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

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Classification: Environmental -> water -> river

Citations 234

"Sensitive And Rapid Flow Injection Analysis Of Sulfonylurea Herbicides In Water With Micellar-enhanced Photochemically Induced Fluorescence Detection"
Anal. Chim. Acta 1999 Volume 392, Issue 2-3 Pages 255-264
Atanasse Coly and Jean-Jacques Aaron

Abstract: A flow injection analysis (FIA) system, combined with micellar-enhanced photochemically induced fluorescence (MEPIF) detection is developed for the sensitive and rapid determination of four sulfonylurea herbicides including chlorsulfuron, metsulfuron methyl, 3-rimsulfuron and sulfometuron methyl in water. The use of micellar solutions of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium chloride (CTAC) as mobile phase provides improved analytical conditions. The FIA manifold parameters, viz, injection volume, flow rate and reactor length were optimized. Calibration plots were linear over 1-2 orders of magnitude. Relative standard deviation ranged from 1.5% to 3.7%. Limits of detection (LOD) were comprised between 0.1 and 1 ng mL-1 according to the compound. The sample throughput was between 56 and 80 h-1. Examples of application to the analysis of these herbicides in spiked river water are given. The mean recoveries ranged from 90% to 106%.
Chlorsulfuron Metsulfuron methyl 3-Rimsulfuron Sulfometuron methyl Fluorescence Fluorescence Reactor Micelle

"Usefulness Of Micellar Media For The Quantitative Analysis Of Phenylurea Herbicides In Water By Photochemically-induced Fluorescence"
Analusis 1999 Volume 27, Issue 10 Pages 857-863
A. Bautista, J. -J. Aaron, M. C. Mahedero and A. Muñoz de la Peña

Abstract: UV irradiation of four non-fluorescent phenylurea herbicides including linuron, diuron, isoproturon and neburon is shown to yield fluorescent photoproducts. The photochemically-induced fluorescence (PIF) properties of these herbicides in several media (water. 2-propanol and their mixtures) and aqueous micellar solutions of sodium dodecyl sulfate (SDS), and cetyltrimethylammonium chloride (CTAC) are reported. The use of micellar media enhances significantly the PIF signal relative to an aqueous solution. A PIF method is developed for the determination of the four herbicides under study, with linear dynamic ranges over about one order of magnitude, and limits of detection (LOD) between 410 and 640 ng mL-1, according to the compound. Applications to the analysis of tap water and river water samples yield satisfactory recoveries (86-115%).
Diuron Herbicides, phenylurea Isoproturon Linuron Neburon Fluorescence Micelle

"Determination Of Traces Of Nitrite And Nitrate In Water By Solid Phase Spectrophotometry"
Anal. Chim. Acta 2000 Volume 410, Issue 1-2 Pages 185-192
M. N. Abbas and G. A. Mostafa

Abstract: A simple and sensitive method for the determination of nitrite and nitrate in water using solid phase spectrophotometry is described. The method utilizes the quantitative and rapid sorption of the dye formed from nitrite, using the Griess reaction, into a thin layer of polyurethane foam (PUF) where a pre-concentration factor of >140 has been achieved. Nitrate is pre-reduced using a cadmium reductor before applying the Griess reaction. The direct spectrophotometric measurement of the dye enriched in the solid foam phase has allowed the detection of as little as 5 and 40 ng mL-1 nitrite and nitrate, respectively. Optimization of the parameters affecting the quantitative formation and sorption of the dye into PUF has been considered. Analysis of natural water samples has been performed.
Nitrate Nitrite Spectrophotometry Polyurethane foam Preconcentration Extraction Solid phase detection

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

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

"A Comparison Between ICP-MS And AFS Detection For Arsenic Speciation In Environmental Samples"
Talanta 2000 Volume 51, Issue 2 Pages 257-268
Jose Luis G&oacute;mez-Ariza, Daniel S&aacute;nchez-Rodas, Inmaculada Gir&aacute;ldez and Emilio Morales

Abstract: Performances of two atomic detectors, Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) arid Atomic Fluorescence Spectrometry (AFS) have been compared for arsenic speciation in environmental samples. Instrumental couplings, based on the use of high performance liquid chromatography (HPLIC), hydride generation (HG), and the two atomic detectors were used for the speciation of arsenite, arsenate, dimethylarsinic acid and monomethylarsonic acid. Optionally, arsenobetaine was also determined using on-line ultraviolet (UV) photooxidation. The detection limits ranging from 0.1 to 0.3 µg L-1 (as As) and the precision > 10% RSD obtained with HPLC-(UV)-HG-AFS were comparable with those obtained with HPLC-(UV)-HG-ICP-MS. Both instrumental coupling were applied to the NRCC-TORT-1 and several environmental samples, such as seawater, freshwater, sediments, bivalves and bird eggs, taken from two areas with different degrees of pollution. No influence of the sample matrix was observed on the results using external calibration and standard additions met:hods, for both coupled techniques.
Arsenate ion Arsenite Arsenoβine Dimethylarsinic acid monomethylarsonic acid Fluorescence Mass spectrometry Sample preparation HPLC Speciation Extraction Method comparison Reference material Interferences Standard additions calibration Optimization

"Sensitive Flow Injection Colorimetry Of Nitrite By Catalytic Coupling Of N-phenyl-p-phenylenediamine With N,N-dimethylaniline"
Talanta 1999 Volume 48, Issue 1 Pages 103-107
Ryoichi Kadowaki, Shigenori Nakano and Takuji Kawashima

Abstract: A rapid, sensitive and selective flow injection colorimetry method is proposed for the determination of trace amounts of nitrite. It is based on the nitrites catalytic effect on the oxidative coupling of N-phenyl-p-phenylenediamine with N,N-dimethylaniline to produce a green dye (lambda(max) = 735 nm) in the presence of bromate. The change in absorbances of the dye were monitored in continuous flow mode. Linear calibration curves were obtained for the nitrite concentration range 2.0-100 ng mL-1. The proposed method had a low detection limit (0.6 ng ml-1) and high sample throughput (approximately 30 samples h-1). The RSD for 10 and 50 ng mL-1 nitrite were 2.4 and 1.3% (n = 10). respectively. The method has been successfully applied to the determination of nitrite in river water samples.
Nitrite Spectrophotometry Catalysis Optimization Interferences Method comparison

"Lead Determination With On-line Enrichment System"
Water Res. 2000 Volume 34, Issue 17 Pages 4215-4219
Krystyna Pyrzynska and Mihaela Cheregi

Abstract: The flow injection pre-concentration system with a cellulose sorbent was developed to determine trace; mounts of lead. The metal was pre-concentrated on a microcolumn packed with Cellex P, cellulose sorbent with phosphonic acid groups, and eluted with nitric acid into the nebuliser-burner system of atomic absorption spectrometer. An enrichment factor of 47-197, equivalent of 5.1-25.5 mL of sample, was achieved by using time-based system. The detection limit (3 delta) for 1 min pre-concentration time was 1.8 µg L-1 and precision (at 10 µg L-1 level) was 7.8% (RSD). The method was applied to the determination of lead in natural water samples.
Lead Spectrophotometry Preconcentration Optimization Method comparison Cellulose Cellex Column

"A Flow System Exploiting Multicommutation For Speciation Of Inorganic Nitrogen In Waters"
Anal. Chim. Acta 2000 Volume 409, Issue 1-2 Pages 227-235
F&aacute;bio R. P. Rocha and Boaventura F. Reis

Abstract: A flow system for the speciation of inorganic nitrogen in waters is described. Multicommutation and binary sampling approaches are exploited to perform the sequential determination of nitrate, nitrite and ammonium without changing the manifold. Gravitational flow of solutions is employed in the sampling steps in order to avoid the effect of pulsation of the peristaltic pump on precision. A homemade photometer based on a dual-color (red/green) LED and a photodiode is employed to detect the reaction products. The repeatability was estimated as 0.32, 0.42 and 0.72% for nitrite, nitrate, and ammonium, respectively. A sampling rate of 60 determinations per hour was attained and the reagent consumption was reduced to 25% (ammonium) and 45% (nitrate and nitrite) relatively to conventional flow injection analysis (FIA) procedures. Detection limits of 5 µg L-1 NO2-, 15 µg L-1 NO3-, and 25 µg L-1 NH4+ were estimated at the 99.7% confidence level. Results for river water samples agreed with those obtained by conventional FIA or ion chromatography at the 95% confidence level.
Nitrate Nitrite Ammonia Spectrophotometry Multicommutation Speciation Photodiode Method comparison

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

Abstract: The paper describes a method of flow injection analysis for the determination of the pesticide Naptalam based on its hydrolysis, in an acidic medium, to 1-naphthylamine and the measurement of fluorescence due to this product in an alkaline medium. By direct injection of Naptalam in a carrier of HCl 1.0 M, subsequent heating at 100°C in the reactor and change of the pH with a flow of NH4OH 1.5 M, concentrations >3 x 10^-6 M can be analyzed. The sensitivity of the procedure is greatly increased by using online, a column (10 cm length x 0.3 cm i.d.) filled with a C-18 modified silica packing to retain a large volume of Naptalam. The injection of a very small volume of acetonitrile is enough to elute the pesticide, thus increasing the concentration in the sample zone to a great extent. The method has been successfully applied to the analysis of Naptalam, at the ppb level, in river-water samples.
Naptalam Fluorescence Preconcentration C18 Heated reaction Solid phase extraction

"Determination Of Sulfate In River Water By Flow Injection Analysis"
Anal. Chim. Acta 1982 Volume 134, Issue 1 Pages 353-358
Osamu Kondo, Haruo Miyata and Kyoji T&ocirc;ei

Abstract: Sulfate ion in river water is determined by flow injection analysis at a rate of 30 samples per hour; the sulfate contents are typically less than 30 ppm. The reagent solution contains dimethylsulfonazo-III, barium chloride, potassium nitrate and chloroacetate buffer in 70% (v/v) ethanol, and is saturated with barium sulfate. The aqueous carrier stream is also saturated with barium sulfate. The sample is filtered and treated with Amberlite IR120-B cation-exchanger before injection into the carrier stream, and the decoloration of the barium-dimethylsulfonazo-III complex by sulfate is measured at 662 nm. The calibration graph is linear over the range 0-30 g mL-1 for sulfate in water.
Sulfate Ion exchange Spectrophotometry Theory

"Spectrophotometric Determination Of Aluminum In River Water With Bromopyrogallol Red And N-tetradecyltrimethylammonium Bromide By Flow Injection Analysis"
Anal. Chim. Acta 1982 Volume 140, Issue 1 Pages 313-317
C. Wyganowski, S. Motomizu and K. T&ocirc;e&icirc;

Abstract: In the proposed flow injection system, the reagent solution contains bromopyrogallol red, n-tetradecyltrimethylammonium bromide and hexamine in 60% ethanolic solution, and the carrier solution contains acetate buffer, 1,10-phenanthroline and hydroxylammonium chloride. Sample solutions (160 µL) acidified by sulfuric acid are injected and the peak absorbance at 623 nm is recorded. The detection limit is about 0.001 ppm and calibration plots are linear for the ranges 0-0.3 and 0-0.1 ppm aluminum.
Aluminum Spectrophotometry

"Potentiometric Flow Injection Determination Of Chloride"
Anal. Chim. Acta 1983 Volume 151, Issue 1 Pages 77-84
Marek Trojanowicz and Wojciech Matuszewski

Abstract: A Cl--selective electrode was prepared from a silver - AgCl electrode by surface oxidation of the silver in 0.5 M FeCl3. A double-junction SCE with a 1 M NH4NO3 bridge was the reference electrode. In the low concentration. range (15 to 50 µM), the Cl- concentration. was directly proportional to the electrode potential. In the Nernstian response region, the dispersion in the flow system influenced the lower limit of the rectilinear calibration range whereas in the sub-Nernstian region it influenced the slope of the electrode response curve. The method was applied in the determination of Cl- in river water. The results agreed well with those obtained by titration, with standard deviations of ~1.5 mg L-1 at the level of 40 mg l-1
Chloride Electrode Potentiometry Dispersion

"Comparison Of Titrimetric, Spectrophotometric And Ion-chromatographic Methods For Determination Of Hydrogen Carbonate In Drinking And Mineral Waters"
Anal. Chim. Acta 1984 Volume 162, Issue 1 Pages 451-455
Da-renk Yan, B. R&ouml;ssner and G. Schwedt

Abstract: In the titrimetric method the sample was titrated with 0.02 M HCl in the presence of an indicator or by use of a pH meter (end-point at pH 4.4). In the spectrophotometric method, a series of standard solution of NaHCO3, containing KH2PO4 and methyl red, and each one diluted to 25 mL with CO2-free water, was prepared for absorbance measurements at 520 or 570 nm. Analysis of the samples was effected similarly, but 20 mL of natural water (<100 mg L-1 of HCO3-) or 0.5 to 5 mL of mineral water (100 to 1000 mg L-1 of HCO3-) was used in place of NaHCO3. A continuous-flow procedure based on the spectrophotometric method was also investigated, in which the detection limit was 0.75 mg l-1, and >60 samples per hour could be analyzed. For the ion-chromatographic method, a HPLC system was used, but only for a few analyzes of tap-water. Results for tap-water, river water and mineral water samples were in good agreement for each method.
Bicarbonate Spectrophotometry Method comparison

"Flow Injection Amperometric Determination Of Chlorine At A Gold Electrode"
Anal. Chim. Acta 1985 Volume 178, Issue 2 Pages 319-323
Alexandra N. Tsaousis and Calvin O. Huber

Abstract: Samples (30 µL) were injected into a mobile phase electrolyte (1.0 mL min-1) of 0.05 M phosphate at pH 7.4. The flow-through thin-layer amperometric detector incorporated a circular gold electrode (3 mm diameter) which was pre-treated at +1.3 V (vs. the SCE) for 40 s followed by a pre-injection delay of 20 s before use at +0.2 V. Peak current over a falling baseline was measured. The rectilinear range extended down to 0.4 µM for chloramine and 0.2 µM for hypochlorite. Each determination takes <1.5 min. Monochlorinated glycine is active whereas chlorinated cyanurates show no response. The method is applied to the determination of chlorine and chloramine in river water.
Chlorine Chloramines Hypochlorite Amperometry Electrode

"Development Of A Selective Post-column Detector For Phenols Separated By High Performance Liquid Chromatography"
Anal. Chim. Acta 1987 Volume 192, Issue 2 Pages 277-287
S. K. Ratanathanawongs and S. R. Crouch

Abstract: Samples are injected into the HPLC system for separation followed by UV detection at 254 nm. The column eluate is passed to an air-segmented continuous-flow system and mixed with diazotized sulfanilic acid, and the azo-derivatives are detected at 450 nm. The aqueous reaction system was compatible with reversed-phase mobile phases. Band-broadening (caused by the post-column reactor) was observed, following optimization, to be between 5 and 20%. A rectilinear response from 0.071 to 14 µg mL-1 of phenol was obtained. The system was demonstrated by the analysis of river water containing phenol, aniline, o-cresol and 3,5-xylenol and of residual fuel oil fractions containing phenol and o-cresol.
Phenol Aniline 2-Cresol Xylenol HPLC Spectrophotometry Optimization Post-column derivatization

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

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

"Automated Spectrophotometric Field Monitor For Water Quality Parameters. Determination Of Nitrate"
Anal. Chim. Acta 1987 Volume 200, Issue 1 Pages 523-531
J. Richard Clinch and Paul J. Worsfold, Harry Casey

Abstract: The design and operation are described of an automated spectrophotometric field monitor based on flow injection analysis for the determination of NO3- in river water. The sample (30 µL) is injected into aqueous 1% NH4Cl as carrier stream (0.7 mL min-1); the solution then passes through a 40-mm reductor column of copperized Cd, and is mixed with N-1-naphthylethylenediamine dihydrochloride (0.25 g l-1) - sulfanilamide (12.5 g l-1) solution in 10% H3PO4. The absorbance of the resulting solution is monitored by a photometric detector with a green light-emitting diode. Response was rectilinear up to 12 mg L-1 of nitrate-N and the detection limit was 24 µg l-1. The coefficient of variation ranged from 0.0 to 0.7%. Results agreed well with those from two other spectrophotometric methods.
Nitrate Spectrophotometry Light emitting diode Method comparison Reduction column Portable

"Flow Constant-current Stripping Analysis For Antimony(III) And Antimony(V) With Gold Fiber Working Electrodes. Application To Natural Waters"
Anal. Chim. Acta 1987 Volume 202, Issue 1 Pages 123-129
Huang Huiliang, Daniel Jagner and Lars Renman

Abstract: To determine Sb(III), a sample was made 20 µM in KI (to mask Bi(III)) and 0.1 M in HCl and the solution was passed at 1 mL min-1 through a flow cell system containing a 10 µm gold-fiber working electrode, a Ag - AgCl reference electrode and a platinum counter electrode (cf. Anal. Abstr., 1987, 49, 10J160); electrolysis was carried out for 10 min at -0.4 V. Then, either 2 M HCl or 4 M HCl - 4 M CaCl2 was passed through the cell and stripping was effected at a constant current of 0.5 µA. To determine the sum of Sb(III) and Sb(V) (and hence Sb(V) by difference), electrolysis was carried out in 20 µM-KI - 4 M HCl. The method of standard additions was used for evaluation. Results obtained for Sb(V) in river water reference sample SLRS-1 were in excellent agreement with the certified value.
Antimony(3+) Antimony(5+) Amperometry Electrode Reference material Standard additions calibration

"Continuous-flow System For The Determination Of Cobalt In Sea And River Water. Inline Preconcentration/separation Coupled With Catalytic Determination"
Anal. Chim. Acta 1988 Volume 207, Issue 1-2 Pages 331-336
Takeshi Yamane and Keiko Watanabe, Horacio A. Mottola

Abstract: Water (50 ml), acidified to 0.01 M with HNO3, was mixed with 0.2 M Na acetate carrier solution and aqueous 0.1 M NH3 to give pH 6.1 to 6.3. The solution was fed at 2 mL min-1 through a pre-concentration. column (3 cm x 4 mm) of silica-immobilized quinolin-8-ol (80 to 120 mesh). The Co and other retained metal ions were eluted with 0.5 M HCl and the eluate was passed to a separation column (7 cm x 4 mm) of Hitachi Custom, a strongly acidic cation exchanger (15.5 µm). The mobile phase was 0.2 M Na tartrate - 6 mM tartaric acid (pH 5.1). This step prevented interference from species such as Fe(III) and Mn(II). The eluted Co catalyzed the reaction of H2O2 and protocatechuic acid, and the absorbance was measured at 480 nm. The detection limit was 5 pg mL-1 of Co. The calibration graphs were rectilinear up to 0.08 ng mL-1. The method was applied to coastal seawater and surface river water.
Cobalt Spectrophotometry Catalysis Interferences Preconcentration 8-Hydroxyquinoline Silica

"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

"Spectrometric Determination Of Phosphorus In River Water Based On The Reaction Of Vanado-molydophosphate With Malachite Green"
Anal. Chim. Acta 1988 Volume 211, Issue 1 Pages 119-127
Shoji Motomizu, Mitsuko Oshima and Atsushi Hirashima

Abstract: The formation of an ion-associate between vanadomolybdophosphate and malachite green in aqueous acidic solution (0.5 M sulfuric acid) enables trace amounts (0-1 x 10^-5M) of phosphate to be determined. The molar absorptivity is 1.05 x 10^5 l mol-1 cm-1 at 620 nm. The complex was stabilized in solution by adding poly (vinyl alcohol). Other ions generally found in river waters did not interfere. Interference by silicate is less than that found in the corresponding malachite green molybdophosphate procedure; interference of arsenate is avoided by reduction with thiosulfate. The method is applied to the determination of µg L-1 amounts of phosphorus in river water; the results obtained were in good agreement with those obtained by an extraction-spectrophotometric method with malachite green.
Phosphorus Spectrophotometry

"Flow Injection Determination Of Sodium And Potassium By Separation On A Silica Column And Extraction-spectrophotometry With Benzo-18-crown-6 And Tetrabromophenolphtalein Ethyl Ester"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 289-298
Shoji Motomizu and Minoru Onoda

Abstract: A sample was injected into the carrier stream (H2O) and mixed with the reagent stream containing crown ether and Li acetate before passing to a column (30 cm x 1 mm) of C-200 silica gel (100 to 200 mesh). The percolate was mixed with reagent solution (EDTA - LiOH) and then extractant (K salt of tetrabromophenolphthalein ethyl ester) in a segmentor before passing through an extraction coil (2 m x 0.5 mm) to a phase separator containing a porous membrane. The absorbance of the organic phase was measured at 620 nm. The flow rate of each of the streams was 0.8 mL min-1. Of the three crown ethers studied, the best results were achieved with benzo-18-crown-6. Calibration graphs were rectilinear up to 2 and 0.2 mM for Na and K, respectively. Results for determination of Na and K in river water agreed with those obtained by AAS. The method was also applied to the analysis of tap-water.
Sodium Potassium HPLC Spectrophotometry Sample preparation Extraction Crown ether Method comparison Phase separator Organic phase detection Silica gel

"Flow-through PH-ISFET As Detector In The Determination Of Ammonia"
Anal. Chim. Acta 1990 Volume 231, Issue 1 Pages 53-58
S. Alegret, J. Alonso, J. Bartroli and M. del Valle, N. Jaffrezic-Renault and Y. Duvault-Herrera

Abstract: The alumina pH-ISFET with rear-side contacts described by Van den Vlekkert et al. (Sens. Actuators, 1988, 14, 165) was incorporated in a gas-dialysis flow injection system, which is illustrated schematically. Ammonium ions are converted into NH3, which diffuses through a microporous hydrophobic membrane (Millipore GVHP 0950) into a stream of 2 mM NH4Cl (I adjusted to 4 mM with K2SO4) to form a buffer solution, the pH of which is monitored by the ISFET. The range of rectilinear response was 0.1 to 10 mM, the detection limit was 0.05 mM, and the within-day coefficient of variation (n = 12) at 0.7 mM NH4Cl was 1.03%. The system was applied to river water.
Ammonia Field effect transistor Electrode Electrode Dialysis Millipore Gas diffusion Detection limit Microporous membrane Buffer Hydrophobic membrane

"Formation Kinetics Of The Pink Azo Dye In The Determination Of Nitrite In Natural Waters"
Anal. Chim. Acta 1990 Volume 232, Issue 2 Pages 345-350
Su-Cheng Pai and Chung-Cheng Yang, John P. Riley

Abstract: The kinetics of the reactions for the formation of the pink azo dye in the determination of nitrate in both fresh water and seawater was studied at different acidities, temperatures, and concentrations of N-1-naphthylethylenediamine (NED). It was found that the reaction is considerably faster in seawater than in fresh water, and that increase in the acidity slightly increases the molar absorptivity. A concentration of NED (4.29 times 10^-6 M) between the extremes described in the literature and 4.2 times 10^-3 M sulfanilamide are recommended for both manual determination and flow injection analysis with respect to rapid reaction and a low reagent blank.
Nitrite Spectrophotometry Optimization Kinetic

"Determination Of Nitrate With A Flow Injection System Combining Square-wave Polarographic Detection With Online Deaeration"
Anal. Chim. Acta 1990 Volume 234, Issue 2 Pages 475-478
Mouna Noufi, Ch. Yarnitzky and Magda Ariel

Abstract: The catalytic reaction between NO3- and UO22+ is used to provide a simple, rapid, sensitive and accurate method for determining NO3- in river and potable water. The carrier (H2O) and reagent (0.2 M KCl - 0.02 M HCl - 0.2 mM - UO22+) streams are pumped (0.6 mL min-1) into a coil (30 cm x 0.5 mm) and 200 µL of aqueous NO3- is injected. A diagram of the apparatus is given. Voltammetry is performed with reference to an Ag - AgCl (3 M KCl) electrode, delay 4 s, scan rate 100 mV s-1 and a potential range of -0.6 to -1.1 V. The calibration graph is rectilinear for 5 to 60 µM-NO3-1, with a detection limit of 2 µM. The effect of anions on the reduction is studied.
Nitrate Polarography Electrode Voltammetry Catalysis Apparatus Calibration Detection limit

"Online Continuous-flow Extraction System In Liquid Chromatography With Ultraviolet And Mass Spectrometric Detection For The Determination Of Selected Organic Pollutants"
Anal. Chim. Acta 1990 Volume 234, Issue 1 Pages 119-126
A. Farran, J. L. Cortina and J. de Pablo, D. Barcel&oacute;

Abstract: A system is described which allows UV detection and MS characterization of ng amounts of pesticides in water. It involves completely continuous-flow analysis, with extraction with heptane, a PTFE membrane separator, separation on a column of Spherisorb ODS, and detection at 220 nm and by MS. Extraction varied from 60% (for organophosphorus pesticides and the degradation product 2,4,5-trichlorophenol) to 100% for chlorophenoxy acids, except for the degradation product 4-nitrophenol (10%). The limit of detection was 200 to 400 pg with UV detection. Tetrachlorvinphos was determined in a spiked river water at 1 mg L-1 by MS with selected-ion monitoring.
Pesticides Tetrachlorvinphos 2,4,5-Trichlorophenol LC Mass spectrometry Sample preparation Small sample Column Detection limit Extraction Phase separator Teflon membrane

"Determination Of Nanoequivalent Amounts Of Organic Halogens By Sample Combustion-flow Injection Conductimetry With Online Preconcentration"
Anal. Chim. Acta 1990 Volume 241, Issue 1 Pages 71-82
I. G&aacute;cs and K. Payer

Abstract: The sample was heated at 950°C in a stream of O2 and the decomposition products containing halogens were absorbed in a capillary denuder tube coated with an aqueous solution of a hydrazine monohydrohalide. The hydrohalic acid formed in the liquid film was eluted with a solution of the absorbant to a conductivity microdetector where the change in specific conductance due to the acid was rectilinearly related to the halogen content. The method was tested with 14 compounds and was applied to the analysis of river and drinking water and to industrial atmospheres. The limit of detection for the volatile organic halogen content in water was 0.01 µg L-1 and 0.2 µg m-3 for the total organic halogen content in air. For 3 to 100 nanoequivalents of Cl, the precision (95% confidence limits) (n = 5) was 5%.
Organic, halogenated Conductometry Detector Detection limit Preconcentration

"Spectrophotometric Method For The Determination Of Ionic Surfactants By Flow Injection Analysis With Acidic Dyes"
Anal. Chim. Acta 1991 Volume 246, Issue 2 Pages 333-339
Koichi Yamamoto, Shoji Motomizu

Abstract: Two systems are described for the determination of cationic and anionic surfactants, respectively. In the former system, the reagent stream (0.37 mL min-1) consists of 25 µM-bromocesol purple in 30 mM phosphate buffer (pH 8.1); a portion (200 µL) of the sample cationic surfactant (e.g., benzyldimethyltetradecylammonium chloride) solution is injected into a carrier stream (0.37 mL min-1) of water. After reaction in the reaction coil (200 cm x 0.5 mm), the resulting decrease in absorbance at 588 nm is measured and related to the surfactant concentration.; calibration graphs are rectilinear up to 50 µM. No interference was observed from ions commonly present in river water. In the second system, anionic surfactants are determined by a similar method, except that the carrier solution is replaced by 40 µM-benzylhexadecyldimethylammonium chloride; the method is based on reaction between the anionic surfactant (analyte) and the cationic surfactant in the carrier stream, which results in a depression of the decrease in absorbance at 588 nm.
Surfactants, anionic Surfactants, cationic Spectrophotometry Buffer Interferences

"In-flow Speciation Of Copper, Zinc, Lead And Cadmium In Fresh Waters By Differential-pulse Anodic Stripping Voltammetry. 1. Optimization Of Filtration And Enrichment Steps"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 323-334
W. Martinotti* and G. Queirazza, F. Realini, G. Ciceri

Abstract: An automatic system for the in-situ determination of dissolved Cu, Zn, Pb, and Cd in fresh waters, composed of a filtration unit, a separation and enrichment unit, and an electrochemical unit for differential-pulse anodic stripping voltammetry, was investigated. The filtration and enrichment units were designed to establish the most effective experimental conditions for the measurement of the metal concentrations at environmental levels. The system was built for installation in a buoy equipped with a facility for radiotransmission of the data obtained.
Copper Zinc Lead Cadmium Voltammetry Remote instrument Automation Optimization Filtration Speciation

"Continuous-flow Determination Of Phosphate Using A Lead-ion-selective Electrode"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 411-417
Hirokazu Hara* and Suzuka Kusu

Abstract: An Orion 94-82A solid-state Pb2+-selective electrode was used in conjunction with an Orion 90-02-00 double-junction reference electrode for detection in the described continuous-flow system. The phosphate-containing solution was introduced into a solution of 35 µM-Pb(NO3)2 in 35 mM Na2B4O7 - 55 mM acetic acid buffer (pH 8.1), and the associated decrease in the free Pb2+ concentration. (due to precipitation of lead phosphate) was monitored. Four standard solutions were used for calibration. The detection limit was 1 µM-phosphate. In the determination of phosphate in river water, the most significant interfering species were Ca, Cl- and metasilicate.
Phosphate Electrode Interferences Indirect

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

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

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

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

"Time-based And Volume-based Sampling For Flow Injection Online Sorbent-extraction Graphite-furnace Atomic Absorption Spectrometry"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 477-487
Bernhard Welz*, Xuefeng Yin and Michael Sperling

Abstract: Separation of the analyte from the sample matrix, and its pre-concentration, were achieved by use of a Perkin-Elmer model FIAS-200 flow injection accessory having its sample loop replaced by a conical micro-column (Eppendorf pipette tip) packed with 15 µL of RP-C18 solid-phase sorbent. The flow injection manifold was connected to the sample-introduction capillary of a Perkin-Elmer model Zeeman/3030 AAS instrument equipped with an HGA-600 graphite tube furnace and an AS-60 furnace autosampler. Details and diagrams are given of the sequence of operations for pre-concentration, involving volume-based sub-sampling; the system was more sensitive than one involving time-based sub-sampling. The system was applied in the determination of Cd, Cu, Pb and Ni. The acidified sample was mixed with a pre-purified 0.05% solution of Na diethyldithiocarbamate (I) in 0.06 M NH3 - 0.03 M acetic acid buffer (pH 9), and the metal - I complex was adsorbed on the micro-column. The column was then washed in the reverse direction with 0.02% (v/v) HNO3 before elution of the complex with ethanol and transfer of only 40 µL of the eluate to the graphite tube; furnace operating parameters are specified. With 60-s pre-concentration. of the analyte, the detection limits for Cd, Cu, Ni and Pb were 0.6, 8.5, 21 and 4 ng l-1, respectively. The method was used to determine the cited metals in standard reference seawater (open-ocean and coastal), estuarine water and river water; results agreed well with reference values. Flow injection online pre-concentration. systems for graphite furnace atomic absorption spectrometry are complicated by the low eluate volume of typically less than 50 µL which can be accommodated in a graphite tube or on a graphite platform. Even when a column with an extra small capacity of 15 µL was used, it was found impossible to elute the sorbed analyte completely with an eluate volume that was compatible with the capacity of the graphite furnace. Two approaches for introducing only the most concentrated fraction of the eluate into the graphite tube while discarding the rest were investigated and compared: controlling the time interval for collection and introduction of the eluate fraction into the furnace tube (time-based sampling), and collection of the eluate fraction of interest in thin tubing of fixed volume, followed by introduction of this fraction into the tube using a low flow of air (volume-based sampling). Cadmium, copper, lead and nickel were the analyte elements investigated. A 15-30% greater enhancement factor was obtained for volume-based sampling because dispersion was interrupted during sample injection by air segmentation. The short- and long-term reproducibility were also better for volume-based sampling because variations in the pump tubing had no influence on the eluate volume introduced. These combined effects resulted in an improvement in detection limits of the four elements by factors of 1.3-2.0. Sample throughput (23 h-1), sample consumption (3 mL min-1) and reagent consumption were the same for both approaches. There were no significant differences in the accuracy and precision of the two techniques in the anal. of seawater, estuarine water and river water standard reference materials.
Cadmium Copper Lead Nickel Spectrophotometry Sample preparation Matrix removal Preconcentration Timed injection Reference material FIAS-200 Reagent consumption Solid phase extraction

"Chemical Oxygen Demand Determination In Well And River Waters By Flow Injection Analysis Using A Microwave Oven During The Oxidation Step"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 295-299
M. L. Balconi, M. Borgarello and R. Ferraroli*, F. Realini

Abstract: The sample (0.25 ml) is injected into water as carrier and, after mixing, the stream is treated with oxidizing solution prepared by adding dropwise, with vigorous stirring, 10 mL of aqueous 12% K2Cr2O7 to 300 mL of concentrated H2SO4 and diluting the cooled solution to 1 l with concentrated H2SO4. The resulting solution passes through a reaction coil (10 m) enclosed by a microwave oven operated at 180 W and then through a cooling coil and a de-bubbler before absorbance measurement at 445 nm. Under optimum conditions (described), the calibration graph is rectilinear for COD up to 100 mg l-1, and the detection limit is 1.5 mg l-1. The coefficient of variation was 2.1% (n = 20) at 40 mg l-1. Results obtained on well, river and canal water, sewage and food industry waste agreed with those by a standard method. A flow injection method based on the use of a microwave oven to maximize the rate of the oxidation step is described. The flow system consists of 2 lines (water as carrier and K dichromate-H2SO4 mixture as reagent), 3 coils, of which the intermediate one (wound around a special strong microwave absorber support) acts as reaction coil, a membrane degassing unit, and a spectrophotometric detector. Optimal parameters includes the oven capacity at 180 W, application range in 0-100 mg/L COD, relative standard deviation 2.12% at 40 mg/L COD, and detection limit 1.5 mg/L COD. Preliminary applications were made to well water, river water (with low COD levels), and wastewaters. The results obtained are in good agreement with those given by the manual reference method.
Chemical oxygen demand Spectrophotometry Microwave Method comparison Optimization Standard method

"Indirect Spectrophotometric Determination Of Potassium Ion In Water Based On The Precipitation With Tetraphenylborate Ion And A Crown Ether Using Flow Injection"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 225-231
Shoji Motomizu*, Ko Yoshida and Kyoji T&ocirc;ei

Abstract: The sample is injected into a carrier stream of water, and this flow is mixed with one of 0.3 mM Na tetraphenylborate - 3 mM 18-crown-6 - 3 mM Li3EDTA - 20 µM-KCl (pH ~8.9) in a 5-m reaction coil maintained at constant temperature The mixture, which contains a ppt. of the K - 18-crown-6 - tetraphenylborate complex, is passed online through a resin filter and a filter paper, and the absorbance of residual tetraphenylborate in the filtrate is monitored at 274 or (for better sensitivity) 250 nm. With use of the described K+-saturated reagent, K in concentration. up to 10 mM can be determined. Calcium causes positive errors; interference from Fe can be overcome (details given). The method was successfully applied to tap-water and river water containing ~2.7 µM-K. Sample throughput was 30 h-1. A method is also described for determining the apparent solubility products of alkali-metal ions and tetraphenylborate in the presence of a crown ether. A precipitation reaction for alkali metal ions is proposed. Crown ether complexes of alkali metal ions were found to be less soluble than the alkali metal ions themselves in water when they form ion-association complexes with tetraphenylborate ion (TPB-) as a counter ion. The apparent solubility products (K'sp) of alkali metal ions were determined.; they were 10-100 times smaller than Ksp values of the ion-association complexes formed between alkali metal ion and TPB-. On the basis of the precipitation reaction, a flow injection method for the spectrophotometric determination of K in water samples is proposed. Samples were injected into a carrier stream, which merged with a reagent stream containing TPB, 18-crown-6, EDTA and saturated K+. The calibration graph was linear in the range 0-1 x 10^-4 M K+. The sample throughput was 30/h. The procedure was applicable to river and tap waters.
Potassium Spectrophotometry Indirect Crown ether Interferences Complexation Filter Precipitation

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

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

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

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

"Flow Injection Determination Of Thorium And Uranium After Online Ion-exchange Preconcentration On Dowex 50-X8"
Anal. Chim. Acta 1992 Volume 264, Issue 2 Pages 291-296
Jos&eacute; Luis P&eacute;rez Pav&oacute;n, Carmelo Garc&iacute;a Pinto, Estrella Rodr&iacute;guez Garc&iacute;a and Bernardo Moreno Cordero*

Abstract: Samples were pre-concentrated on a column (5 cm x 2 mm) of Dowex 50-X8 (20 to 50 mesh) included in the sample loop of the injection valve. A second valve contained a reducing column filled with Pb powder to reduce U(VI) to U(IV). Analysis was by flow injection analysis with spectrophotometric detection at 665 nm using Arsenazo III in 3.6 M HCl stabilized with Triton X-100. The calibration graphs were rectilinear up to 0.7 µM. Detection limits were ~1 µg L-1 and the coefficient of variation were ~2.5%. The method was tested with water samples (river and municipal) and recoveries were 92 to 102%, the method may be applied in the analysis of seawater. The pre-concentration of thorium and uranium on Dowex 50-X8 was studied as a method for the pre-concentration of these cations prior to their determination by flow injection with spectrophotometric detection using Arsenazo III in 3.6 M HCl stabilized with Triton X-100 as chromogenic reagent. The pre-concentration device is a minicolumn included in the sample loop of the injection valve. A second valve contains a reducing minicolumn filled with lead powder to reduce U(VI) to U(IV) before the confluence of the sample with the reagent stream. The method can be applied to samples containing 0.5-100 µg L-1 and was tested with different spiked water samples.
Thorium-232 Uranium Ion exchange Preconcentration Dowex Reduction column Triton X Chromogenic reagent Surfactant

"Simultaneous Determination Of Nitrate And Chloride By Means Of Flow Injection Amperometry At The Membrane-stabilized Water - Nitrobenzene Interface"
Anal. Chim. Acta 1992 Volume 268, Issue 2 Pages 285-292
Stefan Wilke*, Halka Franzke and Helmut M&uuml;ller

Abstract: Sample solution (16 µL) was injected into a carrier stream of water which merged with a supporting electrolyte of aqueous 10 mM Na2SO4; the flow rate of each stream was 1 mL min-1. The flow-through electrochemical detector cell (illustrated) contained a hydrophilic membrane filter of regenerated celullose (RC 58, Schleicher and Schuell) to stabilize the interface between the aqueous solution and an organic phase of 10 mM µ-nitridobis(triphenylphosphorus) dicarbollylcobaltate in nitrobenzene. Two Ag wires in the organic phase were used as reference and auxiliary electrodes while in the aqueous phase a Ag - AgCl electrode and the stainless-steel cell body were used. The electrodes were connected to a potentiostat (cf. Wilke, J. Electroanal. Chem., 1991, 301, 67), the filtered output from which was recorded. The results obtained for NO3- agreed well with those obtained by ion chromatography. The detector was ~11 times more sensitive to NO3- than to Cl-, and measurements of Cl- were thus only possible at high concentration. The technique was used to determine NO3- and Cl- in river water. An amperometric flow-through electrode based on ion transfer across the interface of 2 immiscible electrolyte solutions was developed. A hydrophilic cellulose membrane was utilized to stabilize the interface between the flowing aqueous solution and the stationary organic phase. The detector developed was applied in a flow injection system for the simultaneous determination of NO3- and Cl- in river water. Advantage was taken of the potential-dependent response of the amperometric detector and the sufficiently separated half-wave potentials of the transfer of NO3- and Cl- across the interface. The results obtained in the amperometric determination of NO3- agreed well with those from ion chromatography measurements. Because of the comparatively poor selectivity of the detector for Cl-, the amperometric determination can be used only when the Cl- concentration. of the sample is sufficiently high.
Nitrate Chloride Amperometry Electrode Organic phase detection Detector Apparatus Interferences Hydrophilic membrane Cellulose

"Flow Injection Sample Preparation For Organotin Speciation Analysis Of Water By Capillary Gas Chromatography - Microwave Induced Plasma Atomic-emission Spectrometry"
Anal. Chim. Acta 1993 Volume 278, Issue 1 Pages 99-113
Joanna Szpunar-obiska, Michiel Ceulemans, Ryszard obiski and Freddy C. Adams*

Abstract: A semi-automatic flow injection system is described for online sample preparation for the determination of mono-, di-, tributyl- and triphenyltin compounds in river water. The organotin compounds were extracted from 10^-50 mL of acidified water (pH 2) by adsorption onto a C18 micro-column, derivatized with sodium tetraethylborate and eluted with 250 µL of methanol containing tetrabutyltin as an internal standard. Portions of the eluate (25 µL) were analyzed by GC-AES with a temperature programmed cooled injection system which allowed the solvent to be vented off while the higher boiling point organotin compounds were transfered onto a column (25 m x 0.32 mm) coated with HP-1 (0.17 µm), operated with temperature programming from 45°C (held for 2 min) to 280°C at 20°C/min. Calibration graphs were rectilinear for 0-100 ng/l of the organotin compounds but there was a different response factor for each analyte due to the non-quantitative recovery of mono-substituted organotins. Detection limits were 0.1-0.17 ng/l with RSD (n = 5) of 4.3-9.2%.
Monobutyltin Dibutyltin Tributyltin Triphenyltin GC Spectrophotometry Sample preparation Column Extraction C18 Immobilized reagent Speciation

"Inter-laboratory Programme For The Quality Control Of Nitrate Determination In Fresh Water"
Anal. Chim. Acta 1993 Volume 283, Issue 1 Pages 600-606
Ph. Quevauviller, D. Van Renterghem and B. Griepink, M. Valcarcel*, M. D. Luque De Castrol and J. Cosano

Abstract: Certified reference materials for this analysis were prepared that contained 0.8, 8 or 53.8 mg/l of nitrate and had a hardness of ~10 degrees (French). Boiled water was sterilized and homogenized and passed through sterilized filters before the addition of the nitrate plus CaCl2 (91.7 mg/l), MgSO4 (123 mg/l), Na2CO3 (530 mg/l), and potassium hydrogen phthalate (5 mg/l) to introduce K+ and additional organic matter to simulate the presence of humic acids. These materials were stored in white glass ampoules at +20°C and remained stable for at least 3 months. The reference materials were analyzed for nitrate by a flow injection method based on the Griess reaction. The sample was injected into a carrier solution of NH4Cl, Na2B4O7 and EDTA, which was passed through a column of copperized Cd to reduce nitrate to nitrite. The resulting solution was introduced into a stream of sulfanilamide solution and the absorbance of the resulting azo-compound was monitored at 540 nm. Experimental set-up variations in the collaborating laboratories are detailed. For the 0.8 mg/l solution, the inter-laboratory RSD was high (8.7%) possibly because the non-linearity of the calibration graph had been disregarded.
Nitrate Nitrite Spectrophotometry Redox EDTA Reference material

"Online Trace Metal Ion Preconcentration In Ion Chromatography Using Carboxymethyl And Hydroxamate Dextran-coated Silicas"
Anal. Chim. Acta 1993 Volume 283, Issue 1 Pages 344-349
N. Ryan and J. D. Glennon*, D. Muller

Abstract: With use of a system incorporating a six-way valve, the metal ions were concentrated from aqueous solution adjusted with 0.5 M LiOH to pH 7 on a column (5 cm x 4 mm i.d.) of chelating adsorbent prepared by treating carboxymethyl dextran-coated silica with hydroxylamine [Srijaranai and Glennon, Analyst (London), 1990, 115, 627]. The metal ions were eluted on to a Dionex Analytical CS5 column for separation with 50 mM oxalic acid/95 mM LiOH of pH 4.8 as mobile phase (1 ml/min). A 0.3 mM 4-(2-pyridylazo)resorcinol solution (0.6 ml/min) was used for post-column derivatization and detection was at 520 nm. The method was used for the pre-concentration and determination of Pb, Cu, Cd, Co, Mn, Zn and Ni, and was applied to the determination of metals in domestic and laboratory tap-water and in river water. Limits of detection were 5-10 ng/ml of Cu, Mn, Co, Zn and Ni but >100 ng/ml for Pb and Cd.
Metals, trace Lead Copper Cadmium Cobalt Manganese Zinc Nickel HPIC Spectrophotometry Preconcentration Silica Post-column derivatization Immobilized reagent

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

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

"Fluorimetric Flow-through Sensor For Aluminum Speciation"
Anal. Chim. Acta 1994 Volume 295, Issue 1-2 Pages 59-65
P. Ca&ntilde;izares and M. D. Luque de Castro*

Abstract: Water was injected into a 0.1 M NaCl carrier stream (1 ml/min) and merged with a reagent stream (1 ml/min) containing 0.025% salicylaldehyde picolinylhydrazone in 40% ethanol and 0.5 M acetate buffer of pH 5-5.5. After passage through a PTFE mixing coil (400 cm x 0.5 mm i.d.), the complex formed was retained on a layer of Sep-Pak C18 in the flow cell for fluorescence measurement at 468 nm (excitation 382 nm). The complex was desorbed to waste by 2 M HCl. All forms of monomeric aluminum except the hydroxy species reacted. Total monomeric Al was determined by direct injection as described. Non-labile monomeric Al was determined by injection as above, but the carrier stream passed through a column (5 cm x 3 mm i.d.) of Amberlite IR-120 plus to retain cationic species, the anionic and neutral species then merging with the reagent. Acid-reactive Al was determined by adjusting the sample to pH 1, after 1 h readjusting to pH 6, then as for total monomeric Al. Acid-soluble Al and labile monomeric Al were calculated by difference. Calibration graphs for total monomeric Al were linear for 10^-200 ng/ml with a detection limit of 3 ng/ml. The method was used to study the effect of organic ligands (oxalate, citrate, acetylacetone) on the distribution of Al species. The results of analyzes of bottled, tap, spring, well and river waters are reported.
Aluminum Spectrophotometry Fluorescence Sensor Speciation Amberlite

"Comparison Of The Analytical Capabilities Of An Amperometric And An Optical Sensor For The Determination Of Nitrate In River And Well Water"
Anal. Chim. Acta 1994 Volume 299, Issue 1 Pages 81-90
Margaret A. Stanley, Joe Maxwell, Mairead Forrestal, Andrew P. Doherty, Brian D. MacCraith, Dermot Diamond and Johannes G. Vos

Abstract: The analysis of nitrate in water has been studied using novel amperometric and optical sensors. A flow-injection analysis system with amperometric detection has been developed in which nitrate is determined as nitrite after reduction in a cadmium column. The working electrode is glassy carbon modified with a crosslinked redox polymer. The linear range is 0.1 to 190 mg/l NO3-N (r>>0.999) and the limit of detection (LOD) is 50 µg/l NO3-N. A fiber optic sensor based on a dual wavelength absorption approach has also been developed. A signal at 210 nm where nitrate absorbs was referenced against a signal at 275 nm where nitrate does not absorb. Its linear range is from 0.4 to 30 mg/l NO3-N and its LOD is 400 µg/l NO3-N. These diverse methods have been applied to the analysis of the same river water samples and good correlations have been observed between the two measurement techniques and a standard ion chromatography method.
Nitrate Amperometry Sensor Method comparison

"Simultaneous Spectrophotometric Determination Of Nitrite And Nitrate In A Flow Injection System"
Anal. Chim. Acta 1995 Volume 302, Issue 2-3 Pages 283-287
Anatol Kojo* and Ewa Gorodkiewicz

Abstract: The FIA system incorporated a PTFE sample loop (50 cm x 1.5 mm i.d.) containing 29 cm of copperized Cd granules (<0.3 mm) through which the aqueous sample was introduced into 0.1 M NH4Cl as carrier. The resulting stream was merged with 60 mM sulfanilamide in 0.6 M HCl and then with 4 mM N-1-naphthylethylenediamine before passing to a flow cell for absorbance measurement at 510 nm. The reagent flow rate was 1.8 ml/min. As only part of the sample made contact with the reductant, the first portion of sample injected into the carrier stream contained nitrite and nitrate, whereas the second portion contained the original nitrite plus that from reduction of nitrate. The height of the shoulder on the recorded signal was proportional to nitrite and the maximum peak height was proportional to nitrite plus nitrate. Response was linear up to 35 and 10 mg/l of nitrate and nitrite, respectively, and at 4 and 1 mg/l, respectively, the corresponding RSD were 0.9 and 1.9%. The method showed good selectivity, and was applied to river water.
Nitrate Nitrite Spectrophotometry Simultaneous analysis Dual reaction zones

"New Enzyme Sensor For Sulfite Analysis In Sea And River Water Samples"
Anal. Chim. Acta 1995 Volume 305, Issue 1-3 Pages 32-41
L. Campanella*, P. Cipriani, T. M. Martini, M. P. Sammartino and M. Tomassetti

Abstract: A new sulfite oxidase enzyme electrode for sulfite analysis in sea and river water samples was developed. The biosensor was constructed by coupling an oxygen sensor to a nylon membrane with the enzyme chemically immobilized on it. Measurement on standard solutions and in matrices of environmental interest were carried out both under steady-state and flow conditions. The possibility of employing fructose as stabilizing agent for sulfite both for standard solutions and aqueous environmental samples was also studied.
Sulfite Sensor

"Simultaneous Flow Injection Determination Of Nitrate And Nitrite In Water By Gas-phase Chemiluminescence"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 308-312
Toyoaki Aoki* and Muneki Wakabayashi

Abstract: A flow injection procedure for the determination of nitrate (I) and nitrite (II) based on their reduction to NO followed by membrane phase separation and chemiluminescence detection was developed. Reductant was injected into a 0.5 M H2SO4 carrier stream (0.5 ml/min) which was merged with streams of sample solution (0.5 ml/min) and clean air (6 ml/min). After passing through a mixing coil (2 m x 1 mm i.d.), the mixture was propelled to the phase separator. The separator comprised an outer PTFE tube (4 mm i.d.) and an inner porous PTFE tube (2 mm i.d.). Air and NO permeated through the microporous membrane into a clean air stream and were swept to the chemiluminescent analyzer. (CL) where the chemiluminescence produced by with ozone was monitored. A Nafion permeation tube removed moisture. The reductant was 20% Ti(III) for the combined determination of I and II and 5% KI for the determination of II. The calibration graphs were linear for 5 µg N/l (I) and 3 µg N/l (II) to ~e;1 mg N/l. The detection limits were 0.7 ppb I and 0.35 ppb II. RSD (n = 5) were 1.2% for 0.7 ppm I and 1.4% for 0.28 ppm II. The method was used to determine I and II in river water and sewage effluent. The results agreed with those obtained by conventional methods (details given).
Nitrate Nitrite Chemiluminescence Gas phase detection Method comparison Permeation tube Nafion membrane Teflon membrane Phase separator

"Clean Analytical Method For The Determination Of Propoxur"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 462-468
Miguel de La Guardia*, Karim D. Khalaf, Vicente Carbonell and Angel Morales-Rubio

Abstract: An FIA method for the determination of propoxur (I) was developed based on the alkaline hydrolysis of I to produce 2-isopropoxyphenol which was subsequently treated with p-aminophenol (PAP) in the presence of KIO4 to yield an indophenol dye. A 100 µL portion of an alkaline solution of I was injected into a 0.33 M NaOH carrier stream. The carrier stream was merged with a stream formed by merging 9.3 mM PAP with 0.2 M KIO4. After passing through a reaction coil the absorbance of the flow was measured at 600 nm using a 50 µL flow cell (path length 1 cm). All flow rates were 2.2 ml/min. The waste flow from the detector was irradiated at 254 nm in the presence of TiO2 to degrade excess PAP and the reaction products and so avoid environmental pollution with these substances. The calibration graph was linear for up to 100 µg/ml of I with a detection limit of 0.12 µg/ml. The RSD (n = 3) for the determination of 5 µg/ml I was 0.8%. For the determination of low levels of I (1 µg/ml) a pre-concentration step was introduced into the sample preparation procedure involving the extraction of I into CHCl3 and back-extraction into 0.33 M NaOH. Recoveries of 0.4-10 µg/ml I from tap, well and river water were 99%.
Propoxur Spectrophotometry Preconcentration

"Determination Of Phosphorus In Turbid Waters Using Alkaline Potassium Peroxodisulphate Digestion"
Anal. Chim. Acta 1995 Volume 315, Issue 1-2 Pages 123-135
L. Woo and W. Maher*

Abstract: The evaluation of the use of alkaline peroxodisulphate digestion with autoclaving or microwave heating for the determination of total phosphorus in turbid lake and river water is described. Procedures were evaluated by the analysis of suspensions (20, 50 and 100 g P/l) of two standard reference materials, National Institute of Environmental Science, Japan No. 3 Chlorella and No. 2 Pond Sediment. Suspensions were prepared by adding these materials to distilled deionized water (pH 6) and homogenisation using shaking, sonification and stirring. Best recoveries of phosphorus were found when the final solution was 0.045 M in potassium peroxodisulphate and 0.04 M in sodium hydroxide and solutions digested in an autoclave at 120°C for 60 min. or heated in a microwave oven at 450 W for 10 min. Complete recoveries of phosphorus (99-103%) from 20, 50 and 100 g P/l Chlorella suspensions were obtained using both autoclave and microwave heating. For the Pond Sediment complete recoveries of phosphorus (99-107%) from the 20 and 50 g P/l suspensions were obtained using both heating methods. Higher recoveries from the 100 g P/l Pond Sediment suspensions were obtained using microwave heating (96 ± 1%) than autoclaving (88 ± 5%). Recoveries of phosphorus compounds (phosphates, and phosphonates) added to distilled deionized water and turbid lake water were near quantitative (91-117%) for both digestion procedures. Further analysis of Pond Sediment suspensions showed that complete recovery of phosphorus (98 ± 1%) from 60 g/l suspensions was achieved with incomplete recoveries (92.3 ± 0.7%, 91 ± 2% and 91 ± 1%) from 70 g P/l, 80 g P/l and 90 g P/l suspensions respectively. Comparison with the APHA-AWWA WPCF, nitric-sulphuric acid digestion method showed no difference in phosphorus measurements for the microwave procedure but that the autoclave procedure gave significantly lower recoveries of phosphorus (p < 0.01), however, differences were only 2-8%.
Phosphorus Sample preparation Sample preparation Reference material Method comparison

"Flow Injection Column Preconcentration Directly Coupled With Electrothermal Atomization Atomic Absorption Spectrometry For The Determination Of Aluminum. Comparison Of Column Packing Materials"
Anal. Chim. Acta 1995 Volume 316, Issue 3 Pages 313-322
Dongxing Yuan and Ian L. Shuttler*

Abstract: A method has been developed for the determination of endogenous levels of aluminum ( gt 1 µg l-1) in water samples using an automated online pre-concentration system with flow injection coupled directly to an electrothermal atomic absorption spectrometer. Two pre-concentration materials, 8-quinolinol immobilized on controlled-pore glass (8-Q-CPG) and Amberlite XAD-2, poly(styrene/divinyl benzene) copolymer (XAD-2) were investigated and compared. Both systems were found to be suitable for pre-concentration. However, the sampling flow-rate for the 8-Q-CPG system was found to be much lower than that of the XAD-2 system, relative to the same magnitude of pre-concentration. The chelating kinetics of the 8-Q-CPG system were less favourable than the adsorption kinetics of the XAD-2 system. The detection limits (3SD) varied from 15 to 40 ng l-1, depending on the pre-concentration time, with RSDs of the order of 4% for a 1 µg L-1 concentration of aluminum. The optimum concentration range for the application of the method developed was 50 ng L-1 to 3 µg l-1. Recoveries for drinking water were in the range 100-115% for the 8-Q-CPG system and 90-100% for the XAD-2 system. The method developed was applied with varying results to the analysis of potable, fresh, river and seawater samples. (23 References)
Aluminum Spectrophotometry Preconcentration 8-Hydroxyquinoline Controlled pore glass Amberlite Chelation Optimization Kinetic Immobilized reagent

"Determination Of Dissolved Silica In Waters By A Flow-based Analysis System Composed Of A Laser Diode And A Thin Long Flow-through Cell"
Anal. Chim. Acta 1996 Volume 318, Issue 2 Pages 195-202
Takashi Korenaga*,* and Fusheng Sun

Abstract: A detection system consisting of a 5 mW GaAlAs laser diode emitting at 780 nm, a cylindrical PTFE detection cell (light path up to 100 mm; 1.4 mm i.d.) and Si photodiodes as beam intensity monitors, was used in an FIA system for the determination of dissolved silica in water by the molybdenum blue method. This system permitted 300 µL of sample to be injected into a 1 g/l ammonium molybdate reagent stream at a flow rate of 1 ml/min. After passing through a reaction coil, the flow was merged with the reducing reagent stream (1 ml/min) then passed through a second reaction coil to the detector. The reaction coils (both 10 m x 1 mm i.d.) were maintained at 50°C. The reducing reagent was prepared by dissolving 30 g sodium bisulfite in 50 mL (0.01 g/l) 1-amino-2-naphthol-4-sulfonic acid/0.02 g/l sodium sulfite then diluting to 150 mL with water. A portion (80 ml) was then diluted to 1 l and diluted a further 10-fold prior to use. Calibration graphs were linear from 0.2-2, 0.1-1, 0.05-0.5 and 0.02-0.3 mg Si/l when using detection cells with light paths of 10, 20, 50 and 100 mm, respectively. Using the 100 mm light path, the detection limit was 0.0019 mg Si/l; RSD (n = 10) for the determination of 0.1 mg Si/l was 0.6%. The method was applied to the determination of ~e;5 mg Si/l in river and tap waters; recoveries of 96-104% were achieved.
Silica Spectrophotometry Laser diode Flowcell Photodiode

"Direct Determination Of Ultratraces Of Thallium In Water By Flow Injection Differential Pulse Anodic-stripping Voltammetry"
Anal. Chim. Acta 1996 Volume 318, Issue 2 Pages 159-165
Zenon Lukaszewski*, Wlodzimierz Zembrzuski and Anna Piela

Abstract: Filtered water samples were diluted with 0.2 M ETDA (3:1) and 100 mL of the solution was continuously circulated at a flow rate of 15 ml/min through a voltammetric cell during the deposition period. The voltammetric cell was equipped with a Hg film working electrode on an epoxy resin impregnated graphite substrate (3.14 mm2), a SCE as the reference electrode and a Pt wire auxiliary electrode. The deposition was carried out at -900 mV for up to 120 min. At the end of the deposition period the flow was stopped and after 30 s the voltammogram was recorded by scanning the potential to ~e;-300 mV at 11.1 mV/s with a pulse amplitude of 50 mV. The calibration graph was linear from 25-100 pM-Tl with a 90 min deposition period and the detection limit was 10 pM. The RSD (n = 6-8) was 0.14% within the calibration range. The method was tolerant of a 1000-fold excess of Pb. The method was applied to the analysis of tap, river, lake and sea waters.
Thallium Voltammetry Ultratrace Interferences

"Preconcentration And Speciation Of Chromium By The Determination Of Total Chromium And Chromium(III) In Natural Waters By Flame Atomic Absorption Spectrometry With A Chelating Ion-exchange Flow Injection System"
Anal. Chim. Acta 1996 Volume 327, Issue 1 Pages 37-45
R. M. Cesp&oacute;n-Romero, M. C. Yebra-Biurrun* and M. P. Bermejo-Barrera

Abstract: The FIA method for the determination of Cr(III) by AAS used a column (85 mm x 1.6 mm i.d.) filled with a poly(aminophosphonic acid) chelating resin (PAPhA, 20-30 mesh) for the selective retention of Cr(III) ions. Samples containing up to 140 µg/ml Cr(III) at pH 5 were pumped through the column for 90 s at 4.4 ml/min (total volume sampled = 6.6 ml). The valves were switched and the Cr(III) was eluted into a water carrier stream (4.4 ml/min) with 183 µL 0.5 M HCl for determination at 357.9 nm with an air-acetylene flame. Total Cr was determined by reducing Cr(VI) to Cr(III) with ascorbic acid and following the same procedure. The detection limit for both Cr species was 0.2 µg/l and the RSD were 1.2-5.9% for Cr(III) and 1.2-5.7% for total Cr. The method was applied to the speciation of Cr in tap, mineral and river water.
Chromium(III) Chromium, total Spectrophotometry Speciation Preconcentration Chelation

"A Novel Biosensor System For Cyanide Based On A Chemiluminescence Reaction"
Anal. Chim. Acta 1996 Volume 329, Issue 1 Pages 111-116
Kazunori Ikebukuro, Mihumi Shimomura, Noriko Onuma, Atsushi Watanabe, Yoko Nomura, Keijiro Nakanishi, Yoshiko Arikawa and Isao Karube*

Abstract: A FIA system with chemiluminescent detection was described for the determination of cyanide in river water. The determination was based on the rhodanese catalyzed reaction between cyanide and thiosulfate to yield sulfite which then reacted in the presence of sulfite oxidase to produce sulfate and H2O2. The H2O2 was detected by chemiluminescence reaction with luminol in the presence of peroxidase. The flow manifold consisted of two enzyme columns (5 cm x 2 mm i.d.) coupled in series and containing rhodanese and sulfite oxidase immobilized on reacti-gel beads (45-165 µm diameter). Sodium thiosulfate was added to the sample solution to give a final concentration of 1 mM. A portion (20 µL) of the prepared solution was injected into a 10 mM phosphate buffer carrier stream at a flow rate of 2.3 ml/min at pH 8 and transported through both enzyme columns. The flow was then merged with 7 µM-luminol/5 mg/l POD in 0.8 M carbonate buffer and the resulting luminescence was measured using a photomultiplier tube. Calibration graphs were linear from 120 nM-3.8 µM-cyanide; the detection limit was 12 nM. RSD was n = 6) for 380 nM-cyanide.
Cyanide Chemiluminescence Sensor

"Determination Of Inorganic Anions In Water Samples By Ion-exchange Chromatography With Chemiluminescence Detection Based On The Neutralization Reaction Of Nitric Acid And Potassium Hydroxide"
Anal. Chim. Acta 1996 Volume 331, Issue 3 Pages 239-244
Hiroyuki Sakai, Terufumi Fujiwara and Takahiro Kumamaru*

Abstract: The chemiluminescence reaction between HNO3 and KOH was enhanced by the presence of Fe(III) in the acid and suppressed by the presence of inorganic anions (chloride, bromide, nitrite, nitrate and sulfate) in the base. This phenomenon was utilized in a chemiluminescence detector for flow injection ion-exchange chromatography. The chromatography was carried out on an anion-exchange column (TSK gel IC-Anion-PW, 4.6 cm x 5 mm i.d.) with 7 mM KOH as the mobile phase (1 ml/min), an injection volume of 100 µl, post-column reaction with 0.09 mM Fe(III) in 7 mM HNO3 at 1 ml/min and chemiluminescence detection without wavelength discrimination. The linear dynamic range was 100 ng/ml to 100 µg/ml for each anion and the detection limits were 70 ng/ml for sulfate and nitrite, 80 ng/ml for nitrate and chloride and 100 ng/ml for bromide. The RSD (n = 5) for 10 µg/ml of each anion were 1.3-4.3%. The method was verified by LC with conductivity detection and was applied to river and ground water samples.
Anions HPIC Chemiluminescence Linear dynamic range

"Paraquat Sensors Containing Membrane Components Of High Lipophilicities"
Anal. Chim. Acta 1997 Volume 338, Issue 1-2 Pages 89-96
Bahruddin Saad*, Marinah Mohd. Ariffin and Muhammad Idiris Saleh

Abstract: Membrane-type ISE for paraquat were prepared using PVC membranes containing octamethylcyclotetrasiloxane as the sensing substance, bis-(1-butylpentyl)decane-1,1-diyl diglutarate or tetra-n-undecyl-3,3',4,4'-benzophenone tetracarboxylate as the plasticizer and sodium tetrakis-[3,5-bis(trifluoromethyl)phenyl] borate or potassium tetrakis-(4-chlorophenyl)borate as additive. The optimum compositions for the membranes were 3.6% sensor substance, 63.5% plasticizer, 30% PVC and 3% additive. The ISE were fabricated by casting the PVC membranes onto Pt electrodes and the potentiometric response to paraquat was measured against a Ag/AgCl reference electrode. All the ISE exhibited a Nernstian response to paraquat with response times of ~20 s for paraquat concentration greater than 10 µM. The detection limit was 1 µM-paraquat. The ISE were used in a FIA system with Trizma buffer at pH 5.5 as the carrier stream (2.6 ml/min) and an injection volume of 50 µL. The mean recoveries of 10 µM-paraquat from well, river and lake waters were 96.3%, 94.7% and 93.9%, respectively. The sample throughput was 85/h.
Paraquat Potentiometry Electrode Electrode Sensor Buffer

"Complex Formation Of 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfo-propy Lamino)phenol With Lead, Cadmium And Manganese For Their Sensitive Spectrophotometric Detection In Flow Injection And Ion Chromatography Systems"
Anal. Chim. Acta 1997 Volume 345, Issue 1-3 Pages 139-146
Takeshi Yamane* and Yuzuru Yamaguchi

Abstract: An ion-chromatographic method with post-column derivatization and spectrophotometric detection was developed for the simultaneous determination of Pb, Cd and Mn. Analysis was carried out on a strongly acidic cation-exchange column (7 cm x 4 mm i.d.). Elution (1 ml/min) was with 0.15 M malic acid of pH 5. The injection volume was 588 µL. The column effluent was merged with a reagent stream containing 60 µM-2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-su lfo-propylamino)phenol/0.2 M 2-(cyclohexylamino)ethanesulfonic acid/0.16 M NaOH of pH 9.4 at a flow rate of 1 ml/min. Detection was at 574 nm. Calibration graphs were linear up to 150 ng/ml Cd and Mn, and 300 ng/ml Pb; detection limits were 1.9, 1.5 and 4.8 ng/ml, respectively. RSD were 2.1%, 2.5% and 3.2% for 50 ng/ml Cd, Mn and Pb, respectively. The method was verified by analyzing rice flour CRM following microwave assisted digestion and river water samples spiked with Cd, Mn and Pb.
Lead Cadmium Magnesium HPIC Spectrophotometry Sample preparation Post-column derivatization Reference material Interferences

"Coconut-based Plant-tissue Reactor For Biosensing Of Catechol In Flow Injection Analysis"
Anal. Chim. Acta 1997 Volume 354, Issue 1-3 Pages 325-331
Antonio W. O. Lima, Valberes B. Nascimento, Jairo J. Pedrotti and L&uacute;cio Angnes*

Abstract: A novel plant tissue biosensor is proposed in this paper. Catechol is determined by the reduction of its oxidation product on glassy carbon electrode after a biocatalytic conversion to quinone in an online coconut-based reactor by flow injection analysis. The remarkably high polyphenol oxidase activity of the tissue is successfully associated to its high stability and physical feasibility to manufacture the bioreactor. The sensor retains its enzyme activity for at least one week. Catechol can be determined at micromolar range in a rate of up to 60-90 samples per hour with good precision (RSD 2%). Optimization of the experimental parameters including bioreactor and cell design is addressed. An interference study is also included showing the limitations and other possibilities of the use for this plant material. Applicability to river water analysis and waste water is illustrated. Such use of biocatalytic material apart from the electrochemical detector still holds great advantages for easy screening of new material sources for biosensing applications. 19 References
Catechol Amperometry Sensor Optimization Interferences

"Sol-gel Immobilized Room-temperature Phosphorescent Metal-chelate As Luminescent Oxygen Sensing Material"
Anal. Chim. Acta 1998 Volume 360, Issue 1-3 Pages 17-26
J. M. Costa-Fern&aacute;ndez, M. E. Diaz-Garc&iacute;a and A. Sanz-Medel*

Abstract: The chelate formed by 8-hydroxy-7-iodo-5-quinolinesulfonic acid (ferron) with aluminum exhibits strong room-temp. phosphorescence (RTP) when retained on a solid support. In a previous paper sol-gel technol. is a very useful approach for developing RTP optical sensors as a new way to immobilize lumiphors. Sol-gel active phases proved to exhibit a high phys. rigidity that enhanced relative RTP intensities and triplet lifetimes of the immobilized probe. The authors present an optical sensing phase prepared using the Al-ferron chelate which displays RTP entrapped in a sol-gel glass matrix for the determination of very low levels of oxygen both dissolved in water and organic solvents and in gaseous media. The sol-gel sensing material proved to be chemical stable for at least 6 mo under ambient storage conditions. Besides a high reproducibility in the formation of the sensing materials and no leaching or bleaching of the trapped reagent (neither in the gas phase nor in water or organic solvents) was observed Oxygen was determined by continuous-flow and flow injection methods using both intensity and triplet lifetime measurements. Both methods provided a fast response, good reproducibility and detection limits of 0.0005% (v/v) in the gas phase and <0.01 mg L-1 for dissolved oxygen. An exhaustive study of the effect of some possible interferents present in the gas phase or in solution demonstrated the high specificity of this phosphorescent probe. This highly sensitive oxygen probe was successfully applied to dissolved oxygen determinations in river and tap waters and its coupling to fiber optics for RTP in-situ monitoring or remote sensing of oxygen was evaluated.
Oxygen Phosphorescence Sol-gel Method comparison

"Determination Of Chloride By Flow Injection Spectrophotometry With Membrane Reagent Introduction"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 147-153
Stuart J. Chalk and Julian F. Tyson*

Abstract: A single line manifold incorporating three Nafion membrane reactors was developed for the sequential introduction of components of the mercuric thiocyanate/Fe(III)/acid reagent for the determination of chloride. HNO3 was introduced at the 1st reactor to give sufficient ionic strength to allow cation exchange of FeSCN2+ at the 2nd reactor, and Hg2+ at the 3rd reactor. The composition of the reagent was adjusted by control of the flow rates of donor and acceptor streams, reagent concentration. and reactor length. Calibration over the range 0.3-25 µg mL-1 was possible, though the calibration function was curved. The manifold was used to determine chloride in river water and in pond water at concentrations. of 8 and 47 µg mL-1, respectively. and gave results that were not significantly different from those obtained by an EPA method. The lower range sensitivity was 0.032 absorbance µg mL-1, which compares favorably with that of other flow injection methods, but the detection limit was 300 ng mL-1, considerably higher than that can be achieved by flow injection procedures. This was due to the presence of mixing noise caused by fluctuations in reagent concentration. related to pulsations in the flow in both donor and acceptor streams. Valve switching and refractive index effects were absent.
Chloride Spectrophotometry Nafion membrane Membrane reagent introduction

"Coupling Of Flow Injection Wetting-film Extraction Without Segmentation And Phase Separation To Flame Atomic Absorption Spectrometry For The Determination Of Trace Copper In Water Samples"
Anal. Chim. Acta 1998 Volume 370, Issue 2-3 Pages 151-161
Hengwu Chen*, Jinsong Liu and Xueqin Mao

Abstract: A flow injection wetting-film extraction system without segmentor and phase separator has been coupled to flame atomic absorption spectrometry for the determination of trace copper. Iso-Bu Me ketone (MIBK) was selected as coating solvent and 8-hydroxyquinoline (oxine) as the chelating reagent. By switching of a 8-channel valve and alternative initiation of two peristaltic pumps, MIBK, sample solution containing copper chelate of oxine, and air-segment sandwiched eluting solution (1.0 mol L-1 nitric acid) were sequentially aspirated into an extraction coil made of PTFE tubing of 360 cm length and 0.5 mm i.d. The formation of organic film in the wall of the extraction coil, extraction of the copper chelate into the organic film and back-extraction of the analyte into the eluting solution occurred consecutively when these zones aspirated into the extraction coil were propelled down the extraction coil by a carrier solution at a flow rate of 2 mL min-1. After leaving the extraction coil, the concentrated zone was transported to the nebulizer at its free uptake rate for atomization. Under the optimized conditions, an enrichment factor of 43 and a detection limit of 0.2 µg L-1 copper were achieved at a sample throughput rate of 30 h-1. Eleven determinations of a standard copper solution of 60 µg L-1 gave a relative standard deviation of 1.5%. Foreign ions possibly present in tap water and natural water did not interfere with the copper determination The developed method has been successfully used to the determination of copper content of tap water and river water.
Copper Spectrophotometry Solvent extraction 8-Hydroxyquinoline MIBK Optimization Interferences Supported liquid film

"Flow Injection Potentiometric Determination Of Free Cadmium Ions With A Cadmium Ion-selective Electrode"
Anal. Chim. Acta 1998 Volume 370, Issue 2-3 Pages 267-278
Marek Trojanowicza,*, Peter W. Alexander, b and D. Brynn Hibbertc

Abstract: The determination of free Cd ions with solid-state Cd ion-selective electrode can be performed in non-flow measurements in non-buffered solutions in a wide concentration range down to pCd 10. In Cd ion buffered solutions linear Nernstian response was obtained even down to pCd 12, which is lower, that expected based on calculation of Cd solubility from the conditional solubility product. Interferences of trace amounts of Fe(III), Cu(II) and Pb(II) commonly present in natural waters in larger concentrations than Cd(II) can be eliminated by reduction with hydroxylamine, complexation with Neocuproine and ion-exchange on anion-exchange resin in sulfate form, respectively The developed procedure might be suitable for the determination of activity of free Cd ions in natural water. A preliminary study on this subject is demonstrated for river water sample using stopped-flow flow injection system.
Cadmium(2+) Electrode Potentiometry Interferences Stopped-flow Apparatus Detector

"Room Temperature Phosphorescence Flow-through Biosensing Of Anionic Surfactants"
Anal. Chim. Acta 1998 Volume 371, Issue 1 Pages 73-80
R. Bad&iacute;a and M. E. D&iacute;az Garc&iacute;a*

Abstract: The first flow-through biosensor for anionic surfactant determination based on a sensitive room temperature phosphorescence phase (Al-Ferron) coated with bovine serum albumin was prepared, characterized and applied to the determination of sodium dodecylbenzenesulfonate in standard aqueous solution and in spiked water samples (lake, river and spring). The optosensor response to sodium dodecylbenzenesulfonate was linear from 5 x 10^-6 M to 5 x 10^-4 M which is a suitable range for the detection of anionic surfactant concentrations in polluted natural waters. The sample anal. was rapid (90% of the total response is reached in <30 s), convenient (no-sample pretreatment) and did not require organic reagents which are harmful to the environment. This work demonstrates the anal. potential of surfactant-protein interactions as a biorecognition mechanism using suitable luminescence probes.
Surfactants, anionic Phosphorescence Sensor Apparatus Detector

"Shipboard Determination Of Hydrogen Peroxide In The Western Mediterranean Sea Using Flow Injection With Chemiluminescence Detection"
Anal. Chim. Acta 1998 Volume 377, Issue 2-3 Pages 145-155
David Price, a, b, R. Fauzi C. Mantourab and Paul J. Worsfolda,*

Abstract: Field studies at a variety of sampling locations in the western Mediterranean have endorsed the use of a novel flow injection-chemiluminescence method (FI-CL) for the determination of hydrogen peroxide in seawater. Anal. time for a depth profile of 12 samples including standard additions was 45 min, repeatability (relative standard deviation; RSD; n=5) was typically <5% and reproducibilities at two different sampling stations were 2.5% RSD (mean concentration.=83.6 nM H2O2; n=3) and 1.8% RSD (mean concentration.=42.5 nM H2O2; n=4). Depth profile data, characterized by H2O2 concentrated at the surface (16.0-154 nM H2O2) and decreasing rapidly below the thermocline, were in agreement with previous studies in similar oceanog. environments. Samples collected during Lagrangian drift mode indicated that diurnal maxima can occur in the mid-late afternoon. Batches of sampled and treated seawater were incubated under ambient light conditions while onboard ship to investigate the photogeneration of H2O2. Surface waters had a higher H2O2 photogenerative efficiency than deeper waters and samples collected close to the River Rhone plume were particularly effective at generating H2O2, suggesting that the chromophoric material responsible for the photogeneration of H2O2 had a terrestrial source. Additional incubation experiments in the lab. showed that humic material was more efficient at photogenerating H2O2 than fulvic material or hydrophilic macromol. acids.
Hydrogen peroxide Chemiluminescence Remote instrument Photochemistry

"Determination Of Trace Amounts Of Phosphate In River Water By Flow Injection Analysis"
Talanta 1983 Volume 30, Issue 5 Pages 333-338
Shoji Motomizu, Toshiaki Wakimoto and Yoji T&ocirc;ei

Abstract: A flow-injection analysis system for the determination of trace amounts of phosphate in river water has been developed. The phosphate is reacted with molybdate and Malachite Green in acidic medium to form a green species, the absorbance of which is measured at 650 nm. Phosphorus (as inorganic phosphate) can be determined at the level of several ng/ml in water. Analyses can be done at a rate of up to 40 per hour.
Phosphate Spectrophotometry

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

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

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

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

"Simultaneous Determination Of Calcium And Magnesium By Using A Flow Injection System With Simultaneous Injection Of Two Sample Plugs And A Masking Agent Plug"
Talanta 1991 Volume 38, Issue 2 Pages 139-143
Takeshi Yamane* and Eiichi Goto,

Abstract: Two sample plugs were injected into a carrier stream of water, one plug was mixed with a plug of 10 mM EGTA in dilute aqueous NH3 to complex Ca. The carrier steam was merged with 0.05% of 3,3'-bis-[NN-bis(carboxymethyl)aminomethyl]-o-cresolphthalein in aqueous NH3 - NH4Cl buffer of pH 10.1 (0.5 mL min-1) then passed through a 1-m reaction coil before detection at 575 nm. One peak corresponds to Mg and the other to Mg plus Ca; Ca was determined by difference. Calibration graphs were rectilinear for at least 30 µg mL-1 of Ca or Mg. Phosphate, citrate and oxalate interfered at concentration. of ~0.5 mg mL-1. Analysis rate was 15 samples h-1. Results from the analysis of ground, river and seawater agreed well with those obtained by titration with EDTA.
Calcium Magnesium Buffer EDTA Interferences pH Titrations

"Rapid Sequential Determination Of Inorganic Mercury And Methylmercury In Natural Waters By Flow Injection - Cold Vapor-atomic-fluorescence Spectrometry"
Talanta 1992 Volume 39, Issue 11 Pages 1537-1542
Wei Jian and C. W. McLeod*,

Abstract: In the cited technique, measurement is based on time-resolved detection of inorganic and methylmercury species following separation and enrichment on a PTFE micro-column (6 cm x 1.5 mm) of sulfydryl cotton fiber (~0.015 g). The column forms an integral part of the flow injection system (described). The carrier (10 mM HCl), oxidant (Br- - BrO3-) and reductant (SnCl2) were continuously pumped at flow rates of 1.5 mL min-1 each. After injection of the sample into the carrier stream, inorganic Hg passed through the column to undergo reduction - phase separation followed by AFS detection. Hydrochloric acid (3M) was injected to eluted methylmercury from the column which was oxidized and reduced as before thus allowing a rapid sequential monitoring of both species. Optimization of the operating conditions is discussed. The calibration graph was rectilinear from 50 ng L-1 to 10 µg L-1 of methylmercury; the limit of detection was 6 ng l-1. There was no interference from co-existing metal ions. Application to river water samples is demonstrated.
Mercury Methylmercury ion Fluorescence Speciation Interferences Optimization Sulfhydryl cotton Column

"Reverse Flow Injection Analysis Of Complexing Agents And Its Application To Estimation Of Complexing Capacity"
Talanta 1993 Volume 40, Issue 1 Pages 101-106
Norio Teshima, Hideyuki Itabashi and Takuji Kawashima*,

Abstract: The redox reaction of Cu(II) with Fe(II) in the presence of neocuproine is accelerated by complexing agents such as EDTA, nitrilotriacetic acid, citrate and pyrophosphate. A CuI - neocuproine complex with max. absorbance at 454 nm is produced. A reverse flow injection system based on this reaction is described. An 80 µL portion of 0.1 mM Cu(II) - 0.5 mM neocuproine solution was injected into a carrier stream of 0.05 M acetate buffer (pH 5.6) which was merged with a 0.1 mM Fe(II) solution, followed by a complexing agent sample solution The absorbance of the complex was monitored at 454 nm. The calibration graph was rectilinear in the range 2 µM to 0.01 mM for the 4 complexing agents cited. The effects of foreign ions are discussed. For the measurement of complexing capacity (e.g., in natural water), a 20 µM concentration. of metal ion such as Al(III), Cu(II), Zn(II), Cd(II) or Pb(II) was injected into the buffer carrier which was merged with streams of complexing agent, Fe(II) and Cu(II) - neocuproine as above. The decrease in the absorbance at 454 nm was monitored. The method was applied to river and lake waters.
Complexing capacity Spectrophotometry Reverse Complexation Interferences

"Continuous-flow System For The Determination Of Trace Vanadium In Natural Waters Utilizing Inline Preconcentration/separation Coupled With Catalytic Photometric Detection"
Talanta 1998 Volume 45, Issue 3 Pages 583-589
Takeshi Yamane*, Yoshie Osada and Miho Suzuki

Abstract: A sensitive and rapid method is presented for the determination of vanadium at ng to sub ng/mL levels in natural waters, in which inline pre-concentration/separation is directly coupled with catalytic detection of vanadaium in a flow injection system. Vanadium was adsorbed on a small column packed with Sephadex G-25 gel and desorbed with a small volume of 0.010 M HCl. The catalytic action of vanadium on the oxidation of chromotropic acid by bromate in pH 3.8 buffered media was used in the sensitive determination of V. Effective pre-concentration/separation of trace vanadium can be achieved from Fe(III), Cu(II) and a large excess of NaCl in seawater sample. A linear calibration using a 5 m sample loop was obtained for 0-2.5 ng V/mL. The limit of detection was 0.02 ng/mL and the relative standard deviation was 1.2% for 1.0 ng V/mL (n = 5). This system is rapid and sensitive and can be readily applied to river water and coastal seawater samples.
Vanadium Spectrophotometry Catalysis Preconcentration Buffer Interferences Sephadex Column

"New Phase Separator For Extraction-spectrophotometric Determination Of Anionic Surfactants With Malachite Green By Flow Injection Analysis"
Talanta 1998 Volume 45, Issue 3 Pages 543-548
Tadao Sakaia,*, Hiromasa Haradaa, Xiaoqin Liua, Nobuo Uraa, Kenji Takeyoshib and Kunihiko Sugimotob

Abstract: A simple flow injection spectrophotometric method for the determination of anionic surfactants in river water was studied. A 3-channel flow system was assembled. The distilled water as a carrier and 5 x 10^-5 mol/L malachite green (MG) dissolved in 0.1 mol/L CH3COONa-CH3COOH buffer solution (pH 5) were delivered at 1.94 mL/min. The mixed solvent (toluene + methylisobutyl ketone = 1 + 1) was pumped at 0.78 mL/min. Other conditions were the extraction coil 0.5 mm i.d. x 3 m, the reaction temperature 20°C and the sample size 200 µL. The calibration graph was linear at 0.1-0.4 ppm and 626 nm. The detection limit (S/N = 3) was 18 ppb and a sample frequency of 20/h was attained. The relative standard deviation (n = 7) for 0.4 ppm standard Na dodecylsulfate solutions was 1.1%. A phase separator with a convenient connector was designed. This method was applied to the determination of anionic surfactants in river water.
Surfactants, anionic Spectrophotometry Buffer Solvent extraction MIBK Phase separator Apparatus

"Inorganic And Methylmercury Speciation In Environmental Samples"
Talanta 1998 Volume 47, Issue 3 Pages 509-524
J. E. S&aacute;nchez Ur&iacute;a* and A. Sanz-Medel

Abstract: The different strategies for mercury species analysis in environmentally-related samples are reviewed. After consideration of the main different steps involved in the speciation of mercury, such steps are discussed with more extension for mercuric ion and methylmercury. The different approaches for preservation of these mercury species during the storage of samples are considered. Different ways for the extraction of mercury species from the several possible environmental compartments and the possibilities for pre-concentration of such species after previous derivatization reactions are discussed. Mercuric ions and methylmercury chromatographic and non-chromatographic separations along with different techniques used for sensitive and selective detection of mercury are also critically reviewed. Ranges of published detection limits achievable for such species determination, by using hyphenated techniques between a chromatographic separation and a specific atomic detector are also given.
Mercury(II) Methylmercury ion Speciation C18 Preconcentration Review Volatile generation Extraction Reference material

"Flow Injection Analysis With Tubular Membrane Ion-selective Electrodes In The Presence Of Anionic Surfactants"
Analyst 1983 Volume 108, Issue 1292 Pages 1357-1364
Anthony J. Frend, Gwilym J. Moody, J. D. R. Thomas and Brian J. Birch

Abstract: Ion-selective electrodes for Ca(II) based on a PVC-matrix membrane containing Ca bis{bis-[4-(1,1,3,3-tetramethylbutyl)phenyl] phosphate} as sensor and trioctyl phosphate as solvent mediator are shown to be able to discriminate against Na dodecyl sulfate and Na tetradecylbenzenesulfonate in flow injection analysis. Levels of Ca(II) have been determined with use of tubular membrane electrodes in flow injection analysis for three types of tap-water, for river water and for lake water, and are in good agreement with values obtained by AAS and by EDTA titration; such electrodes allow determination of 0.1 mM Ca(II) in the presence of a moderate amount of detergent. This sensitivity compares poorly with the level of free Ca(II) (<10 µM) determinable by using a conventional-type electrode with the same membrane system under static conditions.
Calcium Electrode Electrode Electrode Tubular membrane

"Spectrophotometric Determination Of Phosphorus As Orthophosphate Based On Solvent Extraction Of The Ion Associate Of Molybdophosphate With Malachite Green Using Flow Injection"
Analyst 1987 Volume 112, Issue 3 Pages 295-300
Shoji Motomizu and Mitsuko Oshima

Abstract: Samples (30 µL) of river water were injected into a carrier stream of 5 mM H2SO4 and mixed with a reagent stream which was 80 µM in malachite green (C. I. Basic Green 4), 80 mM in Mo (as ammonium molybdate) and 0.8 M in H2SO4. The mixture was extracted with benzene - isobutyl methyl ketone (1:2) during passage through an extraction coil and a modified phase segmenter. The absorbance of the organic extract was measured at 630 nm. Rectilinear calibration graphs were obtained for up to 30 ng mL-1 or up to 1 µg mL-1 of P for 300 µL or 10 µL aliquots, respectively. Detection limits of 0.1 ng mL-1 of P were achieved.
Phosphate Spectrophotometry Sample preparation Organic phase detection Solvent extraction

"Determination Of PH, Conductivity, Residual Chlorine And Ammonium And Nitrite Ions In Water With An Unsegmented Flow Configuration"
Analyst 1988 Volume 113, Issue 5 Pages 739-742
F. Ca&ntilde;ete, A. R&iacute;os, M. D. Luque de Castro and Miguel Valc&aacute;rcel

Abstract: A flow injection arrangement is described that includes potentiometric, conductometric and photometric detectors in a reversed-flow injection configuration. Conductivity and pH were monitored continuously. The Cl was determined with o-toluidine in 2 M HCl at 438 nm in the range 0.03 to 1.3 µg mL-1, with a coefficient of variation of 1.47% for 0.5 µg mL-1. In the presence of NO2-, Cl was measured with methyl orange in 15 mM HCl - 0.1 M KCl at 504 nm from 1.5 to 3.0 µg mL-1, with coefficient of variation of 1.43 and 1.95% for 0.9 and 2.0 µg mL-1, respectively. Ammonia was determined with Nessler reagent in 2 M NaOH at 380 nm in the range 0.05 to 0.9 µg mL-1, with a coefficient of variation of 2.44% for 0.45 µg mL-1. The NO2- was determined with sulfanilamide - N-1-naphthylethylenediamine in concentrated HCl at 540 nm from 0.05 to 1.3 µg mL-1, with a coefficient of variation of 2.2% for 0.45 µg mL-1. The method was successfully applied in the analysis of drinking and river water.
Chlorine, residual Conductivity Ammonium Nitrite pH Conductometry Potentiometry Spectrophotometry Interferences Merging zones Reverse

"Spectrophotometric Determination Of Anionic Surfactants In Water After Solvent Extraction Coupled With Flow Injection"
Analyst 1988 Volume 113, Issue 5 Pages 747-753
Shoji Motomizu, Mitsuko Oshima and Toshinori Kuroda

Abstract: Eight cationic dyes and various extraction media were studied for the cited determination, and optimum conditions were established. The samples were extracted with 1,2-dichlorobenzene after reaction with a reagent stream comprising 50 µM-methylene blue (C. I. Basic Blue 9), 0.1 M Na2SO4 and acetate buffer (pH 5) at 0.8 mL min-1. The carrier stream was water. The absorbance was measured at 658 nm. For Na dodecyl sulfate, response was rectilinear up to 30 µM for 300 µL injections and up to 70 µM for 100 µL, and the limit of detection was 18 nM for 300 µL. The coefficient of variation of peak height measurements was 0.9% (n = 10) for 2.1 µM-Na dodecyl sulfate. Results for some river-water samples agreed with those obtained by a batch method.
Surfactants, anionic Spectrophotometry Sample preparation Method comparison Optimization Solvent extraction

"Spectrophotometric Determination Of Potassium In River Water Based On Solvent Extraction Of The Complex Formed With Crown Ether And An Anionic Azo Dye Using Flow Injection"
Analyst 1988 Volume 113, Issue 5 Pages 743-746
Shoji Motomizu, Minoru Onoda, Mitsuko Oshima and Tadashi Iwachido

Abstract: Potassium was extracted into benzene - chlorobenzene (1:1) as its complex with benzo-18-crown-6(I) with ethyl orange(II) as the counter ion, in an extraction coil (100 cm x 0.5 mm). The carrier stream was water, and the reagent stream comprised 0.5 mM II, 2 mM I, 1 mM Li2EDTA and 3 mM LiOH, at 0.8 mL min-1. The absorbance was measured at 450 nm, with rectilinear response up to 0.1 mM K, and a limit of detection of 3 µM. The coefficient of variation (n = 10) for 50 µM- and 0.1 mM K were 0.4 and 0.3%, respectively. Results for various river-water samples were in good agreement with those obtained by AAS.
Potassium Spectrophotometry Sample preparation Complexation Crown ether Method comparison Solvent extraction

"Spectrophotometric Determination Of Low Levels Of Anionic Surfactants In Water By Solvent Extraction In A Flow Injection System"
Analyst 1988 Volume 113, Issue 11 Pages 1677-1681
Manuel del Valle, Julian Alonso, Jordi Bartrol&iacute; and Isabel Mart&iacute;

Abstract: A method was devised for the automated monitoring of river and treatment-plant waters with use of ion-pair extraction with methylene blue (C. I. Basic Blue 9) in CHCl3 in a PTFE flow injection system. The water was merged sequentially with streams of 0.2% methylene blue solution in phosphate - sulfate buffer of pH 2 and CHCl3 - methanol (9:1) for extraction of the complex. A 70 µL portion of the organic phase was then injected into CHCl3 for absorbance measurement at 660 nm. The method was suitable for anionic surfactants, e.g., sodium dodecyl sulfate and sodium dodecylbenzenesulfonate, sodium dioctyl sulfosuccinate, triethanolamine dodecyl sulfate and alk-1-ene sulfates.
Surfactants, anionic Sodium dodecyl sulfate Sodium dodecylbenzenesulfonate Sodium dioctyl sulfosuccinate Triethanolamine dodecyl sulfate Spectrophotometry Sample preparation Automation Interferences Optimization Ion pair extraction Organic phase detection Solvent extraction

"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

"Differential Determination Of Chromium(VI) And Total Chromium In Natural Waters Using Flow Injection Online Separation And Preconcentration Electrothermal Atomic Absorption Spectrometry"
Analyst 1992 Volume 117, Issue 3 Pages 629-635
Michael Sperling, Xuefeng Yin and Bernhard Welz

Abstract: Samples were introduced into the FIA manifold and mixed with 4% HNO3 (to adjust the pH to 1.3 to 1.8) and 0.05% Na diethyldithiocarbamate solution (as complexing agent). The solution was applied to a column of RP-C18 and Cr(VI) was eluted with ethanol before determination with graphite-furnace AAS. Total Cr was determined after oxidation of Cr(III) to Cr(VI) by K peroxydisulfate and Cr(III) was calculated by difference. Detection limits for Cr(VI) and total Cr were 16 and 18 ng 1-1, respectively. The results for six reference samples agreed well with the certified values, with a coefficient of variation of 10%. A rapid, sensitive, and selective method for the differential determination of Cr(III) and Cr(VI) in natural waters is described. Cr(VI) can be determined directly by flow injection online sorbent extraction pre-concentration coupled with electrothermal atomic absorption spectrometry using Na diethyldithiocarbamate as the complexing agent and C18 bonded SiO2 reversed-phase sorbent as the column material. Total Cr can be determined after oxidation of Cr(III) to C(VI) by potassium peroxydisulfate. Cr(III) can be calculated by difference. The optimum conditions for sorbent extraction of Cr(VI) and oxidation of Cr(III) to Cr(VI) are evaluated. A 12-fold enhancement in sensitivity compared with direct introduction of 40 µL samples was achieved after pre-concentration for 60 s, giving detection limits of 16 ng/L for Cr(VI) and 18 ng/L for total Cr. Results obtained for seawater and river water reference materials were all within the certified range for total Cr with a precision of >10% relative standard deviation at 100-200 ng/L. The selectivity of the determination of Cr(VI) was evaluated by analyzing spiked reference materials in the presence of Cr(III) resulting in quant. recovery of Cr(VI).
Chromium(VI) Chromium, total Spectrophotometry Sample preparation C18 Reference material Solid phase extraction Optimization Preconcentration

"Micelle-mediated Methodology For The Preconcentration Of Uranium Prior To Its Determination By Flow Injection"
Analyst 1993 Volume 118, Issue 2 Pages 209-212
Ma. Esther Fern&aacute;ndez Laespada, Jos&eacute; Luis P&eacute;rez Pav&oacute;n and Bernardo Moreno Cordero

Abstract: The method was based on the pre-concentration. of the U(VI) - 1-(2-pyridylazo)-2-naphthol (I) complex by incorporation into Triton X-114 (II) micelles which underwent phase separation from the solution when heated to above the cloud point temperature (23°C to 25°). A 5 mL sample, e.g., containing 0.1 mM I and 0.25% of II (pH adjusted to 9.2 with 4 mM HBO2 - BO2- buffer) was kept for 5 min at 40°C giving two phases which were separated by centrifugation. On cooling in an ice bath the surfactant-rich phase became viscous and the aqueous phase could be poured away. After adding 3.6 M HCl to destroy the U(VI) - I complex an aliquot of the micellar phase (100 µL) was injected into a stream of 3.6 M HCl at 1.7 mL min-1 which was then passed through a Pb powder reduction column and mixed with a stream of 0.2 mM Arsenazo III in 3.6 M HCl containing 1% of Triton X-100 (1.7 mL min-1) before detection of the U(VI) by measuring the absorbance at 665 nm. For 1- to 100-fold pre-concentration, calibration graphs were rectilinear and detection limits were 1.1 to 38 ppb of U(VI). In the determination of 0.15 µM-U(VI) after ten-fold pre-concentration. the coefficient of variation was 5.1% (n = 8). Phosphate, CO32-, Th and Zr interfered, Zr being masked with oxalic acid, while there was insignificant interference from Ni(II), Fe(III), Cu(II), Al, Ca, Zn, Co(II), SO42- and humic acids. When the method was applied to tap and river water samples containing 25 to 50 ppm of U(VI) the concentration. found were 26 to 56 ppm.
Uranium Spectrophotometry Preconcentration Triton X Surfactant Micelle Interferences Reduction column

"Speciation Of Mercury In Natural Waters By Capillary Gas Chromatography With A Microwave-induced Plasma Emission Detector Following Preconcentration Using A Dithiocarbamate Resin Micro-column Installed In A Closed Flow Injection System"
Analyst 1993 Volume 118, Issue 8 Pages 1007-1013
H&aring;kan Emteborg, Douglas C. Baxter and Wolfgang Frech

Abstract: The water sample (neutralized, if necessary, by CaCO3 powder) was pumped at 8 ml/min through a column (9.7 mm x 2.8 mm), in a semi-automated closed flow injection system, of Spheron E 300 resin spheres incorporating dithiocarbamate groups, which was pre-treated with 5% thiourea solution (adjusted to pH 1 with HNO3) to remove Hg species. The Hg species enriched on the column were eluted by the acidic thiourea solution, extracted at pH 9 (attained with NaOH and borate buffer) into toluene after complexation with diethyl dithiocarbamate and derivatized with butylmagnesium chloride in THF. After decomposing excess of Grignard reagent with HCl, the toluene was evaporated at 0°C and the products were analyzed by GC, with use of a deactivated fused-silica retention gap pre-column (10 m x 0.53 mm) and a fused-silica column (15 m x 0.53 mm) coated with 1.5 µm of DB-1 and operated under temp.-programmed conditions (details given). The carrier gas was He and the analytical column was coupled to an atmospheric pressure He plasma sustained in a Beenakker TM010 cavity and operated at 125 W forward power for AES detection at 253.7 nm. The detection limits were 0.05 ng/l for methyl- and ethylmercury and 0.15 ng/l for inorganic Hg. The method was applicable to fresh and brackish water but not to samples containing high levels of humic substances.
Mercury Spectrophotometry Speciation Preconcentration Resin

"Flow Injection Spectrophotometric Method For The Speciation Of Aluminum In River And Tap Waters"
Analyst 1993 Volume 118, Issue 9 Pages 1199-1203
Ma Jos&eacute; Quintela, Mercedes Gallego and Miguel Valc&aacute;rcel

Abstract: The cited method is based on a pyrocatechol violet chelation - ion-exchange method and is an automated version of the manual Driscoll method. A 280 µL volume of sample containing 10^-1000 µg/l of Al was injected into a carrier solution including an Fe-masking reagent after merging with the pyrocatechol violet reagent and then with hexamethylenetetramine buffer solution of pH 8.2 (for total and non-labile monomeric Al) or pH 8.8 (for total reactive Al). Complex formation took place in a 280 cm coil (pH 6.1-6.2) and the absorption was measured at 580 nm. The detection limit was 5 muwg/l of Al and the calibration graphs were rectilinear from 10^-80 µg/l and from 80-1000 µg/l; the RSD were 1.8 and 0.65%, respectively. The sample throughput was 40-50/h.
Aluminum Spectrophotometry Speciation Complexation

"Continuous-flow Determination Of Low Concentrations Of Urea In Natural Waters Using An Immobilized Urease Enzyme Reactor And An Ammonia Gas-sensing Membrane Electrode Detector System"
Analyst 1993 Volume 118, Issue 10 Pages 1317-1320
Hirokazu Hara, Tomoko Kitagawa and Yohzoh Okabe

Abstract: Water was mixed with an alkaline reagent solution, which comprised 0.2 M NaOH, 0.12 M Na2HPO4, 0.08 M KH2PO4, 0.02 M Na2H2EDTA, 0.01 M sodium azide and 0.5 mM dithiothreitol, then passed through a gas-permeable PTFE tube; this effectively removed co-existing ammonium ions up to a concentration of 0.2 mM. The alkaline eluate was passed through a second gas-permeable tube immersed in HCl to bring the solution back to neutral pH without contamination from the acid solution Urea was enzymatically decomposed into ammonium ions by passage through the immobilized urease enzyme reactor, then detected as NH3, after the addition of NaOH, by an NH3 gas-sensing membrane electrode. The detection limit was 0.1 µM-urea and the limit for a linear response was 1 µM. In the analysis of river water, recoveries were ~100% and the RSD (n = 5) was 7.6%.
Urea Electrode Immobilized reagent

"Continuous-flow Method For The Determination Of Phenols At Low Levels In Water And Soil Leachates Using Solid-phase Extraction For Simultaneous Preconcentration And Separation"
Analyst 1996 Volume 121, Issue 1 Pages 1-6
Zheng-liang Zhi, Angel R&iacute;os and Miguel Valc&aacute;rcel

Abstract: Soil was extracted with water and filtered. Water (tap, river) was filtered. The filtrates were adjusted to pH 2 with 12 M HCl and the ionic strength was brought to 0.34 M with NaCl. The sample was pumped continuously (4.8 ml/min) for 5 min through a column (4 cm x 2.5 mm i.d.) of Amberlite XAD-4, previously conditioned with 0.01 M HCl. The column was then washed with water at pH 2 for 30 s. Elution of the analytes was effected by continuously passing a stream (1 ml/min) of 0.1 M NaOH through the column. The eluate was merged with a stream (0.4 ml/min) of 1% 4-aminoantipyrine in borate buffer of pH 9-10, then with a stream (1 ml/min) of 4% K2S2O8 of pH 11 and finally with a stream (1 ml/min) of CHCl3 propelled from a displacement bottle. The mixture was passed through a 2 m extraction coil and the aqueous and organic phases were separated by means of a membrane phase separator. The absorbance of the organic phase was measured at 460 nm. The calibration graph was linear for 0.5-60 ng/ml phenol, the detection limit was 0.2 ng/ml and the RSD (n value not given) was 2.7%. The throughput was 8 samples/h. Recoveries of phenol were 91.6-108.3%.
Phenols Spectrophotometry Sample preparation Preconcentration Amberlite Phase separator Solid phase extraction

"Determination Of Trace Amounts Of Cadmium In A Hydrometallurgical Zinc Refining Process Stream By A Flow Injection Method With Online Preconcentration And Spectrophotometric Detection"
Analyst 1996 Volume 121, Issue 1 Pages 7-11
Yutaka Hayashibe and Yasumasa Sayama

Abstract: Zinc electrolyte (350 µL) was injected into a carrier stream (1 ml/min) of 0.1 M KI and passed through a column (10 cm x 1 mm i.d.) of Bio-Rad AG1-X8 anion-exchange resin (100-200 mesh, chloride form). At 220 s after sample injection, the cadmium-iodo complex was eluted from the column with a stream (1 ml/min) of 1 M HNO3. The eluate was merged with a stream (1.5 ml/min) containing a mixture of 0.002% Cadion/0.1 M KOH/0.1% Triton X-100 (reagent solution) and 17 mM trisodium citrate/8.8 mM potassium sodium tartrate/2 M KOH (masking agent solution) and the absorbance of the Cd-Cadion complex was measured at 480 nm. A multiple sample injection method, in which 350 µL portions of the sample were repeatedly injected into the carrier stream at 30 s intervals, was also applied. For the single injection method, the calibration graph was linear for 0.05-2 µg/ml Cd, the detection limit was 0.028 µg/ml, the RSD (n = 5) was 5% and the throughput was six samples/h. For the multiple injection method (50 injections), the calibration graph was linear for 2-40 ng/ml Cd, the detection limit was 0.83 ng/ml, the RSD (n = 5) was 10% and the throughput was two samples/h. The method was also applied to river water.
Cadmium Spectrophotometry Preconcentration Triton X Surfactant

"Flow Dissolution Of 1,5-diphenylcarbazide For The Determination Of Chromium(VI)"
Analyst 1996 Volume 121, Issue 5 Pages 613-616
Francisco J. Andrade, Mabel B. Tudino and Osvaldo E. Troccoli

Abstract: A flow injection spectrophotometric method for Cr(VI) determination is described. Sample (0.3 ml) was injected into a carrier stream (4 ml/min) of 0.8 M HNO3. The mixture was passed through a PTFE column (5 cm x 2 mm i.d.) packed with 25% 1,5-diphenylcarbazide (DPC) and silica. The absorbance of the Cr(VI)-DPC complex formed was then measured at 540 nm. Beer's law was obeyed up to 0.8 mg/l of Cr(VI); the detection limit was 0.005 mg/l and the RSD (n = 10) was 1%. The throughput was 120 samples/h. The method was applied to river water. The results obtained agreed with those obtained by AAS. Recoveries of Cr(VI) from spiked river water were 80%.
Chromium(VI) Spectrophotometry Method comparison Solid phase reagent Silica

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

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

"Determination Of Ammonia In Waste Waters By A Differential PH Method Using Flow Injection Potentiometry And A Nonactin-based Sensor"
Analyst 1997 Volume 122, Issue 1 Pages 89-93
Hongda Shen, Terence J. Cardwell and Robert W. Cattrall

Abstract: A water sample (20 µL) was injected into a water stream (0.9 ml/min) which merged with a stream (0.9 ml/min) of 0.6% acetic acid buffer of pH 6 containing 0.84% LiCl and 0.42% LiOH, then passed through a PTFE reaction coil (20 cm x 0.5 mm i.d.) prior to detection. The potential was recorded at a nonactin-based ammonium ion-selective sensor (fabrication described) vs. Ag/AgCl and a reference stream (0.9 ml/min) of 0.15 M LiCl (diagram of FIA system given). A second analysis was carried out, using LiCl/LiOH/0.75% boric acid buffer of pH 9.4 containing 0.84% LiCl, 0.42% LiOH and 5 µM-KCl in place of the pH 6 buffer. The difference between the potentials recorded with the different buffers was used to determine NH3 by a chemometric technique (details given). The use of this approach enabled the interference from moderate concentrations of K and Na to be corrected. Calibration graphs were linear (graphs shown) and the determination limit was ~1 µM. Recoveries and RSD are presented. The throughput was 30 samples/h. The method was applied to waste water and river water. The results were compared to those obtained by a gas diffusion technique.
Ammonia Potentiometry Electrode Sensor Chemometrics pH Buffer Method comparison Interferences Gas diffusion

"Determination Of Trace Amounts Of Zinc In Water Samples By Flow Injection Isotope-dilution Inductively Coupled Plasma Mass Spectrometry"
Analyst 1997 Volume 122, Issue 3 Pages 233-237
Tarn-Jiun Hwang and Shiuh-Jen Jiang

Abstract: A water sample (25 ml) was adjusted to pH 4 with 5 mL 1 M ammonium acetate buffer. After a suitable amount of Zn-67 had been added, the solution was diluted to 50 mL with water. A portion (10 ml) of the resulting solution was loaded at a flow rate of 10 ml/min on to a column (5 cm x 10 mm i.d.) of SO3-quinolin-8-ol carboxy-methylcellulose. The column was washed with 0.1 M ammonium acetate buffer of pH 4; the retained Zn was eluted (3 ml/min) with 0.5 M HNO3. The eluate was analyzed by ICP-MS (details given). The Zn-66/Zn-67 isotope ratio was calculated from the peak areas of the flow injection peaks. The calibration graph was linear up to 50 ng/ml Zn-66; the detection limit was 14 pg/ml. RSD was 1.4% (n=7). The method was applied to several water CRM; the results agreed with the certified values.
Zinc-66 Zinc-67 Mass spectrometry Mass spectrometry Column Detection limit Reference material Buffer

"Flow Injection Detector Incorporating A Screen-printed Disposable Amperometric Biosensor For Monitoring Organophosphate Pesticides"
Analyst 1997 Volume 122, Issue 11 Pages 1425-1429
J. J. Rippeth, T. D. Gibson, J. P. Hart, I. C. Hartley and G. Nelson

Abstract: The construction of a wall-jet flow cell, which houses a screen-printed amperometric pesticide biosensor, together with a complete flow injection system, is described. This system was initially employed in studies to stabilise the enzyme acetylcholinesterase (AChE), which was immobilized on a cobalt phthalocyanine screen-printed carbon electrode to form a biosensor. A combination of dextran sulfate and lactitol, and carbodiimide for enzyme immobilization, resulted in biosensor lifetimes of at least 76 d (at 37°C). Flow injection and biosensor conditions were optimized, then the system was evaluated by monitoring the model organophosphate pesticides (OP) dichlorvos and paraoxon. The detection limits were 7 x 10^-11 mol L-1 (for 1 U of AChE) and 4 x 10^-11 mol L-1 (for 0.05 U of AChE), respectively, which are better than for other electrochemical methods. Initial evaluations on two river water samples have been carried out to test the validity of the system for OP determination in field samples.
Pesticides, organophosphorus Amperometry Sensor Electrode Optimization Method comparison

"Flow Injection Determination Of Anionic Surfactants With Cationic Dyes In Water Bodies Of Central India"
Analyst 1998 Volume 123, Issue 8 Pages 1691-1695
Rajmani Patel and Khageshwar Singh Patel

Abstract: A new, simple and specific flow injection analysis (FIA) procedure for the determination of anionic surfactants, viz., sodium lauryl sulfate (SLS), sodium dodecyl sulfonate, sodium hexadecyl sulfonate and sodium dodecyl benzenesulfonate, with cationic dyes, viz., Brilliant Green, Malachite Green, Methylene Blue, Ethyl violet and Crystal Violet, in water bodies, viz., ponds, tube wells, rivers and municipal wastes, of central India (east Madhya Pradesh) is described. It is based on the precipitation of the cationic dyes with the anionic surfactant due to formation of an ion-associated species within the pH range 5.5-8.0. The apparent molar absorptivity of the ion-associated species formed with various anionic surfactants and cationic dyes is in the range (0.60-1.50) x 104 L mol-1 cm-1 at λmax 590-665 nm. Among them, the pair BG+-LS- was selected for detailed investigation. The detection limit (amt. causing absorbance >3s) of the method with BG is 100 ppb SLS and the sample throughput is 50 h-1. Optimization of FIA and the anal. variables in the precipitation and determination of SLS with BG is described. The method is free from interferences from almost all ions which are commonly present with the surfactant. The proposed method was applied to the mapping of SLS pollution levels in the various water bodies. All surface waters and municipal waste waters and some ground waters lying near the sources were found to be contaminated with SLS beyond permissible limits.
Surfactants, anionic Sodium lauryl sulfate Sodium dodecyl sulfonate Sodium hexadecyl sulfonate Sodium dodecylbenzenesulfonate Spectrophotometry Ion pair formation pH Optimization Interferences

"Fluorimetric Flow Injection Method For Anionic Surfactants Based On Protein-surfactant Interactions"
Analyst 1998 Volume 123, Issue 11 Pages 2257-2261
D. L. Recalde Ruiz, A. L. Carvhalo Torres, E. Andr&eacute;s Garc&iacute;a and M. E. D&iacute;az Garc&iacute;a

Abstract: Surfactant-protein interactions have been widely used to study the composition of biopolymers, but their application in the quant. anal. of surfactants has not been exploited. The anal. figures of merit of a sensitive spectrofluorimetric flow injection system for the determination of an anionic surfactant, Na dodecyl sulfate (SDS), are reported. The proposed method is based on the interactions of SDS with bovine serum albumin, a surface active protein, in the presence of a fluorescent probe, 8-anilino-1-naphthalenesulfonic acid. The linear dynamic range extends from the limit of quantification ≤1 x 10^-4 M SDS under selected conditions. The relative standard deviation is 4% with a detection limit of 2 x 10^-6 M SDS. The method was applied to the determination of SDS in river and tap water samples. A mechanism for the sensing chemical involved is proposed.
Surfactants, anionic Sodium dodecyl sulfate Fluorescence Optimization

"Preconcentration And Inductively Coupled Plasma Atomic Emission Spectrometric Determination Of Metal Ions With Online Chelating Ion Exchange"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 1 Pages 19-22
Valerio Porta, Corrado Sarzanini, Ornella Abollino, Edoardo Mentasti and Enzo Carlini

Abstract: An online pre-concentration method utilizing a microcolumn of XAD-2 resin functionalized with 1-(2-thiazolylazo)-2-naphthol was developed. Preconcentration factors of 125 were obtained for injection times of 5 min. The detection limit ranged between 2 for manganese and 40 ng/L for nickel. The resin was used to pre-concentrate Cd, Cu, Fe, Mn, Ni, and Zn from river water and Antarctic seawater (Ross Bay) prior to their determination by inductively coupled plasma atomic emission spectrometry. The precision of the technique is ~10% relative standard deviation at concentrations below the µg/L level and 5% for higher concentrations.
Cadmium Copper Iron Manganese Nickel Zinc Ion exchange Spectrophotometry Preconcentration Amberlite Resin Chelation

"Development Of An Atomic-fluorescence Spectrometer For The Hydride-forming Elements"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 1 Pages 71-77
Warren T. Corns, Peter B. Stockwell, Les Ebdon and Steve J. Hill

Abstract: The covalent hydrides of As and Se were generated in a PSA 10.003 automated continuous-flow system (PS Analytical, Sevenoaks, UK) by merging the sample solution in 3 M HCl with 1.5% NaBH4 solution in 0.1 M NaOH; the mixture was passed through a gas - liquid separator, where the hydrides were entrained by Ar and passed through a hygroscopic membrane tube around which a dryer gas was circulated. The detection system incorporated an atomizer cell, a boosted-discharge hollow cathode lamp for excitation, and a solar blind photomultiplier. Of the four atom cell designs investigated, a simple design comprising a 10-cm borosilicate glass tube (5 mm o.d.; 3 mm i.d.) supporting a small Ar - H diffusion flame gave the best results and required no additional supply of H. Under optimized conditions (reported), which involved the use of a narrow-bandwidth interference filter (200±10 nm), the detection limits for As and Se were 0.1 and 0.05 µg L-1, respectively. The technique was used to analyze certified reference fresh and saline water samples with good accuracy and precision; preliminary reduction of As(V) was effected with KI, and of Se(VI) with HCl at 70°C.
Arsenic Selenium Fluorescence Volatile generation Reference material Phase separator Optimization Interferences Volatile generation

"Determination Of Antimony By Continuous Hydride Generation Coupled With Nondispersive Atomic Fluorescence Detection"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 11 Pages 969-974
Alessandro D'ulivo, Leonardo Lampugnani, Giovanna Pellegrini and Roberto Zamboni

Abstract: A sensitive method for the determination of Sb at ultratrace levels was developed by coupling continuous hydride generation with non-dispersive atomic fluorescence detection. A miniature argon-hydrogen diffusion flame was employed as the atomizer and a commercially available electrodeless discharge lamp as the light source, One of the main problems was the scattering signal generated by small droplets of solution which markedly deteriorated the signal-to-noise ratio. A simple way to remove the scattering signal was to operate under mild reaction conditions in order to minimize droplet formation. Under the optimized conditions, a limit of detection of 22 pg cm(-3) of Sb (3s of the blank) was achieved, with a precision of 1.2% at the 5 ng cm(-3) level and the calibration graphs were linear over more than 4 decades of concentration, L-Cysteine was employed both in the pre-reduction step and in the control of the interference effects arising from concomitant elements and acid mixtures, The analytical procedure was applied to the determination of Sb in certified reference materials of sediments, metallic copper and riverine water. (29 References)
Antimony Fluorescence Optimization Reference material Volatile generation Interferences Ultratrace Volatile generation

"Flow Injection Determination Of Mercury With Preconcentration By Amalgamation On A Gold-platinum Gauze By Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 2 Pages 127-132
Ebenezer Debrah, Eric R. Denoyer and Julian F. Tyson

Abstract: River and seawater and tin(II) chloride as a reductant passed into a gas-liquid separator in a flow injection system. Two separators were evaluated, one partially filled with glass beads (cf. Hanna et al., Ibid., 1993, 8, 585) and the other containing an exchangeable PTFE membrane filter. Separation took place under Ar and the atomic mercury vapor generated by the reductant passed through a fiber filter to remove water and was trapped on a 1.2 cm length of rolled Au/Pt gauze in a quartz tube (3 mm i.d.). The gauze was heated to 600°C by two 10 W tungsten filament lamps to release the Hg and then the system was cooled by compressed air. The released Hg was measured by ICP-MS with an Ar plasma; operating conditions tabulated. Detection limits for Hg were 200 pg/l in a 25 mL sample. The RSD (n = 21) was 0.9% for 1 µg/l of Hg using 1.1% tin(II) chloride and recoveries from sea and river water were 83-103%.
Mercury Mass spectrometry Preconcentration Amalgamation Glass beads Teflon membrane

"Evaluation Of Electrochemical Hydride Generation For The Determination Of Total Antimony In Natural-waters By Electrothermal Atomic Absorption Spectrometry With In-situ Concentration"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 3 Pages 225-230
W.-W. Ding and R. E. Sturgeon

Abstract: A continuous-flow (timed injection) electrochemical hydride generation system was developed for the determination of total Sb in river water and seawater. Lead was used as cathode material for the production of stibine. Both Sb-III and Sb-V were equally converted into their hydrides by electrochemical means with 92±4% efficiency. The hydride was trapped in a Pd-coated graphite furnace prior to atomization. An absolute detection limit of 45 pg (3s(blank)) and a concentration detection limit of 0.02 µg L-1 were obtained using 2 mi sample volumes. The precision of replicate measurements at the 0.2 pg L-1 level (0.5 ng absolute mass level) was better than 6% relative standard deviation. The accuracy of the approach was verified through the analysis of National Research Council of Canada certified reference materials SLRS-2 and SLRS-3 River Water and NASS-4 Open Ocean Seawater.
Antimony, total Spectrophotometry Electrochemical product generation Reference material Interferences Timed injection

"Electrochemical And Chemical Processes For Hydride Generation In Flow Injection ICP-MS: Determination Of Arsenic In Natural Waters"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 12 Pages 1343-1346
Luis Fernando R. Machado, Antonio Oct&aacute;vio Jacintho, Amauri A. Meneg&aacute;rio, Elias A. G. Zagatto and Maria Fernanda Gin&eacute;

Abstract: A flow injection system involving hydride generation is proposed for the determination of arsenic in natural waters by inductively coupled plasma mass spectrometry. The manifold was designed to permit a direct comparison between chemical (NaBH4) and electrochemical (EcHG) processes for hydride generation, using sodium tetrahydroborate or a Nafion membrane, respectively. Reactions were carried out in different manifold sites, separation/transportation of the evolved gaseous species and quantification occurred in the same devices under similar conditions. Interferences by Co(ii), Ni (ii), Cu(ii), Zn(ii) and Pb(ii) were evaluated for both systems. When NaBH4 was used, addition of these species decreased the As signal, whereas for electrochemical arsine formation, the interference effects were dependent on the Pt cathode conditions. Interferences due to the above metals were modified when the cathode underwent Pb deposition. About 60 samples were run per h and the measurement precision for 10 µg/L As was characterized by an RSD <3%. A higher sensitivity was verified for NaBH4 (LOD = 0.05 µg/L As) than EcHG (0.2 µg/L As). Accuracy was assessed by using standard reference materials and spiked river water samples.
Arsenic Mass spectrometry Electrode Spectrophotometry Volatile generation Interferences Nafion membrane Electrochemical product generation Method comparison

"Continuous-flow Fluorimetric Determination Of Ammonia In Water"
Anal. Chem. 1983 Volume 55, Issue 9 Pages 1620-1622
Toyoaki Aoki, Satoshi Uemura, and Makoto Munemori

Abstract: Sample and phthalaldehyde reagent (prepared as described by Lindroth and Mopper, Ibid., 1979, 51, 1667) were separately pumped at 2.1 and 0.23 mL min-1, respectively, into a tubular micro-porous PTFE membrane separator (cf. Aoki and Munemori, Ibid., 1983, 55, 209).To liberate NH3 at the optimum pH of 13, 1 M NaOH was added to the sample stream at a point just in front of the separator. The liberated NH3 permeated the membrane and entered the reagent stream, buffered at pH 9.5, in the inner tube.T he reaction product was fed to the flow cell of a fluorimeter for detection at 486 nm (excitation at 370 nm). Water was flushed through the apparatus (and used to establish the blank value) after each sample. The fluorescence intensity was proportional to the concentration. of NH3 in the range 0.2 µM to 0.2 mM; the detection limit was 18 nM. A study was made of interferences. The recovery of NH3 added to river water ranged from 95 to 105%.
Ammonia Fluorescence Gas diffusion Interferences Teflon membrane

"Automated Determination Of Arsenic And Selenium By Atomic Absorption Spectrometry With Hydride Generation"
Anal. Chem. 1984 Volume 56, Issue 12 Pages 2059-2063
Hisatake Narasaki and Masahiko Ikeda

Abstract: Hydrides are evolved in a Pyrex mixing tube (15 cm x 2 mm), collected in a gas - liquid separator up to an appropriate pressure, and then swept automatically into an a.a.s. furnace. Consumption of reagents is minimized. Introduction of trace water into the furnace prevents any decrease in sensitivity. The sensitivities for As(V) and Se(IV) were 0.01 and 0.004 absorbance unit per ng, respectively. Recoveries were quantitative when samples were pre-treated with Chelex 100 resin to remove interfering species. Biological standard reference materials (decomposed initially by HNO3, H2SO4 and HClO4) and river water samples were analyzed for As and Se; the water samples taken were 25 to 50 mL and 250 to 500 ml, respectively.
Arsenic Selenium Spectrophotometry Chelex Interferences Reference material Phase separator

"Improved Online Stripping Voltammetry Using A Large-volume Wall-jet Detector"
Anal. Chem. 1985 Volume 57, Issue 8 Pages 1776-1778
Joseph Wang and Bassam A. Freiha

Abstract: The use of such a detector eliminates the need for de-aerating the sample and adding supporting electrolyte. The N is continuously passed into the solution in the detector compartment to provide the necessary inert atmosphere for the stripping step. Use of the detector is demonstrated with both flow injection and continuous-flow stripping systems by the determination of metals in a variety of samples, e.g., river water or organic solvents. In the measurement of Pb in water, a series of six successive additions of 0.1 µM-Pb gives a rectilinear plot; the coefficient of variation is 1.8% (n = 28) at the 0.25 µM level.
Lead Voltammetry

"Continuous-flow Two-point Titration System For Chloride Using A Pair Of Silver - Sulfide Ion-selective Electrodes"
Anal. Chem. 1986 Volume 58, Issue 7 Pages 1502-1506
Hirokazu Hara, Yoshiki Wakizaka, and Satoshi Okazaki

Abstract: The two-point titration principle was used, with addition of a small excess of AgNO3 [in 0.1 to 0.2 M KNO3 and containing 250 to 500 mg L-1 of poly(vinyl alcohol)] being followed by the second addition in a flow stream. The Cl- concentration. could be continuously estimated from the p.d. between a pair of silver - sulfide electrodes. The accuracy was within 2% and the precision was within 0.9% for 6 to 14 mg L-1 of Cl- (n = 5). The maximum error in river water samples containing 9.6 to 16.9 mg L-1 of Cl- was 1.8% when compared with the results from a batchwise titrimetric determination.
Chloride Electrode Electrode Potentiometry Titrations

"Gas Diffusion Unit With Tubular Microporous Poly(tetrafluoro-ethylene) Membrane For Flow Injection Determination Of Carbon Dioxide"
Anal. Chem. 1987 Volume 59, Issue 24 Pages 2930-2932
Shoji Motomizu, Kyoji Toei, Tohru Kuwaki, and Mitsuko Oshima

Abstract: A gas diffusion unit was constructed, without the use of glue, from two T-connectors linked by double tubing consisting of a micro-porous PTFE membrane inner tube (1 mm i.d. x 1.8 mm o.d.) and an outer PTFE tube (2 mm i.d.). The tubing was fixed to the connectors by a flange-type union. A carrier stream (0.8 mL min-1) of 0.18 M H2SO4 flowed through the outer tube and a cresol red color reagent solution (0.8 mL min-1) flowed through the inner tube. Standard solution (140 µL) of NaHCO3 and river water samples were injected into the carrier solution and absorbance changes were measured at 410 nm. Results agreed with those obtained by indirect photometric ion chromatography.
Carbon dioxide Spectrophotometry Apparatus Gas diffusion Teflon membrane

"Uranine-sensitized Chemiluminescence For Alternative Determinations Of Copper(II) And Free Cyanide By The Flow Injection Method"
Anal. Chem. 1989 Volume 61, Issue 14 Pages 1505-1510
Xing Zheng Wu, Masaaki Yamada, Toshiyuki Hobo, and Shigetaka Suzuki

Abstract: The chemiluminescence system Cu(II) - CN- - fluorescein (I) was applied in the determination of Cu(II) and free CN- by flow injection analysis with a single-flow system. The weak light emission produced by Cu(II) - CN- in the presence of dissolved O was effectively sensitized by I in aqueous propan-2-ol. Under optimum conditions, viz, 0.4 mM I, 50 µM CN- (for Cu mode) or 10 µM Cu(II) (for CN-), 80% propan-2-ol and a flow rate of 4 mL min-1, the determination limits were 6 and 5 pg for Cu(II) and CN-, respectively. The calibration graph was rectilinear over three orders of magnitude. The coefficient of variation (n = 10) was 3.1 and 3.3% for 30 nM Cu(II) and CN-, respectively. The method was applied in the analysis of tomato leaves and tap water for Cu and river water for CN-.
Copper(II) Cyanide, free Chemiluminescence Optimization

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

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

"Determination Of Rhenium And Platinum In Natural Waters And Sediments, And Iridium In Sediments By Flow Injection Isotope Dilution Inductively Coupled Plasma Mass Spectrometry"
Anal. Chem. 1993 Volume 65, Issue 10 Pages 1419-1425
Debra C. Colodner, Edward A. Boyle, and John M. Edmond

Abstract: Methods have been developed to measure Re, Ir, and Pt in natural waters and sediments by isotope dilution inductively coupled plasma mass spectrometry (ID-ICPMS). The techniques have been applied to determination of the three elements in sediments, Pt in seawater, and Re in seawater, sediment pore waters, and river waters. In each ease, a stable isotope-enriched spike is added to the sample before processing. Sediments are dissolved in all-Teflon digestion vessels using a modified standard kitchen microwave oven. Anion exchange of the chloro complexes of Ir and Pt and of the perrhenate ion (ReO4-) is used to pre-concentrate the elements and to separate them from concomitants which produce molecular ions in the argon plasma resulting in isobaric interferences. Samples are then introduced into the ICPMS in a small volume (300-600 mL) using flow injection. Overall recoveries were 90 10 for all three elements, although the effects of variable recovery efficiency were minimized by the isotope dilution The method has detection limits (3 times background) of approximately 5 pg of Re, 6 pg of Ir, and 14 pg of Pt. Copyright 1993, American Chemical Society. Isotope dilution ICP-MS was used to determine Re, Ir and Pt in water and sediments by adding a stable-isotope enriched spike. The isotopes were pre-concentrated and separated from species which produce molecular ions in the Ar plasma by anion exchange of the chloro complexes of Ir and Pt and of the ReO ion (details given). Biorad AG1-X8 (100-200 mesh) resin was used (chloride form). Flow injection was used to introduce samples (300-600 µL). Platinum and Ir were eluted with 12 M HNO3 at 90-100°C and Re was eluted with 8 M HNO3 at room temperature Recoveries were 90 ± 10% and detection limits were 5 pg for Re, 6 pg for Ir and 14 pg for Pt. Interference in the analysis of sediments from the oxides of the rare-earth elements and Hf was reduced to 5% by anion exchange. The RSD were 5% for Pt at the 1-10 ng/g level, 20% for Ir at the 0.01-0.1 ng/g level and 15% for Re at the 0.01-0.1 ng/g level in sediments. In seawater, the RSD were 15% for Pt at the 60 pg/kg level and 2% for Re at the 8 pg/kg level.
Rhenium Platinum Iridium Mass spectrometry Mass spectrometry Sample preparation Interferences Resin Biorad

"Ozone Gas-phase Chemiluminescence For Silane And Its Application To The Determination Of Silicate In Natural Waters"
Anal. Chem. 1993 Volume 65, Issue 14 Pages 1814-1818
Kitao Fujiwara, Masayuki Uchida, Min Min Chen, Yuichiro Kumamoto, and Takahiro Kumamaru

Abstract: Chemiluminescence emission generated by mixing silane with ozone was investigated for the determination of silicate in natural water. This chemiluminescence spectra extends 400-850 nm providing a maximum at 600 nm. Chemiluminescence spectra obtained by mixing diborane, and ozone were also shown. For the purpose of generating silane from the aqueous solution of silicate, the following procedure was adopted: The sample solution was dried and mixed homogeneously with powdered lithium aluminum hydride in a Teflon tube or a molybdenum boat. When this mixture was heated at 200-degrees-C, 97±3% of silicate in the sample was reduced to silane. After the generated silane was collected in the trap, the silane was mixed with ozone, and chemiluminescence was detected directly by a photomultiplier. The calibration curve was linear from 1 to 500 µg Si, and the detection limit was 0.5 µg of Si for this method. Phosphorus and arsenic give the positive interference, which is, however, negligible for the practical analysis of natural waters. The analytical results for river waters and seawaters (the Tokyo Bay and the North Pacific Ocean) are in good agreement with those confirmed by molybdenum yellow colorimetry. [References: 36]
Silicate Chemiluminescence Gas phase detection Interferences

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

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

"Flow Injection Techniques For Water Monitoring"
Anal. Chem. 1994 Volume 66, Issue 18 Pages 916A-922A
Kevin N. Andrew, Nicholas J. Blundell, David Price, Paul J. Worsfold

Abstract: The basic features of FIA that make it useful in laboratory and process analysis are outlined and its application to the in situ monitoring of natural and polluted waters is discussed. The instrumentation available for fresh water, marine and ground water monitoring is considered.
Spectrophotometry General Process monitoring Apparatus

"Determination Of Volatile Organic Compounds At The Parts Per Trillion Level In Complex Aqueous Matrices Using Membrane Introduction Mass Spectrometry"
Anal. Chem. 1994 Volume 66, Issue 24 Pages 4422-4431
Scott Bauer and David Solyom

Abstract: Recent advances in membrane introduction mass spectrometry (MIMS) have demonstrated the utility of MIMS in the trace level analysis of volatile organic compounds in water. The present study details the performance of an ion trap mass spectrometer fitted with a capillary membrane probe in the direct analysis of volatile organic compounds in water using flow injection techniques. Detection limits for 59 volatile organic compounds listed in EPA method 524.2 were determined to be in the mid to low parts per trillion (pptr) range using MIMS. Analyses of these compounds in untreated river water, seawater, and matrices containing strong acids and bases are demonstrated. The matrix studies show that there are no adverse effects on compound identification or detection limits resulting from matrix interferences in MIMS. Further experiments demonstrate the utility of MIMS as a direct analysis technique for online monitoring of trihalomethane formation in water treatment facilities. Detection limits of 100 pptr were obtained for the four trihalomethanes, with repetitive sample times averaging 6 min/sample. Quantitation of the total trihalomethane content was performed in one step, demonstrating further increases in analytical speed over traditional analysis methods. Copyright 1994, American Chemical Society.
Organic compounds Mass spectrometry Mass spectrometry PPT Interferences Membrane

"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

"Flow Injection Online Sorbent-extraction Preconcentration - Graphite-furnace Atomic Absorption Spectrometry: Trace-element Determination In The Ng L.minus.1 Range"
Fresenius J. Anal. Chem. 1990 Volume 337, Issue 1 Pages 135-136
Bernhard Welz, Michael Sperling, Zhaolun Fang

Abstract: A pre-concentration. system has been developed for graphite-furnace AAS and applied in the determination of Pb. It involves online formation of Pb diethyldithiocarbamate and its retention on a 15 µL conical column of C18-bonded silica. The detection limit was 3 ng L-1 of Pb, and the coefficient of variation (n = 11) at 0.1 µg L-1 was 1.9%. The method gave a 26-fold increase in peak area as compared with direct injection of the same volume of sample solution Results for sea- and river water standard reference materials agreed with the certified values.
Lead Spectrophotometry Sample preparation Preconcentration C18 Reference material Complexation Solid phase extraction

"Determination Of Lead In Natural Waters Using Flow Injection With Online Preconcentration And Flame AAS Detection"
Fresenius J. Anal. Chem. 1994 Volume 349, Issue 6 Pages 442-446
D. Rodr&iacute;guez, P. Fern&aacute;ndez, C. P&eacute;rez-Conde, A. Guti&eacute;rrez and C. C&aacute;mara

Abstract: Silica gel (0.063-0.2 mm) was coated with a chloroformic extract of the ion pair formed from Aliquat 336 (methyltricaprylammonium chloride) and nitroso-R-salt and the solvent was evaporated in vacuo. The product (118.3 mg) was packed in a glass column (5.5 cm x 3 mm i.d.). Water samples (5-30 ml) were mixed with 5% 0.1 M acetate buffer of pH 5.5 and were passed through the column at 1 ml/min. The retained Pb(II) was eluted with 0.15 mL of 0.1 M HCl at 2 ml/min directly to the nebulizer for analysis by AAS at 217 nm, with deuterium background correction. Calibration graphs were linear for 10^-100 ng/ml of Pb(II). Detection limits were 10, 6 and 4 ng/ml for 5, 10 and 30 mL samples, respectively. At 10 and 100 ng/ml of Pb(II), the RSD (n = 10) were 12 and 6%. The pre-concentration efficiency for 5 and 30 mL samples decreased from 100 to 50%; concentration factors were 37 and 100 times, respectively. Serious interferences were caused by Ni(II) and fluoride but these were not significant for natural waters. The results on samples of tap, ground and river water were similar to those obtained by electrothermal AAS.
Lead Spectrophotometry Interferences Preconcentration Silica gel Immobilized reagent

"Polar Organic Compounds In The River Elbe - Development Of Optimized Concentration Methods Using Substance-specific Detection Techniques"
Fresenius J. Anal. Chem. 1995 Volume 353, Issue 1 Pages 93-97
Horst Friedrich Schr&ouml;der

Abstract: Water was extracted by SPE on cartridges containing C18 or LiChrolut EN material with elution by methanol or selective elution with mixtures of organic solvents, or on XAD columns with desorption by hot steam extraction with methanol and ethyl acetate. The extracts were analyzed by LC-MS or FIA with thermospray ionization. LC was performed on a 5 µm nucleosil C18 column (25 cm x 4.6 mm i.d.) with gradient elution (1 ml/min) with acetonitrile and aqueous 20% methanol (details given) and thermospray ionization MS. For FIA by-passing the analytical column a mobile phase of aqueous 60% methanol and aqueous 0.1 M ammonium acetate (overall flow rate 1.5 ml/min) was used. The different extraction methods were compared and the results are discussed. There were little differences between the extraction methods for the adsorption of polar organic compounds.
Organic compounds LC Mass spectrometry

"Differential Determination Of Arsenic(III) And Total Arsenic With L-cysteine As Prereductant Using A Flow Injection Non-dispersive Atomic Absorption Device"
Fresenius J. Anal. Chem. 1996 Volume 355, Issue 3-4 Pages 324-326
X. Yin, E. Hoffmann and C. L&uuml;dke

Abstract: The reduction of 2 µg/l As(V) to As(III) was complete within 60, 40 or 20 min at L-cysteine concentrations of 0.04, 0.08 or 0.16M, respectively, at room temperature in 0.029 M HNO3 or 0.024 M HCl. After flow injection hydride generation, the sample was atomized in a quartz tube at 800°C for analysis using a non-dispersive AAS device. As was determined at 1 sample/min with a detection limit of 0.01 µg/l for a 0.5 mL sample. Of the other elements tested, only Se(IV) and Bi(III) interfered at 150-fold excess. The RSD was 1.2% (n = 10). The method was applied to the speciation of As in river, tap and mineral waters. The As(III) was determined directly in 0.166 M acetic acid and the total As by the above technique.
Arsenic Spectrophotometry Interferences Speciation

"Preconcentration Of Chromium(III) And Total Chromium In Waters For Flame AAS In A Flow-through Electrochemical/sorption Cell"
Fresenius J. Anal. Chem. 1996 Volume 355, Issue 5-6 Pages 528-531
E. Beinrohr, Alena Manov&aacute; and J&aacute;n Dzurov

Abstract: Water was adjusted to pH 7 and ionic strength 0.02 M and passed through a flow-through electrochemical cell containing activated alumina, with the electrodes off-circuited. The adsorbed Cr(III) was eluted with 1 M HCl and injected online for analysis using flame AAS. The cell contained a porous glassy C electrode coated with Au, a layer of sorbent and a counter electrode in series. Total Cr was determined by pumping the water through the cell while a constant current of -5 to -10 mA was applied. This reduced Cr(VI) to Cr(III) which was adsorbed together with the Cr(III) already present and analyzed as above. The method was applied to the analysis of tap, river and synthetic sea waters; detection limits were 0.5 and 250 ng/ml for 500 and 1 mL samples, respectively. Calibration graphs were linear from 0.5 ng/ml to 7.5 µg/ml Cr; RSD were 3-10%. Fe(III) did not interfere at concentrations 5 mg/l.
Chromium(III) Chromium, total Electrode Spectrophotometry Sample preparation Preconcentration Interferences Speciation Activated alumina

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

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

"Field Sampling Technique For Speciation Of Inorganic Chromium In Rivers"
Microchim. Acta 1992 Volume 109, Issue 1-4 Pages 161-164
A. G. Cox and Cameron W. McLeod

Abstract: The cited sampling technique was developed to collect and immediately pass water samples through microcolumns of activated alumina to isolate and retain Cr. This avoided problems associated with the stability and transportation of liquid samples. In the laboratory, the microcolumns were inserted into a flow injection ICP emission spectrometry system; Cr was detected at 267.6 nm.
Chromium(III) Chromium(VI) Spectrophotometry Speciation Activated alumina Preconcentration

"Evaluation Of Flow Injection In Lead Hydride Generation Atomic Absorption Spectrometry"
Microchim. Acta 1995 Volume 120, Issue 1-4 Pages 63-72
Yolanda Madrid, Dipankar Chakraborti and Carmen C&aacute;mara

Abstract: Three acid/oxidant systems were used to generate lead hydride for flow-through AAS determination of Pb, namely HNO3/H2O2, lactic acid/K2Cr2O7 and HNO3/ammonium persulfate (systems A, B, and C, respectively). Sample (500 µL) was injected into a stream of acid which merged with streams of oxidant and NaBH4, passed through a reaction coil and a gas-liquid separator and the lead hydride vapor was carried in Ar to the AAS system for determination of Pb at 217 nm using an air-acetylene flame. For system A the optimal reagent concentrations were 1% acid, 2% oxidant and 6% NaBH4. Corresponding figures for system B were 6%, 0.6% and 2% and those for system C were 2%, 3% and 6%. The reagent flow rate was 1 ml/min. Sensitivity was improved compared to the batch mode; detection limits were 0.8, 0.2 and 4 ng Pb for systems A, B and C, respectively. The corresponding RSD were 3%, 2.5% and 4% (n = 10). Characteristic masses are tabulated. Quantitation limits were 9, 5 and 18 µg/l, respectively (no other calibration data given). Interferences (tabulated) from As(III), Sb(III) and Hg(II), Cu and Ni were lower compared to the batch mode. The method was applied to sea, potable and river water; the results agreed with those obtained by GFAAS. The present study explores the attractiveness of combining flow injection (FI) with lead hydride generation atomic absorption spectrometry (AAS) to improve the selectivity and sensitivity of analysis. Lead hydride was generated in three acid-oxidant media: HNO3-(NH4)(2)S2O8, lactic acid-K2Cr2O7 and HNO3-H2O2. The effect of chemical parameters (acid-oxidant concentration and NaBH4 concentration) was investigated and the performance of each generation medium in terms of interferences, sensitivity and detection limits was compared with that obtained in batch mode. In all cases improved sensitivity (HNO3-H2O2, 0.8 ng Pb; lactic acid-K2Cr2O7, 0.2 ng Pb; (NH4)(2)S2O8-HNO3, 4 ng Pb) was obtained, most notably in HNO3-H2O2, which provided 12 times higher sensitivity than in batch mode and sharper absorption peaks. Furthermore, interference by Cu and Ni was lower in the proposed FI-HG system. Compared with the batch mode, about 10 to 100 times higher concentrations of interferent are tolerated in the sample. The use of FI also allows work at a lower NaBH4 concentration. The method was applied to the determination of lead in water samples with a sampling frequency of 180 samples per hour. In terms of both sensitivity and freedom from interferences, lactic acid-K2Cr2O7 was the best of the generation media tested. (13 references)
Lead Spectrophotometry Interferences Method comparison Optimization Volatile generation Volatile generation

"2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol As A New Analytical Reagent For Flow Injection Spectrophotometric Determination Of Trace Vanadium(V)"
Microchim. Acta 1998 Volume 130, Issue 1-2 Pages 111-115
Takeshi Yamane and Yuzuru Yamaguchi

Abstract: A flow injection method using 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol (Nitro-PAPS) as a new chromogenic reagent is presented for sensitive and rapid determination of V. Nitro-PAPS reacts with V(V) in weakly acidic medium to form a water soluble complex of molar absorptivity of 8.0 x 10^4 L mol-1 cm-1 at 592 nm (max. absorption wavelength), which permits the straightforward application of a flow injection system to the sensitive determination of vanadium. Under the optimum conditions established, a linear calibration graph was obtained in the range 1-120 ng mL-1. The RSD for 60 ng mL-1 V was 2.2% (n = 5) and the limit of detection was 1 ng mL-1. The sample throughput is ≈40 h-1. Most inorganic and organic anions examined did not interfere even at concentrations of 3000-6000 times of vanadium. Interference from Co(II), Cu(II), and Ni(II) at 200 ng mL-1 levels can be overcome by the addition of N-(dithiocarboxy)sarcosine. The recoveries for each 20 and 10 ng mL-1 V added to the river water were 98 and 97%, respectively.
Vanadium(V) Spectrophotometry Chromogenic reagent Optimization Interferences pH

"Solvatochromism Based On The Interaction Between Azo Dyes And Hydrophobic Ions: Application To The Determination Of Surfactants By Flow Injection Spectrophotometry"
Microchem. J. 1994 Volume 49, Issue 2-3 Pages 326-339
Motomizu S. and Gao Y. H.

Abstract: Aqueous solution of anionic surfactants (100 µL) were injected into a carrier stream (0.8 ml/min) of water which merged with a reagent stream (0.8 ml/min) of 40 µM propyl orange, 30 µM distearyldimethylammonium chloride and 0.02% Triton X-100 adjusted to pH 2.9 with monochloroacetate buffer. The solution were passed through a mixing acid (1 m x 0.5 mm i.d.) and the absorbance was measured at 510 nm. For the determination of quaternary ammonium ions and non-ionic surfactants, 40 µM butyl orange of pH 2.5 was used as the reagent solution with the absorbance being measured at 400 nm (positive peaks) or 510 nm (negative peaks). Details are given of detection limits and calibration graphs. The method was applied to the determination of anionic surfactants in river water.
Surfactants, anionic Spectrophotometry Triton X Surfactant

"Determination Of Vanadium By Its Catalytic Effect On The Oxidation Of Gallocyanine With Spectrophotometric Flow Injection Analysis"
Microchem. J. 1996 Volume 53, Issue 2 Pages 139-146
Ali A. Ensafi and A. Kazemzadeh

Abstract: Portions (200 µL) of standard V solutions were injected into a carrier stream of water at 0.5 ml/min delivered by a 12-channel peristaltic pump in a flow injection system (schematic shown). The sample-containing carrier stream was mixed sequentially with streams of 3.5 µM-gallocyanine (I) in a citrate buffer of pH 4 and 0.9 M NaBrO4 solution (both at 0.5 ml/min) in a 250 cm reaction coil. The decrease in the absorbance of I resulting from its V-catalyzed oxidation by bromate was measured at 620 nm. The calibration graph was linear from 0.01-100 ng/ml of V(V) [0.002-20 ng/200 µL solution] and the detection limit was 0.001 ng/200 µL. RSD (n = 10) were 3.2, 2, 1.7 and 1.1%, respectively, for 0.01, 0.1, 5 and 20 ng V(V). Tolerance levels for forty foreign ions and cations are listed. A throughput of 40 samples/h was achieved. The method was applied to the analysis of V(V) in human serum, crude petroleum and river water with recoveries of 100-105%.
Vanadium Spectrophotometry

"Flow Injection With An Integrated Retention/photometric Detection Unit For The Determination Of Iron In Water"
Microchem. J. 1996 Volume 53, Issue 4 Pages 413-419
Pablo Richter and M. In&eacute;s Toral

Abstract: An integrated retention/spectrophotometric detection flow injection method for the analysis of Fe in water samples, based on the temporary immobilization of the complex formed between the analyte [reduced to Fe(II)] and 3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine (ferrozine; I), is presented. Sample (2 ml) was injected into a carrier stream of water (0.6 ml/min) in a flow injection manifold (schematic shown) and merged with a reagent stream of 0.1% hydroxylamine in 0.2 M sodium acetate buffer flowing at the same rate. The analyte was reduced to Fe(II) in a mixing coil (50 cm x 0.5 mm i.d.) and reacted with a stream of I (0.8 ml/min) in a second coil (200 cm x 0.5 mm i.d.). The Fe(II)-I complex formed was adsorbed on a Dowex 1-X1 anion exchange resin packed in the flow cell of a photometric detector. The retention signal was measured at 575 nm. The calibration graph was linear from 10^-200 ng/ml of Fe and the detection limit (defined by the 3s criteria) was 4.3 ng/ml. RSD (n = 11) were 2.9, 1.3 and 2.1%, respectively, for 15, 100 and 180 ng/ml of Fe. Tolerance levels for the interference of eleven foreign ions on the determination of 25 ng/ml of Fe are tabulated. The method was applied to the analysis of tap and river water. Results were in good agreement with those obtained by AAS.
Iron Spectrophotometry Interferences

"Flow Injection Spectrophotometric Determination Of Hydrazine"
Microchem. J. 1997 Volume 56, Issue 3 Pages 269-275
Ali A. Ensafi and B. Naderi

Abstract: A three-line FIA manifold was used. The method was based on the decolorization of thionine by reaction with nitrite and its subsequent inhibition when trace amounts of hydrazine are present due to the reaction of hydrazine with nitrite in acidic media. A mixture of 0.1N-H2SO4 and 0.16 mM thionine solution, 4 µg/ml nitrite solution, and water were pumped at 0.5 ml/min. Sample (170 µL) containing 2-40 µg/ml of hydrazine was injected into the water carrier and the absorbance of thionine was measured at 602 nm. The method was optimized. The calibration graph was linear from 2-40 µg/ml of hydrazine with a detection limit of 1 µg/ml. The RSD (n = 10) was 3.3% for 7 µg/ml of hydrazine. The method was more selective than other kinetic and FIA methods and was applicable to river and drinking water; results are tabulated.
Hydrazine Spectrophotometry Detection limit Optimization Selectivity Method comparison Indirect

"Soluble And Particulate Metals In The Adige River"
Microchem. J. 1998 Volume 59, Issue 1 Pages 19-31
A. Bortoli, E. Dell'Andrea, M. Gerotto, M. Marchiori, M. Palonta and A. Troncon

Abstract: The concentrations of 10 metals (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) were monitored over a one-year period in the waters of the lower Adige River, Italy. Concentrations in the dissolved and particulate phases were measured, thus constructing a database on metal variability. The concentrations. of Cd, Cr, Cu, Mn, Ni, and Pb in these water samples are too low to be directly determined by flame atomic absorption spectrometry or graphite furnace atomic absorption spectrometry. In this work, Cd, Co, Cu, Mn, Ni, Pb, and Zn were determined by inductively coupled plasma mass spectrometry (ICP-MS) or GFAAS after online pre-concentration. and following solvent elution with a flow injection analysis system (FIAS). The eluted samples were also dried in a vacuum container and restored to a small volume with concentrated HNO3 and Milli-Q water for anal. by ICP-MS or GFAAS. The concentrations of soluble Cd, Fe, and Mn and particulate As, Cr, Cu, Pb, and Zn are well correlated with seasonal variability (P < 0.01). Dissolved As and Fe are well correlated (P < 0.01), and with respect to the particulate phase, good correlations are observed between Pb, Cd, and Cu.
Arsenic Cadmium Copper Chromium Cobalt Iron Manganese Nickel Lead Zinc Mass spectrometry Spectrophotometry Sample preparation Preconcentration Solvent extraction

"Flow Injection Analysis Using Potassium Permanganate: An Approach For Measuring Chemical Oxygen Demand In Organic Wastes And Waters"
Anal. Lett. 1980 Volume 13, Issue 11 Pages 1001-1011
Takashi Korenaga

Abstract: A rapid and continuous analytical method based on flow injection analysis was developed for the determination of COD due to organic substances in polluted water. The apparatus uses a double reciprocating micro-pump, a constant-volume sampling valve, a spectrophotometer, a recorder, and various lengths of polytetrafluoroethylene tubing. Potassium permanganate and sulfuric acid solutions were individually pumped up as oxidizing agents, and glucose was used as a standard substance. All samples were filtered with a 0.45 micron pore size membrane filter, and dissolved COD substances were measured. Municipal sewage, human wastes, and river water were examined, and COD values agreed with those obtained using the JIS method within the permissible error range of + or - 30%.
Chemical oxygen demand Spectrophotometry Method comparison

"Investigation Of A Chemiluminescent System For The Determination Of Ammonia By Flow Injection Analysis"
Anal. Lett. 1987 Volume 20, Issue 2 Pages 183-200
Kraus, P.R.;Crouch, S.R.

Abstract: The cited determination is based on the reaction of NH3 with HOCl to form NH2Cl, which then reacts with luminol and the chemiluminescence is monitored at 425 nm. A flow injection analysis system with chemiluminescence detector is described. Nearly all of the ions and compounds tested interfered but the effects could be minimized by use of a double-tube dialyser where the NH3 diffuses across the membrane into a stream of HCl. The method was used to determine NH3 in river water. Rectilinear calibration graphs were obtained for 100 to 1000 mM NH3.
Ammonia Chemiluminescence Dialysis Interferences

"Application Of Differential Pulse Anodic-stripping Voltammetry With A Stopped-flow System For The Simultaneous Determination Of Lead, Copper, Antimony And Bismuth In Environmental Samples"
Anal. Lett. 1994 Volume 27, Issue 9 Pages 1779-1787
Wang, F.Q.;Li, S.Y.;Lui, S.D.;Zhang, Y.;Liu, Z.

Abstract: River water (250 ml) was mixed with 10 mL of HNO3 and evaporated to ~10 mL. Additional 10 mL portions of HNO3 and HCl were added, the solution was evaporated to near dryness and the residues dissolved in 25 mL of 1 M HCl. The solution was pumped at 1.5 ml/min for 40 s through a 100 µL flow cell containing a Ag/AgCl reference electrode and a dropping-Hg electrode maintained at -0.5 V. A stripping solution of 0.25 M malonic acid in 1 M HCl was pumped through at 1.5 ml/min for 20 s at the same potential. The flow was stopped and anodic voltammetry performed. Calibration graphs were linear for 1-1000 nM-Cu, Sb, Bi and Pb. At 1 µM-Cu, 0.5 µM-Sb and Bi and 0.48 µM-Pb RSD of better than 0.5% were obtained with recoveries of 100±7% at 10 nM for each metal. Using a deposition time of 5 min, a detection limit of ~8 nM was obtained. Mn(II), Se(IV), Te(IV) and As(III) at a 10-fold excess and Cd, Zn, Ni, Al, In(III), Ti(I), Co(II), and Fe(III) at a 50-fold excess did not interfere.
Lead Copper Antimony Bismuth Voltammetry Electrode Interferences Stopped-flow

"Ultraviolet Determination Of Chloride In Water By Flow Injection Analysis"
Anal. Lett. 1996 Volume 29, Issue 5 Pages 793-806
Amin T. Haj-Hussein

Abstract: Water (50 µL) was aspirated into the sample loop via a syringe and injected into 0.01 M EDTA in acetate buffer of pH 4.6 as carrier stream (0.74 ml/min). The sample was merged with 1 mM Hg-EDTA reagent (0.74 ml/min) also buffered at pH 4.6 and passed through a 25 cm reaction coil. Detection was at 250 nm. The calibration graph was linear from 1.8-35.5 ppm chloride with a detection limit of 0.2 ppm. The sampling rate was 60 samples/h. The method was applied to tap, well, spring and river water. Recoveries ranged from 97.5-101.2%.
Chloride Spectrophotometry

"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

"Electrocatalytic Amperometric Detection Of Hydroxylamine With A Palladium-modified Carbon Paste Electrode"
Electroanalysis 1995 Volume 7, Issue 6 Pages 556-559
Xiaohua Cai, Kurt Kalcher, Josef Lintschinger, Christian G. Neuhold, Janusz Tykarski, Bozidar Ogorevc

Abstract: Carbon paste electrodes (CPEs), modified by addition of Pd powder to the paste and electroactivation, exhibited electrocatalytic activity towards hydroxylamine. Electrogenerated palladium(0) at the electrode surface was found to be involved in the electrocatalytic oxidation of NH2OH. The electrode was employed as an amperometric detector for flow injection systems. Repeated injections (60) of hydroxylamine (5 ng) showed a relative standard deviation of 4.0%. Linear relation between the current and the analyte concentration was found between 0.1 and 10 ng of hydroxylamine. The detection limit was 20 pg NH2OH (3). The applicability of the method to the determination of hydroxylamine in river water was investigated.
Hydroxylamine Amperometry Electrode Catalysis

"Preconcentration Of Divalent Trace Metals On Chelating Silicas Followed By Online Ion Chromatography"
J. Chromatogr. A 1991 Volume 541, Issue 1-2 Pages 443-452
D. Chambaz, P. Edder and W. Haerdi

Abstract: For online pre-concentration of the cited metals, a titanium pre-column (1.3 cm x 1.7 mm or 5 cm x 2 mm) of ethylenediamine triacetate-bonded silica (prep. described) was used, with adsorption from a mobile phase of 0.1 M acetate buffer (pH 5.0) and desorption with 0.1 M HNO3. The eluate was adjusted to pH 3.0 with 0.5 M tartaric acid for use as mobile phase for HPLC on a column (30 cm x 4 mm) of Nucleosil 10SA with post-column derivatization with 4-(2-pyridylazo)resorcinol in a PTFE coil (3 m x 0.5 mm) and detection at 500 nm. Calibration graphs for Co, Ni, Cu, Zn, Cd and Pb were rectilinear from 3 nM to 3 µM; the method was applied to river water.
Cadmium Cobalt Copper Lead Nickel Zinc HPIC Spectrophotometry Buffer pH Post-column derivatization Column Preconcentration Chelation

"Polar Organic Pollutants In The Elbe River. Liquid Chromatographic - Mass-spectrometric And Flow Injection Analysis - Mass-spectrometric Analyses Demonstrating Changes In Quality And Concentration During The Unification Process In Germany"
J. Chromatogr. A 1995 Volume 712, Issue 1 Pages 123-140
Horst Fr. Schr&ouml;der

Abstract: Pollution of the River Elbe was monitored during the period 1989-1994. Water samples were treated by liquid-liquid extraction with hexane or SPE using C18, XAD-2 or XAD-4 columns. The extracts were analyzed by various techniques including capillary GC-MS, LC-UV, LC-MS and FIA-MS/tandem MS. The accumulative results, illustrated by representative examples, revealed a reduction in the amount of pollutants present with a concomitant change of composition. The changes observed were explained by reduced industrial production in the former GDR and the construction of biological sewage treatment plants. During the unification process of the two German states from 1989 to 1994, water extracts from the Elbe river were analyzed by gas chromatography-mass spectrometry (GC-MS) and by high performance liquid chromatography (HPLC) combined with ultraviolet (UV) and/or mass spectrometric detection (MS) in order to monitor the pollutants in one of the most contaminated European rivers. After column chromatography (LC) or flow injection analysis bypassing the analytical column, ionization was performed by a thermospray interface (TSP). Semiquantitative estimations of the pollution of the Elbe were made from the total-ion current traces (TIC) of the extracts. Determination of the total dissolved organic carbon (DOC) indicated a reduction of more than 55% of pollutants in the water phase. The pollutants were identified by tandem mass spectrometry (MS-MS), generating daughter-ion spectra by collision-induced dissociation (CID) using either column chromatography or direct mixture analysis. Compound-specific analyzes indicated a reduction in the amount of pollutants as well as a change in their composition. This could be explained by reduced industrial production and by intensified construction of biological sewage treatment plants.
Organic compounds HPLC Mass spectrometry

"Analysis Of Polar Organic Pollutants In The Elbe River By Flow Injection Analysis And High Performance Liquid Chromatography With Tandem Mass Spectrometry"
J. Chromatogr. A 1997 Volume 777, Issue 1 Pages 127-139
Horst Fr. Schr&ouml;der

Abstract: Water extracts from the Elbe river and from one of its tributaries have been analyzed by gas chromatography-mass spectrometry (GC-MS) and by high performance liquid chromatography combined with ultraviolet (UV) and/or MS detection. After column chromatography or flow injection analysis (FIA) bypassing the analytical column, ionization for MS was performed by either atmospheric pressure chemical ionization or electrospray. Since the reduction of the pollutant concentrations relative to the concentration of matrix components in the water samples had continued compared to earlier investigations [H.Fr. Schroder, J. Chromatogr. A 712 (1995) 123-140], substance-group-specific methods were applied for the screening for certain compound groups. For this purpose tandem mass spectrometry (MS-MS) was used to characterize the substance groups, with the help of parent-ion and neutral-loss scans. Identification then followed by means of daughter-ion spectra, which were generated by collisionally induced dissociation (CID) using FIA-MS- MS. The limitations of mixture analysis in the case of isomeric compounds present in the extracts are demonstrated.
Organic compounds Mass spectrometry HPLC

"Investigations Into Mild Conditions For Reduction Of Selenium(VI) To Selenium (IV) And For Hydride Generation In Determination Of Selenium By Direct-current-plasma Atomic-emission Spectrometry"
Spectrochim. Acta B 1997 Volume 52, Issue 2 Pages 163-176
Ian D. Brindle* and Emilia Lugowska

Abstract: Bromide reduces Se(VI) rapidly in acid solution. Prereduction of Se(VI) by boiling for 14 min in 1.4 M KBr/0.48 M HCl gave equivalent results for the determination of Se in river water to those obtained by boiling for 9 min in 5 M HCl. The influence of the relative concentrations of H+, bromide and chloride on the reduction is discussed, and it is conjectured that it might be possible to eliminate the prereduction as a separate step and to reduce to Se(VI) online in a flow injection system.
Selenium(VI) Selenium(IV) Spectrophotometry Sample preparation Speciation Optimization

"Determination Of Arsenic, Antimony, Bismuth And Mercury In Water Samples By Flow Injection Inductively Coupled Plasma Mass Spectrometry With An In Situ Nebulizer/hydride Generator"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1813-1821
Chih-Shyue Chen and Shiuh-Jen Jiang*

Abstract: The sample (0.2 mL) is injected into a stream (1 mL/min) of 0.5% cysteine solution in 0.05 M HNO3 that then merges with a stream (1 mL/min) of 0.2% NaBH4 solution in 0.02 M NaOH. The combined streams then pass to a crossflow pneumatic nebulizer with a Scott-type spray chamber for introduction into the ICP of an ELAN 5000 ICP-MS instrument; at the instrument settings tabulated, one data point could be recorded per s. Either the height or area of the flow injection peak could be used as the signal; calibration graphs based on peak heights were linear for 0.1-10 ng/mL of the cited elements, and the detection limits were 3, 17, 3 and 170 pg/mL, respectively. Both direct calibration and the method of standard additions gave satisfactory results for tap water, but for river and seawater use of the method of standard additions was necessary; for seawater it was also necessary to correct for the interference from 40Ar35Cl+ with the determination of 75As+ (equation given).
Antimony Arsenic Bismuth Mercury Mass spectrometry Interferences Standard additions calibration Volatile generation Volatile generation

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

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

"Determination Of Manganese At Trace Levels In Natural Waters With Continuous-flow System Utilizing Online Cation-exchange Separation And Catalytic Detection"
Anal. Sci. 1986 Volume 2, Issue 2 Pages 191-195

Abstract: The filtered (0.45 µm, Millipore) sample is made ~0.06 M in HCl and passed through a column of Hitachi Custom Resin No. 2611 (15.5 µm; strong cation exchanger), from which Mn is eluted with 0.2 M Na tartrate - 6 mM tartaric acid - 0.32 M NaCl (pH 5.1). Streams of 52 mM 3,4-dihydroxybenzoic acid (I), 1.5% H2O2 solution and 1.0 M Na2CO3 are pre-mixed in a coil, then mixed in a reaction coil (5 m long) with the Mn-containing eluate. The increase in absorbance at 480 nm, due to the Mn-catalyzed oxidation of I, is recorded. The detection limit with use of a 906 µL sample loop is 0.2 ng mL-1. For river and lake waters containing 1.4 to 11.2 ng mL-1 of Mn, the coefficient of variation was <2.5% (n = 5 or 6). The method shows good selectivity.
Manganese Ion exchange Spectrophotometry Catalysis Column Resin Optimization

"Flow Injection Spectrophotometric Determination Of Trace Amounts Of Iron With 2-pyridyl-3'-sulfophenylmethanone-2 Pyrimidylhydrazone And Possibility Of Sensitization By Analogue Derivative Spectrophotometric Monitoring"
Anal. Sci. 1986 Volume 2, Issue 2 Pages 125-129

Abstract: The reaction reported by Aita et al. (Anal. Abstr., 1985, 47, 4B134) has been applied to the flow injection determination of traces of Fe in water. The fourth derivative of the absorbance is measured at 580 nm to provide high selectivity, and mercaptoacetate is used as reducing and masking agent. Ascorbic acid can be used as reducing agent if masking is not required. Water samples (1 l) are initially evaporated to dryness with 1 mL each of 1 M HCl and 0.5 M H2SO4, and the residue is dissolved in 0.1 M HCl and appropriately diluted before analysis. The limit of determination is 10 ppb and the response is rectilinear up to 210 ppb.
Iron Spectrophotometry Optimization Method comparison

"Determination Of Potassium In River Water By Solvent Extraction Flow Injection Analysis"
Anal. Sci. 1986 Volume 2, Issue 5 Pages 493-494

Abstract: The flow injection system is described and illustrated. The sample was injected into water carrier and mixed with 0.5 mM tropaeolin OO (C. I. Acid Orange 5) - 3 mM LiOH - 1 mM Li2EDTA. This solution was then mixed with 4 mM dibenzo-18-crown-6 in benzene and passed through a coil (1 m x 0.5 mm). A PTFE membrane (pore size 0.8 µm) separated the phases, and the absorbance of the organic phase was measured at 430 nm. The calibration graph was rectilinear up to 0.1 mM K. Large concentration. of Na interfered slightly.
Potassium Spectrophotometry Sample preparation Interferences Organic phase detection Teflon membrane Solvent extraction

"Spectrophotometric Determination Of Anionic Surfactants In River Water With Cationic Azo Dye By Solvent Extraction-flow Injection Analysis"
Anal. Sci. 1987 Volume 3, Issue 3 Pages 265-269

Abstract: The extraction - flow injection analysis system used is described (with diagrams). Sample solution was injected into the carrier stream (H2O) and mixed with a stream containing 50 µM-1-alkyl-4-(4-dialkylaminophenylazo)pyridinium salt (6 azo-dyes examined), 1 mM EDTA, 0.1 M Na2SO4 and 0.1 M acetate buffer (pH 5). The resulting stream was mixed with extracting solvent (various) and passed through a PTFE membrane (0.8 µm pore size) phase separator. The absorbance of the organic phase was measured at 564 nm. The detection limit was 10 nM of anion surfactant and the calibration graph was rectilinear up to 2 and 30 µM, for 300- and 100 µL injected, respectively. The coefficient of variation (n = 10) was 1.5% for a 300 µL injection of 1 µM-Na dodecyl sulfate. The method was applied in the determination of anionic surfactants in river water.
Surfactants, anionic Spectrophotometry Sample preparation Solvent extraction Phase separator Teflon membrane

"Flow Injection Spectrophotometric Determination Of Trace Amounts Of Bromide By Its Catalytic Effect On The Hydrogen Peroxide Oxidation Of Pyrocatechol Violet"
Anal. Sci. 1988 Volume 4, Issue 3 Pages 273-276

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

"Spectrophotometric Determination Of Calcium With Dicyclohexano-24 Crown-8 And Propyl Orange By Solvent Extraction/flow Injection Method"
Anal. Sci. 1990 Volume 6, Issue 2 Pages 215-220

Abstract: The optimum conditions for the cited determination (flow diagram of apparatus given) were: an injection volume of 100 µL; water as carrier stream (0.8 mL min-1); 0.5 mM propyl organge - 0.1 mM LiOH as reagent solution (0.8 mL min-1); 2 mM dicyclohexano-24-crown-8 in benzene - chlorobenzene (1:1) as extractant; a PTFE extraction coil (2 m x 0.5 mm) and detection at 420 nm. The calibration graph was rectilinear up to 0.1 mM Ca and the detection limit was 0.2 µM. The coefficient of variation was 1% at 50 µM-Ca. Results for determination of Ca in river water agreed well with those by EDTA titration. The system can be applied in the determination of Sr and Ba if interference by Ca is accounted for.
Calcium Spectrophotometry Sample preparation Optimization Calibration Detection limit Interferences Method comparison Solvent extraction

"Flow Injection Extraction-spectrophotometric Determination Of Copper With Dithiocarbamates"
Anal. Sci. 1990 Volume 6, Issue 3 Pages 415-420

Abstract: Several dithiocarbamates were investigated as reagents for the determination of Cu, and a flow injection method was developed. Sample solution (300 µL) in aqueous NH3 buffer (pH 8.5) as carrier solution was mixed with 0.05% Pb diethyldithiocarbamate in CHCl3, and passed through a coil (400 cm x 0.5 mm). The phases were separated in a membrane separator, and the absorbance of the organic phase was measured at 436 nm. The detection limit is 0.04 ppm of Cu, and the calibration graph is rectilinear up to 2 ppm. The method was applied to water and plants; results were precise and accurate.
Copper Spectrophotometry Sample preparation Extraction Buffer pH Mixing Membrane Organic phase detection Detection limit Calibration

"Batchwise And Flow Injection Methods For The Spectrophotometric Determination Of Anionic Surfactants With 4-(4-N,N-dimethyl-aminophenylazo)-2-methylquinoline"
Anal. Sci. 1990 Volume 6, Issue 5 Pages 705-710

Abstract: River water (100 ml) was diluted to 100 mL with water, and mixed with 0.5 mL of 10 M H2SO4 and 1 mL of 0.1 M ascorbic acid (reducing agent, if necessary). The mixture was extracted with 5 mL of 25 µM-4-(4-dimethylaminophenylazo)-2-methylquinoline (I) in CHCl3, and the absorbance of the organic phase was measured at 560 nm (ε = 45,000). Up to a 40-fold concentration. was possible. With 20-fold concentration, the calibration graph was rectilinear for 0.01 to 0.75 µM-anionic surfactants. The coefficient of variation (n = 10) for 0.5 µM was 0.3%. Ions normally present in river water did not interfere. The spectrophotometric method was applied to a flow injection method; results were much higher than those by the batch method. I could be recycled and was used for 7 months without loss of efficiency.
Surfactants, anionic Spectrophotometry Sample preparation Solvent extraction Interferences Method comparison Organic phase detection

"Selective Determination Of Inorganic And Total Mercury By Cold Vapor Atomic Fluorescence Spectrometry Coupled With Flow Injection Analysis"
Anal. Sci. 1990 Volume 6, Issue 1 Pages 91-95

Abstract: An aqueous sample (0.6 ml), containing 0.5 to 20 ppb of Hg(II), is injected into a stream of 0.5 M H2SO4. Organomercury compounds, e.g., methylmercury chloride, are irradiated in a flow system for 1.5 min in 0.05 M H2SO4 with a 400-W UV lamp before sample injection. The Hg(II) is reduced to elemental Hg with SnCl2 solution (1 to 10%) in 0.5 M H2SO4, and the Hg is separated by passage through PTFE tubing counter-current to a flow of Ar in an outer tube. Any water in the Ar is removed by condensation at -5°C and Hg is determined by AFS in a special cell with irradiation at 253.7 nm and measurement with a solar-blind photomultiplier. The limit of detection is 0.18 ppb of Hg is reported. Of the substances tested only cysteine interferes in the determination of total Hg probably via decomposition to S2-. The coefficient of variation were 2% (n = 10). The sampling rate was 20 h-1.
Mercury Methylmercury ion Fluorescence PPB Detection limit Interferences UV reactor Photochemistry

"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

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

"Determination Of Arsenic And Selenium In River Water By Hydride-generation Inductively Coupled Plasma Mass Spectrometry With High Resolution"
Anal. Sci. 1996 Volume 12, Issue 4 Pages 623-627

Abstract: A hydride-generation flow injection ICP-MS method for the determination of As and Se in river water is presented. For As, 100 mL water was boiled for 5 min with 1 mL concentrated HNO3, the pH was adjusted to 3.5 and the solution was applied to a Chelex 100 chelating resin. For Se, 100 mL water was boiled for 5 min with 2 mL concentrated HCl and the solution was applied to a chelex resin as above after pH adjustment. Both column eluate were diluted with water until the acidity became 0.1 M. Each sample was transferred in turn to the hydride generation system (schematic shown). Variable speed peristaltic pumps were used to mix sample solutions with 0.2% sodium tetrahydroborate(III) solution (both at 1 mL/min) in a Pyrex mixing coil (15 cm x 2 mm i.d.). The hydrides generated were swept continuously into the ICP torch (operating parameters given) and As and Se were detected by the MS operating at a resolution of 10,000 in selected-ion monitoring mode at m/z 75 and 82, respectively. Using standard solutions, the detection limits were 0.03 and 0.06 ng/ml, respectively, for As and Se. Interference levels of foreign ions on the determination of As and Se are listed. Results (tabulated) obtained the elements in NIST reference materials agreed with certified values. The concentration levels of As and Se in Japanese rivers close to industrial production sites were in the range 1.62-3.77 and 0.07-0.48 ng/mL, respectively.
Arsenic Selenium Mass spectrometry Interferences Reference material Chelex Resin

"Determination Of Major And Trace-elements For Certified Reference Material Of Riverine Water JAC-0031 And JAC-0032 By ICP-MS"
Anal. Sci. 1997 Volume 13, Issue 2 Pages 177-182

Abstract: Element concentrations were determined by ICP-MS for certified reference materials of riverine water JAC 0031 and JAC 0032 which were recently distributed for a collaborative study to determine certified values. Concentrations were determined of nine elements (Mg, Al, Mn, Ni, Cu, Zn, As, Cd and Pb) out of sixteen elements, which were intended to be certified. An additional eleven trace elements (Li, V, Co, Rb, Sr, Mo, Sb, Cs, Pa, W and U) were also determined. The results obtained for the former nine elements generally agreed well with the values from other laboratories and with certified values. The results obtained for the latter eleven elements were consistent with our previous data, which were obtained from our monitoring project for the same river at a nearby sampling point. 39 References
Magnesium Aluminum Manganese Nickel Copper Zinc Arsenic Cadmium Lead Lithium Vanadium Cobalt Rubidium Strontium Molybdenum Antimony Cesium Palladium Tungsten Uranium Mass spectrometry Reference material Method comparison

"Online Photo-oxidative Decomposition Of Phosphorus Compounds To Orthophosphate And Its Application To Flow Injection Spectrophotometric Determinations Of Total Phosphorus In River And Waste Waters"
Anal. Sci. 1998 Volume 14, Issue 5 Pages 941-946
Keiro HIGUCHI), Hiromitsu TAMANOUCHI) and Shoji MOTOMIZU

Abstract: A simple and mild online photo-oxidative decomposition method for the highly sensitive flow injection spectrophotometric determination of total P in river water and wastewater was developed using low pressure mercury lamps. Organic and inorganic P compounds in sample solutions were injected into a carrier solution, which merged with the decomposition solution containing sulfuric acid and K peroxodisulfate. The solution components were decomposed oxidatively to orthophosphate while flowing in a photo-reactor. After the decomposition, orthophosphate was determined spectrophotometrically based on the formation of Molybdenum Blue. The photo-reactor consisted of two low pressure mercury lamps, a poly(terafluoroethylene) (PTFE) tubing and a reflection mirror. The PTFE tubing was wound directly around the Hg lamps, which were covered with reflection mirror. The detection limit for P was ~0.001 mg/L, and the sample throughput was ~20 samples/h for total P determination Using the photo-reactor, most of the P compounds were decomposed completely, whereas some condensed phosphates were less susceptible to photo-oxidation. The analytical results for practical samples obtained by the proposed method showed a good correlation with those obtained by using a heat-oxidation method, which indicates that the content of the condensed phosphates difficult to be decomposed was very scarce in the practical samples.
Phosphorus Spectrophotometry Photochemistry UV reactor Method comparison

"Determination Of Dissolved Humic Substances In River Water Using Flow Injection Analysis With Fluorimetric Detection"
Anal. Proc. 1986 Volume 23, Issue 8 Pages 307-308
W. A. McCrum

Abstract: The method involves use of a mixed reagent (cf. Brun and Milburn, Anal. Abstr., 1978, 35, 3H46) of sodium borate buffer (pH 10.5) and citrate - tartrate solution, with fluorimetric detection at 460 nm (excitation at 270 nm). The procedure is automated with a Tecator type 1 manifold, and can examine ~105 samples h-1, containing 0.3 to 20 mg L-1 of humic acid.
Acids, humic Fluorescence Tecator

"Simultaneous Determination Of Hydride And Non-hydride Forming Elements By Inductively Coupled Plasma Atomic-emission Spectrometry"
Anal. Proc. 1992 Volume 29, Issue 10 Pages 438-439
Zhang Li, Susan McIntosh and Walter Slavin

Abstract: Arsenic, Se, Sb, Bi, Cd, Cr, Cu, Fe, Mn, Ni and Pb were determined in the NIST environmental standard reference materials steel, coal fly ash, urban particulated and 1643b water by ICP-AES. A Perkin-Elmer FIAS-2000 flow injection system was used for hydride generation (experimental conditions tabulated). The sample solution was split into two streams, one being pumped directly to the nebulizer, the other mixed with HCl and NaBH4 solution in the mixing tubes of the chemifold. After separation, the hydride was swept into the spray chamber through a slightly modified cross-flow nebulizer cap. The hydride was then carried into the plasma together with sample aerosol. Recoveries of 20 µg L-1 of As, Sb and Se and 50 µg L-1 of non-hydride forming elements in river- and seawater standards were >80%.
Arsenic Selenium Antimony Bismuth Cadmium Chromium Copper Iron Manganese Nickel Lead Spectrophotometry Spectrophotometry Reference material FIAS-200 Nebulizer Volatile generation Volatile generation

"The Fate Of Mercury Released From Prospecting Areas ('garimpos') Near Guarinos And Pilar De Goias (Brazil)"
An. Acad. Bras. Cienc. 1988 Volume 60, Issue 3 Pages 293-304
Choudhuri A.

Abstract: Analyses have been made of river water and of sediment up to 1500 m downstream to permit tracing of the mercury released from gold prospecting sites located in the State of Goias (Brazil). The determinations were performed by atomic emission spectroscopy coupled to a flow injection analysis system, operated in the reverse-FIA (r-FIA) configuration, and using either SnCl-2 or NaBH-4 as reducing agents. Mercury seems to be preferencially deposited in the sediment in specific points within 100 m of the site where the slip is discharged into the river drainage. The level of dissolved mercury in the river water was independent of the mercury content of the sediment and is in the range of 1.85 to 4.45 ng mL-1. According to these data, the principal environmental hazard from the amalgamation processing of gold appears to be due to mercury vapor released during the flaming process.
Mercury Spectrophotometry Amalgamation Reverse

"Continuous-flow Determination Of Nitrite With Membrane Separation Chemiluminescence Detection"
Biomed. Chromatogr. 1990 Volume 4, Issue 3 Pages 128-130
Toyoaki Aoki

Abstract: Sample is mixed with 1 M KI solution followed by 0.18 M H2SO4. The mixture is driven (8 mL min-1) through a separation unit (60 cm in length) comprising an outer PTFE tube (4 mm i.d.) and an inner microporous PTFE tube (2.8 mm o.d.; 2.0 mm i.d.; max. pore size 3.5 µm). Nitric oxide produced permeates through the microporous PTFE into a stream of clean air (600 mL min-1) in the inner tube and, after removal of water vapor with use of a Nafion permeation tube system, NO is determined chemiluminometrically by its reaction with ozone. The calibration graph was rectilinear from 10 ppb to 5 ppm of nitrite in water and the coefficient of variation (n = 5) at 0.1 ppm was 0.7%. Results for the determination of I in river water agreed well with those obtained by the NED method.
Nitrite Chemiluminescence Nafion membrane Method comparison Permeation tube Teflon membrane

"Spectrophotometric Determination Of Silicic Acid By Flow Injection Analysis"
Bull. Chem. Soc. Jpn. 1982 Volume 55, Issue 11 Pages 3477-3481
Takushi Yokoyama,Yukio Hirai,Norimasa Yoza,Toshikazu Tarutani and Shigeru Ohashi

Abstract: Flow injection analysis (FIA) was developed for the spectrophotometric determination of silicic acid based on the formation of a yellow molybdosilicic acid (yellow method) and a heteropoly blue complex (blue method). In the yellow method, silicic acid in the concentration range of 2 to 100 ppm (SiO2) could be determined at a sampling rate of 60 samples/h. The FIA system was modified to determine silicic acid in the presence of orthophosphate. Oxalic acid was used for the decomposition of molybdophosphoric acid. The modified system was employed for the rapid and selective determination of silicic acid in well and river waters. In the blue method, ascorbic acid was used to reduce the yellow molybdosilicic acid to a heteropoly blue complex. Silicic acid in the concentration range of 0.02 to 1.0 ppm (SiO2) could be determined at a sampling rate of 40 samples/h. The FIA system was also modified to determine silicic acid in the presence of orthophosphate. The reducing agent was introduced after molybdophosphoric acid had been completely decomposed by adding oxalic acid. The modified system was employed for the determination of silicic acid in sea water.
Silicic acid Spectrophotometry Interferences Heated reaction

"Determination Of Fluoride Ion By Flow Injection Analysis Based On The Formation Of A Fluorescent Aluminum - Schiff Base Complex"
Bull. Chem. Soc. Jpn. 1992 Volume 65, Issue 3 Pages 911-913
Izuo Aoki, Masahiko Tuyuki and Kunihiro Watanabe

Abstract: A flow injection procedure based on the reaction of Al and N-salicylidene-ethylenediamine in the presence of F- was developed to determine ppm levels of F- ions. The fluorescence intensity of the Schiff base complex formed was measured at 460 nm (excitation at 360 nm). The F- concentration. could be selectivity determined over the range 0.15 to 10 ppm with a coefficient of variation of 3%. The detection limit was 0.05 ppm and sample throughput was 40 h-1. Oxalate, tartrate and phosphate interfered. The method was successfully used to determine F- in river water. In the presence of fluoride ions, aluminum reacts with N-salicylideneethylenediamine to form fluorescent Schiff base complexes. A flow injection analysis system based on this reaction has been developed for a determination of the fluoride ions at the ppm level. By measuring the fluorescence intensities, fluoride ions could be selectively determined over the range 0.15-10 ppm; 40 samples could be analyzed per h. The proposed system was applied to the determination of fluoride in river water.
Fluoride Fluorescence Indirect Complexation Interferences

"Flow Injection Analysis Of Phosphates In Environmental Waters"
Bunseki Kagaku 1981 Volume 30, Issue 7 Pages 465-469
Yukio HIRAI, Norimasa YOZA, Shigeru OHASHI

Abstract: High-pressure flow injection system developed for the determination of ortho- and polyphosphates was applied to the rapid analysis of phosphates in various environmental waters. A strongly acidic molybdenum (V) and molybdenum(VI) reagent was used so that hydrolysis of polyphosphates and color development of the resultant orthophosphate could be achieved simultaneously. A sample solution (0.5 ml) was introduced into a carrier stream of water via a loopvalve sample injector. The carrier stream meets a molybdenum reagent stream from another channel and flows together into a reaction tubing. For complete chemical reaction, the temperature of the reaction tubing (PTFE, 0.5 mm i.d., 1.5 mm o.d., 30 m) was maintained at 140°C. Residence time of the sample in the reaction tubing was about 4 min. The absorbance of heteropoly blue complex was monitored. at 830 nm. Sampling rate was 30 samples/h. Detection limit was 3 x 10^-7 M (0.010 ppm P). The precisions (C.V.) were 4.0 %, 0.3 % and 0.2 % for orthophosphate of 1 x 10^-6 M, 1 x 10^-5 M and 1 x 10^-4 M, respectively. It was found that the flow injection system was effective in determining phosphate in river and well water, but the concentrations of phosphate in sea water and tap water were too low to be monitored by the present system.
Phosphate Polyphosphates Spectrophotometry Heated reaction

"Flow Injection Analysis System With Personal Computer: Application To A Fully Automated Method For The Measurement Of Dissolved Chemical Oxygen Demand In River Waters"
Bunseki Kagaku 1982 Volume 31, Issue 9 Pages 517-523
Takashi KORENAGA, Hisayoshi IKATSU

Abstract: A useful and sensitive system has been developed for the fully automated flow injection analysis by connecting a cheap commercial personal computer. The system has successfully been applied to continuously measure the µamount of chemical oxygen demand (COD) in river waters. Both a potassium dichromatesulfuric acid solution and water are separately pumped up with a double reciprocating micro-pump. A 500 µl sample is injected into the flow of water with an automatic sample injector, and the solutions are merged into a carrier stream. The COD substances in samples are oxidized by dichromate for 20 min in a reaction manifold, made of poly (tetrafluoroethylene) tubing (0.5 mm i.d. x 50 m) and heated at 120°C. The resulting solution is led into a spectrophotometric detection at 445 nm. COD values are automatically measured with this computer system by directly analyzing absorbance data, obtained via an interface unit having an analog/digital converter from the spectrophotometer. The BASIC can easily be used for computer programing. D-Glucose was used as a standard substance for calibration curves using peak heights or peak areas. A sampling rate of 10 samples h-1 could be achieved, and the detection limit and precision were 0.5 mg L-1 and 2%, respectively. For river water samples at a COD level of (12) mg L-1, COD values obtained from peak heights were comparable to those obtained with the Japanese standard method.
Chemical oxygen demand Spectrophotometry Computer Method comparison Heated reaction

"Flow Injection Analysis Of Trace Amounts Of Iodide Ion Using A Catalytic Method"
Bunseki Kagaku 1983 Volume 32, Issue 1 Pages 23-28

Abstract: A sensitive, rapid, and simple method has been developed for the determination of trace amounts of iodide ion by means of flow injection analysis based on the catalytic reduction of sulfatocerium(IV) ion by arsenic trioxide in sulfuric acid. A sample solution was injected into a redistilled water stream which flowed together with the pre-mixed cerium(IV) and arsenic trioxide in sulfuric acid solution. The sample in the reagent stream was first heated to 60°C to promote the reaction and then cooled to 20°C before being passed into a flow cell. The detection is based on a discoloration of the trisulfatocerium(IV) complex at 312 nm by spectrophotometer equipped with the flow cell(volume 8 µl, light path 10 mm). The optimal conditions were as follows; cerium(IV) : 1.30 x 10^-3 M in 1.00 M sulfuric acid (flow rate, 1.06 ml/min), arsenic trioxide: 2.40 x 10^-2 M in 1.00 M sulfuric acid (flow rate, 1.07 ml/min), flow rate of redistilled water: 4.22 ml/min, reaction time: 0.67 min, reagent mixing tube: 180 cm (0.2 cm i. d.), heating tube: 136 cm (0.2 cm i. d.), cooling tube: 67 cm (0.2 cm i. d.), sample volume: 2.69 mL. A linear relationship was obtained between the peak height (absorbance change based on a discoloration) and concentration of iodide ion in the range of 050 ppb. The detection limit (S/N: 2) was 1 ppb iodide ion. The sampling rate was 30 samples/h. The reactivity of the sulfatocerium(IV) complexes varied with the number of ligands. The trisulfato complex showed a remarkable catalytic reactivity, whereas the monosulfato complex showed no obvious reactivity. It was found that thiocyanate ion showed high positive interference. Iodide ion in rainwater was determined by the standard addition method without pre-concentration. The iodide ion content in rainwater was (12) ppb (RSD <10%).
Iodide Spectrophotometry Catalysis Optimization Interferences

"Fundamental Study Of The Determination Of Iron And Cobalt Using 5-dimethylamino-2-nitrosophenol As Color Reagent By Continuous-flow Stream Propelled By Gas Pressure"
Bunseki Kagaku 1983 Volume 32, Issue 3 Pages 191-196

Abstract: The flow streams are propelled by gas pressure in the flow injection system, and 2-nitroso-5-dimethylaminophenol (nitroso-DMAP) is used as the color reagent for iron and cobalt. The signals were detected with a spectrophotometer equipped with a flow cell (18 µL). For the determination of iron(II), the reagent and carrier stream solutions were the nitroso-DMAP solution (pH 9.2) and 10^-3 M sulfuric acid solution respectively, and were flowed at about 1 mL/min, and the signals were detected at 750 nm. The calibration curve was linear from 2 x 10^-7 M to 5 x 10^-4 M of iron. For the detection of cobalt, the reagent stream and carrier stream solutions were the solution of nitroso-DMAP dissolved in trisodium citrate solution and 10^-3 M sulfuric acid solution, respectively. After mixing the reagent stream and carrier stream solutions in the reaction coil, the sulfuric acid solution (4M) was mixed in order to decrease the reagent blank and decompose other metal chelates such as iron, copper and nickel chelates, and the signals were detected at 530 nm. The calibration curve was linear from 5 x 10^-7 M to 6 x 10^-6 M of cobalt. By the proposed FIA system for cobalt, nickel at concentrations of 10^-3 M, iron(III) at concentrations of 10^-4 M, and iron(II) and copper at concentrations of 5 x 10^-5 M did not interfere with the determination of cobalt, and 0.001% to 0.06% of cobalt in commercially available nickel salts were determined.
Iron Cobalt Spectrophotometry Interferences

"Determination Of Water Hardness By Flow Injection Spectrophotometry"
Bunseki Kagaku 1984 Volume 33, Issue 2 Pages 110-112
Yamane, T.;Kamijo, M.

Abstract: The method was based on the exchange reaction between Ca in the sample and the Mg complex of EDTA in a medium of pH 10. By measuring the change in absorbance (at 645 nm) of hydroxynaphthol blue due to its reaction with Mg, the sum of Mg in the sample and Mg liberated in the exchange reaction could be determined. There was a rectilinear relationship between absorbance and water hardness (measured in terms of CaCO3) up to 103 mg l-1. The flow injection system (shown in a schematic diagram) permitted the analysis of 80 samples per hour, with a coefficient of variation of 0.9 to 2.4%. Results for the analysis of river water and tap-water agreed well with those obtained by standard EDTA titration. The method was simple, and a sample volume of only 20 µL was required for a single analysis.
Calcium Magnesium Hardness Spectrophotometry Method comparison Small sample

"Flow Injection Analysis By Using Turbidimetry For Chloride In River Water"
Bunseki Kagaku 1984 Volume 33, Issue 3 Pages 149-153
Zaitsu, T.;Maehara, M.;Toei, K.

Abstract: A sample (500 µL) was injected into a carrier stream of 0.2 M HNO3 (1.2 mL min-1), which was then mixed with reagent solution [500 mL of 10 mM AgNO3, 75 mL of 1.6 M HNO3 and 25 mL of 0.1% solution of poly(vinyl alcohol)] at the same flow rate. After mixing in PTFE tubing (2 m x 1 mm), the turbidity of the mixture was measured at 440 nm, with use of an 18 µL flow cell. Among co-existing ions in river water, 1 mM SiO32- and -CO32- interfered, but these could be removed by passing the sample stream through a column of Amberlite IRC-50 (H+ form). The calibration graph of peak height vs. concentration. of Cl- was rectilinear for 14 ppm. About 15 samples could be run in 1 h. Recovery from river water was 95 to 103%.
Chloride Spectrophotometry Turbidimetry Amberlite Interferences

"Fluorimetric Determination Of Ammonia In River Water By Flow Injection Analysis"
Bunseki Kagaku 1985 Volume 34, Issue 8 Pages 518-521
Mikasa, H.;Motomizu, S.;Toei, K.

Abstract: The sample was injected into the carrier stream (1.2 mL min-1) of water and mixed with the reagent solution containing 10 mM phthalaldehyde and 0.1 M 2-mercaptoethanol, at pH 9.5, in a PTFE reaction coil (3 m x 0.5 mm). The fluorescence was measured at 486 nm (excitation at 350 nm). Interference from amino-acids was removed by using an anion-exchange (Amberlite IRA-400) column in the flow stream between the sample injection valve and the reaction coil. Between 3 and 150 ppb of NH3 could be determined.
Ammonia Ion exchange Fluorescence Amberlite Interferences

"Spectrophotometric Determination Of Boron By Flow Injection Analysis"
Bunseki Kagaku 1986 Volume 35, Issue 4 Pages 344-348
Toei, K.;Motomizu, S.;Oshima, M.;Onoda, M.

Abstract: River water or seawater was analyzed by flow injection by mixing with reagent solution containing H-resorcinol [4-(2,4-dihydroxyphenylazo)-5-hydroxynaphthalene-2,7-disulfonic acid] and EDTA in ammonium acetate buffer solution (pH 5.5); determination was by measuring the absorbance at 510 nm. The calibration graph was rectilinear for 1 ppm of B, and the detection limit was 5 ppb. Interference from ions commonly found in water samples was removed by the addition of EDTA.
Boron Spectrophotometry Interferences

"Determination Of Ultratraces Of Cyanide Ion By Flow Injection Analysis With Surfactant Bilayer Vesicle-catalyzed And Uranine Sensitized Chemiluminescence"
Bunseki Kagaku 1986 Volume 35, Issue 12 Pages 955-960
Ishii, M.;Yamada, M.;Suzuki, S.

Abstract: Cyanide was determined in a flow injection system in which the sample was injected into a flow of 0.05 M NaOH - 7.5 mM didodecyldimethylammonium bromide and a 1 mM solution of uranin (C. I. Acid Yellow 73) was added subsequently. Measurement of the chemiluminescence produced provided a limit of detection of 2 nM for a 20 µL sample injection or 0.3 nM in a continuous sample flow, with a rectilinear range of two orders of magnitude, a coefficient of variation of 2.1% for 0.05 ng of CN- (n = 10) and a sampling rate of up to 360 h-1. The method was applied to determination of CN- in river water.
Cyanide Chemiluminescence Catalysis Surfactant Ultratrace

"Spectrophotometric Determination Of Nitrate Ion Using Nitrosation/flow Injection Analysis"
Bunseki Kagaku 1987 Volume 36, Issue 3 Pages 207-209
Rui, S.C.;Motomizu, S.;Toei, K.

Abstract: Sample solution was injected into a stream of 1 mM EDTA (pH 8) and passed through a reduction column (30 cm x 2 mm) packed with copperized cadmium. The stream was then mixed with 0.8 mM NN-1,1'-phenyliminodipropan-2-ol - 0.35 M HCl - 0.15 M H3PO4 and passed through a reaction coil (2 m x 0.5 mm) at 80°C. The resulting stream was passed through a cooling coil (50 cm x 0.5 mm) before spectrophotometric detection at 500 nm. The calibration graph was rectilinear up to 0.2 mM NO3-. The limit of detection was 1 µM-NO3- and the coefficient of variation (n = 10) was 0.4%. The sampling rate was 40 h-1. Nitrate was determined by this method in river water at 10 µM level.
Nitrate Spectrophotometry Column EDTA Heated reaction Reduction column

"Determination Of Total Carbonate-carbon In River Water By Ion Chromatography With Photometric Detection"
Bunseki Kagaku 1987 Volume 36, Issue 8 Pages 503-507
Hironaka, T.;Oshima, M.;Motomizu, S.

Abstract: Total carbonate-C in river water was determined by ion chromatography on an anion-exchange column (5 cm x 4.6 mm) of TSKgel IC-Anion PW with 0.4 mM trimellitate(I) (pH 7.5) as mobile phase and detection of the decrease in absorbance of I at 270 nm. Interference from Ca(II) and Mg(II) was removed by passing the sample solution through a cation-exchange cartridge (Na+ form). Interference from Cl-, SO42- and NO3- was corrected for by using the summation of peak areas of co-existing anions. Results agreed well with those obtained by flow injection analysis.
Carbonate HPIC Spectrophotometry Interferences Method comparison

"Continuous-flow Determination Of Total Organic Carbon In Water By Membrane Separation/chemiluminescence Detection"
Bunseki Kagaku 1988 Volume 37, Issue 3 Pages 133-136
Aoki, T.;Ito, K.;Munemori, M.

Abstract: The sample solution was mixed with 0.25 M H2SO4 at 5.2 mL min-1 before CO32- was removed from the solution by debubbling. The solution was mixed with alkaline 7% S2O82- solution at 2.6 mL min-1 followed by heating in a reaction coil (8 m x 1.5 mm) maintained at 210°C. The inorganic CO32- produced from the oxidation of organic species by S2O82- was caused to react with 3 M H2SO4 to convert CO32- to CO2 and the CO2 was fed to a double-tube separation unit (inner PTFE tube: 50 cm x 1 mm; outer borosilicate glass tube: 50 cm x 2.5 mm). Permeation of CO2 through the micro-porous PTFE membrane and treatment with luminol reagent (1 mM luminol - 20 mM H2O2 - 0.02 mM CoCl2 - 10 mM borate buffer of pH 9.0), which flowed at 0.22 mL min-1 in the inner tube, was carried out. The chemiluminescence observed was detected by using a photomultiplier tube to give a detection limit of 0.03 ppm of total organic C, a calibration graph rectilinear from 0.06 to 12 ppm and a coefficient of variation (n = 5) of 1.5% for 4.8 ppm of total organic C. Samples of river and seawater were analyzed.
Total organic carbon Chemiluminescence Heated reaction Teflon membrane

"FIA Of Cationic Surfactants Using Plasticized Poly(vinyl Chloride)-membrane Electrode"
Bunseki Kagaku 1991 Volume 40, Issue 1 Pages 1-6
Masadome, T.;Imato, T.;Ishibashi, N.

Abstract: An FIA system was proposed for determining cationic surfactants which incorporates an anion-exchange resin column, aqueous 50% methanol as mobile phase and a plasticized poly(vinyl chloride)-membrane electrode with phthalic acid 2-ethylhexyl ester as detector. The calibration graph was rectilinear from 0.5 to 10 µM-dodecyltrimethylammonium ion and the detection limit was 10 nM. Inorganic electrolytes and anionic and nonionic surfactants did not interfere. The method was applied in the determination of trace cationic surfactants in river water.
Surfactants, cationic Electrode Column Interferences Resin

"Spectrophotometric Determination Of Sodium And Potassium By FIA After Separation On A Cation-exchanger Column And Solvent Extraction"
Bunseki Kagaku 1991 Volume 40, Issue 5 Pages T107-T112
Yoshida, K.;Motomizu, S.

Abstract: Sodium and K ions were separated by passing aqueous sample solution through a cation-exchanger column (1.2 cm x 2.5 mm) with 0.4 mM EDTA.3Li as the eluent stream. The eluate was made alkaline (pH 10) by passing through the anion-exchanger membrane tubing (1 m) kept in 0.1 M LiOH, then mixed with benzene - chlorobenzene (1:1) containing 3 mM tetrabromophenolphthalein ethyl ester and 2 mM dicyclohexano-18-crown-6 and passed through an extraction coil (2 m x 0.5 mm). The absorbance of the organic phase was measured at 615 nm after phase separation with use of a PTFE porous membrane. Calibration graphs were rectilinear up to 0.5 mM Na+ and 80 µM-K+. Sample throughput was 12 h-1. The method was used in the analysis of river and tap water.
Potassium Sodium Spectrophotometry Sample preparation Column EDTA Phase separator Solvent extraction Tubular membrane

"Determination Of Seven Trace Elements In Environmental Water Samples By Inductively Coupled Plasma Mass Spectrometry With Online Preconcentration"
Bunseki Kagaku 1993 Volume 42, Issue 7 Pages 423-428
Akatsuka, K.;McLaren, J.W.;Berman, S.S.

Abstract: An online pre-concentration method was studied to allow the simultaneous determination of Mn, Co, Ni, Cu, Zn, Cd and Pb in 5 mL environmental water samples by inductively coupled plasma mass spectrometry. A semiautomated system with a microprocessor-controlled high performance quaternary gradient pump and valves was used to lead and transport the mobile phase. The system includes a column containing silica-immobilized 8-hydroxyquinoline. The pH of the samples was adjusted to 8 to improve the retention of several elements, in particular manganese. Quantitative elution from the column took 3.5 min with a 1.5 M HCl/0.6 M HNO3 mixture at a flow rate of 2.0 mL min-1. Mn and Co were determined by a standard additions technique, and stable isotope dilution was applied for Ni, Cu, Zn, Cd and Pb. The good precision and accuracy of this method are demonstrated by analyzing standard samples of riverine water (SLRS-2), estuarine water (SLEW-1) and coastal seawater (CASS-2). The detection limits of the method range from 7 ng L-1 for Cd to 130 ng L-1 for Zn. [References: 18]
Manganese Cobalt Nickel Copper Zinc Cadmium Lead Mass spectrometry Preconcentration Computer Column Immobilized reagent Silica 8-Hydroxyquinoline Reference material Standard additions calibration

"Assembly Of A New Gas Diffusion Unit And Its Application To The Determination Of Total Carbonate And Ammoniacal Nitrogen By FIA"
Bunseki Kagaku 1993 Volume 42, Issue 9 Pages T123-T128
Sanada, M.;Oshima, M.;Motomizu, S.

Abstract: A gas diffusion unit was developed (diagrams given) and used in the flow injection spectrophotometric determination of ammonia-N or carbonate in natual waters. The unit consisted of an inner microporous PTFE tube (pore size 0.2 µm) and an outer PTFE tube. Sample was injected into a carrier stream, where the analyte was converted into a gaseous species and passed through the inner PTFE tube into the reagent stream, which flowed between the outer and inner tubes. The change in pH caused the color of the reagent stream to alter, which was detected spectrophotometrically. For the ammonia-N determination, the carrier stream was 0.02 M NaOH, the reagent stream contained 0.125 mM Cresol Red of pH 7 (details given) and the absorbance was monitored at 550 nm. For the determination of carbonate, the carrier stream was 1.8 mM H2SO4, the reagent stream contained 0.125 mM Cresol Red of pH 9 (details given) and absorbance was measured at 410 nm. The detection limits for ammonia-N and carbonate, respectively, were 0.03 and 0.96 mg/l; the corresponding calibration graphs were linear up to 3.5 and 172 mg/l. Sampling rates were 30 and 20 per h, respectively. The method was applied to river and seawater.
Carbonate Ammonia, nitrogen Spectrophotometry Gas diffusion

"The Metal-complexing Capacity Of Natural Waters Measured On The Basis Of Solvent Extraction And Reverse FIA"
Bunseki Kagaku 1995 Volume 44, Issue 12 Pages 989-999
Itabashi, H.

Abstract: Methods based on the backextraction, with the sample, of Cu(II) from its bis(benzoyltrifluoriacetonato)-complex in an organic solvent and on reverse FIA (manifold illustrated) are described. Results obtained by the two techniques were of the same order of magnitude. Methods for the measurement of copper(II) complexing capacity (CuCC) of natural waters by using a back-extraction of bis(benzoyltrifluoroacetonate) copper(II) (Cu(bfa)(2)) and the dithizone extraction rate of copper(II) complex were described. From the measurements of CuCC of river water samples, it was found that the CuCC of the water sample in the urban area was larger than that up-stream, due to a ligand originating from human activities. The conditional stability constant (beta) of the resulting copper(II) complex was determined by using the back-extraction method.beta values of river water samples were 10(9) similar to 10(10) order of magnitude. Free copper(II) concentration of the Kiryu river was estimated by using the side-reaction coefficient in the extraction of copper(II) with tenoyltrifluoroacetone. The free copper(II) concentration was estimated to be 10^-13 mol L-1 which is 10^-5 of total copper. Most of the copper(II) in the river, therefore, is complexed with naturally occurring ligands. A procedure for the measurement of metal complexing capacity by using reverse flow injection analysis (r-FIA) system was also described. The applicability of the method was evaluated by measuring zinc(II), cadmium(II) and lead(II) complexing capacities of both river and lake waters. The values obtained by the r-FIA system were in the same order of magnitude as those obtained by the back-extraction method, indicating the usefulness of the r-FIA method for the estimation of complexing capacity. (35 References)
Complexing capacity Spectrophotometry Sample preparation Indirect Redox Reverse Solvent extraction Stability constants Titrations Dithizone

"Determination Of Antimony In River Water By Hydride-generation Atomic Absorption Spectrophotometry"
Bunseki Kagaku 1996 Volume 45, Issue 11 Pages 1041-1044
Narasaki, H.;Hayashi, K.;Hoshina, A.

Abstract: A diagram of the continuous-flow hydride-generation system is presented. The sample was made 0.7 M in H2SO4 and mixed at 5 ml/min with a stream (3 ml/min) of 2% NaBH4 solution, and after 30 s the SbH3 generated was swept in a stream (2 l/min) of N2 to a quartz atomizer at 900°C for absorbance measurement at 217.6 nm. The detection limit was 0.6 ng/ml of As(III). Transition metals were masked with Chelex-100, and As(V) was reduced with KI. The result for a NIST biological standard reference material agreed with the certified value. The method was applied to river water.
Antimony Spectrophotometry Reference material Chelex

"Simultaneous Determination Of Nitrate And Nitrite Ion By Micro-flow Injection Analysis"
Bunseki Kagaku 1998 Volume 47, Issue 6 Pages 375-380
Lan Ma, Mitsuko Oshima, Shoji Motomizu and Takayasu Hattori

Abstract: To minimize the ample size, reagent consumption and waste, a micro-flow injection analysis (µFIA) was investigated and applied to the simultaneous determination of NO3- and NO2- in water samples. The NO3- was reduced to NO2- with reduction efficiency 99% on line by passing through a mini column (0.53 mm i.d. x 5 cm) packed with 60-80-mesh powd. Cd/Cu, and was detected at 538 nm. The carrier solution contained EDTA and NaCl (pH 8.1-8.4) and the reagent solution contained sulfanilamide, N-(1-naphthyl)ethylenediamine, and HCl. The carrier stream was split into 2 streams, and one of them passed through the mini column to give a peak derived from NO3- and NO2-, and the other stream passed through a bypass column packed with glass beads to give a peak derived from NO2-. The detection limit of NO3- and NO2- were ~1 x 10^-7 M.
Nitrate Nitrite Spectrophotometry Microfluidic Reduction column Reagent consumption Simultaneous analysis Sample splitting

"Analysis Of River Water By ICP-MS With Online Preconcentration Using Flow Injection"
Can. J. Anal. Sci. Spectrosc. 1998 Volume 43, Issue 2 Pages 43-48
Beauchemin, D.;Specht, A.A.

Abstract: A flow injection manifold is described for online pre-concentration. of several elements and their determination by inductively coupled plasma mass spectrometry. This manifold incorporates a cleaning column on the buffer line to remove trace contaminants from the buffer prior to its mixing with the sample. A 2 M HNO3 eluent is used to determine elements which suffer from spectroscopic interferences from Cl-containing compounds The pre-concentration. factor can easily be changed by simply modifying the sample loading time (i.e., the amt. of time the sample is pumped through the anal. column). A 30-fold pre-concentration. (using 1.5 mL sample and 50 µL eluent) was used to analyze certified river water, SLRS-2. Under these conditions, sample throughput was ~20 samples/h. Results agreed well with certified values for V, Co, Cd, and Pb using standard additions, and for V, Co, Cd, and Sb using external calibration. Both calibration strategies provided results of similar accuracy and precision, but the latter was far less time-consuming. Trace determination of ubiquitous elements such as Zn is still precluded by a high blank.
Vanadium Cobalt Cadmium Lead Mass spectrometry Reference material Preconcentration Interferences

"Determination Of Trace Heavy Metals By Flow Injection Analysis With Adsorptive Stripping Voltammetric Detection"
Chem. Anal. 1995 Volume 40, Issue 1 Pages 1-12
Strozik, M.;Kubiak, W.W.;Kowalski, Z.

Abstract: Sample solutions based on NH3/NH4Cl buffer (200 µL; containing Pb and Cd) were treated with 80 µM-oxine and injected into a 0.01 M NH3/NH4Cl buffer carrier solution of pH 9.5. After a delay time for the sample to reach the cell, pre-concentration was started at -300 mV. The delay and pre-concentration times are dependent on the flow rate and the sample volume, e.g., for a 200 µL sample with a flow rate of 0.71 ml/min, the delay was 5 s and the accumulation time was 20 s. After accumulation, the negative differential pulse potential scan was started; with a scan rate of 40 mV/s and a pulse amplitude of 50 mV. Measurements were made with a fresh Hg drop and without stopping the flow. The detector was homemade based on a PAR model 310 polarographic detector and used with a hanging-Hg-drop detector; a SCE and Pt auxiliary electrodes were immersed with the detector in the supporting electrolyte. Calibration graphs were linear from 2.50 nM-Cd and 20-250 nM-Pb with detection limits of 1 nM-Cd and 4.9 nM-Pb. Interferences are discussed and the method was applied to river water.
Cadmium Lead Voltammetry Interferences Apparatus 8-Hydroxyquinoline

"Screening Of Water Samples For Polar Organic Micropollutants Using On-column Sample Enrichment"
Chromatographia 1995 Volume 40, Issue 11-12 Pages 631-637
Hupe, K.P.;Riedmann, M.;Rozing, G.

Abstract: The use of a single column for extraction-enrichment and separation was investigated. The system is shown diagrammatically. The sample is loaded directly on to the LC column where enrichment and separation occur sequentially. The LC pump with the integrating proportioning value provides the gradient, loads the sample, purges, washed and activates the column, thus resulting in a flow injection type system whilst still retaining some chromatographic properties. The system was applied to the determination of polar pesticides and aromatic sulfonates in water. The water (tap and river) was filtered before injection. Separations were performed on 5 µm BDS-C 18 or Hypersil ODS columns. The mobile phases comprised acetonitrile (solvent A) and water (solvent B) for pesticides; and H2O/6 mM Na2HPO4/ 5 mM tetrabutylammonium sulfonate of pH 6.5 (solvent A) and 75% methanol/ 6 mM Na2HPO4/5 mM tetrabutylammonium sulfonate (solvent B) for aromatic sulfonates (other conditions tabulated). Results were compared with those obtained from conventional methods.
Aromatic, sulfonates HPLC Apparatus

"Continuous-flow Method For Simultaneous Determination Of Nitrate And Ammonia In Water"
Environ. Sci. Technol. 1986 Volume 20, Issue 5 Pages 515-517
Toyoaki Aoki, Satoshi Uemura, and Makoto Munemori

Abstract: River water was analyzed by continuous-flow analysis. The sample was mixed with 0.3% sulfanilic acid solution, 7 M NaOH and TiCl3 solution, and the NH3 present in the sample or produced by the reduction of NO3- permeated through a micro-porous PTFE membrane into a buffer solution containing phthalaldehyde - 2-mercaptoethanol. The fluorescence of the buffer solution was then measured at 486 nm (excitation at 370 nm); the original NH3 content was determined as above but without the reduction of the NO3-. The calibration graphs for NO3- and NH3 were rectilinear for 0.5 µM to 0.2 mM and 0.2 µM to 0.2 mM, respectively, and the corresponding detection limits were 0.18 µM and 0.018 µM. The coefficient of variation were 3.3 and 4.4% for NO3- and NH3, respectively. Interference due to methylamine and ethylamine was reduced by lowering the pH of the reaction solution
Ammonia Nitrate Fluorescence Gas diffusion Interferences Microporous membrane Teflon membrane

"Chemiluminescence Reaction In Chromium(VI) - Ferrocyanide - Luminol System"
Fenxi Huaxue 1992 Volume 20, Issue 1 Pages 61-63
Lu, J.R.;Zhang, X.R.;Zhang, Z.J.

Abstract: Tapwater, river water or industrially-polluted water is applied at 5 mL min-1 to a column (20 x 2 cm) of 732 strongly-acidic cation-exchange resin. Some of the eluate is mixed with 0.5 mL of 0.1% K4Fe(CN)6, 0.5 mL of 0.1 M HCl, 0.5 mL of 1% KAl(SO4)2, 0.5 mL of 10 mM EDTA and water to 50 mL and the solution is injected into a flow injection chemiluminescence analyzer. for reaction with 2.5 mM luminol in 0.4 M NaOH followed by chemiluminescence detection. The calibration graph was rectilinear from 0.1 ng mL-1 to 6 µg mL-1 of Cr; the detection limit was 20 pg mL-1. The coefficient of variation was 2%. Only VV interfered. Results are compared with those obtained by diphenyl carbazide method.
Chromium(VI) Ion exchange Chemiluminescence Interferences Method comparison

"Chemiluminescence Reaction Of Lucigenin And Inorganic Reductants. 2. Chemiluminescence Reaction Of Molybdenum(III) Lucigenin"
Fenxi Huaxue 1994 Volume 22, Issue 9 Pages 909-912
Lu, J.R.;Zhu, Z.J.

Abstract: A sample (pH adjusted to 3.5) was passed through a Jones reactor in a flow injection system before mixing with streams of 0.5 mM lucigenin and 0.4 M NaOH (all at 3 ml/min) and measuring the chemiluminescence. Calibration graphs were rectilinear from 0.1 ng/ml to 1 µg/ml Mo; the detection limit was 20 pg/ml. No interference was observed. The method was used to analyze tapwater and river water, with recoveries of 96-97% and RSD of 1.4-5.2%.
Molybdenum(III) Chemiluminescence Interferences Jones reductor

"Application Of A Photochemical Reaction In A Flow Injection System. 5. Determination Of Trace Amounts Of Nitrite With A Nitrate/luminol Photochemical Reaction System"
Fenxi Huaxue 1995 Volume 23, Issue 3 Pages 321-324
Liu, D.J.;Liu, R.M.;Sun, A.L.;Liu, G.H.

Abstract: Sample was adjusted to pH 5 and injected into a carrier stream of H2SO4 (1.5 ml/min) to mix in a photochemical reactor (180 cm) while irradiated with a high-pressure Hg lamp. It was then carried via a connection tube (11 cm) to react with a stream of 50 µM-luminol containing 0.1 M KOH of pH 13 (0.5 ml/min) in a reactor (3 cm) and the chemiluminescence intensity was measured. The calibration graph was linear for 50 nM- to 0.1 mM nitrate and the RSD were 0.74-0.92%. Fe(III), Cu(II), Co(II) and Ni(II) interfered seriously. The method was applied to river and well water and the results were compared with those obtained by the phenol disulfonic acid method.
Nitrate Chemiluminescence Photochemistry Interferences Method comparison

"Determination Of Trace Lead In Water By Flame Atomic Absorption Spectrometry Coupled With Flow Injection Online Preconcentration"
Fenxi Huaxue 1996 Volume 24, Issue 8 Pages 957-960
Jin, J.C.;Chen, H.W.;Shen, X.Y.

Abstract: Portions of standard Pb solution were mixed with 2.5 mL aqueous ascorbic acid, 5 mL 1% 1,10-phenanthroline in 2 M HCl, 5 mL 10% thiourea and the mixture was diluted to 50 mL with water. Portions of the solution were injected at 5.6 ml/min into a flow injection manifold (schematic shown) and mixed with a reagent stream of 0.25% sodium diethyldithiocarbamate in 0.02 M acetate/0.04 M ammonia water at pH 9.36, at 0.8 ml/min in a knotted reactor (150 cm long). The chelate formed was adsorbed on its PTFE tubing to effect pre-concentration for 40 s. The valves were switched to allow the IBMK eluent to be carried by a stream of water at 3.5 ml/min to the knotted reactor The eluate was transferred at 3.5 ml.min to the flame atomic absorption spectrometer for detection of atomized Pb species at 283.3 nm. The calibration graph was linear up to 300 µg/l with a detection limit of 2.9 µg/l. RSD were 1.4 and 1%, respectively, for 40 and 200 µg/l of Pb. Interference levels for ten foreign ions on the determination of 200 µg/l of Pb are listed. With 40 s pre-concentration, an enhancement factor of 32 was achievable. The method was applied to the analysis of tap water, river water, industrial waste water and seawater, with recoveries of 96-103%.
Lead Spectrophotometry Preconcentration Interferences MIBK Complexation Knotted reactor

"Determination Of Trace Arsenic In Water By Luminol/hydrogen Peroxide/chromium(III) Chemiluminescence After Sulfhydryl Cotton Enrichment And Separation"
Fenxi Huaxue 1996 Volume 24, Issue 11 Pages 1320-1322
Jia, S.H.;Lu, J.Y.;Zhang, H.Q.

Abstract: Water (100 ml) was adjusted to 1 M HCl, treated with 2 mL reducing reagent containing 200 g/l KI and 20 g/l thiourea, heated at 80°C for As was eluted with hot concentrated HCl. The eluate was heated with 5 mL 50 mM K2Cr2O7 and 1 mL 1 M H2SO4 for 10 min then 1 mL 0.1 M EDTA was added, the pH was adjusted to 2.5, and the solution was diluted with water. A portion was injected into a FIA system to react with streams of 0.25 µM-luminol and 40 mM H2O2 and the generated chemiluminescence was measured. The calibration graph was linear from 0.1 µg/l to 0.1 mg/l As(III) and the detection limit was 34 ng/l. There was no interference. The method was used in the direct analysis of tap water and river water, with recoveries of 95-103% and RSD of 4.2-10.6%.
Arsenic Chemiluminescence Sulfhydryl cotton Interferences Heated reaction Preconcentration

"Automatic Hyphenated Technique Of Flow Injection Online Preconcentration With Microcolumn - Electrothermal AAS"
Fenxi Kexue Xuebao 1997 Volume 13, Issue 1 Pages 35-38
Sun Xiaojuan, B.Welz, M.Sperling

Abstract: The cited setup consisted of a pre-column and a microcolumn along with an ET atomizer, equipped with a L'vov platform, and an atomic absorption spectrometer with a PE 4100 for Zeeman effect background correction. After optimization for the analysis of river or seawater, a 9 µL C18 bonded silica-gel solid sorbent microcolumn was used for pre-concentration of the Pb-diethyldithiocarbamate complex. Elution (0.25 ml/min) was with 80 µL methanol after percolation with 0.02% HNO3 for 10 s. The total eluate was transferred at a flow rate of 0.08 ml/min into the graphite atomizer AAS. The detection limit was 4.5 ng/l Pb. An enrichment factor of 64 could be achieved. Recovery was 98%. Results for the standard reference materials agreed closely with the certified values.
Lead Spectrophotometry Preconcentration Diethyldithiocarbamate Complexation Reference material Column Optimization

"Determination Of Nitrite In Water By Catalytic-kinetic Flow Injection Fluorimetry"
Fenxi Shiyanshi 1997 Volume 16, Issue 1 Pages 26-28
Wang, K.T.;Chen, X.G.;Hu, Z.

Abstract: Sample (120 µL) was injected into a carrier stream of water (0.8 ml/min) that merged first with a stream of 2.5 mM rhodamine 6G in 0.5 M H2SO4 (0.8 ml/min) in a mixing coil (12 cm x 0.5 mm i.d.) and then with a stream of 1.2 mM KBrO3 (1.2 ml/min) in a reactor (100 cm x 0.5 mm i.d.) before fluorimetric detection at 549 nm (excitation at 519 nm). The calibration graph was linear for 9-100 µg/l of nitrite, with a detection limit of 3.5 µg/l. Large quantities of chloride were removed by precipitation with Ag(I). The method was applied to the analysis of river water, well water and waste water, with recoveries of 94-108% and RSD of 0.81-1%. The sampling frequency was 65 runs per h.
Nitrite Fluorescence Catalysis Interferences Precipitation Kinetic

"Interactions Of Manganese With The Nitrogen-cycle Alternative Pathways To Dinitrogen"
Geochim. Cosmochim. Acta 1997 Volume 61, Issue 19 Pages 4043-4052
George W. Luther, III, Bj&oslash;rn Sundby, Brent L. Lewis, Paul J. Brendel and Norman Silverberg

Abstract: The conversion of combined nitrogen (ammonia, nitrate, organic nitrogen) to dinitrogen (N-2) in marine sediments, an important link in the global nitrogen cycle, is traditionally assumed to take place only via the coupled bacterial nitrification-denitrification process. We provide field and laboratory evidence that N-2 can also be produced by the oxidation of NH3 and organic-N with MnO2 in air. The reduced manganese formed in this reaction readily reacts with O-2, generating reactive Mn(III, TV) species to continue the oxidation of NH3 and organic-N to N-2. Free energy calculations indicate that these two reactions are more favorable as a couple than the oxidation of organic matter by O-2 alone. We also provide field evidence consistent with the reduction of NO3- to N-2 by dissolved Mn2+. These two reactions involving nitrogen and manganese species can take place in the presence and absence of O-2, respectively. Our field evidence suggests that the oxidation of NH3 and organic-N to N-2 by MnO2 in the presence of O-2 can outcompete the oxidation of NH3 to NO3- in Mn-rich continental margin sediments and thereby short-circuit the nitrification/denitrification process. The MnO2 catalyzed reaction may account for up to 90% of the N-2 formation in continental margin sediments, the most important N-2 producing environments in the marine N cycle. The oxidation of NH3 and organic-N by MnO2 in the presence of O-2 can explain why N-2 can form in oxic sediments; it can also explain why denitrification rates measured by acetylene inhibition and labeled tracers can give lower estimates than direct measurements of N-2 production. Copyright (C) 1997 Elsevier Science Ltd. 43 References
Nitrogen Catalysis

"Oxidation Kinetics Of Manganese(II) In Seawater At Nanomolar Concentrations"
Geochim. Cosmochim. Acta 1997 Volume 61, Issue 23 Pages 4945-4954
Peter J. von Langen, Kenneth S. Johnson, Kenneth H. Coale and Virginia A. Elrod

Abstract: Manganese oxidation rates were determined at low (~ 20 nM) concentrations in seawater by measuring dissolved manganese (Mn(II)) using flow injection analysis with chemiluminescence detection. Mn(II) was measured in samples that had been filtered (0.2 µm) and kept in the dark under controlled temperature and pH conditions for time periods up to 6 months. Eight 9 L carboys with mean pH values ranging from 8 to 8.7 were held at 25°C, another carboy (pH = 9.32) was kept at 5°C. Oxidation followed the Morgan (1967) homogeneous rate equation (d[Mn(II)]/dt = k1 [O2][OH-]2[Mn(II)]). The mean rate constant k1 = 1.7 ± 0.7 x 10^12 M-3 d-1 (95% CI), determined using hydroxide ion activities determined with pH measurements on the NBS scale, was in agreement with work by Morgan (1967; k1 = 4 x 10^12 M-3 d-1) and Davies and Morgan (1989; k1 = 1.1 x 10^12 M-3 d-1) in dilute solutions. The rate constant at 5°C was 1.3 ± 0.3 x 10^12 M-3 d-1. If free hydroxide concentrations (based on the free proton pH scale) are used, then the rate constant at 25°C was k1* = 0.34 ± 0.14 x 10^12 M-3d-1.

Autocatalytic increases in Mn(II) oxidation rates, as predicted by a heterogeneous reaction mechanism (Morgan, 1967) (d[Mn(II)]/dt= k2'[Mn(II)][MnO2]) were not observed, indicating that the homogeneous reaction dominates Mn(II) oxidation at low nM concentrations in seawater. Bacteria were enumerated by 4',6-diamidino-2-phenylindole (DAPI) staining during the experiments. No significant correlation between bacterial concentrations and Mn(II) oxidation rates was found.

Manganese(II) Kinetic

"Determination Of Chromium(VI) In Huai River Water By Flow Injection Chemiluminescence Method"
Huanjing Wuran Yu Fangzhi 1998 Volume 20, Issue 6 Pages 34-35
Han Heyou, He Zhike, Luo Qingyao, Yu Ximao

Abstract: A reversed flow injection chemiluminescence method based on quercetin-H2O2-Cr(VI)-KOH chemiluminescence system for determination of Cr(VI) in Huai River water is proposed. The detection limit was 2.0 x 10^-9 g/mL, linear range 1.0 x 10^-8-2.0 x 10^-6 g/mL, and relative standard deviation 1.6%.
Chromium(VI) Chemiluminescence Reverse

"Continuous-flow Determination Of Organophosphorus Pesticides Using Solid-phase Extraction Coupled Online With High Performance Liquid Chromatography"
Int. J. Environ. Anal. Chem. 1992 Volume 46, Issue 4 Pages 245-253
Farran, A.;De Pablo, J.;Hernandez, S.

Abstract: A column (5 cm x 3 mm) of Amberlite XAD-2 resin was used for trace enrichment of diazinon (I), azinphos-methyl (II) and fenthion (III) in a low-pressure continuous-flow system (described) with methanol as mobile phase (1.6 mL min-1). HPLC was carried out on an RP-18 column (22 cm x 4 mm) with aqueous 80% methanol as mobile phase (1 mL min-1) and detection at 220 nm. Optimization of conditions is discussed, including pre-concentration. time, flow rate and pH. Calibration graphs (peak heights) were rectilinear in the range 0.07 to 2 mg L-1 for all three pesticides; the limits of detection were 90 µg L-1 for I and III and 40 µg L-1 for II. Recoveries were >95%. Interference from other pesticides and related compounds could be eliminated by using aqueous 70% methanol as the HPLC mobile phase. The method was successfully used for the determination of I, II and III in river water samples. A XAD-2 resin is used for trace enrichment of 3 organophosphorus pesticides (diazinon, azinphosmethyl, and fenthion) on an unsegmented-flow solid-phase pre-concentration. system, coupled online with a HPLC with UV detection at 220 nm. The influence of different parameters (e.g. pesticides water concentrations., water pH, pre-column characteristics, pre-concentration. and elution times and solvent flow rates) on the retention and recovery of the pesticides was studied. Recoveries >95%, were obtained for the pesticides, except for diazinon at sample volumes >500 mL. Calibration graphs are linear in the range of 0.07-2 mg/L for each pesticide under standard conditions, although concentrations. down to 5 µg/L can be measured. The method was been successfully applied to spiked river water samples.
Pesticides, organophosphorus HPLC Sample preparation Solid phase extraction Amberlite Resin Interferences Optimization

"Determination Of Nitrate In The Presence Of Nitrite In Natural Waters By Flow Injection Analysis With A Non-quantitative Online Cadmium Reductor"
Int. J. Environ. Anal. Chem. 1994 Volume 57, Issue 4 Pages 263-277
S. -C. Pai; J. P. Riley

Abstract: Several analytical problems in the determination of nitrate using flow injection analysis (FIA) coupled with an on-line Cd reductor have been studied. It was found difficult to prepare a nearly 100%-efficient copperized Cd reductor which maintains its efficiency over a lengthy period. Instead, the use of a narrow and lower efficiency Cd coil is recommended because it is more stable and therefore more suitable for FIA. Since the conversion of nitrate to nitrite is not quantitative, results for nitrate tend to be over-estimates when nitrite is also present. This problem has been solved by using a simple correction scheme to compensate for the effect of nitrite, thus enabling the correct nitrate concentration to be evaluated. The validity of the correction procedure has been confirmed by running a series of known standards containing both nitrate and nitrite with three types of FIA manifolds. Results for nitrate were accurate for fresh and saline waters even when the co-existing nitrite concentrations were high.
Nitrate Spectrophotometry Interferences Reduction column Manifold comparison

"New Approach For Determining Low Level Nutrients In Saline, Brackish And Fresh Water Samples"
Int. Labmate 1993 Volume 18, Issue 1 Pages 7-9
Ranger, C.;Diamond, D.

Abstract: A description is given of the hardware, software and chemistry involved in the QuikChem AE system (Lachat Instruments, Milwaukee, WI, USA) developed for determining low level nutrients in water samples of 0 to 35 ppt salinity. The system consists of a multi-channel continuous-flow analyzer. which uses the FIA technique and a color reaction which is detected photometrically. The system gives negligible interference from refractive index and salt effects and the use of ultra pure water for standards, carrier and blanks mean there is no need to obtain nutrient depleted seawater for preparing standards. The ranges or detection limits were 0.049 µM-NH3, 0.017 µM-nitrate, 0.025 µM-phosphate and 0.048 µM-silicate.
Nitrate Phosphate Silicate Spectrophotometry Multichannel Lachat Refractive index Interferences

"Determination Of Oxamyl And Methomyl By High Performance Liquid Chromatography Using A Single-stage Post-column Derivatization Reaction And Fluorescence Detection"
J. Agric. Food Chem. 1992 Volume 40, Issue 6 Pages 1026-1029
Steven C. Stafford and Willy Lin

Abstract: Dried, powdered apple, orange, soybean leaf and insect samples (0.5 g), fortified with oxamyl (I) and methomyl (II) were ground with pre-washed C18. The mixtures were packed into a column and, after washing with hexane, I and II were eluted with CH2Cl2, the eluates were evaporated to dryness, and the residues were reconstituted with water (pH 3) and sonicated. The solution, and also river water samples (1 ml), were filtered, then analyzed on a column (25 cm x 4.6 mm) of Zorbax ODS at 40°C with linear gradient elution at 1 mL min-1 with water (pH 3.0) - acetonitrile, programmed from (4:1) to (1:4) during 16 min. Single-stage post-column hydrolysis of the analytes, and derivatization of the methylamine produced, was performed in an online flow reactor at 140°C, with a mixture of o-phthalaldehyde in methanol, aqueous 0.01 M KOH and 2-mercaptoethanol as reagent. Fluorimetric detection was carried out at 455 nm (excitation at 340 nm). A schematic diagram of the post-column reactor is given. The recoveries of both I and II ranged from 72 to 129%, and detection limits were 20 ng g-1 (raw agricultural commodities) and 5 mg mL-1 (water).
Oxamyl Methomyl Fluorescence HPLC Post-column derivatization Heated reaction

"Capillary Enzyme Immunoassay With Electrochemical Detection For The Determination Of Atrazine In Water"
J. Agric. Food Chem. 1995 Volume 43, Issue 4 Pages 1098-1104
Tongbo Jiang, H. Brian Halsall, William R. Heineman, Thomas Giersch, and Bertold Hock

Abstract: A capillary enzyme immunoassay with electrochemical detection has been developed for the determination of atrazine in water. The assay is based on competitive binding between atrazine and alkaline phosphatase-labeled atrazine for a limited number of antibody binding sites. The antibody is attached covalently to a modified capillary surface. The enzymatic product (p-aminophenol) is detected by amperometric flow injection analysis. The calibration curve for atrazine has a linear range of 0.10-10.0µg/L and a detection limit of 0.10µg/L. An assay including six standards can be done in less than 60 min. Intra- and inter-assay precisions at 0.1 and 5.0µg/L are 9 and 8% and 6 and 10%, respectively. Recoveries of added atrazine from commercial bottled water, tap water, and Ohio River water at 0.50 and 5.0µg/L range from 100 to 115%. Simple filtration is the only step needed for sample cleanup.
Atrazine Immunoassay Amperometry

"Flow Injection System With Multisite Detection For Spectrophotometric Determination Of Calcium And Magnesium In Soil Extracts And Natural Waters"
J. Agric. Food Chem. 1996 Volume 44, Issue 1 Pages 165-169
Ana Rita A. Nogueira, Sandra M. B. Brienza, Elias A. G. Zagatto, Jos&eacute; L. F. C. Lima, and Alberto N. Ara&uacute;jo

Abstract: A flow system with a relocatable detector for spectrophotometric determination of calcium (Ca) and magnesium (Mg) in KCl soil extracts and natural waters is presented. O-Cresolphthalein complexon (CPC) was selected as the chromogenic reagent, ammonium-ammonia as the buffer system, and EGTA or 8-hydroxyquinoline as the masking agents for Ca or Mg, respectively. Linearity of the calibration equations was observed for Ca and Mg concentrations up to 80.0 and 15.0 mg/L, respectively. Slight variations in the coefficients of the calibration equations (usually <3%) were found after 4-h working periods. Recoveries between 97.5 and 104.1% were calculated after adding 10.0 mL of Ca at 15.00 mg/L or Mg at 5.00 mg/L Mg to 50.0 mL sample solutions. Precise results (relative standard deviation, <0.02) in agreement with flame atomic absorption spectrometry were obtained. With multisite detection, washing time was not a relevant factor in sampling rate, and an improved sample throughput of 160/h (corresponding to 0.8 mg of CPC per sample) was obtained.
Calcium Magnesium Spectrophotometry 8-Hydroxyquinoline

"Speciation And Determination Of Dissolved Iodide And Iodine In Environmental Aqueous Samples By Inductively Coupled Plasma Atomic-emission Spectrometry"
J. AOAC Int. 1996 Volume 79, Issue 3 Pages 751-756
Kim A. Anderson, Barbara Casey, Elmer Diaz, Peter Markowski, and Brent Wright

Abstract: Samples (5-10 ml) were filtered and diluted tenfold if the salt concentration was >1%. Iodide was determined after filtration by oxidation to I2 in situ with 5 M H2SO4/0.1 M NaNO2 in a simplified continuous-flow manifold (diagram given); a standard nebulizer separated I2 which was measured at 206.16 nm by ICP-AES with use of a Model Perkin-Elmer P-40 ICP-AES instrument with an AS-90 autosampler. I2 was determined without the use of the oxidation reagents. Samples containing both iodide and I2 were analyzed with the oxidizing reagent for the total iodine, without the oxidizing reagents for I2 and iodide was calculated by the difference of the two measurements. The method was applied to seawater, brine and fresh water. Recoveries were 86.5-118.6% with an average of 98.2%. The stability of I2 in environmental samples was briefly investigated.
Iodine Sample preparation Spectrophotometry Speciation

"Microcomputers In A Water Authority Laboratory"
J. Autom. Methods Manag. Chem. 1985 Volume 7, Issue 4 Pages 192-196

Abstract: The microcomputer-based system (designated LABDAPS) described is currently in use in five laboratories that are engaged in monitoring the quality of river water, drinking water and sewage and trade effluents. The system can process data from, e.g., measurement of BOD and suspended solids and from AAS and continuous-flow analyzes; the individual microcomputers are linked to a central computer.

"Novel Approach To Non-segmented Flow Analysis. 4. Aluminum In River Waters"
J. Autom. Methods Manag. Chem. 1991 Volume 13, Issue 4 Pages 147-151

Abstract: Aluminum was determined in natural water with use of a flow analyzer. as described by Malcolme-Lawes and Pasquini (ibid., 1988, 10, 192) and a combined reagent system of Chrome azurol S (C. I. Mordant Blue 29) - hexadecylpyridinium chloride - ethanol at pH 5.0. The detection limit was 18 ppb of Al(III); the coefficient of variation was 1.8%. The effect of interfering ions was discussed.
Aluminum Interferences pH PPB

"A Fully Automated Flow Injection Atomic Absorption System For The Determination Of Copper Traces In Waters With Online Preconcentration In An Ion-exchange Column"
J. Autom. Methods Manag. Chem. 1995 Volume 17, Issue 1 Pages 25-29

Abstract: In the cited system (manifold illustrated) sample was pumped at 8 ml/min through a cation-exchange column of Dowex 50 W-X8 resin (100-200 mesh; 25 mg) for Cu pre-concentration. The eluent (5 M HCl) was then passed through the column (4 ml/min) and the eluted Cu was carried in water (7 ml/min) to the AAS instrument for determination at 324.6 nm using an air-acetylene flame. A time-based injector comprising a timer controlling a solenoid valve was used to operate the system (details given). The analytical characteristics depended on the sample volume. For an 8 mL water sample, the calibration graph was linear for 2-65 ng/ml of Cu and the detection limit was 1.5 ng/ml; a 25-fold enrichment was achieved. The RSD (n = 14) for 4.2-18.8 ng/ml of Cu were 0.6-2.5%. The results for two standard reference river and tap water samples agreed well with the certified valves and the recoveries of Cu were 95-102%. The results also agreed well with those obtained independently by electrothermal AAS.
Copper Ion exchange Spectrophotometry Automation Column Method comparison Preconcentration Reference material

"Sequential Determination Of Silicate And Phosphate In Waters By Flow Injection Spectrophotometry"
J. Flow Injection Anal. 1989 Volume 6, Issue 1 Pages 19-29
A. O. Jacintho, E. A . M. Kronka, E. A. G. Zagatto, M. A. Z. Arruda and J. R. Ferreira

Abstract: A filtered river water sample, preserved with 1.8 M H2SO4, is aspirated at 4 mL min-1 into a flow injection system with intermittent streams in which a carrier stream of 18 mM H2SO4 (4.9 mL min-1) transports the sample to effect reaction of phosphate with 3% of (NH4)2MoO4 in presence of 2 M H2SO4 (to suppress silicate reaction) before reaction with 0.1% of SnCl2 and absorbance measurement at 735 nm. Then the commutator is switched so that the sample enters into a different sampling loop and flows to react with (NH4)2MoO4 and 10% oxalic acid (as inhibitor of phosphate reaction) for spectrophotometric determination of silicate as a yellow heteropoly acid. Sixty samples can be analyzed per hour. For determination of 2.5 to 15 mg L-1 of silicate and 0.25 to 1.5 mg L-1 of phosphate, coefficient of variation are 1%. Detection limit of phosphate is 0.02 µg l-1. Effects of sample volume, flow rate, coil length, pH, order of reagent addition and reagent concentration. are discussed.
Phosphate Silicate Spectrophotometry Commutation Optimization Dual detection

"Determination Of Nitrite And Nitrate By Flow Injection Analysis"
J. Flow Injection Anal. 1989 Volume 6, Issue 2 Pages 137-144
K.Aikawa and R.Motohashi

Abstract: For the determination of NO2- in river water, sample (100 µL) was injected into a carrier stream (1 mL min-1) of water and reacted with 4-aminobenzenesulfonamide in dilute HCl (I) and aqueous N-(1-naphthyl)ethylendiamine dihydrochloride (II); both at 1 mL min-1, and after 2 min, absorbance was measured at 540 nm. For the determination of NO3-, the same system was used (diagram given) but the sample was passed through a Cd - Cu reductant column in a carrier stream of 0.1 M NH4Cl before mixing with I and II and detection at 540 nm. Beer's law was obeyed from 0.01 (detection limit) to 2 and 0.05 (detection limit) to 5 mg L-1 of NO2- and NO3-, respectively. Coefficients of variation (n = 10) were 1%. Results obtained correlated well with those of the Japanese Industrial Standards methods.
Nitrate Nitrite Spectrophotometry Injection technique Method comparison Standard method Reduction column

"Flow Injection Analysis Of Sodium And Potassium By Separation On A Silica-gel Column And Extraction-spectrophotometry. Simplification Of Flow Systems And Enhancement Of Sensitivity"
J. Flow Injection Anal. 1990 Volume 7, Issue 2 Pages 130-137
Ko Yoshida and Shoji Motomizu

Abstract: The method of Motomizu et al., (Anal. Abstr., 1989, 51, 4B13) is simplified to enhance the sensitivity. River and tap water samples are analyzed on a column (20 cm x 1 mm) of silica gel (100 to 200 mesh) with 0.5 mM Li acetate - 2.5 mM benzo-18-crown-6 as eluent (0.8 mL min-1). The eluate is passed through an anion exchanger membrane tubing (1 ml) and the alkaline stream (pH 10) is extracted with benzene - chlorobenzene (1:1) containing 0.3 mM tetrabromophenolphthalein ethyl ester and 2 mM dicyclohexano-24-crown-8 in an extraction coil (2 m x 0.5 mm) and separated with use of a phase separator with a 0.8 µM-PTFE porous membrane. The absorbance of the organic phase is measured at 615 nm. Beer's law is obeyed for up to 0.5 mM Na and 0.1 mM K. The sampling rate is 12 h-1.
Sodium Potassium Ion exchange Spectrophotometry Sample preparation Silica gel Column Sensitivity Crown ether Extraction Phase separator Teflon membrane Organic phase detection

"Evaluation Of Flow Injection Analysis Method For Total Water Hardness Using A Copper(II) Ion Detector And Correlation With Japanese Industrial Standard Method"
J. Flow Injection Anal. 1991 Volume 8, Issue 2 Pages 148-159
Aki SAKAI, Akihide HENMI, Satoshi ITO, Yasukazu ASANO and Yoshito FUSHINUKI

Abstract: To assay tap-water, river water or industrial boiler water, a 200 µL sample is injected into a stream of water and carried to a reaction tube (500 cm x 0.5 mm) to mix with streams of 0.01 M EDTA - 0.01 M Cu(NO3)2 - 1 mM triethylenetetramine and 0.5 M KNO3 (all streams at 0.9 mL min-1) before detection with a Cu2+-selective electrode (structure of flow cell and electrode shown). The calibration graph is rectilinear for 0.1 to 0.6 mM Ca2+, and the detection limit is 25 µM. Average coefficient of variation is 3%. The method shows good response to both Ca2+ and Mg2+. Interference from Fe2+, Zn2+ and Ba2+ is observed. Sampling rate is 30 h-1. Results are satisfactory and correlate well with those obtained by the Japanese industrial standard method.
Hardness Electrode EDTA Interferences Standard method

"Determination Of Trace Cyanide Ion In Environmental Samples By Flow Injection Analysis With Chemiluminescence Detection At Low Temperature"
J. Flow Injection Anal. 1993 Volume 10, Issue 1 Pages 48-55
Etsu Yamada, Chie Hamamura*, Kazushi Fukuda* and Masanori Sato*

Abstract: The cited determination (diagram of the FIA system given) was carried out at 5°C. Samples were injected into a carrier stream of water (3.1 ml/min) which merged with pre-mixed streams (1.3 ml/min) of NaOH and uranine/didodecyldimethyl ammonium bromide, which had passed through a 1 m mixing coil. The chemiluminescence of the mixture was then recorded. The calibration graph was linear from 0.001-0.1 ppm and 0.01-0.5 ppm of cyanide, for sample volumes of 100 and 20 µL, respectively. The RSD was 3.1% for 0.05 ppm of cyanide. Interferences from co-existing anions are listed. Recoveries of cyanide from river water and waste water samples were 63.8-98.2%.
Cyanide Chemiluminescence Interferences

"Flow Injection Spectrophotometric Determination Of Trace Amounts Of Fluoride Based Upon Its Inhibitory Effect On The Zirconium(IV)-catalysed Peroxoborate-iodide Reaction"
J. Flow Injection Anal. 1996 Volume 13, Issue 1 Pages 35-43
Yonehara, N.;Chaen, S.;Matsumoto, K.;Tomiyasu, T.;Sakamoto, H.

Abstract: Sample (300 µL) was injected into a carrier stream of water at 3 ml/min in a flow injection manifold (schematic shown) and carried to a reaction coil (3 m x 0.5 mm i.d.) where it was mixed with successive reagent streams of 12 mM peroxoborate solution, 0.29 M KI and 0.11 mM zirconium(IV) chloride in 0.9 M HCl (all flowing at 0.5 ml/min). The absorbance of the colored product formed was measured, with [and without the presence of fluoride (I)] at 350 nm. The absorbance intensity reduction was linear for concentrations of 4-100 µg/l of I. The RSD (n = 10) was 1.9% for 5 µg/l of I. Positive interference was observed from 1 mg/l sulfate, phosphite and As(V), and negative one from 0.01 mg/l nitrite. The method was applied to the analysis of river water with recoveries of 92-104%.
Fluoride Spectrophotometry Interferences

"Determination Of Phosphate Utilizing Fluorescent Reaction Of Thiamine With Molybdovanadophosphate By Flow Injection Analysis"
J. Flow Injection Anal. 1998 Volume 15, Issue 2 Pages 234-240
Kishida, M.;Aoki, T.

Abstract: A fluorescence (FL) reaction between thiamine and molybdovanadophosphate was applied to a determination of phosphate by flow injection analysis (FIA). Phosphate was detected by measuring FL intensity of fluorophore produced by reaction of thiamine with molybdovanadophosphate. Under the condition of 1.0 x 10^-3 M vanadate, 1.8 x 10^-2 M sulfuric acid; 1.0 x 10^-3 M molybdate, and 7.5 x 10^-6 M thiamine, the calibration curve for the determination of phosphate was proportional in the concentration. range of 5.0 x 10^-7 M to 2.0 x 10^-5 M. The relative standard deviations (n = 5) at 1.0 x 10^-6 M and 1.0 x 10^-5 M were 5.0% and 2.0%, respectively. The time required to a peak after sample injection was 2 min. The addition of vanadate enabled the removal of interference from silica and increased more than 50 times the sensitivity for the determination of phosphate.
Phosphate Fluorescence Interferences Method comparison Sensitivity

"Method For Determination Of Phosphate In Water With Malachite Green And Application To Environmental Waters"
J. Flow Injection Anal. 1998 Volume 15, Issue 2 Pages 220-224
Aoki, A.;Sato, K.;Tamura, K.;Tanaka, Y.

Abstract: Flow injection analysis for phosphate in water with molybdate and malachite green was presented. Addition of Tergitol as neutral detergent could suppress increase in baseline due to adsorption of ion-pair of molybdophosphate and malachite green on flow cell in spectrophotometer. The calibration curve was proportional in the concentration. of 2 x 10^-5 to 2 x 10^-5 M. The detection limit derived from 8 standard deviation at 2 x 10^-5 M was 5 x 10^-5 M. The tile required to 8 peak after sample injection was 1.35 min. The present method was not interfered from silicate at 1 x 10^-4 M. We applied this method to determine phosphate in river waters. A good match was found for the concentrations. determined by the present method and the molybdenum blue method.
Phosphate Spectrophotometry Surfactant Interferences

"Dynamics Of Anionic Surfactants In River And Creek Waters Of Saga City (Japan)"
Nippon Eiseigaku Zasshi 1984 Volume 39, Issue 4 Pages 787-792
Yukio Hirai, Naomi Koga, Tohoru Hasegawa, Katsumaro Tomokuni1

Abstract: A convenient screening method for tracing the amount of anionic surfactants (AS) in environmental water was developed by applying flow injection analysis (FIA) technique, a simple technique for the automation of wet chemical analyzes, to the new solvent extraction spectrophotometry of AS. AS in gt 140 points of river and creek waters were determined by employing the screening method to assess the AS pollution of Saga City. The AS pollution was divided into four stages: slightly polluted water, 0-0.1 ppm (as sodium dodecylsulfate); polluted water, 0.1-0.5 ppm; highly polluted water, 0.5-1.0 ppm; and extremely polluted water; >1.0 ppm. About 70% of all samples contained >0.1 ppm AS. The main contaminator was assumed to be the AS in waste water from houses. The AS concentration in all streams in the city tended to increase from upstream to downstream. The dynamics of AS were also investigated by monitoring the fluctuation of AS concentration for 24 h and 10 days.
Surfactants, anionic Spectrophotometry

"Analysis Of Nitrate-nitrogen And Total Nitrogen. Improvement Of Copper-cadmium Method"
Kumamotoken Eisei Kogai Kenkyujoho 1987 Volume 1987, Issue 16 Pages 53-54
Kitaoka, H.;Sugimura, T.;Oda, T.;Nakamura, T.

Abstract: Exptimental results of the determination of NO3- and total N in river and seawater by Cu-Cd reduction method are reported. The method was adopted to flow injection system. (SFS)
Nitrate Nitrogen, total Spectrophotometry Sensitivity

"Rapid, Small-volume, Flow Injection Analysis For ΣCO2 And NH4+ In Marine And Freshwaters"
Limnol. Oceanogr. 1992 Volume 37, Issue 5 Pages 1113-1119

Abstract: ΣCO2 (total dissolved inorganic C) and NH4+ in natural waters can be rapidly (~60 samples/h), precisely (~1% relative standard deviation), and simply determined in small samples (20 µL, ΣCO2; 50 µL, NH4+) with an inexpensive flow injection analysis system (FIA). A gas-permeable membrane is used to remove CO2 or NH3 from acidic (ΣCO2) or basic (NH4+) reagent streams into a receiving stream and conductivity detector. Linear negative responses occur over a wide range of concentrations (<0.1-20 mM ΣCO2; 0.1-100 µM NH4+). Adding Zn2+ to sulfidic samples prevents H2S interferences for CO2 and allows determination of H2S at high concentrations (>0.1 mM) by difference (with, without Zn). Interferences from fatty acids (ΣCO2) and methylamines (NH4+) are unlikely at natural levels. These methods correlate well with traditional techniques.
Carbon dioxide Ammonium Conductometry Small sample Interferences Method comparison

"Determination Of Dissolved Manganese In Seawater By Flow Injection Analysis With Colorimetric Detection"
Limnol. Oceanogr. 1993 Volume 38, Issue 6 Pages 1290-1295

Abstract: A flow injection technique for the determination of dissolved Mn in seawater and other natural waters has been developed. The technique utilizes the Mn-catalyzed oxidation of tiron by peroxide. The reaction product is determined colorimetrically. Sensitivity is enhanced and salt effects minimized through on-line pre-concentration of Mn. For a 3 mL sample, a detection limit of 40 pmol kg-1 is possible. Use of a lab-built colorimetric detector can provide an inexpensive alternative to a commercial flow-through spectrophotometer.
Manganese Spectrophotometry Preconcentration Indirect Interferences

"Determination Of Alkaline Phosphatase-hydrolyzable Phosphorus In Natural Water Systems By Enzymatic Flow Injection"
Limnol. Oceanogr. 1994 Volume 39, Issue 8 Pages 1993-2000

Abstract: The method involves use of immobilized Escherichia coli alkaline phosphatase, which produces orthophosphate from phosphate monoesters, nucleoside polyphosphate, deoxynucleoside polyphosphate, inorganic pyro-phosphate, tripolyphosphate, and some S-phosphorothioate esters. The liberated orthophosphate is subsequently detected as phosphomolybdenum blue. Suppression of E. coli alkaline phosphatase activity is significantly reduced when the enzyme is immobilized and used in a packed-bed reactor. This method offers a means of characterizing organic P compounds in the dissolved nutrient pool and has been successfully applied to the study of freshwaters, wastewaters, and sediment extracts. Phosphatase-hydrolyzable P has potential use as an indicator of bioavailability of dissolved P other than orthophosphate in natural waters.
Phosphorus Spectrophotometry Enzyme

"Determination Of Dissolved Vanadium In Natural Waters By Flow Injection Analysis With Colorimetric Detection"
Limnol. Oceanogr. 1998 Volume 43, Issue 3 Pages 526-529
Shiller, Alan M., Lunjin Mao, and Jeram&eacute; Cramer

Abstract: A flow injection technique for the determination of dissolved V in natural waters utilizes the V-catalyzed oxidation of Bindschedler's green leuco base by bromate with tiron and tartrate as reaction activators. The reaction product is quantified colorimetrically. A chelator column of immobilized 8-hydroxyquinoline reduces matrix effects but can be eliminated if samples with a constant matrix are being analyzed. Using the chelator column, 1 mL of sample can be analyzed in <10 min with a detection limit of 0.2 nM. The method was used for the determination of dissolved V in river and estuarine waters.
Vanadium Spectrophotometry Chelation 8-Hydroxyquinoline

"Determination Of The Aluminum Complexing Capacity Of Fulvic Acids And Natural Waters, With Examples From 5 New-zealand Rivers"
Mar. Fresh. Res. 1996 Volume 47, Issue 1 Pages 11-17
DJ Hawke, KJ Powell and JE Gregor

Abstract: An FIA technique with 7 s reaction time was used to analyze free plus labile Al in fulvic acid (FA) solutions and natural waters at pH 4.7, without the need for separation procedures. Titrations of these solutions using incremental pH or total Al were used to determine pH binding curves or estimates of the 'kinetic' Al complexation capacity (Al-CCk) respectively. The operational definition of Al-CCk relates to the capacity of a humic substance or natural water to bind Al through a 7-s FIA reaction time under defined experimental conditions of chromophore (GAS) concentration, ionic strength, and pH. Both Al binding strength and complexation capacity were greater than the corresponding Cu-CC (ISE) values. The Al-CCk measurements at pH 4.7 were 710 µmol Al g-1 v. 590 µmol Cu g-1. Al-CCk results (pH 4.7) were higher for soil FA (710 µmol g-1) than for aquatic FA (390 µmol g-1). AI-CC, results (pH 4.7)for five unfiltered river waters from different catchments gave results in the range 6.5-9.8 µmol Al L-1. The differences between total (natural) Al in the samples and Al-CCk were between 2.7 µM and 8.6 µM. Filtration experiments identified fractionation patterns between total (natural) Al and the fraction of Al-CCk not utilized. The Al titration of alginate, another component of natural organic matter, is reported.
Aluminum Alginate Voltammetry Speciation Complexation Speciation Titrations

"Automated Monitoring Of Nickel, Copper, And Zinc In The Irish Sea"
Mar. Pollut. Bull. 1996 Volume 32, Issue 6 Pages 471-479
Eric P. Achterberg* and Constant M. G. van den Berg

Abstract: The distributions of Ni, Cu and Zn have been monitored in the Irish Sea using fully automated voltammetric instrumentation and collection of seawater by underway pumping. The continuous real-time measurements provided high resolution data with a minimum risk of sample contamination, The surveys showed that the River Mersey was a significant contributor of Ni, Cu and Zn to the eastern Irish Sea and that the trace metal distribution was consistent with an anti-clockwise residual water movement in the eastern Irish Sea. The automated instrumentation is very useful for monitoring requirements for environmental impact assessments and can provide high resolution trace metal data for marine modeling purposes. Copyright (C) 1996 Elsevier Science Ltd,[16 References]
Metals, trace Cadmium Copper Iron Nickel Voltammetry Remote instrument

"Sensitive Amperometric Flow Injection Determination Of Chloride Utilizing The Silver Iodate Immobilized Column And Its Application To River Water Analysis"
Nippon Kagaku Kaishi 1990 Volume 1990, Issue 4 Pages 385-390
Satake, H.;Ikeda, S.

Abstract: The 0.2 M AgIO3 immobilized column (20 cm x 1 mm) is prepared from 63% AgIO3 and poly(vinyl chloride) resin (0.2 to 0.5 mm grain). For application, a 20 µL river water sample is directly injected into the flow injection analyzer. (diagram illustrated), through the AgIO3 column to the mixing coil with a carrier stream of 2 mM H2SO4 and 60% methanol (0.9 mL min-1) to mix with 0.8 M HBr (at 0.54 mL min-1) before amperometric detection of Cl- at +0.3 V at a Ag electrode. The coefficient of variation is 3%. Most co-existing ions do not interfere whereas Mg and Ca require removal before analysis. Calibration graph is rectilinear for 0.5 to 3 ppm of Cl-. Results agreed with those obtained by ion chromatograpy.
Chloride Amperometry Electrode Sensitivity Column Resin Mixing coil Interferences Immobilized reagent Method comparison

"Flow Injection Analysis Of Magnesium In Natural Water Using Eriochrome Azurol B"
Nippon Kaisui Gakkaishi 1991 Volume 45, Issue 2 Pages 78-82

Abstract: Sample was mixed with methanolic 1% eriochrome azurol B (C.I. Mordant Blue 1) solution and 2 mM hexadecyltrimethylammonium chloride and the absorbance of the mixture was measured at 635 nm. The calibration graph was rectilinear from 0.2 to 1 mg L-1 of Mg with coefficient of variation of 1% for determination of 1 and 0.5 mg L-1 of Mg. Results agreed well with those obtained by AAS; Ca interfered but the concentration. of Sr, Ba, Na, K, Cl-, NO3- and SO4- found in river and seawater did not.
Magnesium Spectrophotometry Interferences Method comparison

"Determination Of Indium In Natural Waters By Flow Injection Inductively Coupled Plasma Mass Spectrometry"
Proc. Indian Acad. Sci. 1998 Volume 107, Issue 4 Pages 359-366

Abstract: Two methods were developed to measure In in natural waters by flow injection inductively coupled plasma mass spectrometry (ICP-MS). One is the isotope dilution technique using an 113In enriched spike and the other utilizes natural Y present in the sample as an internal standard In the former, optimization of the 113In spike to minimize error is often difficult for samples in which In concentrations are variable, whereas in the latter method, a sep. determination of Y in the sample is necessary and hence more sample is required. Using ≈1 L of a water sample, 200-fold pre-concentration of In was performed by solvent extraction and back extraction technique and then introduced into the ICPMS to measure the 113In/115In or 115In/89Y ratios. The detection limits were 0.01-0.02 pmol kg-1 for both methods. Application of the methods to seawater samples yielded the concentrations of 0.06-0.15 for the Pacific and 0.6-1.5 pmol kg-1 for the Atlantic. The large inter-oceanic variation of In best resembles that of Al amongst the 3B group of elements in the periodic table. River and estuarine samples gave a more variable range of concentrations of 0.01-15 pmol kg-1. Most of the In supplied by rivers is removed by scavenging in the estuarine mixing zone, suggesting that the fluvial input of In to the ocean is small.
Indium Mass spectrometry Mass spectrometry Sample preparation Optimization Calibration

"Analytical Methodology For The Determination Of Aluminum Fractions In Natural Fresh Waters"
Pure Appl. Chem. 1996 Volume 68, Issue 8 Pages 1597-1638
N. Clarke, L.-G. Danielsson and A. Sparen

Abstract: The distribution among different species, ''speciation'', is essential for understanding the toxicity, bioavailability and transport mechanisms for elements in the natural environment. The distribution of Al among different species has been in focus during the last twenty years or so, and many methods for fractionating Al have been developed. Most of them are operationally defined, since validation of what is really measured in natural systems is very difficult. This review is a thorough and critical survey of the existing methods for Al fractionation in natural waters, that covers the literature up to and including June, 1994. The methods have been classified into six groups, according to the principles used: 1) Kinetic or Binding Strength Discriminations; 2) Ion Chromatographic Separations; 3) Size Exclusion; 4) Non-Invasive Methods; 5) Ion Mobility in an Electric Field; 6) Minimized Disturbance. In addition to this, in order to validate the different techniques, we scrutinize some of the method comparisons published.
Aluminum Chromatography HPIC SEC Nuclear magnetic resonance Chelation Speciation Review

"Determination Of Total Mercury Concentration In Waste Water By Continuous Micro-flow Analysis With Cold Vapor Atomic Absorption Spectrometry"
Sci. Total Environ. 1990 Volume 99, Issue 1-2 Pages 205-209
Edison Munaf*, Hiroki Haraguchi and Daido Ishii, Toyohide Takeuchi, Masashi Goto

Abstract: The method of Goto et al. (cf., Fresenius' Z. Anal. Chem., 1988, 332, 745) was applied in the determination of sub ppm levels of total Hg in river-water and waste water.
Mercury Spectrophotometry

"Interfacing HPLC And Cold Vapor AA With Online Preconcentration For Mercury Speciation"
Spectrosc. Lett. 1991 Volume 24, Issue 5 Pages 681-697
J. C. Gaston Wu

Abstract: A quartz reaction vessel is designed and constructed to interface HPLC and cold-vapor AA for mercury speciation in aqueous samples. Inorganic mercury, methyl mercuric and ethyl mercuric compounds can be separated effectively within 10 minutes. An on-line pre-concentration unit is used to reduce the limit of detection (LOD) before the sample is introduced into the reversed-phase HPLC. Without pre-concentration, the detection limits for the three mercury species are 0.094, 0.085 and 0.124 ppm, respectively. Limits of detection are reduced to 0.78, 0.78 and 0.42 ppm, with the use of pre-concentration technique. The feasibility of this method is tested by analyzing mercury compounds in synthetic tap and river water samples.
Mercury HPLC Spectrophotometry Interface Preconcentration Speciation

"Continuous-flow Method For Determination Of Total Trihalomethanes In Drinking Water With Membrane Separation"
Water Res. 1989 Volume 23, Issue 6 Pages 739-742
Toyoaki Aoki and Kouji Kawakami

Abstract: The trihalomethanes, CHCl3, CHCl2Br, CHClBr2 and CHBr3 were determined by mixing the water sample with 10% NaSO3 solution and passing the mixture through a double tube system at 50°C. The inner tube comprised microporous PTFE and the outer tube was of PTFE. The volatile trihalomethanes passed into the inner tube which contained 0.2 M NaOH, the solution was mixed with 30% nicotinamide solution and the mixture was passed to a reaction coil at 98°C. The reaction product was cooled in an ice bath and determined fluorimetrically at 467 nm (excitation at 372 nm). There was no interference from species in drinking or river waters using this membrane separation system. The detection limit for CHCl3 was 0.8 µg l-1, and the coefficient of variation was 4.4% for 20 µg L-1 (n = 5).
Chloroform Bromodichloromethane Chlorodibromomethane Bromoform Fluorescence Interferences Membrane Detection limit Heated reaction

"Aquatic Soluble Unreactive Phosphorus: HPLC Studies On Concentrated Water Samples"
Water Res. 1995 Volume 29, Issue 9 Pages 2138-2148
Mark A. Nanny*, Seungdo Kim and Roger A. Minear*

Abstract: Soluble unreactive phosphorus (SUP) in concentrated forest stream (Walker Branch, Tenn.) and lake water (Crystal Lake, Ill.) samples was analyzed with an anion-exchange high performance liquid chromatography (HPLC) system containing a phosphorus-specific detector. The detector, which utilized the ascorbic acid-molybdate reaction, consisted of a flow injection system, a post-column reactor, and a u.v.-vis detector. Before HPLC analysis, samples were concentrated and molecular size fractionated with a series of ultrafiltration and reverse osmosis membranes. The SUP composition was found to be a function of season in both Crystal Lake and Walker Branch, as well as a function of stream length for Walker Branch. Seasonal and spatial SUP variations could be explained using contemporary knowledge of nutrient cycling in streams and lakes. A signal, seen in many of the HPLC traces and which eluted with the solvent front, was characterized but not fully identified using several extraction and degradation methods, as a function of sample concentration.
Phosphorus HPLC Spectrophotometry Post-column derivatization

"Flow Injection Analysis. Photometric Determination Of Lead Using Sorption Preconcentration"
J. Anal. Chem. 1988 Volume 43, Issue 12 Pages 2213-2220
Novikov, E.A.;Shpigun, L.K.;Zolotov, Y.A.

Abstract: A five-channel flow injection system (based on a Tecator analyzer.) is used for determining 1 to 100 ng mL-1 of Pb in water. The Pb is pre-concentrated online on a 40 to 70 µL column packed with Chelex-100 (0.15 to 0.3 mm; NH4+ form); the sample stream (4.3 mL min-1) is merged with an ammonium acetate buffer of pH 8.5 (0.6 mL min-1) before entering the column. The sample is pumped for 90 to 600 s the column is then washed with 1 M ammonium acetate of pH 5 to 5.5 (4.3 mL min-1) for 1 to 2 min (to remove the retained Mg and Ca) and, finally, the Pb is eluted by 0.5 M HNO3 (2.8 mL min-1) for 30 s. The eluate is merged successively with a stream of 10% KCN (0.4 mL min-), to mask Cd, Ni, Zn, Cu and Fe, and a reagent stream (0.8 mL min-1) of pH 9.8 containing 0.5 mM 4-(2-pyridylazo)resorcinol(I), 5.7 M NH4Cl and 8.6 M NH3; the transient absorbance signal of the Pb - I complex is measured at 525 nm. The coefficient of variation was 3.5% (n = 3) for ~10 ng mL-1 of Pb in river water.
Lead Spectrophotometry Chelex Preconcentration Tecator

"Bead-injection Determination Of Total Mercury In River Water Samples"
Anal. Sci. 2003 Volume 19, Issue 12 Pages 1653-1657
Raquel P. Sartini, Eliane C. Vidotti And Cl&aacute;udio C. Oliveira

Abstract: A bead-injection system is proposed for total mercury determination in river-water samples. The procedure is based on the introduction of a defined quantity of a resin suspension in the flow system. The selected beads are packed inside of a flow cell and the formed resin mini-column constitutes the optical path. The sample volume is then selected, and its passage by the mini-column allows retention of the mercury ions on the surfaces of the beads. The introduction of a spectrophotometric reagent in the flow system leads to the formation of a colored Hg-dithizone complex on the surface of the bead, which is spectrophotometricaly monitored. The spent beads are directed to waste, allowing the system to become ready to process another sample. The proposed system handles about 20 measurements per hour, consuming 1000 µl of the sample, 1 mg of Chelex 100 resin and 1.25 µg of Dithizone per determination. When 1000 µl of the sample is injected, a linear analytical curve is obtained (A = 0.0052[Hg] + 0.1028, from 0 up to 30 µg l-1, R2 = 0.995); the detection limit is estimated to be 0.9 µg l-1. The results are precise, RSD < 9%; spiked sample recoveries within 91.2 and 109% are found.
Mercury Spectrophotometry Sequential injection Resin Solid phase detection Optosensing Optimization Interferences

"Flow Injection Determination Of Humic Acid With Chemiluminescence Detection"
Anal. Lett. 2005 Volume 38, Issue 14 Pages 2439-2447
Yuhong Tian, Qi Jun Song, Zhaozhe Hua

Abstract: A very sensitive and fast flow injection chemiluminescence method, based on the oxidation of humic acid (HA) by 1,3-dibromine-5,5-dimethylhydantion in the presence of glycine in alkaline medium, was developed for the determination of trace humic acids in water. A wide calibration range from 0.001 to 1.0 µg mL-;1 was obtained at the optimized conditions and the detection limit was as low as 0.5 ng mL-;1 of humic acids. Most of the foreign substances tested showed relatively high tolerance levels and the proposed method was successfully applied to the determination of humic acid in river water and tap water.
Acids, humic Chemiluminescence Interferences Optimization

"On-line Preconcentration And ICP Determination For Trace Metal Analysis"
Microchim. Acta 1989 Volume 99, Issue 3-6 Pages 247-255
Valerio Porta, Corrado Sarzanini and Edoardo Mentasti

Abstract: The use of a closed-loop on-line enrichment procedure in combination with an ICP plasma emission spectrometer has been developed for the analysis of trace metal ions, such as Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. The procedure utilizes a pre-concentration column filled with an anion exchange resin and 8-hydroxy-7-iodoquinoline-5-sulphonic acid is added to the sample prior to pre-concentration. Details on the optimization of pretreatment and instrumental conditions are described. Results obtained for the analysis of river water and antarctic seawater are reported.
Cadmium Chromium Copper Iron Manganese Nickel Lead Zinc Spectrophotometry Preconcentration Column Resin Closed loop

"Determination Of Trace Molybdenum In Water Samples By Electrothermal Atomic Absorption Spectrometry After Preconcentration With Miniaturized Coprecipitation"
Bull. Chem. Soc. Jpn. 1999 Volume 72, Issue 1 Pages 43-46
Tokuo Shimizu, Hirobumi Ito, Hiroshi Kawaguchi and Yoshio Shijo

Abstract: Miniaturized coprecipitation with hydrous manganese(IV) oxide was studied for the pre-concentration of sub µg dm-;3 levels of molybdenum in water samples. Manganese(IV) oxide was produced by a reaction of permanganate ion with ethanol in the presence of 0.1 mol dm-;3 hydrochloric acid. A nanogram amount of molybdenum in a 10 mL sample was quantitatively coprecipitated. The amount of manganese required was 0.1-0.40 mg for a 10 mL sample. The precipitate was collected on a 10 µm membrane filter, and then dissolved in 50 mm3 of 5.6 mol dm-;3 nitric acid and 75 mm3 of 1% hydrogen peroxide. An 80-fold pre-concentration factor was obtained by this procedure. The molybdenum concentration was determined by electrothermal atomic absorption spectrometry using a pyrolytic graphite coated cuvette. The detection limit (3s) was found to be 8.9 ng dm-;3. The proposed method was successfully applied to river water and snow samples.
Molybdenum Spectrophotometry Coprecipitation

"Photodissociation/gas-diffusion Separation And Fluorimetric Detection For The Analysis Of Total And Labile Cyanide In A Flow System"
Fresenius J. Anal. Chem. 1999 Volume 365, Issue 6 Pages 516-520
E. Miralles, R. Compa&ntilde;&oacute;, M. Granados, M. D. Prat

Abstract: Total cyanide species are determined in a flow injection system which includes UV-photodissociation, gas-diffusion separation and spectrofluorimetric detection. Without the irradiation step, only cyanide easily released in acid medium, i.e. labile cyanide, is determined. Cyanide diffuses through a microporous PTFE membrane from an acid donor stream to a sodium hydroxide acceptor stream. Then, the transferred cyanide reacts with o-phthalaldehyde and glycine to form a highly fluorescent isoindole derivative. Complete cyanide recoveries were obtained for the most important metal cyanide complexes found in environmental samples, excepting cobaltocyanide. The sampling frequency for total cyanide was 4 samples h-1 and the detection limit was 0.4 µg L-1. Recoveries of total cyanide from river water obtained with this method are about 90% of those obtained with APHA Method 4500-CN C for total cyanide.
Cyanide, total Fluorescence Method comparison Gas diffusion Teflon membrane UV reactor

"Determination Of Traces Of Arsenic And Selenium By Hydride Generation-atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1985 Volume 321, Issue 5 Pages 464-466
Hisatake Narasaki

Abstract: Hydrides evolved in the mixing coil were stored at a pressure of up to 0.4 atm in a separating funnel and swept into an electrically heated furnace. This process caused effective reduction of the hydride forming elements and minimized the consumption of the reagents. A decrease in the sensitivity by deterioration of the furnace was not observed, because traces of water were introduced into it. The sensitivities at 1% absorption for As(V) and Se(IV) were 0.2 ppb and 0.6 ppb, respectively. Accuracies checked with biological standard reference materials were within the certified values. The proposed method was applied for the determination of arsenic and selenium in river water.
Arsenic Selenium Spectrophotometry Volatile generation