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

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Water

Classification: Water -> drinking

Citations 359

"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

"Kinetic-spectophotometric Determination Of Hydrazine By The Inhibition Of The Bromate-hydrochloric Acid Reaction"
Anal. Chim. Acta 2000 Volume 419, Issue 1 Pages 101-106
Abaas Afkhami and Akbar Afshar-E-Asl

Abstract: A simple, sensitive, accurate and selective method for rapid determination of hydrazine is described which is based on its inhibition effect on the reaction between bromate and hydrochloric acid. The decolorisation of methyl orange by the reaction products was used to monitor the reaction spectrophotometrically at 525 nm. The method allows the determination of hydrazine in the range 3.0 x 10^-7-3.2 x 10^-5 M. The relative standard deviation for 10 determinations of 6.25 x 10^-6 M hydrazine is 1.2% and the detection limit of the method is 8.5 x 10^-8 M. The method is applied to the determination of hydrazine present in water.
Hydrazine Spectrophotometry Kinetic Indirect

"Standard Addition Method In FIA. Comparison Between Different Assemblies"
Anal. Chim. Acta 1999 Volume 379, Issue 1-2 Pages 89-97
P. Campíns-Falcó, F. Bosch-Reig and F. Blasco-Gómez

Abstract: A comparison between the different proposed methods to perform the standard addition in an online way (flow injection analysis) is made. The different assemblies (reverse and conventional FIA) and the employed standards in every method are compared. Three analyzes were carried out, two of them were analyzes of samples of pH indicators (methylorange and chlorophenol red) prepared at an acid pH, while the standards were prepared at a basic pH. The third analysis was the analysis of chloride in different synthetic waters with a perfectly known composition for all the ions present in the samples. Besides a new method to perform the online standard addition is proposed, trying to reduce the consumption of reagents and sample. This new method makes use of a 6-port multiposition valve electrically actuated.
Methylorange Chlorophenol Red Chloride Spectrophotometry Standard additions calibration Manifold comparison Reverse

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

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

"Fast Sequential Injection Determination Of Benzo[A]pyrene Using Variable Angle Fluorescence With On-line Solid-phase Extraction"
Analyst 2001 Volume 126, Issue 4 Pages 451-456
J. A. Erustes, A. Andrade-Eiroa, A. Cladera, R. Forteza and V. Cerdà

Abstract: A methodology for the analysis of drinking water for one of the most potent carcinogenic agents known; benzo[a]pyrene (BaP), in the presence of other interfering PAHs is presented. The methodology described is based on the sequential injection analysis of the sample on to a microcolumn (containing 5 mg of C-18) where extraction and pre-concentration of BaP takes place, followed by elution of BaP with 1 mL of 1,4-dioxane and subsequent detection by using variable angle fluorescence. The advantages of the method include the small amount of stationary phase employed together with the possibility of re-using the phase in order to carry out a large number of injections without the need for column re-packing. Also noteworthy is the small volume of 1,4-dioxane used to elute the BaP retained on the column and the small sample volumes required (9-10 mL) for achieving detection limits at the ng L-1 level. Thus, a methodology for BaP determination is obtained which complies with the requirements of the 98/83/EC Directive which fixes a maximum admissible concentration for this pollutant in waters for public consumption of 10 ng L-1. The variable angle spectra obtained are further processed by means of the multiple linear regression technique. The detection limit for BaP is 2.5 ng L-1, and the linear range is between 7.5 and 280 ng L-1.
Benzo(a)pyrene Fluorescence C18 Column Sequential injection Preconcentration

"Sequential Injection Analysis For The Determination Of Fuberidazole And Thiabendazole By Variable-angle Scanning Fluorescence Spectrometry"
Anal. Chim. Acta 2001 Volume 427, Issue 1 Pages 83-92
G. de Armas, E. Becerra, A. Cladera, J. M. Estela and V. Cerdà

Abstract: A study of the behavior of fuberidazole (FBZ) (2-(2-furyl)benzimidazole), and thiabendazole (TBZ) (2-(thiazol-4-yl)benzimidazoie) in a sequential injection system with a fluorimetric detector has been performed. Several variables such as pH, composition of buffers, volumes of sample and reagents, addition order, geometry of mixing coil and spectrofluorimetric parameters have been optimized. A pH 2 buffer solution was found to be optimal for both FBZ and TBZ. The calibration graphs are linear between 0.04 and 10 µg L-1 for FBZ and between 0.08 and 20 µg L-1 for TBZ with 3s detection limits of 0.012 and 0.02 µg L-1, respectively. The relative standard deviation (n = 10) was 0.3% for 1 µg L-1 of FBZ and 0.5% for 2 µg L-1 of TBZ. Resolution of the system was carried out by applying a multiple linear regression (MLR) calibration model. The method was applied to the determination of both fungicides added to natural waters. Recoveries between 96 and 106% were achieved.
Fuberidazole Thiabendazole Fluorescence Sequential injection Multivariate calibration Optimization

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

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

"Dual Wetting-film Multi-syringe Flow Injection Analysis Extraction - Application To The Simultaneous Determination Of Nitrophenols"
Anal. Chim. Acta 2001 Volume 438, Issue 1-2 Pages 103-116
Manuel Miró, Andreu Cladera, José Manuel Estela and Víctor Cerdà

Abstract: A dual wetting-film extraction/back-extraction system based on a multi-syringe flow injection analysis (MSFIA) set-up coupled to additional burettes and solenoid valves is proposed. The system performs on-line analyte extraction from an aqueous medium to an organic solvent based on the differential flow velocities of the aqueous and organic phases into PTFE tubing, which is due to the formation of a thin and pseudo-stationary organic film adhered to the inner walls of the extraction coil. The pre-concentrated analytes are eluted into a small eluting solution segment and conducted to a diode-array spectrophotometer for analysis. The peak maximum spectrum is used for the simultaneous determination of different analytes by using multi-component analysis with multi-linear regression (MLR). This dual system is applied to the multi-component determination of 2, 3- and 4-nitrophenol. By using 8 mL of sample and 88 µL of 1-chloroburane in 1-octanol (66/34, v/v) as organic phase, a sample throughput of 11 analyzes per hour can be obtained. The detection limits for 2-, 3- and 4-nitrophenol are 0.11, 0.46 and 0.07 muM, respectively, and the relative standard deviations are less than 4%.
2-Nitrophenol 3-Nitrophenol 4-Nitrophenol Spectrophotometry Extraction Multisyringe Simultaneous analysis Preconcentration

"Time-based Multisyringe Flow Injection System For The Spectrofluorimetric Determination Of Aluminum"
Anal. Chim. Acta 2002 Volume 455, Issue 1 Pages 149-157
Graciela de Armas, Manuel Miró, Andreu Cladera, José Manuel Estela and Víctor Cerdà

Abstract: A time-based multisyringe flow injection procedure with spectrofluorimetric detection is proposed in this paper for the determination of aluminum in drinking water. The flow methodology is based on the simultaneous or sequential injection of sample and chelating reagent (viz. 8-hydroxyquinoline-5-sulphonic acid) plugs using a multicommutation approach so that three successive injections may be performed with a sole displacement of the piston driver bar of the burette. Thus, an injection throughput as high as 154 h-1 is achieved by sampling a 182 µL sample zone. In order to enhance the luminescence, the reaction is carried out in micellar medium using hexadecyltrimethylammonium chloride as surfactant. The influence of geometric and hydrodynamic variables as well as several parameters such as multicommutation timing, ligand and surfactant concentration and reagent pH was assessed. Under the selected working conditions, a linear dynamic range from 10 to 500 µg L-1 Al(III). a 3s detection limit of 0.5 µg L-1 and a coefficient of variation of 0.6% at the 30 µg L-1 level were obtained. The analytical features were compared with those reported in previous flow injection and sequential injection methods. The multisyringe technique was successfully applied to the determination of aluminum in drinking water at low mineralisation levels, validating the results by inductively coupled plasma atomic emission spectrometry.
Aluminum(III) Fluorescence Multisyringe 8-hydroxyquinoline-5-sulfonic acid Multicommutation Optimization Method comparison

"Determination Of Chloride By Multisyringe Flow Injection Analysis And Sequential Injection Analysis With Potentiometric Detection"
Anal. Chim. Acta 2002 Volume 467, Issue 1-2 Pages 25-33
A. Andrade-Eiroa, J. A. Erustes, R. Forteza, V. Cerdá and J. L. F. C. Lima

Abstract: This paper reports for the first time a multisyringe flow injection analysis (MSFIA) method with potentiometric detection for the automated determination of chloride in waters. The methodology developed was applied to the determination of chloride in mineral, tap and waste waters and the results achieved were compared with those obtained by a potentiometric sequential injection analysis (SIA) method reported in the literature. When Mohr titration was carried out for validating the results offered by both techniques, no significant differences were found. The linear ranges were between 6 and 3500 µg L-1 for MSFIA and 10 and 3500 mg L-1 for SIA; the UPAC limits of detection were 2.7 mg L-1 for MSFIA and 1.6 mg L-1 for SIA; reproducibility was ~0.8% for MSFIA and 0.4% for SIA and, sampling rates were of 30 and 15 injections h-1 for MSFIA and SIA, respectively. These results provide evidence of superior performance of MSFIA over SIA for the determination of chloride. (C) 2002 Elsevier Science B.V. All rights reserved.
Chloride Potentiometry Electrode Multisyringe Method comparison Sequential injection

"Simultaneous Determination Of Fluorophores With Overlapped Spectra By Sequential Injection Analysis Coupled To Variable Angle Scanning Fluorescence Spectrometry And Multivariate Linear Regression Algorithms"
Anal. Chim. Acta 2002 Volume 471, Issue 2 Pages 173-186
Graciela de Armas, Manuel Miró, José Manuel Estela and Víctor Cerdà

Abstract: An automated and versatile sequential injection spectrofluorimetric procedure for the simultaneous determination of multicomponent mixtures in micellar medium without prior separation processes is reported. The methodology is based upon the segmentation of a sample slug between two different buffer zones in order to attain both an improvement of sensitivity and residual minimization for the whole species. Resolution of overlapping fluorescence profiles is achieved using a variable angle scanning technique coupled to multivariate least-squares regression (MLR) algorithms at both sample edges. The potentialities of the described methodology are illustrated with the spectrofluorimetric determination of four widespread pesticides with different acid-base properties; viz. carbaryl (CBL) (1-naphthyl-N-methylcarbamate), fuberidazole (FBZ) (2-(2-furyl)benzimidazole), thiabendazole (TBZ) (2-(4-thiazolyl)benzimidazole) and warfarin (W) (3-α-acetonylbenzyl)-4-hydroxycoumarin. Detection limits at the 3s level were 3.9, 0.02, 0.03 and 10 µg L-1 for CBL, FBZ, TBZ and W, respectively at the maximum sensitivity pH. Dynamic ranges of 13-720 µg L-1 CBL, 0.10-14 µg L-1 FBZ, 0.19-60 µg L-1 TBZ and 0.05-5 mg L-1 W were achieved. Relative standard deviations (n = 10) were 0.2% for 100 µg L-1 CBL and 2.4 µg L-1 FBZ, 0.7% for 8 µg L-1 TBZ and 1.0% for 1 mg L-1 W. The proposed automated methodology, which handles 17 samples/h, was validated and applied to spiked real water samples with very satisfactory results. (C) 2002 Elsevier Science B.V. All rights reserved.
Carbaryl Thiabendazole Warfarin Fuberidazole Fluorescence Multivariate calibration Sequential injection Simultaneous analysis Automation Micelle

"Fluorimetric Sequential Injection Analysis Of Aluminum In A Micellar Medium"
Quim. Anal. 2002 Volume 20, Issue 4 Pages 211-215
de Armas, G.;Torres, J.R.;Cladera, A.;Estela, J.M.;Cerda, V.

Abstract: This work presents a sequential-injection system for the determination of aluminum in water. The system is based on the spectrofluorimetric detection of the complex formed between 8-hydroxyquinoline-5-sulphonic acid (HQS) and aluminum. The reaction is carried out in a micellar medium using cetyltrimethylammonium chloride as surfactant. The influence of several variables, such as reagent and surfactant concentration and pH, has been investigated. A detection limit of 6 µg L-1 of aluminum was obtained. The method has been applied to a drinking water sample.
Aluminum Fluorescence 8-hydroxyquinoline-5-sulfonic acid Preconcentration Sequential injection Micelle Optimization

"Incidence Of Transitional Cell Carcinoma And Arsenic In Drinking Water: A Follow-up Study Of 8,102 Residents In An Arseniasis-endemic Area In Northeastern Taiwan"
Am. J. Epidemiol. 2001 Volume 153, Issue 5 Pages 411-418
Hung-Yi Chiou, Shu-Ti Chiou, Yi-Hsiang Hsu, Yi-Li Chou, Chin-Hsiao Tseng, Min-Li Wei, and Chien-Jen Chen

Abstract: A significant association between ingested arsenic and bladder cancer has been reported in an arseniasis-endemic area in southwestern Taiwan, where many households share only a few wells in their villages. In another arseniasis-endemic area in northeastern Taiwan, each household has its own well for obtaining drinking water. In 1991-1994, the authors examined risk of transitional cell carcinoma (TCC) in relation to ingested arsenic in a cohort of 8,102 residents in northeastern Taiwan. Estimation of each study subjects individual exposure to inorganic arsenic was based on the arsenic concentration in his or her own well water, which was determined by hydride generation combined with atomic absorption spectrometry. Information on duration of consumption of the well water was obtained through standardized questionnaire interviews. The occurrence of urinary tract cancers was ascertained by follow-up interview and by data linkage with community hospital records, the national death certification profile, and the cancer registry profile. Cox proportional hazards regression analysis was used to estimate multivariate-adjusted relative risks and 95% confidence intervals. There was a significantly increased incidence of urinary cancers for the study cohort compared with the general population in Taiwan (standardized incidence ratio = 2.05; 95% confidence interval (CI): 1.22, 3.24). A significant dose-response relation between risk of cancers of the urinary organs. especially TCC, and indices of arsenic exposure was observed after adjustment for age, sex, and cigarette smoking. The multivariate-adjusted relative risks of developing TCC were 1.9, 8.2, and 15.3 for arsenic concentrations of 10.1-50.0, 50.1-100, and >100 µg/liter, respectively, compared with the referent level of less than or equal to 10.0 µg/liter.
Arsenic Spectrophotometry

"A New Flow Injection System For Spectrophotometric Determination Of Phosphate Ions"
Rev. Roum. Chim. 1999 Volume 44, Issue 8 Pages 771-777
Cheregi, M.C.;Danet, A.F.

Abstract: A flow injection system for determining the phosphate ions in natural, drinking, and residual waters was assembled. It contained an injection device with several mono-channel valves which can be either opened or shut simultaneously. Determination of PO43- ion with this FIA system is done by using the method based on the formation of phosphomolybdenum blue and spectrophotometric detection at 660 nm of the reaction product. The influence of different operational parameters was investigated. The calibration curve was linear over the 1-30 µg PO43- mL-1 domain, the relative standard deviation was 1.8% (n = 10) and the number of samples that could be analyzed was 30 h-1. A study on possibly interfering ions was also carried out. (SFS)
Phosphate Spectrophotometry Interferences Optimization

"Spectrofluorimetric Determination Of Aluminum In Drinking Waters By Sequential Injection Analysis"
Anal. Chim. Acta 2002 Volume 457, Issue 2 Pages 311-318
C. Brach-Papa, B. Coulomb, J. -L. Boudenne, V. Cerda and F. Theraulaz

Abstract: A selective procedure for the determination of Al3+ in drinking and natural waters is proposed, The analytical procedure is based both on the complex formation between Al3+ and 8-hydroxyquinoline-5-sulfonic acid (HQS) and on a fluorimetric detection of the complex. The reaction was carried out in presence of thioglycolic acid as a masking agent. This procedure has been adapted to a sequential injection analysis (SIA) system. Operative conditions both for batch and SIA procedures were investigated including reagent concentration, volumes, pH and wavelengths used for the fluorimetric detection. Batch procedure allows determination of Al3+ at ppb level (LOQ: 2.8 µg L-1) within a working range of 2.2-300 µg L-1. The SIA procedure was successfully employed for the determination of Al3+ in several commercial drinking and tap waters.
Aluminum(III) Fluorescence 8-hydroxyquinoline-5-sulfonic acid Masking agent Optimization Sequential injection

"Silica Gel-immobilized-dithioacetal Derivatives As Potential Solid Phase Extractors For Mercury(II)"
Talanta 2000 Volume 51, Issue 1 Pages 77-87
Mohamed E. Mahmoud and Gamal A. Gohar

Abstract: Dithioacetal derivatives with different para-substituents, X=H, CH3, OCH3, Cl and NO2 were synthesized and chemically immobilized on the surface of silica gel for the formation of five newly synthesized silica gel phases (I-V). Characterization of the silica gel surface modification by the organic compounds was accomplished by both the surface coverage determination as well as the infrared spectroscopic analysis. The metal sorption properties of the silica gel phases were studied to evaluate their performance toward metal-uptake, extraction and selective extraction processes of different metal ions from aqueous solutions based on examination of the various controlling factors. The studied and evaluated factors are the pH effect of metal ion solution on the metal capacity values (mmol g-1), equilibration shaking time on the percent extraction as well as the structure and substituent (X) effects on the determined mmol g-1 values. The results of these studies revealed a general rule of excellent affinity of these silica gel phases-immobilized-dithioacetal derivatives for selective extraction of mercury(II) in presence of other interfering metal ions giving rise to a range of 94-100% extraction of the spiked mercury(II) in the metal ions mixture. The potential application of the newly synthesized silica gel phases (I-V) for selective extraction of mercury(II) from two different natural water samples, namely sea and drinking tap water, spiked with 1.0 and 10.0 ng mL-1 mercury(II) were also studied by column technique followed by cold vapor atomic absorption analysis of the unretained mercury(II). The results indicated a good percent extraction and removal (90-100±3%) of the spiked mercury(II) by all the five silica gel phases. In addition, insignificant contribution by the matrix effect on the processes of selective solid phase extraction of mercury(II) from natural water samples was also evident.
Mercury(II) Spectrophotometry Silica gel Preconcentration Interferences Optimization Reactor

"Flow Injection Analysis Capillary Electrophoresis System With Hydrodynamic Injection"
Anal. Chim. Acta 1999 Volume 378, Issue 1-3 Pages 55-62
Petr Kuban, Reza Pirmohammadi and Bo Karlberg

Abstract: A flow injection analysis-capillary electrophoresis (FIA-CE) system with hydrodynamic injection has been developed. Sample is injected in an electrolyte carrier solution pumped continuously in the FIA part of the system. The interface, connecting the FIA and the CE system moieties, accommodates one end of the separation capillary and a platinum electrode. The other capillary end and the second platinum electrode are immersed in a separate vial containing electrolyte solution. Carrier outflow from the interface is provided by a pinch valve. When the sample plug in the carrier passes the capillary end in the interface, the pinch valve is closed and a fraction of the sample is forced into the capillary. The high voltage supply, shut off during this sample introduction cycle, is then resumed and separation takes place in the capillary. Repeated sample injections in one electrophoretic run are facilitated. The overall repeatability, expressed as relative standard deviation for eight consecutive injections of 50 mg L-1, was about 3%. Quantitative analyzes can be accomplished ~5 times faster than that obtained using conventional CE instrumentation. The developed instrument was used to determine common inorganic cations (Na+, K+, Ca2+, Mg2+) in water and soft drink samples.
Sodium Potassium Calcium Magnesium Electrophoresis Hydrodynamic injection Interface

"Determination Of Nano-molar Levels Of Formaldehyde In Drinking Water Using Flow Injection System With Immobilized Formaldehyde Dehydrogenase After Off-line Solid-phase Extraction"
Anal. Chim. Acta 1999 Volume 378, Issue 1-3 Pages 169-175
Nobutoshi Kiba, Limin Sun, Shinya Yokose, Masaki Tachibana Kazue and Tani Takashi Suzuki

Abstract: Low levels of formaldehyde were determined by pre-concentration with poly(allylamine) beads and analysis by flow injection system with immobilized formaldehyde dehydrogenase. Formaldehyde dehydrogenase was immobilized on tresylate-poly(vinyl alcohol) beads and packed into a stainless-steel column (5 cm x 4 mm). The column was incorporated in a flow injection system with fluorimetic detection. The calibration graph was linear from 0.5 to 10 µM (15-300 µg l-1). The poly(allylamine) beads (0.5 g) were used to adsorb formaldehyde present at 20-400 nM (0.6-12 µg l-1) from drinking water (11). Formaldehyde was eluted with 1 M HCl (10 ml). The solution (50 µl) adjusted to pH 9 was injected into the flow injection system. Concentration factor was 25-fold. Recovery of formaldehyde spiked into purified water was >96% with a relative standard deviation of <3.0%.
Formaldehyde Spectrophotometry Preconcentration Immobilized enzyme Column pH Solid phase extraction

"Selective Pre-concentration And Solid Phase Extraction Of Mercury(II) From Natural Water By Silica Gel-loaded Dithizone Phases"
Anal. Chim. Acta 2000 Volume 415, Issue 1-2 Pages 33-40
Mohamed E. Mahmoud, Maher M. Osman and Mohamed E. Amer

Abstract: Two silica gel phases loaded with dithizone were synthesized based on chemical binding and physical adsorption approaches. The stability of a chemically modified dithizone phase (I) was found to be more superior than that of a physically adsorbed one (II), especially in concentrated hydrochloric acid which was then used as a recycling and pre-concentration reagent for further uses of phase (I). The application of these two silica gel phases for sorption of a series of metal ions was performed by using different controlling factors such as the pH of metal ion solution and the equilibration shaking time by the static technique. For most metal ions, the determined metal capacity values (µmol g-1) were found to be higher in the case of phase (I) as compared to phase (II). This difference was interpreted on the basis of selectivity incorporated in these sulfur containing silica gel phases. Hg(II) was found to exhibit the highest affinity towards extraction by these silica gel phases. The pronounced selectivity was also confirmed from the determined distribution coefficient (K-d) of all the metal ions, showing the highest value reported for mercury(II) to occur by phase (I). The potential applications of phase (I) for selective extraction of mercury(II) to occur from aqueous solution were successfully accomplished as well as pre-concentration of low concentration of Hg(II) (20 pg ml-1) from natural tap water with a pre-concentration factor of 200 for Hg(II) off-line analysis by cold vapor atomic absorption analysis.
Mercury(II) Spectrophotometry Solid phase extraction Dithizone Precipitation Silica gel

"On-line Preconcentration System For Vanadium Determination In Drinking Water Using Flow Injection-inductively Coupled Plasma Atomic Emission Spectrometry"
Anal. Chim. Acta 2000 Volume 420, Issue 1 Pages 73-79
R. G. Wuilloud, J. A. Salonia, J. A. G&aacute;squez, R. A. Olsina and L. D. Martinez

Abstract: An on-line vanadium a pre-concentration and determination system implemented with inductively coupled plasma atomic emission spectrometry (ICP-AES) associated to low flow injection (FI) was studied. For the retention of vanadium, 2- (5-Bromo-2-pyridylazo)-5-diethylaminophenol (5-Br- PADAP) and Amberlite XAD-7 were used, at pH 3.7. The vanadium was removed from the mcirocolumn in countercurrent with nitric acid. An enrichment factor (EF) of 75 was obtained. The detection limit value for the pre-concentration of 50 mL of aqueous solution of vanadium was 0.04 µgl-1. The precision for 10 replicate determinations at the 5 µg L-1 vanadium levels was 2.5% relative standard deviation (R.S.D), calculated with the peak heights obtained. The calibration graph using the pre-concentration system for vanadium was linear with a correlation coefficient of 0.9996 at levels near the detection limited up to at least 50 µgl-1. The method was successfully applied to the determination of vanadium in drinking water samples.
Vanadium Spectrophotometry Preconcentration Extraction Amberlite Reference material Optimization

"A Novel Flow-through Disk-based Solid-phase Extraction Diffuse Reflectance Optrode. Application To Preconcentration And Determination Of Trace Levels Of Nitrite"
Analyst 2001 Volume 126, Issue 10 Pages 1740-1746
Manuel Mir&oacute;, Wolfgang Frenzel, Jos&eacute; Manuel Estela and V&iacute;ctor Cerd&agrave;

Abstract: A novel, versatile and sensitive flow-through optical fiber diffuse reflectance sensor to implement disk-based solid-phase extraction in a flow injection analysis (FIA) system is presented. Nitrite optosensing at trace levels is chosen as a model of chemistry to demonstrate its applicability. The methodology is based on on-line nitrite derivatization with Shinn reagent to form a moderately polar azo dye, whose pre-concentration oil to octadecyl covalently bonded silica gel particles tightly bound to an inert matrix (C-18 disk) is continuously monitored using a plug-in diode-array spectrophotometer. After the analytical signal has been recorded, fast sensor regeneration is achieved with a methanolic eluent, rendering the system ready for the next extraction. Selection of the solid disk support and the suitable flow-through cell configuration to reduce back-pressure effects are discussed in detail. By matching the illumination and retention zones, concentrations of nitrite as low as 1 ng mL-1 are easily determined using 2.5 mL of sample. A detection limit (3s (blank)) of 0.1 ng mL-1 of nitrite, repeatability and reproducibility better than 3.2%, an analytical throughput of 11 h-1 and an enrichment factor of 140 are the figures of merit of the proposed optrode. The utility of the flow-through optosensing system, wherein minimization of additive matrix interferences is feasible, was testified by the satisfactory results obtained in its application to tap, ground, harbor and aquarium water samples.
Nitro compounds Sensor Spectrophotometry Optrode C18 Preconcentration Optimization Interferences

"Solid Phase Extraction Of Trace Metal Ions In Drinking Water Samples From Kayseri-Turkey"
J. Trace Microprobe Tech. 2000 Volume 18, Issue 3 Pages 397-403
Soylak, M.;Elci, L.

Abstract: The concentrations of Ni, Pb, Cd, Cu and Co in drinking water from wells, direct sources or storage tanks in 18 sites of Kayseri (Turkey) were determined by graphite furnace atomic absorption spectrometry, after enrichment on an Amberlite XAD-4 resin to reduce the incidence of contamination. The levels of Ni, Pb, Cd, Cu and Co in the drinking waters were in the range of 2.9 to 9.5, 2.7 to 29.9, 0.7 to 3.1, 2.0 to 21.6 and 2.1 to 6.4 µg/L, respectively. These values for the drinking water supplies of Kayseri City were below the maximum tolerable limits set by the WHO and the Water Pollution Control Regulation of the Turkish authorities. The correlation between metal ions were also calculated.
Nickel Lead Cadmium Copper Cobalt Spectrophotometry Preconcentration Activated carbon Preconcentration Amberlite

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

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

"Construction And Behavior Of A Micro Flow-through Copper(II)-selective Electrode"
Anal. Chim. Acta 1978 Volume 101, Issue 2 Pages 419-422
W. E. Van Der Linden and R. Oostervink

Abstract: Two flow-through Cu2+-selective electrodes (the dismountable and disposable electrodes) were described for the continuous and flow injection determination of Cu2+. The 2 electrodes contain Cu sulfide pellets. The pellet was embedded in Polypol PS 230 polymer by using a polyethylene mould, and the polymer was hardened at 60°C. The dismountable electrode showed a fast response (90% of the max. response value in 6 s). The disposable electrode showed much slower response (90% of the max. response in ~50 s). The disposable electrode was used to monitor Cu in tap water. The determination of 10^-5 M Cu was not affected by the presence of 10^-4 M Co2+, Ni2+, Zn2+, Pb2+, and Cd2+. Fe3+ 10^-4 M showed an interference of <10%.
Copper(II) Electrode Electrode Apparatus Interferences

"Determination Of Cyanides By Continuous Distillation And Flow Analysis With Cylindrical Amperometric Electrodes"
Anal. Chim. Acta 1980 Volume 114, Issue 1 Pages 275-281
B. Pihlar and L. Kosta

Abstract: A continuous system for the determination of free and complex cyanides has been developed. Hydrogen cyanide is released in an acidic solution in a counter-current system operated by a peristaltic pump, absorbed in dilute sodium hydroxide and then fed into the amperometric detector with a cylindrical silver flow-through electrode. The parameters affecting the release and absorption of cyanide, as well as the electrode response and sensitivity, are described. Differentiation between total cyanide and strongly bound metal cyanide complexes is achieved by u.v. decomposition of the complexes.
Cyanides Amperometry Electrode Electrode

"Spectrophotometric Determination Of Magnesium By Flow Injection Analysis With A Ligand Buffer For Masking Calcium"
Anal. Chim. Acta 1983 Volume 149, Issue 1 Pages 291-296
Hiroko Wada, Akio Yuchi and Genkichi Nakagawa

Abstract: 1-(2-Hydroxy-3-sulfo-5-chloro-1-phenylazo)-2-naphthol-3,6-disulfonic acid is used in a spectrophotometric flow-injection system for the determination of magnesium (0.2-2.4 mg l-1) at a sampling rate of 80 h-1. Interference of calcium is eliminated by using a barium-(II)-EGTA ligand buffer. Iron(III), aluminum(III), copper(II), zinc(II), manganese(II) and cadmium(II) are masked by cyanide and triethanolamine. The method is suitable for application to tap and pond waters.
Magnesium Spectrophotometry

"Spectrophotometric Determination Of Traces Of Iron With 2-(3,5-dibromo-2-pyridylazo)-5-(N-ethyl-N-(3-sulfopropyl)amino)phenol And Its Application In Flow Injection Analysis"
Anal. Chim. Acta 1983 Volume 153, Issue 1 Pages 199-206
H. Wada and G. NakagawaK. Ohshita

Abstract: Manual and flow injection methods have been developed based on the reaction of the cited reagent (I) with Fe(II) to form a 2:1 (ligand-to-metal ratio) complex having absorption max. at 568 nm (e = 88,000) and 748 nm (e = 39,000). In the flow injection method, the sample (0.2 ml) is injected into a stream of 0.1% ascorbic acid that is mixed with 0.1 mM I and 1 M NH3 - 1 M NH4Cl buffer solution before the absorbance is measured at 750 nm. The calibration graph is rectilinear for 20 to 440 ng mL-1 of Fe(II). Bivalent Cu, Ni, Co and Zn interfere seriously at 570 nm, but, except for Zn, have little effect at 750 nm; the presence of Zn causes enhancement at 750 nm, but the effect is constant for Zn concentration. in the range 12 to 80 µM. There is no interference from Cl-, I-, NO3-, SO42-, ClO4-, S2O32-, PO43- or F-. The method has been applied to drinking water.
Iron(2+) Spectrophotometry Interferences

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

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

"Synthesis Of O,o'-dihydroxyazo Compounds And Their Application To The Determination Of Magnesium And Calcium By Flow Injection Analysis"
Anal. Chim. Acta 1984 Volume 159, Issue 1 Pages 289-298
H. Wada and G. Nakagawa, K. Ohshita

Abstract: Seven such compounds were synthesized, and were found to be highly sensitive reagents for Mg (e = 47,000) and Ca (e = 39,000). Because of its ease of preparation and purification and its stability in alkaline solution, 4-(4-diethylamino-2-hydroxyphenylazo)-3-hydroxynaphthalene-2,7-disulfonic acid was the preferred reagent. By masking Fe(III), Al, Cu(II), Zn, Mn(II) and Cd with 2,3-dimercaptopropanol(I) and triethanolamine(II), the sum of Mg and Ca was determined. Magnesium was determined alone by masking Ca and the other metals with a ligand buffer containing Ba, 3,6-dioxaoctane-1,8-diamine-NNN'N'-tetra-acetic acid, I and II, and Ca could then be determined by difference. Calibration graphs were rectilinear over the ranges 0.1 to 1.2 mg L-1 (Mg) and 0.4 to 4 mg L-1 (Ca). The method was used to determine Mg and Ca in tap-water and a standard serum; the results compared well with those for the waters obtained by AAS or EDTA titration and with the certified value for the serum. A diagram of the flow injection manifold is given; the PTFE tubing was 0.5 mm in i.d. except for the back-pressure coil (0.25 mm i.d., 50 cm long). The chromogenic reagent and buffer solution were each delivered at 0.81 mL min-1 with a peristaltic pump, and the sample was injected into the buffer stream via a rotary valve. Sample and reagent solution were mixed in a 300-cm coil and passed to a flow cell (10 mm light path; 20 µL volume) for measurement of absorbance.
Calcium Magnesium Spectrophotometry Interferences Method comparison Reference material Chromogenic reagent

"Online Trace Metal Enrichment And Matrix Isolation In Atomic Absorption Spectrometry By A Column Containing Immobilized 8-quinolinol In A Flow Injection System"
Anal. Chim. Acta 1984 Volume 160, Issue 1 Pages 1-10
Fottis Malamas, Mats Bengtsson and Gillis Johansson

Abstract: A flow injection system was developed for the determination of Cu(II), Co(II), Cd, Ni, Pb(II) and Zn, which incorporated their concentration and separation from the sample matrix at pH 6.5. The sample solution or water was passed, via a pneumatically operated, time-controlled injection valve, through a column packed with quinolin-8-ol azo-immobilized on 240 µL of porous glass. An aliquot (400 µL) of 1 M HCl - 0.01 M HNO3 was used to elute the metal ions; the effluent was nebulized for analysis by flame (air - acetylene) AAS Most of the components of the analytical system were constructed from PTFE. Buffer solution was pumped after the injection valve into the flowing stream. The sampling time could also be increased to improve enrichment factors, e.g., 25 min gave 500-fold enrichment from 100 mL of sample solution All the operations were controlled online. The concentration. of Cu(II) in tap-water was determined; results agreed well with those of graphite-furnace AAS
Cadmium Cobalt Copper Lead Nickel Zinc Ion exchange Spectrophotometry 8-Hydroxyquinoline Preconcentration Matrix removal Reactor

"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

"Determination Of Trace Amounts Of Heavy Metals In Waters By A Flow Injection System Including Ion-exchange Preconcentration And Flame Atomic Absorption Spectrometric Detection"
Anal. Chim. Acta 1984 Volume 164, Issue 1 Pages 41-50
Zhaolun Fang, Shukun Xu and Suchun Zhang

Abstract: The flow injection system described (see preceding abstract) has been applied to the determination of Ni, Cu, Pb and Cd. The samples (5 ml) were injected into a stream of 0.1 M ammonium acetate (pH 5.5) via a sampling loop, and the solution was passed through two columns (50 mm x 2.5 to 3 mm) filled with a chelating ion-exchange resin containing a salicylic acid functional group. Elution was effected with 2 M HNO3, and Ni, Cu, Pb and Cd were determined in the eluate by AAS, with absorption measurements at 232.0, 324.8, 283.8 and 228.8 nm, respectively, and use of an air - acetylene flame. At a sampling rate of 40 h-1, the sensitivity was enhanced 20 to 28-fold in comparison with that attained by direct aspiration of the sample solution into the flame. With the exception of Cd, recoveries of the metals from sewage, tap-water and seawater were generally satisfactory; coefficient of variation were generally 4.1% (n = 11).
Metals, heavy Cadmium Copper Lead Nickel Ion exchange Spectrophotometry Chelation Resin Preconcentration

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

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

"Applications Of Ion-exchange Minicolumns In A Flow Injection System For The Spectrophotometric Determination Of Anions"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 233-244
Azad T. Faizullah and Alan Townshend

Abstract: The flow injection method is based on the displacement of SCN- bound to Dowex 1-X4 (200 mesh) by SO42-, Cl- and NO3-. The SCN- is treated with Fe(III) and the absorbance of the Fe - SCN- complex formed is measured at 465 nm. For the determination of NO3- in the presence of SO42- and Cl-, the SO42- and Cl- can be removed by use of a pre-column containing Dowex 50-X8 (Ag+ form) and a Jones zinc reductor (1.5 cm x 2 mm). Binary mixtures, e.g., Cl- and NO3-, can be analyzed by splitting the sample in the flow stream so that a part goes through the suppressor and another by-passes it to give a total response. The coefficient of variation for 0.11 mM NO3- is 1.5% (n = 5). The method is applied to the determination of NO3- in tap-water.
Nitrate Ion exchange Spectrophotometry Interferences Resin

"Flow Injection Potentiometric Stripping Analysis-a New Concept For Fast Trace Determinations"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 389-398
Wolfgang Frenzel and Peter Br&auml;tter

Abstract: The system described by Schulze and Frenzel (Mikrochim. Acta, 1984, I, 191) was used with four different flow-through cells. The carrier solution contained various amounts of Hg and the vitreous carbon was pre-coated with Hg. Up to four elements could be determined simultaneously at ppb to % levels. Rectilinear response was obtained for Pb and Cd in the range 5 to 100 µg l-1. The method was sucessfully applied to the determination of Zn, Pb and Cu in tap-water at levels down to 20 µg L-1 with 0.5 mL samples and to the direct determination of Pb and Cd in acid digests of biological samples.
Metals, heavy Zinc Lead Copper Cadmium Electrode Potentiometric stripping analysis Sample preparation Tecator

"Spectrophotometric Flow Injection Determination Of Nitrate Based On Reduction With Titanium(III) Chloride"
Anal. Chim. Acta 1986 Volume 186, Issue 1 Pages 289-294
A. Al-Wehaid and Alan Townshend

Abstract: The test solution (containing 0.02 to 5 µg mL-1 of N) is injected into a stream of water, which is then mixed with a stream of aqueous 6% TiCl3; the resulting NO2- then reacts in a stream of 0.6 M HCl containing 2% of sulfanilamide and 0.05% of N-1-naphthylethylenediamine dihydrochloride to form an azo-compound which is detected at 530 nm. Calibration graphs are rectilinear up to 5 µg mL-1 of N. The detection limit is 0.02 µg mL-1 of N. Interference from Cu(II) can be removed with use of Dowex 50W-X8 (H+ form) cation-exchange resin (other common ions do not interfere). The method is applied to potable water.
Nitrate Spectrophotometry Interferences

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

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

"Flow Cell With Flexible Deposition Efficiency For A Dual-detection System Based On Potentiometric Stripping Analysis And Atomic Absorption Spectrometry"
Anal. Chim. Acta 1987 Volume 196, Issue 1 Pages 153-161
G. Schulze, M. Koschany and O. Elscholz

Abstract: The cited flow cell is described in detail. The flow pattern, measurement of dispersion and deposition efficiency are discussed. Two types of dual detection are possible. If the sample concentration. is lower than the detection limit of flame AAS, a porous carbon felt electrode is inserted into the cell to collect the analyte ions for both potentiometric stripping analysis and pre-concentration. for AAS. If the concentration. of the sample is suitable for flame AAS, a vitreous-carbon electrode is used and two independent signals are obtained. The deposition efficiency can be altered from 1 or 2% (vitreous carbon) to 24% (carbon felt). In the determination of Pb in drinking water, pre-concentration. on carbon felt increased the sensitivity for flame AAS by one order of magnitude. This enabled determination of Pb in the µg L-1 range by flame AAS. A 1.5 mL injection required an electrolysis time of 60 s.
Lead Electrode Electrode Potentiometric stripping analysis Spectrophotometry Dispersion Flowcell Multidetection

"Flow Injection Analysis With A Coated Tubular Solid-state Copper(II)-selective Electrode"
Anal. Chim. Acta 1987 Volume 197, Issue 1 Pages 217-227
J. F. van Staden and C. C. P. Wagener

Abstract: The electrode (Ibid., 1986, 179, 407) was activated by the deposition of copper sulfide inside a copper tube by circulating (2 mL min-1) 0.1 ppm ammonium sulfide followed by 20 ppm ascorbic acid. The detector was used in a flow injection system and showed rectilinear response between 10 and 5000 µg mL-1 of Cu(II) and a detection limit of 0.5 µg mL-1. Detector performance was evaluated with respect to system parameters, pH and the influence of foreign ions; interference was caused by Cl- and Br-. However, the electrode could be used for determination of Cu(II) in the presence of <0.25 g L-1 of Cl- in waste water and tap-water.
Copper(II) Electrode Electrode Interferences

"Determination Of Paraquat By Flow Injection Spectrophotometry"
Anal. Chim. Acta 1987 Volume 199, Issue 1 Pages 203-208
E. Chico Guijarro, P. Y&aacute;&ntilde;ez-Sede&ntilde;o and L. M. Polo Di&eacute;z

Abstract: Paraquat was reduced with freshly prepared 1% Na2S2O4 solution in 0.1 M NaOH and determined by flow injection absorption spectrophotometry at 605 nm. Rectilinear calibration graphs were obtained for 0.1 to 1.0, 1.0 to 10 and 5.0 to 30.0 mg L-1 of paraquat under optimized conditions, the lowest limit being forty times less than that of the established spectrophotometric method. The flow injection method provided sample and reagent economy and higher sample throughput (80 h-1). The method was used to determine paraquat added to potable water and potatoes. After pre-concentration. by cation exchange on a Dowex 50W-X8 column, reproducible recoveries were obtained of 65 to 69 and 54 to 57%, respectively. Diquat interfered but could be removed previously by precipitation with NaOH. Interference by Ca(II) and Mg(II) was avoided by treating the sample with EDTA at pH 9 before introduction into the column. The determination of paraquat in different herbicide samples gave results in good agreement with those obtained by polarographic and manual spectrophotometric methods.
Paraquat Spectrophotometry Interferences Preconcentration

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

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

"Flow Potentiometric And Constant-current Stripping Analysis For Mercury(II) With Gold, Platinum And Carbon Fiber Working Electrode. Application To The Analysis Of Tap Water"
Anal. Chim. Acta 1987 Volume 201, Issue 1 Pages 1-9
Huang Huiliang, Daniel Jagner and Lars Renman

Abstract: Gold, platinum and carbon fibers with 10 µm diameter were mounted in PVC tubes and used as flow sensors in computerized potentiometric and constant-current stripping analysis for mercury, after electroplating ofa gold film onto the fiber surfaces. Compared to gold and glassy carbon disc electrodes, the fiber electrodes gare increased sensitivity and stability and were considerably simpler to handle. The gold-coated carbon fiber electrode gave a higher background than the gold fiber electrode, in both the potentiometric and constant-current stripping modes. Mercury(II) could be determined in presence of a 10^5-fold (molar) amount of copper(II) by constant-current stripping in media with chloride concentrations below 0.05 M. The detection limit for mercury(II) after 10 min of electrolysis was 45 ng L-1 at the 3s level.
Mercury(II) Amperometry Electrode Electrode Electrode Potentiometric stripping analysis

"Flow Injection Spectrophotometric Determination Of Aluminum Based On Chrome Azurol S And Cetylpyridinium Chloride"
Anal. Chim. Acta 1988 Volume 207, Issue 1-2 Pages 337-342
B. Bouzid and A. M. G. Macdonald

Abstract: A solution (120 µL) containing Al in HNO3 was injected into a carrier stream (2 mL min-1) comprising aqueous NH3 - hexamine buffer and aqueous 1,10-phenanthroline - hydroxylamine solution (pH ~5.7). The mixture was merged with a reagent stream (2 mL min-1) of 0.4 mM Chrome Azurol S (C. I. Mordant Blue 29), 8 mM hexadecylpyridinium chloride, buffer solution, ethanol and water and fed through a 2.25-m reaction coil. The absorbance was measured at 625 nm. Addition of 30% of ethanol to the reagent enhanced the absorbance of the ternary complex; the e value was 134,000. Calibration was rectilinear up to 400 ng mL-1 of Al. The determination limit was 5 ng mL-1 and the coefficient of variation was 0.5% for 0.1 µg mL-1 (n = 10). The method was applied in the determination of Al in potable waters.
Aluminum Spectrophotometry Complexation

"Determination Of Residual Chlorine In Tap Water By Flow Injection Spectrophotometry"
Anal. Chim. Acta 1988 Volume 208, Issue 1-2 Pages 317-320
Michio Zenki, Hirohisa Komatsubara and Kyoji T&ocirc;ei

Abstract: The sample (170 µL) was injected into water carrier (0.8 mL min-1) and mixed with the reagent (3 mg of thio-Michler`s ketone in 30 mL of 2-methoxyethanol, 3 mL of Triton X-100, 100 mL of 0.14 M dodecylbenzenesulfonate and 100 mL of 0.1 M formate buffer at pH 3.5). Absorbance was measured at 640 nm, and the calibration graph was rectilinear from 0.2 to 1.0 mg L-1 of Cl. Other ions present in tap water did not interfere.
Chlorine, residual Spectrophotometry Interferences Surfactant Triton X

"Preparation And Examination Of Calcium Ion-selective Electrodes For Flow Injection Analysis"
Anal. Chim. Acta 1988 Volume 211, Issue 1-2 Pages 213-221
Hiroko Wada, Tadao Ozawa and Genkichi Nakagawa, Yasukazu Asano and Satoshi Ito

Abstract: The electrodes are based on bis[bis(octylphenyl)phosphato]calcium(II), bis bis[4-(1,1,3,3-tetramethylbutyl)phenyl]phosphato calcium(II) (both Dorindo Laboratories, Japan) or Ionophore ETH 1001 (Fluka) [diethyl 4,5,NN'-tetramethyl-3,6-dioxo-octane-1,8-diamide-NN'-bis(undecyl-11-carboxylate)]. The response and lifetime of the electrodes and the interference effects of Mg and Na on the determination of 10 µM- to 1 mM Ca are examined. The ETH 1001 electrode is the most useful in flow injection analysis because it has the fastest and most stable response and the longest lifetime; as an example, Ca was determined in tap water.
Calcium Electrode Potentiometry Interferences

"Simultaneous Spectrophotometric Determination Of Calcium And Magnesium With Chlorphosphonazo-III By Flow Injection Analysis"
Anal. Chim. Acta 1988 Volume 212, Issue 1-2 Pages 291-295
Yuan Youxian

Abstract: To determine the total Ca plus Mg the sample (50 µL) was injected into a mixed stream of triethanolamine - HCl buffer solution (pH 7.0; 2.0 mL min-1) and aqueous 0.016% chlorphosphonazo III (I; 1.5 mL min-1). After reaction in a PTFE coil (80 cm x 0.8 mm), the absorbance of the solution was measured at 668 nm (e = 64,000 for Ca complex, 48,000 for Mg complex). Calibration graphs were rectilinear for up to 2 mg L-1 of Ca and Mg; the detection limit for each was 0.02 mg l-1. In determination of 2.0 mg L-1 each of Ca and Mg, the coefficient of variation were 3.7 and 3.2%, respectively (n = 12). To determine Ca alone the procedure was repeated at pH 2.2, adjusted with 1.6 mM HCl (e = 14,600 for Ca complex, 66 for Mg complex). The Mg was determined by subtraction. At both pH values Ba and Sr interfered. The method was applied to samples of tap- and seawater; results agreed with those obtained by AAS.
Calcium Magnesium Spectrophotometry Interferences Complexation Simultaneous analysis Method comparison

"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

"Lead Preconcentration With Flow Injection For Flame Atomic Absorption Spectrometry"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 329-337
S. R. Bysouth and J. F. Tyson, P. B. Stockwell

Abstract: Three flow injection manifolds were evaluated for the cited determination. The manifolds each involved a column containing, e.g., quinolin-8-ol material, an autosampler and an AAS detector. Elution was with HCl. Timed sample loading and matrix removal without passing the matrix to the nebulizer were achieved with one valve, but reagent consumption and calibration time were reduced by incorporating further valves. The effects of pH and interfering ions were studied. Water samples from lead pipes were analyzed by using a 2-valve manifold, a column packed with 2-methylquinolin-8-ol and direct neblization. Detection limits down to 1.4 ng mL-1 were achieved.
Lead Spectrophotometry 8-Hydroxyquinoline Calibration Column Interferences Preconcentration Valve Reagent consumption

"Utilization Of Kinetic-based Flow Injection Methods For The Determination Of Chlorine And Oxychlorine Species"
Anal. Chim. Acta 1989 Volume 224, Issue 2 Pages 383-391
G. Gordon, K. Yoshino, D. G. Themelis, D. Wood and G. E. Pacey

Abstract: The flow injection system was a Tecator 5020 analyzer. with a Tecator Chemifold II, and the detector was a Tecator 5024 FIAstar photometer with a 5024-011 optical unit and a 5032 controller. Samples were injected into water as carrier stream and mixed in a coil with 0.02 M or 12 M HCl, then this solution was mixed with 0.3 M KI reagent. The absorbance of the resulting I3- was measured at 370 nm in a 1-cm flow cell (volume 18 µL). With use of 0.02 M HCl, the signal is due to ClO2-, and with use of 12 M HCl it corresponds to ClO2- plus ClO3-, for solution free from ClO2 and/or Cl. By analysis at pH 8.3, ClO2 and free Cl can be determined without interference from the anions; oxalic acid can be used to mask Cl in the determination of ClO2 at pH 8.3. Conditions are given for determining each species without interference; calibration ranges were 0.2 to 10, 0.3 to 10, 0.08 to 5 and 0.08 to 5 mg L-1 for Cl, ClO2, ClO2- and ClO3-, respectively. The method is intended for application to drinking water.
Chlorine Chlorite Chlorate ion Chlorine dioxide Spectrophotometry Tecator Interferences Buffer Kinetic

"Determination Of Low Concentrations Of Chlorite And Chlorate Ions By Using A Flow Injection System"
Anal. Chim. Acta 1989 Volume 225, Issue 2 Pages 437-441
Demetrius G. Themelis, Delmer W. Wood and Gilbert Gordon

Abstract: Determination of ClO2- alone and in mixtures with ClO3- was achieved by reaction with I- at pH 2 to liberate I, which was measured spectrophotometrically at 370 nm. Both ClO2- and ClO3- react with I- in 6 M HCl, and the individual species were determined by multiple regression. The calibration graph was rectilinear from 2 to 150 µM-ClO2- and from 2 to 100 µM-ClO3-, with coefficient of variation of 0.4 and 1.2%, respectively. Detection limits were 0.04 mg L-1 for ClO2- and 0.03 mg L-1 for ClO3-. The method was fast and simple and suitable for sub mg L-1 levels in drinking water. Determination of ClO2- alone and in mixtures with ClO3- was achieved by reaction with I- at pH 2 to liberate I, which was measured spectrophotometrically at 370 nm. Both ClO2- and ClO3- react with I- in 6 M HCl, and the individual species were determined by multiple regression. The calibration graph was rectilinear from 2 to 150 µM-ClO2- and from 2 to 100 µM-ClO3-, with coefficient of variation of 0.4 and 1.2%, respectively. Detection limits were 0.04 mg L-1 for ClO2- and 0.03 mg L-1 for ClO3-. The method was fast and simple and suitable for sub mg L-1 levels in drinking water.
Chlorite Chlorate ion Spectrophotometry Calibration Detection limit

"Determination Of Nitrate By Flow Injection Analysis With An Online Anion-exchange Column"
Anal. Chim. Acta 1989 Volume 225, Issue 2 Pages 331-338
Surekha Devi and Alan Townshend

Abstract: Nitrate was determined by displacement of SCN- from an online anion-exchange mini-column and subsequent reaction with Fe(III) to give a red complex which was detected at 480 nm. Two suppressor columns were developed to remove anionic interference. A Pb2+-loaded ion-exchange column was used to allow determination of NO3- in the presence of SO42-, and a column loaded with Ag and Pb allowed determination of NO3- in the presence of SO42-, SO32- and Cl-. A copperized Cd reductor column was placed immediately after the suppressor column to trap eluted Ag and Pb ions which would otherwise depress NO3- response. The calibration graph was rectilinear for 50 to 600 µM-NO3-. The detection limit was 50 nM, and the coefficient of variation was 1%. The method was successfully applied to tap-water.
Nitrate Ion exchange Interferences Reduction column

"Off- And Online Determination Of Fluoride With Unsegmented Flow Configurations"
Anal. Chim. Acta 1990 Volume 230, Issue 1 Pages 137-143
Danhua Chen, M. D. Lique de Castro and Miguel Valc&aacute;rcel

Abstract: Several flow injection configurations were tested for the fluorimetric determination of F- as its ternary complex with Zr(IV) and calcein blue (I). In the preferred scheme, the aqueous carrier stream was merged with a stream (both 10 mL min-1) of 5 mM HCl that was 1 µM in the Zr(IV) - I complex, and was passed through a reaction coil before fluorimetric detection in a 25 µL flow cell at 410 nm (excitation at 350 nm). The calibration graph was rectilinear for 0.2 to 20 ng mL-1 of F- (injection volume 0.5 ml), the coefficient of variation (n = 7) at 5 ng mL-1 was 0.2%, and the sampling rate was 60 h-1. The method was applied to tap-water.
Fluoride Fluorescence Manifold comparison

"Fluorimetric Sensor For The Determination Of Fluoride At The Nanograms Per Millilitre Level"
Anal. Chim. Acta 1990 Volume 234, Issue 2 Pages 345-352
Danhua Chen, M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: Fluoride solution and 2 µM binary complex of Zr and Calcein Blue were injected simultaneously from double valves with a sample loop of 500 µL into a reactor (60 cm x 0.5 mm i.d.). The ternary complex formed was retained in the fluorescence flow cell (1.1 mm i.d.) of DEAE-Sephadex resin (40 to 120 µm) and the fluorescence was measured at 405 nm (excitation at 335 nm). After the maximum fluorescence had been obtained 0.4 M HCl was injected from a third valve to elute the complex and restore the baseline. The calibration graph was rectilinear from 1 to 40 ng mL-1 of F-; coefficient of variation was 1% (n = 7). The sample throughput was 30h-1. A comparison of the cited flow-through sensor with a probe sensor for the same chemical system showed the former to be superior. The method was applied in the analysis of potable water.
Fluoride Fluorescence Sensor Small sample Flowcell Calibration Method comparison Sephadex Resin Solid phase detection

"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

"Exchangeable Immobilized Enzyme Reactor For Enzyme Inhibition Tests In Flow Injection Analysis Using A Magnetic Device. Determination Of Pesticides In Drinking Water"
Anal. Chim. Acta 1990 Volume 234, Issue 1 Pages 113-117
Ralf Kindervater, Wolfgang K&uuml;nnecke and Rolf D. Schmid

Abstract: A flow injection analysis system is described for rapid automated enzyme inhibition testing. Sample in a carrier stream is mixed with a portion of enzyme immobilized on magnetic particles, and the amount of inactivated enzyme is determined. Exchange of used enzyme substrate is achieved with magnetic devices, which can be switched off to release bound material. The magnetic reactor is described and illustrated; its flow resistance is excellent. The system was applied in the determination of pesticides (carbofuran and malaoxon) in drinking water, with use of acetylcholinesterase, the activity of which was determined spectrophotometrically or electrochemically. The response was different for the two pesticides, but the limit of detection was 0.5 µg l-1. One analysis, including calibration, took 20 min.
Pesticides Immobilized enzyme Automation Enzyme Activity Detection limit Calibration

"Phosphorescence Detection In Flowing Systems: Selective Determination Of Aluminum By Flow Injection Liquid Room-temperature Phosphorimetry"
Anal. Chim. Acta 1990 Volume 234, Issue 1 Pages 233-238
Yi-Ming Liu, M. R. Fernandez de la Campa, M. E. Diaz Garcia and A. Sanz-Medel

Abstract: Aluminum was determined by micelle-stabilized phosphorimetry. A three-line flow injection manifold was used, involving 1 M acetate buffer (pH 5.5) containing Na2SO3 as carrier stream, 5 mM ferron in the buffer as chelating agent, and 0.2 M hexadecyltrimethylammonium bromide in the buffer as stabilizer. Phosphorescence was measured at 596 nm (excitation at 400 nm). The calibration graph was rectilinear for 4 µg mL-1. The coefficient of variation were 2.7% for 1 µg mL-1 (n = 10). The method was reasonably selective; >20 common species did not interfere or could be masked. The method was applied without sample pre-treatment to tap-water and dialysis fluid.
Aluminum Phosphorescence Selectivity Buffer Chelation Calibration Interferences Dialysis Micelle

"Automated Method For The Determination Of Boron In Water By Flow Injection Analysis With Inline Preconcentration And Spectrophotometric Detection"
Anal. Chim. Acta 1990 Volume 234, Issue 1 Pages 199-206
I. Sekerka and J. F. Lechner

Abstract: The system (schematically presented) involved pre-concentration. of B from a sample by ion-exchange on a column of Amberlite IRA-743, elution with a stream of azomethine-H in 2 M ammonium phosphate buffer (pH 6.6) containing EDTA, and detection of the B complex at 420 nm. Full operating details are given. Online pre-concentration. was carried out for 3 or 6 min for 10 or 10 µg L-1 of B, respectively. Recoveries were 96 to 101%. The coefficient of variation were 10% for 10 µg L-1 and 5% for 10 to 200 µg l-1. The detection limit was 1 µg l-1, with a sampling rate of 10 h-1. The method was applied to natural- and tap-water. Results show good agreement with those of ICP-AES. There was no interference, even for colored samples.
Boron Ion exchange Spectrophotometry Preconcentration Column Amberlite Buffer pH Detection limit Method comparison Interferences

"Online Determination Of Residual Aluminum In Potable And Treated Waters By Flow Injection Analysis"
Anal. Chim. Acta 1990 Volume 238, Issue 1 Pages 177-182
Richard L. Benson and Paul J. Worsfold, Frank W. Sweeting

Abstract: A portable, automated, flow injection based solid-state spectrophotometric field monitor is described. The Al was complexed with pyrocatechol violet to produce a colloidal lake which was measured at 580 nm. The interference from Fe(III) was masked by reduction to Fe(II) with hydroxylammonium chloride and complexation with 1,10-phenanthroline. The response was rectilinear up to 1000 µg L-1 and the limit of detection was 45 µg l-1. The coefficient of variation (n = 10) were 1.2 to 12.1% for 50 to 1000 µg L-1 and the reliability was >90% over 3 months. The monitor operates on a 30-min analytical cycle to give 48 results per day, and each cycle includes an autocalibration step. The performance conforms to industrial specifications.
Aluminum Spectrophotometry Complexation Interferences Portable

"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

"Flow Injection Determination Of Inorganic Forms Of Nitrogen By Gas Diffusion And Conductimetry"
Anal. Chim. Acta 1991 Volume 245, Issue 2 Pages 183-190
Lourival Cardoso de Faria and Celio Pasquini

Abstract: A flow injection conductimetric method was applied to the determination of ammonia, nitrate and nitrite at concentrations down to 5, 20 and 20 ng mL-1, respectively. Ammonia was determined by merging the injected sample with an alkaline solution (NaOH-EDTA) and passing the mixture through a diffusion cell. The ammonia released was collected by a flowing stream of deionized water that passed through a conductance flow cell. Nitrate and nitrite concentrations were determined after reduction to ammonia in alkaline medium using a column filled with metallic zinc. The ammonia produced was then measured as described above. About 60 samples per hour can be processed with a relative standard deviation of about 1%. Satisfactory agreement was observed between results for ammonia in samples of natural water and nitrate in tap and mineral water determined by the proposed method and by standard spectrophotometric procedures. Speciation can be achieved by adding sulfanilic acid to remove nitrite from the sample and determining the ammonia without the use of the column.
Ammonium Nitrate Nitrite Conductometry Gas diffusion Speciation

"Flow Injection Determination Of Zinc By Fluorescence Spectrometry"
Anal. Chim. Acta 1991 Volume 255, Issue 2 Pages 325-328
R. Compa&ntilde;&oacute;, S. Hern&aacute;ndez-Cassou and M. D. Prat*, L. Garc&iacute;a-Beltr&aacute;n

Abstract: A flow injection manifold is illustrated in which a stream of succinate buffer solution (pH 6.1) containing masking agents, 0.1 M Na2S2O3 and/or Na pyrophosphate, was merged with a stream of Brij-35 surfactant (both at 5 mL min-1) in a 60-cm coil, before mixing with the sample stream (58 µL). The mixture was reacted with 1 mM 5,7-dichloro-2-methylquinolin-8-ol in aqueous 40% ethanol (1 mL-1) in a 30-cm coil, before fluorimetric detection at 534 nm (excitation at 397 nm). The calibration graph was rectilinear from 10 to 600 µg L-1 of Zn, with a detection limit of 3 µg l-1. The coefficient of variation (n = 15) was 1.8% for 200 µg Zn. Tolerance limits for interfering ions are tabulated; sampling time was 180 h-1. The method was applied to potable water and pharmaceutical preparations and results were in good agreement with those obtained by AAS and the values stated by manufacturers, respectively. The masking agent was more efficient in this flow injection system than one in which the reagent stream was mixed with the buffer and surfactant streams before mixing with the sample stream.
Zinc Fluorescence Buffer Interferences Surfactant

"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 Spectrofluorimetric Method To Determine Aluminum(III) In Water"
Anal. Chim. Acta 1992 Volume 262, Issue 1 Pages 91-96
Francisco Carrillo, Concepci&oacute;n P&eacute;rez and C&aacute;rmen C&aacute;mara*

Abstract: The proposed method is based on the use of Eriochrome red B (C. I. Mordant Red 7; I) and does not require extraction of the fluorescent complex. The flow injection system (described) was optimized for the effects of pH (6.0), buffer (hexamine or Na acetate), I concentration. (0.025%), reactor coil parameters, flow rate (1 mL min-1) and injection volume (0.1 ml). The carrier was 0.01 M 1,10-phenanthroline - 0.5 M hydroxylammonium chloride, and fluorescence measurements were made with excitation and emission at 525 and 595 nm, respectively. Results were obtained from calibration graphs, which were rectilinear up to 1 µg mL-1 of Al(III) for both buffers; the limits of detection were 0.35 and 0.4 ng mL-1 for the acetate and hexamine buffers, respectively. Selectivity and precision were also excellent and better than obtained by graphite-furnace AAS or other methods. The method was successfully applied to the determination of Al in tap- and mineral waters. A room-temp. flow injection spectrofluorimetric method is presented to determine Al(III), based on the use of Eriochrome Red B in the presence of H2MTA+-HMTA (HMTA = hexamethylenetetramine) or HOAc-OAc- buffer. Various chemical and phys. variables affecting the reaction in the flow system were evaluated. The proposed method is very sensitive, with a detection limit of 0.3 ng/mL and a precision at the 20 ng/mL level of 2.5%. The calibration range is linear 1 µg/mL. The method was successfully applied for determination of Al(III) in tap and mineral waters.
Aluminum(III) Fluorescence Optimization pH Buffer Sensitivity

"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

"Flow Injection Spectrophotometric Determination Of Propoxur With P-aminophenol"
Anal. Chim. Acta 1992 Volume 266, Issue 1 Pages 119-126
Karim D. Khalaf, J. Sancen&oacute;n and M. de la Guardia

Abstract: The sample solution was injected into a stream (2.2 mL min-1) of water, which was merged with 0.33 M NaOH (2.2 mL min-1) and mixed in a 2-m coil. The resulting stream, containing the hydrolysis product of propoxur (2-isopropoxyphenol, as the Na salt), was mixed (in a 7-m coil) with a stream containing the quinonimine produced by oxidation via mixing of 9 mM 4-aminophenol and 0.02 M KIO4 (each flowing at 2.2 mL min-1) in a 1-m coil. The optimum reaction temperature was 25°C, and the absorbance of the indo dye produced was measured at 600 nm. The calibration graph was rectilinear for up to 16 µg mL-1 of propoxur, and the detection limit was 0.1 µg mL-1. The coefficient of variation (n = 5) was 0.1% for 38 µM. Recoveries ranged from 94.0 to 98.3%. The method was applied to natural and tap-water. The spectrophotometric determination of propoxur [2-(1-methylethoxy)phenyl Me carbamate] was carried out with p-aminophenol (PAP) in a flow system. The method involves the online hydrolysis with NaOH of propoxur to 2-isopropoxyphenol and the oxidation of PAP to its reactive quinoneimine with KIO4 and the reaction between the phenolate and the quinoneimine. A 4-channel flow manifold was employed to carry out all the different steps of the reaction considered, monitoring the indo dye formed at 600 nm. The developed procedure provides a typical calibration line of A = -0.0007 + 1.8 x 103C (A = absorbance; C = concentration. in M) with a regression coefficient of 0.9998 and a limit of detection, for a probability level of 95% (for K = 3) of 0.1 µg mL-1. In the anal. of synthetic samples containing propoxur and 2-isopropoxyphenol, the total concentration. of propoxur was determined with a recovery from 94% to 98.3%. The method provides results comparable to those obtained by the batch anal. of natural water samples spiked with propoxur.
Propoxur Spectrophotometry Optimization

"Segmental Flow Injection With Ion-selective Electrodes For The Determination Of Fluoride In Water"
Anal. Chim. Acta 1993 Volume 274, Issue 1 Pages 125-128
J. A. Borzitsky and A. V. Dvinin, O. M. Petrukhin* and Yu. I. Urusov

Abstract: The design and operation of a flow analyzer. with enhanced sampling frequency, which combined the features of flow injection and continuous-flow analysis, is described. Parameters were optimized to ensure the highest rate of analysis allowed by the bubble-through flow cell, which was equipped with fluoride-selective electrodes. Fluoride was determined in drinking water samples (0.1 ml) with a sampling frequency as high as 720 h-1 and a relative standard deviation of 1%; calibration graphs were rectilinear in the range 20 to 80 µM-fluoride.
Fluoride Electrode Segmented flow Optimization

"Simple And Rapid Flow Injection Spectrophotometric Determination Of Carbaryl After Liquid-liquid Extraction"
Anal. Chim. Acta 1993 Volume 280, Issue 2 Pages 231-238
Karim D. Khalaf, A. Morales-Rubio and M. de la Guardia

Abstract: Carbaryl (I) and its hydrolysis product 1-naphthol (II) were extracted from real irrigation, tap and well water samples with xylene, and then back-extracted into 0.2 M NaOH. Portions (600 µL) of the aqueous layer were analyzed by flow injection spectrophotometry (diagram given). Standards were injected into a stream (4 ml/min) of 0.2 M NaOH and carried to a reaction coil (75 cm x 0.8 mm i.d.) where alkaline hydrolysis of I to II occurred. This was not necessary for pre-treated samples, which were merged directly with mixed streams (4 ml/min) of p-aminophenol (50 µg/ml) and 4 mM KIO4 which had passed through a reactor coil (45 cm x 0.8 mm i.d.) to produce the quinoneimine form of p-aminophenol. The quinoneimine then reacted with II in a reaction coil (6 m x 0.8 mm i.d.) to produce an indophenol dye which was detected 596 nm. The calibration graphs were linear from 1.2-6 µg/ml of I and 2-8 µg/ml of II with corresponding detection limits of 26.5 and 11.8 ng/ml; the RSD were 0.14% and 0.3%, respectively. 2-naphthol did not interfere. Recoveries from spiked samples were 95-102%. Up to 110 samples/h could be analyzed.
Carbaryl Spectrophotometry Sample preparation Solvent extraction Interferences

"Automatic Continuous-flow Determination Of Paraquat At The Sub-nanogram Per Millilitre Level"
Anal. Chim. Acta 1993 Volume 281, Issue 1 Pages 103-109
Manuel Agudo, Angel R&iacute;os and Miguel Valc&aacute;rcel*

Abstract: A water sample (I 0.05 M in NaNO3) pumped at 4 ml/min was mixed with 1% dithionite reagent of pH 12.5 pumped at 2.5 ml/min in a 30 cm-long coil and the mixture was passed to a flow cell containing Dowex 50W-X8-200 (ammonium form). The blue complex bound to the resin was monitored at 605 nm, then the sample stream was changed to an elution solution of ammonium chloride using a switching valve. The calibration graphs depended on the sample volume used; 1 mL gave a linear graph up to 0.2 µg/ml of paraquat with an RSD of 4.6% at a sampling frequency of 10/h, whereas 250 mL gave a linear graph from 0.4-5.5 ng/ml with an RSD of 7.9% and a sampling frequency of 0.9/h. At a volume of 250 mL the detection limit was 0.11 ng/ml. Interference studies showed that other pesticides were tolerated at a ratio of 100:1 except for diquat where this value was 10:1. The method was applied to the determination of paraquat in natural and tap waters and in studies of the adsorption of the herbicide by different soils.
Paraquat Dowex Resin Interferences

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

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

"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

"Off-line And Online Preconcentration Of Trace Levels Of Beryllium Using Complexing Agents With Atomic-spectrometric And Fluorimetric Detection"
Anal. Chim. Acta 1993 Volume 283, Issue 2 Pages 909-915
D. B. Do Nascimento and G. Schwedt

Abstract: Two methods were investigated. The first method used polyethylene powder as an adsorbent for the pre-concentration of the stable complex formed between Be and Chrome azural S (CAS; C. I. Mordant Blue 29) followed by analysis by graphite-furnace AAS (GF-AAS). The sample solution was adjusted to pH 3 with HCl and treated with 0.5 M succinic acid buffer solution of pH 4.5 and 6% aqueous CAS. The mixture was passed (0.5 ml/min) through the pre-concentration column containing polyethylene powder. After washing the column with water and drying in air, the Be-CAS complex was eluted with ethanol (0.4 ml/min). The eluate were analyzed by GF-AAS at 239.4 nm, with Ar purge gas (temp. programming details given). The method was used to determine Be in tap water. The detection limit was 0.8 µg/l of Be and the RSD were 2.5-4.1%. Recoveries were 92-104%. The second method (details given) used an ion-exchange micro-column in a FIA system for the pre-concentration of Be, which was reacted with morin and detected by fluorescence. The method was also used to determine Be in tap water. The detection limit was 0.2 µg/l of Be and the RSD was ~1.5%. Recoveries were 95-105%.
Beryllium Ion exchange Fluorescence Spectrophotometry Column Preconcentration Method comparison

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

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

"Ion-chromatographic Separation And Online Cold Vapor Atomic Absorption-spectrometric Determination Of Methylmercury, Ethylmercury And Inorganic Mercury"
Anal. Chim. Acta 1994 Volume 284, Issue 3 Pages 661-667
Corrado Sarzanini*, Giovanni Sacchero, Maurizio Aceto, Ornella Abollino and Edoardo Mentasti

Abstract: The ion chromatographic separation of methylmercury, ethylmercury and inorganic mercury as cysteine complexes was investigated. The chromatographic apparatus was interfaced with cold vapor atomic absorption spectrometry for detection using an on-line continuous flow cell coupled with a reduction system (sodium tetrahydroborate). The influence of the composition of the eluent (pH, ionic strength, cysteine concentration) and stripping gas flow-rate was investigated. The method was optimized by coupling an on-line pre-concentration step. The detection limits, evaluated on 100.0 mL samples, were 2, 10 and 4 ng for Hg, CH3Hg and C2H5Hg, respectively. The method was applied to synthetic mixtures and natural samples (tap water) and furnished satisfactory results.
Mercury(II) Methylmercury ion Ethylmercury HPIC Spectrophotometry Speciation Optimization Preconcentration

"Method Comparison For The Determination Of Labile Aluminum Species In Natural Waters"
Anal. Chim. Acta 1994 Volume 286, Issue 3 Pages 401-409
Ben Fairman and Alfredo Sanz-Medel*, Mercedes Gallego and Maria Jos&eacute; Quintela, Phil Jones and Richard Benson

Abstract: The results of an inter-laboratory project for the determination of labile monomeric Al in lake and tap water are presented. A modified Driscoll-pyrocatechol violet (PCV) fractionation method (cf. Fairman and Sanz-Medel, Int. J. Environ. Anal. Chem., 1993, 50, 161), with a 10 min reaction time, 3.5 mL samples, a 1 mL column of Amberlite IR-120 conditioned from the Na+ form and split calibration was used as a reference method; each laboratory also used an alternative method (FIA 8-hydroxyquinoline-5-sulfonic acid, LC and FIA Driscoll-PVC methods; details given). High-density polyethylene containers were suitable for sample storage after leaching with 10% HNO3 for 48 h and samples were stable for 30 days. The value of a quality control program whereby solution containing 11 and 55 µg/l of Al in 0.01 M HNO3 are analyzed (preferably by electrothermal-AAS) periodically over the test period was demonstrated. Samples containing 100-200 µg/l of Al gave the best speciation results. The Driscoll-PCV method was fully portable and gave RSD of 15% for toxic labile monomeric Al in the more stable samples.
Aluminum LC Spectrophotometry 8-hydroxyquinoline-5-sulfonic acid Amberlite Speciation

"Flow Injection Extraction Without Phase Separation Based On Dual-wavelength Spectrophotometry"
Anal. Chim. Acta 1994 Volume 288, Issue 3 Pages 237-245
Hanghui Liu and Purnendu K. Dasgupta*

Abstract: A flow injection extraction (FIE) system is described. The absorbance was measured radially on the same PTFE tube that formed the extraction coil. The detector used a LED-based dual-wavelength photometric system with PC-based data acquisition and processing. One non-specific wavelength was used to recognize the phases and the other to monitor the analyte. The FIE system was used to determine anionic surfactants (AS) by ion-pairing with methylene blue (MB) and extraction into CHCl3. A water carrier stream (0.45 ml/min) was merged with the MB reagent stream (0.06 mg/ml; 0.16 ml/min). After passing through a mixing coil (15 cm x 0.17 mm i.d.), the stream passed to the segmenter. A CHCl3 stream (0.05 ml/min) was pumped to the segmenter and alternate segments of aqueous and organic phase were pumped to the extraction/detection coil (2.8 m x 0.38 mm i.d.). The MB-AS ion-pair was determined at 660 nm with identification at 850 nm. The calibration graph was linear up to 2.5 ppm of C-12 alkylbenzene sulfonate with a detection limit of 0.025 ppm and an RSD of 1.5%. The method was applied to tap- and lake-water. Recoveries were >94.4%.
Surfactants, anionic Spectrophotometry Sample preparation Light emitting diode Computer Extraction

"Stopped-flow Injection Kinetic Determination Of Multicomponent Samples: Simultaneous Determination Of Mercury(II) And Silver(I)"
Anal. Chim. Acta 1994 Volume 294, Issue 2 Pages 195-199
Jianhua Wang* and Ronghuan He

Abstract: The simultaneous determination of Hg(II) and Ag(I) was based on their catalytic effect on the ligand substitution reaction between hexacyanoferrate(II) and α,α'-bipyridyl. The flow injection manifold allowed streams of 6 mM thiourea (pH 3.2, 2 ml/min), 0.75 mM bipyridyl (2 ml/min), 0.5 mM [Fe(CN)6]4- (2 ml/min) and acetate buffer solution (pH 3.2, 2.4 ml/min) to be merged. The merged streams were passed through a reaction coil (200 x 0.5 mm i.d.) and a detector cell, both maintained at 90°C. Flow was stopped for 200 s and the absorbance was measured at 536 nm at 100 s and 200 s after injection of the sample. The sample solution was injected into the [Fe(CN)6]4- stream via a 30 µL sample loop. The calibration graphs were linear for 0-75 ng/ml Hg(II) and 0-64 ng/ml Ag(I) and the detection limits were 0.5 ng/ml Hg(II) and 1 ng/ml Ag(I). Most common ions did not interfere with the determination except for Fe3+, Co2+ and Zn2+. The method was applied to the analysis of tap water, waste water and a synthetic sample. The RSD (n = 6) for 0.263-38.85 ng/ml Hg(II) and 0.41-47.8 ng/ml Ag(I) were 3.52-5.20 and 3.20-4.89%, respectively.
Mercury(II) Silver(I) Spectrophotometry Interferences Kinetic Stopped-flow

"Characterization Of Inhibitors Of Acetylcholinesterase By An Automated Amperometric Flow Injection System"
Anal. Chim. Acta 1995 Volume 300, Issue 1-3 Pages 117-125
Alexander G&uuml;nther* and Ursula Bilitewski

Abstract: Acetylcholinesterase was immobilized on amino-terminated magnetic particles and a suspension was pumped into a magnetic reactor of a flow injection manifold. The system was used for enzyme inhibition tests, with a carrier stream of 0.01 M phosphate buffer of pH 8 flowing at 1 ml/min and acetylthiocholine chloride as enzyme substrate. Inhibition constants were obtained for the insecticides carbofuran, paraoxon-ethyl and -methyl and malaoxon and the enzyme activity was determined amperometrically by the oxidation of thiocholine at screen-printed Pt electrodes at a potential of 600 mV. The experimental detection limits were 3-7 µg/l, which agreed with those calculated from the inhibition constants. The results were comparable with those obtained photometrically by the reaction of thiocholine with Ellman's reagent (5,5'-dithiobis-2-nitrobenzoic acid) in the same FIA system. The method was applied to the analysis of insecticides in natural and drinking waters.
Insecticides Carbofuran Malaoxon Paraoxon Amperometry Electrode Immobilized enzyme Magnetic particles

"A Flow Injection Type Chemiluminescence-based Sensor For Cyanide"
Anal. Chim. Acta 1995 Volume 304, Issue 3 Pages 369-373
Jianzhong Lu, Wei Qin, Zhujun Zhang*, Manliang Feng and Yanjun Wang

Abstract: The FIA system for the determination of cyanide consisted of a reaction column (6 cm x 4 mm i.d.), a coiled flow cell (100 x 0.5 mm i.d.) and a photomultiplier tube. The reaction column was packed with 0.2 g of a 1:1 mixture of luminol immobilized on Amberlyst A-27 (0.4 mmol/g of resin) and Cu2+ immobilized on D151 ion-exchange resin (8 mmol/g of resin). Luminol and Cu2+ were released from the reaction column by injecting 100 µL 4 mM NaCl into the water carrier stream. This stream was merged with the sample stream and a 0.1 M NaOH stream. The flow was passed to the flow cell where the chemiluminescence was detected. Flow rates were 2 ml/min. The calibration graph for cyanide was linear for 5 ng/ml to 2 µg/ml and the detection limit was 2 ng/ml. The method was applied to the analysis of tap and waste water following isolation of cyanide by distillation. A suitable volume of sample solution was mixed with 10 mL of 10% zinc nitrate and 2 drops of methyl orange indicator and adjusted to orange with 15% tartaric acid. The solution was diluted to 250 mL and distilled. The distillate was collected in 10 mL of 2% NaOH. After about 90 mL of distillate was collected, the pH was adjusted to 6 and the solution was diluted to 100 mL for analysis. Recoveries of 1.5-15.5 µg/l cyanide from tap and waste water were >95%.
Cyanide Chemiluminescence Sensor Immobilized enzyme Immobilized reagent

"A Mechanized System For The Determination Of Low Levels Of Quickly Reacting Aluminium In Natural Waters"
Anal. Chim. Acta 1995 Volume 306, Issue 2-3 Pages 173-181
Lars-G&ouml;ran Danielsson and Anders Spar&eacute;n*

Abstract: A continuous flow system has been connected to a graphite furnace atomic absorption spectrometer. The system is used to determine low levels of 'quickly reacting Al' (Alqr) in natural waters. In the flow system, aluminium reacts with oxine for 2.3 s and the formed complex is then extracted into toluene. Iron interference is minimized with a masking buffer present in the reagent. Via a simple interface, the toluene extract is introduced into the graphite tube. Good repeatabilities (RSD ~2%, n = 10) were obtained, both for standard solutions and for natural waters. The detection limit is < 0.5 g l-1, and the sample throughput using 3 injections/sample, is ~10 samples h-1. The system has been used for determining Alqr in tap water, and is well suited for aluminium fractionation in near-neutral waters.
Aluminum, reactive Spectrophotometry Speciation Solvent extraction Organic phase detection Complexation Masking agent Buffer

"Determination Of Metal Ion Mixtures Using PH Gradient Flow Injection Analysis With Fluorescence Detection"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 313-328
N. Porter*, B. T. Hart, R. Morrison and I. C. Hamilton

Abstract: A pH gradient flow injection system with fluorimetric detection was described for the analysis of ternary and quaternary mixtures of Zn, Cd, Pb, Mg and Al. The pH gradient was formed by injecting a basic buffer solution into an acidic buffer stream. Four different buffer systems were used. For each system the pH variable buffer stream was merged with 0.1 mM 8-hydroxyquinoline-5-sulfonic acid and sample streams. The flow then passed through a knotted PTFE mixing coil (30 cm x 0.5 mm id.) and a column (18 cm x 2.5 mm i.d.) containing 0.25 mm glass beads to the detection cell (90 µL) where the metal chelates were monitored at 520 nm (excitation at 369 nm). All measurements were carried out in triplicate with each run taking 60 s. The fluorescence-time scans were analyzed by a partial least squares algorithm. The dynamic range of the method was 0.1-10 µM for Zn, Cd, Al and Mg. The method was used to analyze tap water. The results were comparable to those obtained by AAS.
Aluminum Cadmium Lead Magnesium Zinc Fluorescence pH gradient Method comparison Glass beads Chelation 8-hydroxyquinoline-5-sulfonic acid Knotted reactor Partial least squares

"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

"Preconcentration And Flow Injection Multivariate Determination Of Priority Pollutant Chlorophenols"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 238-245
F. Navarro-Villoslada, L. V. P&eacute;rez-Arribas, M. E. Le&oacute;n-Gonz&aacute;lez* and L. M. Polo-D&iacute;ez

Abstract: Water (500 ml) containing up to 200 ppb of chlorophenols was acidified with 10 mL 3 M HCl and passed through a XAD-4 column (1.2 g of resin; 65 mm x 5 mm i.d.) at 4 ml/min. The chlorophenols were eluted with 10 mL methanol. The eluate was evaporated to dryness and the residue was dissolved in 10 mL 0.01 M borate buffer of pH 9.1. A 250 µL portion of the solution was injected into a borate buffer carrier stream (1.5 ml/min) and merged with a 1.5 g/l tetrabutylammonium nitrate stream (1.2 ml/min). The flow passed through a reaction coil (30 cm x 0.3 mm i.d.) to allow chlorophenol-tetrabutylammonium ion-pairs to form. The ion-pairs were extracted into CHCl3 by merging with a CHCl3 stream (0.6 ml/min). After passing through the extraction coil (130 cm x 0.3 mm i.d.) the phases were separated in a membrane phase separator. The spectra of the organic phase were recorded every 0.6 s from 200-430 nm. The first derivative spectra was calculated. Calibration standards contained up to 10 mg/l of chlorophenols. Three multivariate methods were used, namely, classical least squares, partial least squares and a Kalman filter. The method was used to analyze tap water spiked with chlorophenols up to 180 µg/l. All three multivariate calibration methods gave acceptable errors (~e;5%) for each chlorophenol (listed) except 2,4,6-trichlorophenol (~e;15%).
Phenols, chloro Spectrophotometry Spectroscopy Sample preparation Calibration Ion pair extraction Kalman filter Organic phase detection Preconcentration Multivariate calibration Partial least squares Phase separator

"Online Determination Of Vanadium By Adsorptive Stripping Voltammetry"
Anal. Chim. Acta 1995 Volume 312, Issue 1 Pages 15-25
Gillian M. Greenwaya,* and Georg Wolfbauerb

Abstract: A FIA method was developed based on the adsorption of a V-cupferron complex onto a mercury film electrode followed by cathodic stripping. The wall jet detection cell was fitted with a glassy carbon working electrode, a Ag/AgCl (3 M KCl) reference electrode and a stainless steel counter electrode. The Hg film was deposited in situ (details given) The water carrier stream was switch to the ligand stream containing 20 µM-cupferron and 0.05 M KBrO3 in 0.1 mM acetate buffer at pH 4.6 for the determination of V. Analyte solution was injected into the ligand stream and a deposition potential of +200 mV was applied to the working electrode. After 90 s the voltammogram was recorded in the differential pulse mode with a scan rate of 10 mV/s, a pulse amplitude of 50 mV and an end potential of +50 mV. All flow rates were 0.2 ml/min. The calibration graph was linear up to 3.5 µg/l of V with a detection limit of 8 ng/l. The RSD (n = 10) were 3.5%. The method was applied to the determination of V in tap water. To determine V in matrices which contain a high salt concentration, such as seawater, the measurements were carried out by anodic stripping. A deposition potential of 0 V was applied for 100 s and then the potential was scanned to +150 mV. The RSD for the determination of 1.3 µg/l V in seawater was 7% using a standard additions calibration procedure.
Vanadium Electrode Voltammetry Standard additions calibration

"Differential Flow Injection Potentiometry With Double Sensitivity Using One Ion-selective Membrane"
Anal. Chim. Acta 1995 Volume 313, Issue 1-2 Pages 83-87
Frank Zuther*, Bernd Ross and Karl Cammann

Abstract: Nitrate was determined by differential flow injection potentiometry using a symmetrical flow-through cell equipped with one ion-selective membrane and two Ag/AgCl reference electrodes, one positioned on each side of the membrane. The two sides of the detection cell were connected by a PTFE tube (0.8 mm i.d.) which allowed the sample to come into contact with both sides of the membrane. Separate or overlapping peaks could be obtained by varying the length of the connecting tube. The ion-selective membrane (10 x 5 mm) consisted of tetradodecylammonium bromide, potassium tetrakis(4-chlorophenyl)borate and 2-nitrophenyloctyl ether in a PVC matrix. The carrier solution (3 ml/min) was 1 mM Li2SO4. The calibration graph for up to 10 mM nitrate showed a sensitivity of 115.2±1.2 mV/decade when using a connecting tube volume of 2 mL and an injection volume of 1 mL. A sensitivity of 110.5±0.8 mV/decade was obtained for the same calibration range with a connecting tube volume of 0.25 mL and an injection volume of 0.5 mL. A detection limit of 0.6 µM-nitrate was achieved with a connecting tube volume of 0.5 mL and an injection volume of 0.5 mL. The method was applied to the determination of nitrate in tap water and spinach and the results were confirmed by ion chromatography.
Nitrate Potentiometry Electrode Membrane

"Graphite-poly(tetrafluoriethylene) Electrodes As Electrochemical Detectors In Flowing Systems"
Anal. Chim. Acta 1995 Volume 314, Issue 1-2 Pages 13-22
C. Fern&aacute;ndez, A. J. Reviejo and J. M. Pingarr&oacute;n*

Abstract: Graphite/PTFE composite electrodes (details given) were used as indicator electrodes for the flow injection amperometric detection of the herbicides, thiram (I) and disulfiram (II) at a potential of +1 V vs. Ag/AgCl/3 M KCl in a carrier stream (1.9 ml/min) of 0.1 M phosphate buffer at pH 7.4 and with an injection volume of 250 µL. Calibration graphs were linear up to 40 µM-I and -II and the detection limits were 0.043 and 0.02 µM, respectively. RSD (n = 10) were 7.7 and 5.7%, respectively, for 0.1 µM of I and II. Recoveries of 40 µg/l of I from spiked tap and well water were >97%. The adsorptive pre-concentration of the herbicides from flowing streams (2.7 ml/min) was carried out at 0.0 V. At the end of the pre-concentration period the phosphate buffer stream was passed for 30 s prior to the determination of the suface-bound herbicide by applying a linear sweep anodic potential ramp up to +1.2 V. Calibration graphs were linear from 0.4-1 and 0.2-1 µM-I and -II, respectively. The continuous-flow injection separation of I and II was carried out by inserting a 30-40 µm VYDAC SC-201 column (3 cm x 0.2 mm i.d.) into the FIA system and using acetonitrile/0.1 M phosphate buffer at pH 7.4 (1:3) as mobile phase (1.9 ml/min).
Disulfiram Thiram Amperometry Electrode Preconcentration Column

"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

"Novel Potentiometric Monitoring Combined With Coulometric Reagent Generation"
Anal. Chim. Acta 1996 Volume 319, Issue 1-2 Pages 49-58
G&eacute;za Nagy, Kl&aacute;ra T&oacute;th*, Zs&oacute;fia Feh&eacute;r and Jen Kunovits

Abstract: A potentiometric flow-through monitor was developed in which different amounts of standard or reagent were added to the sample stream by current-programmed coulometry. The monitor was utilized to monitor the concentration of chloride in tap water over an 8 h period. The tap water stream (5.51 x 10^-5 L/s) was merged with a Ag+ ion reagent stream (5.51 x 10^-5 L/s) in 0.1 M KNO3/5 mM HNO3 produced coulometrically at 3.5 mA (~e;30 mV) at a Ag electrode with a Pt wire counter electrode. The flow then passed through the potentiometric detection cell which was equipped with a chloride ISE as the indicator electrode and a double junction calomel reference electrode. A computer was used for data acquisition, for electrical noise rejection, for signal recognition and for calculating the analytical results. Over an 8 h period the concentration of chloride in tap water was found to fluctuate between 0.45-0.70 mmol/L using a measurement cycle of 400 s.
Chloride Potentiometry Electrode

"Multicomponent Flow Injection Based Analysis With Diode-array Detection And Partial-least-squares Multivariate Calibration Evaluation. Rapid Determination Of Calcium(II) And Magnesium(II) In Waters And Dialysis Liquids"
Anal. Chim. Acta 1996 Volume 320, Issue 2-3 Pages 177-183
O. Hern&aacute;ndez, F. Jim&eacute;nez, A. I. Jim&eacute;nez, J. J. Arias,* and J. Havel

Abstract: The FIA manifold comprised 0.5 mm i.d. PTFE capillaries, a 4-way injection valve and a peristaltic pump. Samples were injected in to 2 mM 4-(2-pyridylazo)-resorcinol in 0.1 M Tris buffer of pH 9.6 (2 ml/min) and after passage through a reaction coil (80 cm) spectra were recorded on a diode array spectrophotometer every 1s. A partial least squares method was used for calibration (details given). The system was used to determine Ca and Mg in potable waters and dialysis liquids and in mixtures of Ca, Mg and Cu. Satisfactory results were obtained with a scanning time equivalent to 21 s and wavelengths of 510 nm to 552 nm. Sample throughput was 30 per hour.
Calcium(2+) Magnesium(II) Spectrophotometry Partial least squares Buffer Multicomponent Dialysis Multivariate calibration

"Determination Of Calcium In Water, Urine And Pharmaceutical Samples By Sequential Injection Analysis"
Anal. Chim. Acta 1996 Volume 323, Issue 1-3 Pages 75-85
J. F. van Staden* and R. E. Taljaard

Abstract: The sequential injection analysis is based on the fast complexation reaction between metalphthalein and Ca2+ followed by spectrophotometric detection at 573 nm. Plugs of 0.31 mL of water, 0.47 mL of 14% 2-amino-2-methylpropanol-1-ol buffer solution of pH 10.5, 0.23 mL of 0.0025% metalphthalein solution of pH 1.9 and 0.23 mL of sample were drawn at 4.68 ml/min into a holding coil (50 cm x 1.6 mm i.d.). The flow was then reversed and the stacked plugs were propelled through reaction coils (90 cm x 1.1 mm i.d. and 115 cm x 0.6 mm i.d.) to the flow-though detection cell (80 µL) where the absorbance was measured. A linear response was obtained for up to 20 mg/l of Ca and the detection limit was 0.05 mg/l. The RSD (n = 10) for 1-20 mg/l Ca were 0.66-0.85%. The method was applied to the determination of Ca in an effervescent tablet, tap water and urine, and the results were validated by AAS. The sampling frequency was 43 per h.
Calcium Spectrophotometry Sequential injection

"A Liquid Drop: A Windowless Optical Cell And A Reactor Without Walls For Flow Injection Analysis"
Anal. Chim. Acta 1996 Volume 326, Issue 1-3 Pages 13-22
Hanghui Liu and Purnendu K. Dasgupta*

Abstract: A dynamically growing and falling liquid drop was proposed as a windowless optical detection cell for FIA. The drop of ~e;52 µL was formed on the end of a PTFE tube (3.7 mm o.d, 1.5 mm i.d.). Detection was performed using a blue light-emitting diode (450 nm) and the transmitted light was conducted by a 1.5 mm o.d. plastic optical fiber to a photodiode equipped with an interference filter centred at 460 nm. The system was evaluated by determining sulfate using the Ba2+ precipitation reaction by injection of ~e;70 µL of test solution into a reagent stream (0.8 ml/min) of 5% BaCl2 in 0.01 M HCl. The FIA peak was observed over several drops. Quantitative measurements were made at a single drop and calibration ranges were linear for 20-2000 mg/l at drops 3 and 5 and 20-1000 mg/l at drop 4. The detection limit was 26 mg/l and the RSD (n = 8) for 100 mg/l of sulfate was 4%. The method was used to determine sulfate in tap water and the results were confirmed by ion chromatography. The liquid drop could also serve as a reactor cell by mixing the reagent and analyte in the drop.
Sulfate Turbidimetry Detector Flowcell Light emitting diode Photodiode Method comparison 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

"Highly Sensitive Spectrophotometric Determination Of Nitrite Ion Using 5,10,15,20-tetrakis(4-aminophenyl)porphine For Application To Natural Waters"
Anal. Chim. Acta 1996 Volume 333, Issue 1-2 Pages 175-180
T. Kawakami and S. Igarashi*

Abstract: To 1 mL 0.05 mM 5,10,15,20-tetrakis(4-aminophenyl)porphine aqueous solution was added 1 mL 1 M HCl to give a final pH of 1 and a portion of standard nitrite (I) solution, and the mixture was diluted to 10 mL. After 30 min at 30°C, the change in absorbance due to diazotization was measured at 434 nm. The calibration graph was linear up to 0.4 µM-I (up to 18 ng/ml) with a detection limit of 4 nM (0.18 ng/ml). The RSD (n = 10) was 1% for 0.2 µM-I. Many foreign ions were tolerated in large amounts. The method was applied to the determination of nitrite in rain, spring and tap water. Interference by Fe(III) was masked by adding 1 mL 1 mM EDTA to the initial mixture. The results agreed with those obtained by ion chromatography and a FIA method.
Nitrite Spectrophotometry Interferences

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

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

"Flow Injection Analysis Of Copper Diethyldithiocarbamate In High Resistance Toluene Media Using A Microelectrode Detector"
Anal. Chim. Acta 1997 Volume 340, Issue 1-3 Pages 169-174
T. J. Cardwell*, J. H. Santos and A. M. Bond

Abstract: Copper diethyldithiocarbamate was detected in toluene based carrier streams, at a flow rate of 1.1 ml/min, containing either 0.03 M tetrahexylammonium perchlorate or 35% acetonitrile at a Pt microelectrode detector (5-25 µm radius) maintained at 1 V vs. Au. Calibration graphs were linear from 0.5 mM; detection limits were 0.1 µM (5 µm electrode) to 50 nM (25 µm electrode) with an injection volume of 50 µL. The method was used to determine Cu in standard and potable water samples following extraction as copper diethyldithiocarbamate into toluene. The results were verified by solvent extraction cathodic stripping voltammetry.
Copper Amperometry Electrode Electrode Sample preparation Solvent extraction Organic phase detection Method comparison Complexation

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

Abstract: The flow injection method for the determination of total As was based on the online reduction of As(V) to As(III) by ascorbic acid/KI reagent. Sample (100 µL) in a 4 M HCl carrier stream (9.5 ml/min) containing 0.5% ascorbic acid and 1% KI was propelled through a reaction coil (150 cm x 0.5 mm i.d.) at 140°C and a cooling coil (75 cm x 0.5 mm i.d.) at 10°C and then merged with 0.05 M NaBH4 (1.6 ml/min). The mixture was passed to a gas-liquid separator and arsine and H2 were swept to the atomizer cell (at 900°C) by an Ar carrier stream. The absorption signal for As was recorded at 193.7 nm. The same flow manifold was used for the selective detection of As(III) by using a carrier stream of 0.03 M HCl which did not contain the reducing reagents. The detection limits were 37 ng/l for total As and 111 ng/l for As(III). The RSD (n = 10) for 5 µg/l total As and As(III) were Calibration graphs were linear for 0.1-10 µg/l total As. The method was validated by analyzing certified drinking water using the multiple standard additions calibration procedure. A volume-based flow injection (FI) procedure is described for the determination and speciation of trace inorganic arsenic, As(III) and As(V), via hydride generation-atomic absorption spectrometry (HG-AAS) of As(III). The determination of total arsenic is obtained by online reduction of As(V) to As(III) by means of 0.50% (w/v) ascorbic acid and 1.0% (w/v) potassium iodide in 4 M HCl. The combined sample and reduction solution is initially heated by flowing through a knotted reactor immersed in a heated, thermostatted oil bath at 140°C, and subsequently, for cooling the reaction medium, a knotted reactor immersed in a water bath at 10°C. By using the very same volume-based FI-HG-AAS system without the heating and cooling reactors, and employing mild hydrochloric acid conditions, As(V) is not converted to arsine, thereby allowing the selective determination of As(III). The injected sample volume is 100 µl while the total sample consumption per assay is 1.33 ml, and the sampling frequency is 180 samples per hour. The detection limit (3s) for the online reduction procedure was 37 ng L-1 and at the 5.0 µg L-1, the relative standard deviation (RSD) was 1.1% (n=10) by calibrating with As(III) standards; by calibrating with As(V) standards the detection limit was 33 ng L-1 and the RSD was 1.3% (n=10). For the selective determination of As(III) the detection limit was 111 ng L-1 and the RSD was 0.7% (n=10) at 5.0 µg L-1. Both procedures are most tolerant to potential interferents. Thus, without impairing the assay, interferents such as Cu, Co, Ni and Se could, at a As(V) level of 5 µg L-1, be tolerated at a weight excess of 2000, 30000, 200 and 200 times, respectively. The assay of a certified drinking water sample by means of multiple standard addition (five levels; each three replicates) was 9.09±0.05 µg L-1 (certified value 9.38±0.71 µg l-1). 11 References
Arsenic(3+) Arsenic(5+) Spectrophotometry Volatile generation Standard additions calibration Reference material Heated reaction Redox Speciation Interferences Knotted reactor Volatile generation FIAS-400

"Standard Additions In Flow Injection Analysis With Atomic Absorption Spectrometry"
Anal. Chim. Acta 1997 Volume 357, Issue 1-2 Pages 151-156
B. Haghighi, N. Maleki and A. Safavi*

Abstract: A standard additions method in flow injection atomic absorption analysis has been described. The proposed method was applied to the determination of calcium in synthetic samples with and without chemical interference and the results were compared with those obtained by the conventional standard additions method in atomic absorption spectrometry. The influence of parameters of the how injection system was studied. The results showed that the proposed method was independent of such parameters. The relative standard deviations within and between analyzes were found to be 1.61 and 1.81%, respectively, at the 1.5 µg mL-1 Ca level. The method was used for the determination of calcium in tap water.
Calcium Spectrophotometry Interferences Optimization Sample splitting Standard additions calibration

"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

"Selective Flow Injection Quantitation Of Ultra-trace Amounts Of Chromium(VI) Via Online Complexation And Preconcentration With APDC Followed By Determination By Electrothermal Atomic Absorption Spectrometry"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 163-176
Steffen Nielsen and Elo H. Hansen

Abstract: A rapid, sensitive and selective time-based flow injection (FI) pre-concentration procedure is described for the determination of ultra-trace amounts of Cr(VI) via online reaction with ammonium pyrrolidine dithiocarbamate (APDC) and formation of the Cr(VI)-PDC complex. The pre-concentration is effected by adsorption on the inner wall of a knotted reactor made from PTFE tubing. The complex is subsequently eluted with a monosegmented discrete zone of ethanol (55 µL), and the analyte is quantified by electrothermal atomic absorption spectrometry (ETAAS). The operations of the FI-system and the ETAAS-detector are synchronously coupled. Efforts were made to design a generic and versatile FI-ETAAS system that allows all necessary manipulatory operations to be executed online which, in addition to effective entrapment of the analyte in the pre-concentration unit, comprise washing the surface of the retained analyte to remove possibly interfering matrix components; quant. dissolution of the retained analyte in the smallest possible volume of eluent to satisfy the volumetric requirements of the graphite tube (platform); reproducible transport of the concentrate to the ETAAS instrument at minimal dispersion; and, finally, a thorough cleansing of all pertinent conduits in the FI-system to prevent carry-over between individual samples. A 19-fold enhancement in sensitivity of Cr(VI) was achieved after pre-concentration for 60 s at a sample flow rate of 5.0 mL min-1 as compared to direct introduction of 55 µL samples, yielding a detection limit (3s) of 4.2 ng L-1. The sample frequency was 21.2 samples per h. The proposed method was evaluated by analyzing drinking water, a NIST Cr(VI)-ref. material and synthetic sea water. A major contribution to successful operation of the system can, to a large extent, be ascribed to the incorporation of a newly developed mixing-point component, which is attached directly to the commercial available 8-port rotary valve.
Chromium(VI) Spectrophotometry Preconcentration Ammonium pyrrolidine dithiocarbamate Knotted reactor Complexation Interferences Reference material Mixing Tube wall immobilization

"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

"Sequential Injection Sandwich Technique For The Simultaneous Determination Of Nitrate And Nitrite"
Anal. Chim. Acta 1998 Volume 371, Issue 1 Pages 63-71
A. Cerd&agrave;, M. T. Oms, R. Forteza and V. Cerd&agrave;*

Abstract: An automated sequential injection system for monitoring nitrate and nitrite in water samples is described. The method enables the simultaneous determination of both parameters with a single injection of sample. A sandwich arrangement, in which the sample is placed between two Griess reagent zones, is adopted. Nitrite is determined in one end of the sample zone by diazotization-coupling reactions and spectrophotometric detection of the azo dye formed. In the other end, nitrate is similarly determined after its online reduction to nitrite using a copperised cadmium column. The calibration is linear over the range 0.5-40 µmol L-1 nitrite and 2-100 µmol L-1 nitrate, the mid-range relative standard deviations being <2% in both the cases. Under optimized conditions the system has been applied to the determination of nitrate in tap, mineral and sea waters (the nitrite concentration. was below the detection limit) and the results have been compared with those obtained by ion chromatography and a flow injection system based on the same reactions.
Nitrate Nitrite Spectrophotometry Sequential injection Sandwich technique Simultaneous analysis Optimization Method comparison

"Fluorimetric Differential-kinetic Determination Of Silicate And Phosphate In Waters By Flow Injection Analysis"
Talanta 1986 Volume 33, Issue 11 Pages 889-893
P. Linares, M. D. Luque De Castro and M. Valcarcel

Abstract: The determination is based on the reaction of the sample with 0.02 M (NH4)6Mo7O24 - 0.48 M HNO3 - 0.24 M HClO4 with formation of silicate and phosphate heteropoly-acids at different rates, and subsequent oxidation of 0.03 M thiamine; the thiochrome produced is detected by fluorimetry at 440 nm (excitation at 375 nm) . Flow rates for sample, molybdate and thiamine solution are 3.0, 2.2 and 1.1 mL min-1, respectively. The flow injection configurations permit measurements at two different residence times for each sample. The anions are determined in the range 30 to 600 ng mL-1 in ratios from 1:10 to 10:1, with coefficient of variation <2%. Good results were obtained with samples of natural and potable water. The sampling rate is 60 h-1.
Phosphate Silicate Fluorescence Kinetic Simultaneous analysis

"Preconcentration And Separation Of Inorganic Selenium On Dowex 1X8 Prior To Hydride-generation Atomic Absorption Spectrometry"
Talanta 1994 Volume 41, Issue 1 Pages 67-74
Ulf &Ouml;rnemark* and &Aring;ke Olin

Abstract: Portions of 6 M and 1 M HCl were added sequentially to deaerated water samples (100 ml) of pH 9, containing 200 ng/l of Se(IV) and 27-216 ng/l of Se(VI), until a stable pink color (methyl red indicator) was observed. Ammonium chloride/ammonia buffer of pH 9, (0.4 ml) was added and the solution passed (2 ml/min) through 1 g (dry wt.) of conditioned Dowex 1X8 resin in chloride form (100-200 mesh; prep. described). Se(IV) was eluted with 10 mL of 0.025 M HCl and Se(VI) with 7.5 mL of 5 M HCl, flow rates 1 ml/min, prior to determination by hydride-generation (HG) AAS (Ibid., 1986, 33, 249). Recoveries of Se(IV) and Se(VI) were 98-102%. Total Se was determined as Se(VI), following the oxidation of Se(IV) to Se(VI) with KMnO4 (described) before pre-concentration and elution. Values of Se(IV) and total dissolved Se (tabulated) in drinking water and fresh water, obtained by the above enrichment procedure coupled with flow injection HG AAS, were in good agreement with those obtained by a HG AAS procedure which incorporated pre-concentration of Se as SeH4 in a liquid N2 trap.
Selenium Spectrophotometry Preconcentration

"Improvements In The NN-diethyl-p-phenylenediamine Method For The Determination Of Free And Combined Residual Chlorine Through The Use Of FIA"
Talanta 1991 Volume 38, Issue 2 Pages 145-149
G. Gordon, D. L. Sweetin, K. Smith and G. E. Pacey

Abstract: Buffer solution (pH 6.3) was mixed sequentially with NN-diethyl-p-phenylenediamine (I) solution and a stream of water containing the sample. After passage of the mixture through a 30-cm reaction coil, the absorbance of the solution was measured at 520 nm to give free Cl. For the determination of total Cl, the eluate was mixed with KI solution, passed through a 40-cm reaction coil and the absorbance of the solution was measured at 520 nm; combined Cl was determined by difference. The rectilinear range of the calibration graph was extended (to 0.1 to 8 mg L-1 of Cl) and coefficient of variation were improved (to 0.5 to 3%), compared with colorimetric or titrimetric methods involving I. The detection limit was 0.07 mg L-1 of Cl.
Chlorine, free Chlorine, residual Spectrophotometry Buffer Method comparison

"Determination Of Cadmium, Lead And Copper In Water Samples By Flame Atomic Absorption Spectrometry With Preconcentration By Flow Injection Online Sorbent Extraction"
Talanta 1991 Volume 38, Issue 6 Pages 613-619
Zhaolun Fang, Tiezheng Guo and Bernard Welz*,

Abstract: Sample was mixed with aqueous 0.05% diethylammonium diethyldithiocarbamate and the heavy metal complexes formed were concentrated on a 5-mm micro-column of Bakerbond C18 bonded silica (40 to 63 µm). The complexes were eluted with ethanol or methanol (2.5 mL min-1) and determined by flame AAS at 283.3, 228.8 and 324.7 nm, for Pb, Cd and Cu, respectively. The flow injection system is described in detail (diagrams given). The operating conditions were optimized and the methods was applied in the analysis of seawater, drinking water and a reference material. Results for the latter agreed with certified values. Recoveries of Cd and Pb from seawater and potable water were 94 to 102%. Detection limits were 0.3, 3 and 0.2 µg L-1 of Cd, Pb and Cu, respectively; coefficient of variation (n = 11) were 1.5%. Sampling rate was 120 h-1.
Cadmium Copper Lead Spectrophotometry Sample preparation Column Extraction Preconcentration Reference material C18 Optimization

"Electrocatalysis And Amperometric Detection Of Organic Peroxides At Modified Carbon-paste Electrodes"
Talanta 1991 Volume 38, Issue 10 Pages 1077-1081
Joseph Wang, Lucio Angnes and Chen Liang, Otis Evans

Abstract: Cobalt - phthalocyanine modified C paste electrodes were prepared by thoroughly mixing Co phthalocyanine with a 3:2 slurry of graphite powder (Acheson 38) and mineral oil (Aldrich). The catalytic behavior of the modified electrodes was exploited for developing an effective amperometric detection scheme for butanone peroxide, cumene hydroperoxide and tert-butyl hydroperoxide with optimum response at +0.7 V vs. Ag - AgCl. Highly sensitive and stable flow injection measurements, with detection limits of 2.4 to 8.3 ng and coefficient of variation of 1.7 to 1.8% (n = 30) were reported. The method is applied to drinking water.
Organics, peroxides Amperometry Electrode Catalysis Graphite Slurry

"Online Alumininium Preconcentration On Chelating Resin And Its Flow Injection Analysis - Spectrofluorimetric Determination In Foods And Dialysis Concentrates"
Talanta 1991 Volume 38, Issue 12 Pages 1387-1392
P. Fern&aacute;ndez, C. P&eacute;rez Conde, A. Guti&eacute;rrez and C. C&aacute;mara*,

Abstract: A selective and sensitive technique whereby Al is complexed with 5,7-dibromoquinolin-8-ol and extracted into ethyl ether before separation from interferants in a chelating micro-column and spectrofluorimetric determination at 525 nm (excitation at 400 nm). Other complexes and solvent systems are considered but are found to be inferior. Batch- and flow injection methods are studied and the latter is found to be the most selective. Optimum conditions are 0.05 M acetic acid buffer of pH 5.5 with complex concentration. in ethyl ether of 0.05%, aqueous and organic flow rates of 0.36 and 0.62 mL min-1, respectively, for a 185 µL sample injection volume. The calibration graph is rectilinear from 1 to 50 ng mL-1 of Al; detection limit is 0.3 ppb Al with coefficient of variation at 4 ppb of 3%. The method is applied in dialysis fluids, foods and tap water.
Aluminum Fluorescence Chelation Column Preconcentration PPB Interferences Dialysis Resin

"Determination Of Aqueous Ozone For Potable Water Treatment Applications By Chemiluminescence Flow Injection Analysis. A Feasibility Study"
Talanta 1992 Volume 39, Issue 6 Pages 593-598
Hyung-Keun Chung, Harvey S. Bellamy and Purnendu K. Dasgupta*,

Abstract: An inexpensive method of generating O3 at concentration. suitable for drinking-water sterilization is presented, together with the use of flow injection chemiluminescence analysis for selective determination of O3. The system comprised a multi-channel peristaltic pump, a dual-loop sample-injection value (electropneumatically actuated) and a laboratory-built flow-through reaction cell positioned in front of a photomultiplier tube. All tubing (0.5 mm diameter) was of PTFE. A number of fluorescing organic compounds was evaluated for the determination of aqueous O3. The limit of detection by using indigotrisulfonate was 2 µg l-1, but chromotropic acid, Rhodamine B (C. I. Basic Violet 10) and eosin Y may be more sensitive. The feasibility of determining aqueous O3 by chemiluminescence (CL) flow injection analysis was studied for application in potable water treatment. The ozonated water sample is injected into a pure water carrier and mixed with a dye reagent in front of a photodetector. Many reagents undergo fast CL reactions with aqueous ozone. Most of these reactions display considerable selectivity for O3 over other oxidants of importance in water treatment. Even when there is steady-state response to another oxidant, significant discrimination against the interferents is possible by taking advantage of the much faster kinetics of the CL reaction with O3. The design of an O3 generator and preparation of standard O3 solutions are described.
Ozone Chemiluminescence Low cost Apparatus Indirect Interferences

"Flow-cell Optosensor For Lead Based On Immobilized Dithizone"
Talanta 1992 Volume 39, Issue 11 Pages 1499-1503
Walace A. de Oliveira and Ramaier Narayanaswamy*

Abstract: Dithizone immobilized on XAD-4 resin was studied as the sensing element of an optical sensor for Pb using a flow-cell. Measurements were made using two different procedures. In 'kinetic analysis', the standard Pb solution was allowed to flow at a constant rate and the analytical signal was recorded as a function of time, whereas in the 'concentration procedure' only the initial and final values of reflectance were recorded, the light path being blocked during the addition of Pb solution and the regeneration of the reagent phase to avoid any photodegradation. Measurements were expressed as the relative reflectance, defined as the reflectance of the Pb complex minus that of the immobilized dithiozone alone. Lead in solution was determined from 0.3 to 10 µM with a detection limit of 10 nM. The sensor response was reproducible and could be regenerated using 10 mM HCl followed by citate - hydroxylamine solution The method may be applied in flow injection analysis and online analysis, and is suitable for most environmental analyzes, including drinking water.
Lead Sensor Flowcell Apparatus Resin Immobilized reagent Optosensing Kinetic Dithizone

"Design And Performance Of A New Continuous-flow Sample-introduction System For Flame Infrared-emission Spectrometry: Applications In Process Analysis, Flow Injection Analysis, And Ion-exchange High Performance Liquid Chromatography"
Talanta 1993 Volume 40, Issue 6 Pages 867-878
Christopher K. Y. Lam, Yunke Zhang, Marianna A. Busch and Kenneth W. Busch*,

Abstract: The cited system involves a specially designed purge cell to strip dissolved CO2 from solution into a H gas stream that serves as fuel for the hydrogen/air flame of the flame IR-emission (FIRE) radiometer. Sample stream is fed into the top of the cell through a PTFE tube and the H purge gas is supplied through a gas dispersion tube at the bottom of the cell. A side-arm links the cell to the FIRE burner and the spent analytical solution drains away through a bottom outlet. The system was applied in the process and FIA modes to the determination of total inorganic C in tap-water. In both modes the sample was mixed with 0.25 M HCl to release CO2. The procedure was extended to the determination of non-volatile organic materials by oxidizing the analytes to dissolved CO2 with peroxydisulfate in the presence of a Ag+ catalyst before purging. No details of detection limits or RSD are given.
Carbon, total Spectrophotometry

"Novel Ferroin Membrane Sensor For Potentiometric Determination Of Iron"
Talanta 1994 Volume 41, Issue 6 Pages 891-899
Saad S. M. Hassan* and Sayed A. M. Marzouk,

Abstract: Sodium tetraphenylborate solution (10 mM) and 10 mM ferroin [tris-(1,10-phenanthroline)iron(II)] were mixed for 5 min and the precipitate was collected, washed with water, dried for 24 h and finely ground. The powder was mixed with 2-nitrophenyl phenyl ether, PVC and THF, the solvent evaporated overnight and the resulting 0.1 mm thick membrane was fitted into a sandwich FIA cell. A Ag/AgCl internal reference wire electrode was immersed in a 10 mM ferroin/10 mM NaCl (1:1) internal reference solution The test solution was injected into a stream of 5 mM 1,10-phenanthroline and 10% hydroxylammonium chloride in 0.1 M acetate buffer of pH 4.7 in a FIA system, the solution passed through a mixing coil into a sandwich cell. The calibration graph was linear for 1-100 µM-ferroin, allowing the determination of total Fe. Fe(II) was determined batchwise by the omission of the hydroxylammonium chloride and the addition of EDTA. The removal of interfering anions is discussed. The method was applied to the determination of Fe in tap, underground, sea and mineral water, Al- and Cu-based alloys, cement, rocks and pharmaceutical preparations (details given). The recovery of 300 µg of Fe was 101.9% with RSD (n = 10) of 1.1%.
Iron Electrode Sensor Potentiometry Membrane Interferences

"Electroosmotic Flow And Injection: Application To Conductimetry"
Talanta 1994 Volume 41, Issue 10 Pages 1791-1795
Liang Tang and Calvin O. Huber*

Abstract: A technique for electroosmotic flow injection together with electroosmotic pumping using readily available fused-silica capillary tubing was investigated. A break was created in the capillary wall of a column (4-7 cm x 50-100 µm i.d.) near the end through which electrolytic contact with the capillary solution was established. The voltage at the break was monitored by potentiometry with a bridge configuration. A schematic diagram of the FIA system is given. The method was applied to the measurement of conductivity in tap water using 1 mM CaCl2 as a reference solution.
Conductivity Conductometry Potentiometry Electroosmotic flow

"Electrothermal Atomic Absorption Spectrometric Determination Of Ultratrace Amounts Of Tin By In Situ Preconcentration In A Graphite Tube Using Flow Injection Hydride Generation With Online Ion-exchange Separation"
Talanta 1995 Volume 42, Issue 3 Pages 375-383
Guanhong Tao and Zhaolun Fang*

Abstract: Geological samples (0.5 g) were treated with 5 mL HNO3/HF (7:3) at 40°C. After boiling nearly to dryness a further 2 mL acid was added. After cooling, the digests were diluted to 50 mL and 1 mL was diluted further to 100 mL with 2 M HCl. Hair (0.2 g) or 1 mL serum was acid-treated as above and then the digests were diluted to 50 mL with 2 M HCl. Tap water samples were filtered and acidified to 2 M HCl with concentrated HCl. The samples were passed through a microcolumn (3 cm x 3 mm i.d.) packed with anion-exchanger D-201 (Shenyang Organic Chemicals Co.). The Sn was retained as its chlorostannate complex and subsequently eluted with water into the hydride generation system. The hydride and H2 evolved were separated from the liquid phase in a gas-liquid separator and transferred into a Pd-coated graphite tube pre-heated to 300°C to collect the analyte which was later atomized at 2300°C, followed by AAS. Tin was determined at a sampling frequency of 30/hr with a detection limit of 0.01 µg/l. RSD were ~1.5%.
Tin Sample preparation Spectrophotometry Phase separator Preconcentration Reference material Volatile generation Ultratrace Volatile generation

"Flow Injection Analysis Chemiluminescence Detection Of Residual Ozone"
Talanta 1995 Volume 42, Issue 8 Pages 1045-1050
K. A. McGowan and G. E. Pacey*,

Abstract: Chemiluminescent reagents for the determination of residual ozone were compared. Each method was automated using gas diffusion flow injection analysis (diagram and description given). The reagents investigated were indigo disulfonate, indigo trisulfonate and luminol. The luminol method offered a much larger working range (48.4-155 µM-ozone) than the other two methods and the detection limit was 0.008 mg O3/l.
Ozone Chemiluminescence Gas diffusion Method comparison

"On The Spectrophotometric Flow Injection Determination Of Chromium(VI) In Natural Waters After Online Preconcentration On Activated Alumina"
Talanta 1995 Volume 42, Issue 11 Pages 1609-1617
Mauricio C. Pannain and Ricardo E. Santelli*

Abstract: A minicolumn made of silicone rubber (2.5 cm x 1.6 mm i.d.) was packed with 50 µL activated alumina (Brockman grade 1, particle size range 63-100 µm; Merck, Germany). Sample solution containing Cr(VI) was injected into the column at 5.1 ml/min. The column with adsorbed Cr(VI) was inserted into the eluting stream (0.1 M NH4OH; 2.73 ml/min) and the displaced Cr(VI) was then mixed with 0.7 M HNO3 (0.92 ml/min). The sample was then merged with the reagent stream (0.05% 1,5-diphenylcarbazide; 0.76 ml/min), the color was developed in a reaction coil and the absorbance was measured at 540 nm. Calibration graphs were linear from 10^-50, 2-10 and 1-5 µg/l for 5, 25 and 50 mL sample volumes, respectively. Corresponding detection limits were 3, 0.3 and 0.2 µg/l, respectively. The effects of interferents are tabulated. RSD were 0.6-4.7%. The method was used to determine of Cr(VI) in potable water. The feasibility of chromium(VI) pre-concentration on to activated alumina in a continuous-flow system with spectrophotometric detection was investigated. Chemical and flow variables, and the influence of concomitant species were studied both with and without pre-concentration systems. The best results were obtained by using a 2.5 cm long, 1.6 mm i.d. alumina minicolumn, and selecting 1 x 10^-4 M nitric acid as the pre-concentrating medium and 0.1 M ammonium hydroxide as the eluent. The eluted chromium(VI) was mixed with diphenylcarbazide in acidic medium and the absorbance of the colored complex was measured at 540 nm. Linear calibrations for 5, 25 and 50 mi sample volumes were established over the concentration ranges 10^-50 µg L-1, 2-10 µg L-1 and 1-5 µg L-1 with sensitivity enhancements of 44, 196 and 392 and detection limits (3s) of 3.0 µg L-1, 0.3 µg L-1 and 0.2 µg L-1, respectively. The method is relatively fast and cheap. Natural waters were analyzed with use of the developed procedure. (40 references)
Chromium(VI) Ion exchange Spectrophotometry Preconcentration Speciation Low cost Activated alumina Interferences

"Lead Determination At Ppb Level Using Stopped-flow FIA"
Talanta 1995 Volume 42, Issue 12 Pages 1857-1865
Mingshu Li and G. E. Pacey*

Abstract: A flow injection based kinetic method for the determination of lead ions was developed. In this method, resazurin was reduced to resorufin by sulfide and lead ions. The method has a detection limit of 1 ppb with a relative standard deviation of 5.2% at the 20 ppb level. Interferences can be removed by prior extraction. (28 References)
Lead Fluorescence Sample preparation Extraction Indirect Kinetic PPB Preconcentration Stopped-flow Interferences

"Application Of Sequential Injection Analysis To Anodic-stripping Voltammetry"
Talanta 1997 Volume 44, Issue 4 Pages 713-723
Ari Ivaskaa,* and Wladyslaw W. Kubiakb

Abstract: The system (diagram given) incorporated an eight-port value, PVC tubing (0.8 mm i.d.), holding and auxiliary coils (1.5 m), and a thin-layer detector cell with a vitreous-C working electrode, Ag/AgCl/3 M NaCl reference electrode and stainless-steel auxiliary electrode. Successive aspiration of stripping solution, deaerated 0.1 M HCl, sample, plating solution (10 µM-HgSO4 in 0.1 M HCl) and deaerated 0.1 M HCl was performed with the potential held at +0.5 V. Solutions stacked in the holding coil were pumped to the detector in reverse sequence. The generation of the Hg film on the electrode was followed by deposition of sample at -1 V, scanning to 0 V at 20 mV/s and measurement of the stripping current. Separation of Cd(II) and In(III) was achieved using 0.01 M EDTA in 2 M NaOH as stripping solution. Separation of Cd(II) and Tl(I) was achieved using 2 M ethylenediamine in 0.1 M HCl as stripping solution. Separation of Pb(II), Cd(II), Tl(I), Cu(II) and Sn(II) was achieved using a stripping solution giving 0.04 M EDTA, 0.8 M ethylenediamine in 0.8 M NH3 buffer of pH 9.8 at the detector. The calibration graph was linear for 30-175 nM-Pb in water and the detection limit was 25 nM. Sequential injection analysis (SIA) technique has been applied to anodic stripping voltammetry (ASV). The sample and reagent volumes can easily be controlled by SIA. The technique also allows plating of the mercury film online and therefore substantially reduces generation of mercury containing waste. Repeated sample passage through the detector was used during the deposition step to enhance the sensitivity. The way solution handling is done in SIA allows an easy and effective medium exchange procedure increasing the selectivity of the method. This has been demonstrated by changing the stripping medium and having different complexing agents in the stripping solution. The observed potential shifts of the stripping peaks could theoretically be explained in the cases where the complexation constants are known. Calibration and the standard addition methods are discussed and demonstrated by determining copper in tap water as a method of testing the procedure. (C) 1997 Elsevier Science B.V.
Lead(2+) Cadmium(2+) Thallium(I) Copper(II) Tin(II) Voltammetry Electrode Sequential injection Buffer

"Flow Injection Determination Of Lead And Cadmium Traces With Graphite Furnace Atomic Absorption Spectrometry"
Talanta 1997 Volume 44, Issue 5 Pages 867-875
M. Colognesi, O. Abollino, M. Aceto, C. Sarzanini and E. Mentasti*

Abstract: Natural or potable water sample, 10 mM Tiron solution (1,2-dihydroxy-3,5-benzenedisulfonic acid) and ammonium borate buffer of pH 9 were loaded at 1 ml/min into a pre-concentration manifold (diagram given) and pumped through a column (1.5 cm x 3.9 mm i.d.) of macroporous anion-exchange resin (AGMP-1; BioRad, 100-200 mesh, chloride form). The bound Pb and Cd were eluted with 0.1 M HCl and the eluate was collected in to a sampling cup for GFAAS using a matrix modifier of NH4H2PO4/magnesium nitrate. The program details are tabulated. Pb and Cd were determined at 283.3 nm and 228.8 nm, respectively. Recoveries were 92.7±0.4% for Pd and 28±1% for Cd. Using a batch method, Cd recoveries were higher. Detection limits were 9 and 7 ng/l for Pb and Cd, respectively, for a pre-concentration ratio of 5O. No calibration data are given. Interferences and the effect of Tiron purity were investigated.
Cadmium Lead Spectrophotometry Column Preconcentration Complexation Interferences Tiron Column Resin Biorad

"Equilibrium And Kinetic Properties Of A Fast Iminodiacetate Based Chelating Ion Exchanger And Its Incorporation In A FIA ICP-AES System"
Talanta 1997 Volume 44, Issue 6 Pages 1037-1053
Payman Hashemi* and &Aring;ke Olin

Abstract: Chelating ion-exchangers based on cross-linked agarose (Novarose; Scand Inovata AB, Stockholm, Sweden) were characterized for their metal binding abilities. Material with a metal binding capacity of 55 µmol/ml showed fast adsorption and desorption of Cu(II), Cd(II), Ni(II) and Ca(II) under both batch and column modes. When incorporated in a column (0.5 cm x 6 mm i.d.) in a FIA system (diagram given) quantitative adsorption of Cu(II), Cd(II) and Ni(II) occurred at flow-rates of up to 110 ml/min. Elution was achieved with 1 mL 1 M HCl at 4 ml/min for ICP-AES detection. Calibration graphs were linear for 15-120, 45-350 and 90-700 ng Cd(II), Cu(II) and Ni(II), respectively, and the detection limits were 2, 5 and 10 ng, respectively. RSD were 1.3-2.4%. The method was applied determine Cu and Cd in tap water at a flow rate of 60 ml/min.
Cadmium(2+) Calcium(2+) Copper(II) Nickel(II) Spectrophotometry Chelation Column Detection limit Resin Kinetic Iminodiacetate Preconcentration

"A Selective Optical Chemical Sensor For O-nitrophenol Based On Fluorescence Quenching Of Curcumin"
Talanta 1997 Volume 44, Issue 7 Pages 1319-1327
Ying Wang, Ke-Min Wang, Guo-li Shen and Ru-Qin Yu*

Abstract: A 4 µm thick membrane was prepared from 4 mg curcumin, 50 mg PVC and 100 mg tricresylphosphate in 2 mL THF. Two such membranes were mounted in a FIA detection cell (Zheng et al, Ibid., 1993, 40, 1569) and used for the determination of 2-nitrophenol (I) by fluorimetry at 512 nm (excitation at 426 nm) under batch conditions. Samples were prepared in acetate buffer of pH 4.8. Detection was based on the fluorescence quenching of curcumin by I. The calibration graph was linear for 0.15-10 mM and the detection limit was 80 µM. Selectivity decreased in the order I > 2,4-dinitrophenol > 3-nitrophenol > 4-nitrophenol > 2,4,6-trinitrophenol. RSD were The response was reversible and the response time was The sensor was used to determine I in potable water. Recoveries were 101-108%.
2-Nitrophenol Fluorescence Sensor PVC membrane Optosensing Indirect Quenching

"Flow Injection Analysis For Residual Chlorine Using Lead(II) Ion-selective Electrode Detector"
Talanta 1998 Volume 45, Issue 3 Pages 575-581
Aki Sakaia, Akihide Hemmia, Hiromitsu Hachiyaa, Fumie Kobayashia, Satoshi Itoa, Yasukazu Asanoa, Toshihiko Imatob,*, Yoshito Fushinukic and Isao Taniguchid

Abstract: A flow injection analysis (FIA) system for residual Cl in tap water uses a Pb(II) ion-selective electrode (ISE) detector and it is based on the specific response of the Pb(II)-ISE to residual Cl. The FIA system consists of a millivolt meter, a peristaltic pump, a Pb(II)-ISE detector and a recorder. A linear working curve between peak height and concentration. of residual Cl was obtained for 0.1-1 mg/L. The relative standard deviation for repeated injections of 0.2 mg/L residual Cl sample was 2%. The regression line and its correlation factor between the conventional o-tolidine colorimetric method and this method were Y = 0.75X+0.17 and 0.967, respectively, for this determination.
Chlorine, residual Electrode Indirect Method comparison

"Determination Of Arsenic(III) And Arsenic(V) By Electrothermal Atomic Absorption Spectrometry After-complexation And Sorption On A C-18 Bonded Silica Column"
Talanta 1998 Volume 45, Issue 6 Pages 1167-1175
Dirce Pozebon, Valderi L. Dressler, Jos&eacute; A. Gomes Neto and Adilson J. Curtius*

Abstract: A flow injection procedure for the separation and pre-concentration of inorganic arsenic based on the complexation with ammonium diethyl dithiophosphate (DDTP) and sorption on a C-18 bonded silica gel minicolumn is proposed. During the sample injection by a time-based fashion, the As3+-DDTP complex is stripped from the solution and retained in the column. Arsenic(V) and other ions that do not form complexes are discarded. After reduction to the trivalent slate by using potassium iodide plus ascorbic acid, total arsenic is determined by electrothermal atomic absorption spectrometry (ETAAS). Arsenic(V) concentration can be calculated by difference. After processing 6 mL sample volume, the As3+-DDTP complexes were eluted directly into the autosampler cup (120 µl). Ethanol was used for column rinsing. Influence of pH, reagent concentration, pre-concentration and elution time and column size were investigated. When 30 µl of eluate plus 10 µl of 0.1% (w/v) Pd(NO3)(2) were dispensed into the graphite tube, analytical curve in the 0.3-3 µg As L-1 range was obtained (r = 0.9991). The accuracy was checked for arsenic determination in a certified water, spiked tap water and synthetic mixtures of arsenite and arsenate. Good recoveries (97-108%) of spiked samples were found. Results are precise (RSD 7.5 and 6%, for 0.5 and 2.5 µg 1-1, n = 10) and in agreement with the certified value of reference material at 95% confidence level.
Arsenic(3+) Arsenic(5+) Arsenate ion Arsenite Spectrophotometry Diethyldithiophosphate C18 Silica gel Complexation Speciation Optimization Preconcentration Reference material

"The H-point And Generalized H-point Standard Additions Methods For Flow Injection Procedures"
Talanta 1998 Volume 47, Issue 1 Pages 193-202
P. Camp&iacute;ns-Falc&oacute;*, F. Blasco G&oacute;mez and F. Bosch-Reig

Abstract: This paper establishes the fundamentals of the H-point standard additions method (HPSAM) and generalized H-point standard additions method (GHPSAM) in the flow injection technique. Two kinds of anal. signals can be employed, FIA peaks and spectra. Different anal. problems were studied: determinations of one analyte in the presence or absence of matrix effect when different blank features are present, and determination of two analytes in the presence of blank bias error affecting the development of one of them. The determination of chloride with Hg thiocyanate which presents a matrix effect, and the determinations of Ca and/or Mg with arsenazo III were examined The methods were compared with conventional data treatment and proved able to isolate the analyte signal from the global one, thus providing accurate and precise results in the determination of the above mentioned species in bottled waters. No additional experimental work is needed to apply the methods.
Chloride Calcium Magnesium Spectrophotometry Standard additions calibration Interferences

"Low Pressure Chromatographic Separation Of Inorganic Arsenic Species Using Solid Phase Extraction Cartridges"
Talanta 1998 Volume 47, Issue 3 Pages 787-796
Serife Yal&ccedil;in and X. Chris Le*

Abstract: Routine water analysis of arsenic species requires simple, inexpensive, rapid and sensitive methods. To this end, we have developed two methods, which are based on the use of inexpensive solid phase extraction (SPE) cartridges as low pressure chromatographic columns for separation and hydride generation atomic absorption spectrometry (HGAAS) and hydride generation atomic fluorescence spectrometry (HGAFS) for detection of arsenic. Both anion exchange and reverse phase cartridges were successfully used to separate arsenite [As(III)] and arsenate [As(V)]. The composition, concentration, and pH of eluting buffers and the effect of flow rate were systematically investigated. Speciation of inorganic As(III) and As(V) were achieved within 1.5 min, with detection limits of 0.2 and 0.4 ng/ml, respectively. Both isocratic and step gradient elution techniques were suitable for the baseline resolution of As(III) and As(V) using anion exchange cartridges. Application of the methods to the speciation of As(III) and As(V) in untreated water, tap water, and bottled water samples were demonstrated. Results from the speciation of arsenic in a standard reference material water sample using these methods were in good agreement with the certified value and with inter-laboratory comparison results obtained using HPLC separation and inductively coupled plasma mass spectrometric detection (HPLC-ICPMS).
Arsenate ion Arsenic(3+) Arsenic(5+) Arsenite Sample preparation Fluorescence Solid phase extraction Speciation Volatile generation Reference material C18 Resin Column

"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

"Determination Of Analytical Parameters In Drinking Water By Flow Injection Analysis. 1. Simultaneous Determination Of PH, Alkalinity, And Total Ionic Concentration"
Analyst 1987 Volume 112, Issue 3 Pages 263-266
Francisco Ca&ntilde;ete, Angel R&iacute;os, Mar&iacute;a Dolores Luque de Castro and Miguel Valc&aacute;rcel

Abstract: The flow system described incorporates two detectors, a glass - calomel micro-electrode located in the sample stream (0.5 mL min-1) for continuous monitoring of pH and a spectrophotometer to monitor acid - base reactions. An injection valve in the sample stream diverts sample through an ion-exchange column of Dowex 50-X8 (H+ form) cationic resin and I is determined by titration of the acids formed against 0.5 mM NaOH with phenolphthalein as indicator. The alkalinity is determined by titration against 50 µM-HCl with methyl red as indicator. A microcomputer is used to collect and process data from both detectors. Results showed good agreement with those of conventional methods.
Alkalinity Ionic strength pH Electrode Electrode Spectrophotometry Method comparison Simultaneous analysis

"Determination Of Analytical Parameters In Drinking Water By Flow Injection Analysis. 2. Simultaneous Determination Of Calcium And Magnesium"
Analyst 1987 Volume 112, Issue 3 Pages 267-270
Francisco Ca&ntilde;ete, Angel R&iacute;os, Mar&iacute;a Dolores Luque de Castro and Miguel Valc&aacute;rcel

Abstract: The flow system described incorporates two valves to select the indicator and EDTA reagent solution required for the determination of Ca and the sum of Ca and Mg. Calcium is determined by titration with 5 mM EDTA in 0.5 M NaOH, with murexide as indicator and monitoring at 510 nm. The flow rate is 0.8 mL min-1 and sample volume is 1.93 mL. The sum of Ca and Mg is determined by titration with 5 mM EDTA with Eriochrome black T as indicator in NH4Cl - NH3 buffer (pH 10.8). A flow rate of 0.9 mL min-1 and injection volume of 1.8 mL are used and detection is at 520 nm. Concentrations are obtained from calibration graphs prepared with calibration standards for Mg in the presence of various concentration of calcium. Calibration graphs were rectilinear for 2 to 25 and 25 to 400 µg mL-1 of Ca and for 2 to 280 µg mL-1 of the sum of Ca and Mg. (For Part I see earlier in this section).
Calcium Magnesium Hardness Spectrophotometry Interferences Titrations

"Preconcentration And Determination Of Trace Amounts Of Lead In Water By Continuous Precipitation In An Unsegmented-flow Atomic Absorption Spectrometric System"
Analyst 1987 Volume 112, Issue 9 Pages 1233-1236
Pilar Mart&iacute;nez-Jim&eacute;nez, Mercedes Gallego and Miguel Valc&aacute;rcel

Abstract: Sample solution (10 to 250 ml) containing 0.3 to 15 µg of Pb(II) at pH 0.5 to 6 was pumped into the flow injection system (described) and mixed with 1.5 M NH3 in a coil (200 cm x 0.5 mm). The ppt. was retained on a stainless-steel filter and dissolved in 2 M HNO3 and Pb was determined by AAS. From 1.2 to 1500 ng mL-1 of Pb could be determined at a sampling rate of 1 to 15 h-1. The coefficient of variation were <3.6%. The effects of pH, flow rate and the geometrical characteristics of the coil were studied. The method was applied in the determination of Pb in tap-water.
Lead Spectrophotometry Optimization Precipitation Preconcentration

"Online Preconcentration And Determination Of Lead In Potable Water By Flow Injection Atomic Absorption Spectrometry"
Analyst 1988 Volume 113, Issue 1 Pages 125-128
Yanan Zhang, Philip Riby, Alan G. Cox, Cameron W. McLeod, Alan R. Date and Yuk Ying Cheung

Abstract: Water samples were adjusted to pH 2 with HNO3 and set aside for 24 h. To 100 mL of sample or standard solution was added 1 mL of 0.5 M tartaric acid and the pH was adjusted to ~6 with aqueous 2 M NH3. The flow injection manifold used is described; sample solution was injected into a carrier stream of aqueous 0.15 M NH3 and passed to a PTFE column (6 cm x 1.5 mm) of basic alumina, and the Pb - tartrate complex was eluted with 2 M HNO3 (250 µL) and determined by AAS at 283.3 nm with use of an air - acetylene flame. Calibration graphs obtained for various sampling times were typically rectilinear up to 100 µg L-1 of Pb. The detection limit was 0.36 µg L-1 of Pb. The coefficient of variation (n = 10) for 40 and 4 µg L-1 of Pb were 1.4 and 12%, respectively.
Lead Spectrophotometry Alumina Preconcentration

"Determination Of Trace Amounts Of Aluminum By Ion Chromatography With Fluorescence Detection"
Analyst 1988 Volume 113, Issue 4 Pages 641-644
Phil Jones, Les Ebdon and Tim Williams

Abstract: A sample solution (adjusted to pH 4 with dilute HNO3) was injected via a 100 µL loop on to a cation-exchange guard column (5 cm) of Dionex CG2 at 50°C; the mobile phase was 0.10 M K2SO4 (adjusted to pH 3.0 with dilute HNO3). Post-column derivatization was performed with 2 mM 8-hydroxyquinoline-5-sulfonate (adjusted to pH 8.3 with dilute aqueous NH3), with fluorimetric detection at 512 nm (excitation at 360 nm). The calibration graph was rectilinear from 5 µg L-1 to 10 mg L-1 of Al, and the detection limit was 1 µg L-1 of Al. A typical coefficient of variation was 3.4% (n = 8) at 0.25 mg L-1 of Al. Other commonly occurring metals did not interfere. The method was used to determine Al in a reference alloy and in tap water.
Aluminum HPIC Fluorescence Interferences Post-column derivatization Reference material 8-hydroxyquinoline-5-sulfonic acid Heated reaction

"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

"Rhodamine 6G Chemiluminescence For The Determination Of Free Chlorine In Tap-water By A Flow Injection Method"
Analyst 1989 Volume 114, Issue 10 Pages 1275-1278
Tatsuro Nakagama, Masaaki Yamada and Toshiyuki Hobo

Abstract: A reversed flow injection method is described, in which reagent is injected into the sample as carrier stream. Thus, sample was pumped (4.8 mL min-1) through a coil (2 m x 0.5 mm) at 60°C and a 20 µL portion of 3 mM rhodamine 6G was injected; the chemiluminescence was detected with a photomultiplier tube. The calibration graph was rectilinear from 0.2 (the limit of detection) to 30 µM-free chlorine (HOCl), and the coefficient of variation (n = 10) was 2.0% at 10 µM. The sampling rate was 240 h-1. Other inorganic species and chloramines did not interfere.
Chlorine Chemiluminescence Reverse Interferences

"Use Of Masking Agents In The Determination Of Lead In Tap Water By Flame Atomic Absorption Spectrometry With Flow Injection Preconcentration"
Analyst 1990 Volume 115, Issue 5 Pages 571-573
Stephen R. Bysouth, Julian F. Tyson and Peter B. Stockwell

Abstract: The selectivity of immobilized 8-hydroxyquinoline for lead is shown to be improved by the use of masking agents during pre-concentration, prior to determination by flame atomic absorption spectrometry. Interference by iron, copper, aluminum and zinc is suppressed by including triethanolamine, thiourea, fluoride, acetylacetone or cyanide in the buffer as masking agents. Species such as iron or copper can completely prevent the pre-concentration of lead. This is shown to be overcome by using a buffer consisting of 0.2 M boric acid, 2% triethanolamine, 2% thiourea and 2% acetylacetone, even when the interfering species is in a 200-fold excess over lead. Recoveries from tap water samples, to which various amounts of lead had been added, ranged from 94 to 108%. Results of analyzes of tap water samples using this method were in good agreement with those obtained by electrothermal atomic absorption spectrometry. A buffer consisting of 0.2 M H3BO3, 2% of triethanolamine, 2% of thiourea and 2% of acetylacetone was used in pre-concentration. of samples containing 50 ppm of Pb on a column of immobilized 8-hydroxyquinoline. Interferent ions at 200-fold excess can be tolerated but signal losses of 25% occur. Recoveries were from 94.9 to 107.7%. Results agreed with those from electrothermal AAS, losses in precision were overcome by careful flow-rate control.
Lead Spectrophotometry Preconcentration Interferences Buffer 8-Hydroxyquinoline Method comparison Chelation

"Determination Of Orthophosphate In Waters And Soils Using A Flow Analyser"
Analyst 1990 Volume 115, Issue 1 Pages 65-67
David J. Malcolme-Lawes and Koon Hung Wong

Abstract: Samples (0.3 ml) were injected into a high performance continuous-flow analyzer. (carrier 1.5% of NaCl in 0.12 M HNO3) downstream of the manifold where the reagents NH4MoO4, K - Sb tartrate (catalyst) and L-ascorbic acid were pre-mixed. Absorbance of the heteropolymolybdenum blue complex was measured at 670 nm. Interferences from ions commonly found in potable waters were small. The calibration graph was rectilinear for 100 ppm, and the detection limit was 4.8 ppb of P. Sample throughput was >120 h-1 at 4 ppm. The method was applied to soil samples after extraction with NaHCO3 solution
Phosphate Spectrophotometry Sample preparation Catalysis Interferences Calibration Detection limit PPB

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

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

"Spectrofluorimetric Determination Of Sulfate In Waters In Normal And Open - Closed Flow Injection Configurations"
Analyst 1991 Volume 116, Issue 3 Pages 305-307
Beatriz Fernandez-Band, Pilar Linares, M. D. Luque de Castro and Miguel Valc&aacute;rcel

Abstract: A 4 mM biacetyl mono-oxime nicotinoylhydrazone solution (1.02 mL min-1) was merged with 10 mM Zr(IV) in 2.4 M HCl (0.67 mL min-1), and this mixture was merged with sample in carrier solution (0.67 mL min-1) comprising 0.2 M NaOH or water for normal and open-closed systems, respectively. Fluorimetric detection was at 505 nm (excitation at 420 nm). In the open-closed system, the sample plug could be recirculated through the flow cell as required. For the normal system, the calibration graph was rectilinear for 2 to 30 and 30 to 150 µg mL-1, the coefficient of variation (n = 3) was 3.5% for 10 µg mL-1, and the sampling rate was 30 h-. Corresponding figures for the open-closed system were 1.5 to 150 µg mL-1, 2.3% and 6 or 12 h-1. Phosphate, MoO42-, F- and Fe(III) interfered in equimolar concentration. The method was applied to well, tap and bottled waters.
Sulfate Fluorescence Interferences Closed loop

"Determination Of 2,4-dimethylphenyl By Anodic Voltammetry And Flow Injection With Amperometric Detection At A Glassy Carbon Electrode"
Analyst 1992 Volume 117, Issue 12 Pages 1919-1923
Carolina Fern&aacute;ndez, Elena Chico, Paloma Y&aacute;&ntilde;ez-Sede&ntilde;o, Jos&eacute; M. Pingarr&oacute;n and Luis Ma. Polo

Abstract: Oxidation of 2,4-xylenol (I) at a vitreous-carbon electrode was studied by linear-sweep voltammetry (at rotating-disc or stationary electrodes), differential pulse voltammetry at a stationary electrode and flow injection analysis with amperometric detection (methods described). The working ranges of the differential-pulse voltammetric method with a pulse amplitude of 50 mV in 0.1 M HClO4 and in 0.1 M Britton - Robinson buffer (pH 10) were 2 to 35 µM and 2 to 40 µM with detection limits of 0.72 and 0.75 µM, respectively, and coefficient of variation of 2.4%. For flow injection, the calibration graphs were rectilinear from 0.01 to 4 mg l-1in 0.1 M HClO4 at +1.00 V and 0.01 to 5 mg L-1 in a 0.01 M Britton - Robinson buffer at +0.75 V, with detection limits of 33 nM and 58 nM of I, respectively, and coefficient of variation of 3.3 and 3.0%. Most other phenols interfere. Results are presented for samples of tap water and seawater; the flow injection method was simple, rapid and suitable for routine analysis of I in water. Mean recovery was >90%. An electroanal. study of the oxidation of 2,4-dimethylphenol (2,4-DMP) at a glassy C electrode in aqueous solutions using different voltammetric techniques was carried out. The results obtained with differential-pulse voltammetry, using a pulse amplitude of 50 mV, in 0.1 mol L-1 HClO4 and in a 0.1 mol L-1 Britton-Robinson buffer solution of pH 10.0 allowed the development of 2 methods for the determination of 2,4-DMP in the ranges at 2.0 x 10^-6-3.5 x 10^-5 and 2.0 x 10^-6-4.0 x 10^-5 mol L-1, with limits of detection of 7.2 x 10^-7 and 7.5 x 10^-7 mol L-1, respectively. Flow -injection methods with amperometric detection based on such an oxidation process are also described; calibration graphs were linear within the ranges 0.01-4.0 mg L-1 in 0.1 mol L-1 HClO4 at a potential of +1.00 V and 0.01-5.0 mg L-1 in a 0.01 mol L-1 Britton-Robinson buffer solution of pH 10.0 at a potential of + 0.75 V, with limits of detection of 4 and 7 µg L-1 (3.3 x 10^-8 and 5.8 x 10^-8 mol L-1) of 2,4-DMP, respectively. The proposed methods were applied to the determination of 2,4-DMP in water samples and good results were obtained.
2,4-Xylenol Voltammetry Electrode Amperometry Interferences

"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

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

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

"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

"Determination Of Ultratrace Amounts Of Selenium(IV) By Flow Injection Hydride-generation Atomic Absorption Spectrometry With Online Preconcentration By Coprecipitation With Lanthanum Hydroxide"
Analyst 1994 Volume 119, Issue 2 Pages 333-337
Guanhong Tao and Elo H. Hansen

Abstract: Water was filtered, acidified with concentrated HCl (10 ml/l) and boiled for 5 min. After cooling, NaOH was added to pH 3 and 0.5% lanthanum nitrate was added to a concentration of 20 mg/l. The resulting solution was mixed in a flow manifold (4 ml/min) with 0.2 M ammoniacal buffer solution of pH 9.1 (1.5 ml/min) and the precipitate formed was collected on the inner walls of a knotted reactor. After 100 s, the flow manifold configuration was changed so that the analyte was eluted from the reactor walls with 1 M HCl (9 ml/min). The eluate was merged with 0.3% NaBH4 in 0.05 M NaOH (1.5 ml/min) and the resulting stream was passed through a reaction coil (20 cm) and a gas-liquid separator, where H2Se was generated. The hydride, together with evolved H2 was swept into the atomizer and absorption was measured at 196.1 nm. The elution sequence lasted 10 s. Calibration graphs were linear from 0.01-0.5 µg/l of Se, with a detection limit of 0.001 µg/l. RSD for the determination of 0.5 and 0.1 µg/l of Se were 0.7% and 3.0%, respectively. Effects of co-existing ions were studied. The method was applied to natural and potable waters.
Selenium Spectrophotometry Preconcentration Volatile generation Coprecipitation Knotted reactor Phase separator Interferences Ultratrace Volatile generation

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

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

"Determination Of Aluminum In Water By Flow Injection With Fluorimetric Detection By Using Salicylaldehyde Carbohydrazone As Reagent In A Micellar Medium"
Analyst 1994 Volume 119, Issue 6 Pages 1221-1223
F. S&aacute;nchez Rojas, E. Crist&oacute;fol Alcaraz and J. M. Cano Pav&oacute;n

Abstract: Sample (390 µL) was injected into a carrier stream (1.4 ml/min) of potassium hydrogenphthalate/HCl buffer of pH 3.8. The solution was mixed with a stream (0.9 ml/min) of 1% Triton X-100 in DMF and then with a stream (0.9 ml/min) of 1 mM salicylaldehyde carbohydrazone in DMF. The fluorescence intensity of the medium was monitored fluorimetrically at 443 nm (excitation at 368 nm). A diagram of the manifold used is given. The calibration graph was linear from 3-600 ng/ml of Al with a detection limit of 2.25 ng/ml. The RSD (n = 11) for 50 and 200 ng/ml of Al were 3.55 and 4.99%, respectively. Recoveries were quantitative. The throughput was 56 samples/h. The method was applied to drinking water.
Aluminum Fluorescence Triton X Surfactant Micelle

"Determination Of Chloride Ions By Reaction With Mercury Thiocyanate In The Absence Of Iron(III) Using A UV-photometric, Flow Injection Method"
Analyst 1995 Volume 120, Issue 1 Pages 183-186
Joanne Cirello-Egamino and Ian D. Brindle

Abstract: The reaction between chloride ions and mercury(II) thiocyanate was studied and a method for the determination of chloride ions in water was developed. The sample (2.5-20 µL) was injected into a carrier stream (1.2 ml/min) of 0.023 and 0.035% mercury(II) thiocyanate. The sample plug passed through a knitted reactor (length 80 cm) before UV detection at 254 nm. The method was applied to tap water; the standard addition method was used for quantitation of chloride ions. The calibration graph was linear upto 40 µg/ml of chloride; the detection limit was 0.16 µg/ml. Sulfate, Mg(II) and Ca(II) ions did not interfere; bromide and iodide ions interfered at levels of 10^-100 µg/ml. The performance of the method was compared with that of the widely applied method for chloride determination in water in which Fe(III) is included as a reagent and the absorbance of the thiocyanate complex formed is measured at 450 nm. The results obtained from the two methods were statistically indistinguishable.
Chloride Spectrophotometry Indirect Interferences Method comparison Standard additions calibration Knotted reactor

"Pyoverdin-doped Sol-gel Glass For The Spectrofluorimetric Determination Of Iron(III)"
Analyst 1995 Volume 120, Issue 2 Pages 431-435
J. M. Barrero, C. C&aacute;mara, M. C. P&eacute;rez-Conde, C. San Jos&eacute; and L. Fern&aacute;ndez

Abstract: Pyoverdin was entrapped in sol-gel glass (details given) and used for the determination of Fe(III). Two methods, viz., continuous-flow and flow injection (FI), were used. In the continuous-flow method, Fe(III) solution in 0.05 M MES buffer of pH 6.5 (buffer A) was pumped (1.8 ml/min) through a flow cell filled with 200 mg of the pyoverdin-doped sol-gel glass (maintained at 4°C). The decrease in the fluorescence intensity was measured at 405 nm (excitation at 330 nm). Regeneration was effected with 1 M HCl. In the FIA method, Fe(III) solution (1 ml) was injected into a stream (1.2 ml/min) of buffer A and passed through the flow cell, and the fluorescence was measured as described above. For the continuous-flow method, the calibration graph was linear from 3 (detection limit) to 300 ng/ml of Fe(III) and the RSD (n = 10) was 3%. For the FIA method, the calibration graph was linear from 20 (detection limit) to 900 ng/ml of Fe(III) and the RSD (n = 10) was 4.5%. The continuous-flow method was applied to tap water and the FIA method to human serum.
Iron(III) Fluorescence Method comparison Indirect Sol-gel

"Arsenic In Ground Water In Six Districts Of West Bengal, India: The Biggest Arsenic Calamity In The World. 2. Arsenic Concentration In Drinking Water, Hair, Nails, Urine, Skin-scale And Liver Tissue Of The Affected People"
Analyst 1995 Volume 120, Issue 3 Pages 917-924
Dipankar Das, Amit Chatterjee, Badal K. Mandal, Gautam Samanta, Dipankar Chakraborti and Bhabatosh Chanda

Abstract: Hair (0.5-1 g) and nails (0.5 ng) were digested with HNO3 at 90-100°C for 5 min. Concentrated HNO3 was added and the solution was evaporated to 1 mL and diluted to 5 mL. Urine (1 ml) was heated with HNO3 and HClO4 until fumes were evolve and thus the flow injection thermospray system can be used over wide analytical ranges. Solutions containing up to 2% of NaCl could be injected without plugging of the thermospray vaporizer capillary.
Arsenic, total Arsenate ion Arsenite Dimethylarsinic acid monomethylarsonic acid Sample preparation Spectrophotometry

"Arsenic In Ground Water In Six Districts Of West Bengal, India: The Biggest Arsenic Calamity In The World. 1. Arsenic Species In Drinking Water And Urine Of The Affected People"
Analyst 1995 Volume 120, Issue 3 Pages 643-650
Amit Chatterjee, Dipankar Das, Badal K. Mandal, Tarit Roy Chowdhury, Gautam Samanta and Dipankar Chakraborti

Abstract: The As species present in the drinking water and urine of people in six districts of West Bengal affected by As-contaminated ground water were studied. The As species monitored were arsenite (I), arsenate (II), monomethylarsonic acid (III) and dimethylarsinic acid (IV). Four methods were used to determine I-IV in drinking water and/or urine: (i) separation of I and II from water with sodium diethyldithiocarbamate (NaDDTC) extraction followed by flow injection (FI) hydride-generation (HG) AAS determination; (ii) spectrophotometric determination of I and II from water with AgDDTC/CHCl3/hexamethylenetetramine as absorbing solution; (iii) separation of I-IV from water and urine by combined cation and anion-exchange resin columns followed by FI-HG-AAS determination; (iv) decomposition of total As in urine with HNO3/H2SO4/HClO4 followed by FI-HG-AAS. Results are discussed.
Arsenic, total Arsenate ion Arsenite Dimethylarsinic acid monomethylarsonic acid Spectrophotometry Spectrophotometry Sample preparation Extraction Method comparison Speciation Volatile generation Volatile generation

"Multicomponent Techniques In Sequential Injection"
Analyst 1995 Volume 120, Issue 4 Pages 1181-1184
E. G&oacute;mez, C. Tom&aacute;s, A. Cladera, J. M. Estela and V. Cerd&agrave;

Abstract: The use of sequential injection analysis (SIA) in conjunction with multicomponent techniques for the simultaneous determination of Ca and Mg is described. For SIA, a two-channel manifold was used: a 200 µL portion of a mixed reagent solution containing 1.2 mM 4-(2-pyridylazo)resorcinol and 0.5 M Tris buffer of pH 9.6 and 100 µL of sample were aspirated in that order. The mixture was propelled to the detector. The absorbance was measured at 500 nm from which the absorbance at 650 nm was subtracted in order to minimize effects from RI changes. The actual absorbance was determined by subtracting the blank absorbance from that for the sample. The spectra obtained were resolved using a multi-linear regression program (cf. Cladera et al., Anal. Chim. Acta, 1992, 267, 95). A diagram of the SIA set-up used is given. Calibration graphs were linear from 1-20 and from 2-40 mg/l of Mg and Ca, respectively. The RSD (n = 10) for 10 mg/l each of Mg and Ca were 4 and 2%, respectively. The throughput was 60 samples/h. The method was used to determine Ca and Mg in drinking and waste water. The results were compared with those obtained by batch- and flow injection analysis.
Calcium Magnesium Spectrophotometry Multicomponent Multivariate calibration Refractive index Sequential injection

"Online Preconcentration Of Silver On A Sulfhydryl Cotton Microcolumn And Determination By Flow Injection Atomic Absorption Spectrometry"
Analyst 1995 Volume 120, Issue 7 Pages 1911-1915
M. M. G&oacute;mez G&oacute;mez, M. M. Hidalgo Garc&iacute;a and M. A. Palacios Corvillo

Abstract: A flow injection AAS method for Ag determination in water is described. The sample (15 ml) was adjusted to pH 1.5-2 with HNO3. It was then pumped into a carrier stream (3 ml/min) of 0.05 M HNO3 and passed through a column (7 cm x 1.5 mm i.d.) packed with sulfhydryl cotton fiber (pre-concentration time 5 min). The adsorbed Ag was eluted from the column by injecting 50 µL of 0.2 M KCN into the HNO3 carrier stream (1 ml/min) and was determined by AAS at 328.1 nm using an air/acetylene flame. The calibration graph was linear from 0-50 µg/l of Ag; the detection limit was 1 µg/l. The RSD (n = 5) for 10 µg/l of Ag was 3.5 %. The throughput was 9 samples/h. Recoveries of Ag were 98-108%. The method was applied to tap water.
Silver Spectrophotometry Column Preconcentration Sulfhydryl cotton

"Sensitive Determination Of Manganese Using Flow Injection And Chemiluminescent Detection"
Analyst 1995 Volume 120, Issue 8 Pages 2119-2127
Andrew R. Bowie, Peter R. Fielden, Roger D. Lowe and Richard D. Snook

Abstract: A reagent stream (3.7 ml/min) consisting of 0.25 mM 7,7,8,8-tetracyanoquinodimethane/4 mM didodecyldim ethylammonium bromide/0.3 mM Eosin Y and a stream (3.7 ml/min) of 0.01 M NaOH were mixed in a 2 m coil. The mixed stream was transferred to a spiral flow cell where it was mixed with an aqueous carrier stream (3.7 ml/min) into which the sample (90 µL) had been injected. The chemiluminescence intensity produced was measured. Three flow regulators (each consisting of 1 m of coiled tubing) were employed on each of the stream lines to act as pulse dampeners. Diagrams of the manifold and spiral flow cell used are given. The calibration graph was linear from 0-100 ppb of Mn, the detection limit was 4.5 ppb and the RSD (n = 20) was 4.9-5.3%. Interference from Fe was masked with desferrioxamine and the standard additions method was used for quantification of Mn. The method was applied to the analysis of Mn in potable water. The results obtained showed reasonable agreement with those obtained by electrothermal AAS.
Manganese Chemiluminescence Method comparison Interferences Pulse dampener Standard additions calibration

"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

"Flow Injection Spectrofluorimetric Determination Of Fluoride Or Phosphate Based On Their Inhibitory Effect On The Photo-oxidation Of Acridine Catalysed By Iron(III)"
Analyst 1996 Volume 121, Issue 4 Pages 477-481
Tom&aacute;s P&eacute;rez-Ruiz, Carmen Mart&iacute;nez-Lozano, Virginia Tom&aacute;s and Antonio Sanz

Abstract: A stream (1 ml/min) of 0.5 mM iron(III) perchlorate in 5 mM HClO4, adjusted to pH 2.6, was mixed with the sample stream (1 ml/min). A portion (185 µL) of 0.1 mM acridine of pH 2.6 was injected into the mixture, which then passed into a photoreactor, consisting of PTFE tubing (150 cm x 0.5 mm i.d.) wound round a UV quartz pencil lamp. When the sample zone reached the photoreactor, the flow was stopped and irradiation was performed for 60 s. The flow was then re-started and the fluorescence intensity of the irradiated sample zone was measured at 472 nm (excitation at 350 nm). The calibration graphs were linear for 10^-100 and for 40-500 µM phosphate and fluoride, respectively. Detection limits were 3.2 µM phosphate and 13 µM fluoride. The within-day RSD (n = 10) were 0.8-1.2% and 0.6-0.9% for phosphate and fluoride, respectively; the between-day RSD (n = 3) were 1.8% for phosphate and 2.1% for fluoride. The throughput was 45 samples/h. Recoveries of phosphate and fluoride from synthetic water samples were 99-105% and 95-103%, respectively. The method was used to determine fluoride in mineral water.
Fluoride Phosphate Fluorescence Stopped-flow Photochemistry UV reactor

"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

"Technique And Support For Micro-organism Immobilization. Application To Trace Metals Enrichment By Flow Injection Atomic Absorption Spectrometry"
Analyst 1996 Volume 121, Issue 11 Pages 1633-1640
Angel Maquieira, Hayat A. M. Elmahadi and Rosa Puchades

Abstract: The fungus Penicillium notatum was covalently immobilized on glutaraldehyde-treated controlled-pore glass and sand. Two methods for dissolution of the fungus before immobilization were employed, viz., (i) treatment NaOH and (ii) ultrasonic agitation. The immobilized fungus was incorporated in a flow injection AAS system to assess effectiveness in pre-concentrating various metals, viz., Cu, Cd, Fe, Pb and Zn, from aqueous solution. Detection limits in the ng/ml range were achieved, with enhancement factors of 14-625 depending on the metal and on the method and support used to immobilize the fungus. The pre-concentration method was used to determine Cu and Zn in tap and mineral water. The results obtained agreed with those obtained by voltammetry.
Copper Trace elements Spectrophotometry Controlled pore glass Preconcentration Immobilized fungi

"Solid-phase Extraction Coupled With Electrochemical Detection For The Determination Of The Herbicide Bromofenoxim In Water Samples At Low- And Sub-micro G 1-1 Levels"
Analyst 1996 Volume 121, Issue 12 Pages 1839-1843
Irena Grabec vegl, Boidar Ogorevc, Milko Novi and Emilio Benfenati

Abstract: A sample (100-250 ml) was adjusted to pH 3 with HClO4 and pumped through a C18 Polar Plus silica gel SPE cartridge, previously conditioned with acetonitrile/H2O then dried. For square-wave voltammetric detection, bromofenoxim (I) was eluted with 10 mL acetonitrile containing 0.1 M LiClO4. The eluate was analyzed directly at a static Hg drop electrode by applying a depoon potential of -0.1 V vs. Ag/AgCl for 10 s followed by a potential scan to -0.8 V, at 175 Hz, a pulse amplitude of 30 mV and a potential step of 10 mV. For FI amperometric detection, I was eluted with 10 mL 20% aqueous acetonitrile containing 0.1 M LiClO4 (solution A). A portion of eluate (40 µL) was injected into a carrier stream of solution A at a flow rate of 0.5 ml/min. Detection was at an in situ prepared Hg-film eous C electrode at -0.7 V vs. Ag/AgCl. For square-wave voltammetric detection, the calibration graph was linear from 0.2-12 µg/l I; the detection limit was 0.05 µg/l. Recovery was 92% and RSD was 6% (n = 6). For FI amperometric detection, the calibration graph was linear from 3-120 µg/l I; the detection limit was 1.5 µg/l. The recovery was 121% and RSD was 9% (n = 7). The methods were applied to tap water.
Bromofenoxim Amperometry Sample preparation Solid phase extraction

"Determination Of Copper(II) By Anodic-stripping Voltammetry Using A Flow-through System"
Analyst 1996 Volume 121, Issue 12 Pages 1903-1906
A. Economou and P. R. Fielden

Abstract: An automated flow system for Cu determination by anodic stripping voltammetry is described. The system (diagram given) could be operated in either flow injection (FI) or continuous-flow (CF) mode. Two types of flow-through cell, viz., a wall-jet or a thin-layer cell, were employed and Hg-plated vitreous C micro- or macro-electrodes were used as the working electrode. In the FI mode, the sample (100 µL) was injected into a carrier stream of 0.1 M HNO3 at a flow rate of 2 ml/min while the working electrode was held at -0.4 V vs. Ag/AgCl. The flow was then stopped; after a 10 s rest period, a potential scan to 0.1 V was initiated. In the CF mode, the sample was drawn at a flow rate of 1 ml/min through the working electrode held at -0.4 V. After 20 min, the cell was washed with 0.1 M HNO3. The flow was stopped and, after a 10 s rest period, the potential was scanned to 0.1 V. The FI method was applied to the analysis of tap water and pharmaceuticals; the CF method was applied to seawater analysis (results presented).
Copper Voltammetry Electrode Electrode Electrode Stopped-flow

"Simultaneous Spectrofluorimetric Determination Of Selenium(IV) And (VI) By Flow Injection Analysis"
Analyst 1997 Volume 122, Issue 3 Pages 221-226
M. J. Ahmed, C. D. Stalikas, P. G. Veltsistas, S. M. Tzouwara-Karayanni and M. I. Karayannis

Abstract: A sample (100 µL) was injected into a carrier stream of 2 M H2SO4 at a flow rate of 0.1 ml/min and mixed with a reagent stream of 0.2 mM 2-(α-pyridyl)thioquinaldinamide in propan-2-ol at a flow rate of 0.3 ml/min. The fluorescence intensity due to Se(IV) was measured at 500 nm (excitation at 350 nm). A second portion (100 µL) was then injected into the carrier stream and passed through a coil (40 cm x 0.8 mm i.d.) where it was irradiated at 254 nm. The irradiated sample stream was then mixed with the reagent stream and the fluorescence intensity due to total Se was measured. Se(VI) was determined from the difference in the two fluorescence intensity values. The calibration graphs were linear from 0.01-2.2 and 0.1-2.4 µg/ml Se(IV) and Se(VI), respectively; corresponding detection limits were 1 and 10 ng/ml. RSD were 0.1-2% (n=5). The throughput was 25 samples/h. The method was applied to the analysis of alloys, hair, tap and lake water, sediments, soil, tea, flour and eggs. A simple, sensitive, highly selective, automatic spectrofluorimetric method for the simultaneous determination of selenium (IV) and (VI) as selenite-selenate by flow injection analysis (FIA) has been developed. The method is based on the selective oxidation of the non-fluorescent reagent 2-(α-pyridyl)thioquinaldinamide (PTQA) in acidic solution (1.5-3.0 M H2SO4) by Se(IV) to give an intensely fluorescent oxidation product (lambda ex =350 nm; lambda em = 500 nm). Selenium (VI) is reduced online to Se(IV), in a reduction coil installed in a photo- reactor, which is then treated with PTQA and the fluorescene due to the sum of Se(IV) and Se(VI) is measured; Se(Vi) is determined from the difference in fluorescence values. Various analytical parameters, such as effect of acidity, flow rate, sample size, dispersion coefficient, temperature, reagent concentration and interfering species were studied. The photo-reduction conditions were optimized, with an FIA procedure, for Se(VI) on the basis of its reduction efficiency. The calibration graphs were rectilinear for 0.1-2.4 µg mL-1 of Se(VI) and 10 ng mL-1 - 2.2 µg mL-1 of Se(IV), respectively. The method was applied to the determination of Se in several Standard Reference Materials (alloy, sediments and tea), as well as in some environmental waters (tap and surface water), food samples (flour and egg), a biological sample (human hair), soil sample and in synthetic mixtures. Up to 25 samples per hour can be analyzed with an RSD approximately 0.1-2%.
Selenium(IV) Selenium(VI) Fluorescence Speciation Photochemistry Selectivity Reference material Interferences

"Determination Of Primary Explosive Azides In Environmental Samples By Sequential Injection Amperometry"
Analyst 1997 Volume 122, Issue 4 Pages 315-319
Roger T. Echols, Ryan R. James and Joseph H. Aldstadt

Abstract: A method for determining the azide ion in water is described. The sample (~333 µL) was loaded into a holding coil then propelled by a carrier (donor) stream of 0.01 M KCl in phosphate buffer of pH 3.78 at a flow rate of 1 ml/min to a gas diffusion unit. In the gas unit, HN3 diffused across a PTFE membrane into a static acceptor stream of 0.01 M KCl in phosphate buffer of pH 6.6. Diffusion of HN3 was enhanced by carrying out four reverse and forward flows of the sample zone, after which the flow of the acceptor stream was started at a rate of 1 ml/min. The analyte was detected amperometrically at a vitreous C electrode at 1 V vs. Ag/AgCl. A diagram of the manifold used is given. The calibration graph was linear up to 0.5 ppm azide; the detection limit was 24.6 ppb. RSD was 1.7-7.7% (n = 4). The method was applied to the analysis of lake, tap and groundwater.
Azide ion Amperometry Electrode Sequential injection Gas diffusion Microporous membrane Teflon membrane

"Determination Of Phenoxy Acid Herbicides From Aqueous Samples By Improved Cleanup On Polymeric Pre-columns At High Ph"
Analyst 1997 Volume 122, Issue 9 Pages 889-893
Ren&eacute; B. Geerdink, Sylvia van Tol-Wildenburg, Wilfried M. A. Niessen and Udo A. Th. Brinkman

Abstract: An improved procedure for the determination of phenoxy acid herbicides in environmental water samples is reported. The procedure consists in solid-phase extraction (SPE) of 60 mL water samples on a polymeric pre-column at pH 2.8, a clean-up step at high pH and subsequent desorption and ion-pair LC separation at pH 8.8, The main improvements are in the basic clean-up step and in the LC eluent composition, The release of compounds which are electrostatically bound to the pre-column is favoured by a washing step with 0.1 mol L-1 sodium hydroxide solution, As regards LC, gradient elution is applied using solvents with low buffer and ion-pairing concentrations. The detection limits for the phenoxy acids (UV detection at 232 nm) are 5-20 ng L-1 for tap water samples, At the 0.1 µg L-1 spiking level, the RSD is 6% (n = 7) and the recoveries are better than 83% for all analytes. The long-term reproducibility typically has RSD values of 5% (n = 7), The method was successfully tested on water samples from various origins, and the results obtained with the present online SPE-LC-UV procedure mere found to compare well with those obtained with procedures involving SPE combined off-line with GC-MS or flow injection MS-MS. 12 References
Herbicides, phenoxy acid Mass spectrometry Method comparison

"Optimization Of A Flow Injection Differential Potentiometric System With Two Identical Electrodes For The Determination Of Calcium-ion In Water With Improved Sensitivity"
Analyst 1997 Volume 122, Issue 11 Pages 1435-1443
Luis M. B. C. &Aacute;lvares-Ribeiro and Ad&eacute;lio A. S. C. Machado

Abstract: An experimental optimization by the modified simplex method of a flow injection analysis (FIA) system for the differential potentiometric determination of calcium ion in mater is reported, The performances of the optimized system and of an equivalent conventional potentiometric FIA system are compared, The most important features of the proposed system are a substantial increase in sensitivity (from about 28 to shout 50 mV per decade) in the linear response range (10^-4 - 10^-2 mol L-1 in both cases) and better repeatability (0.5 and 0.8% versus 1.7 and 1.9%, respectively, at 1 x 10^-3 and 6.2 x 10^-4 mol L-1 calcium ion), The influence of the ionic strength is discussed, showing that it significantly affects the accuracy of the results. The relative accuracy of the differential system was demonstrated try the determination of the calcium content of drinking Waters in parallel with an ASTM certified method. 26 References
Calcium Potentiometry Simplex Optimization Method comparison Sensitivity Ionic strength Standard method Reference material

"Speciation Analysis Of Chromium(III) And Chromium(VI) Using Flow Injection Analysis With Fluorometric Detection"
Analyst 1998 Volume 123, Issue 5 Pages 1005-1009
Evangelos K. Paleologos, Spyros I. Lafis, Stella M. Tzouwara-Karayanni and Miltiades I. Karayannis

Abstract: A relatively simple, sensitive, selective, automatic fluorometric method for the simultaneous determination of Cr(III) and Cr(VI) by flow injection analysis (FIA) was developed. The method is based on the selective oxidation of the nonfluorescing reagent 2-(α-pyridyl)thioquinaldinamide (PTQA), which with Cr(VI) yields an intensely fluorescent product (λex = 360 nm; λem = 500 nm). Cr(III) is oxidized online to Cr(VI) with sodium metaperiodate and the Cr(VI) is subsequently treated with PTQA. Fluorescence due to the sum of Cr(III) and Cr(VI) is measured and Cr(III) is determined from the difference in fluorescence values. The effects of various anal. parameters, such as acidity, flow rate, sample volume, temperature, reagent concentration and interfering species, were studied. Kinetic studies using both the stopped-flow technique and the FIA procedure were used to study and optimize the oxidation conditions for Cr(III) from its oxidation efficiency. The calibration graphs were rectilinear in the ranges 0.1-10 µg mL-1 for Cr(VI) and 0.1-1.0 µg mL-1 for Cr(III). The method was successfully verified by performing recovery experiments of Cr in several standard reference materials (peach leaves, sediments and tea), and it was applied to the speciation analysis of Cr(III)-Cr(VI) in environmental waters (mineral, tap and distilled water), a food sample (tomato juice) and synthetic mixtures. Up to 30 samples per h can be analyzed with a relative standard deviation of ~0.1-2%.
Chromium(III) Chromium(VI) Fluorescence Speciation Stopped-flow Kinetic Reference material Indirect Interferences Optimization

"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

"Flow Injection Ion-exchange Preconcentration For The Determination Of Aluminum By Atomic Absorption Spectrometry And Inductively Coupled Plasma Atomic Emission Spectrometry"
J. Anal. At. Spectrom. 1987 Volume 2, Issue 7 Pages 699-703
M. R. Pereiro Garc&iacute;a, M. E. D&iacute;az Garc&iacute;a and Alfredo Sanz Medel

Abstract: For the pre-concentration. of Al in solution (e.g., potable waters or haemodialysis fluids), sample (1 ml) was injected into a carrier stream (1.5 mL min-1) of 50 mM 2-(N-morpholino)ethanesulfonic acid - NH3 buffer (pH 7) and passed through a mini-column of Amberlite IRA-400 (~0.108 g). The resin was washed before use to remove Al. After ~2 min, a 'plug' (75 µL) of 1 M NaOH was injected on to the column and the stripped Al was determined by flame AAS at 309.6 nm or by ICP-AES at 396.15 nm. Determination in the ng L-1 range was possible by either technique. Aluminum in serum is too tightly bound by proteins to be retained by the mini-column. For the pre-concentration. of Al in solution (e.g., potable waters or haemodialysis fluids), sample (1 ml) was injected into a carrier stream (1.5 mL min-1) of 50 mM 2-(N-morpholino)ethanesulfonic acid - NH3 buffer (pH 7) and passed through a mini-column of Amberlite IRA-400 (~0.108 g). The resin was washed before use to remove Al. After ~2 min, a 'plug' (75 µL) of 1 M NaOH was injected on to the column and the stripped Al was determined by flame AAS at 309.6 nm or by ICP-AES at 396.15 nm. Determination in the ng L-1 range was possible by either technique. Aluminum in serum is too tightly bound by proteins to be retained by the mini-column.
Aluminum Ion exchange Spectrophotometry Spectrophotometry Preconcentration Amberlite Resin Column Dialysis

"Chelating Resins For Online Flow Injection Preconcentration With Inductively Coupled Plasma Atomic-emission Spectrometry"
J. Anal. At. Spectrom. 1989 Volume 4, Issue 6 Pages 509-518
Xiarou Wang and Ramon M. Barnes

Abstract: A poly(dithiocarbamate) (PDTC) and a methylcarboxylated poly(ethylenimine) - poly(methylenepolyphenylene) isocyanate (CPPI) chelating resin were evaluated for the online pre-concentration. of 22 elements, with subsequent elution and detection by ICP-AES. The effect of pH on recovery of elements and of parameters, such as column length and diameter, which affect the dispersion of the analyte zone were studied. The PDTC resin works effectively at pH 8 to 10, whereas the CPPI resin chelated successfully at pH 5 to 6. Some elements could be pre-concentrated on one resin only. The PDTC resin was applied in the determination of Cu and Zn in natural and drinking water. Recovery of Cu was 98% at 20 and 50 ng mL-1, and the coefficient of variation (n = 11) was ~3% for 100 ng mL-1 of Cu.
Copper Zinc Spectrophotometry Column pH Chelation Resin Preconcentration Multielement

"Combination Of Flow Injection Hydride Generation And Sequestration On A Graphite Tube For The Automated Determination Of Antimony In Potable And Surface Waters"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 2 Pages 433-438
Hans-Werner Sinemus, Joachim Kleiner, Hans-Henning Stabel and Bernard Radziuk

Abstract: Filtered samples of surface and potable water were acidified by addition of HCl to a final concentration. of 0.2M. The solution were mixed with 32% HCl followed by 3% KI - 5% ascorbic acid for reduction of SbV to Sb(III); the reduction time was reduced to 2 h with aqueous 10% hydroxylammonium chloride and interference from NO2- was eliminated with 15% sulfonic acid. The resulting solution was injected into a stream of NaBH4 in a fully automated microcomputer-controlled FIAS-200 flow injection system for generation of SbH3. The SbH3 was separated with a gas - liquid separator and transferred to a Perkin-Elmer HGA-500 graphite furnace for electrothermal AAS. The limit of determination was 20 pg with a detection limit of 15 pg. A method for the determination of Sb in potable and surface waters combines a flow injection app. for hydride generation with sequestration of Sb on a graphite tube, followed directly by atomization and measurement of atomic absorption. The entire measurement procedure and the acquisition of data were under microcomputer control, permitting fully automatic operation and improving measurement precision. Sample volumes of 500 µL can be manipulated using a sample loop and injection valve, whereas for larger volumes a continuous-flow technique has to be used. A study of recovery demonstrated that >90% of the Sb contained in sample volumes of 5 mL was retained on the surface of an uncoated electrographite tube. Statistical evaluation of calibration data yielded a limit of determination of 20 pg and a limit of detection of 15 pg. The method was applied to the depth profiling of total and dissolved Sb in lake water. In Lake Constance, a max. particle-bound concentration. of 25 ng/L was measured.
Antimony Spectrophotometry FIAS-200 Computer Automation Volatile generation Interferences Volatile generation

"Determination Of Trace And Ultratrace Amounts Of Germanium In Environmental Samples By Preconcentration In A Graphite Furnace Using A Flow Injection Hydride-generation Technique"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 4 Pages 577-584
Guanhong Tao and Zhaolun Fang

Abstract: Trace and ultratrace levels of Ge were determined using flow injection (FI) hydride-generation followed by trapping and electrothermal atomization. Samples of garlic, tap water, ginseng and geochemical reference materials were pre-treated (details given) and diluted with 0.15 M or 3 M HCl then propelled into the FI system and merged with a tetrahydroborate reductant. This generated hydrides together with some H, which were separated in a gas - liquid separator, transferred to a Pd-coated graphite furnace pre-heated to 400°C and atomized by heating to 2500°C. Sensitivities and interference effects using different concentration. of HCl were compared. The use of high acidities and FI rather than batch collection led to reduced interference. Interference studies of 13 metals were performed (results given). Calibration graphs were rectilinear up to 0.5 µg L-1 of Ge for use of 0.15 M HCl and up to 2.5 µg L-1 for use of 3 M HCl with detection limits of 0.004 and 0.03 µg l-1, respectively, using 4.5 mL of sample. Coefficients of variation (n = 11) were 2.0% at 0.3 µg L-1 of Ge in 0.15 M HCl and 2.5% at 1.5 µg L-1 in 3 M HCl.
Germanium Spectrophotometry Phase separator Interferences Reference material Preconcentration Ultratrace

"Ultratrace Determination Of Cadmium By Vapor Generation Atomic-fluorescence Spectrometry"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 5 Pages 723-729
Les Ebdon, Phillip Goodall, Steve J. Hill, Peter B. Stockwell and K. Clive Thompson

Abstract: A commercial hydride generator was used with continuous-flow methodology for generation of volatile Cd-containing species with use of sodium tetraethylborate as reagent. The system was interfaced to an atomic absorption spectrometer and an atomic-fluorescence spectrometer to enable detection of the volatiles by these techniques. Optimization of AFS conditions, in particular purge gas flow rate, flame composition (H fuel gas flow rate) and reagent concentration, resulted in a detection limit of 20 ng/l. The method was applied to determination of Cd in three reference materials and in potable water; full test recoveries from potable water were 0.5-5 ng/ml. Citrate could be used to mask interference from some transition metals, e.g., Ni.
Cadmium Fluorescence Spectrophotometry Interferences Reference material Optimization Ultratrace

"Field Sampling Technique For The"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 3 Pages 281-285
Ben Fairman, Alfredo Sanz-Medel and Phil Jones

Abstract: Samples that contained 'fast reactive' Al (FR-Al), 0.01 M acetate buffer of pH 5 and 0.005 M 8-hydroxyquinoline (HQ) in acetate buffer of pH 5 were pumped simultaneously through a sampling manifold (illustrated). The sample and buffer were subsequently mixed in a reactor coil before the addition of the 0.005 M HQ and the combined streams passed through (2-5 min) a mini-column (5 cm x 1.5 mm i.d.) packed with Amberlite XAD-2 non-ionic resin. Retained Al was eluted with 330 µL 1 M HCl and analyzed by ICP-AES and ICP-MS (operating conditions tabulated). With ICP-AES the RSD was 8% for 2 mL samples of standard solutions that contained 100 µg/l of Al. The detection limit was 10 µg/l. FR-Al levels (40.6 ± 3.2 µg/l) in tap water (total Al 229 ± 10 µg/l) of pH 8.9 were in good agreement with HPLC analyzes at pH 3 (Jones, Int. J. Environ. Anal. Chem., 1991, 44, 1) for Al(III) (43.7 ± 2.1 µg/l). Problems were however encountered with moorland waters of pH 5.4-6.7 that contained less total Al and Al(III), due to the poor sensitivity levels of the ICP-AES detection system (discussed). Data from field sampling trials measured by ICP-MS were in good agreement with Al(III) levels (tabulated) measured by HPLC. The RSD was 8% for 2 mL samples of standard solutions that contained 100 µg/l of Al with a detection limit of 1.8 µg/l.
Aluminum(III) Aluminum, total Mass spectrometry Spectrophotometry Speciation 8-Hydroxyquinoline Amberlite Column

"Electrothermal Atomic Absorption Spectrometric Determination Of Molybdenum In Water, Human Hair And High-purity Reagents With Flow Injection Online Coprecipitation Preconcentration"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 8 Pages 533-537
Hengwu Chen, Shukun Xu and Zhaolun Fang

Abstract: Hair (0.1 g) was digested with 5 mL 70% HNO3 and 1 mL 70% HClO4 on a sand-bath at 120-150°C to near-dryness. After cooling, the residue was dissolved in 5 mL 4 M HCl and 5 mL Fe(II) solution (500 mg/l) containing 2% ascorbic acid (sufficient to reduce any trivalent Fe present) was added. The solution was diluted to 50 mL with water and portions were injected into a stream of 0.4 M HCl (1.7 ml/min) of a flow injection system (schematic shown) and mixed with a stream of 0.25% ammonium pyrrolidinedithiocarbamate solution (0.3 ml/min). The precipitate formed [Mo-Fe(II) pyrrolidinedithiocarbamate] was collected on the walls of a knitted reactor and dissolved in 50 µL MIBK. The MIBK concentrate zone was directly introduced into the GF (program details given) with Ar carrier gas (300 ml/min) and the absorbance was measured at 313.3 nm for Mo by AAS. The detection limits were 0.04 and 0.02 µg/l of Mo, respectively, for a 30 and 60 s loading times. RSD was 3.1% at 1.3 µg/l of Mo and recoveries of spiked Mo in tap water, seawater and sodium chloride reagent were 94-104%. Results obtained from the analysis of Mo in a human hair certified reference material agreed well with the certified value.
Molybdenum Spectrophotometry Coprecipitation MIBK Preconcentration Reference material Knotted reactor

"Kinetically Assisted Equilibrium Based Repetitive Determination Of Iron(II) With Ferrozine In Flow-through Systems"
Anal. Chem. 1976 Volume 48, Issue 8 Pages 1207-1211
V. V. S. Eswara Dutt, A. Eskander-Hanna, and Horacio A. Mottola

Abstract: Repetitive determination based on injection of the sample containing the sought-for species into a continuously circulated reagent mixture are described. Injection occurs directly into the detector chamber and the determination Is based on two consecutive processes: 1) a fast chemical reaction taking place in the detection zone, and 2) the washing out of the generated signal as a result of the Imposed flow. Practical application of the approach is illustrated with the determination of iron( It) in aqueous solutions utilizing the organic reagent Ferrozine. This method was applied to the determination of Iron In EPA Quality Control Water Samples, lake water, and tap water.
Iron(2+) Spectrophotometry Complexation Kinetic Closed loop

"Continuous-flow Cold Vapor Atomic Absorption Determination Of Mercury"
Anal. Chem. 1981 Volume 53, Issue 13 Pages 2030-2033
C. E. Oda and J. D. Ingle

Abstract: Three different designs for continuous flow reduction vessels are described for the determination of ultratrace concentrations of mercury. Sample and reducing solutions are continuously fed to the reduction vessels where the mercury is reduced and volatilized. The volatilized mercury Is swept into an absorption cell where the atomic absorption at 253.7 nm is measured. The best design is based on stripping of the mercury from a thin stream of solution with a countercurrent flow of gas over the solution stream. The detection limit for mercury Is 0.03 ppb.
Mercury Spectrophotometry

"Residual Ozone Determination By Flow Injection Analysis"
Anal. Chem. 1984 Volume 56, Issue 11 Pages 1973-1975
Michael R. Straka, Gilbert E. Pacey, and Gilbert Gordon

Abstract: For studies on the use of ozone as disinfectant for water, an automated method for the determination of residual ozone in water was required. By the optimization of the indigo blue method (cf. Bader and Hoigne, Ozone: Sci. Eng., 1982, 4, 169) for use with a flow injection analysis manifold, it was possible to analyze 120 samples h-1 with a 20-fold reduction in reagent consumption compared with the manual method (cf. loc. cit.). Interference from Cl and Mn is discussed.
Ozone Spectrophotometry Interferences Optimization Reagent consumption

"Simultaneous Flame Photometric Determination Of Lithium, Sodium, Potassium, And Calcium By Flow Injection Analysis With Gradient Scanning Standard Addition"
Anal. Chem. 1985 Volume 57, Issue 7 Pages 1457-1461
Zhaolun Fang, Joel M. Harris, Jaromir Ruzicka, and Elo H. Hansen

Abstract: A fast-scanning monochromator coupled to a digital oscilloscope was used to obtain analyte emission spectra (from 350 to 800 nm) from an air - acetylene flame. The method was applied to the determination of Na, K and Ca in 1 M ammonium acetate extracts of soil and in tap-water, the coefficient of variation for the metals being 3.9, 3.2 and 4.6%, respectively (n = 11). Addition of Li as an internal standard gave an improvement to 2.5% for Na but did not affect the coefficient of variation for the others. The results agreed closely with those obtained by a conventional flame-photometric method.
Sodium Potassium Calcium Spectrophotometry Gradient technique Internal standard Simultaneous analysis Standard additions calibration

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

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

"Flow Injection Donnan Dialysis Preconcentration Of Cations For Flame Atomic Absorption Spectrophotometry"
Anal. Chem. 1989 Volume 61, Issue 13 Pages 1410-1414
John A. Koropchak and Lori Allen

Abstract: The sample loop of a conventional HPLC injector was replaced by a coil of cation-exchange tubing, allowing Donnan dialysis to pre-concentrate cations before flame AAS determination. Nafion 811 (0.64 mm i.d.) was used, typically containing 0.5 M Sr(NO3)2 - 1.2 mM Al(NO3)3 - 0.1 M HNO3; the coil was lowered into the stirred sample solution for various times before introducing the receiver solution to the flame AAS instrument at optimum nebulizer flow rates. Enrichment factors of 100-fold were achieved. The method was applied in the determination of Pb in drinking water.
Cations Lead Spectrophotometry Donnan dialysis Nebulizer Preconcentration Optimization Nafion 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

"Flow Injection Analysis Of Organic And Inorganic Carbon In The Low-ppb Range"
Anal. Chem. 1991 Volume 63, Issue 19 Pages 2122-2130
Stefan A. Huber and Fritz H. Frimmel

Abstract: An improved form of the reactor of Graentzel (US Patent 420 19 17, May 6, 1980) in which acidification and UV irradiation, respectively, are used to convert inorganic and organic C to CO2, determined by IR spectrometry, is described (diagrams given) and shown to be useful as a LC detector. The constancy of all gaseous and liquid reactor in- and out-flows had been improved and a cooling device for the UV lamp (Graentzel, German Patent, DE 40 16 555 C1, Feb 19, 1991) had been installed. Calibration graphs were rectilinear for 4.5 to 770 µg L-1 of organic C as K hydrogen phthalate (coefficient of variation 0.4 to 19.7%, n = 4); the detection limit was 1.5 µg L-1 of organic C. The stability of the low organic C content solution, the liquid residence times, the elimination of inorganic C, the possibility of contamination by air and matrix effects were also studied. The reactor was also used to determine nicotinic and fulvic acids and pentachlorophenol and as a detector in the LC of tap water without pre-concentration.
Carbon LC Spectrophotometry PPB UV reactor Photochemistry

"Determination Of Chlorite And Chlorate In Chlorinated And Chloraminated Drinking Water By Flow Injection Analysis And Ion Chromatography"
Anal. Chem. 1992 Volume 64, Issue 5 Pages 496-502
Andrea M. Dietrich, Tracey D. Ledder, Daniel L. Gallagher, Margaret N. Grabeel, and Robert C. Hoehn

Abstract: The performance of flow injection analysis with iodometric detection (c.f., Miller, ibid., 1985, 57, 734) and ion chromatography with conductometric detection (c.f., Themelis, Anal. Chim. Acta, 1989, 225, 24) for the determination of chlorite and chlorate in drinking water was examined. The accuracy of both methods was similar, but the flow injection analysis method was affected by the presence of oxidants and chloramines; the ion chromatographic method was unaffected by the presence of such compounds. The addition of sodium oxalate and ethylenediamine to the drinking water increased the stability of chlorite to up to 3 and 18 days, respectively. Chlorate was stable in drinking water for up to 18 days, with or without preservative. The determination of CLO2- and ClO3- concentrations in drinking water by flow injection analysis (FIA) with iodometric detection and ion chromatography (IC) with conductivity detection was studied. The FIA and IC methods were accurate and effective for reagent water. The IC method was accurate for measurement of ClO2- and ClO3- concentrations in drinking water even in the presence of other oxidants including chloramines. However, FIA was affected by chloramines and other oxidants in drinking water, resulting in inaccurate determinations While ClO2- concentrations were unstable in chlorinated drinking water, addition of sodium oxalate increased the stability to 3 days and addition of ethylenediamine increased stability to 18 days. ClO3- concentrations were stable in drinking water for 18 days with or without a preservative.
Chlorate ion Chlorite HPIC Interferences Method comparison

"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

"High-precision Deuterium/hydrogen Measurement From Hydrogen Gas And Water By Continuous-flow Isotope Ratio Mass Spectrometry"
Anal. Chem. 1995 Volume 67, Issue 14 Pages 2486-2492
Herbert J. Tobias, Keith J. Goodman, Craig E. Blacken, and J. Thomas Brenna

Abstract: Water, injected into Ar (~15-20 cm/s), was passed through a GC coil at 210°C and subsequently through CuO/Pt at 850°C for combustion of organic species and through Ni at ~850°C to reduce water to H2. Any unreduced water was removed with a Nafion trap. H2 (m/z 2) and HD (m/z 3) were monitored simultaneously with a Finnigan MAT 252 MS instrument with multiple Faraday cup detectors, amplifiers and digitizers. Calibration graphs (peak height at ~300 mV) were linear for 1 x 10^-6 to 1 x 10^-2 parts of D2O in tap water. In a second procedure enriched H2 introduced into Ar (~50 cm/s) was brought into contact with a 99.9% Pd foil (0.125 in. diameter x 0.127 mm thick) held at ~330°C. Carrier gas and untransmitted H2 were permitted to flow to waste (illustrated). H2 and DH drawn through the Pd foil passed into the MS instrument via a cryotrap inserted to remove traces of water. The MS source chamber pressure was set at ~0.04 µTorr; other operating conditions were as for the Ar carrier system. Calibration graphs (peak height at ~300 mV) were linear.
Hydrogen-1 Hydrogen-2 Mass spectrometry Isotope ratio

"Titrimetry In A Continuous-flow System"
Fresenius J. Anal. Chem. 1978 Volume 293, Issue 5 Pages 413-415
H. F. R. Reijnders, J. J. van Staden and B. Griepink

Abstract: UFL
Sulfate Spectrophotometry Titrations

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

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

"Simultaneous Determination Of Sodium, Potassium, Magnesium And Calcium In Surface, Ground And Domestic Water By Flow Injection Analysis"
Fresenius J. Anal. Chem. 1980 Volume 302, Issue 5 Pages 370-374
Willem D. Basson and Jacobus F. Van Staden

Abstract: A simple, rapid, automated method is described for simultaneous determination of Na, K, Mg, and Ca in surface, ground, and domestic water, which is based on using the flow injection technique in combination with flame photometry and atomic absorption spectrophotometry. The method makes possible the anal. of ~128 samples/h with a coefficient of variation for Na <2.1%, for K <1.7%, for Ca <2.7%, and for Mg <1.8% (during 16 tests for each sample).
Sodium Potassium Magnesium Calcium Spectrophotometry Spectrophotometry Simultaneous analysis Automation

"Automated Turbidimetric Determination Of Sulfate In Surface, Ground And Domestic Water By Flow Injection Analysis"
Fresenius J. Anal. Chem. 1982 Volume 310, Issue 3-4 Pages 239-242
Jacobus F. van Staden

Abstract: A simple, modified, automated method for the turbidimetric determination of sulphate in surface, ground and domestic water, based on the principles of the flow-injection technique, is described. The one loop of a two-position sampling valve is used to sample an alkaline buffer-EDTA solution, alternated with water samples on the other loop. This ensures that the residual precipitate, coating the walls of the flowcell, is redissolved and the system kept clean. The method is suitable for the analysis of sulphate at a rate of up to 60 samples per hour with a coefficient of variation of better than 0.95 %.
Sulfate Turbidimetry

"Automated Prevalve Sample Filtration In Flow Injection Analysis. Determination Of Sulfate In Water Removing Suspended Solids And Color Before Sampling"
Fresenius J. Anal. Chem. 1982 Volume 312, Issue 5 Pages 438-440
Jacobus F. van Staden

Abstract: Suspended solids and the presence of organic substances and color are the main interferences in the turbidimetric spectrophotometric determination of sulphate at 420 nm in water. An automated flow-injection procedure is proposed in which these interferences are automatically removed by using an active carbon filter, which is incorporated in the flow system between the sampler and the sampling valve system. With this automated prevalve sample filter the proposed turbidimetric method gives the same results as a standard flow injection and an automated segmented method where the above mentioned interferences are manually removed prior to sampling. The method is applicable for the analysis of sulphate in surface, ground and domestic waters in the concentration range up to 200 mg/l at a sampling rate of up to 60 samples per hour with a coefficient of variation of better than 1%.
Sulfate Turbidimetry Filter Sample valve manipulation

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

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

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

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

"Automated Prevalve Dilution In Flow Injection Analysis. The Automated Determination Of Chloride In Surface, Ground And Domestic Water"
Fresenius J. Anal. Chem. 1985 Volume 322, Issue 1 Pages 36-41
Jacobus F. van Staden

Abstract: Surface, ground or domestic water was subjected to flow injection analysis. The sample was mixed with Fe(SCN)2+ and the absorbance was measured at 480 nm. The calibration graph was rectilinear for 120 mg L-1 of Cl- and the coefficient of variation were 1.16%.
Chloride Spectrophotometry

"Flow Injection Analysis Of Chloride In Tap And Sewage Water Using Ion-selective Electrode Detection"
Fresenius J. Anal. Chem. 1985 Volume 322, Issue 3 Pages 323-326
Liliana Ilcheva and Karl Cammann

Abstract: Tap-water or sewage water was analyzed by flow injection analysis with injection into the carrier stream (1.5 mL min-1) of 0.1 M KNO3, which flowed down a vertically suspended strip of filter-paper connected to a single-crystal AgCl membrane electrode and a double-junction reference electrode. Sixty samples h-1 could be analyzed and no serious interference was observed from S2-, I- or Br-. The limit of detection was 10 µM-Cl- and the coefficient of variation were 5 and 10% at >100 and 10 µM, respectively.
Chloride Electrode Electrode Interferences

"Potential Of Modified Reverse Flow Injection Analysis For Continuous Monitoring And Process Control"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 668-674
Wolfgang Frenzel

Abstract: The transient detector response observed after injection of standard solution into a continuously flowing sample stream is a measure of the concentration. of standard added to the continuous sample concentration. Calibration of the monitoring system is discussed and compared with that of other systems. Full details are given for application of the technique in the photometric determination of Cl- in tap water, PO43- in surface water and the potentiometric determination of F-, and each analysis is discussed.
Chloride Phosphate Fluoride Potentiometry Spectrophotometry Calibration Process control Reverse Theory

"Flow Injection Analysis With Electrochemical Detection"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 691-697
K. Cammann

Abstract: Two combinations of flow injection analysis with electrochemical detection are discussed. The use of potentiometry with ion-selective electrodes is illustrated by the determination of NO3- alone and simultaneously with Na+, K+, Ca(II), HCO3- and Cl- in drinking water, of Al without a reference electrode, of SO2 in grape juices, and of glucose in biological fluids. The apparatus is described and the experimental conditions are given. A hanging-mercury-drop electrode (at 0 V vs. Ag - AgCl) was used for the amperometric detection of ascorbic acid in a buffer (pH 4.7) stream.
Aluminum Ascorbic acid Glucose Nitrate Sulfur dioxide Amperometry Electrode Electrode Potentiometry Interferences Review

"Investigations On The Equivalence Of Analytical Procedures - Determination Of Chloride By Flow Injection Analysis And DIN Method In Water Analysis"
Fresenius J. Anal. Chem. 1989 Volume 334, Issue 1 Pages 9-12
G. Schulze, O. Elsholz, R. Hielscher, A. Rauth, S. Recknagel und A. Thiele

Abstract: Water was de-gassed and analyzed by one of the following methods. (i) A portion is injected into a stream of water, then mixed with a 15% methanolic solution of 2 mM Hg(SCN)2, 80 mM Fe(NO3)3 and 50 mM HNO3 and the absorbance is measured at 463 nm. (ii) A portion is injected into a stream of water, then mixed with 0.7 M Na acetate followed by 0.1 M Na acetate containing 1 mg mL-1 of Cl-. Detection is by means of tubular silver flow-through electrodes. (iii) A portion is injected into a stream of 2 M HNO3, this is mixed with a solution of 100 mg L-1 of AgNO3, the ppt. is filtered off and the filtrate is analyzed by AAS at 328.1 nm. The results obtained were reproducible and accurate and compared well with those obtained by the German standard (DIN) method. The methods developed were faster and more economic in the use of reagents than the standard method. For methods (i), (ii) and (iii), 120, 180 and 40 samples h-1, respectively, could be analyzed.
Chloride Spectrophotometry Spectrophotometry Electrode Precipitation Filter Standard method

"Application Of Flow Injection Potentiometry To The Determination Of Chloride In Various Matrices"
Fresenius J. Anal. Chem. 1989 Volume 335, Issue 8 Pages 931-937
Wolfgang Frenzel

Abstract: Chloride-selective electrodes were prepared from silver tubes (1 cm x 0.3 to 1.0 mm i.d.); the inner wall was coated with AgCl. Behaviour under steady-state and flow injection conditions was studied and the influence of system parameters on sensitivity, detection limit, response time and sample throughput was discussed. Sample throughput was 60 to 200 h-1. The calibration graph was rectilinear from 0.1 to 10,000 mg L-1 of Cl-, with a detection limit of 0.01 mg L-1 and a coefficient of variation of 1%. The method was applied in the analysis of tap and mineral water, emission control of HCl and the determination of Cl- in silicon nitride.
Chloride Electrode Electrode Potentiometry Sensitivity Detection limit Optimization

"Selective Spectrofluorimetric Determination Of Zinc In Biological Samples By Flow Injection Analysis (FIA)"
Fresenius J. Anal. Chem. 1992 Volume 342, Issue 7 Pages 597-600
P. Fern&aacute;ndez, C. P&eacute;rez Conde, A. Guti&eacute;rrez and C. C&aacute;mara

Abstract: Sample (0.25 g) was heated at 500°C for 2 h in a muffle furnace. The residue was dissolved in 0.5 mL of HNO3 and the solution was diluted to 25 mL with water. A 125 µL portion of the resulting solution was injected into a carrier stream (0.62 mL minmin1) of 0.5 M hexamethylenetetramine adjusted to pH 6 with HClO4 which merged with a stream (0.36 mL min-1) of 0.05% of 5,7-dibromo-8-quinolinol in ethyl ether. The two phases were separated and the organic phase was passed through a flow cell where its fluorescence was measured at 550 nm (excitation at 410 nm). The calibration graph was rectilinear up to 1 µg mL-1 of Zn(II); the detection limit was 3 ng mL-1. Sample throughput was 40 h-1. Among the 30 cations and anions studied, only Ni(II), Mn(II) and EDTA interfered seriously. The method was used to determine Zn in tap and well water, muscle, milk powder and whole diet. The automatization of a spectrofluorimetric method for the determination of zinc at trace level is described. It is based on the formation of the fluorescent complex Zn(II)-5,7-dibromo-8-quinolinol [Zn(II)-DBQ] followed by extraction into diethyl ether using flow injection analysis The optimum fluorescent emission is reached in hexamethylenetetramine (H2MTA+/HMTA) buffer pH 6.0. A membrane phase separator was used. The calibration graph is linear up to 1.5 µg/mL of Zn(II). The proposed method (detection limit 3 ng/mL) is very selective and has been successfully applied to determine Zn(II) in biological samples, tap waters, and various food items.
Zinc Fluorescence Organic phase detection Optimization Interferences Reference material Phase separator

"Online Sample Preparation And Determination Of Phenols With A Flow Analysis Method"
Fresenius J. Anal. Chem. 1992 Volume 342, Issue 4-5 Pages 426-428
C. Kwade Contact Information, R. Voigtl&auml;nder and K. Cammann

Abstract: A flow-analysis system has been developed to automate the phenol determination according to the German standard method DIN 38409-H16-2. The automation leads to a significant acceleration of the procedure. One analysis only lasts 3 min while the complete manual determination requires 3 h. Also the sample, solvent and reagent volumes are reduced to a tenth of the volumes demanded by the standard method. The described phenol determination is based on the integration of an air segmented ('Airsegmented-Flow-Analysis' SFA) part in a flow injection analysis (FIA) system. The main steps of the analytical procedure are: Reproducible inserting of the sample in a carrier stream, sample pretreatment and sample measuring. In the first step the sample is injected into the carrier stream. It transports the sample in the reaction coil and than through the distillation unit. The steam distillation represents the sample preparation step; therefore an air segmented stream is necessary. Afterwards the different phases (liquid and gas) were singled again and the distilled solution is fed into the FIA manifold. The determination itself takes place inside the FIA system. The limit of determination amounts to 0.01 mg L-1 with a standard deviation of 1.5%. Different waste, surface and drinking water samples have been analyzed without any problems. The results correspond very well to those obtained by manual procedure.
Phenols Spectrophotometry Standard method Segmented flow Method comparison

"Online Trace Preconcentration - Matrix Separation By High Performance Flow Atomic Spectrometry (HPF-flame AAS). Trace Determination In Aluminum And In Drinking Water"
Fresenius J. Anal. Chem. 1993 Volume 346, Issue 6-9 Pages 711-716
H. Berndt, A. M&uuml;ller and G. Schaldach

Abstract: A 20 mL portion of aluminum chloride solution (20 g/l) was treated with 0.2 mL of methanolic 0.5% ammonium pyrrolidine-1-carbodithioate solution of pH 3. Portions of the resulting solution (1 ml) were injected into a carrier stream of 0.1 M HNO3. The complexes formed were separated by passing through a 5-mm column of Nucleosil 100 C18 or ODS Hypersil (5 µm); elution was effected by reversed-flow with methanolic 10 mM HNO3. Metals in the eluate were determined by AAS with hydraulic high-pressure nebulization. The combined effects of pre-concentration. and the aerosol generation improved the detection limits by factors of up to 50 for 10 elements; the range was 0.1-1 ppm with analysis times 3 min. Water (90 ml) was mixed with 0.2% quinolin-8-ol solution in 1 M acetic acid (0.2 ml) and aqueous 2 M NH3 (0.4 ml), and further sample was added to a total volume of 100 mL. Portions were analyzed as above with water as the carrier stream. The improvement in detection limits was up to 90-fold for eight elements. Results for three water samples were comparable with those obtained by graphite-furnace AAS.
Aluminum Spectrophotometry Preconcentration Method comparison 8-Hydroxyquinoline

"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

"Analytical Possibilities Of Microelectrode Use For Stripping Voltammetry"
Fresenius J. Anal. Chem. 1994 Volume 349, Issue 8-9 Pages 646-649
Frank-Michael Matysik Contact Information, Petra Gl&auml;ser and Gerhard Werner

Abstract: A microelectrode capillary flow injection system (cf Matysik and Werner, Analyst (London), 1993, 118, 1523) was used to determine Pb2+ in 1.3 µL of water giving a linear calibration range of 10^-95 µg/l, a detection limit of 6 µg/l, and an RSD (n = 8) for 20 µg/l of Pb2+ of 3.2%. The use of hemispherical or disc Pt/Hg electrodes in anodic differential pulse stripping-voltammetric determination of 1 mg/l of Pb2+ in 1 mM HNO3 with deposition for 2 min at -1 V vs. Ag/AgCl, scan rate 10 mV/s and pulse amplitude 40 mV was studied. For 25-60 µm diameter disc micro-electrodes the RSD obtained without stirring during accumulation (0.38-0.76%) were lower than those obtained with stirring at 1000 or 2000 rpm (0.72-1.67%). The peak heights obtained using quiescent accumulation were significantly less than those obtained with stirring for larger electrodes but for micro-electrodes with diameter 30 µm these peak height differences were slight. The use of micro-electrodes to determine low µg/l levels of Cu2+ in whisky and Cd2+ and Pb2+ in drinking water is also described.
Cadmium(2+) Copper(II) Lead(2+) Voltammetry Electrode

"Advances In Photolithographically Fabricated ENFET Membranes"
Fresenius J. Anal. Chem. 1994 Volume 349, Issue 8-9 Pages 666-669
Astrid Z&uuml;rn, Beatrice Rabolt, Manfred Gr&auml;fe and Helmut M&uuml;ller

Abstract: ENFET (enzyme FET) biosensors were constructed by coating an n-channel depletion mode ISFET (1.2 x 4.2 mm) with a solution of acrylamide, Michler's ketone, benzophenone, bisacrylamide and urease in aqueous 50% ethanol. The coated chip, which contained two ISFET gates (16 x 400 µm) with SiO2/Si3N4 gate insulator, was exposed to UV radiation through a mask and the crosslinked membrane was developed by washing with water. When used in a flow injection system a biosensor obtained from a coating solution containing 40 mg/ml of urease showed a high sensitivity to urea with a linear calibration range from 1-500 mM and a response time (95%) of 20 s. The response was not inhibited by exposure for 5 min to 10 mg/l of Cu(II) at 1.8 ml/min. The biosensors were stable for 30 days either dry or immersed in buffer solution. Compounds present in serum or waste water from urea production did not interfere. Biosensors obtained from coating solution containing 7 mg/ml of urease were used to detect pesticides, e.g., down to 0.1 µg/l of Carbofuran, by monitoring the inhibition by the pesticides of the biosensor urea response. These biosensors should be useful in screening for pesticides in drinking water.
Urea Pesticides Sensor Spectrophotometry Field effect transistor Interferences

"Gran's Plot Titration And Flow Injection Titration Of Sulfate In Ground And Drinking Water With A Barium Ion-selective Electrode"
Fresenius J. Anal. Chem. 1994 Volume 350, Issue 10-11 Pages 630-632
O. Lutze, B. Ro&szlig; and K. Cammann

Abstract: The application of a barium ion-selective electrode for the determination of sulfate is reported. Titrations in the batch mode using the Gran's plot method [1] have been carried out. In the presence of a lithium acetate buffer and after the addition of isopropanol it has been possible to determine sulfate with a relative standard deviation (RSD) of 1.5%. The concentration range of the samples was 5-400 mg sulfate/l. Interfering ions were separated by cation-exchange. This indirect titration constituted the basis of a flow injection titration (FIA titration) system for the continuous determination of sulfate. By plotting the peakwidth vs. the logarithm of the sulfate concentration of the injected samples, linear calibration graphs in the range of 50-200 mg sulfate/l were obtained. In this system, the sample stream was pumped through an ion-exchange column, mixed with a buffer stream of lithium acetate and injected in a reagent stream of a BaCl2 solution. The resulting free Ba(II) concentration was monitored with a barium ion-selective electrode. The content of sulfate in ground and drinking water samples has been determined with a RSD between 1.2% and 1.3%.
Sulfate Electrode Indirect Precipitation Titrations

"Flow Injection Spectrophotometric Determination Of Residual Free Chlorine And Chloramine"
Fresenius J. Anal. Chem. 1995 Volume 351, Issue 2-3 Pages 335-337
Anupama Chaurasia and Krishna K. Verma

Abstract: Reagent (2,4-dinitrophenylhydrazine in H2SO4 and HCl or acetic acid; preparation details given) was injected into a carrier stream (0.36 ml/min) of 0.2 M KCl adjusted to pH 1 with 0.2 M HCl and the carrier stream merged with the sample stream (0.93 ml/min). The merged stream passed through a reaction coil (105 cm x 0.5 mm i.d.) and the absorbance was measured at 360 nm. Beer's law was obeyed for 0.1-10 mg/l chlorine with a detection limit of 0.05 mg/l. The effects of foreign ions are tabulated. The method was applied to the analysis of natural and drinking water with RSD of 2.3% for chlorine and chloramine.
Chlorine, residual, free Chloramide Spectrophotometry Interferences Speciation

"Kinetic Flow Injection Spectrofluorimetric Determination Of Aluminum(III) Using Eriochrome Red B, Sensitized By Traces Of Fluoride"
Fresenius J. Anal. Chem. 1996 Volume 354, Issue 2 Pages 204-207
F. Carrillo, C. P&eacute;rez-Conde, C. C&aacute;mara

Abstract: Samples (100 µL) containing 1000 µg/l Al were injected into a carrier stream of 0.01 M NaF (0.45 ml/min) and mixed with 1.5 M hexamethylenetetramine (HMTA) buffer of pH 6 in a stream of HClO4 (0.6 ml/min) in a reaction coil (50 cm). The mixed solution was subsequently mixed with a 0.1% Erichrome Red B solution (0.45 ml/min) in a second reaction coil (500 cm x 0.5 mm i.d.) at 80°C and cooled to 4°C in a third reaction coil. The fluorescence intensity of the resultant solution was measured in a 18 µL flow cell (10 mm light-path) at 595 nm (excitation at 470 nm). The calibration graph was linear up to 1000 µg/l of Al with RSD (n = 10) of 2.6, 2.2 and 2%, respectively, for 5, 20 and 50 µg/l of Al, respectively. The detection limit was 0.15 µg/l in the presence of fluoride. Potential interferent anions and cations (listed) were studied with 20 µg/l Al; FIA was more selective than a batch procedure and more tolerant of Fe(III). The procedure was used successfully to determine Al in tap water, mineral water or urine.
Aluminum(III) Fluorescence Interferences Kinetic

"Determination Of Zinc By Flow Injection With Fluorimetric Detection In A Micellar Medium"
Fresenius J. Anal. Chem. 1996 Volume 355, Issue 1 Pages 88-91
N. Ga&ntilde;&aacute;n Guti&eacute;rrez, F. S&aacute;nchez Rojas and J. M. Cano Pav&oacute;n

Abstract: Sample was injected into a carrier stream (1.9 ml/min) of 0.02 M acetate buffer of pH 5, the carrier stream merged with a 3% Triton X-100 stream (1.9 ml/min) and the solutions were mixed in a mixing coil (150 cm x 0.5 mm i.d.). The resulting stream merged with a reagent stream (1.2 ml/min) of 5 mM salicylaldehyde thiocarbohydrazone in DMF, passed through a mixing coil (200 cm x 0.5 mm i.d.) and the fluorescent intensity was monitored at 462 nm (excitation at 410 nm). Calibration graphs were linear for 10^-1000 ng/ml of Zn with a detection limit of 5 ng/ml and a RSD (n = 10) of 1.8 and 2% for 50 ng/ml and 100 ng/ml Zn, respectively. The effects of foreign ions are discussed. The method was applied to the determination of Zn in drinking water and biological materials.
Zinc Fluorescence Triton X Micelle Surfactant

"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 Mini Column Technique With ICP-AES Detection For The Isolation And Preconcentration Of The Fast Reactive Aluminum Fraction In Waters"
Fresenius J. Anal. Chem. 1996 Volume 355, Issue 7-8 Pages 757-762
Ben Fairman and Alfredo Sanz-Medel

Abstract: A 1 mL sample was injected into water at a flow rate of 0.6 ml/min which was then mixed with 0.03 M sodium acetate/acetic acid buffer of pH 5 (buffer A) at a flow rate of 0.27 ml/min. Simultaneously, 1.5 mL of 0.5 mM 8-hydroxyquinoline (oxine) in 0.1 M buffer A was injected into water at a flow rate of 1.2 ml/min. After merging, the two streams were passed through a reaction coil (0.5 m long) then applied to a column (5 x 0.3 cm) of Amberlite XAD (0.08-0.16 mm). The oxine complexes of fast-reactive Al were backflushed from the column with water at a flow rate of 1.2 ml/min containing 0.3 mL 1 M HCl. Detection was by ICP-AES at 396.15 nm. Calibration graphs were linear up to 200 and 500 µg/l of fast-reactive Al with one and two HCl backflushes, respectively. The detection limit was 2 µg/l fast-reactive Al and up to 18-fold pre-concentration was possible. Injected samples with high organic C content may be passed through an XAD column in order to remove the organic compounds. The method was applied to tap water and a solution with an F- to Al3+ mol. ratio of 0.27:1 gave results comparable with those obtained by HPLC. The possibility of using the method for field sampling is discussed.
Aluminum Spectrophotometry Preconcentration 8-Hydroxyquinoline Amberlite

"Determination Of Mercury(II) Traces In Drinking Water By Inhibition Of An Urease Reactor In A Flow Injection Analysis (FIA) System"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 6 Pages 752-755
Renbing Shi, K. Stein, Georg Schwedt

Abstract: The immobilization of urease on to polyacrylamide gel was carried out by a modification of a previous method (Stein and Schwedt, Vom Vasser, 1992, 79, 211). Acrylamide (50 mg) with 5% NN'-methylene bisacrylamide was dissolved in 0.5 mL phosphate buffer of pH 7 then 330 iu urease was dissolved in the resultant solution. Then 7 µL NNN'N'-tetramethylene diamine/ammonium peroxodisulfate (2:5) was added. This reaction mixture was poured on to a cellulose acetate membrane between two glass plates. After 30 min, the plates were separated and the enzymatic membrane was cut into pieces (1 cm diameter). A piece of membrane was rolled up and set in a glass column (45 x 2 mm i.d.). This urease reactor was integrated into an FIA system (schematic and details given). The measurement parameters are tabulated. Potentiometric measurements were made using an Ingold LOT 453 S-7 pH electrode. Calibration graphs were linear from 2-20 µg/l Hg(II); RSD was 1.4% (n = 5) for 2 µg/l Hg(II). A sample frequency of 7/h was achieved. The method was applied to the analysis of potable water; results were comparable with those obtained by a commercial system.
Mercury(II) Potentiometry Electrode Immobilized enzyme Method comparison Membrane Cellulose acetate

"Flow Injection Atomic Absorption Spectrometry For The Standardization Of Arsenic, Lead And Mercury In Environmental And Biological Standard Reference Materials"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 7 Pages 827-832
Gautam Samanta and D. Chakraborti

Abstract: Environmental and biological CRM were digested (details given). For the determination of Pb, prepared samples (50 µL) were injected into a carrier stream (1 ml/min) of 9% ammonium persulfate in 6% HNO3, which merged with a reducing stream (1 ml/min) of 8% NaBH4 in 1% NaOH then passed through a gas-liquid separator. A N2 flow (100 ml/min) carried hydrides to an AAS instrument for determination at 283.3 nm using an air-acetylene flame. For the determination of As, the carrier stream was 5 M HCl, the reducing stream was 1% NaBH4 containing 0.5% NaOH, the N2 flow rate was 200 ml/min and measurement was at 193.7 nm. For the determination of Hg, the carrier stream was 4% NaOH, the reducing stream was 0.5% SnCl2 and 0.035% L-cysteine in 1.5% H2SO4, the N2 flow rate was 50 ml/min and measurement was at 253.7 nm. A flame was not required for Hg determinations. The detection limits were 2 µg/l Pb, 1.8 µg/l As and 1.5 µg/l Hg, the quantitation limits were 7, 6 and 5 µg/l, respectively, and the corresponding RSD (n = 10) were 4%, 3% and 2%. Calibration ranges and recoveries are not stated. The sample throughput was 80/h in all cases. Results are tabulated for 12 CRM. The effects of interferents are also discussed. Results of a thorough study and application of flow injection atomic absorption spectrometry for the determination of As, Pb and Hg in parts per million to subparts per billion levels in environmental and biological samples have been described. Various standard reference materials from the National Bureau of Standards, USA, the National Institute of Standards and Technology, USA, the Community Bureau of Reference, Brussels, Belgium and the National Institute for Environmental Studies, Japan and Standard Chinese river sediment were used. By flow injection hydride generation AAS the standard reference materials were analyzed for As and Pb. Mercury was determined by cold vapor flow injection AAS from environmental and biological standard reference materials. The technique is fast, simple and highly sensitive. It takes only 30 s for each analysis from the digested solution. The detection limits of As, Pb and Hg are 1.8 µg L-1, 2.0 µg L-1 and 1.5 µg L-1, respectively. The results show good agreement with the certified values. 48 References
Arsenic Lead Mercury Spectrophotometry Sample preparation Spectrophotometry Reference material Interferences PPB Volatile generation Volatile generation

"Gaseous Sample Introduction For The Determination Of Silicon By ICP-AES"
Fresenius J. Anal. Chem. 1997 Volume 358, Issue 5 Pages 599-603
A. Lopez Molinero, Alberto Morales, Anselmo Villareal, Juan R. Castillo

Abstract: A portion (150 µL) of Si solution was injected into a stream (1 ml/min) of 0.05 M NaF solution, which passed through a 5 cm mixing coil and a 25 cm reaction coil prior to nebulization. A portion (100 µL) of H2SO4 was injected into the flow 15 s after the injection of the Si solution; the second injector was positioned between the mixing and reaction coils. Nebulization was with Ar (1.3 l/min) and detection was by ICP-AES at 251.611 nm (instrumental settings given). The calibration graph was linear from 0.1-200 µg/ml Si, the detection limit was 4 ng/ml and the RSD was 2%. Alternatively, a portion (150 µL) of Si solution was injected into a stream (1 ml/min) of 0.01 M NaF, which passed through a 25 cm mixing coil and into a nebulization chamber via a Meinhard nebulizer with Ar as nebulization gas (500 ml/min). Simultaneously, a portion (100 µL) of H2SO4 was injected into a separate flow (1 ml/min) of 0.01 M NaF, which passed through a 25 cm mixing coil and into the same nebulization chamber via a cross-flow nebulizer with Ar at 1 l/min. The aerosols reacted in the chamber and passed into the ICP for detection as described above. The calibration graph was linear from 0.1-1000 µg/ml Si, the detection limit was 20 ng/ml and the RSD (n = 6) was 8%. The methods were applied to mineral- and tap water (results presented).
Silicon Spectrophotometry Gas phase reaction

"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

"Fluorimetric Determination Of Bromate By Ion-exchange Separation And Post-column Derivatization"
Microchim. Acta 1998 Volume 129, Issue 3-4 Pages 281-290
Achim Gahr, Norbert Huber and Reinhard Niessner

Abstract: A method for the determination of bromate in drinking water based on a stopped-flow post-column reaction after anion-exchange separation was developed. Sample (100 l) was subjected to ion exchange on an IonPac AS4A column without a guard column with 10 mM boric acid eluent of pH 9.3 (1.75 ml/min). After separation, the sample zone was mixed in a T-piece with the azo dye sulfonaphtholazoresorcinol (SNAR) in sodium bromide in HClO4. The sample zone was then disconnected from the carrier via a 6-port by-pass switch (stop-phase). The sample zone was then inserted into the main stream and mixed (flow-phase) with gallium nitrate. The residual SNAR was quantitatively converted to a fluorescent binuclear complex. The fluorescence was recorded continuously at 585 nm (excitation at 521 nm). The determination was based on the decrease in fluorescence intensity with increasing bromate concentration. The method was linear up to 15 g/l with a detection limit of 0.28 g/l of bromate.
Bromate HPIC Ion exchange Fluorescence Post-column derivatization

"Spectrophotometric Determination Of Carbaryl By Flow Injection Analysis"
Microchem. J. 1988 Volume 38, Issue 3 Pages 370-375
P. Y&aacute;&ntilde;ez-Sede&ntilde;o, C. Nova Nova and L. M. Polo D&iacute;ez*

Abstract: Sample solution (120 µL) was injected into the carrier stream (0.4% NaNO2) which was then mixed with 0.5% sulfanilic acid in a reaction coil (12 cm x 0.5 mm) before passing to a second coil (1.5 m x 0.8 mm) to be mixed with 0.4 M NaOH. The absorbance of the solution was measured at 515 nm. Carbaryl(I) was extracted from formulations with ethanol for 30 min, and a 5 mL portion of ethanolic extract was diluted to 500 mL before injection as above. To determine I in potable water, 20% H2SO4 was added to a 250 mL sample (to pH 5), 2.5 g of anhydrous Na2SO4 was dissolved in the solution, 35 mL of CH2Cl2 was added, the solution was shaken, and the aqueous phase was re-extracted with CH2Cl2 (25 ml). The organic extract was washed, dried on a column of Na2SO4, then evaporated to dryness, and the residue was dissolved in 25 mL of 1% ethanol for analysis as before. Calibration graphs were rectilinear over the ranges 10 to 40, 1 to 10 and 0.1 to 1 ppm of I, and the detection limit was 0.08 ppm. The coefficient of variation was 3.8% at the 0.5 ppm level. Recoveries were quantitative.
Carbaryl Spectrophotometry Calibration Optimization

"Flow Injection Spectrophotometric Determination Of Free Residual Chloride In Waters With 3,3'-dimethylnaphtidine"
Microchem. J. 1995 Volume 51, Issue 3 Pages 379-386
Pobozy E., Pyrzynska K., Szostek B. and Trojanowicz M.

Abstract: Water samples (200 µL) were injected into a carrier stream (2.2 cm/min) of water which merged with a stream (2.2 cm/min) of aqueous 0.002% 3,3-dimethylnaphtidine and passed through a reaction coil (50 cm x 0.5 mm i.d.) before detection of the oxidation product at 535 nm. The detection limit for Cl was 30 µg/l and the calibration graph was linear for 0.1-1 mg/l of Cl; the RSD (n = 10) at 0.4 mg/l Cl was 1.2% and the day-to-day RSD were 3%. Sample throughput was 150/h. Chloride, sulfate, nitrate, Fe(III), sulfite, nitrite, chromate, Cu(II), Mn(II) and Ca and Mg salts did not interfere. The results for tap and swimming pool water agreed well with those obtained by the standard NN-diethyl-p-phenylenediamine method.
Chloride, free Spectrophotometry Method comparison Interferences

"Studies On The Synergic Effects Of Metal Cations On Kinetic Reactions And Their Analytical Applications"
Microchem. J. 1996 Volume 53, Issue 3 Pages 376-384
Jianhua Wang and Ronghuan He

Abstract: The mutual catalytic (synergic) effect between closely related metal cations such as Mo(VI) and W(VI), Ag(I) and Hg(II) and Fe(II) and Sb(III) on different kinetic reaction systems viz. Cr(VI)/iodide, H2O2/iodide and thiourea activated hexacyanoferrate (II)-α,α-bipyridyl, respectively, was studied spectrophotometrically with a stopped-flow-FIA technique. A synergic catalytic coefficient (D) was defined and a method for the simultaneous determination of the components in binary mixtures was proposed (theory and details given) by introducing the coefficient D into the reaction systems to compensate for the deviations of absorbance from additivity. Portions of standard metal ion solutions were injected into a carrier stream of an FIA manifold (schematic shown) and mixed with reagent streams at 3 ml/min in a reaction coil (250 mm) [experimental details given]. The colored complex formed was detected by the method of Wang and He spectrophotometrically. (Anal. Chim., 1993, 276, 419). Under optimized conditions (tabulated), calibration graphs were linear up to 3.7, 3.5, 1.1 and 2 µg/ml, respectively, for Sb(III), Fe(II), Mo(VI) and W(VI) and up to 210 and 195 ng/ml, respectively, for Hg(II) and Ag(I). The method was applied to the analysis of Mo and W in steel, Fe(II) and Sb in a zinc standard and Hg and Ag in tap water. Results agreed well with listed values.
Antimony(3+) Iron(2+) Molybdenum(VI) Tungsten(VI) Mercury(II) Silver(I) Spectrophotometry Kinetic Stopped-flow Optimization

"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

"Rapid Determination Of Fluoride In Potable Waters By Potentiometric Flow Injection Analysis"
Anal. Lett. 1986 Volume 19, Issue 13&14 Pages 1387-1406
Davey, D.E.;Mulcahy, D.E.;O'Connell, G.R.

Abstract: A potentiometric flow injection analysis system is described (with schematic diagrams) for the analysis of 360 samples h-1 by using a F--selective electrode polished with slurried alumina. Factors discussed include the detector cell design, carrier stream composition, flow rate and sample loop volume The use of unresponsive F--selective electrodes, regenerated by using a silver epoxy - AgF technique, was also evaluated. Calibration graphs were curvilinear from 20 to 200 µM-F- at sampling rates of 240 and 360 h-1. The method has been used for the analysis of tap water.
Fluoride Electrode Potentiometry

"Determination Of Trace Amounts Of Phosphate In Natural Water By Flow Injection Fluorimetry"
Anal. Lett. 1989 Volume 22, Issue 15 Pages 3081-3090
Wei, F.;Wu, Z.;Ten, E.

Abstract: Sample (50 µL) is injected into a carrier stream of water which then merges with merged streams fo 28 mM Mo(VI) - 0.8 M HCl and 20 µM-rhodamine 6G (C. I. Basic Red 1) - 0.025% of OP, and after passage through an 88-cm mixing coil the degree of fluorescence quenching at 550 nm is measured (excitation at 350 nm). The calibration graph is rectilinear for 100 ng mL-1 of P, and the detection limit is 2 ng mL-1. Only As(V) interferes, but can be masked by a 50-fold concentration. of S2O32-. Coefficients of variation (n = 12) for 10, 20 and 50 ng mL-1 of P were 5.4, 1.8 and 1.1%, respectively, and recoveries from tap-, well-, lake and pond water ranged from 92 to 102%.
Phosphate Fluorescence Quenching Interferences

"Piezoelectric Quartz Crystal Biosensor As A Direct Affinity Sensor"
Anal. Lett. 1994 Volume 27, Issue 8 Pages 1475-1487
Minunni, M.;Skladal, P.;Mascini, M.

Abstract: AT-cut piezoelectric quartz crystals with a basic resonant frequency of 10 MHz were fixed inside a flow-through thin-layer cell (30 µL) with one electrode in contact with the flowing liquid (70 µL/min); the crystal electrodes were connected to the detector (PZ 106; Universal Sensors, New Orleans, LA, USA). Adsorption of human IgG onto the Au electrode of the crystal was investigated. Measurements were performed in the continuous-flow mode using electrodes that had been treated sequentially with 1.2N-NaOH (20 min), water, 1.2N-HCl (5 min), concentrated HCl (2 min), then washed and dried in air. A graph of resonant frequency shifts for protein concentrations of 1 µg/ml to 10 mg/ml is shown; the analysis time was 5 h. The binding of mAb to 2,4-dichlorophenoxyacetic acid (2,4-D) immobilized onto the electrodes was also studied. The 2,4-D was activated with tributylamine and isobutylchloroformiate in dioxane, and immobilized with BSA onto γ-aminopropyltriethoxysilane-treated electrodes using glutaraldehyde (details given). The affinity reacton occurred in 10 min. A similar method was applied to determine 2,4-D in tap water.
Immunoglobulin G 2,4-dichlorophenoxyacetic acid Electrode Sensor

"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

"Flow Injection Chemiluminescence Sensor For The Determination Of Free Chlorine In Tap Water"
Anal. Lett. 1997 Volume 30, Issue 1 Pages 11-19
Wei Qin; Zhujun Zhang; Shuna Liu

Abstract: A schematic diagram is given of the flow system. Luminol was immobilized on an anion-exchange column. A 0.15 M NaOH (200 µL) stream was mixed with a water carrier stream and injected via a six-way valve into the anion-exchange column. The alkaline aqueous solution eluted luminol from the column which was then mixed with a sample stream which had already passed through a cation-exchange column to remove interfering metal ions. The streams were mixed just before the flow cell and the resulting chemiluminescence was measured. The response of the sensor was linear from 10 ng/l to 40 µg/l with a detection limit of 8 ng/ml. The sample throughput was 60/h. The RSD (n = 7) was The effects of foreign ions on the determination were investigated. Recoveries ranged from 95-106%.
Chlorine, free Chemiluminescence Ion exchange Sensor Immobilized reagent Resin Interferences

"Amperometric Immunosensor For The Detection Of 2,4-dichlorophenoxyacetic Acid (2,4-D) In Water"
Anal. Lett. 1997 Volume 30, Issue 3 Pages 515-525
M. Wilmer; D. Trau; R. Renneberg; F. Spener

Abstract: An amperometric immunosensor for the determination of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) in water has been developed using sequential injection analysis techniques. The system is based on a rapid competitive enzyme immunoassay employing an alkaline phosphatase-labeled monoclonal antibody directed against the herbicide and an immunoreactor with 2,4-D immobilized via bovine serum albumin either to Eupergit in a column or directly to the surface of a glass capillary. The detection limit of the immunosensor at 0.1 µg 2,4-D/L without enrichment of the analyte makes automatic measurements of 2,4-D in drinking and groundwater feasible.
2,4-dichlorophenoxyacetic acid Endothall sodium Amperometry Sequential injection

"An Extrapolation Method For The Fast Evaluation Of The Fluoride Ion-selective Electrode Equilibrium Potential In Continuous-flow Analysis"
Electroanalysis 1995 Volume 7, Issue 3 Pages 221-224
Xue D. Wang, Wei Shen, Robert W. Cattrall, Graeme L. Nyberg, John Liesegang

Abstract: The fluoride ion-selective electrode has been used in continuous flow analysis to determine the fluoride concentration in aqueous solution. The varying electrode potentials, E(t), were collected in the first 60 s by an interfacing computer, and the equilibrium potential of the electrode was predicted using an extrapolation method. This value agrees to within ±0.5 mV of the comparative value obtained by allowing sufficient time for the electrode to reach a steady state. Like flow-injection (FI), continuous flow (CF) analysis with this extrapolation method significantly shortens the time required for routine fluoride concentration measurements, but it also achieves a higher sensitivity than FI. The method has been applied to the determination of fluoride in city tap water.
Fluoride Electrode Extrapolation method

"Simultaneous Determination Of Chloride And Fluoride Ions In Waters By Sequential Injection Analysis"
Electroanalysis 1996 Volume 8, Issue 11 Pages 1051-1054
Jes&uacute;s Alp&iacute;zar, Antonio Cresp&iacute;, Andreu Cladera, Rafael Forteza, V&iacute;ctor Cerd&agrave;

Abstract: A sequential injection analysis (SIA) system was developed, based on chloride (I)-selective and fluoride (II)-selective electrodes placed in series, in conjunction with a Ag/AgCl reference electrode (diagram given). Water samples (0.2 ml) were subjected to SIA, sandwiched between 0.4 mL and 3.8 mL cyclohexane-1,2-diamine-NNN'N'-tetra-acetic acid as total ionic strength adjustment buffer, at a flow-rate of 4 ml/min and with potentiometric detection. Calibration graphs were linear from 20-500 µg/ml I and 0.5-200 µg/ml II. The RSD (n = 20) were 1% for 50 µg/ml I and 3.7% for 1 µg/ml II. Stopped-flow detection did not improve the results. The method was applied to potable water samples. The I results generally agreed with those obtained using a batch method and the Mohr method. Recoveries of II from spiked tap water were 92-109%.
Chloride Fluoride Potentiometry Electrode Electrode Electrode Sequential injection Method comparison Stopped-flow

"Polar, Hydrophilic Compounds In Drinking Water Produced From Surface Water. Determination By Liquid Chromatography - Mass Spectrometry"
J. Chromatogr. A 1991 Volume 554, Issue 1-2 Pages 251-266
H. Fr. Schr&ouml;der

Abstract: Samples from waste water treatment-plants, surface waters and drinking water treatment plants were solid-phase extracted (details given) and the cited compounds were detected and identified by LC - tandem MS coupled online by a thermospray interface (details given). After identification, quantification by direct mixture analysis by the system without derivatization and separation, was possible with the availability of standards and with use of flow-injection analysis (details given). Use of GC - MS (described) was only useful for detection of volatile compounds.
Organics, polar LC Mass spectrometry Sample preparation Extraction Interface

"Pollutants In Drinking Water And Waste Water"
J. Chromatogr. A 1993 Volume 643, Issue 1-2 Pages 145-161
Horst Fr. Schr&ouml;der

Abstract: Pollutants in drinking and waste water from treatment plants were extracted using either continuous liquid-liquid or solid-phase extraction (no details given) and analyzed by GC on a fused-silica column (30 m x 0.32 mm) coated with DB-1701 (0.25 µm) with He as carrier gas (15 cm/s) or by HPLC on a column (30 cm x 3.9 mm) of µBondapak C18 (5 µm) or a column (25 cm x 4.6 mm) of Hyperchrome NC NH2 (5 µm) with various mobile phases (details given). Pollutants were detected by MS, MS-MS and UV systems using EI, thermospray and discharge ionization techniques. Difficulties encountered in detecting the surface-active compounds present in water samples may be reduced by using soft ionization techniques, flow injection analysis and collision-induced dissociation combined with MS-MS to achieve definite identification of these polar compounds. Extracts of drinking water and effluents from municipal and industrial sewage treatment plants were analyzed by gas chromatography-mass spectrometry and by high performance liquid chromatography combined with ultraviolet and/or mass spectrometric detection. After column chromatography or flow injection analysis bypassing the analytical column, ionization was performed by a thermospray interface. Identification of the pollutants was carried out by tandem mass spectrometry, generating daughter-ion spectra by collision-induced dissociation. Most pollutants in drinking water and in the effluents of waste water treatment plants are surface-active compounds of anthropogenic origin or their biochemical degradation products. Difficulties encountered during separation, detection and identification are presented and discussed and techniques for solving these problems are proposed.
GC Mass spectrometry Spectrophotometry

"Determination Of Pesticides In Drinking Water By Online Solid-phase Disk Extraction Followed By Various Liquid Chromatographic Systems"
J. Chromatogr. A 1993 Volume 645, Issue 1 Pages 125-134
Serge Chiron and Damia Barcel&oacute;

Abstract: Drinking water containing aldicarb (I), carbofuran (II), carbaryl (III), chlortoluron, isoproturon and metolachlor at 0.2 and 5 µL/l were concentrated on C-18 Empore extraction discs, then desorbed and separated on Supersphere 60 RP-8 (4 µm) in a LiChrocart cartridge column (25 cm x 4.6 mm) with gradient elution (0.8 µL/min) of acetonitrile/methanol/H2O and aqueous acetonitrile (details given) with UV detection at 220 nm. Recoveries were dependent on pesticide level and pre-concentration. water volume (50-1000 ml). The detection limits were 0.01-0.03 µg/l. Lower detection limits for I, II, III were achieved with only 10 mL of water if post-column fluorescence derivatization (Pickering, LC-GC, 1988, 6, 994) and detection at 465 nm (excitation at 330 nm) was applied. C-18 Empore extraction disks were coupled online with liquid chromatography-rapid scanning UV-VIS detection and post-column fluorescence detection for the isolation and trace enrichment of various pesticides spiked at concentration levels of 0.2 and 5 µg/l in drinking water samples. Recoveries were dependent on the pesticide level and pre-concentrated water volume (50 mL to 1000 ml) using LC with rapid scanning UV-VIS detection. The same online system coupled with LC-post-column derivatization fluorescence detection has needed only 10 mL of water to achieve similar levels of determination for the carbamate insecticides.
Pesticides LC Spectrophotometry Sample preparation Extraction

"Fast Screening Method For Eight Phenoxyacid Herbicides And Bentazone In Water. Optimization Procedures For Flow Injection Analysis-thermospray Tandem Mass Spectrometry"
J. Chromatogr. A 1993 Volume 647, Issue 2 Pages 329-339
Ren&eacute; B. Geerdink and Paul G. M. Kienhuis, Udo A. Th. Brinkman

Abstract: A two-step procedure was used to optimize instrumental parameters in the cited techniques (details given). Surface or drinking water (3-5 mL) was injected into a carrier solution (1.5 ml/min) of 0.1 M ammonium acetate/acetonitrile (9:1) and analyzed by MS with a thermospray interface at vaporizer and source block temperature 105 and 200°C, respectively. The parent ion intensities were obtained in the single-scan Q3-MS scan mode and daughter ions after collision with Ar at 3-4 mTorr and collision offset voltage l8 and 22 eV, respectively, for phenoxyacid herbicides and bentazone (I). Multiple-reaction monitoring was used with monitoring of two parent ion-daughter ion pairs for the phenoxyacids and one parent and three daughter ions for I (m/e values given). Calibration graphs were linear for 50 µg/l of each analyte with detection limits of 0.2 µg/l for 2,4,5-(trichlorophenoxy)propionic acid to 0.8 µg/l for 2,4,5-(trichlorophenoxy)acetic acid. The method was fully automated with a sample analysis time of 10 min. Results obtained agreed well with those of LC with UV detection.
Herbicides Bentazone 2,4,5-Trichlorophenoxypropionic acid 2,4,5-Trichlorophenoxyacetic acid Mass spectrometry Optimization Method comparison

"Application Of An Automated Quasi-continuous Immuno Flow Injection System To The Analysis Of Pesticide Residues In Environmental Water Samples"
Sens. Actuat. B 1993 Volume 15, Issue 1-3 Pages 119-126
Christine Wittmann and Rolf D. Schmid

Abstract: The cited FIA system (diagram of manifold presented) was used to determine trace atrazine, the results being compared with those obtained by enzyme immunoassay, GC and HPLC. The atrazine derivative 6-~[4-chloro-6-(isopropylamino)-1,3,5-triazin-2-yl]amino~hexanoic acid was conjugated to BSA and used to raise antibodies in rabbits, and was also coupled to peroxidase for use as tracer. The usable range for atrazine was 30 ng/l-1 µg/l, the mid-point of which (100 ng/l) corresponded to the maximum concentration permitted by EC guidelines for drinking water. RSD were 3-20% for the cited technique as compared with 2-10% for enzyme immunoassay. The cited technique does not require concentration or clean up steps.
Pesticides Atrazine Immunoassay Automation Method comparison

"Online Focused Microwave Digestion-hydride Generation Of Inorganic And Organic Selenium: Total Determination And Inorganic Selenium Speciation By Atomic Absorption Spectrometry"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1849-1857
J. Manuel Gonz&aacute;lez LaFuente, M. Luisa Fern&aacute;ndez S&aacute;nchez, J. Manuel Marchante-Gay&oacute;n, J. Enrique S&aacute;nchez Uria and Alfredo Sanz-Medel*

Abstract: Online pretreatment with HBr and KBrO3 and digestion in a Prolabo Microdigest M301 oven in the manifold described (diagram presented) before treatment with NaBH4 solution (introduced by a second peristaltic pump) renders the proposed method virtually independent of the Se species present. In the absence of organoselenium compounds, inorganic Se(IV) and Se(VI) can be distinguished by sequential injection with and without power to the oven, when total Se and Se(IV) only can be determined, respectively. The detection limit is 0.8 µg/l of Se.
Selenium Spectrophotometry Speciation Microwave Online digestion

"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

"Differential Determination Of Arsenic(III) And Total Arsenic Using Flow Injection Online Separation And Preconcentration For Graphite-furnace Atomic Absorption Spectrometry"
Spectrochim. Acta B 1991 Volume 46, Issue 14 Pages 1789-1801
M. Sperling, Xuefeng Yin and B. Welz

Abstract: Trivalent As was extracted online using Na diethyldithiocarbamate as complexing agent and As(V) was reduced to As(III) with HCl- Na2S2O3 - Na2O3 - KI (preparation described). Online solid-phase extractive pre-concentration was performed on a C18 column, and As(III) and total As were determined sequentially by graphite-furnace AAS. Detection limits were 0.32 and 0.43 ng for As(III) and total As, respectively. A 7.6-fold enhancement in peak area was obtained with a 1-min pre-concentration as opposed to the direct injection of 40 µL samples. Results obtained for synthetic mixtures agreed well with expected values. The method was applied to seawater, lake water and drinking water. The coefficient of variation (n = 10) was 5.5% for 1.65 µg L-1 of total As in seawater.
Arsenic(3+) Arsenic, total Spectrophotometry Sample preparation C18 Extraction Preconcentration

"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
H. ISHII, M. AOKI, T. AITA and T. ODASHIMA

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

"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
H. MORITA, M. SUGIMOTO and S. SHIMOMURA

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

"Flow Injection Analysis For Trace Aluminum With Online Preconcentration And Spectrophotometric Detection"
Anal. Sci. 1994 Volume 10, Issue 2 Pages 287-291
J. KOBAYASHI, M. BABA and M. MIYAZAKl

Abstract: Tap water or Al sample solution in 0.01 M succinic acid/NaOH buffer of pH 6 and 0.1% hydroxylammonium chloride was injected into an FIA system (schematic diagram given). The sample was loaded at 5 ml/min onto a concentrator column (5 cm x 4.6 mm i.d.) of salicylideneamino-2-thiophenol immobilized on glass beads and the system was flushed (1 ml/min) for 10 min with water to remove non-retained Al. Elution was effected with 0.1 M HNO3 acid (1 ml/min) by back-flushing the column for 8 min. The eluate was mixed with pyrocatechol violet in 0.5 M succinate of pH 6 and reacted in a coil (5 m x 0.5 mm i.d.) at 40°C and 1 ml/min. The resulting pyrocatechol violet-Al complex was determined at 576 nm. The calibration graph was linear for up to 500 ng of Al with a determination limit of 3.7 nM and RSD (n = 3) of 0.9% at 25 ppb and 1.5% at 50 ppb of Al.
Aluminum Spectrophotometry Preconcentration Glass beads

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

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

"Trace Metal Preconcentration In Ion Chromatography Using Biochelating Silicas"
Anal. Proc. 1992 Volume 29, Issue 1 Pages 21-23
Jeremy D. Glennon and Noel Ryan

Abstract: Trace metals in tap water and seawater samples (0.1 ml) were determined by ion chromatography after pre-concentration. on a Tefzel cartridge column (5 cm x 4 mm) packed with a chelating solid-phase material based on silica particles (40 µm) or dextran-coated silica particles. The samples were analyzed on a Dionex 4500i column with 4-(2-pyridylazo)resorcinol as a post-column derivatization reagent and detection at 520 nm. Detection limits were 5 to 10 ppb for Cu2+, Co2+, Zn2+ and Ni2+, 20 ppb for Pb2+ and 30 ppb for Cd2+.
Copper(II) Cobalt(II) Zinc(II) Nickel(II) Lead(2+) Cadmium(2+) HPIC Chelation Silica Post-column derivatization Preconcentration

"Online Preconcentration And Determination Of Lead By Fibrous Alumina And Flow Injection - Atomic Absorption Spectrometry"
Anal. Proc. 1994 Volume 31, Issue 2 Pages 61-63
Shayessteh Dadfarnia, Ian Green and Cameron W. McLeod

Abstract: Water was acidified to pH 2 with HNO3 and left to stand overnight. After adjustment to pH 8 with NH3 solution, the sample was passed at 4.5 ml/min through a PTFE micro-column (4 cm x 1.5 mm i.d.) of fibrous alumina, previously made basic with 0.1 M NH4OH (carrier stream). Elution was effected at 4.5 ml/min with 1 M HNO3 and the eluate was transported to an air-acetylene flame for AAS analysis with measurement at 283.3 nm. The calibration graph was linear for 2.5-100 µg/l of Pb; the detection limit was 0.7 µg/l. The RSD (n = 7) for 2 and 5 µg/l of Pb were 2.3 and 4.9%.
Lead Spectrophotometry Alumina Column Preconcentration

"Stopped-flow Thin-layer-coulometric Method For The Determination Of Disinfectants In Water"
Anal. Proc. 1995 Volume 32, Issue 1 Pages 13-15
Stephen Dennison and David M. Bonnick

Abstract: A coulometric technique, using a thin layer electrochemical cell and stopped-flow sampling to minimize interference from non-faradaic contributions to the signal, has been developed and applied to the analysis of oxidants employed in water treatment. It is shown that the coulombic efficiency of the method is very close to 100%, resulting in a linear relationship between charge and analyte concentration.
Disinfectants Coulometry Stopped-flow

"Mechanized Catalytic Spectrophotometric Determination Of Iron In Drinking Water By The Continuous-flow Principle"
Acta Hydrochim. Hydrobiol. 1979 Volume 7, Issue 3 Pages 281-288
Dr. H. Schurig Dr. sc. H. M&uuml;ller

Abstract: Es wird eine katalytisch-spektralphotometrische Eisenbestimmung im Trinkwasser mit einem "continuous-flow"-Analysator beschrieben. Die Bestimmungsmethode basiert auf der Eisen-katalysierten Oxydation von p-Phenetidin durch Wasserstoffperoxid mit 1,10-Phenanthrolin als Aktivator. Die Analysenfrequenz beträgt 30 Proben/h. Die mittlere relative Standardabweichung der Bestimmung liegt für Eisenkonzentrationen von 5-140 µg/l bei ±5%. Der Störeinfluß von Fremdionen auf die katalytische Eisenbestimmung wurde anhand einer Modellösung ("simuliertes Trinkwasser") getestet. Die Ergebnisse zeigten, daß die normalerweise im Trinkwasser vorhandenen mineralischen Bestandteile die Bestimmung nicht stören. Die Richtigkeit der in Trinkwasserproben katalytisch gefundenen Eisenwerte wurde durch eine manuell ausgeführte, photometrische Standardmethode abgesichert.
Iron Spectrophotometry Catalysis Interferences

"FIA Determination Of Chromium(III) In Tap Water With Chemiluminescence Detection"
Anal. Commun. 1998 Volume 35, Issue 12 Pages 389-390
A. Economou, A. K. Clark and P. R. Fielden

Abstract: Cr(III) has been determined by measuring the light emitted as a result of the Cr(III)-catalyzed reaction between luminol and hydrogen peroxide. Increase in the sensitivity of the determination was achieved by introducing bromide into the reaction mixture while the selectivity was improved by the addition of EDTA. All the operations were performed online in an automated FIA system. The calibration curve for Cr(III) was linear in the range 0-500 µg L-1 and the limit of detection was 0.5 µg l-1. The method was applied to the determination of Cr(III) in tap water; the Cr(III) concentration. varied between 10 and 20 µg L-1 with a typical coefficient of variation of 2% (n = 5).
Chromium(III) Chemiluminescence Indirect EDTA

"Spectrophotometric Determination Of Magnesium(II) By Flow Injection Analysis Using Succinimide Dioxime"
Analusis 1987 Volume 15, Issue 3 Pages 136-139
Forteza, R.;Cerda, V.;Maspoch, S.;Blanco, M.

Abstract: The method was based on the inhibition by Mg of the formation of the blue product of the Mn(II)-catalyzed oxidation of succinimide dioxime(I). The sample solution (125 µL) was injected into a stream (0.45 mL min-1) of 0.02 M nitrilotriacetic acid in 13 mM NaOH as masking agent for alkaline-earth metals. This stream was mixed in a 0.5-m coil with a stream containing I (1 g l-1) and Mn(II) (4 mg l-1). The mixed streams were introduced into a stream of 1.5 M NaOH (0.9 mL min-1) in a 4-m coil at 35°C and the absorbance of the solution was measured at 695 nm. Calibration graphs were rectilinear from 0.5 to 8 mg L-1 of Mg. For 5 mg L-1 of Mg, the coefficient of variation was 2% (n = 12) and there was no interference from up to 150, 150 or 300 mg l-1, of Ca, Sr or Ba, respectively. The tolerance limits of nine other cations and 13 anions were also determined. The method was applied to drinking water and common salt, giving results which agreed with those of AAS.
Magnesium(II) Spectrophotometry Catalysis Heated reaction Interferences Method comparison Indirect

"Flow Injection Analysis Of Several Aromatic Pesticides Using Fluorescence And Photoinduced Fluorescence Detection"
Analusis 1996 Volume 24, Issue 4 Pages 107-112
A Coly, JJ Aaron

Abstract: The FIA apparatus used was as described previously (cf., Anal. Chim. Acta, 1992, 269, 193), the various parts of the apparatus being connected with PTFE tubing (0.5 mm i.d.). The pesticides studied were bendiocarb, chlorophacinon, coumatetralyl and pirimiphos-methyl (which fluoresce naturally) and fenitrothion, fenvalerate, deltamethrin and diflubenzuron (which fluoresce under 254 nm radiation). For the photo-induced fluorescence, the mobile phase/sample mixture passed through a reaction coil (2.5 m), loosely wrapped round an 8 W germicidal lamp and covered with Al foil. The parameters optimized were the type of mobile phase, flow rate, sample volume, reactor and mixing tube lengths and excitation and emission wavelengths (tabulated). Calibration graphs were linear over two orders of magnitude, ranging from 0.1-20 ng/ml for coumatetralyl to 0.11-15.7 µg/ml for bendiocarb (both with 0.3 mL injected), with detection limits of 0.02-22 ng. Methods are given for extracting the pesticides from technical formulations, with recoveries of 91.9%. In a mixture of fenitrothion and fenvalerate (sumicombi) there was interference from fenvalerate, but the mixture could be analyzed by selective suppression of fenitrothion fluorescence (in methanol solution) and of fenvalerate fluorescence (in DMSO). The method was applied to the determination of five pesticides in tap water.
Pesticides Bendiocarb Chlorophacinon Coumatetralyl Pirimiphos-methyl Fenitrothion Fenvalerate Deltamethrin Diflubenzuron Fluorescence Photochemistry UV reactor Interferences Optimization

"Electrochemiluminescence Flow Injection Immunoassay For Atrazine"
Biosens. Bioelectron. 1997 Volume 12, Issue 4 Pages 277-286
Robert Wilson*, Michael H. Barker, David J. Schiffrin and Ram Abuknesha

Abstract: Antibodies to atrazine were labelled with glucose oxidase and used in colorimetric enzyme linked immunosorbent assays. Transparent aminosilanized indium tin oxide coated glass electrodes were derivatized with aminodextran covalently modified with atrazine caproic acid. The labelled antibodies were used to investigate the derivatized electrodes colorimetrically and the electrodes were use in an electrochemiluminescence flow injection analyzer.. Electrochemiluminescence immunoassay for atrazine in the range 0-10 ppb showed that it was possible to detect less than 0.1 ppb, the precautionary limit for pesticides in drinking water recommended by the European Commission.
Atrazine Pesticides Chemiluminescence Immunoassay Electrode Electrode Apparatus Detector

"Development Of An Amperometric Flow Injection Immunoanalysis System For The Determination Of The Herbicide 2,4-dichlorophenoxyacetic Acid In Water"
Biosens. Bioelectron. 1997 Volume 12, Issue 6 Pages 499-510
Dieter Trau, Thomas Theuerl, Marianne Wilmer, Markus Meusel*, and Friedrich Spener

Abstract: An amperometric flow injection immunoanalysis (FIIA) system based on an immunoreactor with immobilized biocomponents on a silica surface has been developed for the determination of the herbicide 2,4- dichlorophenoxyacetic acid (2,4-D). In the antigen coating mode the hapten was immobilized and monoclonal primary antibody against 2,4-D together with alkaline phosphatase (AP)-labelled secondary antibody were used as sensing elements in a titration assay. In the antibody coating mode a biotinylated monoclonal antibody was immobilized on the surface of the immunoreactor and a 2,4-D-AP-conjugate was used for detection. For electrochemical measurements p-aminophenol enzymatically generated from p-aminophenyl phosphate was oxidized at a carbon working electrode at +150 mV versus Ag/AgCl. The system enabled the determination of 2,4-D in drinking water samples in the range from 0.2 to 70 µg/l. The whole system was computer controlled with a measuring time of 12 min for one determination.
2,4-dichlorophenoxyacetic acid Endothall sodium Immunoassay Amperometry Electrode Electrode Titrations Computer

"A Chemiluminescent FIA Biosensor For Phosphate Ion Monitoring Using Pyruvate Oxidase"
Biosens. Bioelectron. 1997 Volume 12, Issue 9-10 Pages 959-966
Hideaki Nakamura*, Kazunori Ikebukuro, Scott McNiven, Isao Karube, Hiroyuki Yamamoto, Kenji Hayashi, Masayasu Suzuki and Izumi Kubo

Abstract: We have constructed an automatic phosphate ion sensing system for the quality control of drinking water. The analyte was detected using the phosphate ion-dependent pyruvate oxidase reaction and the hydrogen peroxide produced was detected by luminol chemiluminescence catalyzed by Arthromyces ramosus peroxidase. We obtained a detection limit of 0.16 µM phosphate ion (5 ppb phosphorus) and it was possible to detect 0.32 µM phosphate ion for 48 days using pyruvate oxidase immobilized on Chitopearl BCW-2601 beads. An excellent correlation (r2 = 1.00) was obtained between the results obtained using our phosphate ion sensor and those using a modified Molybdenum Blue method.
Phosphate Chemiluminescence Sensor Immobilized enzyme Method comparison Indirect

"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

"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
Shoji MOTOMIZU

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

"Fluorimetric Determination Of Boron With Chromotropic Acid By Continuous-flow System"
Bunseki Kagaku 1983 Volume 32, Issue 8 Pages 458-463
Motomizu, S.;Oshima, M.;Toei, K.

Abstract: The sample (160 µL) was injected into a carrier stream of water, which was then mixed with a stream of reagent solution (0.073 g of chromotropic acid in 500 mL of 1 M acetate buffer of pH 6.1 containing 0.37 g of EDTA) in a 3 m tube (0.5 mm i.d.). The fluorescence of the resulting mixture was measured at 350 to 360 nm (excitation at 313 nm). Interfering species, e.g., Ca, Mg, Al and Fe, were removed by pre-treatment of the sample with Amberlite IR-122 resin (Na+ form). The calibration graph was rectilinear for 0.5 ppb to 5 ppm of B. The detection limit was 0.2 ppb; coefficient of variation were 0.8, 0.5 and 0.6% for 5.0 ppb, 4.23 ppm and 339 ppb of B in tap-water, seawater and hot-spring water, respectively.
Boron Ion exchange Fluorescence Amberlite Interferences Resin

"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

"Determination Of Calcium By Flow Injection Analysis With Hydroxynaphthol Blue"
Bunseki Kagaku 1985 Volume 34, Issue 9 Pages 568-572
Uchida, K.;Tomoda, M.;Saito, S.

Abstract: Calcium has been determined in natural and tap waters by a method based on the change in absorbance at 455 nm of hydroxynaphthol blue(I) caused by formation of a Ca - I complex at pH 13; no masking reagent for Mg is required. The flow injection system was optimized as regards mixing-coil length, reaction-coil length, flow rate, pH and wavelength. Barium, Zn and Al did not interfere, Mg, Sr and Fe did not interfere in concentration. equal to the Ca concentration, Ni, Cu and Mn gave negative errors and Cd gave positive errors. Response was rectilinear for Ca concentration. from 1.2 to 3.9 mg l-1. About 40 samples could be analyzed in 1 h and the coefficient of variation (n = 15) was 1.12%. Results agreed with those by standard EDTA titration.
Calcium Hardness Spectrophotometry Interferences Optimization

"Determination Of Copper(II) At The Sub-picogram Level By Flow Injection Method Using Micelle-enhanced Chemiluminescence Of 1,10-phenanthroline"
Bunseki Kagaku 1986 Volume 35, Issue 4 Pages 373-378
Ishii, M.;Yamada, M.;Suzuki, S.

Abstract: Tap water was analyzed by flow injection analysis with use of three flow lines at a constant aggregate flow of 7.4 mL min-1. The sample was mixed with 60 µM-1,10-phenanthroline - 0.12 M NaOH - 25 mM ethylhexadecyldimethylammonium bromide and aqueous 6% H2O2, and the chemiluminescence was measured. The limit of detection was 4 fg µL-1 of Cu(II) (20 µL injected) or 0.16 pM-Cu (for continuous sample flow), and the calibration graphs were rectilinear over 4 orders of magnitude. The coefficient of variation was <1.7%. The signal from Pb(II) was 0.03% of that for Cu.
Copper(II) Chemiluminescence Interferences Micelle

"Potentiometric Flow Injection Determination Of Total Water Hardness In Tap Water By Using Cupric Ion Buffer"
Bunseki Kagaku 1990 Volume 39, Issue 2 Pages 135-138
Imato, T.;Ishii, K.;Ishibashi, N.

Abstract: Sample solution (200 µL), containing Ca2+ or Mg2+, was injected into a carrier stream (0.9 mL min-1) of water which then merged with a stream (0.9 mL min-1) of 0.5 M NaNO3. The mixed stream merged with a stream (0.9 mL min-1) of 5 mM Cu(NO3)2 - 0.1 mM EDTA. The mixture was passed through a reaction coil (5.4 m x 0.5 mm) and the Cu2+ released was detected at a Cu2+-selective electrode. The coefficient of variation was 0.7% and the analysis time was 30 samples h-1. Interference by Cl- and Br- could be masked by addition of triethylenetetramine to the cupric ion buffer solution
Calcium Magnesium Potentiometry Electrode Buffer Interferences

"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

"Sensitive Determination Of Hydrogen Peroxide By FIA Using An Enhanced Luminol Chemiluminescence System With A Mixed Dye-sensitizer"
Bunseki Kagaku 1992 Volume 41, Issue 3 Pages 125-133
Ishii, M.;Shirai, M.

Abstract: The method is based on the enhancement of the chemiluminescence of the luminol - H2O2 system that occurs in the presence of eosin Y (C.I. Acid Red 87) and uranin (C.I. Acid Yellow 73). The luminol - NaOH - eosin Y - uranin solution is injected into the aqueous carrier stream (8 mL min-1) from a 0.1 mL sample injector mounted 50 cm from the detector, and the sample solution is injected from a 20 µL injector mounted 20 cm from the detector. The detection limit was 10 pM-H2O2, and the coefficient of variation (n = 10) at 10 nM-H2O was 1.7%. Weak interference was caused by µM concentration. of heavy-metal ions. The method was used to determine H2O2 in tap water; recoveries were almost quantitative. A mixed dye-sensitizer (eosin Y/uranine) was applied to H2O2 determination at ultratrace levels using luminol chemiluminescence system. The proposed single line FIA system was equipped with 2 sample injectors (Rheodyne, 7125 type) placed on the flow line at a distance of 30 cm from each other; the large one (100 µL) at a distance of 10 cm from the pump was employed for the CL reagent solution and the small one (20 µL) at a distance of 20 cm to the detector for the H2O2 solution (sample). The lower detection limit: 1 x 10^-11 M in 20 µL injection volume, relative standard deviation: 1.7% in 10 repeated runs involving a 20 µL injection of the 1 x 10^-8 M H2O2 solution, anal. time: ~5 s.
Hydrogen peroxide Chemiluminescence Indirect Interferences Ultratrace

"Spectrophotometric Determination And FIA Of Aqueous Ozone Based On The Decolorization Reaction Of The 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)aniline-iron(II) Complex"
Bunseki Kagaku 1994 Volume 43, Issue 8 Pages 635-639
Onari, Y.

Abstract: The degree of decolorization at 560 nm of the 3-[3-amino-4-(5-bromo-2-pyridylazo)-N-propylanilino]propanesulfonic acid-Fe(II) complex varied linearly with the concentration of O3 (apparent ε = 3604), and the detection limit was 30 µg/l. An FIA manifold for determination on the same principle is illustrated. The RSD (n = 5) at 1.47 mg/l of O3 was 0.48%, and the sampling rate was 40 per h. Normal components of drinking water did not interfere.
Ozone Spectrophotometry Interferences

"Fluorometric Determination Of Trace Amounts Of Copper(II) Using Online Adsorption Preconcentration In Teflon Capillary Tubes"
Bunseki Kagaku 1998 Volume 47, Issue 3 Pages 179-185
Kunihiro Watanabe, Kunihiro Ohba, Arkin Iburaim, Masayuki Itagaki and Nobuyuki Koura

Abstract: A new pre-concentration. online system for trace Cu(II) determination was developed based on the adsorption of Cu(II) on the walls of Teflon tubes using flow injection analysis (FIA). Cu(II) was concentrated as hydroxide or colloid on the inner walls of Teflon tubes. The present FIA app. had triple channels, and dual injectors were used in a carrier stream. A nitric acid solution (100 µL) was loaded in the sample loop of one injector. The sample solution containing Cu(II) was loaded in another injector, where Cu(II) was adsorbed. The Cu(II) adsorbed on a Teflon capillary tube (3 m in length, i.d. 0.5 mm) was eluted online with a nitric acid solution, and was then determined with ascorbic acid and o-phenylenediamine by fluorometry. The Cu(II) was determined over the range of 0.025-200 ppb by the present method. The detection limit for Cu(II) was 0.008 ppb. The RSD was 2.3% for 1 ppb Cu(II) (n = 7). The treatment of Teflon tubes with a 2 m NaOH solution enhanced the adsorption of Cu(II). The optimum conditions of Cu(II) determination by the present method were as follows: sample solution, pH 6.0; NaOH concentration, 2 M; adsorption flow rate, 0.4 mL/min; adsorption time, 10 min. The interference in the determination of Cu(II) with diverse ions, i.e. V(V), Cr(VI), Fe(III), Hg(II), Mn(II), Cd(II), La(III), Y(III), and Tl(I) could be decreased by adsorption pre-concentration. without a masking agent. The results of a trace Cu(II) determination in tap water showed good agreement with the values obtained by graphite-furnace AAS.
Copper(II) Fluorescence Preconcentration Tube wall immobilization Dual injection Interferences Method comparison Optimization

"Applications Of An Online Pre-concentrating Flow Injection Analysis System For Inductively Coupled Plasma Atomic-emission Spectrometry"
Can. J. Anal. Sci. Spectrosc. 1985 Volume 30, Issue 6 Pages 144-148
Hartenstein, S.D.;Christian, G.D.;Ruzicka, J.

Abstract: The flow injection portion of the system described previously (Anal. Chem., 1985, 57, 21) has been re-designed to improve the collection efficiency. A single-column manifold is described in which the sample solution (8 mL min-1) is mixed with 1.2 M ammonium acetate buffer of pH 9.2 (0.8 mL min-1) and analyte metals are collected for 150 s on a 0.3 mL column of Chelex 100. Elution to the ICP is then effected for 90 s with 2 M HNO3 (1 mL min-1), and either the signals are integrated for 30 s (for simultaneous multi-element determinations) or the peak height for a single metal is measured. Detection limits are improved four- to five-fold with respect to those reported previously (loc. cit.), and rectilinear ranges are extended downwards five- to fifty-fold. The sampling rate is 12 to 20 h-1. The method has been applied to the determination of various metals in tap-water and run-off water.
Metals Spectrophotometry Chelex Preconcentration Resin

"Method Of Flow Injection Analysis - Chloride Estimation In Water"
Cesk. Hyg. 1989 Volume 34, Issue 3 Pages 174-178
Krajak, V.

Abstract: An outline of the principles behind the flow injection analysis (FIA) method is given, and benefits of this method in rapid and easy anal. of a large number of samples are discussed. The method was applied with good results to the determination of Cl- in potable and surface waters using Hg(SCN)2 as the reagent and a spectrophotometer as the detector. (SFS)
Chloride Spectrophotometry

"Gas Diffusion Flow Injection Analysis Applied To The Determination Of Sulfite And Sulfur Dioxide In Environmental Samples"
Chem. Anal. 1995 Volume 40, Issue 4 Pages 619-630
Frenzel, W.;Hillmann, B.

Abstract: To determine free sulfite, sample (300 µL) was injected into a carrier stream (1.2 ml/min) of water which merged with a stream (0.8 ml/min) of 0.2 M H2SO4 and passed through a reaction coil (60 cm x 0.7 mm i.d.). The SO2 produced was transferred to a stream (0.6 ml/min) of color reagent (50 mg 4,4'-dithiodipyridine, 10 mL ethanol and 1.02 g potassium hydrogen phthalate diluted to 250 mL with H2O) in a gas diffusion unit. It then passed through a reactor (45 cm x 0.7 mm i.d.) and the absorbance was measured at 324 nm. To determine gaseous SO2 collected in formaldehyde solution, samples (500 µL) were injected into a H2 carrier and treated with 0.45 M NaOH prior to acidification and release of SO2 (FIA manifold shown). The calibration graphs were linear for 0.25-10 and 0.5-20 mg/l free and bound sulfite, respectively, and the detection limits were 0.08 and 0.15 mg/l, respectively. The RSD were 1-3% and the sampling frequency was 20-30/h. Interferences were investigated. The methods were applied to the determination of sulfite in tap, surface and waste waters and brine, and to the determinations of SO2 in air (details given).
Sulfite Sulfur dioxide Spectrophotometry Gas diffusion Interferences

"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

"Determination Of Ultratrace Amounts Of Selenium(IV) In Water And Soil Extracts By Flow Injection Online Ion-exchange Preconcentration Hydride Generation Atomic Absorption Spectrometry"
Kexue Tongbao 1990 Volume 35, Issue 6 Pages 526-527
XU SHU-KUN, ZHANG SU-CHUN, FANG ZHAO-LUN

Abstract: Sample solution (9 mL min-1) was merged with 0.2 M acetate buffer (pH 5; 0.5 mL min-1) before passing through a column (4.5 cm x 3 mm) of D201 macroporous anion exchanger (50 mesh). Selenium was eluted with 1 M HCl (6 mL min-1) and the eluate was mixed with 0.5% of NaBH4 in 0.1% NaOH solution (2 mL min-1). The SeH4 was separated in a gas - liquid separator and carried by Ar (150 mL min-1) to a silica atomizer heated at 700°C for determination by AAS at 196.0 nm. The detection limit was 2 ng l-1, and the sampling rate was 50 h-1. The coefficient of variation were 1.1% (n = 11) for 0.5 µg L-1 and 6.4% (n = 10) for 0.01 µg l-1. Recoveries from tap, well and mineral waters were 96 to 100% and from soil extracts were 92 to 102%.
Selenium(IV) Ion exchange Spectrophotometry Clinical analysis Sample preparation Preconcentration Buffer pH Phase separator Detection limit Ultratrace Volatile generation

"Simultaneous Determination Of Iron And Copper In Waters By Multiligand Flow Injection Analysis"
Collect. Czech. Chem. Commun. 1988 Volume 53, Issue 7 Pages 1461-1475
Kuban, V.;Gladilovich, D.B.

Abstract: The spectrophotometric characteristics were studied and optimum conditions were established for the determination of Fe and Cu with mixtures of disodium 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulfonate(I) with disodium 4,7-diphenyl-1,10-phenanthrolinedisulfonate(II) or 3-(2-pyridyl)-5,6-bis(4-sulfophenyl)-1,2,4-triazine (disodium salt) in static and dynamic flow injection systems. In the recommended procedure, 30 µL water samples containing Fe and Cu in concentration. ratios from 1:10 to 10:1 are injected into a stream of 0.6 M I - 0.2 mM II in 0.1 M formate buffer (pH 3.5) - 0.01 M ascorbic acid. The coefficient of variation for 4 to 40 µM-Fe and -Cu were 2 and 5%, respectively. In the reverse flow injection method, 25 µL of reagent mixture is injected into the acid sample stream; multi-channel diode-array detection is used. The coefficient of variation for Fe and Cu concentration. of 1 to 43 µM in ratios of 10:1 to 1:15 is ~2%. The methods were applied in the analysis of drinking and surface waters.
Iron Copper Spectrophotometry Multicomponent Reverse Optimization Simultaneous analysis

"Flow Injection Analysis Of Carbonate, Sulfite And Acetate In Food"
Dtsch. Lebensm. Rundsch. 1996 Volume 92, Issue 10 Pages 323-328
SHI R. ; STEIN K. ; SCHWEDT G.

Abstract: For carbonate, drinking water was analyzed directly, mineral water was ultrasonically degassed, and orange drink was ultrasonically degassed and diluted with water (1:2). Sulfite in white wine was determined directly. For acetate, pickled gherkins and pepperoni were extracted with water. Solutions were injected into a water carrier, the stream was mixed with 5 mM H3PO4 to release the acidic gas or vapor, and this diffused into bromocresol violet/bromothymol blue/cresol red/KCl indicator in carbonate buffer (pH 8.3) for photometric detection at 430 nm or into dilute NaOH of pH 9.5 for potentiometric detection, or into iodine/KI/starch solution of pH 9.5 for photometric detection of sulfite at 620 nm. Alternatively, for acetate, the sample solution was adjusted to pH 8.4 with NaOH and injected into FeCl3 for photometric determination of the Fe-acetate complex at 405 nm. Conditions were optimized (details given), and means of overcoming interference are given. The iodimetric method was preferred for sulfite. Results agreed well with those of standard methods.
Sulfite Carbonate Acetate ion Spectrophotometry Potentiometry Interferences Standard method Method comparison Optimization

"Determination Of Trace PAHs In Water Samples By Synchronous Fluorophotometry With Flow Injection And Column Preconcentration"
Fenxi Ceshi Xuebao 1998 Volume 17, Issue 2 Pages 68-70
Lin Yuhui, Zhang Yong, Yuan Dongxing

Abstract: A simple and rapid synchronous fluorophotometric method couples with flow injection and column pre-concentration is described for the online simultaneous determination of trace benzo[a]pyrene (BaP) and perylene (Per) in tap and well water. The detection limits of BaP and Per are 0.2 µg.L-1 and 0.04 µg.L-1, respectively. The relative standard deviations are 7.10% and 7.54%, respectively. The recoveries are 93.3-103.3% and 103.3-116.7%, respectively.
Hydrocarbons, aromatic, polycyclic Benzo(a)pyrene Perylene Fluorescence Column Preconcentration

"Determination Of Trace Amounts Of Nickel By Online Flow Injection Analysis Ion-exchange Preconcentration Atomic Absorption Spectrometry"
Fenxi Huaxue 1984 Volume 12, Issue 11 Pages 997-999
Fang, Z.L.;Xu, S.K.;Zhang, S.

Abstract: The flow injection technique combined with ion-exchange pre-concentration permitted efficient online determination of Ni by AAS Miniature columns (3.5 cm x 2.5 to 3.0 mm) of PVC or glass were used, packed with chelating resin (type 122; 60 to 100 mesh) with a salicylic acid functional group, and sealed at both ends with nylon net (100 mesh). By means of a multi-functional rotating sampling valve, it was possible to carry out sampling, ion exchange, elution with 2 M HCl and AAS determination sequentially. A 20-fold improvement in sensitivity for the determination of 10 to 500 µg L-1 of Ni was attained; the coefficient of variation at the 500 µg L-1 level was 1.5%. Recovery from tap water and surface water was 90 to 106%. The effect of factors which affect sensitivity, viz, particle size of the exchange resin, column dimension and flow rate of eluate, are considered. Interference from various metals has been investigated.
Nickel Ion exchange Spectrophotometry Interferences Chelation Resin Preconcentration

"Flow Injection Analysis Micellar-solubilization Spectrophotometry. 1. Determination Of Phosphorus At Microgram/liter Levels With The Ethyl Violet-heteropoly Acid-Triton X-100 System"
Fenxi Huaxue 1987 Volume 15, Issue 11 Pages 1022-1024
Yuan, Y.;Qu, K.

Abstract: The flow of the three reagent solution, viz, (A) 0.06 M in H2SO4 and 3 mM in MoO42-, (B) prepared by mixing 20 mL of 10% Na2S2O3 solution, 60 mL of 10% Na2SO3 solution (to eliminate interference of As(V)), 6 mL of 5% Triton X-100 solution and water to produce 200 ml, and (C) aqueous 0.12 mM ethyl violet (C. I. Basic Violet 4), is controlled by a peristaltic pump at 1.43 mL min-1, 0.67 mL min-1 and 1.41 mL min-1, respectively. solution A and B are mixed just before the injection of 1 mL of the sample or standard P solution (e.g., 42 µg l-1). solution C enters the system after passage of the sample solution through a coiled reaction tube (90 cm x 0.3 mm) and flow continues through another coiled reaction tube (300 cm x 0.8 mm) to an 8 µL detector cell for absorbance measurement at 553 nm. The calibration graph is rectilinear for up to 100 µg L-1 of P. The detection limit is 0.5 µg l-1. The method has been successfully applied to the determination of trace P in tap and well water.
Phosphorus Spectrophotometry Micelle Interferences Triton X Surfactant

"Stop-flow Reverse Flow Injection Analysis For Trace Manganese The Manganese(II)-sodium Phosphinate (NaH2PO2)-potassium Periodate NTA System"
Fenxi Huaxue 1988 Volume 16, Issue 4 Pages 315-319
Yuan, Y.;Wang, Y.;Qu, K.

Abstract: The water sample (tap water after removal of Cl by boiling, or polluted or well water after removal of bacteria by filtration) was merged with separate reagents of 1.1 mM KIO4 (40 µL) and 16% hexamine - HCl - NaOH buffer (pH 6.6), containing 0.15 mM NaH2PO2 and 0.3 mM nitrilotriacetic acid, in the stopped-flow apparatus (diagram given), and reacted in a 70-cm tube for 5 min followed by elution and absorbance measurement of Mn(II) at 236 nm. Both sample matrix and the hexamine reagent act as carriers. A rectilinear calibration graph is obtained for up to 5 µg L-1 of Mn(II) and the detection limit is 0.05 µg l-1. For determination of 3 µg L-1 of Mn(II), the coefficient of variation is 3% (n = 10). Most foreign ions, e.g., Al(III), Ba(II) (2 µg mL-1), Cr(VI) (6) and Pb(II) (1.6) do not interfere but Co(II) (>4 ng mL-1) produces a negative interference.
Manganese Spectrophotometry Interferences Reverse Stopped-flow

"Flow Injection Analysis Micellar-solubilization Spectrophotometry. 2. Simultaneous Spectrophotometric Determination Of Calcium And Magnesium With Xylenol Orange-cetyltrimethylammonium Bromide System"
Fenxi Huaxue 1988 Volume 16, Issue 6 Pages 546-548
Yuan, Y.;Wang, Y.;Qu, K.

Abstract: Flow injection analysis was used for the simultaneous spectrophotometric determination of Ca and Mg as complexes with xylenol orange in the presence of hexadecyltrimethylammonium bromide. Calcium and Mg were determined at 585 nm in a medium of NH3 - NH4Cl buffer (pH 10.5) containing triethanolamine, and then Ca was determined at 605 nm in NH3 - NH4Cl - Na citrate buffer containing triethanolamine. The calibration graph was rectilinear for Ca and Mg in the former buffer for up to 8 µg mL-1, and for Ca in the latter buffer, for up to 5 µg mL-1. The coefficient of variation was 1.4% for 4 µg mL-1 of Ca. The method was applied to the determination of Ca and Mg in tap water, well water and seawater. Results agreed well with those obtained by AAS.
Calcium Magnesium Spectrophotometry Complexation Merging zones Method comparison Simultaneous analysis Micelle

"Sequential Determination Of Residual Chlorine And Chloride In Tap-water By Spectrophotometric Flow Injection Analysis"
Fenxi Huaxue 1989 Volume 17, Issue 3 Pages 242-244
Ma, C.;Yang, J.;Zhao, Z.;Wang, J.;Wang, Q.

Abstract: To determine residual Cl, a water sample (320 to 400 µL) is injected into a carrier stream of water (6 mL min-1) to react with a stream (2.4 mL min-1) of 0.086% o-toluidine solution (containing a little HCl) in a 30-cm reaction tube; detection is at 438 nm. For subsequent determination of Cl-, the reagent stream is composed of 0.63 g of Hg(SCN)2, 30.3 g of Fe(NO3)3, 3.4 mL of HNO3, 15 mL of methanol and water to 1 l; otherwise, the same conditions are used. The method is simple, rapid and convenient and gives satisfactory results. To suppress decomposition of residual Cl, the sample should have a high pH (e.g., 9).
Chlorine Chloride Spectrophotometry pH Interferences

"Study Of Flow Injection Analysis With Differential Pulse Stripping Voltammetry"
Fenxi Huaxue 1990 Volume 18, Issue 3 Pages 219-222
Qi, D.;Ying, T.;Pu, T.

Abstract: A flow injection analysis - differential pulse stripping voltammetry system is described. The supporting electrolyte is 50 µM-Hg2+ - 0.05 M KNO3 (pH 4), the working electrode is of vitreous carbon, the counter electrode is a stainless-steel tube and Ag - AgCl is used as the reference electrode. For determining 0.5 µM-Cd, the flow rate was 0.314 l min-1, the sample volume was 500 µL, the scanning rate was 100 mV s-1, the pulse cycle was 100 ms (duration 50 ms), the pulse height was 75 mV, and electro-deposition was carried out for 3 min at -1.2 V. The system is stable, sensitive and reliable. Using this system to determine Pb and Cu in serum and Pb in tap water, results compared well with those obtained by AAS.
Lead Copper Voltammetry Electrode Method comparison

"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

"Interpolative Standard Addition Method In Anodic-stripping Voltammetry With Flow Injection System"
Fenxi Huaxue 1992 Volume 20, Issue 6 Pages 633-637
Gao, G.;Deng, Y.;Qi, D.

Abstract: A new interpolative standard addition method in flow injection analysis (FIA) systems with anodic-stripping voltammetry was developed and a theoretical equation for the stripping peak current under this nonsteady deposition procedure was proposed. With this technique the concentration. of sample (used as carrier) was obtained rapidly by a proposed simple equation only after injecting a standard. The system was applied to the determination of Pb in tap water. Filtered sample was directly injected into the FIA system at 0.6 mL min-1 to merge with a reagent stream of 0.5 M KCl - 0.2 M HCl - 0.1 M ascorbic acid at 0.06 mL min-1 before anodic-stripping voltammetry with use of water as blank and 20 nM-Pb(II) as standard solution Lead was calculated using a given equation. Recovery was 90 to 108%; coefficient of variation (n = 10) was 3.4%. The detection limit was at the ppb level. Results were comparable with those obtained by the conventional anodic-stripping voltammetry.
Lead Sample preparation Voltammetry Standard additions calibration Method comparison

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

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

"Determination Of Iron In Drinking Water And Pharmaceuticals By A First-derivative Stop-flow Method"
Fenxi Huaxue 1994 Volume 22, Issue 7 Pages 695-697
Wang, Z.B.;Zheng, Z.Z.;Jin, M.

Abstract: Drugs or tap water were treated with acetic acid/sodium acetate buffer of pH 5.7, triethylenetetramine and 21 mM tetramethyl-p-phenylenediamine and diluted with water. The solution was injected into an FIA system at 7.9 ml/min to mix with a stream of 1.2% H2O2 at 7.9 ml/min. The streams were programmed to flow for fixed time of 40 s then stop for 45 s, before entering a reactor (13.8 cm long) and detection at 565 nm. Five-fold of Cu(II) did not interfere. The calibration graph was linear for 4-40 ng/ml of Fe(III) with a detection limit of 1.92 ng/ml. Recovery was 98.7-101% with RSD of 2.5%.
Iron(III) Spectrophotometry Interferences Stopped-flow

"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

"A New Flow-cell Optical-fibre Reflected Nickel Ion Sensor"
Fenxi Huaxue 1995 Volume 23, Issue 1 Pages 117-120
Lu, J.Z.;Zhang, Z.J.

Abstract: Amberlyst A-27 anion-exchange resin (0.1 g) was stirred with 10 mL 10 mM nitroso-red salt (I) for 20 min, filtered, washed and the impregnated resin was then used for construction of the cited sensor (diagram illustrated). Sample in 0.1 M HCl/0.1 M Na2B4O7 buffer of pH 9 was allowed to flow at 4 ml/min through the cell and the reflected signal at 500 nm due to reaction of Ni and I was measured; regeneration was by 1 M HCl washing. Response to the concentration of Ni ion was linear for 1-100 M with a detection limit of 1 ng/ml. The method was applied to assay of tap water with recoveries of 95-103% and RSD of 5%. Results compared closely with those obtained by photometry.
Nickel Sensor Optical fiber Method comparison

"Determination Of Fluoride In Water Using An Ion-exchange Preconcentration Flow Injection Ion-selective Electrode"
Fenxi Huaxue 1995 Volume 23, Issue 6 Pages 671-673
Li, J.X.;Liu, G.J.

Abstract: Sample (14.8 ml) was applied (3.7 ml/min) to an ion-exchange column (5 cm x 2.5 mm i.d.) packed with Dowex 1x4 (0.07-0.15 mm) in the ion-exchange flow injection setup for pre-concentration with 10 mM NaNO3 for percolation (1.2 ml/min) and mixed with a stream of 0.1 M citric acid/6% NaOH buffer of pH 6.3 (0.7 ml/min) in a reaction coil (30 cm long), entering a wall-jet type flow-cell (volume of 0.158 ml), where the fluoride-selective electrode was situated, for detection. a 50-fold pre-concentration was achievable. When determining 0.1 µg/ml of fluoride, recovery was 94-106% with RSD of 3.2%. The detection limit was 12 ng/ml of fluoride. Use of double-column switching for ion exchange, sampling frequency was further increased. Sensitivity could be enhanced by adjusting the distance between the inlet nozzle and electrode surface through the position of the inlet tube. The method was applied to analysis of drinking water.
Fluoride Ion exchange Electrode Potentiometry Preconcentration Optimization

"Spectrophotometric Determination Of Mercury With 2-hydroxy-3-carboxy-5-sulfobenzenediazoaminoazobenzene By Flow Injection Analysis"
Fenxi Huaxue 1996 Volume 24, Issue 4 Pages 459-462
Guo Zhongxian

Abstract: An appropriate amount of hair digest or pretreated water sample was mixed with 2 mL mixed masking reagent containing 1% NaF, 2% sodium sulfosalicylate, 2% ethylenediamine and 5% Na2CO3. A 18 µL portion of the solution was injected into a carrier stream of Na2B4O7/NaOH buffer of pH 10.3 (4.5 ml/min), which was mixed with a stream of 0.95 µM reagent stream, containing 0.15% OP, flowing at the same rate. The mixture was transferred to a reaction coil (50 cm) and the absorbance of the resulting complex was measured at 522 nm. The calibration graph was linear from 0.05-1 µg/ml of Hg and the detection limit was 0.016 µg/ml. Recoveries were 97.9-102.7% and RSD (n = 6) was 1.5%. The sample throughput was 100/h. Tolerance levels for thirty six foreign ion species on the determination of 0.8 mg/l of Hg are listed.
Mercury Spectrophotometry

"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

"Determination Of Traces Of Zinc By Flow Injection Spectrophotometry With 2-hydroxy-3-[(4-phenylazophenyl)triazeno]-5-sulfobenzoic Acid"
Fenxi Huaxue 1996 Volume 24, Issue 12 Pages 1472-1472
Guo, Z.X.;Zhang, S.Y.

Abstract: With 0.05 M Na2B4O7/NaOH buffer of pH 10.8 as the carrier stream (5.2 ml/min), ethanolic 0.68 mM reagent/aqueous 4% emulsifier OP (unspecified)/H2O (20:3:77) as the reagent stream (5.2 ml/min) and detection at 520 nm, the calibration graph was linear for 0.072-0.05 mg/l of Zn, with a detection limit of 0.036 mg/l. Masking with NaF/potassium sodium tartrate/sodium sulfosalicylate permitted the tolerated amounts of Al(III), Fe(III), Cd(II) and Hg(II) to be greatly increased. The method was used in the analysis of human hair, rice, flour and tap water, with recoveries of 70.9-100.5%. The results were compared with those obtained by dithizone-extraction spectrophotometry.
Zinc Spectrophotometry Sample preparation Dithizone Extraction

"Simultaneous Determination Of Aluminum And Iron By Flow Injection Stopped-flow Spectrophotometry"
Fenxi Huaxue 1997 Volume 25, Issue 1 Pages 37-40
Zhang, A.M.;Wang, S.H.;Wang, H.S.;Cui, H.

Abstract: Sample was injected into the FIA system over 8 s and flowed at 2.5 ml/min into a carrier stream of 10 mL 0.2 M potassium hydrogen phthalate buffer of pH 5 to merge with a reagent stream containing aqueous 0.036% cetylpyridinium bromide at 2 ml/min. The mixture then flowed through a reaction coil (30 cm long) where it was reacted with 120 µL 0.008% Chrome Azurol S in a reactor (40 cm long). After stopping the flow for 20 s, the absorbance was measured at 620 nm. Al and Fe concentrations were calculated from linear calibration graphs ranging from 0-0.4 and 0-0.8 mg/l, respectively. Only Ni(II) and fluoride interfered. The method was applied to the simultaneous determination of Al(III) and Fe(III) in tap water, tea leaves and flour, with recoveries of 93.1-109% and RSD of 1-3.1%. The sampling frequency was 90 runs/h.
Iron Aluminum Spectrophotometry Stopped-flow Simultaneous analysis Interferences

"Determination Of Fluoride In Tap Water By Electroosmosis Pump Flow Injection - Spectrophotometry"
Fenxi Huaxue 1998 Volume 26, Issue 2 Pages 125-128
He, Y.;Gan, W.;Zhang, M.;Zheng, M.;Zeng, R.;Jin, G.

Abstract: The principle of electroosmosis pump and the characterization of its application in flow injection (FI) system are discussed. Alizarine complex was the colored species.
Fluoride Spectrophotometry Pump Electroosmotic flow Apparatus

"Flow Injection Analysis Of The Sum Of Trace Level Calcium And Magnesium In Water With CPA-I Spectrophotometry"
Fenxi Kexue Xuebao 1998 Volume 14, Issue 2 Pages 55-57
Li Zhiyun, Zhang Wei, Ge Jirong, Ye Song, Ma Huichang

Abstract: In this paper, a wavelength (590 nm) with equal absorption coefficients for calcium and magnesium was discovered using the sensitivity enhancement of alcohol in the reaction system of calcium and magnesium with CPA-I (Chlorophosphonazo-I). Therefore, a flow injection analysis method was established to determined the sum of trace level calcium and magnesium in water with a detection limit of 0.07 µm.cntdot.L-1. The relative standard deviation (RSD) (n=10) for a sample of 10 µm.cntdot.L-1 was ±0.3% with a sample throughput of 120 samples per h. The proposed procedure was applied successfully to the anal. of soft water.
Calcium Magnesium Hardness Spectrophotometry

"Simultaneous Determination Of Cobalt And Iron In Water Samples By FIA Merging Zone Method"
Fenxi Shiyanshi 1992 Volume 11, Issue 3 Pages 17-19
Li, H.;Liu, H.;Zhao, X.

Abstract: Sample (2 ml) is injected and carried with water to mix (or not to mix when values for both Co and Fe are required) with a reagent stream of H2O2 - F- (50 µL) which flows with a carrier stream (of 130 mL of HCl - Na acetate buffer of pH 4.5, 10 mL of 2% ascorbic acid and water to 200 ml) before combining with a stream of 0.013% chromogenic reagent (containing 65 mL of 0.02% 5-(3,5-dibromo-2-pyridylazo)-2,4-diaminotoluene and HCl - Na acetate buffer of pH 3.7 to 100 ml) and a stream of 1.8 M HCl; all streams flow at 2.6 mL min-1 and detection is at 550 nm. Since F- can completely mask Fe3+, Co can then be determined and total Fe and Co can be determined as well, thus allowing the simultaneous analysis of Fe and Co. Recoveries were 98.6 to 104%; coefficient of variation for Co and Fe were 3.2 and 4.2%, respectively. Calibration graphs were rectilinear for 0.1 to 3 ppm of Co and 0.1 to 2.5 ppm of Fe. Most foreign ions did not interfere. The method was used for analyzing tap water and waste water.
Cobalt Iron Spectrophotometry Merging zones Interferences Merging zones Simultaneous analysis Chromogenic reagent

"Continuous Immunochemical Determination Of Pesticides Via Flow Injection Immunoanalysis Using Monoclonal Antibodies Against Terbutryne Immobilized To Solid Supports"
Food Agric. Immunol. 1995 Volume 7, Issue 3 Pages 203-220
Dietrich, M.;Kramer, P.M.

Abstract: Anti-terbutryne mAb were immobilized to polystyrene and glass beads, and the different immobilization techniques were compared for their applicability in FIA. The immobilization methods used were (i) covalent immobilization to glass beads using acetic acid/periodate with subsequent coupling of biotinylated antibodies; (ii) adsorption of avidin to polystyrene beads and coupling of biotinylated antibodies and (iii) covalent immobilization of antibodies to glass beads with glutaraldehyde. Methods (ii) and (iii) were the most effective, and (iii) was found most effective for FIA. The antibodies could be regenerated at least 60 times. The calibration graph was linear from 0.01 µgl (detection limit) to 5 µg/l. The method could be used for monitoring drinking water sources.
Terbutryne Immunoassay Glass beads Immobilized antibody Polystyrene beads

"Analysis Of Anions And Cations In Drinking Water Samples By Capillary Ion Analysis"
Food Chem. 1998 Volume 61, Issue 1-2 Pages 249-254
Bahruddin Saad*, Fen Wei Pok, Amat Ngilmi Ahmad Sujari and Muhammad Idiris Saleh

Abstract: The use of capillary ion electrophoresis (CIE, Waters' tradename: Capillary Ion Analysis, CIA) for the analysis of four anions and four cations in drinking water samples available on the Malaysian market, such as natural mineral water, bottled drinking water and tap water, was investigated. In addition, zam-zam water (an underground water, much sought-after by Muslims and only available in Mekah, Saudi Arabia) was also analyzed. The anions analyzed were chloride, sulfate, nitrate and fluoride while the cations analyzed were potassium, calcium, sodium and magnesium. Results of this determination generally show a low content of anions and high content of calcium and magnesium in natural mineral water and non-detectable amounts of anions and cations in bottled drinking water. Out of the 15 mineral waters of different brands that were analyzed, four brands show anionic and cationic levels almost similar to that of tap water. With the exception of fluoride, an abnormally high level of both anions and cations were detected in all the zam-zam water samples analyzed, as compared to the other drinking waters.
Anions Chloride Sulfate Nitrate Fluoride Cations Potassium Calcium Sodium Magnesium Electrophoresis

"Bioavailability Of Labile Aluminum In Acidic Drinking Water: A Study In The Rat"
Food Chem. Toxicol. 1995 Volume 33, Issue 5 Pages 403-408
A. Wicklund Glynn

Abstract: The bioavailability of labile Al (Allab; Al3+, and monomeric hydroxo and sulfato complexes) in drinking water was studied in the rat. The hypothesis was that Allab in drinking water is more available for absorption in the gastro-intestinal tract than Al complexed in the rat feed. Male Sprague-Dawley rats were exposed to 4 mg Al/litre in acidic drinking water (pH 4-5) and 5 mg Al/kg in the feed for 10 wk. The Al intake of these rats was about twice that in a control group of rats that received Al only in the feed. Both a theoretical speciation calculation and a speciation analysis of the water in a flow injection system showed that more than 98% of the Al in the water was present as Allab. However, intake of this water did not result in increased levels of Al in the bone, liver or brain tissue of the rats. Al speciation in a simulated rat stomach indicated that Allab in drinking water is rapidly complexed by feed constituents as the water enters the acidic milieu of the stomach, resulting in a very low concentration of Allab. The concentration of dissolved Al was also low in comparison to the added amount of labile Al. The possibility of complex formation between Allab and feed components in the gastro-intestinal tract should be taken into account in further studies of the bioavailability of drinking water Al in experimental animals and in humans.
Aluminum, labile Speciation

"Automated Immunochemical Analysis Of Specific S-triazine And Phenylurea Herbicides In Drinking Water Supplies"
Food Technol. Biotechnol. 1998 Volume 36, Issue 2 Pages 111-118
Petra M. Kr&auml;mer

Abstract: Automated immunochemical analysis offers an inexpensive online monitoring or off-line screening of different drinking water sources without extensive sample preparation and without using organic solvents. Two prototype system instruments, one online the other off-line, were studied within the European project, Program Life. Results discussed were performed with the off-line device, where standards and samples are supplied in sep. vials. Automated anal. depends on an extended time of operation without attendants; therefore, all reagents, especially immunoreagents (antibody and enzyme-tracer), should have a stability of at least 14 days. Different stabilization methods were studied. Best stability (at least 14 days) was achieved by adding 0.5% BSA (bovine serum albumin) and 0.5% micro-O-protect, together with storage at 4°C. To reduce buffer salts, which would be discharged to the environment during continuous FIIAA (flow injection immunoaffinity anal.), a comparison of 40 and 4 mM PBS (phosphate buffered saline) as carrier buffer was made. Results showed there was no difference in performance between the 2 carrier buffers. As an example, the system was applied to determine diuron in actual water samples which contained high concentrations of humic substances (9.5 mg/L DOC [dissolved organic carbon]). Samples were collected from groundwater and different water treatment stages of the water supply station in Fuhrberg, Germany, and afterwards spiked with diuron. As a reference method, samples were analyzed by conventional micro-titer plate ELISA, using the same immunoreagents. Determined amounts were generally in good agreement with spiked amts.; FIIAA produced better results.
Herbicides, phenylurea Herbicides, triazine Immunoaffinity Process monitoring Apparatus Instrumentation Optimization Method comparison

"Heavy Toxic Metal Detection. 2. Enhanced Performance Of Lead ChemFET"
Gazz. Chim. Ital. 1997 Volume 127, Issue 4 Pages 227-229
Davini, E.;Barbaro, A.

Abstract: New formulations have been tested for obtaining a polymeric membrane, linked to the surface of an FET and sensitive to lead ions. We were able to detect, for the first time in the literature, lead ion in a real sample (drinking water) down to a concentration of 0.2 mg/l (1 µM). 20 References
Lead(2+) Electrode Field effect transistor Potentiometry Sensitivity

"From FIA To Bio-probes - Biochemical Analytics In Examples Of Application"
GIT Fachz. Lab. 1990 Volume 34, Issue 9 Pages 1045-1046
Bilitewski, U.;Schmid, R.D.

Abstract: A review is presented on the application of online analytical systems (FIA and in situ electrodes) for the enzymatic or immunochemical analysis of e.g., fermentation liquors, drinking water and foodstuffs. (22 references).
Electrode Sensor Review Enzyme

"Biosensor For The Automated Determination Of Pesticides In Potable Waters"
GIT Fachz. Lab. 1991 Volume 35, Issue 10 Pages 1062-NA
Kindervater, R.;Zischkale, F.;Wagner, K.

Abstract: A flow injection analysis system is described, in which the sample is mixed with particles in a magnetic field and which includes a column of immobilized cholinesterase.
Pesticides Sensor Automation Column Immobilized enzyme

"Determination Of Mercury In Water And Waste Water According To DIN 38 406. 12"
GIT Fachz. Lab. 1992 Volume 36, Issue 2 Pages 115-121
Projahn, H.D.;Pohl, B.;Steeg, U.

Abstract: The results of collaborative tests on this standard for the determination of total Hg in water are reported. Each of the 14 participating laboratories analyzed in quadruplicate the following: (a) standards (2 to 5 µg L-1 of Hg) in de-ionized water, (b) standards (0.05 to 0.2 µg L-1 of Hg), (c) biologically clarified waste water with added inorganic and organic Hg, and (d) drinking water with added inorganic and organic Hg. All analyzes in the upper range were by cold vapor AAS with a direct continuous-flow method and in the lower range by cold vapor AAS after amalgamation on an Au contact. Samples containing organic Hg were oxidized with KMnO4 - K2S2O8. All samples were treated with a stabilizing solution (K2Cr2O7 in HNO3) and analyzed as soon as possible after preparation in order to minimize losses. The results were satisfactory, with recoveries (0.155 to 4 µg L-1 of Hg) of 93.7 to 95.7% and overall coefficient of variation in this range of 9.1 to 22.5%.
Mercury Spectrophotometry Standard method Amalgamation

"Determination Of Trace Lanthanum In Natural Waters By A Flow Injection Online Preconcentration ICP System"
Guangpuxue Yu Guangpu Fenxi 1992 Volume 12, Issue 5 Pages 63-66
Fan, S.H.;Fang, Z.L.

Abstract: Sample (3.3 ml) at pH ~7 was applied at 5.5 mL min-1 into a flow injection system for pre-concentration. on a CL-P507 resin column (3 x 0.5 cm) for 35 s then eluted at 1 mL min-1 with 1 M HCl for 20 s; the eluate was mixed in a tube (35 cm x 0.35 mm) before analysis by ICP-AES with measurement at 379.5 nm. Recovery was 90 to 110% with a coefficient of variation of 1.7%. The detection limit was 0.7 µg L-1 of La. A 25- to 30-fold pre-concentration. could be achieved. Sampling frequency was 60 h-1. The method was employed for assay of tap water, polluted water and soil extract.
Lanthanum Spectrophotometry Sample preparation Preconcentration Resin

"Determination Of Trace Molybdenum By Online Ion-exchange Preconcentration With A Flow Injection Inductively Coupled Plasma Atomic-emission Spectrophotometric System"
Guangpuxue Yu Guangpu Fenxi 1993 Volume 13, Issue 5 Pages 73-76
Guo, L.;Zhang, G.L.;Fang, Z.L.

Abstract: Tap water was injected at 5.7 ml/min into a micro-ion-exchange column (3 cm x 3 mm i.d.) packed with Dowex 1 resin (chloride form; 100 mesh) for dual-column online ion-exchange pre-concentration in a FIA system (diagram given) with 1.9 M ammonium chloride/0.4 M ammonium citrate as the eluent at 0.5 ml/min and 60°C over 5 min. The eluate was raised at 0.5 ml/min to the spectrophotometer with Ar as carrier gas (0.68 l/min) for ICP-AES of Mo with measurement at 281.62 nm. The observation height was set at 12 mm and plasma power was at 1.2 kW. Recoveries were 90-110% for 0.2 ng/l of Mo and RSD were 5.3%. An enrichment factor of 50 was achieved at sampling frequency of 12 samples per h. The method was applied to soil after treatment with 0.1 M oxalic acid and 0.175 M ammonium oxalate.
Molybdenum Ion exchange Spectrophotometry Preconcentration
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