University of North Florida
Browse the Citations
-OR-

Contact Info

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

View Stuart Chalk's profile on LinkedIn

Rain

Classification: Environmental -> water -> rain

Citations 86

"Stopped-flow Spectrophotometric Determination Of Hydrogen Peroxide With Hemoglobin As Catalyst"
Talanta 2000 Volume 51, Issue 1 Pages 179-186
Ke Zhang, Luyuan Mao and Ruxiu Cai

Abstract: A rapid and sensitive method was proposed for the determination of hydrogen peroxide based on the catalytic effect of hemoglobin using o-phenylenediamine as the substrate. Stopped-flow spectrophotometric method was used to study the kinetic behavior of the oxidation reaction. The catalytic effectiveness of hemoglobin was compared with other four kinds of catalysts. The initial rate of the formation of the reaction product 2,3-diaminophenazine at the wavelength of 425 nm was monitored, permitting a detection limit of 9.2 x 10^-9 mol/l H2O2. A linear calibration graph was obtained over the H2O2 concentration range 5.0 x 10^-8-3.5 x 10^-6 mol/l, and the relative standard deviation at a H2O2 concentration of 5.0 x 10^-7 mol/l was 2.08%. Satisfied results were obtained in the determination of H2O2 in real samples by this method.
Hydrogen peroxide Spectrophotometry Stopped-flow Kinetic Catalysis Interferences Optimization

"Sequential Injection Spectrophotometric Analysis Of Nitrite In Natural Waters Using An On-line Solid-phase Extraction And Preconcentration Method"
Analyst 2000 Volume 125, Issue 5 Pages 943-948
Manuel Miró, Andreu Cladera, José Manuel Estela and Víctor Cerdà

Abstract: An automatic sequential injection analysis (SIA) set-up for the isolation, pre-concentration and spectrophotometric determination of nitrite in waters based on the Shinn reaction was designed and evaluated. The system performs the on-line azo dye formation and its subsequent extraction on a solid phase (monofunctional C-18), which is held inside a glass column incorporated into the system. A large sample volume (maximum, 10 mL) is sequentially segmented with sulfanilamide and N-(1-naphthyl)ethylenediamine dihydrochloride by using an iterative method. The azo dye collected is eluted with a small volume of 80% methanol and conducted to a diode-array spectrophotometer for quantitative analysis. It has been proved that the retention efficiency is maintained for up to 45 sample injections of 10 mL in spite of the high chromogenic reagent acidity. Nitrite has been determined within the 13.4-160 ng mL-1 and 0.83-20 ng mL-1 ranges for 1 and 10 mL of sample, respectively. For these volumes, the detection limits are 5.9 and 0.32 ng mL-1, the enhancement factors 17 and 170 and the sample throughput 15 and 3 h-1, respectively. A maximum RSD of 4.0% was achieved in all determinations. It is an advantage of this approach that it is possible to use the same mass calibration graph for any sample volume.
Nitrite Spectrophotometry C18 Preconcentration Column Solid phase extraction

"Determination Of Ultratraces Of Nitrite By Solid-phase Preconcentration Using A Novel Flow-through Spectrophotometric Optrode"
Anal. Chim. Acta 2001 Volume 437, Issue 1 Pages 55-65
Manuel Miró, Wolfgang Frenzel, Víctor Cerdà and José Manuel Estela

Abstract: A novel sorbent-packed planar wall microcolumn-based optosensor coupled to a flow injection analysis system (FIA) for the determination of traces of nitrite by solid-phase spectrophotometry is presented. The methodology is based on the on-line nitrite derivatization with a modified Griess reagent to form an aze-dye whose retention onto octadecyl-covalently bonded silica gel by physical adsorption and partitioning is continuously monitored. After the analytical signal has been recorded, the sorbed compound is eluted with 80% methanol/water (v/v), rendering the system ready for the next extraction. Selection of the solid support and the suitable flow-through cell configuration are discussed in detail. By minimization of the blank signal, a concentration of nitrite as low as 1 ng/ml can be easily determined using 2.5 mi of sample. Detection limit (3s blank) of 0.46 ng/ml of nitrite, relative standard deviation better than 4%, sample throughput of 12 h-1 and an enrichment factor of 93 in relation to the conventional spectrophotometric method were obtained. The utility of the present optosensing system, wherein a mass calibration is also feasible, was testified by the satisfactory results obtained in its application to tap, rain and aquarium water samples.
Nitrite Spectrophotometry Optrode Optosensing Preconcentration Solid phase extraction Solid phase detection C18

"Multisyringe Flow Injection Spectrofluorimetric Determination Of Warfarin At Trace Levels With On-line Solid-phase Preconcentration"
Anal. Chim. Acta 2002 Volume 467, Issue 1-2 Pages 13-23
Graciela de Armas, Manuel Miró, José Manuel Estela and Víctor Cerdà

Abstract: Warfarin (3-(α-acetonylbenzyl)-4-hydroxycoumarin) is a widely used anticoagulant rodenticide which has strong toxic effects in humans and animals. A new multisyringe flow injection analysis (MSFIA) set-up for the spectrofluorimetric determination of warfarin in waters at trace levels is presented. Preconcentration on a solid-phase (octadecyl chemically-bonded silica-gel-based beads) without prior derivatization, and elution with dimethyl sulfoxide (DMSO) containing monomeric units of the cetyltrimethylammonium chloride (HTAC) surfactant resulted in a quantification limit (50 ng L-1) lower than those reported to date, reaching the levels demanded by regulatory authorities in drinking waters. Several variables such as eluent composition, sample and eluent volumes, retention and elution flow rates and sample pH were studied in detail. A mass calibration may be used to determine warfarin in the wide range from 50 ng L-1 to 64 µg L-1 for sample volumes between 0.2 and 12 mL. An enrichment factor of 155, a sample throughput of 12 hr-1 and a repeatability better than 2% were achieved by pre-concentration of 16 ng of the target compound from 2 mL of sample.
Warfarin Fluorescence Multisyringe C18 Column Preconcentration Review

"A Computer Controlled Multichannel Continuous-flow Analysis System Applied To The Measurement Of Nitrate, Chloride And Ammonium Ions In Small Samples Of Rain Water"
Anal. Chim. Acta 1980 Volume 113, Issue 2 Pages 331-342
J. Slanina, F. Bakker, A. Bruyn-Hes and J. J. Möls

Abstract: A multichannel continuous flow system based on spectrophotometric determinations is described. Samples are injected into a water stream which is then mixed with appropriate reagents by merging flows; this mode improves the background signals. The system is controlled by a PDP 11 computer. Calibration, analysis of samples and quality control are done automatically. The system is applied to the determination of nitrate, chloride and ammonium ions in small ( 0.5 ml) samples of rain water in the range 0.2-20 ppm. The accuracy is typically better than 3%. The sampling rate is 18-35 per hour.
Nitrate Chloride Ammonia Ammonium Spectrophotometry Computer Multichannel

"Ion Exchange In Flow Injection Analysis. Determination Of Ammonium Ions At The µg/l Level In Natural Waters With Pulsed Nessler Reagent"
Anal. Chim. Acta 1980 Volume 117, Issue 1 Pages 81-89
H. Bergamin F, B. F. Reis, A. O. Jacintho and E. A. G. Zagatto

Abstract: Ion exchange was incorporated in flow injection analysis using a resin column in the sample loop of an electronically operated proportional injector. Effects of sample aspiration rate, sampling time, eluting agent concentration, pumping rate of the sample carrier stream, resin column size and sample acidity, were determined to develop a pre-concentration. procedure for NH4+ determination in natural waters at the µg/L level with pulsed Nessler reagent. Sample buffering before the adsorption step was done with a precision of ~2%, a sampling rate of ~40 samples/h, and a reagent consumption of 40 µL/sample, and is almost free of interferences. Recoveries of 95-105% were achieved with rain-water samples with NH4+ contents of <200 µg/L. Alternative flow diagrams and the injector command unit are discussed.
Ammonia Ammonium Ion exchange Spectrophotometry Apparatus Preconcentration Proportional injector Interferences Pulsed reagent

"Utilization Of Flow Injection With Hydrazine Reduction And Photometric Detection For The Determination Of Nitrate In Rain-water"
Anal. Chim. Acta 1981 Volume 124, Issue 2 Pages 437-441
B. C. Madsen

Abstract: The hydrazine reduction method for determination of nitrate at the parts per million level is adapted to flow injection sample processing of rain-water. Reagent composition and physical variables were evaluated and optimized. Forty samples per hour can be processed. A precision of better than 3% is possible in the range of 1.0-10.0 ppm nitrate. Results for nitrate obtained from 9 rain-water samples agreed favorably with those determined by ion chromatography.
Nitrate Spectrophotometry

"Fast Determination Of Anions By Computerized Ion Chromatography Coupled With Selective Detectors"
Anal. Chim. Acta 1981 Volume 130, Issue 1 Pages 1-8
J. Slanina, F. P. Bakker, P. A. C. Jongejan, L. Van Lamoen and J. J. M&ouml;ls

Abstract: Up to 18 samples per hour can be analyzed for chloride, nitrate and sulfate by ion chromatography if the columns are thermostated (at ~40°C) and dead volume is minimized by the use of very small suppressor columns and minimal tubing. Accurate results are obtained from simple samples such as rain-water but nitrite, phosphate and bromide can interfere. These interferences can be avoided by the use of multiple detectors, such as a u.v. monitor at 220 nm and ion-selective electrodes (for fluoride and bromide). For samples containing more than 0.5 ppm of the ions of interest, a sample loop is used directly; the accuracy is typically 2-5%. For lower concentrations, a concentrator column is used with sample volumes up to 4 ml; this results in detection limits of 1-6 ppb for bromide, chloride, nitrate and sulfate. The computerized system is capable of analyzing large series of samples unattended.
Chloride Nitrate Sulfate HPIC Electrode Computer

"Solid-state Chemiluminescence Detector For Hydrogen Peroxide Based On An Immobilized Luminophore. Application To Rain-water"
Anal. Chim. Acta 1985 Volume 174, Issue 1 Pages 151-161
P. van Zoonen, D. A. Kamminga, C. Gooijer, N. H. Velthorst and R. W. Frei, G. G&uuml;bitz

Abstract: The construction and use of a H2O2 detector, based on peroxyoxalate chemiluminescence, is described. The detector consists of a two-bed reactor packed with solid bis-(2,4,6-trichlorophenyl) oxalate(I) and 3-aminofluoranthene as luminophore, immobilized on controlled-pore glass beads. Optimum conditions for pH, solvent and purity of I for flow-independent operation, and four detector configurations are discussed. Samples can be injected into a moving stream or directly into the monitor to provide a manually operated field monitor. The peak height is directly proportional to the concentration. of H2O2 and the log. - log. calibration graph is rectilinear with a slope of 1 from the detection limit (15 nM, signal-to-noise ratio of 3) up to 10 mM. The coefficient of variation (n = 10) for manual injections of samples was 3% at the 0.5 µM level, with a limit of detection of 40 nM. Sample throughputs are 100 h-1 in the flow injection mode and 40 h-1 for manual injection. Results are presented for determination of H2O2 in rain-water.
Hydrogen peroxide Chemiluminescence Controlled pore glass Glass beads Immobilized enzyme Optimization

"Potentiometric Detection In Flow Analysis"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 359-370
K. T&oacute;th, J. Fucsk&oacute;, E. Lindner, Zs. Feh&eacute;r and E. Pungor

Abstract: Flow-through potentiometric detection in flow injection analysis is discussed and the performance characteristics of ion-selective electrodes with respect to rectilinear response, detection limit, selectivity and stability are studied. A method for the determination of F- with a selective electrode in rain-water is described, and a K+-selective electrode described by Tarcali et al. (Anal. Abstr., 1986, 48, 11J139) was applied to the analysis of blood serum. The results were in good agreement with those obtained by ion-chromatographic methods (for F-) and flame-photometric methods (for K).
Potassium Fluoride Electrode Electrode Potentiometry Method comparison Review

"Application Of Ion-selective Electrodes In Environmental Analysis. Determination Of Acid And Fluoride Concentrations In Rain-water With A Flow Injection System"
Anal. Chim. Acta 1987 Volume 194, Issue 1 Pages 163-170
J. Fucsk&oacute;, K. T&oacute;th and E. Pungor, J. Kunovits, H. Puxbaum

Abstract: The flow system consisted of a loop injector, a dispersion tube (1 m x 0.3 mm for acid or 0.6 mm for F-), an indicator electrode and a double-junction silver - AgCl reference electrode. The indicator electrode was a pH-sensitive micro-capillary glass electrode or a flow-through F--selective electrode. Carrier solution for acid determination were either 0.5 M or 1 M KNO3 containing 0.1 mM acetate or phosphate buffer (1 to 1.5 mL min-1) or, for F- determination, a solution containing 3.07 g L-1 of EDTA, 9 g L-1 of NaCl and 1.5 M acetate buffer (pH 5.0 to 5.3) diluted with an equal volume of water, the resulting mixture (1 mL min-1) being made 1 µM in NaF. A nonlinear calibration was obtained at acid concentration. <0.2 mM and with a coefficient of variation of 1% at 0.1 mM with 25 µL samples at an injection rate of 500 to 550 h-1. A rectilinear calibration was obtained for up to 1 µM-F- and with a coefficient of variation of 5% at 1 µM with 250 µL samples at an injection rate of 40 to 60 h-1.
Acidity Fluoride Electrode Electrode

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

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

"Flow Injection Methods For The Microchemical Determination Of Free And Total Acidity In Rain Drops"
Anal. Chim. Acta 1991 Volume 243, Issue 2 Pages 191-200
U. Sprenger and K. B&auml;chmann

Abstract: Flow injection methods were developed for the determination of free and total acidity in water in which acid - base indicators were employed in a gradient mixing technique with spectrophotometric detection. For example, free acidity was determined with use of 50 µM-methyl orange (C. I. Acid Orange 45) - 40 µM-methyl red and detection at 540 nm, and total acidity was determined with use of 40 µM-m-cresol purple - 80 µM-NaOH and detection at 430 nm. The method can be applied to single raindrops. The working range was 4.5 pmol to 2.55 nmol and 450 pmol to 3.73 nmol for free and total acidity, respectively, with corresponding detection limits of 2.42 and 236 pmol.
Acidity Spectrophotometry Gradient technique Mixing

"Flow Analysis For Trace Amounts Of Copper By Ion-exchanger Phase Absorptiometry With 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline Disulfonate And Its Application To The Study Of Karst Groundwater Storm Runoff"
Anal. Chim. Acta 1992 Volume 268, Issue 2 Pages 225-233
Kazuhisa Yoshimura* and Shiro Matsuoka, Youji Inokura, Ushio Hase

Abstract: Water (8.3 mL; containing 0.8 to 80 ng of copper) was introduced into a carrier stream of aqueous 1% (v/v) HCl. Simultaneously, into a second carrier stream comprising 50 g of hydroxylammonium chloride and 200 g of citric acid in 500 mL of water mixed with 10 mL of 4% BL-9EX and adjusted to pH 6 with aqueous NH3 was introduced 2.1 mL of a solution of the cited reagent (50 µg mL-1 in the second carrier stream). The two carrier streams merged and aqueous 10% (v/v) HNO3 was introduced as desorbing agent before passage of the solution through a mixing coil and a flow-through absorptiometric detector containing QAE Sephadex A-25 to concentrate the Cu complex for continuous measurement of absorbance at 484 nm. The system afforded a detection limit of 0.08 ng mL-1 of Cu and selectivity was good. The method was used to monitor the infiltration of storm water from the soil into the underground river of a karst groundwater system. It could also be used to determine Cu in rock samples after microwave digestion with HNO3 and HF. Ion-exchanger phase absorptiometry was applied to flow anal. for trace amounts of Cu in water. The increase in the absorbance of the colored complex with 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline disulfonate, which was concentrated online on to an ion exchanger packed in a flow-through cell, can be measured continuously with a spectrophotometer at 484 nm. The detection limit was 0.08 ng/mL of sample solution. The proposed method permitted a highly sensitive, selective determination of copper in karst groundwater samples without any pre-concentration. By measuring the Cu concentration. response in water after a storm, the infiltration rate of rain water from the soil zone to the underground river of a karst groundwater system was estimated ~10-20 m/day.
Copper Sample preparation Spectrophotometry Solid phase detection Sephadex

"New Interface For Coupling Flow Injection And Capillary Electrophoresis"
Anal. Chim. Acta 1997 Volume 337, Issue 2 Pages 117-124
Petr Kuban, Anders Engstr&ouml;m, Joanna C. Olsson, Gunnar Thors&eacute;n, Robert Tryzell and Bo Karlberg*

Abstract: The plexiglass interface allowed the inlet of the capillary electrophoretic column to be immersed in the effluent from the FIA system. When the sample plug eluted from the FIA system a small fraction was electrokinetically introduced into the column. The performance of the interface was evaluated by analyzing a mixture of 10 anions. A sample volume of 50 µL was injected into a carrier stream (2.7 ml/min) of 60 µM-cetyltrimethylammonium bromide/10 mM chromate/15 mM boric acid of pH 7.5. A potential of 25 kV was applied across the column (80 cm x 50 µm i.d. x 375 µm o.d.; 45 cm to detection window) and indirect UV detection was at 372 nm. The detection limits were 0.1-0.3 µg/ml and the RSD (n = 30) were <2.1%. The sampling frequency was 150/h. The coupled FIA-capillary electrophoresis system was used to determine anion concentrations in drinking and rain water samples.
Anions Electrophoresis Interface Injection technique

"Buffer Composition Suitable For Determining Very Low Fluoride Concentrations Using A Fluoride Ion-selective Electrode And Its Application To The Continuous Analysis Of Rain Water"
Anal. Chim. Acta 1997 Volume 338, Issue 1-2 Pages 141-147
Hirokazu Hara*, and Chun-ching Huang

Abstract: Various buffers were evaluated for determining fluoride in rain water using a continuous-flow system. The most sensitive response was obtained with Sorensen's buffer, a mixture of glycine and HCl of pH 2.8. The continuous-flow system allowed a rain water stream (1 ml/min) to be merged with the buffer stream (0.1 ml/min). The flow was then passed through the detection cell equipped with a fluoride ISE and a double-junction Orion reference electrode. A linear response was obtained for up to 0.1 µM-fluoride and the detection limit was 10 nM. RSD were M and the recovery of 60 nM-fluoride from spiked rain water was 92%. The method was used to continuously monitor fluoride in rain.
Fluoride Potentiometry Electrode Buffer Process monitoring

"Determination Of Free And Total Fluoride In Rain Water Using A Continuous-flow System Equipped With A Fluoride Ion-selective Electrode Detector"
Anal. Chim. Acta 1998 Volume 364, Issue 1-3 Pages 117-123
Hirokazu Hara*, Keiko Yabuuchi, Mayumi Higashida and Masahiro Ogawa

Abstract: A continuous-flow system equipped with a fluoride ion-selective electrode (F- ISE) detector was constructed for the determination of free and total amounts of fluoride in rain water. The buffer system proposed was a mixture of β-alanine (2-aminopropionic acid) and HCl with and without CDTA (1,2-cyclohexanediamine tetraacetic acid). Only one calibration graph is needed to calculate the free and total fluoride concentrations. The detection limit is 1 x 10^-8 mol L-1. The precision of five independent measurements was within 7.3% for 3 x 10^-8 - 1 x 10^-6 mol L-1 standard fluoride solutions. About 50-70% of the fluoride in rain water samples was found to be in free form.
Fluoride Electrode

"Chemiluminescence Flow-sensing System For Hydrogen Peroxide With Immobilized Reagents"
Anal. Chim. Acta 1998 Volume 372, Issue 3 Pages 357-363
Wei Qin, Zhujun Zhang*, Baoxin Li and Shuna Liu

Abstract: A novel chemiluminescence (CL) sensing system for hydrogen peroxide combined with flow injection analysis (FIA) is described. It is prepared by electrostatically immobilizing the anal. reagents, luminol and cobalt(II), on a strongly basic anion-exchange resin and a weakly acid cation-exchange resin, respectively. Hydrogen peroxide is sensed by the CL reaction with luminol and cobalt(II) bleeding from the ion-exchange column with immobilized reagents by hydrolysis. The calibration graph is linear in the range 4 x 10^-8 to 1 x 10^-5 mol L-1, and the detection limit is 1.2 x 10^-8 mol L-1 hydrogen peroxide. A complete anal. could be performed in 1 min with a relative standard deviation of <5%. The system could be used for 50 h and was applied successfully to the determination of hydrogen peroxide in rainwater and glucose in serum by measuring the formation of hydrogen peroxide from a packed bed reactor with immobilized glucose oxidase.
Hydrogen peroxide Glucose Ion exchange Chemiluminescence Immobilized reagent Immobilized enzyme Resin

"Continuous-flow Determination Of Chloride In The Nonlinear Response Region With A Tubular Chloride Ion-selective Electrode"
Talanta 1987 Volume 34, Issue 11 Pages 921-926
Hirokazu Hara* and Yoshiki WakizakaSatoshi Okazaki

Abstract: The tubular electrode is constructed from copper pipe (2 cm x 0.28 cm) plated internally with silver, which is then electro-oxidized in 0.1 M KCl to form a AgCl layer. This electrode is used in conjunction with an Orion double-junction reference electrode containing 1 M NaNO3 in 30% methanol solution as outer filling solution The electrode is incorporated into a microcomputer-aided flow system in which sample or standard solution is mixed with colloidal AgCl solution to remove Br- and I- before the sample is passed through the tubular electrode. The concentration. is interpolated with use of the spline function in the range 0.1 to 10 mg L-1 and the corresponding coefficient of variation were 10 to 2% (n = 5). The detection limit is ~0.1 mg l-1. Results of analysis of rain and snow containing >0.75 mg L-1 of Cl-1 agreed within 10% of those of ion chromatography (n = 12).
Chloride Electrode Potentiometry Computer Method comparison

"Sulfate Preconcentration By Anion-exchange Resin In Flow Injection And Its Turbidimetric Determination In Water"
Talanta 1993 Volume 40, Issue 10 Pages 1529-1534
Marina M. Santos Filha Boaventura F. Reis and Francisco J. KrugCarol H. Collins and Nivaldo Baccan,

Abstract: The flow injection system comprised a computer-controlled sliding-bar automatic injector with three commutation sections in conjunction with a spectrophotometer equipped with a 0.2 mL tubular flow cell (1.2 cm optical path). The resin column (1.5 cm x 6 mm) was machined in a Perspex block and filled with AG 1-X8 resin (200-400 mesh), converted into the nitrate form. The sample was pumped (7 ml/min) for 60 s through a sample loop (20 cm x 0.8 mm) previously loaded with 0.005% sulfate solution and through the resin column, which was then switched into the analytical path for elution (3.2 ml/min) with 0.25 M NaNO3 for 15 s. The eluted sample zone was mixed (1 ml/min) with 0.05% poly(vinyl alcohol) solution in aqueous 20% BaCl2 in a tubular helical reactor coil (100 cm x 0.8 mm) and the turbidity was monitored at 410 nm. Recoveries of standard additions to 17 rain-water samples were ~100%, and for those samples containing 0.1-2 mg/l of sulfate the RSD (n = 10) were 2%. The sample rate was 48 per h. There was negligible interference from 30 mg/l of chloride, nitrate or carbonate and a 12% decrease in absorbance from 0.05 mg/l of sulfate in the presence of 30 mg/l of phosphate.
Sulfate Ion exchange Turbidimetry Preconcentration Resin Column Interferences Multicommutation

"Potentiometric Flow Injection Determination Of Trace Hydrogen Peroxide Based On Its Induced Reaction In Iron(III)-iron(II) Potential Buffer Containing Bromide And Molybdenum(VI)"
Talanta 1996 Volume 43, Issue 6 Pages 943-950
Nobuhiko IshibashiHiroki Ohuraa, Toshihiko Imatob,* and Sumio Yamasakia

Abstract: Sample was injected into a carrier stream (1 ml/min) of water which then merged with a reagent stream (1 ml/min) of 0.1 mM Fe(III)/Fe(II) buffer solution containing 0.4 M NaBr, 0.5% Mo(VI) and 1 M H2SO4. The resultant stream passed through a reaction coil (100 cm) to a flow-through oxidation-reduction potential electrode detector with a Ag/AgCl reference electrode and a Au-plates oxidation-reduction potential electrode. The detection limit was 0.4 µM-H2O2 with a RSD (n = 6) of 0.6% for 4 µM-H2O2. The method was applied to the determination of H2O2 in rain with recoveries of 95.8-104.1%.
Hydrogen peroxide Potentiometry

"Measurement Of Rainwater PH By Optosensing Flow Injection Analysis"
Analyst 1988 Volume 113, Issue 2 Pages 301-306
Bruce A. Woods, Jaromir Ruzicka, Gary D. Christian, Norman J. Rose and Robert J. Charlson

Abstract: An immobilized indicator on a cellulose pad is placed in a PVC flow injection microconduit channel. The color change of the indicator is monitored by reflectance spectrometry as the sample passes through the single-line system. Bifurcated fiber optic bundles are used to transmit radiation between the flow cell and the light source and spectrophotometer. Effects due to metal ion interference, variations in sample buffer capacity and carrier buffer capacity were studied. With a sample volume of 75 µL, and a carrier solution of 0.5 mM acetate (pH 5.73), the coefficient of variation ranged from 0.0 to 2.0% for dilute HCl standards. Results agreed well with those obtained by an electrode method.
pH Spectrophotometry Cellulose Immobilized reagent Interferences Manifold comparison Optical fiber Optimization Optosensing

"Continuous-flow Determination Of Sulfate With A Lead-selective Electrode"
Analyst 1988 Volume 113, Issue 12 Pages 1817-1820
Hirokazu Hara, Gy&ouml;rgy Horvai and Ern&ouml; Pungor

Abstract: The continuous-flow system (described and illustrated) was applied in the determination of SO42- in rain-water. The sample stream (1.0 mL min-1) was merged with the reagent solution (2.5 mL min-1) of 10 µM-Pb(NO3)2, 10 mM NaClO4 (I adjuster) and 10 µM-Na acetate - 1 mM acetic acid buffer in aqueous 98.6% ethanol, and the solution was mixed in a coil (2 m x 0.8 mm); SO42- was detected indirectly by using a solid-state Pb-selective electrode. The calibration graph was curvilinear from 0.01 to 1 mM SO42-. The coefficient of variation for 0.02 to 0.5 M SO42- were 5% (n = 5). There was interference from Ca, Cl and PO43-. The results were compared with those of ion chromatography; those of the proposed method were consistently greater by 27%.
Sulfate Electrode Potentiometry Calibration Indirect Interferences Method comparison Titrations

"Interference Study On A Continuous-flow Determination System For Sulfate With A Lead-selective Electrode Detector And Its Application To Natural-water Analysis"
Analyst 1990 Volume 115, Issue 8 Pages 1077-1083
Hirokazu Hara and Shigetsugu Mori

Abstract: The previously described method (cf. Ibid., 1988, 113, 1817), in which SO42- is determined indirectly by reaction with Pb(NO3)2 and detection with a Pb-selective electrode, was further studied. The interference caused by HCO3-, Cl-, Ca, NO3- and PO43- was studied, and the composition of the reagent was optimized. Even in the presence of an acidic buffer, HCO3- caused positive interference. A concentration.-dependent interference by Cl- was interpreted in relation to the dynamic response of the electrode. The optimum reagent comprised 1 mM monochloroacetic acid - 10 mM NaClO4 in ethanol also containing 10 or 50 µM-Pb(NO3)2 for analysis of rain or river water, respectively.
Sulfate Electrode Interferences Buffer Optimization

"Gel-phase Absorptiometry Of Phosphate With Molybdate And Malachite Green And Its Application To Flow Analysis"
Analyst 1990 Volume 115, Issue 6 Pages 843-848
Kazuhisa Yoshimura, Sawako Nawata and Genichiro Kura

Abstract: Phosphate in water was determined by formation of an ion-association complex with ammonium molybdate - C. I. Basic Green 4, then either, (i) adsorption onto Sephadex LH-20 beads which were then packed into a 5-mm cell for absorbance measurement at 627 and 750 nm vs. air; the difference between the absorbance at the two wavelengths was proportional to the PO43- concentration, or (ii) concentration online onto the gel in a flow-through cell for measurement of the absorbance at 627 nm. For procedure (i) calibration graphs were rectilinear for up 10 µg L-1 of PO43-; the detection limit was 0.6 µg l-1. For procedure (ii) calibration graphs are plotted for up to 3 µg l-1; the rectilinear range varied with sample volume. Recoveries were 98 to 105%; detection limit (flow injection procedure) was 75 ng l-1. The method was applied to softened-, rain-, ground-, river and seawater.
Phosphate Spectrophotometry Flowcell Detection limit Calibration Sephadex Solid phase detection Ion pair formation

"Flow Injection Amperometric Determination Of Trace Amounts Of Ammonium Using A Gas Diffusion Cell As The Sample Loop"
Analyst 1995 Volume 120, Issue 12 Pages 2845-2848
Renmin Liu, Bianting Sun and Ian Johns

Abstract: A new flow injection method for the determination of trace amounts of ammonium by using a pyrolytic graphite electrode electrodeposited with a cuprihexacyanoferrate film coated with Nafion film as a sensor is described. A gas diffusion unit was used to enhance the selectivity and sensitivity, Under optimum analytical conditions, the linear range of the calibration graphs for ammonium were 2-32, 0.8-16 and 0.4-8 µmol L-1 when the accumulation time was 1, 2 and 3 min, respectively, The method has been applied to the determination of ammonium in rain-water samples and recoveries of 96.7-102.2% were obtained, The s(r) values of seven replicate analyzes for all samples were 1.6-2.5%. (22 references)
Ammonia Amperometry Electrode Electrode Gas diffusion Optimization

"Online Flow Injection Cobalt-ammonium Pyrrolidin-1-yldithioformate Coprecipitation For Preconcentration Of Trace Amounts Of Metals In Waters With Simultaneous Determination By Inductively Coupled Plasma Atomic-emission Spectrometry"
J. Anal. At. Spectrom. 1994 Volume 9, Issue 7 Pages 779-784
Zhixia Zhuang, Xiaoru Wang, Pengyuan Yang, Chenlong Yang and Benli Huang

Abstract: Rain was adjusted to pH 3 with dilute HNO3 or ammonia solution and spiked with 20 µg/ml of Co(II) as coprecipitant. The mixture was pumped (3.3 ml/min) and merged with a stream (0.4 ml/min) of 2% ammonium pyrrolidin-1-yldithioformate. The precipitate was collected on a PTFE membrane, washed with methyl isobutyl ketone, dissolved in HNO3/H2O2 (1:1) and carried to the ICP nebulizer for determination of Cd, Cu, Fe, Ni, Pb and Zn. Detection limits were 0.2-1 µg/g. Recoveries were >93%. RSD (n = 6) were 1.9-5 %.
Cadmium Copper Iron Nickel Lead Zinc Spectrophotometry Preconcentration Coprecipitation MIBK Teflon membrane

"Flow Injection And Photometric Determination Of Sulfate In Rainwater With Methylthymol Blue"
Anal. Chem. 1981 Volume 53, Issue 12 Pages 1924-1926
Brooks C. Madsen and Richard J. Murphy

Abstract: The automated methylthymol blue method for determination of sulfate has been adapted to flow injection sample processing. Prominent features of the method include a linear calibration curve up to 6 mg/L, approximate sensitivity of 0.1 mg/L, and sampling rate of 20 per hour. Average precision was 4.1% and average accuracy evaluated by comparison of results with those obtained by ion chromatography was 97%.
Sulfate Spectrophotometry

"Flow Injection And Photometric Determination Of Hydrogen Peroxide In Rainwater With N-ethyl-N-(sulfopropyl)aniline Sodium Salt"
Anal. Chem. 1984 Volume 56, Issue 14 Pages 2849-2850
Brooks C. Madsen and Mark S. Kromis

Abstract: The flow system consisted of a single mixed-reagent stream and a carrier stream (H2O), both pumped at 4.5 mL min-1 to merge before passage through a 2.9-m mixing coil and a 1-cm-pathlength flow-through cell for measurement of the absorbance at 560 nm. The sample volume was 0.58 mL. The mixed reagent was 2 mM in the cited compound (cf. Tamaoku et al., Anal. Abstr., 1982, 43, 5B26) and 0.8 mM in 4-aminoantipyrine and contained 23 mg L-1 of peroxidase in phosphate buffer solution of pH 5.83. The calibration graph was rectilinear for 40 µM-H2O2, the detection limit was ~0.14 µM, and a sampling rate of 80 h-1 was possible. No interference was observed on addition of Mn(II) and Fe(III), both of which interfere in the luminol chemiluminescence procedure.
Hydrogen peroxide Chemiluminescence Spectrophotometry Interferences

"Continuous-flow Real-time And Flow Injection Determination Of Rainwater PH With A Poly(vinyl Chloride)-based Tubular Membrane Electrode"
Anal. Chem. 1987 Volume 59, Issue 1 Pages 127-130
Brooks C. Madsen and Donald W. Doller

Abstract: Rain-water samples were studied by continuous-flow real-time and flow injection analysis with a tubular flow-through electrode incorporating a pH-sensing membrane containing tris-(2-ethylhexyl)amine, bis-(2-ethylhexyl) sebacate, Na tetraphenylborate and PVC (5:325:3:165). Calibration graphs were rectilinear from pH 2.7 to 5.0 and the sampling rate for the flow injection method was 60 h-1.
pH Electrode Electrode

"Fluorimetric Measurement Of Aqueous Ammonium Ion In A Flow Injection System"
Anal. Chem. 1989 Volume 61, Issue 5 Pages 408-412
Zhang Genfa and Purnendu K. Dasgupta

Abstract: The test solution (14 µL), containing NH3 or NH4+, is injected into a carrier stream (50 µL min-1) of water freed from NH3 and NH4+ by cation exchange, and the stream is mixed with 10 mM phthalaldehyde in aqueous 25% methanol (50 µL min-1) in a knotted coil and then with 3.0 mM Na2SO3 in 0.1 M phosphate buffer of pH 11.0 (50 µL min-1). The mixture is heated for ~40 s in a stainless-steel coil at 85°C (unnecessary at high NH4+ concentration.) and its fluorescence is measured at >425 nm (excitation at 351 nm). The detection limit is better than 20 nM-NH4+. The method is unaffected by NaCl concentration, and response to amino-acids is slight. The method has been used to determine NH4+ in tap- and lake water and rain.
Ammonium Fluorescence Buffer Interferences Detection limit Knotted reactor Selectivity Method comparison

"Quantitative Determination Of Aqueous-phase Ozone By Chemiluminescence Using Indigo-5,5'-disulfonate"
Anal. Chem. 1989 Volume 61, Issue 6 Pages 619-623
Koji Takeuchi and Takashi Ibusuki

Abstract: The cited reagent (I; C. I. Food Blue 1) was used to determine O3 in aqueous solution from the chemiluminescence generated in a continuous-flow system (diagram presented). The optimum reagent composition was 10 mg L-1 of I in 2 mM phosphate buffer (pH 7.2). The calibration graph was rectilinear from 25 ng L-1 to 410 µg L-1 of O3; the limit of detection was 6 ng l-1, three orders of magnitude lower than that by spectrophotometry with use of I. The method should be applicable to environmental samples such as rain and fog.
Ozone Chemiluminescence Buffer Method comparison Optimization

"Determination Of Ammonium Ion In Rain-water And Fog Water By Flow Injection Analysis Wtih Chemiluminescence Detection"
Anal. Chem. 1993 Volume 65, Issue 23 Pages 3489-3492
Xincheng Hu, Norimichi Takenaka, Shiro Takasuna, Masaru Kitano, Hiroshi Bandow, Yasuaki Maeda, and Masaharu Hattori

Abstract: Rain-water was collected in a funnel-topped polypropylene bottle and fog water was collected from flowing air on PTFE strands (0.435 mm). Samples were filtered and 1.2 mL was injected into a stream (10 ml/min) of water, which was merged with a stream (10 ml/min) of NaBrO solution (0.3% of Br in 1 M NaOH/1 M NaBr) in an arrangement of concentric tubes. The resulting chemiluminescence was measured in a scroll glass tube (15 cm x 2 mm i.d.) similar to that of Burguera et al. (Anal. Chim. Acta, 1980, 114, 209), a glass 690 nm filter being placed between the cell and the photomultiplier tube to remove interfering emission from, e.g., 5 µM-urea and 1 ppm of humic acid. The maximum chemiluminescence developed within 20 ms of mixing the reactants; pH was without effect in the range 3-11. The calibration graph was linear for 0.01-1 mM NH4 with a detection limit of 6.1 µM. Results obtained agreed well with those from ion chromatographic and indophenol spectrophotometric methods. Reaction between ammonia and hypobromite in alkaline solution was found to give chemiluminescence. The maximum wavelength of the chemiluminescence is 710 nm. This chemiluminescence reaction has been used for the determination of ammonium ion concentration in rainwater and fogwater with a flow injection analysis system. The detection limit of ammonium ion was 6.1 10^-6 mol/L (3 RSD). The dominant components in rainwater such as NO3-, SO42-, and Cl-, do not interfere with the determination, but humic acid and urea do. The interference can be removed by inserting a glass filter between the chemiluminescence cell and the photomultiplier tube, because the peak wavelengths of the emission are different for both chemiluminescence species. Rainwater and fogwater samples can be rapidly determined by this method without any pretreatment. The results determined by the present method were in good agreement with the ion chromatographic method and the indophenol spectrophotometric method. Copyright 1993, American Chemical Society. .
Ammonium Chemiluminescence Method comparison Interferences

"Flow Injection Analysis Of Sulfate With A Potentiometry-based Linear Calibration Graph"
Anal. Chem. 1995 Volume 67, Issue 13 Pages 2299-2303
Tzyh-Chyang Tang and Hsuan-Jung Huang

Abstract: The sample was pumped through a column (30 cm x 3 mm i.d.) of PbSO4 (80-120 mesh), and the emerging solution, containing Pb(II) ions, was filtered before passage, in 0.1 M NaClO4 carrier, to a detector equipped with a Pb(II)-selective electrode and a Ag/AgCl (3 M NaCl) reference electrode. All solutions contained 35% of methanol to enhance the sensitivity. The optimum flow rates for delivery of the sample or standard solution and the reacted solution plus carrier were 0.3 and 0.9 ml/min, respectively. The system was washed out with a blank solution for 4 min between measurements. Calibration was effected with 4-120 µM-sulfate added to a solution containing 6 µM-sulfate. The calibration graph was linear over the cited range, and the detection limit was 1 µM. Interference from anions that react with Pb(II) could be detected by curvature of the calibration graph. Additive errors were caused by heavy metal ions. Chloride (90.2 mM) interfered in the determination of 75 µM-sulfate. The method was applied to rainwater, and the result agreed to within ±10% with that of ion chromatography.
Sulfate Potentiometry Electrode Interferences Method comparison

"A Fast Determination Of Nitrate In Rain And Surface Waters By Means Of UV Spectrophotometry"
Fresenius J. Anal. Chem. 1976 Volume 280, Issue 5 Pages 365-368
J. Slanina, W. A. Lingerak and L. Bergman

Abstract: Organic substances are the main interference in the direct U.V. spectrophotometric determination of nitrate at 210 nm. An active carbon filter (Filopur) is therefore proposed which adsorbs all organic interferences. With this filter the U.V. spectrophotometric method gives the same results as the Na-salicylate method. The reproducibility is generally better than 5 %. One determination takes 50 s.
Nitrate Spectrophotometry Activated carbon

"Fast Determination Of Nitrate In Small Samples Of Rain And Surface Waters By Means Of UV Spectrophotometry And Flow Injection Analysis"
Fresenius J. Anal. Chem. 1978 Volume 289, Issue 1 Pages 38-40
J. Slanina, F. Bakker, A. G. M. Bruijn-Hes and J. J. M&ouml;ls

Abstract: An UV-spectrophotometric determination of NO3- in small samples (0.5 mL) of rain and surface waters is described. A variant of flow injection analysis is used in combination with an active C filter for removal of organic interferences. The accuracy and the reproducibility of the method are >3%. One determination takes 30 s.
Nitrate Spectrophotometry Activated carbon Interferences Small sample

"Flow Injection Determination Of Sulfate In Environmental Samples Using Dimethylsulfonazo(III) As Indicator"
Fresenius J. Anal. Chem. 1979 Volume 295, Issue 5 Pages 410-412
H. F. R. Reijnders, J. J. van Staden and B. Griepink

Abstract: SO42- is determined in flowing percolation water, potable water, and rainwater by injection of a colorimetric reagent containing dimethylsulfonazo III into a flow-through cuvette of a recording photometer.
Sulfate Spectrophotometry

"Flow Analysis For The Determination Of The Main Components Of Waters, Rain Water And Drinking Water"
Fresenius J. Anal. Chem. 1983 Volume 314, Issue 7 Pages 627-633
H. F. R. Reijnders, P. H. A. M. Melis und B. Griepink

Abstract: A survey of the literature concerning flow-through determination of the main components in various types of water is given. These components are: alkalinity, chloride, nitrite, nitrate, phosphate, sulphate, ammonium, potassium, lithium, sodium, barium, calcium, magnesium and strontium. Details with regard to e.g. type of water, range of the method, interferences etc. are given in a separate compilation which is available from the editor upon request.
Alkalinity Ammonium Barium Calcium Chloride Lithium Magnesium Nitrate Nitrite Phosphate Potassium Sodium Strontium Sulfate Review

"Determination Of Sulfate In Natural Water By Flow Injection Analysis"
Fresenius J. Anal. Chem. 1984 Volume 317, Issue 1 Pages 29-31
Susumu Nakashima, Masakazu Yagi, Michio Zenki, Mitsuo Doi and Kyoji T&ocirc;ei

Abstract: Dimethylsulfonazo III was used as reagent and the absorbance was measured at 662 nm. Interference by Ca was eliminated by inserting a column (8 to 15 cm) of Amberlite IR-120B resin (H+ form; 20 to 50 mesh) just after the sample-injection valve. To ensure good sensitivity and reproducibility, the carrier solution was saturated with BaSO4 and the reaction coil was filled with aqueous 50% ethanol when not in use. At a level of 10 mg L-1 of SO42-, the following (concentration. in mg l-1) did not interfere within 5% negative error: Mg and NH4+ (30); Na (50); K (80); and Cl-, NO3-, PO43-, HCO3- and SiO32- (100). The calibration graph was rectilinear up to 14 mg L-1 (K2SO4 standard). The coefficient of variation (n = 20) at 6 and 10 mg L-1 were 0.94 and 1.2%, respectively. In 9 separate samples of natural rain, tap, well and river waters, recoveries of added SO42- (4 and 6 mg l-1) ranged from 95 to 105%. A Shimadzu double-beam spectrophotometer with a 1-cm flow-through micro-cell (8 µL) was used, and the flow rates for both the reagent and carrier solution were 1.7 mL min-1. The sample solution (130 µL) was injected via a 6-way valve into the carrier stream. Flow lines were made of PTFE tubing (1 mm or 0.5 mm i.d.). The limit of detection was ~0.2 mg l-1. A flow diagram of the apparatus is given.
Sulfate Ion exchange Spectrophotometry Amberlite Interferences

"Determination Of Ammonium In Aerosols, Cloud And Rain Water, And Of Gaseous Ammonia In The Troposphere"
Fresenius J. Anal. Chem. 1987 Volume 327, Issue 1 Pages 16-16
U. Sprenger and K. B&auml;chmann

Abstract: Four methods were compared for the determination of NH4+. An UV - visible spectrophotometric determination is described which involved treatment of NH4+ with an alkaline solution of 4,4'-bis-(3-methyl-1-phenylpyrazolin-5-one) in the presence of chloramine T at pH 6, extraction with trichloroethylene after acidification, and measurement of the absorbance at 455 nm. Two flow injection analysis methods are described involving injection of a sample into a stream of NaOH to produce NH3 which diffuses across a permeable membrane into a flowing acceptor stream. In the first method, the acceptor is bromothymol blue solution and the absorbance is measured at 620 nm, and in the second, the acceptor is water and the change in conductivity is measured. The last method described involves ion chromatography and conductivity detection. The sample volume, detection limits, reproducibilities and analysis times are given for the four methods. A possibility for sampling gaseous NH3 is by formation of ammonium oxalate on cellulose filters coated with oxalic acid.
Ammonium Spectrophotometry Cellulose Gas diffusion Membrane Method comparison

"Amperometric Flow Injection Technique For Determination Of Hydrogen Peroxide And Sulfur(IV) In Atmospheric Liquid Water"
Fresenius J. Anal. Chem. 1989 Volume 335, Issue 8 Pages 919-923
I. G. R. Gutz and D. Klockow

Abstract: Hydrogen peroxide and S(IV) were determined in atmospheric water (200 µL) by flow injection analysis with electrochemical oxidation in a specially designed micro-cell (described and illustrated) with an alkaline carrier stream for H2O2 and an acidic carrier stream for S. Differential measurements before and after addition of catalase or sulfite oxidase were taken using an amperometric detector. Sample throughput was 30 h-1. The electroactive species could be determined from 20 nM (detection limit) to mM levels. The method was applied to rain, snow, fog and cryosampled atmospheric water vapor. Sulfur(IV) present as hydroxymethanesulfonate or in the form of other carbonyl adducts was determined after alkaline decomposition to liberate SO32-.
Hydrogen peroxide Sulfur Amperometry Enzyme

"Flow Injection Spectrophotometric Determination Of Calcium In Rain And Snow With Chlorophosphonazo III"
Fresenius J. Anal. Chem. 1990 Volume 338, Issue 6 Pages 707-709
Michio Zenki, Kikuko Ohmuro and Kyoji T&ocirc;ei

Abstract: A two-fold manifold (diagram given) is used for the determination of Ca in rain and snow based on the complex formation with chlorphosphonazo III in the presence of 0.01 M oxalate (pH 2.8). Barium, Sr and rare-earth metals interfered. Under optimum conditions, the calibration curve was rectilinear up to 1.2 ppm Ca and the detection limit was 0.01 ppm for 120 µL of sample. The coefficient of variation for 0.4 and 1.0 ppm Ca were 0.354 and 0.352%, respectively. Results agreed well with those obtained by AAS.
Calcium Spectrophotometry pH Interferences Method comparison Detection limit Optimization

"Development Of Analytical Methods For The Determination Of Ions And Acidity In Individual Raindrops"
Fresenius J. Anal. Chem. 1991 Volume 340, Issue 9 Pages 548-552
K. B&auml;chmann, I. Haag, U. Sprenger, K.-H. Steeg, K. Steigerwald, B. Bastian and A. R&ouml;der

Abstract: Raindrops are frozen in liquid N and separated by size fractionation with use of mesh sieves. Several analytical procedures are also described for the determination of ions at ultratrace levels and with volume 1 µL; free and total acidity of the drops are determined by the reaction with suitable acid/base indicators in a flow-injected system with gradient mixing and UV - visible spectrophotometric detection. Alkaline- and alkaline-earth-metals are determined on microbore cation-exchange columns of ION-210 metals and Fast Cation 1 with Ce as mobile phase. Formate, Cl-, NO3- and SO42- anions are separated on a column of PRP X-100 with 3 mM Na2CO3 buffer - 6% acetonitrile - 0.17 mM p-cyanophenol as mobile phase and with conductivity detection. Acetate, formate, pyruvate and methane sulfonate are separated on a column of HPIC AS5A with Na2B4O7 as mobile phase. Iron, Pb and Mn are determined from size fractions by graphite-furnace AAS. Detection limits are given.
Acidity Spectrophotometry Spectrophotometry Column Ultratrace

"Amperometric Determination Of Hydrogen Peroxide With A Manganese Dioxide Film-modified Screen Printed Carbon Electrode"
Fresenius J. Anal. Chem. 1998 Volume 362, Issue 2 Pages 194-200
Klemens Schachl, Hailemichael Alemu, K. Kalcher, Helmut Moderegger, Ivan Svancara, Karel Vytras

Abstract: A carbon thick film electrode modified with an MnO2-film was investigated as an amperometric detector for H2O2 in flow injection analysis (FIA). At an operating potential of +0.48 V vs. Ag/AgCl catalytic oxidation of the analyte was exploited for amperometric monitoring. Experimental parameters, such as pH of the carrier, working potential, flow rate, and injection volume were optimized. The amperometric signals were linearly proportional to the concentration. of H2O2 in the range from 0.005-10 mg/L, showing a detection limit (3s) of 2.3 µg/L. The method was applied to the determination of H2O2 in rainwater and to a simple assay to quantify glucose in human plasma.
Hydrogen peroxide Glucose Amperometry Electrode Electrode Electrode Sensor Apparatus Detector Optimization

"Flow Injection Analysis Of Trace Hydrogen Peroxide Using An Immobilized Enzyme Reactor"
Microchim. Acta 1985 Volume 87, Issue 1-2 Pages 77-87
Hoon Hwang and Purnendu K. Dasgupta

Abstract: Sub-ppb levels of H2O2 in aqueous solution were determined by reaction with 4-hydroxyphenylacetic acid in a flow injection enzymatic system with use of a single-bead-string reactor, comprising horse-radish peroxidase covalently bound by glutaraldehyde to Ambersorb XE-347, for catalysis. A perfluorosulfonate cation-exchange membrane reactor immersed in aqueous NH3 was used to raise the pH of the mixture from 5.5 (the reaction pH) to 10 before fluorimetry of the fluorogen dimer at 412 nm (excitation at 329 nm). The dynamic range of rectilinear response was 1 ppb to 1 ppm, with a detection limit of 0.3 ppb and a sample throughput of 40 h-1. Organic peroxides act as inhibitors of the enzyme, and cannot be determined by this method. Application to rainwater samples is described.
Hydrogen peroxide Ion exchange Fluorescence Catalysis Immobilized enzyme Single bead string reactor Membrane Ambersorb

"Potassium Permanganate-octylphenyl Polyglycol Ether Chemiluminescence System For FIA Determination Of Hydrogen Peroxide"
Microchim. Acta 1997 Volume 126, Issue 1-2 Pages 73-76
Manliang Feng, Zheng Li, Jiuru Lu and Hailong Jiang

Abstract: A mixture solution of aqueous H2O2/octylphenyl polyglycol ether was injected into a flow (2 ml/min) of mixed H2SO4/KMnO4 solution, which then passed through a flow cell for chemiluminescence detection (wavelength not given). The calibration graph was linear from 0.01-60 µM-H2O2, the detection limit was 6 nM and the RSD (n = 7) for 40 nM- to 4 mM H2O2 solutions were 1.6-2.3%. The sampling rate was 60/h. The tolerance of the method to interferents was investigated. The maximum tolerable amounts of interferents are listed. The method was also applied to rain. Results were comparable to those obtained by a fluorescence method (cf. Cheng, 'Fluorescence Analysis', Science Press, China, 1990, p 427) and RSD were 2.3-2.9%. Details of the optimization of the method (i.e. concentrations, flow rate and choice of reagents) are given.
Hydrogen peroxide Chemiluminescence Detection limit Interferences Method comparison Optimization

"Hyphenated Techniques Combined With Atomic Spectrometry For Environmental Studies"
Microchem. J. 1995 Volume 51, Issue 1-2 Pages 88-98
Wang X. O., Zhuang Z. X., Yang P. Y. and Huang B. L.

Abstract: The development and application of hyphenated techniques combined with atomic spectrometries for environmental analysis at Xiamen University, China, are described. The techniques include: flow injection online microcolumns combined with AAS, GFAAS, ICP AFS and ICP-AES for trace and ultratrace analysis of water; flow injection online solvent extraction combined with AAS and ICP-AES; flow injection online hydride generation for the elemental analysis of Chinese herbs and rain by AAS and ICP-AES; flow injection online coprecipitation-dissolution for the determination of trace heavy metals in seawater and rain by GFAAS and ICP-AES; and HPLC combined with ICP-AES for multielement speciation analysis of Chinese tea.
Metals, trace Metals, heavy HPLC Fluorescence Spectrophotometry Spectrophotometry Spectrophotometry Spectrophotometry Spectrophotometry Sample preparation Review Coprecipitation Solvent extraction Volatile generation Speciation Ultratrace Volatile generation

"Flow Injection Determination Of Hydrogen Peroxide Using A Carbon Paste Electrode Modigied Witha Manganese Dioxide Film"
Anal. Lett. 1997 Volume 30, Issue 15 Pages 2655-2673
Klemens Schachl; Hailemichael Alemu; Kurt Kalcher; Jitka Jezkova; Ivan Svancara; Karel Vytras

Abstract: The parallel C paste electrodes of a thin-layer flow cell were coated with a MnO2 film by passing deaerated NH3/NH4Cl buffer (buffer A) containing 20 mg/l Mn2+ (as chloride) through the cell at 0.5 ml/min whilst applying 0.6 V for 60 min. Rain water (100 ml) was mixed with 100 l buffer A and a portion (50 l) of the solution was injected into a flow (1 ml/min) of 0.2 M buffer A which then passed through the thin-layer flow cell for detection of H2O2 at 0.46 V vs. Ag/AgCl. The calibration graph was linear from 1-450 mg/l H2O2, the detection limit was 4.7 g/l H2O2, the RSD (n = 10) at 10 g/ml H2O2 was 2.3% and the electrodes were stable for 14 days. The effects of interferents are tabulated. Recoveries of H2O2 from spiked rain water were 97.9-102%.
Hydrogen peroxide Amperometry Electrode Electrode Interferences

"A Fluorescence-based Sensor For Ammonium And Nitrate"
Anal. Lett. 1998 Volume 31, Issue 4 Pages 555-567
Satoshi Sasaki; Yoshihiro Ando; Makiko Dejima; Yoshiko Arikawa; Isao Karube

Abstract: Measurement of nitrite and nitrate in rain samples was performed using a fluorescence-based sensor. Nitrite and nitrate were reduced to ammonia using Devarda's alloy, and the gas was then passed through a membrane and reacted with o-phthaladehyde. A linear relationship between the nitrate concentration and the luminescence intensity was observed over the concentration range of 1-5 mg/l, with a relative standard deviation (RSD) of 2.3% at a nitrate concentration of 1 mg/l (n = 5). The system did not show any response toward sulfate or chloride. Results obtained from the measurement of river water samples using the sensor showed good agreement with those obtained using a conventional method.
Ammonium Nitrate Nitrite Fluorescence Method comparison Membrane Interferences

"Chromatographic Methods For The Analysis Of Size-classified And Individual Raindrops"
J. Chromatogr. A 1993 Volume 643, Issue 1-2 Pages 181-188
Knut B&auml;chmann, Ingo Haag, Thomas Prokop, Andreas R&ouml;der and Petra Wagner

Abstract: Rain, collected by allowing the drops to fall into liquid N and freeze, was analyzed by micro-HPLC, CZE and FIA. Two cation-exchange columns, (10 cm x 0.5 mm) of ION-210 and (15 cm x 0.5 mm) of Fast Cation 1 were used to determine alkali and alkaline-earth metals by micro-HPLC with column switching for Na+, NH4+, K+, Mg2+ and Ca2+, Ce(III) as eluent and fluorescence detection at 320 nm (excitation 251 nm). A column (12.5 cm x 4.6 mm) of dodecylamine-coated Optisil ODS (5 µm) with hexacyasoferrate as eluent and indirect UV detection was used for anions. CZE was carried out on polyimide-coated fused-silica capillaries of 60 cm x 75 µm (55 cm to detector) and used UV detection. This method required a small injection volume (~10 nl) allowing small samples to be analyzed several times. Automatic sample injection was also possible. Micro-HPLC had lower detection limits and was used to analyze single rain drops where low concentration. were encountered. Detection limit and RSD for six anions, six cations by micro-HPLC and CZE are tabulated. FIA with UV detection was rapid and highly reproducible and was used to determine pH values.
pH Spectrophotometry

"Low-pressure Ion Chromatography"
J. Chromatogr. A 1994 Volume 671, Issue 1-2 Pages 23-28
Xinshen Zhang* and Xiaoping Jiang

Abstract: Two types of instrument, a low-pressure fast analysis ion chromatograph and a low-pressure transition metal ion chromatograph, were used with conductivity and optical detectors, respectively, in the analysis of a variety of ions. Both systems were operated at 30-40 psi using 30 mm long columns packed with spherical particles of ion exchanger. The conditions are described for the determination of alkali metals and NH4+, alkaline earth metals, inorganic anions and organic acids using conductivity detection and transition metals using post-column derivatization with a chromogenic reagent and optical detection. An improved conductivity cell is described which has an electrode at the solution entry end for high sensitivity. The detection limit for each ion was generally 10-9 g/ml. The technique was applied to the analysis of acid rain and Chinese medicines and the determination of Na+, K+ and chloride in blood and Fe2+, Zn2+ and Mn2+ in oilfield water.
Metals, alkali Metals, alkaline earth Metals, transition Ammonium Anions, inorganic Acids, organic HPIC Chromogenic reagent

"Gas-phase Chemiluminescence Detection Of Trace Arsenic In Environmental Water"
Anal. Sci. 1990 Volume 6, Issue 3 Pages 425-430
K. FUJIWARA, A. KURAMOCHI and H. TSUBOTA

Abstract: The method involves conversion of As into AsH3, mixing the AsH3 produced with O3 and measurement of the resulting chemiluminescence. The apparatus used is illustrated schematically. For determination of total inorganic As, concentrated HCl was added to the sample to 2M, and for total As, the sample was treated with 15% NaOH - 5% K2S2O8 for 1 h at 80°C to 85°C, 40% KI - concentrated HCl for 20 min at room temp., and then 10% ascorbic acid before analysis. The method allowed determination of As at 1 ng mL-1. The method was applied to rain, seawater and condensed atmospheric moisture. Results were slightly higher than those obtained by flow injection analysis - AAS.
Arsenic Chemiluminescence Method comparison Volatile generation Volatile generation

"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 Ion exchange Column Dilution Calibration Muromac

"Flow Injection Spectrophotometric Determination Of Micro Amounts Of Sulfate Ion In Surface- And Seawater Samples With A Barium Chromate Reaction Column"
Anal. Sci. 1994 Volume 10, Issue 1 Pages 77-81
A. SAKURAGAWA, S. NAKAYAMA and T. OKUTANI

Abstract: An aqueous carrier solution comprising 4.5 M sodium acetate and 4% ethanol was pumped into a flow system of stainless-steel tubing (0.5 mm i.d.) at 0.8 ml/min. Water (50 µL) containing sulfate was injected into the carrier stream and the solution was passed through a cation-exchange column (5 cm x 4 mm i.d.) of Dowex 50W-X4 (100-200 mesh) followed by a reaction column of the same size packed with 0.5 g of BaCrO4 powder. The chromate ion concentration, which corresponded to the sulfate ion concentration, was monitored by a photometric detector at 370 nm and peak heights were used for quantification. The calibration graph was linear from 0.5-5 ppm of sulfate and the RSD was 0.75% for 3 ppm of sulfate (n = 10). Interference by cations was eliminated by the use of the exchange column and that by anions was reduced by the choice of carrier solution The method was used to determine sulfate in sea-, well- and rain-water; recoveries were 98-101% with RSD of 1.6-3.5% (n = 7).
Sulfate Spectrophotometry Interferences

"Catalytic Spectrophotometric Determination Of Picogram Amounts Of Vanadium In Natural Fresh And Tap Water By Flow Injection Analysis"
Anal. Sci. 1996 Volume 12, Issue 2 Pages 237-242
S. KAWAKUBO, K. KAJIHARA and M. IWATSUK

Abstract: A spectrophotometric FIA method for the analysis of V down to 0.001 µg/l, based on its catalytic effect on the oxidation of o-phenylenediamine (OPDA) with bromate at pH 4 and 50°C in the presence of gallic acid as an activator, is presented. Portions (200 µL) of standard V solutions were injected directly into a carrier stream of water (0.8 ml/min) of a flow injection manifold (schematic shown) previously described by Kawakubo et al. Analyst [Cambridge, UK], 1995, 120, 2719). The carrier stream was merged sequentially with three reagent streams (0.2 ml/min), 14 mM gallic acid solution containing 1.5 M acetic acid and 0.35 M sodium acetate buffer of pH 4, 0.07 M OPDA and 0.7 M bromate solution in a reaction coil (4 m x 0.5 mm i.d.) in a temperature-controlled water bath and the oxidized OPDA produced was detected at 450 nm. The calibration graph was linear up to 8 µg/l for both V(IV) and V(V) and the detection limit and sampling frequency were 4 ng/l (0.8 pg) and 30 samples/h, respectively. The detection limit was 10-times lower than that obtained by the previous fluorimetric method (loc. cit.). Tolerance levels for five foreign ions (listed) and humic acid are given. The method was successfully applied to the analysis of lake, river, ground, rain and tap water samples with recoveries of 100-105%.
Vanadium Spectrophotometry

"An Automated Ion Analyzer"
Am. Lab. 1985 Volume 17, Issue 2 Pages 92-97
Ranger, C.B.

Abstract: An automated system is described that incorporates flow-injection anal. and ion chromatography, allowing both techniques to be performed either sequentially or simultaneously using a single instrument. Several examples, including anion determination in acid rain sample, Fe determination in presence of Pu, Ni and Zn determination in phosphate bath, are given to illustrate the performance of the system. Several levels of sample preparation can be incorporated in-line to provide complete automation. (SFS)
Anions Iron Automation Review

"Catalytic Determination Of Vanadium By Micro Ion Exchange Separation-flow Injection Method And Its Application To Rain Water"
Bunseki Kagaku 1984 Volume 33, Issue 11 Pages 609-614
Fukasawa, T.;Kawakuba, S.;Okabe, T.;Mizuike, A.

Abstract: Sample solution (2.5 ml) in 20 mM HCl - 0.1% H2O2 is passed through a column (4.5 cm x 1.7 mm) of Amberlite CG-400. The column is washed with 0.5 mL of the same solvent mixture, followed by 1 mL of 20 mM HCl. Vanadium is eluted with 0.2 mL of 2 M HCl, the pH is adjusted to 8 to 9 with aqueous NH3 and the solution is diluted to 0.25 mL with water. An aliquot (0.1 ml) is injected into a stream of 0.25 M NaBrO3 - 30 mM gallic acid (pH 3.8) for the catalytic spectrophotometric determination of V at 380 nm. From 0.1 to 5 ng of V can be determined within 40 min. Tolerance levels of Al, Fe(III), Mo(VI) and W(VI) are 5, 100, 25 and 50 µg, respectively. The method was applied in the determination of V in rain.
Vanadium Ion exchange Spectrophotometry Amberlite Catalysis Interferences Resin

"Continuous Measurement Of Sulfate Ion In Environmental Water Samples By FIA"
Bunseki Kagaku 1990 Volume 39, Issue 9 Pages T129-T133
Korenaga, T.;Okada, K.;Takahashi, T.;Moriwake, T.

Abstract: The determination of SO42- in water samples, e.g., rain and snow, was achieved by using a FIA sensing device equipped with a double plungent micropump; an aqueous 80% ethanol solution containing a Ba - sulfonazo III complex and EDTA was used as color reagent for SO42-. Results agreed well with those obtained by the official titration method (r = 0.99). The coefficient of variation was 0.5% and the detection limit was 0.02 mg L-1 of SO42-. The method was applied to waste water.
Sulfate Spectrophotometry Method comparison Detection limit

"Flow Injection Analysis For Hydrogen Peroxide Using A Titanium(IV) - Porphyrin Complex"
Bunseki Kagaku 1993 Volume 42, Issue 6 Pages 363-367
Matsubara, C.;Nakamichi, N.;Kawamoto, N.;Takamura, K.

Abstract: A sample of rain-water was mixed with an acid solution of oxo-[5,10,15,20-tetrakis-(4-pyridyl)porphyrinato]titanium(IV) in a reaction coil (15 m x 0.5 mm) at 75°C. Absorbance was measured as peak height at 450 nm. The response was rectilinear from 10 nM to 10 µM H2O2 (detection limit 5 nM) with coefficient of variation (n = 10) of 1% for 1 µM H2O2.
Hydrogen peroxide Spectrophotometry

"Determination Of Formaldehyde In Water By Chemiluminescence After Derivatization"
Bunseki Kagaku 1993 Volume 42, Issue 8 Pages 439-443
Takeuchi, K.;Takahashi, H.;Kutsuna, S.;Ibusuki, T.

Abstract: Water was mixed with 4 mM 4-amino-3-penten-2-one (pH 5) and the mixture was heated at 60°C for 40 min in order to derivatize any formaldehyde (I) present before injection into a FIA system at 0.2 ml/min. The sample stream was merged with a stream of bis-(2,4,6-trichlorophenyl)-oxalate solution in acetone (0.5 ml/min) and a stream of H2O2 in aqueous 20% acetone (1.3 ml/min) and chemiluminescence detection was used for the determination of I. The detection limit was 9.3 ng/ml and the calibration graph was rectilinear up to 70 µg/ml. No details of RSD or recoveries are given. The method was successfully applied to the analysis of rain.
Formaldehyde Chemiluminescence

"FIA Of Fog- And Rain-water Acidity"
Bunseki Kagaku 1993 Volume 42, Issue 10 Pages 631-633
Suzaki, H.;Okochi, H.;Igawa, M.

Abstract: The acidities of samples at pH 4.8 and 8.3 were determined by FIA using carbonate-free 1 mM NaOH as carrier solution and Bromothymol blue and Bromophenol blue, respectively, as indicators. The half-width of the signal peak was used for the calibration. The results obtained using FIA generally agreed well with those obtained by a titration method. The pH 8.3 acidity determined by FIA and the total acidity determined by titration were always greater than the H+ concentration due to the presence of NH4+ and organic acids.
Acidity Spectrophotometry Method comparison

"Fluorimetric Flow Injection Analysis Of The Total Amounts Of Low-molecular-weight Aldehydes In Rain Water"
Bunseki Kagaku 1998 Volume 47, Issue 4 Pages 225-231
Harumitsu Nishikawa*, Hideki Nagasawa and Tadao Sakai**

Abstract: A 3-channel flow injection (FI) spectrofluorimetric anal. of the total amounts of low-mol.-wt. aldehydes in rain water with cyclohexane-1,3-dion (CHD) was developed. The stable baseline was obtained by delivering reagent (0.1% CHD) and buffer (6.6 M AcONH4-AcOH, pH 5) solutions sep. A reaction temperature of 90°C was necessary for a highly sensitive anal. of aldehydes. The other optimum conditions were: reaction coil length 0.5 mm i.d. x 5 cm, cooling coil length 3 m, sample size 150 µL, flow rate of the carrier solution 1.0 mL/min, flow rate of the reagent and buffer solutions 0.25 mL/min, and excitation and emission wavelengths at 376 and 452 nm. The calibration graph was linear in over the range 10^-100 ppb of formaldehyde. The relative standard deviation for 10 standard formaldehyde solutions (50 ppb) was <1%. This rapid and sensitive FI method was applied for an anal. of the total amounts of aldehydes, calculated as formaldehyde, in rain water. The method is useful for determining water-sol. aldehydes amounts as an index value of organic pollution in rain water.
Aldehydes Fluorescence Heated reaction Optimization

"Determination Of Chloride Ion By Flow Injection Cathodic-potentiometric Stripping Analysis"
Fenxi Huaxue 1993 Volume 21, Issue 3 Pages 263-266
Li, Z.Y.;Zhang, S.S.

Abstract: The system used (diagram given) for the cited determination consisted of a flow-through electrolytic cell equipped with a Ag silk as a working electrode and a reference SCE, a pump to deliver carrier stream (0.1 M NaNO3) and a sampling injector. Ethanolic 0.1% Arsenazo I solution was added to sample solution, causing the stripping peak height to increase. Sample solution merged with the carrier stream (1 mL min-1) and was passed through the electrolytic cell, electrolysed at +0.3 V for 5 s and the constant-current stripping curve was recorded. The relationship between the stripping peak height and Cl- concentration. was rectilinear from 1 µM to 8 mM Cl-. The method was used to determine Cl- in tap, ground and rain water.
Chloride Potentiometric stripping analysis Electrode Apparatus Detector

"Flow Injection Spectrophotometric Determination Of Trace Hydrogen Peroxide"
Fenxi Huaxue 1995 Volume 23, Issue 6 Pages 678-680
Gao, J.Y.;Qin, X.Y.

Abstract: A 120 µL portion of sample was injected into a stream of water (4 ml/min) and mixed with a reagent stream (prepared from 100 mL 0.1 M NaOH/0.1 M Na2CO3 buffer of pH 12, 40 mL sodium calconcarboxylate (1 mg/ml), 60 mL 240 µg/ml of Cu(II) diluted to 1000 mL with H2O) at 3.2 ml/min in a reactor (100 cm long) at 25°C. The absorbance difference was measured at 555 nm. The calibration graph was linear from 0.1-2.4 µg/ml of H2O2 (I). The method was applied to the analysis of I in rain water. Recoveries were 99-103% for 0.42-2.08 µg/ml of I and the RSD (n = 5) were 0.9-2.5% over the same concentration range. There was little interference. Sampling frequency was 120 runs per h.
Hydrogen peroxide Spectrophotometry Interferences

"Online FIA Preconcentration Of Zinc In Acid Rain And Determination By Hollow Cathode Lamp-ICP AFS"
Fenxi Shiyanshi 1995 Volume 14, Issue 1 Pages 50-52
Gong, Z.B.;Wang, X.R.;Ying, H.;Huang, B.

Abstract: Flow charts for pre-concentration and elution processes are presented. Rain was mixed with acetate buffer solution of pH 7 and 0.1% quinolin-8-ol, the mixture was passed through a column (15 x 4 mm i.d.) packed with 60-80 mesh active carbon at a flow rate of 1.6-1.8 ml/min and elution was effected with 2 M HNO3 at the same flow rate. The eluate was passed to the ICP AFS instrument with a r.f. generator power of 700 W, a carrier flow rate of 1.5 l/min, cooling gas flow rate of 10^-12 l/min, viewing height of 135 cm, hollow cathode lamp current of 8 mA and measurement wavelength of 213.9 nm. The detection limit was 0.089 ng/ml of Zn. Results are compared with those obtained by ICP AES.
Zinc Fluorescence Preconcentration

"Determination Of Ultratrace Amounts Of Metal Ions By Graphite-furnace Atomic Absorption Spectrophotometry With Online Flow Injection Preconcentration. 1. Determination Of Copper In Snow, Rain And Other Water Samples"
Henliang Fenxi 1993 Volume 9, Issue 1-2 Pages 32-36
Yang, C.L.;Zhuang, Z.X.;Yang, P.Y.;Wang, X.R.

Abstract: Sample was pre-concentration 32-fold on a PTFE cartridge (1.5 cm x 2.4 mm) of CPPI (not defined) resin (self-made; 60 mesh) washed with 2 M HNO3, then transferred to a graphite-furnace by automated sample introduction. The heating cycle involved drying at 110°C for 50 s, ashing at 700°C for 10 s, atomization at 2000°C for 3 s and cleaning at 2300°C for 3 s. The calibration graph was rectilinear from 1 (detection limit) to 900 pg/g of Cu, and the RSD was 4%.
Metals Copper Spectrophotometry Preconcentration Ultratrace

"Spectrophotometric Determination Of Fluoride In Acid Rain, Groundwater And Tap Water With Lanthanum/alizarin Complexone By Flow Injection Analysis"
Huanjing Huaxue 1988 Volume 7, Issue 4 Pages 39-44
Ma, Huichang; Yu, Ping; Feng, Jainzhang; Pang, Shuwei

Abstract: The optimum conditions in a flow injection analysis method for fluoride determination in water include the use of La/alizarin complexone at 1:1 ratio in 40% acetone as the chromogenic reagent solution and distilled water as the carrier liquid. The reaction coil is 600 cm long and the reaction temperature is controlled at 50°C. The linear range of the working curve was 0.02-4.0 ppm fluoride. The proposed method permits analysis of ~120 samples/hr. for fluoride in acid rain, groundwater, and tap water.
Fluoride Spectrophotometry Complexation Heated reaction Optimization

"Flow Injection Spectrophotometric Analysis Of Iron Speciation In Natural Water"
Huanjing Huaxue 1989 Volume 8, Issue 4 Pages 35-40
Xu, Quan; Yuan, Xiushun

Abstract: Iron speciation in water was studied using the flow injection-spectrophotometric method. The color-development reaction of Fe2+ and 1,10-phenanthroline was used. Under optimum conditions, Fe3+ was reduced by solid ascorbic acid for the determination of total Fe before the samples were injected. Beer's law was applicable within 0-2.5 ppm ranges of Fe(II); a detection limit of 0.02 ppm was obtained. The relative error is ±0.05 ppm when the concentration of Fe(II) and Fe(III) is 1 ppm. The relative standard deviation for 2 ppm Fe2+ is 0.5% in five measurements. The method can be used at a rate of 250 injections/h. Fe(II) and Fe(III) were determination in aqueous phases and in suspension matter in rainwater and tapwater and lake water with satisfactory results.
Iron(2+) Iron(III) Spectrophotometry Injection technique Speciation Optimization

"Flow Injection Chemiluminescence Analysis And Its Application"
Huaxue Tongbao 1992 Volume 18, Issue 4 Pages 42-46
Li, G.H.;Yu, Z.N.

Abstract: A flow system was developed, based on the lumninol - CN- - Cu(II) system, and applied to the determination of Cu(II) in well, rain and lake water. Sample was filtered through a 0.454 µm filter paper and the filtrate was diluted with 10 mM Na4P2O7. The solution was injected into a flow coil in which a solution containing 0.033 mM luminol, 13.36 µg mL-1 of CN- and 0.033 M NaOH had merged with 0.1 M NaOH, and the chemiluminescence was measured. The calibration graph was rectilinear from 0.4 ng mL-1 to 0.8 µg mL-1 of Cu(II). The detection limit was 10 pg mL-1 of Cu(II). Recoveries were quantitative. The method was also applied to the determination of Co and Cr in natural water, Pb in waste water and H2O2 in tap water.
Cobalt Chromium Copper Chemiluminescence

"Determination Of Zinc, Cadmium, Lead And Copper In Precipitation By Computerized Differential Pulse Voltammetry"
Int. J. Environ. Anal. Chem. 1985 Volume 19, Issue 2 Pages 85-98
Lingerak, W.A.;Van Wensveen Louter, A.M.;Slanina, J.

Abstract: A computerized flow injection analysis - differential pulse anodic-stripping voltammetric system is described and illustrated. Rain-water samples are made 0.2 M in HNO3 and filtered through Ederol 69K activated-carbon-impregnated filters, which retain organic matter; the metals are carried by buffered electrolyte solution to the flow-through cell, with a mercury-drop electrode, for deposition and anodic stripping. The system is controlled by an Apple II computer (details given). From 12.4 to 56.6 ppb of Zn, 0.18 to 0.76 ppb of Cd, 4.9 to 32.7 ppb of Pb and 0.8 to 7.9 ppb of Cu were determined by means of a calibration graph without the need for standard additions, and results were in agreement with those obtained by AAS. Application of the method to seawater, surface water and acid digests of biological samples is discussed.
Zinc Cadmium Lead Copper Electrode Sample preparation Voltammetry Computer Method comparison

"Flow Injection Analysis Of Hydrogen Peroxide, Sulfite, Formaldehyde And Hydroxymethanesulfonic Acid In Precipitation Samples"
Int. J. Environ. Anal. Chem. 1987 Volume 31, Issue 2-4 Pages 263-279
Keuken, M.P.;Bakker, F.P.;Lingerak, W.A.;Slanina, J.

Abstract: A flow injection apparatus was constructed (illustrated schematically), which permits such analyzes. Determination of H2O2 involved amperometric oxidation with Pt working and auxiliary electrodes at 250 mV (Ag - AgCl reference electrode). The detection limit was 5 µg L-1 and the response was rectilinear up to 5 mg l-1. Selective and sensitive spectrophotometric detection of SO32-, formaldehyde and hydroxymethanesulfonic acid is described. For SO32- the reaction involved di-4-pyridyl disulfide; indirect procedures for the organic analytes are described. The limit of detection was 50 µg L-1 and response was rectilinear up to 5 mg l-1.
Hydrogen peroxide Sulfite Formaldehyde Hydroxymethanesulfonic acid Amperometry Spectrophotometry Electrode Indirect

"Determination Of Iron(II) And Hydrogen Peroxide In Atmospheric Liquid Water By Peroxyoxalate Chemiluminescence"
Int. J. Environ. Anal. Chem. 1995 Volume 60, Issue 2-4 Pages 361-375
U. Quass; D. Klockow

Abstract: he chemiluminescence reaction of oxygen with bis(2,4,6-trichlorophenyl)oxalate (TCPO) in the presence of Fe(II) has been investigated under the analytical and mechanistic point of view. Its suitability for the determination of Fe(II) as well as H2O2 in atmospheric liquid water by using a new static fiberoptic luminometer (FOL) and a flow-injection analysis (FIA) system is demonstrated. Results obtained so far suggest, that chemiluminescence is generated by superoxide ion (O2-) produced by autoxidation of Fe(II) through dissolved oxygen. The analytical method based on this reaction shows high sensitivity and detection limits below 100 nM Fe(II). Its application to rain water analysis indicates that Fe(II) and H2O2 may be coexistent in the atmospheric liquid phase.
Iron(2+) Hydrogen peroxide Chemiluminescence Speciation

"Flow Injection Analysis Of Iron In Rain Water With Thiocyanate And Surfactant"
J. Autom. Methods Manag. Chem. 1997 Volume 19, Issue 2 Pages 45-50
A. N. TRIPATHI, S. EHIKHALIKAR, and K. S. PATEL

Abstract: Filtered rain water (5 ml) was oxidized with 0.2 mL concentrated HNO3 and a portion (370 µL) was injected into a stream (4 ml/min) of water which merged with reagent solutions of 1.3 M ammonium thiocyanate, 0.07% cetylpyridinium chloride and 0.05 M HCl/0.05 M H2SO4 (1:1) which were aspirated through tubes of 1.14, 0.51, 0.51 and 0.38 mm diameter, respectively. The optimum coil length of the merging zone was 30 cm (0.5 mm diameter). Sample throughput was 90/h at 4 ml/min flow rate. The optimal rise, injection and delay times were 1, 15 and 25 s, respectively. Detection was at 490 nm. No interference was observed. The detection limit was 8 ppb Fe and the calibration graph was linear for 30-3000 ppb. The RSD (n = 6) at 300 ppb was 0.9%. The results agreed with those obtained by AAS. To determine Fe(III) only, sample was analyzed before oxidation.
Iron Iron(III) Spectrophotometry Speciation Method comparison Optimization Surfactant Interferences Merging zones

"Flow Injection Analysis Of The Species Relavent To Acid Rain"
J. Flow Injection Anal. 1993 Volume 10, Issue 1 Pages 100-102
T. Aoki

Abstract: A brief review is presented of flow injection systems which are available for the determination of SO2, HNO3 and HNO2 in acid rain. (2 references).
Sulfur dioxide Nitric acid Nitrous acid Review

"Determination Of Sulfate In Environmental Water By Spectrophotometric Flow Injection Analysis"
Eisei Kagaku 1998 Volume 44, Issue 1 Pages 49-53
Takashi KORENAGA, Yi YANG, Kensuke SHIBATA, Junko MOTONAKA, Sanae IKEDA

Abstract: Sulfate ion in environmental water was determined by flow injection analysis using barium-dimethylsulfonazo-III complex as the reagent at a rate of 12 samples per h. The linearity and sensitivity were investigated using EtOH- or DMSO (DMSO)-water as solvent, respectively. DMSO-water medium was beneficial in the determination of a low concentration. of sulfate below 3 mg L-1. The calibration curve was linear in the range of 0.1-7 mg L-1 with the correlation coefficient of 0.999. The detection limit was 0.1 mg L-1. The relative standard deviation for 10 injections of SO42- (5 mg/ L-1) was 1.8%. The results of actual sample anal. agreed satisfactorily with those obtained by ion chromatography
Sulfate Spectrophotometry Complexation Method comparison

"Flow Injection Analysis For Hydrogen Peroxide In Environmental Waters"
Kankyo Seigyo 1998 Volume 20, Issue 1 Pages 22-26
Iwado Akimasa; Mukuno Takashi; Akizawa Hiromichi; Mifune Masaki; Saito Yutaka

Abstract: We tried to determine a low-level hydrogen peroxide by using a flow injection analysis (FIA) which was reported in our previous paper. For this purpose , the constituents of the system including the catalytic column were re-examined in detail. As the result, we developed a new system of the FIA which is available for the determination of ppb-level hydrogen peroxide. When hydrogen peroxide spiked in rain-waters (57-944 ppb) was analyzed by the FIA, better recovery and reproducibility were attained compared to chemiluminescent analyzes. The lower-limit of determination was 10 ppb hydrogen peroxide.
Hydrogen peroxide Method comparison Catalysis

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

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

"Determination Of Hydrogen Peroxide In Rain-water By Flow Injection Analysis With Titanium(IV) - 4-(2-pyridylazo)resorcinol Reagent"
Nippon Kagaku Kaishi 1991 Volume 1991, Issue 5 Pages 430-432
Matsubara, C.;Sakai, K.;Takamura, K.

Abstract: A 100 µL sample is flow-injected into a carrier stream of water to the pre-column filled with Amberlite IR-120B before mixing with 0.24 mM Ti - 4-(2-pyridylazo)resorcinol (I) reagent (pH 2.1) and with 0.1 M ammonium buffer of pH 10.7; both mixing coils (130 cm x 0.5 mm) were heated in a thermostat bath at 60°C (all flow-rates were 0.2 mL min-1). Spectrophotometric detection of Ti(IV) - I - H2O2 was by measurement at 508 nm (ε = 36,000). By standard-additions method, recovery was 95.9 to 101.4% and coefficient of variation was 0.8%. Determination range was 1.36 (detection limit) to 1360 ppb of H2O2.
Hydrogen peroxide Spectrophotometry Buffer Column Heated reaction pH PPB Amberlite Standard additions calibration

"Determination Of Hydrogen Peroxide With Sensors Based On Heterogenous Carbon Materials Modified With Manganese Dioxide"
Sci. Pap. Univ. Pardubice, Ser. A 1998 Volume 3, Issue 1 Pages 41-55
Schachl, K.;Alemu, H.;Kalcher, K.;Jezkova, J.;Svancara, I.;Vytras, K.

Abstract: Three different types of MnO2-modified electrodes were investigated for their electrochemical response toward hydrogen peroxide: a bulk-modified carbon paste electrode, a film-modified carbon paste electrode and a film-modified screen printed electrode. The sensors were characterized by voltammetric (cyclic voltammetry, linear sweep voltammetry) and amperometric methods (stationary and flow conditions). The best responses were obtained with a MnO2 film-modified screen printed carbon electrode which could be used as an electrochemical detector in flow injection analysis (FIA) using a NH3/NH4Cl buffer (0.2 M, pH 9.5) as a carrier. With FIA a detection limit (3s) of 0.26 µg L-1 could be achieved; the peak current was linear to the H2O2 concentration from 1 to 200.000 µg L-1. The method could be successfully applied to the determination of H2O2 in various samples (cosmetic and medical products, rain water). With flow injection a sample frequency of 60 h-1 can be achieved.
Hydrogen peroxide Electrode Electrode Electrode Apparatus Detector Buffer

"Flow Injection Analysis. Spectrophotometric Determination Of Sulfate Ions In Atmospheric Deposits"
J. Anal. Chem. 1987 Volume 42, Issue 9 Pages 1631-1635
Eremina, I.D.;Shpigun, L.K.;Zolotov, Y.A.

Abstract: A Tecator flow injection analysis-Star 5020/003 analyzer. with a spectrophotometric detector is used for determining 0.2 to 20 mg L-1 of SO42- in rain and melted snow. A 200 µL sample is injected into a carrier stream of pure water (2 mL min-1) and, after passing through a column (15 cm x 4 mm) of KU-2 cation exchanger (H+ form) to remove interfering metal ions, the sample zone is merged with a stream of standard solution (1.4 mL min-1) containing 10 mg L-1 of SO42-. Thereafter the stream is mixed with a stream of reagent (0.75 mL min-1) containing 25 µM-BaCl2 and 31 µM-3-(2-carboxyphenylazo)-6-(2-sulfophenylazo)chromotropic acid(I); 30-cm mixing coils are used. The decrease in absorbance of the Ba(II) - I complex at 620 nm is related to the concentration. of SO42- in the sample. Sample throughout is 40 h-1; the coefficient of variation are <2% (n = 8). The manifold must be washed with 50 mM Na2EDTA periodically to remove pptd. BaSO4.
Sulfate Spectrophotometry Interferences Tecator

"Flow Injection Analysis. Spectrophotometric Determination Of Chloride Ions In Atmospheric Precipitation"
J. Anal. Chem. 1989 Volume 44, Issue 3 Pages 399-403
Eremina, I.D.;Shpigun, L.K.;Zolotov, Y.A.

Abstract: Chloride was determined in rain-water by using a Tecator FIAstar-5020 flow injection analyzer. and a FIA-5023 spectrophotometer set at 530 nm. A constant flow (1.2 mL min-1) of 0.05 M H2SO4 was maintained through the apparatus while the sample (200 µL) was injected. The mixed stream was passed over a layer of solid Hg(II) chloranilate, and the absorbance of liberated chloranilate ions in the reaction mixture was measured. The Cl- concentration. was found from a calibration graph, which was rectilinear from 0.5 to 75 mg l-1. Fluoride, I-, PO43-, Fe(II), Pb and Zn interfered. The analysis rate was 90 h-1.
Chloride Spectrophotometry Tecator Interferences Solid phase reagent

"Flow Injection Analysis. Spectrophotometric Determination Of Fluoride In Atmospheric Precipitations"
J. Anal. Chem. 1990 Volume 45, Issue 3 Pages 462-467
Eremina, I.D.;Shpigun, L.K.;Dedkova, V.P.;Zolotov, Y.A.;Savvin, S.B.

Abstract: The method is based on the catalytic effect of F- on the reaction of Zr(IV) with 2,7-bis(2-hydroxy-3-sulfo-5-chlorophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (sulfochlorophenol S; I). Rain-water or melted snow (200 µL) was injected into a carrier stream of water (2 mL min-1) which was merged successively with reagent streams (0.6 mL min-1) of (i) 0.1 mM I in 23 mM HCl - 77 mM glycine - 77 mM NaCl buffer (pH 2.8) and (ii) 0.1 mM ZrOCl2 in 0.1 M HCl. The mixture was passed through a reaction coil and the absorbance was measured at 640 nm. A computer-controlled Tecator FIA star-5020 analyzer. was used with a throughput of 90 samples h-1. From 0.02 to 2 mg L-1 of F- could be determined. Calcium and SO42- ions interfered at >20 and >40 mg l-1, respectively. The coefficient of variation for 0.3 to 0.4 mg L-1 of F- were 3%.
Fluoride Spectrophotometry Catalysis Automation Interferences Tecator

"Flow Injection Analysis. Spectrophotometric Determination Of Ammonium And Hydrogen Carbonates In Atmospheric Precipitations"
J. Anal. Chem. 1993 Volume 48, Issue 1 Pages 35-42
Eremina, I.D.;Shpigun, L.K.;Zolotov, Y.A.

Abstract: Sample (200 µL) was added intermittently to a flow of water (2 ml/min) by a peristaltic pump and mixed with 0.1 M NaOH (for the determination of NH4+) or 0.2 M H2SO4 (for the determination of bicarbonate) in a mixing spiral before entering the gas diffusion cell. The NH3 or CO2 gas was separated by a porous PTFE membrane and was merged with the color reagent stream comprising phenol red or bromocresol purple (50 mg/l) for the determination of ammonium or bicarbonate ions, respectively. The absorbance change was measured at 565 nm (phenol red) or 590 nm (bromocresol purple). Calibration graphs were linear from 0.1-5 mg/l and 0.5-20 mg/l of ammonium and bicarbonate ions, respectively. The corresponding RSD were 1-2% and 2-3%.
Ammonium Bicarbonate Spectrophotometry Teflon membrane Gas diffusion

"A Capillary-based Amperometric Flow Immunoassay For 2,4,6-trichlorophenol"
Anal. Bioanal. Chem. 2003 Volume 375, Issue 1 Pages 125-132
Catalin Nistor and Jenny Emn&eacute;us

Abstract: This paper describes the development of two different capillary-based heterogeneous competitive flow immunoassay formats (capillary flow injection immunoassay (CFIIA) and capillary sequential injection immunoassay (CSIIA)) for the determination of 2,4,6-trichlorophenol (2,4,6-TCP). The assays are based on the competition between the analyte and an analyte derivative labelled with the enzyme β-galactosidase, for an anti-TCP antibody, followed by the injection of the mixture at equilibrium into a flow stream, where separation between the fractions bound and unbound to the antibody is performed in a glass capillary containing immobilized protein A. The antibody-tracer fraction retained inside the protein A capillary was measured by injection of 4-aminophenyl-β-D-galactoside (4-APG), followed by amperometric detection of the enzymatically generated 4-aminophenol (4-AP), leading to a negative correlation between the signal and the analyte concentration. The two immunoassay formats were compared in terms of sensitivity and speed, giving IC50 values of 1.41±0.03 and 1.64±0.07 µg L-1, detection limits of 0.2 and 0.4 µg L-1, and sample throughputs of 6 and 4 h-1 for the CFIIA and CSIIA system, respectively. The influence of different interfering chlorophenolic compounds in the assay was minor, with only one exception (i.e. 2,4-dichlorophenol). In addition, different water matrices were tested (surface, tap, and rain water), showing that the matrix influence was negligible, except for rainwater, which resulted in a 30% increase in sensitivity. As a conclusion, the assay is suitable for the fast screening of TCP present at low concentration levels in water samples.
2,4,6-Trichlorophenol Amperometry Immunoassay Interferences

"Versatility Of The Titanium(IV)–Porphyrin Reagent For Determining Hydrogen Peroxide"
Bull. Chem. Soc. Jpn. 2003 Volume 76, Issue 10 Pages 1873-1888
Kiyoko Takamura and Chiyo Matsubara

Abstract: Hydrogen peroxide has been an important analyte in many fields for many years. The Ti-TPyP reagent, i.e., an acidic aqueous solution of oxo[5,10,15,20-tetra(4-pyridyl)porphyrinato]titanium(IV) complex, was developed as a highly sensitive spectrophotometric reagent for determining traces of hydrogen peroxide. Following the addition of hydrogen peroxide to the reagent, the absorbance at 432 nm decreased and a new peak appeared at 450 nm (the Soret band) accompanied by the consumption of the complex and the formation of its monoperoxo complex, respectively. The degrees of the absorbance changes were found to be proportional to the hydrogen peroxide concentration with the apparent molar absorptivities of 1.9 x 105 (432 nm) and 1.1 x 105 (450 nm) M-;1 cm-;1 (1 M = 1 mol dm-;3). Both values are much larger than those obtained by the conventional analysis methods. Based on these facts, the determination of hydrogen peroxide was made by a batch method and a flow injection analysis (FIA) method with the detection limits of 25 pmol and 0.5 pmol per test, respectively. In this account, the Ti-TPyP reagent is assessed for determining hydrogen peroxide in rainwater and in the atmosphere, and for determining several components in foods and biofluids mediated by appropriate oxidase enzymes, to demonstrate its potential for a broad range of applications.
Hydrogen peroxide Spectrophotometry Optimization Method comparison