard solutions. Various dilution factors are obtained, ranging from 2 to 130 000 times, thus extending the analytical range of copper determination to more than 100 000 mg L-1. 29 References Two manifolds are illustrated; each incorporates a peristaltic pump that not only operates the main channel, but also provides a closed-flow pre-dilution system. The loop of an injection valve passes the diluted sample solution to a further dilution chamber (fixed-volume in one manifold and variable-volume in the other) and thence to the flame, and a further valve is provided for the direct injection of standard solutions. Dilution factors of 2-130 000 are obtainable, so that Cu can be determined at 100 g/l.
Copper Spectrophotometry

"Determination Of The Sulfate Ion Concentration In Rain Water By Flow Injection Analysis Incorporated With A Barium Chloranilate Reaction Column"
Anal. Sci. 1990 Volume 6, Issue 5 Pages 711-714
K. YAKATA, F. SAGARA, I. YOSHIDA and K. UENO

Abstract: Rain water, diluted 1:1 with ethanol, was injected into a carrier solution of aqueous 0.5% NH4Cl - ethanol (1:1; 1.9 mL min-1) and passed through a cation-exchange column (5 cm x 4.6 mm) of Muromac 50W-X 4 (100 to 200 mesh; NH4+ form) and a reaction column (same dimensions) of Ba chloranilate powder (120 mesh). The absorbance of the eluate was monitored at 530 nm. The calibration graph was rectilinear for 4 to 100 ppm of SO42-. Sample throughput was 1 min-1. The results agreed well with those obtained by the standard manual method.
Sulfate Rain Ion exchange

"High Performance Liquid Chromatographic Determination Of Acidic Catecholamine Metabolites In Human Urine Using Post-column Fluorescence Derivatization With Dl-1,2-diphenylethylenediamine"
Anal. Sci. 1990 Volume 6, Issue 5 Pages 677-682
H.-K. JEON, H. NOHTA and Y. OHKURA

Abstract: Urine was diluted 5-fold with water, ultra-filtrated, and 3,4-dihydroxymethoxymandelic acid, 4-hydroxy-3-methoxy- and 3,4-dihydroxy-phenylacetic acid and 4-hydroxy-3-methoxymandelic acid were determined by HPLC on a column (25 cm x 4.6 mm) of TSK gel DEAE-2SW anion-exchange gel (5 µm) with 25 mM NaH2PO4 (pH 3.0) - 70 µM-Na2EDTA containing 30% of acetonitrile as mobile phase (1 mL min-1) and electrochemical detection at 0.5 V vs. Ag - AgCl. The eluate was mixed with 40 mM dl-1,2-diphenylethylenediamine in propan-2-ol and 50 mM Na methoxide in propan-2-ol (0.4 mL min-1), the mixture was passed through a reaction coil (10 m x 0.5 mm) at 110°C. After cooling the fluorescence was monitored at 515 nm (excitation at 420 nm). The detection limits were 15 to 20 fmol. The method was 20-times more sensitive to 3,4-dihydroxymandelic acid than methods using meso-1,2-diphenylethylenediamine and did not require complicated sample cleanup.
Catecholamines Urine HPLC Fluorescence

"Flow Injection Technique For Determination Of Thallium, Lead And Bismuth In Nickel-base Alloys By Inductively Coupled Plasma Mass Spectrometry"
Anal. Sci. 1990 Volume 6, Issue 2 Pages 191-194
T. MOCHIZUKI, A. SAKASHITA, H. IWATA, Y. ISHIBASHI and N. GUNJI

Abstract: Nickel-based alloy (0.25 g) was dissolved in 10 mL of HCl - HNO3 (6:1). The solution was evaporated to dryness and evaporation was repeated with 7 M HNO3 (5 ml). The residue was dissolved in 7 M HNO3 (5 ml) and 2.3 M HF solution (2 ml) and the solution was diluted to 50 mL with water. A portion of this solution (240 µL) was injected into a stream of 0.7 M HNO3 - 0.09 M HF (0.6 mL min-1) and passed to the ICP-MS instrument (operating conditions described). Detection limits for Tl, Pb and Bi were 0.001, 0.04 and 0.007 ppm, respectively. Results agreed with certified values.
Thallium Lead Bismuth Alloy NIST 897 NIST 898 NIST 899 Mass spectrometry

"Online Sample And Standard Manipulation For Flame Atomic Absorption Spectrometry"
Anal. Proc. 1986 Volume 23, Issue 12 Pages 412-415
Stephen R. Bysouth, Julian F. Tyson

Abstract: Many analytical chemistry instruments require some form of calibration. Flame atomic absorption instruments, in particular, do not give a linear response with increasing analyte concentration, owing to a variety of effects related to the nebulisation, atomisation and measurement processes. With the advent of microcomputer-linked instruments, many manufacturers have tried to overcome the problem of curved calibrations by fitting curves to the calibration data, in order to be able to interpolate between the calibration points.
Chromium Spectrophotometry

"A New Approach To Dialysis In Sequential Injection Systems: Spectrophotometric Determination Of L(+)-lactate In Wines"
Am. J. Enol. Vitic. 1997 Volume 48, Issue 4 Pages 428-432
Alberto N. Ara&uacute;jo, Jos&eacute; L.F.C. Lima, M. L&uacute;cia M.F.S. Saraiva, and Elias A.G. Zagatto

Abstract: A sequential injection analysis (SIA) system for the spectrophotometric determination of L(+)-lactate using lactate oxidase/peroxidase was developed and applied to wine analysis. It incorporates a dialysis unit between the pump and the selecting valve to provide online dilution and interference minimization of the sample matrix. A volume of 100 µL of carrier solution trapped in one channel of the dialysis unit, acts as donor and acceptor solution. With an assay cycle of 262 seconds, the system allows a sample throughput of 14 samples per hour and yields precise results (rsd < 2%). Peroxidase (0.0512 IU) and 0.0384 IU of lactate oxidase promote the conversion of L(+)-lactate in 160 µL of sample, allowing its determination within the 0.25 to 2.5 g/L range. A detection limit of 0.074 g/L was calculated. Results are in good agreement with those obtained with the conventional method (Boehringer UV-Kit).
l-Lactate Wine Spectrophotometry

"Direct Determination Of Calcium And Magnesium In Serum Using Flow Injection Analysis And Atomic Absorption Spectroscopy"
Ann. Clin. Biochem. 1984 Volume 21, Issue 1 Pages 51-56
Rocks BF, Sherwood RA, Riley C.

Abstract: The use of flow injection analysis for the direct determination of calcium and magnesium in blood serum and plasma is described. An inexpensive rotary valve is used to inject the serum sample (4 µL) into a flowing non-segmented stream of reagent which carries the sample slug through a long narrow-bore coil--where it gradually disperses--and into the nebuliser of an atomic absorption spectrometer. This on-stream sample dilution removes the need for predilution of the sample. The resulting absorbance signals are recorded as peaks less than 40 seconds after sample injection. Analytical recoveries and precision are good for both elements and the results by flow injection analysis compare well with established routine methods. In the system described, for use with serum or plasma, a rotary valve was used to inject a 4 µL sample into a flowing non-segmented reagent stream, which carried the sample 'slug' through a long narrow-bore coil, in which it gradually dispersed, into the nebulizer of the spectrometer. This method of on-stream dilution overcame the need for pre-dilution of the sample, and the resulting absorbance peaks were recorded <40 s after sample injection. Analytical recovery and precision were as good as or better than those of other methods, and the results correlated well with those obtained by using manual dilution.
Calcium Magnesium Blood Plasma Blood Serum Clinical analysis Spectrophotometry

"Arsenic, Selenium And Mercury In Mineral And Curative Waters"
Brauwelt 1990 Volume 130, Issue 37 Pages 1588-1591
Meier, B.;Dietschmann, U.;Gigl, C.;Seberich, M.;Postel, W.

Abstract: The three elements were determined by AAS following hydride reduction in a flow injection system. For the determination of As, sample was mixed with HCl and KI solution (5% KI and 5% ascorbic acid), injected into a carrier of 2% HCl and reduced with NaBH4 in NaOH. The same carrier and reagent were used for the determination of Se, reduced by heating (90°C, 20 min) the sample with HCl (12 min) and diluting with water. Organic forms of Hg were converted to ionic forms by shaking the sample with HNO3, KMnO4 and water. The sample was injected into a carrier of KNO3 and reduced with NaBH4 in NaOH. The metallic Hg formed was amalgamated with Au or Pt gauze and was released into a stream of Ar by heating (600°C) for AAS analysis. The detection limits were 0.3, 0.6 and 0.1 µg L-1 for As, Se and Hg, respectively. The coefficient of variation (n = 20) were 2.9% (As and Se) and 5.2% (Hg). Results are discussed for the analysis of 44 mineral waters and six curative waters.
Selenium Mercury Arsenic Mineral Curative Spectrophotometry Spectrophotometry

"Comparison Of The Limits Of Detection Obtained By Means Of A H.f. Plasma (ICP) Used As A Source Of Photons Or Ions In Elementary Analysis"
Chimia 1990 Volume 44, Issue 4 Pages 93-96
Poussel, Emmanuelle; Michel Mermet, Jean

Abstract: A discussion is presented of the fundamental principles, including instrumental design, which determine the limits of detection in ICP-AES and ICP-MS. The better sensitivity of ICP-MS for analysis of solution is less of an advantage in analysis of solids because of the greater dilution factor that may be required. Alternative methods of sample introduction, including flow injection, electrothermal vaporization and laser ablation, are considered. These developments and those in instrumental design will make ICP-MS a very powerful method for ultratrace analysis.
Spectrophotometry Mass spectrometry

"Simultaneous Determination Of Calcium And Potassium, Magnesium And Sodium, And Potassium And Sodium In Wine Using Flow Injection Analysis Manifolds With A Dialysis Unit"
Connaiss. Vigne Vin 1990 Volume 24, Issue 4 Pages 167-176
J.L.F.C. LIMA, A.O.S.S. RANG EL, M.M. ROQUE DA SILVA

Abstract: A dialysis unit was incorporated into a flow injection analyzer. manifold in order to achieve the large dilutions required for analysis and to halve the stream to allow simultaneous determination of two cations. Schematic diagrams are presented to give full details of reagents, flow rates and mixing times for the determination of Mg and Ca, using AAS detection, and K and Na using flame photometric detection. Calibration graphs were rectilinear from 5 to 300, 9 to 1500, 7 to 120 and 3 to 180 mg L-1 for Na, K, Mg and Ca, respectively. The coefficient of variation (n = 10) were 1% for Ca and Mg and 6% for Na and K. Sample throughput was 120 h-1. Results are presented for the analysis of a number of wines and agree well with those obtained by standard procedures.
Potassium Calcium Magnesium Sodium Wine Spectrophotometry

"Online Dilution Of Highly Concentrated FIA Samples"
Fenxi Ceshi Xuebao 1998 Volume 17, Issue 1 Pages 73-75
Chen Zhenning, Zhou Ding

Abstract: A new dispersion/zone sampling technique is described for the online dilution of highly concentrated samples in flow injection analysis The various factors affecting dispersion were examined, such as the length and diameter of the dispersion tubing, the time interval between dispersion and zone sampling, etc. The precision of this method is better than the zone sampling method. The relative standard deviation is <3%.

"Stopped-flow Catalytic Spectrophotometric Determination Of Trace Manganese"
Fenxi Huaxue 1990 Volume 18, Issue 11 Pages 1041-1043
Li, K.;Ren, Y.

Abstract: A flow injection analysis method is proposed (diagram given). Natural water, containing 180 ng of Mn, is mixed with 2 mL of 9 mM nitrilotriacetic acid solution (pH 3.8; I), 5 mL of 0.2 M Na acetate - acetic acid buffer (pH 3.8) and diluted with water to 25 mL. Three reagent streams of viz, 20 µM-Malachite green (C.I. Basic Green 4), 10 mM KIO4 and 10 mM I solution in buffer solution (pH 3.8), are pumped (2 mL min-1) into a reactor for 1 to 2 min with a stopped-flow time of 10 min. The mixture is mixed with a carrier stream of test solution (2 mL min-1) at 52°C in a 2-m coil with detection at 615 nm. The calibration graph was rectilinear for up to 7.2 ng mL-1 of Mn2+ and the detection limit was 0.07 ng mL-1. The coefficient of variation was 3.9%.
Manganese Environmental Spectrophotometry

"Enhancement Effect Of Organic Reagent And Carrier Stream On Sensitivity Of Chromium In Flow Injection Atomic Absorption Spectrometry"
Fenxi Huaxue 1990 Volume 18, Issue 10 Pages 955-957
Wei, J.H.;Lin, F.;Wang, X.S.

Abstract: Steel (0.1 g) was dissolved in aqua regia and diluted with water and then with ethanol. A 300 µL aliquot of the solution was injected into the flow injection analyzer. and reacted with a reagent stream of 10% Na dodecyl sulfate solution (12.5 mL min-1) for analysis by AAS. The calibration graph was rectilinear up to 1.5 µg mL-1 of Cr; the detection limit was 62 ng mL-1. To overcome matrix interference, Fe3+ ( 0.2 mg mL-1) was added to the standard solution The method was 7.6-fold more sensitive than methods which do not employ the organic solvent and reagent; interference from Fe3+ and other ions was also eliminated. The coefficient of variation was 1.4% and the sampling rate was 100 h-1.
Chromium Spectrophotometry

"Studies On Flow Injection Analysis Automatic Dilution Techniques And Their Applications"
Fenxi Shiyanshi 1991 Volume 10, Issue 3 Pages 56-58
Lin, S.;Lu, L.;Li, Y.

Abstract: Three types of automatic dilution techniques, viz., small-volume injection sampling, sequental-injection zone sampling and sample splitting, were investigated, with regard to simplicity, flexibilty, dilution factors and precision. Dilution factors were from 50 (for small-volume injection sampling) to 1000 (for sample splitting). The techniques were highly efficient with excellent precision over a wide range of dilution. The sample-splitting method was applied to ores and electroplating solution; coefficient of variation were 0.3%.
Geological Industrial

"Enzymic Determination Of Glucose, Sucrose And Maltose In Food Samples By Flow Injection Analysis"
Food Chem. 1990 Volume 35, Issue 2 Pages 109-116
S. M. Tzouwara-Karayanni* and S. R. Crouch

Abstract: Wheat flour (1 g) was mixed with ethanol (1 ml) and the mixture was diluted to 10 mL with water. After centrifugation (20 min at 1000 rpm), the supernatant solution was analyzed. Soft drinks were degassed, and honey was diluted (1:10) before analysis. Wine needed no pre-treatment. For determination of glucose (I), sample solution (0.1 to 1 ml) were diluted to 10 mL with 0.05 M phosphate buffer and then passed through a single bead string reactor containing glucose oxidase. The eluate from this reactor was mixed with a reagent stream containing peroxidase (0.8 mg mL-1), 1 mM 4-aminoantipyrine and 1 mM 3,5-dichloro-2-hydroxyphenylsulfonic acid in 0.05 M phosphate buffer and passed through a plain single bead string reactor. The absorbance was measured at 510 nm. For determination of sucrose (II), the samples were treated with invertase; for the determination of maltose (III) samples were treated with maltase. Calibration graphs were rectilinear from 0.01 to 0.08% of I and III and from 0.01 to 0.12% of II. Results compared well with those by the AOAC method. Recoveries were quantitative.
Glucose Sucrose Maltose Wine Soft drink Spectrophotometry

"Development Of A Robust Online Monitoring And Control System For Nutrients And Metabolites In Fermentations. 2. System Calibration"
Genet. Eng. Biotechnol. 1995 Volume 15, Issue 4 Pages 225-233
Keay, P.J.;Wang, Y.;Seddon, C.;Seddon, T.

Abstract: Calibration of the gas-driven flow injection system described in Part 1 is described. The dispersion coefficient for the system was measured and the performance (reproducibility) of the system was tested using phosphate determination. The possibility of online flow dilution confers wide flexibility and can make physical dilution unnecessary. The spectrophotometric determination of glucose and lactate by enzymatic methods and of ammonia via indophenol formation are described. The stability of these assays was measured; graphs of absorbance vs. concentration are included for each analyte.
Glucose Lactate Ammonia Fermentation broth Spectrophotometry

"Evaluation Of Three FIA Standard-addition Calibration Methods For ICP Spectroscopy"
Guangpuxue Yu Guangpu Fenxi 1990 Volume 10, Issue 2 Pages 49-53
Fan, S.;Fang, Z.L.

Abstract: Soil (0.2 to 0.5 g) is mixed with a few drops of water, 5 mL of HNO3 - HClO4 (3:1) and 3 mL of HF and then evaporated at 180°C to ~1 ml; 5 mL of 10% HCl is added to the residue which is then boiled. After cooling, the mixture is diluted with 10% HCl to 50 mL. Three methods used for analysis of the solution are those of Araujo (Anal. Chim. Acta, 1985, 17, 337), Tyson (Anal. Chim. Acta, 1983, 145, 159) and Fang (Anal. Chem., 1985, 57, 1457); procedures and diagrams of FIA systems are presented. Precision and recovery of these methods are compared, and their capabilities to compensating various matrix effects are detailed.
Environmental Sample preparation Spectrophotometry

"Application Of 4-aminohippuric Acid Chlorophosphonazo In Determination Of Palladium(II) By Spectrophotometry And Flow Injection Analysis"
Huaxue Shiji 1990 Volume 12, Issue 1 Pages 12-14
Chen Xingguo Xu Yanjun Liu Mancang Hu Zhide

Abstract: Ore (0.2 g) is dissolved in 10 mL of aqua regia, evaporated to near dryness and further evaporated to near dryness with 2 mL of HCl prior to dilution with 10% HCl to 10 mL. For direct spectrophotometric determination, an aliquot of the solution is treated with 5 mL of 12N-H2SO4, 0.5 mL of 1 mM cited compound (N- 4-[7-(4-chloro-2-phosphophenylazo)-1,8-dihydroxy-3,6-disulfo-2-naphthylazo]benzoyl glycine; I) followed by heating in a boiling-water bath for 5 min, dilution to volume and measurement of absorbance at 631 nm (ε = 37,000) vs. a reagent blank. Beer's law is obeyed for 3 to 20 µg of Pd(II) in 25 mL of final solution For flow injection analysis, 100 µL of the solution is applied to the apparatus (diagram given) and flows to the reactor coil (at 90°C) with a stream of 2% H2SO4 to mix with 80 µM-I and then 5N-H2SO4 before measurement of absorbance at 631 nm; the sampling rate is 60 samples h-1. The calibration graph is rectilinear for 0.25 to 1.25 µg of Pd in 1 mL of solution The detection limit is 0.15 µg mL-1 and the coefficient of variation is 1% for 1 µg mL-1 of Pd. Interferences of 9 foreign ions in both methods have been studied.
Palladium(II) Geological Sample preparation Spectrophotometry

"Recent Development In Flow Injection Analysis"
Huaxue Tongbao 1984 Volume 47, Issue 8 Pages 22-24
Xu, S.K.;Fang, Z.L.

Abstract: A review is presented of recent sampling techniques, including flow-dynamics injection and standard-addition techniques for AAS and ICP-AES Step-wise techniques are also described, as applied to dilution, correction, titration, incremental sampling, stop - flow and fast-response determination, and scanning. (19 references).
Spectrophotometry Spectrophotometry

"A Modified FIA System For The Determination Of High Levels Of Quickly Reacting Aluminum In Aqueous Solutions"
Int. J. Environ. Anal. Chem. 1996 Volume 62, Issue 2 Pages 115-128
D. Berggren; A. Spar&eacute;n

Abstract: We have modified Clarke et al.'s (1992) flow injection system for determining 'quickly reacting Al' (Alqr) in natural waters, to make it applicable also to solutions having high (>1 mM) aluminium concentrations. By decreasing the flow rate of the carrier stream, thus diluting the sample on-line, and using a very small injection volume (12 µL), the upper end of the linear range has been increased from 2 mg Al/l to at least 30 mg/L. Good repeatability (RSD ≈1-3%, n = 4) was obtained, both for standard solutions and for natural waters. The quantification limit was about 100 µg/L and the sample throughput ~120 injections/h. Validation with synthetic model systems (Al plus F and Al plus citrate) showed that the modified set-up gave a fractionation similar to the one of Clarke et al.'s original system. The modified set-up was also tested on soil solutions, having Al qr concentrations in the range of 0.1 to 1.5 mM. The sensitivity to iron interference was largely reduced by the modification. However, determining Alqr in samples from real rat stomachs, having both high Fe(III) and protein concentrations, caused an interference from Fe(III) at concentrations lower than for standard solutions.
Aluminum Water Spectrophotometry

"Application Of A Continuous-flow Technique For Calibration And Measurement With Ion-selective Electrodes"
Izv. Khim. 1990 Volume 23, Issue 4 Pages 534-541
Ilcheva, L.;Nwajagu, C.;Vasileva, V.;Injova, D.

Abstract: For calibration, solutions containing the appropriate ions for the corresponding ion-selective electrode were placed in a flow-through cell, containing the electrode, and diluted with a suitable solution (details given). The change in potential with time was recorded and used to construct a graph of pX (where X is the ion determined) vs. potential; this was used as the calibration graph for determination of X in the solution passed through the cell at the same rate as the diluent in the calibration; interference by accompanying ions and hence selectivity was determined analogously. Results agreed well with those obtained by conventional calibration for solid membranes. For plastic membranes, results at relatively high rates of dilution deviated from those of conventional calibration.
Electrode

"Flow Injection Determination Of Sodium, Potassium, Calcium, And Magnesium In Beer By Flame Emission And Atomic Absorption Spectrometry"
J. Agric. Food Chem. 1997 Volume 45, Issue 4 Pages 1269-1272
S&iacute;lvia M. V. Fernandes and, Ant&oacute;nio O. S. S. Rangel, and Jos&eacute; L. F. C. Lima

Abstract: The normal ranges of the four cations in beers are such that substantial dilution is required to bring samples within the linear concentration ranges. Two manifolds were designed to achieve this. In one, samples (95 µL) were injected into a water carrier stream (6 ml/min), reaching a splitting point, where about 65% of the stream was rejected. The original carrier was further diluted with water (5.4 ml/min) into which a reagent plug of La(III) solution (1% in 0.6 M HCl, 0.12 ml) was injected, at a time calculated so that the diluted sample and the modifier arrived at the confluence together. After a further mixing coil, Na(I) and K(I) were determined by flame photometry, with an air/propane flame and Ca(II) was determined by AAS. In the second manifold, samples (0.2 ml) were injected into a water carrier stream (2.5 ml/min), mixed with 0.3 M HNO3 (2.5 ml/min) and passed to a dialysis unit, where the receptor solution was a plug of the La(III) solution (0.5 ml) in a water carrier (5 ml/min) timed to arrive at the same time as the sample. The Mg(II) was determined by AAS. These methods gave results in good agreement with those by the corresponding manual methods, with a sampling rate of 120-200 samples/h and greatly reduced consumption of the expensive La(III) reagent.
Calcium Magnesium Potassium Sodium Beer Spectrophotometry Spectrophotometry

"Flow Injection Analysis Estimation Of Diffusion Coefficients Of Paucidisperse And Polydisperse Polymers Such As Polystyrene Sulfonates"
J. Appl. Poly. Sci. 1991 Volume 42, Issue 7 Pages 1969-1977
William A. Boyle, Richard F. Buchholz, John A. Neal, Joseph L. McCarthy

Abstract: Flow injection analysis, often used for determination of diffusion coefficients of nonpolymeric substances, has now been applied to the characterization of pauci- and polydisperse polymers in solution. A relative method was found useful for obtaining moderate quality evaluations of diffusion coefficients and related parameters of polymers. The width at half-height W1/2 of the trace peak is found to be proportional to the number average molecular weight n of pauci- and polydisperse polymers, allowing estimation of r and diffusion coefficients. For sodium polystyrene sulfonates at substantially infinite dilution in 1.0 g L-1 Na2SO4, a linear relation has been observed between the logarithms of the molecular weight n and the mean diffusion coefficient D in the n range of 1000-90,000 g mol-1 or the D range of 30 x 10^-7 to 2 x 10^-7 cm2 s-1.
Polystyrene, sulfonated

"Continuous-flow Vapor Generation For Inductively Coupled Argon Plasma Spectrometric Analysis. 1. Selenium"
J. AOAC Int. 1990 Volume 73, Issue 3 Pages 404-410
Tracy ML, M&ouml;ller G.

Abstract: Sample (~1.5 g of solid or ~10 mL of liquid) is wet ashed with HNO3, H2SO4 and HClO4 at ~310°C; details are presented for treatment of different samples. The digest is cooled to room temp., 5 M HCl is added and the solution is diluted. In a simple continuous-flow manifold, sample solution is mixed with 12 M HCl and then 0.6% NaBH4 solution The H2Se produced is separated off by a standard pneumatic neublizer, and Se is determined by ICP-AES at 196.090 nm. The detection limit is 0.4 µg l-1, or 4 µg kg-1 for a nominal 1-g sample. The calibration graph is rectilinear for 4 mg kg-1. The method has been applied to biological tissues and fluids and to water. Results show good agreement with those by AAS and NAA.
Selenium Biological tissue Water Spectrophotometry

"FIA Automatic Dilution System For The Determination Of Metallic Cations In Waters By Atomic Absorption And Flame Emission Spectrometry"
J. Autom. Methods Manag. Chem. 1996 Volume 18, Issue 1 Pages 17-21
JORGE M. P. J. GARRIDO, RUI A. S. LAPA, JOS&Eacute; L. F. C. LIMA, CRISTINA DELERUE-MATOS, and JO&Atilde;O L. M. SANTOS

Abstract: A fully automated FIA dilution system based on the zone sampling technique is described. The system is based on the use of a PC-compatible microcomputer for instrument control and data acquisition and processing. The computer controlled two rotatory valves which selected different portions of the injected sample plug which were then re-sampled toward the detector. The system automatically chose a suitable dilution factor for each sample. The dilution system was coupled to an atomic absorption spectrometer and to a flame photometer for the determination of Ca, Mg, Na, K, Cu, Zn and Fe in highly concentrated water samples. The method allowed up to x 10 000 dilution factors with RSD 3% and a sampling rate of 90 determinations/h.
Cations Environmental Spectrophotometry Spectrophotometry

"Microwave Oven Digestion Procedures And Flow Injection For The Analysis Of Biological Samples"
J. Flow Injection Anal. 1988 Volume 5, Issue 2 Pages 121-131
M. DE LA GUARDIA and A. SALVADOR, J.L. BURGUERA* and M. BURGUERA

Abstract: A review is presented, with 41 references, of the fundamentals of microwave-oven digestion, of modifications necessary for laboratory use, and of applications of the method, particularly in flow injection analysis. The fundamentals of the use of microwave ovens for sample decomposition, the modifications proposed to adapt the commercially available microwave ovens to the laboratory work requirements and the possibilities and applications of those methods in flow injection analysis are discussed
Biological material Clinical analysis Sample preparation Sample preparation

"Rapid Determination Of Total Nitrogen, Phosphorus, Magnesium, Potassium And Amylose In Milled Rice By Flow Injection Analysis"
J. Flow Injection Anal. 1991 Volume 8, Issue 2 Pages 127-135
Hideharu NAKAJ MA and *Ryoichi YANAGIHARA

Abstract: Sample (0.5 g) was digested with 3 mL of concentrated H2SO4 and 1 mL of HCl and then diluted with water. To determine N, 30 µL of the solution was injected into a stream of 6% H2SO4 (0.8 mL min-1) and mixed with 2.5 M NaOH of pH 10 (2 mL min-1), with warming at 30°C, and with an indicator stream (0.1 g of Tecator 5000-0295 mixed indicator, 0.4 g of NaH2PO4 and water to 1 l) (2.8 mL min-1) before detection at 590 nm. When determining P, 100 µL of the solution was injected into a stream of 6% H2SO4 (2 mL min-1), followed by dilution with water (2.8 mL min-1), reaction with a reagent stream [prepared with 4 g of NH4VO3, 270 mL of HNO3, 80 g of (NH4)6Mo7O24 and water to 1 l] (0.8 mL min-1) and detection at 420 nm. Magnesium and K were determined with use of the same apparatus equipped with an atomic absorption spectrophotometer by using 6% H2SO4 as carrier solution and 1% LaCl3 solution as reagent stream. For determination of amylose, 20 mg of the sample was heated at 90°C with 0.5 mL of ethanol and 2 mL of 1 M NaOH for 60 min, cooled, and diluted with H2O; 30 µL of the supernatant solution was injected into a stream of ethanol - 0.1 M NaOH (2 mL min-1) and mixed with 0.1 M NaOH (2.8 mL min-1), ~2% citric acid - Na acetate (2 mL min-1) and iodine solution (1.5 mL min-1) before detection at 620 nm. The coefficient of variation were 4%. Satisfactory results were obtained.
Amylose Magnesium Nitrogen, total Phosphorus Potassium Rice Spectrophotometry

"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 Urine Immunoassay Spectrophotometry Turbidimetry

"Indicator Dilution Measurement Of Mean Transit Time And Flow In A Straight Tube"
J. Phys. E 1974 Volume 7, Issue 1 Pages 51-55
D A Lane and J A Sirs

Abstract: A theoretical analysis has been undertaken of the application of an indicator dilution technique, using bolus injection, to the measurement of flow rate, mean transit time and vessel volume in a straight tube, for both mixed and laminar flow. Under laminar flow conditions, formulae previously utilized may be substantially wrong. Alternative methods and formulae are proposed and experimental confirmation made of their validity over a wide range of flow conditions.
Spectrophotometry

"Multielement Isotope Dilution Analysis By Means Of Radiometric Titration"
J. Radioanal. Nucl. Chem. 1981 Volume 67, Issue 1 Pages 5-14
P. C. A. Ooms, G. P. Leendertse, H. A. Das, U. A. Th. Brinkman

Abstract: A theoretical concept is derived for multielement isotope dilution analysis in a liquid-liquid extraction system. The practical performance is based on radiometric titration. To that purpose a prototype of a titration/extraction vessel with flow injection has been constructed. For calculations of the initial concentrations of the elements of interest from the experimental data, a computer program has been developed.
Mass spectrometry Sample preparation

"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 Blood Serum Urine Spectrophotometry Spectrophotometry

"Sample Pretreatment System For Atomic Absorption Using Flow Injection Analysis"
Lab. Pract. 1981 Volume 30, Issue 7 Pages 719-723
Mindel, B.D.;Karlberg, B.

Abstract: The use of flow injection analysis (FIA) techniques for the preparation of solutions prior to their aspiration into an atomic absorption spectrometer is described. FIA techniques can be used to process liquid samples automatically in order to bring the concentration. of the analyte and of interfering substances to the most suitable level for anal.; it can be used to reduce or increase sensitivity, and to handle samples with high dissolved solids. (SFS)
Metals Spectrophotometry

"Automated Colorimetric Method For Determination Of Chlorine In Geological Materials Using Flow Injection Analysis Technique"
Lab. Rob. Autom. 1990 Volume 2, Issue 2 Pages 83-88
Chan, C.C.Y.

Abstract: Powdered rock sample (0.15 g) was fused with LiBO2 at 860°C and the melt was dissolved in 9% HNO3. After dilution to 15 ml, the solution was mixed with 0.5% Hg(SCN)2 and 0.5 M Fe(NO3) in a carrier flow of 6% HNO3 and the absorbance was measured at 480 nm. The method was applied to 22 geochemical reference samples and gave coefficient of variation from 0.7 to 9.3%; the results agreed closely with those obtained in the literature. The limit of determination was 15 ppm in rock and calibration covered 50 to 500 ppm.
Chlorine Geological Sample preparation Spectrophotometry

"Application Of Sequential-injection Analysis As Process Analyzers"
Lab. Rob. Autom. 1998 Volume 10, Issue 6 Pages 325-337
R. E. Taljaard, J. F. van Staden

Abstract: The development of sequential-injection analysis (SIA) from its mother technique flow injection analysis (FIA) is reviewed. A short historical background is given as well as discussions on the basic principles and operational parameters governing the design of an SLA system. Single-, double-, and multizone systems are described together with more complicated systems including calibration, dilution, extraction, dialysis, titrations, separation, pre-concentration, and systems incorporating mixing chambers.
d-Lactic acid Spectrophotometry

"Automated Continuous Determination Of Chloride In Water By A Flow Injection Technique"
Lihua Jianyan, Huaxue Fence 1997 Volume 33, Issue 1 Pages 11-13
Hong Lincheng, Zhou Xianggen

Abstract: A sample (20 µL) was injected into a carrier stream (1 ml/min) of water in a laboratory-made fully automated continuous-flow injection system that merged with a reagent stream (2.1 ml/min) containing mercury(II) thiocyanate, iron(III) nitrate and polyoxyethylene glycol dodecyl ether in aqueous methanol before passage through a reactor (40 cm x 0.5 mm i.d.) and absorbance measurement at 480 nm. The method was applied to water from a chemicals plant, with recoveries of 98-102% and an RSD (n = 10) of 1.2%. The merging-zone technique is used to reduce reagent consumption, and zone-sampling manipulation to dilute the sample. When the chloride concentration is high, multirange chloride determination is used to avoid reading overflow.
Chloride Waste Spectrophotometry

"FIA Determination Of Magnesium In High Concentration In Bittern Of Carnallite By Gradient Dilution Method"
Lihua Jianyan, Huaxue Fence 1998 Volume 34, Issue 3 Pages 126-127
Zhang, Z.;Chen, Q.;Li, C.;Ren, F.;Xu, J.

Abstract: The FIA determination of Mg in high concentration. bittern of carnallite by gradient dilution method was studied. Mg and chlorophosphonazo III form a complex in a borax-NaOH buffer solution (pH 10.2). The Beer's law was obeyed for 10^-40 mg Mg mL-1 at 530 nm with a RSD of 2.6%.
Magnesium Carnallite Spectrophotometry

"Spectrophotometric Determination Of Ethanol In Blood By Flow Injection Analysis With An Enzyme Reactor Coupled To A Dialyser"
Mitt. Geb. Lebensmittelunters. Hyg. 1990 Volume 81, Issue 2 Pages 209-218
Maeder, G.;Pelletier, M.;Veuthey, J.L.;Haerdi, W.

Abstract: Ethanol is separated from blood by dialysis, then oxidized by NAD+ in the presence of alcohol dehydrogenase, with spectrophotometric determination of the NADH formed. The apparatus (scheme given) consists of a peristaltic pump (Gilson Minipuls 3, an injection chamber (Reodyne 5020; 110 µL capacity), a dialyser (Gilson; 100 µL capacity; equipped with a Cuprophan membrane), an immobilized enzyme reactor (7.5 cm x 1.5 mm), a spectrophotometric detector (SSI-500; equipped with cell 6 mm long, 9 µL capacity) and a HP 3390 A integrator. Blood diluted (1:100) with carrier solution (33.46 g of Na4P2O7.10H2O, 8.03 g of semicarbazide hydrochloride, 1.57 g of glycine, 8.75 g of NaCl and 0.8 g of NAD+ dissolved in water, adjusted to pH 9 with 1 M NaOH, diluted to 1 L with water and filtered) was injected into the chamber, substances of MW >15,000 were retained by the membrane, the fluid was transported to the reactor, and NADH was determined at 340 nm. The results of the determination of ethanol (0.78 to 3.22%) by two enzymatic and two GC methods and those of the determination of C1 to C4 alcohols are tabulated.
Ethanol Blood Spectrophotometry

"Flow Injection Methods: A New Tool For Instrumental Analysis"
Phil. Trans. R. Soc. A 1982 Volume 305, Issue 1491 Pages 645-656
J. Ruzicka and D. Betteridge

Abstract: Gradient flow-injection techniques are reviewed and their use for serial assays and research in instrumental methods of analysis is outlined. The increasing importance of flow injection analysis as a new solution-handling technique in a laboratory is demonstrated with several examples.

"Design Of Flow Injection Manifolds To Give The Best Detection Limits For Methods Involving Online Chemical Derivatization. 1. Theoretical Basis For High Sensitivity"
Quim. Anal. 1989 Volume 8, Issue 2 Pages 171-178
Tyson, J.F.

Abstract: High sensitivity can be achieved by designing a system that allows mixing with minimum dispersion or dilution. For flow injection analysis in which the peak height, corresponding to the product formed online by the inter-dispersion of injectate and reagent, is monitored as the analytical parameter, the same maximum sensitivity is obtained from single- and double-line manifolds. The double-line manifold requires a large volume to be injected and the dispersion coefficient (D) is obtained by a suitable flow rate ratio. Single-line manifolds have a higher throughput than the double-line to achieve the same dispersion.

"Pneumatic Nebulizer As A Dilution Chamber In A Flow Injection System For Multielement Analysis By ICP-MS"
Quim. Nova 1998 Volume 21, Issue 4 Pages 405-409
Gomes Neto, Jos&eacute; Anchieta; Silva, Jos&eacute; Bento B.; Rodrigues Neto, Renato; Curtius, Adilson Jos&eacute;; Souza, Ivan G.

Abstract: An automatic dispenser based on a flow injection system used to introduce sample and anal. solution into an inductively coupled plasma mass spectrometer through a spray chamber is proposed. Anal. curves were constructed after the injection of 20 to 750 µL aliquots of a multielement standard solution (20.0 µg L-1 in Li, Be, Al, V, Cr, Mn, Ni, Co, Cu, Zn, As, Se, Sr, Ag, Cd, Ba, Tl, Pb) and the acquisition of the integrated transient signals. The linear concentration. range could be extended to ~five decades. The performance of the system was checked by analyzing a NiST 1643d reference material. Accuracy could be improved by the proper selection of the injected volume Besides good precision (relative standard deviation <2%), the results obtained with the proposed procedure were closer to the certified values of the reference material than those obtained by direct aspiration or by injecting 125 µL of several anal. solutions and samples.
Lithium Beryllium Aluminum Vanadium Chromium Manganese Nickel Cobalt Copper Zinc Arsenic Selenium Strontium Silver Cadmium Barium Thallium Lead NIST 1643 Mass spectrometry

"Evaluation Of The Operational Parameters Affecting Dispersion In Sequential Injection Analysis"
South Afr. J. Chem. 1998 Volume 51, Issue 2 Pages 100-108
Van Staden, J.F. & Botha, A.

Abstract: Sequential injection analysis (SIA) is known for its use as an analysis technique, having the advantage of reduced sample and reagent consumption compared with flow injection analysis (FIA). An important aspect that needs critical attention in the optimization of this system is the dispersion, which could have a direct effect on the zone penetration that takes place within the SIA flow conduit. The dispersion in the SIA manifold is influenced by certain operational parameters, and studies were carried out to study the effect these parameters have on dispersion. Because of a lack of information on the effect operational parameters have on the dispersion that takes place within an SIA flow conduit, it was decided to study these parameters in depth to contribute to this knowledge. A study was made on the effect mixing chamber have on dispersion within the SIA manifold. The optimized dimensions of the parameters that were studied are: pump tubing internal diameter (internal diameter), 1.85 mm; pump speed, 18.0 rpm (peristaltic pump); sample and reagent zone volumes, 600.0 and 1200.0 µL; holding coil length, (3.50 m) and internal diameter (1.60 mm); reaction coil length (1.10 m) and internal diameter (1.02 mm); and a 1.0 mL mixing chamber in the holding coil position of the SIA manifold.
Sulfate Industrial

"Enhancement Of Fourier Transform Infrared Spectrometry By The Flow Injection Technique: Transmittance And Internal Total Reflectance Cell In A Single-line System"
Vib. Spectrosc. 1991 Volume 2, Issue 1 Pages 1-14
M. Guzman, J. Ruzicka and G. D. Christian, P. Shelley

Abstract: A study was made of the ability of a flow injection analysis (FIA) system to undertake automated dilutions when coupled to an FTIR spectrometer, and to carry out multi-component determinations. A transmittance cell and a cylindrical internal total reflectance (Circle) cell were compared. Ternary mixtures containing 1 to 2% acetone, ethanol and THF in CCl4 were analyzed using the transmittance cell. A stopped-flow method was used with the Circle cell in order to enhance the signal-to-noise ratio, and ternary mixtures with 7 to 60% acetone, 3 to 20% ethanol and 1 to 20% THF in CCl4 were used. The determinations were performed using a multivariate calibration method (partial least squares).
Spectrophotometry

"Principles And Applications Of Flow Injection Analysis"
Z. Chem. 1984 Volume 24, Issue 3 Pages 81-93
Helmut M&uuml;ller, Volkmar M&uuml;ller

Abstract: Principles of flow injection analysis, including dispersion effects, are described, and the system is discussed in terms of its transport, injection, reaction (e.g., dialysis, dilution, extraction and chemical reaction), detection and data-processing components. An extensive table is presented of applications in clinical, pharmaceutical, water and agricultural chemistry, with details of detection systems and detection limits. Special flow injection methods, e.g., the stopped-flow technique, titration, and closed-system operation, are also discussed. (174 references).
Caffeic acid Ferricyanide Agricultural Pharmaceutical Clinical analysis Sample preparation

"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 Urine Biological tissue HPLC

"Serial Dilution Microchip For Cytotoxicity Test"
J. Micromech. Microeng. 2004 Volume 14, Issue 8 Pages 1165-1170
Hyunwoo Bang, Sun Hee Lim, Young Kyung Lee, Seok Chung, Chanil Chung, Dong-Chul Han and Jun Keun Chang

Abstract: Today's pharmaceutical industry is facing challenges resulting from the vast increases in sample numbers produced by high-throughput screening (HTS). In addition, the bottlenecks created by increased demand for cytotoxicity testing (required to assess compound safety) are becoming a serious problem. We have developed a polymer PDMS (polydimethylsiloxane) based microfluidic device that can perform a cytotoxicity test in a rapid and reproducible manner. The concept that the device includes is well adjustable to automated robots in huge HTS systems, so we can think of it as a potential dilution and delivery module. Cytotoxicity testing is all about the dilution and dispensing of a drug sample. Previously, we made a PDMS based microfluidic device which automatically and precisely diluted drugs with a buffer solution with serially increasing concentrations. This time, the serially diluted drug solution was directly delivered to 96 well plates for cytotoxicity testing. Cytotoxic paclitaxel solution with 2% RPMI 1640 has been used while carrying out cancerous cell based cytotoxicity tests. We believe that this rapid and robust use of the PDMS microchip will overcome the growing problem in cytotoxicity testing for HTS.