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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Waste

Classification: Waste -> water

Citations 254

"Flow Injection Biamperometric Determination Of Chloramine-T In Environmental, Pharmaceutical And Veterinary Samples"
Anal. Chim. Acta 2000 Volume 407, Issue 1-2 Pages 187-192
M. Catalá Icardo, D. Giménez Romero, J. V. García Mateo and J. Martínez Calatayud

Abstract: A flow injection assembly for the determination of chloramine-T is proposed. The sample (213 µl) is inserted into the carrier, de-ionized water flowing at 4.1 mi min-1. This carrier merges with a mixture of potassium iodide and sulphuric acid, and the resulting solution flows to the flow cell through a reactor 66 cm long. The chloramine-T oxidises the iodide to tri-iodide. The resulting iodide/iodine ratio is biamperometrically tested. The calibration graph is linear up to 65 µg mL-1 chloramine-T; the limit of detection is 0.5 µg ml-1; the relative standard deviation (r.s.d) of the calibration slope is 2.8% for a series of eight independent calibrations. The RSD of a series of 74 peaks for 40 µg mL-1 chloramine-T) is 0.8%, and the sample throughput 220 h-1. Few foreign substances interfered. The method is applied to pharmaceutical, veterinary and waste water samples.
Chloramine T Biamperometry Clinical analysis Interferences Preconcentration

"Simultaneous Spectrophotometric Determination Of Phosphate And Silicate By A Stopped-flow Sequential Injection Method"
Int. J. Environ. Anal. Chem. 2000 Volume 77, Issue 3 Pages 185-202
Mas Torres, F.;Munoz, A.;Estela, J.M.;Cerda, V.

Abstract: A sequential injection analysis method for the simultaneous spectrophotometric determination of phosphate and silicate has been developed. The method is based on the different reaction rates of the heteropolymolybdate formation reactions. Concentrations within the range 0.026-0.485 mmol P L-1 and 0.125-2.848 mmol Si L-1 have been determined at a frequency of 30 samples per hour. An RSD of 2.1% was obtained for 0.162 mmol P L-1 and of 1.1% for 1.424 mmol Si L-1. The method was found to be suitable for the determination of phosphate and silicate in wastewater.
Phosphate Silicate Spectrophotometry Sequential injection Kinetic Simultaneous analysis

"Rapid Sr-90/Y-90 Determination In Water Samples Using A Sequential Injection Method"
Appl. Radiat. Isot. 2000 Volume 53, Issue 1-2 Pages 139-144
J. J. Mateos, E. Gómez, F. Garcias, M. Casas and V. Cerdà

Abstract: We have developed a semiautomatic procedure based on a sequential injection method for Sr-90/Y-90 determination that allows their radiochemical separation in about 30 min. The method has been tested using 90Sr/90Y solutions with activities lower than 12 Bq. The source is eluted in a pH = 6.5 medium through a MnO2-impregnated cotton filter, where Y-90 is pre-concentrated in preference by adsorption. 90Y is extracted from the column with hydroxylamine, some Sr-90 in the leached solution has also been found. After the radiochemical separation, the total β-activity of the leached solution has been determined using a low background α-β proportional counter and. assuming the presence of Sr-90 and Y-90 at t = 0, the solution of the Bateman equations allows the initial concentration of both isotopes to be obtained. We have verified that the addition of some ions usually found in water samples (Cl-, HCO3-, NO3-, SO42-, Ca2+, Mg2+) does not interfere with the yield of the radiochemical process, (90±10)%. The method has been applied to Sr-90/Y-90 determination in mineral waters, and even in thermal waters, where the salt concentration can be about 3500 mg/L, the radiochemical yield remains greater than 80%.
Strontium-90 Yttrium Sequential injection Optimization Interferences Filter

"Preconcentration And Speciation Of Chromium In Waters Using Solid-phase Extraction And Atomic Absorption Spectrometry"
Talanta 2000 Volume 51, Issue 3 Pages 531-536
D. M. Adriá-Cerezo, M. Llobat-Estellés and A. R. Maurí-Aucejo

Abstract: A method for the pre-concentration and speciation of chromium was developed. After formation of an anionic compound with ethylenediaminetetraacetic acid (CrY-), Cr (VI) and Cr (III) are retained on a strong anionic phase (SAX) and controlled elution with 0.5 M NaCl permits their speciation. The retention and elution conditions were optimized, and interferences due to the presence of other ions such as Mg(II), Mn(lI), Sn(II), Fe(III), Ba(II), Al(III), Ca(II), chloride, iodine, bromide, fluoride, sulfate, phosphate, bicarbonate and nitrate were studied. The detection limits were 0.4 µg L-1 and 1.1 µg L-1 for Cr(III) and Cr(VI), respectively, and reproducibility was 9%. The results obtained for speciation of chromium by the proposed method in wastewaters are in agreement with the values obtained by a reference method for a 95% confidence level.
Chromium(III) Chromium(VI) Spectrophotometry Speciation Preconcentration Interferences Optimization Column Resin Standard method Method comparison

"Substance-specific Detection And Pursuit Of Non-eliminable Compounds During Biological Treatment Of Waste Water From The Pharmaceutical Industry"
Waste Manage. 1999 Volume 19, Issue 2 Pages 111-123
H. Fr. Schröder

Abstract: Up to now comprehensive examination and assessment of the elimination behavior of many different pollutants in biological waste water treatment failed above all because of limited possibilities to pursue polar organic compounds of anthropogenic and biogenic origin. In this case the behavior of waste water constituents during the treatment of waste water from the pharmaceutical industry was studied with the help of mass-spectrometric detection (MS). After complete as possible extraction and concentration by liquid/liquid and solid phase extraction (SPE) from samples of influent and effluent of a pilot plant, substance-specific determination and identification was done after chromatographic separation and with the help of mixture analysis, respectively. Separation by gas chromatography coupled with MS was applied to pursue the organic compounds, which are volatile without decomposition, during the waste water treatment process. Flow injection analysis (FIA) bypassing the analytical column combined with soft-ionizing interfaces served for screening of the polar compounds. Then they were separated by liquid chromatographic methods to recognize changes in the qualitative and quantitative compound spectrum. Mixture analysis by FIA combined with tandem mass spectrometry (FIA/MS/MS) was used for identification of the pollutants without previous chromatographic separation. A laboratory-made daughter ion library helped to identify some of the poorly eliminable pollutants detected. The presentation of the monitoring procedures applied was made in such a way that the treatment results were visually recognizable. Due to the use of timesaving FIA/MS, this method may serve for substance-specific monitoring of the treatment of possibly problematic waste waters.
Organics, polar Mass spectrometry

"The Properties Of Chromatomembrane Cells In Flow Systems Coupled To Gas Chromatography - Analysis Of Volatile Organic Compounds"
Talanta 2000 Volume 52, Issue 1 Pages 123-128
Carsten Bloch, Jürgen Simon, Leonid N. Moskvin and Oleg V. Rodinkov

Abstract: The economical use of modern analytical instrumentation requires an online-coupling of efficiently working flow-systems which automate both sampling and sample pretreatment. Whenever extraction and pre-concentration procedures are necessary the application of chromatomembrane cells proved to be very worthwhile. On this occasion the analyte exchange takes place inside a block of biporous PTFE wherein the two immiscible phases come into contact with each other. A special enclosure enables water and the extracting nitrogen to flow independently through that block. In case of gaseous extractants the behavior of the biporous PTFE and its mechanical parameter have to be investigated precisely in order to overcome the special problems of trace analysis in gases. The gas-chromatographic detection of volatile organic compounds (VOCs) requires a discussion on the effects of gas-sorption and the kinetics of equilibration which should be taken into consideration for using the chromatomembrane cell as an extractor from waste water. The investigation realizes at least that a quick pretreatment is made possible and, however, sample sizes decrease remarkably in comparison with competing methods as head space analysis or purge and trap technique. The application of chromatomembrane cells permits reasonable accuracies with a limit of detection on the ng/l level.
Chloroform Benzene Dichloromethane Toluene Cyclohexane Diethylether Ethyl acetate Hexane GC Extraction Preconcentration Chromatomembrane Volatile generation

"Spectrophotometric Determination Of Thiocyanate By Sequential Injection Analysis"
Anal. Chim. Acta 2000 Volume 403, Issue 1-2 Pages 279-286
J. F. van Staden and A. Botha

Abstract: A sequential injection analysis (SIA) system was developed for the spectrophotometric determination of thiocyanate as Fe(SCN)(2+). The physical parameters (flow rate, sample and reagent volumes, holding coil and reaction coil internal diameter and length) which influence dispersion in a SIA system were optimized. The effect of the reagent concentration and nitric acid concentration tin the reagent solution and carrier stream, respectively), were also studied. Reagent consumption was effectively reduced by introducing the reagent as a zone into the nitric acid carrier stream, compared to flow injection analysis where the reagent itself is the carrier stream. The system is fully computerized and able to monitor thiocyanate in samples at 24 samples per hour with a relative standard deviation of <1.20% for samples and standards with thiocyanate concentrations above 10.0 mg L-1. The calibration graph is linear from 2.0 to 150.0 mg L-1 with a 3s detection limit of 1.1 mg L-1. The system has been applied to the determination of thiocyanate in process solutions and waste waters.
Thiocyanate ion Spectrophotometry Sequential injection Process monitoring Optimization Computer

"A UV Spectroscopic Method For Monitoring Aromatic Hydrocarbons Dissolved In Water"
Anal. Chim. Acta 2000 Volume 422, Issue 2 Pages 187-198
F. Vogt, M. Tacke, M. Jakusch and B. Mizaikoff

Abstract: An enhanced UV spectrometric method is applied to trace measurements of aromatic hydrocarbons dissolved in water. This approach gains selectivity and sensitivity by the use of optically generated first and second derivatives of transmission spectra. The augmented spectroscopic technique is combined with chemometric algorithms like principal component regression or partial least squares which are used for calibration of the spectrometer and quantitative evaluation of spectra. Laboratory measurements were performed on mixtures containing up to five substances, i.e. benzene, toluene, ethylbenzene, the three xylene isomers, chlorobenzene, and gasoline. Due to the difficulty of preparing precisely defined calibration and test samples of these very volatile compounds, a novel mixing device was developed and is presented. From these first investigations it can be estimated that the detection limits are down to ~10 µg analyte per liter of water by using a 10 cm absorption pathlength and a few minutes measurement time.
Hydrocarbons, aromatic Benzene Chlorobenzene Ethylbenzene Toluene 4-Xylene 2-Xylene 3-Xylene Spectrophotometry Spectroscopy Sequential injection Chemometrics Optimization

"Comparing Different Approaches For Assembling Selective Electrode For Mercury Ions"
Proc. Electrochem. Soc. 2001 Volume 18, Issue 1 Pages 284-292
I. Turyan, M. Atiya, G. Shustak, and D. Mandler

Abstract: Different approaches for increasing the sensitivity, selectivity and stability of a voltammetric probe for mercury ions have been investigated. These involve the application of adsorbed monolayers of a host molecule, i.e., 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane (Kryptofix-222) and thin polymeric films. The stability, reproducibility and durability of the sensors in the analysis of Hg2+ from different sources have been examined and compared. We found that a monolayer of the macrocyclic ligand, which is capable of forming a strong and selective complex with the mercury, is superior to polymeric films in terms of sensitivity and ease of regeneration. On the other hand, the stability and durability of polymeric films, in which Kryptofix-222 is incorporated, will eventually dictate their use as preferred interfaces for repetitive analyzes especially in flow analysis systems. An application of a polymer-Kryptofix-222 modified electrode for monitoring mercury in a bioremediation pilot has been examined using an automatic sequential-injection stripping analysis (SISA) system. [Conference Paper; 4 Refs]
Mercury Voltammetry Sequential injection

"A New Device For Improving Sensitivity And Stabilization In Flow Injection Analysis"
Anal. Chim. Acta 1978 Volume 97, Issue 2 Pages 427-431
H. Bergamin F, B. F. Reis and E. A. G. Zagatto

Abstract: In flow injection anal., an aqueous sample is injected into a continuous moving carrier stream of reagent. If the sample injection is done by forcing the liquid into the carrier stream, the regularity of the flow is disturbed momentarily. There is a temporary difference in mixing ratios at those points in the manifold where 2 streams meet. This can cause a change in the blank values. To minimize these changes, while increasing sensitivity, a confluence manifold was used for the spectrophotometric and/or turbidimetric determination of NO2-, SO42-, and Cl- in natural waters. An injection pulse dampener is described and is recommended when flow injection confluence systems are employed for anal. of very dilute samples.
Chloride Chlorine Chlorate ion Perchlorate Nitrite Sulfate Spectrophotometry Turbidimetry Apparatus Pulse dampener

"A Detailed Study Of Sample Injection Into Flowing Streams With Potentiometric Detection"
Anal. Chim. Acta 1978 Volume 98, Issue 2 Pages 193-203
Zs. Feh&eacute;r and G. NagyK. T&oacute;th and E. Pungor

Abstract: A new method developed by combining manual or coulometric injection into flowing streams and potentiometric detection is described. The potential-time curves obtained in a flow-through detector as a result of single injections are handled theoretically and examined practically. The effects of experimental parameters, concentrations and flow rates on the signal are discussed. A systematic survey of the potential use of the technique in analysis is given. Species can be determined easily either in the flowing stream or in the injected sample. Some applications in pharmaceutical and other types of analysis are listed, and the main advantages of the technique are summarized.
Bromine Chlorine Cyanide Thiocyanide Indium Enzyme, cholinesterase Uric acid Enzyme, urease Glucose Enzyme, glucose oxidase Urea Nitrogen, urea Potentiometry Coulometric injection

"Flow Injection Analysis Of Calcium In Serum, Water And Waste Water By Spectrophotometry And By Ion-selective Electrode"
Anal. Chim. Acta 1978 Volume 100, Issue 1 Pages 151-165
E. H. Hansen, J. Rika and Animesh K. Ghose

Abstract: The flow injection technique is a fast, reliable, and sensitive method for the determination of Ca in various aqueous as well as serum samples; spectrophotometric or potentiometric detection can be used. At sampling rates of 100-10 samples/h, with 30 µL sample injections, high reproducibility of measurement and low reagent consumption are achieved in both methods. In the spectrophotometric method (with o-cresolphthalein complexon), the anal. readout is available within 12 s after sample injection at a total reagent consumption of 0.75 mL/anal. The potentiometric measurement of the Ca activity in serum is placed on a reliable basis by alternating measurements of serum samples and aqueous standards without incurring any nonreproducible changes in potential between aqueous and serum solutions This permits the simultaneous determination of pH and pCa, the anal. readout being available within 3 s of sample injection. The good agreement between the results obtained with the flow injection method and those attained by atomic absorption and EDTA titrns. as well as pCa stat-measurements show that the new methods are potentially suitable for routine anal.
Calcium pH Spectrophotometry Electrode Potentiometry Method comparison

"An Injection Method For The Sequential Determination Of Boron And Several Metals In Waste-water Samples By Inductively-coupled Plasma Atomic Emission Spectrometry"
Anal. Chim. Acta 1979 Volume 109, Issue 1 Pages 73-83
J. A. C. Broekaert and F. Leis

Abstract: Boron and nine metals (Ba, Cd, Cu, Fe, Mn, Mo, Ni, Zn) can be determined in waste waters of medium and high salt concentration by inductively-coupled plasma atomic emission spectrometry. An injection method was applied in order to achieve analysis times of about 1 min per determination, and to allow trace analysis in solutions having salt concentrations up to 20 mg mL-1, when a Meinhard nebulizer is used with a low-power argon plasma. When 500-l aliquots are injected and the peak heights of the amplified photomultiplier signals are measured, the detection limits for the elements tested range from 0.05 to 0.4 µg mL-1. Matrix effects caused by sodium nitrate (20 mg mL-1) are less than 20%, provided that a peristaltic pump is used for feeding the nebulizer. Matrix effects can be decreased by using simultaneous background measurement. The plasma-injection method is applicable to boron and metals in the range 0.05-20 µg mL-1.
Boron Barium Cadmium Copper Iron Manganese Molybdenum Nickel Zinc Spectrophotometry

"Continuous Monitoring Of Total And Inorganic Mercury In Wastewater And Other Waters"
Anal. Chim. Acta 1982 Volume 140, Issue 1 Pages 179-185
Masashi Goto, Takahiro Shibakawa, Tomomitu Arita and Daido Ishii

Abstract: An automated continuous monitoring system for the determination of total as well as inorganic mercury by cold-vapor atomic absorption spectrometry is described. The method uses continuous flow digestion, reduction and extraction in small bore tubes at slow flow rates, and is suitable for use in the analysis of wastewater and natural waters. A detection limit of 0.1 ppb is obtained when a specially designed, complete gas-liquid separator is used with a condenser circulated with ice-chilled water for removing water vapor, and an 8-l flow cell for detection. The response times for the determination of inorganic and total mercury are about 3 and 5 min, respectively. The amount of reagents required is about one-tenth of that in conventional Auto-Analyzer methods.
Mercury Mercury(II) Spectrophotometry Computer

"Determination Of Chemical Oxygen Demand In Wastewaters With Dichromate By Flow Injection Analysis"
Anal. Chim. Acta 1982 Volume 141, Issue 1 Pages 301-309
Takashi Korenaga and Hisa Yoshi Ikatsu

Abstract: A simple method is described for the continuous determination of chemical oxygen demand (COD) in wastewater samples by flow injection analysis. Samples are injected into a water stream which merges with an acidic dichromate carrier solution. After reaction in a PTFE coil at 120°C, absorbances are measured at 445 nm. D-Glucose is satisfactory as a standard substance for COD in a variety of wastewaters. A sampling rate of 15 samples per hour can be achieved, and the detection limit and precision are 5 mg L-1 as COD and 0.4%, respectively. Chloride concentrations of ≥100 mg L-1 interfere slightly unless silver and/or mercury salts are added. COD values for various wastewater samples correlate well with those obtained by standard methods using dichromate or permanganate.
Chemical oxygen demand Spectrophotometry

"Flow Injection Analysis With Tensammetric Detection For The Determination Of Detergents"
Anal. Chim. Acta 1984 Volume 156, Issue 1 Pages 71-76
M. Bos, J. H. H. G. van Willigen and W. E. van der Linden

Abstract: The sample (60 µL of, e.g., aqueous production-control solution or sewage) is injected into a carrier stream (5 mM in a surfactant), which is subsequently mixed with 0.1 M Na2SO4 and passed into a detector cell equipped with a mercury-coated gold electrode, an uncoated gold counter-electrode and a silver - AgCl reference electrode. The change in capacitance of the electrical double layer of the working electrode is measured at -0.85 V (except for benzalkonium chloride, for which the applied potential is -0.40 V). Calibration graphs are non-linear and are best approximated by use of polynomial or cubic spline functions. The method is applicable to both ionic and non-ionic surfactants in the range 10 to 100 µM, with relative errors of ~±4%. Sixty samples can be analyzed in 1 h.
Benzalkonium chloride Surfactants Electrode Electrode Sensor Voltammetry

"Evaluation Of A Dialysis Probe For Continuous Sampling In Fermentors And In Complex Media"
Anal. Chim. Acta 1984 Volume 163, Issue 1 Pages 135-141
C. F. Mandenius, B. Danielsson and B. Mattiasson

Abstract: The steam-sterilizable probe described yields samples suitable for, e.g., HPLC, flow injection analysis or enzyme calorimetry. The analyte is transferred from the sample to a flowing stream by passage through a dialysis membrane that is protected from fouling by the sample mixture by means of a magnetic stirring-bar rotating close to the membrane surface.
Dialysis Apparatus Membrane

"Rapid Determination Of Sulfide In Waste Waters By Continuous-flow Analysis And Gas Diffusion And A Potentiometric Detector"
Anal. Chim. Acta 1984 Volume 163, Issue 1 Pages 293-297
K. Brunt

Abstract: The system is based on a flow-through gaseous diffusion unit and potentiometric determination with a S2--selective electrode. In the range 0.5 to 600 ppm of S2-, the mean response is 30.2 mV per decade. The sampling rate is ~15 h-1, and the efficiency of transfer across the PTFE membrane is 48%. At S2- concentration. <50 ppm, the results obtained agreed well with those by a distillation method. Apparent losses at higher concentration. in the proposed method are ascribed to incorrect sample storage, problems of which are discussed.
Sulfide Electrode Potentiometry Gas diffusion Teflon membrane

"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 Micro Amounts Of Cationic Polymeric Flocculants By Flow Injection Analysis"
Anal. Chim. Acta 1985 Volume 174, Issue 1 Pages 369-373
Kyoji T&ocirc;ei and Takahisa Zaitsu, Chiaki Igarashi

Abstract: The flocculants Cat-Floc [poly(diallyldimethylammonium chloride); I] and Eba-Growth C104G [poly(2-methacryloxyethyltrimethylammonium chloride); II] were determined with the anionic 4-hydroxy-3-(2-hydroxy-3-phenylcarbamoyl-1-naphthylazo)benzenesulfonic acid at pH 10 and 680 nm. The calibration graphs were rectilinear for up to 20 mg l-1, although I required the presence of KNO3. The coefficient of variation (n = 20) for I was 1.2% at a level of 10 mg l-1. Sample throughput was 60 h-1. The proposed method was applied to the determination of II in three samples of treated waste water to give results in good agreement with those obtained by colloid titration. A double plunger pump was used in the flow injection analysis system.
Flocculants Spectrophotometry

"Rapid Determination Of Chemical Oxygen Demand In Waste Waters And Effluents By Flow Injections Analysis"
Anal. Chim. Acta 1986 Volume 179, Issue 1-3 Pages 267-278
J. M. H. Appleton and J. F. Tyson, R. P. Mounce

Abstract: The reagent stream containing K2Cr2O7 - H2SO4 is merged with a stream of water into which the sample is injected. After reagent and sample are mixed the K2Cr2O7 is reduced in a reactor and the absorbance of the Cr(III) produced is measured at 445 nm. Bivalent Hg is added to prevent interference by Cl-, and Ag2SO4 to catalyse the oxidation of n-alcohols and acids. The results for 11 samples agree well with those obtained by a standard method; a high-pressure system and 50-m manifold are not needed.
Chemical oxygen demand Spectrophotometry Interferences Tecator Standard method Method comparison

"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

"Spectrophotometric Determination Of Total Cyanide In Waste Waters In A Flow Injection System With Gas Diffusion Separation And Preconcentration"
Anal. Chim. Acta 1987 Volume 198, Issue 1 Pages 25-36
Zhaohai Zhu and Zhaolun Fang

Abstract: The rapidity of the cited determination was improved by use of the unstable red intermediate product of the reaction of CN- with isonicotinic acid(I) and 3-methyl-1-phenyl-2-pyrazolin-5-one(II), instead of the blue final product. The pH of waste water samples was adjusted to 11.5 to 13.0 before being merged with HCl containing 1,10-phenanthroline to give a pH of 6.4 to 7.4, and reaction at 60°C in a PTFE coil. The liberated HCN diffused through a PTFE separator membrane and was absorbed by NaOH solution This pre-concentrated solution was injected into NaOH carrier, merged with chloramine T and I - II reagents downstream, and the spectrophotometric peaks were recorded at 548 nm. For a 2 mL sample and a pre-concentration. factor of 3.5, the detection limit was 6 ng mL-1. At 0.5 µg mL-1, the coefficient of variation was 1.4% (n = 22). The phenanthroline minimized the interference from most metal ions except Co(II).
Cyanide, total Spectrophotometry Interferences Gas diffusion Heated reaction Preconcentration Tecator

"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 Microcalorimetry In Monitoring Biological Activity Of Aerobic And Anaerobic Wastewater-treatment Processes"
Anal. Chim. Acta 1988 Volume 213, Issue 1 Pages 165-176
Carmel Jolicoeur, Thi Cong To and Andr&eacute; Beaubien, R&eacute;jean Samson

Abstract: A flow microcalorimetric system which is compatible with the experimental conditions of industrial processes was used to monitor the biological activity of wastewater-treatment systems. Two industrial wastewater-treatment processes were investigated: an activated-sludge (aerobic) treatment of a textile factory effluent and a methane fermentation (anaerobic) treatment of effluents from a cheese factory. In both types of system, the heat flux resulting from metabolic reactions during bacterial degradation of organic substances in the effluent could be measured adequately. Depending on the measurements selected, the calorimetric data could be used to monitor the bacterial activity in the bioprocess, or the effluent degradability or toxicity, or the overall content of degradable substrates in the effluent (loading). The non-invasive measurement of heat flux enabled continuous or semi-continuous on-line monitoring of these biological processes. The response time of the flow calorimetric unit is of the order of minutes, thus yielding process data with minimal delay. These data enable rapid intervention to optimize process parameters (e.g., to control the inlet flow rate or dilution, divert or dilute toxic contaminants, etc.).
Activity, biological Calorimetry

"Rapid Spectrophotometric Determination Of Total Phosphorus In Industrial Wastewaters By Flow Injection Analysis Including A Capillary Digestor"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 229-237
M. Aoyagi, Y. Yasumasa and A. Nishida

Abstract: Sample solution in water (as carrier) merged with oxidizing agent (K2S2O8 in H2O) before passing to a digestion unit consisting of 10 m of PTFE tubing holding 10 m of platinum wire (0.2 mm diameter) wound round an aluminum bobbin and heated to 160°C. The solution then mixed sequentially with reducing agent (aqueous 5% Na2S2O3) and color-forming reagent [aqueous malachite green (C. I. Basic Green 4) and (NH4)6Mo7O24.4H2O in ~15% H2SO4] and the absorbance was measured at 650 nm. Calibration graphs were rectilinear for up to 500 ng mL-1 of P and the determination limit was 2 ng mL-1. The coefficient of variation (n = 5) at 200 and 2 ng mL-1 were 0.3 and 6.0%, respectively. Recoveries were quantitative. The method was applied to determine P in industrial waste water and seawater; results agreed with those from the standard procedure.
Phosphorus Spectrophotometry Sample preparation Calibration Catalysis Online digestion Heated reaction Standard method

"Determination Of Total Phosphorus In Waters With Amperometric Detection By Coupling Of Flow Injection Analysis With Continuous Microwave Oven Digestion"
Anal. Chim. Acta 1990 Volume 236, Issue 2 Pages 345-350
S. Hinkamp and G. Schwedt

Abstract: In the manifold (illustrated) of a FIAstar 5020 flow injection analyzer., the sample is injected into a carrier stream of 5 mM H2SO4 (pH 2), which is mixed with 0.06 M HClO4 as decomposing solution before passing through a coil within a microwave oven operated at 650 W. The stream is passed through a gas diffusion unit to remove bubbles before merging with acidic molybdate solution [10 g L-1 of (NH4)6Mo7O24.4H2O and 35 mL L-1 of concentrated H2SO4] and reaction in a coil. The product was reduced to molybdenum blue in an amperometric detector incorporating a vitreous-carbon electrode in wall-jet configuration maintained at +0.26 V vs. Ag - AgCl (3 M KCl). Response based on peak height was rectilinear up to 30 mg L-1 of P, and the detection limit was 0.1 mg L-1 in standard solution The coefficient of variation (n = 5) was 3% at 5 mg L-1 of P. The method gave recoveries ranging from ~63% for pyrophosphate to 91 to 98% for various organic P compounds added to domestic waste water.
Phosphorus Amperometry Electrode Sample preparation Gas diffusion Tecator Microwave Online digestion

"Monitoring And Control Of Biological Removal Of Phosphorus And Nitrogen By Flow Injection Analyzers In A Municipal Pilot-scale Waste-water Treatment Plant"
Anal. Chim. Acta 1990 Volume 238, Issue 1 Pages 191-199
K. M. Pedersen, M. K&uuml;mmel and H. S&oslash;eberg

Abstract: The flow injection system monitors the concentration. of NH4+, NO3- and PO43- in four places: in the inlet, in the outlet of the anaerobic pretreatment tank, in one of the aeration tanks and in the outlet of the plant. Sampling is carried out via a cross-flow filter system, based on an ultra-filtration membrane. The analyzer.s employ highly pulsating, single-piston LC pumps. Synchronization of injection time and pump pulses eliminates the need for pulse-damping devices and ensures high reproducibility. The chemical methods are based on classical colorimetric methods. Design emphasis is on long-term stability, low reagent consumption and minimum maintenance.
Nitrogen Phosphorus LC Spectrophotometry Filter Membrane Pulse dampener Reagent consumption

"Simultaneous And Rapid Enzymic Determination Of Propylene Oxide [methyloxiran] And Propane-1,2-diol With Flow Injection Analysis"
Anal. Chim. Acta 1991 Volume 252, Issue 1-2 Pages 145-151
U. Spohn* and K. H. Mohr, K. Reichwald and I. Rapthel

Abstract: A flow injection procedure for the determination of methyloxiran (I) and propane-1,2-diol (II) in waste water was developed. II was determined with use of immobilized glycerol dehydrogenase and fluorimetric detection of the NADH produced. From 0.05 to 2.5 mM II could be determined with a sampling rate of 40 to 50 h-1. I was hydrolyzed to II before determination. An automatically controlled flow injection set-up may allow the simultaneous determination of I and II.
Methyloxiran 1,2-Propandiol Fluorescence Immobilized enzyme Simultaneous analysis

"Gas Permeation And Preconcentration In The Flow Injection Determination Of Acid-available Cyanide In Waste Water"
Anal. Chim. Acta 1992 Volume 259, Issue 1 Pages 45-52
Vlastimil Kub&aacute;

Abstract: The optimization of a method involving oxidation of CN- to CNCl and chromogenic reaction with isonicotinate - 3-methyl-1-phenyl-2-pyrazoline-5-one (I) is described, and a flow injection system for application to waste water samples is illustrated. The sample is mixed with 0.1 M H3PO4, and the HCN liberated passes through a silicone rubber membrane in a gas permeation unit into a stream of 25 mM NaOH. This solution is sequentially mixed with 0.1% chloramine T solution in 0.25 M phosphate buffer of pH >8 and with 0.24 M Na isonicotinate - 1 mM I, and the absorbance of the blue final product is measured at 544 nm. Most interference, including that of SCN-, is avoided by the gas permeation technique. With pre-concentration. for 2.5 min in the permeation unit, the detection limit was 3 µg L-1 of CN-. A method for the determination of CN- is based on the reaction with Na isonicotinate-3-methyl-1-phenyl-2-pyrazolin-5-one. A reaction mechanism is proposed. The method allows a fast and sensitive determination.
Cyanide Spectrophotometry Optimization Silicone membrane Gas diffusion Preconcentration Interferences

"Flow Injection Determination Of Cyanide By Detecting An Intermediate Of The Pyridine - Barbituric Acid Chromogenic Reaction"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 247-252
Huichang Ma* and Jingfu Liu

Abstract: A kinetic study of the reaction between CN- and pyridine - barbituric acid (I) reagent is described; the intermediate product reaches its max. absorbance (at 494 nm) within 35 to 40 s and, at CN- concentration. 0.1 µg mL-1, exhibits absorbance higher than that of the final product (at 580 nm). An optimized procedure is described in which the sample solution is merged with a mixture of 0.5 M NaH2PO4 - NaOH buffer solution of pH 5.9 and aqueous 0.5% chloramine T, and a solution containing 4.8% of I, 24% (v/v) of pyridine and 4.8% (v/v) of HCl is injected into the resulting stream (which contains CNCl). The calibration graph is rectilinear for up to 4 µg mL-1 of CN- and the detection limit is 20 ng mL-1. The sampling rate is 60 h-1. Interference is caused by Co, Hg(II), Ni, Cu(II), SCN-, I- and formaldehyde. The method was used to determine free CN- in natural and waste water samples without pre-treatment. An unstable intermediate product with peak absorbance at 494 nm was found in the reaction of cyanide with pyridine-barbituric acid reagent. The intermediate was applied to the determination of cyanide by reagent-injection flow injection analysis The calibration graph was linear over the range of 0-4 µg mL-1 cyanide and the detection limit was 20 ng mL-1 cyanide; the relative standard deviation at 1.0 µg mL-1 was 0.6% (n = 16) and the sampling rate was 60 h-1. Interference studies showed that the main interferents are Co2+, Ni2+, SCN-, I- and formaldehyde. The proposed method was applied successfully to determine free cyanide in natural and wastewater samples.
Cyanide, free Spectrophotometry Chromogenic reagent Kinetic Interferences

"Determination Of Chloride Ion Concentration In Natural And Waste Waters By Flow Injection Analysis With A Silver Chloranilate Reaction Column"
Anal. Chim. Acta 1992 Volume 270, Issue 1 Pages 217-221
Fumio Sagara*, Tetsuya Tsuji, Isao Yoshida, Daido Ishii and Keihei Ueno

Abstract: A carrier solution comprising ethanol - water - 0.1 M Na acetate buffer of pH 5.57, (5:4:1) was pumped into the flow system at 2.0 mL min-1. A 100 µL portion of sample water - ethanol - buffer (4:5:1) was injected and the mixture was passed through a cation-exchange column (5 cm x 4.61 mm) of Muromac 50W-X 4 (100 to 200 mesh; NH4+ form). The eluate was treated in a reaction column (same size) packed with Ag chloranilate powder connected to a spectrophotometric detector set at 530 nm. The calibration graph was rectilinear from 2 to 20 µg mL-1 of Cl-. Interferences from anions were negligible. When applied to the analysis of natural and waste waters, the Cl- could be determined in 2 min. The results agreed well with results obtained by a standard manual method. Cl- in natural water and wastewater was determined by flow injection analysis using a column packed with Ag chloranilate powder. EtOH-water-0.1 M Na acetate buffer (pH 5.57) (5+4+1, v/v/v) was used as the carrier at a flow rate of 2 mL/min. The chloranilate ion concentration, which corresponds to the Cl- concentration, in the carrier from the reaction column was monitored by a spectrophotometric detector at 530 nm. Interferences from multi charged cations were eliminated with the combined use of a cation-exchange column inserted in the upper stream of the reaction column. Interferences from anions were negligible. Cl- in natural water and wastewaters (1-20 µg/mL) could be determined rapidly (1 sample/2 min) with high reproducibility. The results agreed well with those obtained by the standard manual method.
Chloride Spectrophotometry Muromac Method comparison Interferences Solid phase reagent Indirect

"Determination Of Chemical Oxygen Demand By A Flow Injection Method Using Cerium(IV) Sulfate As Oxidizing Agent"
Anal. Chim. Acta 1993 Volume 272, Issue 2 Pages 237-244
Takashi Korenaga*, Xiaojing Zhou, Kimiko Okada and Tosio Moriwake, Sumio Shinoda

Abstract: A flow injection system (diagram given) for the automated measurement of COD of waste water is described. Cerium(IV) sulfate was used as oxidizing agent; the fall in Ce(IV) absorbance on reaction with the sample provided a sensitive and reproducible signal. For a standard sample comprising L-glutamic acid and lactose (5:1), the detection limit was 0.5 mg L-1 COD with a coefficient of variation of 0.6%. For 50 µL samples injected at a rate of 20 hr-1, the linear range was 0.5 to 130 mg L-1 COD. Chloride was tolerated up to 30 g L-1 without the need to use masking agents.
Chemical oxygen demand Spectrophotometry Interferences

"Determination Of Nitrogen In Water: Comparison Of A Continuous-flow Method With Online UV Digestion With The Original Kjeldahl Method"
Anal. Chim. Acta 1993 Volume 276, Issue 2 Pages 287-293
Hennie Kroon*

Abstract: The water sample was mixed with K2S2O8 and Na2B4O7 buffer solution in a Skalar continuous-flow system and exposed to UV radiation. The NO3- formed was reduced with Cu-activated cadmium to NO2-, which was then treated with sulfanilamide and N-(1-naphthyl)ethylenediamine before absorbance measurement at 540 nm. Influents and effluents from sewage treatment plants were investigated, as well as surface waters and solution of (NH4)2SO4, glutamic acid, hexamine, urea and nicotinic acid. The coefficient of variation obtained at levels of 2 mg L-1 of N and up to 30 mg L-1 of N were 5 to 10% and 1.5 to 5%, respectively. No significant differences were found between results obtained by this method for surface and waste waters and those obtained by the conventional Kjeldahl method. Unlike the Kjeldahl method, the proposed method is suitable for waste waters of high NO3- content.
Nitrogen Spectrophotometry Sample preparation Method comparison Reduction column UV reactor Photochemistry Kjeldahl

"Comparative Studies Of The Determination Of Cyanide At Low Concentration Levels In Waste Waters"
Anal. Chim. Acta 1993 Volume 283, Issue 2 Pages 755-761
P. C. do Nascimento and G. Schwedt

Abstract: Off-line methods were based on the formation of a stable Ni-cyano complex in ammoniacal solution and subsequent determination by spectrophotometry, polarography or indirect AAS. The absorption spectrum of the Ni-cyano complex exhibited a maximum at 267 nm and Beer's law was obeyed over a wide range. The height of the polarographic wave at -1.35 V vs. Ag/AgCl was proportional to the cyanide (I) concentration in ammoniacal solution using a three electrode apparatus (Hg-dropping electrode, Ag/AgCl, vitreous C electrode), a drop time of 0.8 s per drop, a scan rate of 20 mV/s, a current range of 0.25 nA/mm and a pulse amplitude of 50 mV. For the indirect AAS method, the Ni-cyano complex was extracted into butanol and Ni was determined in the organic phase at 232 nm with an air-acetylene flame. The online determination of I by FIA, was performed by injecting the sample into a 0.01 M NaOH/0.01 M KNO3 of pH 11 carrier stream (1.2 ml/min) and measuring the I with an ISE. The detection limits, linear ranges, precision, recoveries and analysis times of the four methods were compared (details given). The online FIA method was the simplest and most rapid method with a detection limit of 60 µg/l of I.
Cyanide Electrode Polarography Spectrophotometry Method comparison Indirect

"Determination Of Total Phosphorus In Waters And Waste Waters By Online Microwave-induced Digestion And Flow Injection Analysis"
Anal. Chim. Acta 1994 Volume 291, Issue 3 Pages 233-242
Richard L. Benson*, Ian D. McKelvie and Barry T. Hart, Ian C. Hamilton

Abstract: Digestion was performed using a flow-through reactor in a modified domestic microwave oven and the orthophosphate formed was detected as phosphomolybdenum blue after online filtration. Different digestion mixtures were evaluated and a 10 g/l acidified solution of potassium peroxydisulfate was selected. Phosphorus standards or unfiltered effluent samples were continuously mixed online with the digestion reagent and the solution was passed through the microwave reactor. A 30 µL portion of the solution was injected into a water carrier stream via a PTFE rotary valve, and sequentially merged with a further water carrier stream, the colorimetric reagent and the reducing reagent. The transmittance was monitored by a solid-state photometer incorporating red a light-emitting diodes (635 nm). The technique was rapid (7 samples/h, 4 replicates). The calibration graph was linear upto 18 mg/l of P with a detection limit of 0.09 mg/l.
Phosphorus Sample preparation Microwave Online digestion Filter Light emitting diode

"Analysis Of Total Dissolved Nitrogen In Natural Waters By Online Photooxidation And Flow Injection"
Anal. Chim. Acta 1994 Volume 293, Issue 1-2 Pages 155-162
I. D. McKelvie*, M. Mitri, B. T. Hart, I. C. Hamilton and A. D. Stuart

Abstract: The method is based on the conversion of inorganic and organic nitrogen species to nitrate by photooxidation by UV radiation in an alkaline peroxodisulfate median. After reduction, excess peroxodisulfate reagent was removed with sodium metabisulfite and the solution was injected into a flow injection manifold to determine nitrate by reduction to nitrite, diazotization, coupling and detection at 540 nm. A sample stream (0.3 ml/min) and a 10 g/l potassium peroxodisulfate/8.5 g/l sodium tetraborate stream (0.3 ml/min) were merged and passed through the UV photoreactor coil (3 m x 0.3 mm i.d.). The stream was passed through a Accurel debubbler and merged with a 10 g/l sodium metabisulfite stream (0.3 ml/min). The solution was injected into the 2.8 M NH4Cl pH 8-8.5 carrier stream (0.5 ml/min) of the FIA system. After passing through the Cd reduction column (12 cm x 2 mm i.d.), the stream was merged successively with streams of 1% sulfanilamide and 0.1% N-1-naphthylethylenediamine dihydrochloride (both at 0.5 ml/min). The absorbance was measured at 540 nm. The calibration graph was linear from 0.03-3 mg/l of N; the RSD (n = 8) for 1 mg/l of N was 0.47%. The method was applied to natural and waste water samples.
Nitrogen, total Spectrophotometry Debubbler Reduction column

"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

"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

"Flow-through Tubular Ion-selective Electrodes Responsive To Anionic Surfactants For Flow Injection Analysis"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 115-121
J. Alonso, J. Bar&oacute;, J. Bartrol&iacute;, J. S&agrave;nchez and M. Del Valle*

Abstract: A flow injection system with potentiometric detection was described for monitoring anionic surfactant concentrations in printing plate wash solutions. Sample (20 µL) was injected into a 0.2 M K2SO4 stream (0.87 ml/min, pH 2.5) which was merged with a 5 µM-sodium dodecylbenzenesulfonate stream (1.34 ml/min). The merged flow passed through a tubular, flow-through detector cell. The inner wall of the detector cell was coated with a sensing membrane consisting of 25% high mol. wt. PVC, 62.5% o-nitrophenyloctyl ether and 12.5% of a quaternary ammonium salt of dodecylbenzenesulfonate. The potentials were measured against a double junction Ag/AgCl electrode with a 1 M K2SO4 salt bridge. Surfactant concentrations ranging from 0.1-0.5 mM were measured in the presence of up to 0.3 M NaOH with overall mean errors of 4.1%. The sampling frequency was 30 samples/h.
Dodecylbenzenesulfonate Surfactants, anionic Electrode Electrode Electrode Electrode Potentiometry Interferences

"Online Pervaporation Separation Process For The Potentiometric Determination Of Fluoride In 'dirty' Samples"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 246-252
I. Papaefstathiou, M. T. Tena and M. D. Luque de Castro*

Abstract: The FIA method was based on the reaction of fluoride with hexamethyldisilazane (HMDSA) in acidic medium to form trimethylfluorisilane (TMFS). TMFS was evaporated, diffused through a hydrophobic membrane and adsorbed into a NaOH acceptor stream. Fluoride was detected using a fluoride ISE. Streams of the sample solution and 1.5% HMDSA in 2 M H2SO4 were merged to give a combined flow of 0.5 ml/min and passed through a reactor coil (300 cm length) at 90°C. A portion of the solution was injected into a 1 M H2SO4 carrier stream (1.3 ml/min) and transferred to the pervaporation cell which was maintained at 80°C. The volatile TMFS was collected in a 0.05 M NaOH acceptor stream (1.3 ml/min). The acceptor stream was merged with a stream (1.3 ml/min) containing 0.2 M acetic acid and 1 M KCl before passing to the ISE detector. The system was operated in the continuous- and stopped-flow modes. The linear dynamic ranges were 40-100 ng/l (RSD = 2.6%) in the continuous-flow mode and 5-20 mg/l (RSD = 3.58%) in the stopped-flow mode. The sampling frequencies were 8 samples/h for the continuous-flow mode and 6 samples/h for the stopped-flow mode. The method was used to determine fluoride in water, fertilizers and ceramic industry waste water. The recovery of 10 and 50 mg/l fluoride from tap and well water was >89% and the RSD (n = 3) was 3.45%.
Fluoride Potentiometry Electrode Pervaporation Stopped-flow Hydrophobic membrane

"Evaluation Of Flow Injection Methods For Ammonium Determination In Waste Water Samples"
Anal. Chim. Acta 1995 Volume 311, Issue 2 Pages 165-173
A. Cerd&agrave;, M. T. Oms, R. Forteza and V. Cerd&agrave;*

Abstract: Five flow injection methods, namely (i) the Berthelot reaction adapted to FIA, (ii) the Berthelot reaction in combination with gas diffusion separation, (iii) the salicylate modification of the Berthelot reaction, (iv) an acid-base spectrophotometric method with gas diffusion separation and (v) gas diffusion separation with conductivity detection, were compared for the determination of ammonia in waste water. The linear range, detection limit and reproducibility of each method were measured. All methods produced a detection limit (0.03-1 mg/l) which was satisfactory for the determination of ammonia in waste water. Interferences were eliminated by using gas diffusion separation. Gas diffusion methods coupled with spectrophotometric or conductometric detection were found to have good precision and sensitivity and were reliable alternatives to the Berthelot methods. The conductivity method had the added advantage of requiring only one reagent (NaOH). Methods based on the Berthelot reaction required a reaction temperature of 60°C which made them unsuitable for in situ applications. All five method were applied to the analysis of waste water samples containing 5-60 mg/l ammonia and the results were compared.
Ammonium Conductometry Spectrophotometry Gas diffusion Heated reaction Manifold comparison Membrane Method comparison Interferences

"Differential Flow Injection Potentiometry"
Anal. Chim. Acta 1995 Volume 311, Issue 2 Pages 175-181
Ivelin Rizov* and Liliana Ilcheva

Abstract: Flow injection potentiometric methods using two different ISE placed in series are described for the simultaneous determination of (i) nitrate and chloride and (ii) nitrate and ammonium. The flow injection manifold for the determination of nitrate and chloride consisted of a nitrate ISE separated from a chloride ISE by a reaction coil of 254 cm x 0.51 mm i.d. A sample volume of 60 µL was injected into a 0.04 M Na2SO4 carrier stream (6.3 ml/min). The nitrate concentration was determined using the chloride ISE as a reference electrode and vice versa. The RSD (n = 13) for the determination of 0.1 mM nitrate and 1 mM chloride were 1.1 and 0.9%, respectively. A similar manifold is described for the determination of nitrate and ammonium using nitrate and ammonium ISE separated by a reaction coil of 284 cm x 0.51 mm i.d. The RSD (n = 12) for the determination of nitrate and ammonium in waste water from a urea production plant were 1.1 and 0.9%, respectively.
Ammonium Chloride Nitrate Electrode Electrode Electrode Potentiometry Dual detection

"Sequential Injection Analysis Of Nitrites And Nitrates"
Anal. Chim. Acta 1995 Volume 315, Issue 3 Pages 321-330
M. T. Oms, A. Cerd&agrave; and V. Cerd&agrave;*

Abstract: A sequential injection system for the analysis of nitrate and nitrite is described. The sample and reagents are aspirated and mixed by flow reversal while being propelled to a reaction coil or to the detector. The determination of nitrite is based on the Griess-llosvay reaction. Nitrate is previously reduced by hydrazine in alkaline medium and analyzed as nitrite. The sequencing and overlap of the stacked zones are key parameters that have been studied together with concentrations of reagents, influence of temperature and potential interfering ions. Under the final optimal conditions up to 400 µM Of nitrite and nitrate can be analyzed, the detection limits being 0.07 ppm and 0.2 ppm respectively. The method has been tested with prepared standard samples, atmospheric aerosol filter extracts and wastewater samples. (14 references)
Nitrate Nitrite Sequential injection Interferences Flow reversal

"Gas Diffusion Techniques Coupled Sequential Injection Analysis For Selective Determination Of Ammonium"
Anal. Chim. Acta 1996 Volume 318, Issue 3 Pages 251-260
M. T. Oms, A. Cerd&agrave;, A. Cladera, V. Cerd&agrave;* and R. Forteza

Abstract: A computer-controlled sequential injection analysis system for the determination of ammonium ions in water is described. A 75 µL sample and 100 µL 0.01 M NaOH were sequentially aspirated and mixed by flow reversal while being propelled (2 ml/min) to a gas diffusion unit. Ammonia diffused through a Durapore hydrophobic membrane (0.22-0.45 µm pore size, 125 µm thick) and was collected in 1 mL 80 µM-bromothymol blue (BTB) at pH 6. The BTB was propelled to a spectrophotometer and the absorbance was measured at 620 nm. The calibration graph for ammonium ions was linear for up to 60 mg/l and the RSD (n = 10) at 30 mg/l was 2.5%. The detection limits were 2 and 0.5 mg/l for one and five flow reversals, respectively. No interference from a 20-fold excess of Cu(II), Fe(III) and Zn, a 40-fold excess of carbonate or sulfite, Ca and Mg or a 100-fold excess of chloride, nitrate or sulfate was observed. The method was applied to the analysis of filtered waste water and aqueous extracts of atmospheric aerosols. The results were confirmed by a FIA method based on the formation of indophenol blue.
Ammonium Spectrophotometry Sequential injection Interferences Gas diffusion Hydrophobic membrane

"Online Multicomponent Determination Of Organic Compounds In Water Following Gel-permeation Chromatographic Separation"
Anal. Chim. Acta 1996 Volume 319, Issue 1-2 Pages 165-175
Jolanta Oleksy-Frenzel* and Martin Jekel

Abstract: A system coupling GPC with air-segmented flow analyzer.s for dissolved organic carbon (DOC), nitrogen (DON) and halogens (DOX) was described for the characterization of water samples. The chromatography was carried out on a Fractogel TSK 40 HW column (70 cm x 16 mm i.d.) with a sample injection volume of 1 ml, phosphate buffer at pH 7 as the mobile phase (0.8 ml/min) and UV-visible diode array detection (190-800 nm). The column effluent was divided into two streams. One steam passed to the DOC analyzer. and the other to the DON analyzer. and then to the DOX analyzer.. The DOC analyzer. was based on the H2SO4 oxidation of organic carbons to CO2 which was collected via a gas diffusion unit and detected photometrically with a pH indicator. The DON analyzer. was based on the oxidation of organic nitrogen to nitrate by UV digestion in the presence of peroxodisulfate for spectrophotometric detection. The DOX analyzer. was based on the potentiometric detection of halides at a Ag/AgCl electrode. The system was tested with various organic compounds and quantitative recoveries were obtained. The system was applied to the characterization of filtered waste water from chemical processing.
Organic compounds GPC Potentiometry Spectrophotometry Sample preparation Gas diffusion UV reactor Photochemistry

"Determination Of Total Phenols In Waters And Waste Waters Using Flow Injection With Electrochemical Detection; An Alternative To The Standard Colorimetric Procedure"
Anal. Chim. Acta 1996 Volume 323, Issue 1-3 Pages 39-46
M. J. Christophersen and T. J. Cardwell*

Abstract: The flow injection manifold for the determination of total phenols was equipped with an up-stream coulometric carbon electrode at +0.35 V (reference electrode not given) for the oxidative removal of interference followed by an amperometric carbon electrode at +0.78 V for the oxidative detection of phenols. Phosphate buffer of pH 6.8 was used as carrier (0.5 ml/min) and the injection volume was 10 µL. The method was calibrated with 2,5-dichlorophenol, and a linear calibration graph was obtained for 0.1-20 mg/l. RSD were 0.5-4% within the calibration range. The method was tested with several synthetic aqueous samples and found to give more accurate results for samples containing p-substituted phenols and nitrophenols than the 4-aminoantipyrine spectrophotometric method. The proposed method was applied to the analysis of industrial waste water samples.
Phenols, total Amperometry Electrode Interferences

"Determination Of Total Phosphorus In Waters And Waste Waters By Online UV/thermal Induced Digestion And Flow Injection Analysis"
Anal. Chim. Acta 1996 Volume 326, Issue 1-3 Pages 29-39
Richard L. Benson*, Ian D. McKelvie, Barry T. Hart, Yen B. Truong and Ian C. Hamilton

Abstract: The online FIA method utilized a two-stage UV photo-oxidation/thermal digestion procedure and oxidizing/hydrolyzing reactions to convert phosphorus compounds to orthophosphate for detection by the phosphomolybdenum blue reaction. A sample stream (0.69 ml/min) was merged with 6 g/l ammonium peroxydisulfate in 2.1 M perchloric acid (0.69 ml/min) and passed through a UV digestor (8 W) and a thermal digestor at 90°C. A 60 µL portion of the digestate was injected into a water carrier stream (1.24 ml/min) and sequentially merged with a water diluent (0.58 ml/min), 10 g/l ammonium molybdate in 35 ml/l H2SO4 (0.86 ml/min) and 0.2 g/l tin(II) chloride/2 g/l hydrazinium sulfate in 28 ml/l H2SO4 (0.58 ml/min). The transmittance of the mixture was monitored with a solid-state photometer equipped with a red light-emitting diode (635 nm) and an optical path of 0.8 mm. The method was validated with a series of organic and condensed phosphorus species at concentrations of 10 mg/l; recoveries of >85% were obtained. The calibration graph was linear for 0.5-18 mg P/l and the detection limit was 0.15 mg/l. The sample throughput was 8 samples/h. The method was applied to waste water and the results were confirmed by a conventional batch digestion method.
Phosphorus Spectrophotometry Sample preparation Light emitting diode UV reactor Photochemistry

"Determination Of Ammonia In Water And Industrial Effluent Streams With The Indophenol Blue Method Using Sequential Injection Analysis"
Anal. Chim. Acta 1997 Volume 344, Issue 3 Pages 281-289
J. F. van Staden* and R. E. Taljaard

Abstract: Water and industrial effluents were analyzed by the sequential aspiration of zones of 1 M NaOH carrier solution, sample, 50 mg/l phenol reagent and hypochlorite reagent into a holding coil, followed by three flow reversals during which the zones passed through reaction coils and finally into a detector for detection at 640 nm. The phenol reagent consisted of 3 g pink phenol, 12 g NaOH and 40 mL ethanol diluted to 100 mL with H2O; the hypochlorite reagent comprised 3 g NaOH, 2 g sodium tetraborate decahydrate and 60 mL bleach (3.5% hypochlorite) diluted to 100 mL. A schematic diagram is given of the sequential injection analysis system. The calibration graph was linear up to 50 mg/l NH3, recoveries were 98-106% and the sampling rate was 16/h. The RSD were 3. The effects of interferents were not significant.
Ammonia Spectrophotometry Sequential injection Interferences Flow reversal

"A Novel Gas Diffusion/flow Injection System Coupled With A Bulk Acoustic-wave Impedance Sensor For Total Inorganic Carbonate And Its Application To Determination Of Total Inorganic And Total Organic-carbon In Waters"
Anal. Chim. Acta 1997 Volume 349, Issue 1-3 Pages 143-151
Xiao-li Su, Li-hua Nie and Shou-zhuo Yao*

Abstract: A novel flow injection analysis (FIA) system has been developed for the rapid and selective determination of total inorganic carbonate (TIC). The method is based on the diffusion of CO2 across a PTFE gas-permeable membrane from a stream of 0.5 mol L-1 H2SO4 (0.50 mL min-1) and water (0.50 mL min-1) merging into a stream of 10 mM tris(hydroxymethylamino)-methane containing 0.5 mM KCl (1.00 min min-1). The CO2 trapped in the acceptor solution is determined online by a bulk acoustic wave impedance sensor and the signal is proportional to the concentration of TIC present in the original samples. The proposed system was applied to the direct determination of TIC in natural and waste waters and the indirect determination of the total organic carbon content based on wet chemical oxidation of the samples, it exhibited a linear frequency response up to 20 mM bicarbonate with a detection limit of 10 µM, and the precision was better than 1% (RSD) at a throughput of 45 samples per hour. The effects of composition of acceptor stream, cell constant of the conductivity sensor, sample volume, flow rates and potential interferents on the FIA signals were discussed in detail. 32 References
Carbon, organic, total Carbon, inorganic, total Sensor Gas diffusion Teflon membrane Interferences Optimization

"Evaluation Of Spectrophotometric Methods For Determination Of Orthophosphates By Sequential Injection Analysis"
Anal. Chim. Acta 1997 Volume 350, Issue 1-2 Pages 21-29
A. Mu&ntilde;oz, F. Mas Torres, J. M. Estela and V. Cerda*

Abstract: Three methods for the determination of orthophosphate have been studied by using the same sequential injection analysis manifold, namely the vanadomolybdate, the malachite green and the molybdenum blue methods. The calibration graphs were linear up to 18.0, 0.4 and 4.0 mg P l-1, respectively. Relative standard deviations and detection limits were 2.1%, 18% and 1.7% and 0.15, 0.01 and 0.01 mg P L-1 respectively. The three methods were applied to the determination of phosphate in several water samples, both from natural and waste origin at a frequency of about 30 determinations per hour.
Phosphate Spectrophotometry Sequential injection Method comparison

"Total Nitrogen Determination By Flow Injection Using Online Microwave-assisted Digestion"
Anal. Chim. Acta 1997 Volume 351, Issue 1-3 Pages 273-279
A. Cerd&agrave;, M. T. Oms, R. Forteza and V. Cerd&agrave;*

Abstract: A method for the determination of total nitrogen in wastewaters involving flow injection and on-line microwave-assisted digestion is described. The method is based on the oxidation of nitrogen-containing compounds to nitrate by means of peroxodisulphate using a microwave oven as a radiation source. Nitrate is determined by the Griess-Ilosvay reaction, after reduction to nitrite by hydrazine under alkaline conditions, using sulfaniliamide and N-(1-naphtyl)ethylene diamine. A thorough study of the factors affecting the digestion process has been carried out using several nitrogen-containing compounds as test substances. Under the optimized conditions, the described method allows quantitative digestion of all the model compounds for concentrations up to 20 mg L-1 N. The method enables the analysis of 10 samples in triplicate per hour, the relative standard deviation of 10 replicates being ~3%. The detection limit is 0.21 mg l- N. The system has been applied to the determination of total nitrogen in wastewaters and the results have been compared with those obtained by Kjeldahl digestion.
Nitrogen, total Sample preparation Microwave Online digestion Method comparison Optimization

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

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

"A Novel FIA Configuration For The Simultaneous Determination Of Nitrate And Nitrite And Its Use For Monitoring An Urban Waste Water Treatment Plant Based On N/D Criteria"
Anal. Chim. Acta 1998 Volume 359, Issue 1-2 Pages 173-183
D. Gabriel, J. Baeza, F. Valero and J. Lafuente*

Abstract: A novel FIA configuration for the simultaneous determination of nitrate and nitrite, and its automation for monitoring an urban wastewater treatment plant (WWTP) based on nitrification/denitrification criteria, are proposed. The detection range achieved is 0.25-50 mg L-1 for nitrate and 0.05-5 mg L-1 for nitrite (0.056-11.29 mg N-NO-3 L-1 and 0.015-1.52 mg N-NO-2 L-1). The max. sampling frequency is 180 samples/day and the Relative Standard Deviation (RSD, n=5) was 1.1% at 5 mg L-1 nitrite and 2.3% at 50 mg L-1 nitrate plus 1 mg L-1 nitrite. The particle size of the reductant (Cd) and the use of Cu as a catalyst influencing the stability of the reduction column were examined and an electronic calibration system was developed in order to increase the capacity of the equipment to operate unattended with a view to its use at WWTP. The max. unattended deployment time is four days. The proposed configuration was validated by analyzing real water samples at a pilot plant based on nitrification/denitrification criteria with optimal results.
Nitrate Nitrite Spectrophotometry Process monitoring Remote instrument Optimization Reduction column

"Introduction Of Hydrogen Peroxide As An Oxidant In Flow Injection Analysis: Speciation Of Chromium(III) And Chromium(VI)"
Anal. Chim. Acta 1998 Volume 361, Issue 1-2 Pages 125-131
Jens E. T. Andersen*

Abstract: Hydrogen peroxode was used as an oxidant in flow injection analysis (FIA). The formation of gaseous components during the analysis was suppressed by maintaining the concentration of H2O2 <0.15% in 0.1 M NaOH. By this method, Cr(III) was oxidized online to Cr(VI) which was detected spectrophotometrically at 548 nm by complexation with 1,5-diphenylcarbazide (DPC). Linear responses were found for concentrations. <20 mg/l and the sensitivities obtained of the pure species were 0.0225±0.0015 L/mg for Cr(III) and 0.0420±0.0015 L/mg for Cr(VI). For the speciation of Cr(III) and Cr(VI), the anal. of both species was performed by treating them as mutual interferences. Thus, the total amt. of Cr species was measured by FIA and the total amount of Cr was measured by Graphite Furnace Atomic Absorption Spectrometry (GFAAS). The speciation was performed at concentrations. >6 mg/L which is suitable for online monitoring of e.g. waste waters.
Chromium(III) Chromium(VI) Spectrophotometry Sample preparation Speciation Method comparison Process monitoring Interferences

"Potentiometric Flow Injection Determination Of Cadmium In Waste Waters Including Inline Ion-exchange Separation/concentration"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 155-161
Cristina M. C. M. Coutoa, Jos&eacute; L. F. C. Limaa, M. Concei&ccedil;&atilde;o B. S. M. Montenegroa, Boaventura F. Reisb and Elias A. G. Zagattob,*

Abstract: A flow injection system including an ion exchange resin mini-column was proposed for potentiometric determination of Cd in wastewater. Cd was preferential and quantitatively retained as chloro-complex by a strongly basic anion exchange resin (AG 1-X8, 200-400 mesh, chloride form) mini-column (2.0 cm height, 1.85 mm inside diameter), whereas other sample metallic cations and inert components were wasted. Retained complexes were further eluted towards detection. The flow-through detector was a Cd homogeneous crystalline double membrane tubular electrode of increased sensitivity; summation of the potentials related to each membrane was performed using an external electronic device. This system was used to determine Cd in residual wastewater; Cd concentrations were 0.056-56.2 mg/L. Precise results (relative standard deviation ~7%) in agreement with those obtained by flame atomic absorption spectrometry were obtained at a rate of 15-20 determinations/h.
Cadmium Potentiometry Ion exchange Electrode Electrode Complexation Resin Preconcentration Method comparison

"Flow Injection Biamperometric Determination Of Nitrate (by Photoreduction) And Nitrite With The NO2-/I- Reaction"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 241-249
I. Gil Torr&oacute;a, J. V. Garc&iacute;a Mateob and J. Mart&iacute;nez Calatayuda,*

Abstract: An unsegmented continuous-flow method for the determination of nitrite and nitrate is proposed. Nitrate is photoreduced by UV irradn. with a low-pressure 8 w Hg lamp. The nitrite in the sample and that resulting from the photoredn. of nitrate were used to oxidize iodide ion. Tri-iodide thus formed is detected biamperometrically in excess iodide by using a flow-cell furnished with two Pt electrodes polarized at 100 mV. The limits of detection, throughput and reproducibility (n = 26) thus achieved for nitrite and nitrate are 25 and 50 µg L-1, 27 and 25 h-1, and 1.2 and 1.6%, respectively. The proposed method was used to determine nitrate and nitrite in natural waters, waste waters, soils, meat products and fertilizers. (29 References)
Nitrate Nitrite Biamperometry Electrode Catalysis Reduction column Indirect Photochemistry UV reactor

"Determination Of Ammonia In Wastewaters Containing High Concentrations Of Surfactants By Flow Injection Potentiometry With Online Sample Clean-up"
Anal. Chim. Acta 1998 Volume 367, Issue 1-3 Pages 193-199
Hongda Shen, Terence J. Cardwell* and Robert W. Cattrall

Abstract: It was demonstrated that surfactants lead to problems in the anal. of NH3 in gas-diffusion flow injection by wetting the membrane to allow transport of potentially interfering species to the detector. An online clean-up procedure, using an activated C cartridge to remove ionic and non-ionic surfactants (≤1000 mg/L) and other organic compounds from aqueous samples, is described. Ammoniacal nitrogen was determined in synthetic samples by gas-diffusion flow injection with a nonactin-based potentiometric sensor used as an NH4+ ion detector. Analyses were performed at a sampling rate of ~25/h; the cartridge was effective for at least 1000 injections of 50 µL samples at 1-180 mg/L concentrations The procedure was used to analyze wastewater; it was efficient in removing ionic and non-ionic surfactants from acidified (pH 1) samples.
Ammonia Potentiometry Electrode Activated carbon Gas diffusion Interferences Column

"Procedures For The Storage And Digestion Of Natural Waters For The Determination Of Filterable Reactive Phosphorus, Total Filterable Phosphorus And Total Phosphorus"
Anal. Chim. Acta 1998 Volume 375, Issue 1-2 Pages 5-47
W. Maher* and L. Woo

Abstract: A review, with 150 references, is given. An overview of the forms of P species likely to be encountered in natural waters and the implications for the measurement of filterable and total P is given. Procedures reported in the literature for the storage and digestion of water samples for filterable reactive P (FRP), total filterable P (TFP) and total P (TP) measurements are summarized and the advantages and limitations of methods discussed. Water samples for FRP and TFP measurements need to be filtered immediately on collection as exchange on and off particles may occur in the sample container. Slow freezing of filtered or turbid water samples in acid washed low density polyethylene bottles appears to be satisfactory for the long term storage (years) of a variety of water sample types. Storage of water samples at room temperature or refrigeration (1-5°C) with a preservative is suitable only for short term storage (days-months). If water samples contain <20 µg P/L, adsorption to containers may be significant. Batch digestion of samples with alkaline or acid peroxodisulfate using autoclave or microwave heating offers the advantages of ease, simplicity and precision. Good recoveries of P from a range of P compounds containing P-O-P, C-O-P and C-P bonds expected in natural waters have been reported. If turbid samples are to be analyzed, caution must be exercised to ensure that the C or suspended solids concentration. does not exceed the capacity of the digestion procedure to oxidize the C present and release occluded P from particulate materials. Better recoveries of P from turbid water samples are achieved using microwave heating with closed vessels, probably because of the higher temps. and pressures generated. The use of online heating (microwave, thermal induced) coupled with flow injection analysis and using peroxodisulfate or an oxidizing acid mixture should also allow the automation of TFP and TP measurements. Reliable procedures for the removal of unwanted particulate material prior to or after the digestion step need to be developed.
Phosphorus Sample preparation Review

"Determination Of Glycerol In Water By Flow Injection Analysis - A Novel Way Of Measuring Viscosity"
Talanta 1976 Volume 23, Issue 5 Pages 409-410
D. BetteridgeJ. Rika

Abstract: Flow injection analysis of mixtures of glycerol and water suggested that precise results may be obtained for the composition of miscible liquid mixtures over a narrow range. Since the viscosity is an important factor in the extent of mixing it could be determined simply and rapidly by this technique.
Glycerol Spectrophotometry Viscosity

"Spectrophotometric Determination Of Cyanide By Unsegmented Flow Methods"
Talanta 1984 Volume 31, Issue 9 Pages 673-678
A. Rios, M. D. Luque de Castro and M. Valcarcel

Abstract: The reaction of CN- with chloramine T, pyridine and barbituric acid to form a dye has been used as the basis for three unsegmented-flow techniques, with spectrophotometric detection at 578 nm. In the normal flow injection technique (for scarce or valuable samples), the sample was injected into the carrier stream, which consisted of a mixture of chloramine T solution and buffer solution In the reversed flow injection technique (for waste waters), the main carrier stream was the sample solution, which was mixed with the secondary, reagent carrier stream. In the continuous-flow technique, reversed flow was used, without an injection valve, thereby allowing continuous-flow of reagent and analyte streams. Diagrams of the three manifolds are presented, together with optimum flow rates, reactor lengths and injection volume Normal flow injection analysis afforded the best sensitivity (rectilinear range 0.1 to 1.0 µg mL-1 of CN-), but the reversed system permitted determination over a wider range (0.3 to 5.0 µg mL-1); the rectilinear range for the continuous-flow technique was 0.7 to 4.0 µg mL-1. Interfering species, which were essentially the same for all three techniques, are listed.
Cyanide Spectrophotometry Interferences Process control Manifold comparison Reverse

"Fluorimetric Determination Of Uranium(VI) In Waters By Flow Injection Analysis After Preconcentration On A Silica Gel Micro-column"
Talanta 1992 Volume 39, Issue 7 Pages 795-799
Josef Havel, Milan Vrchlabsk&yacute; and Zdenk Kohn

Abstract: Uranyl cations were selectively adsorbed or pre-concentrated on a PTFE or fused-silica column (4 cm x 2 mm) of activated silica gel (Merck Kieselgel or Kavalier Silpearl; 0.05 to 0.2 mm diameter) from a medium (1.5 mL min-1) containing 0.03 M EDTA, 0.05 M NaF and 0.06 M tartrate (pH 9.3). The column was washed with water or NaClO4 before elution of uranyl with aqueous 1.33 M H3PO4 - 1.33 M H2SO4 and fluorimetry at 495 nm (excitation at 325 nm). The estimated detection limit was 0.1 to 0.2 µg of U. For 18 tested cations tolerable concentration. (interference 2% of signal) ranged from 20-fold for Zr(IV) to 2300-fold for La. The method was verified with synthetic aqueous solution and applied to waste and natural waters, for which the reproducibility ranged from 2.7 to 5.0%. A method for the selective determination of trace U(VI) uses flow injection analysis (FIA) with fluorimetric detection. U(VI) is selectively separated and(or) pre-concentrated from a volume of 20 mL on an activated silica gel microcolumn (2 x 40 mm) from a medium of 0.03 M EDTA, 0.06 M tartrate, and(or) 0.05 M NaF at pH 9.3. After washing of the column, the U is eluted with a mixture of 1.33 M H2SO4 and H3PO4 and determined with a relative standard deviation not exceeding 6% for concentrations. in the range 10^-250 µg/L. The detection limit was estimated to be 0.1-0.2 mg U. The method was verified using water samples with a high content of interfering elements and applied to the analysis of wastewater and natural waters.
Uranium(VI) Fluorescence Interferences Preconcentration Silica gel

"Preconcentration Of Iron(III), Cobalt(II) And Copper(II) Nitroso-R Complexes On Tetradecyldimethylbenzylammonium Iodide-naphthalene Adsorbent"
Talanta 1995 Volume 42, Issue 3 Pages 337-344
Bal K. Puri and Sanjay Balani

Abstract: Iron, cobalt and copper form colored water soluble anionic complexes with disodium 1-nitroso-2-naphthol-3-6-disulphonate (nitroso R-salt). The anionic complex is retained quantitatively as a water insoluble neutral ion associated complex (M-nitroso R-TDBA) on tetradecyldimethylbenzylammonium iodide on naphthalene (TDBA+I--naphthalene) packed column in the pH range of: Fe(III): 3.1-6.5, Co: 3.4-8.5 and Cu 5.9-8.0 when their solutions are passed individually over this adsorbent at a flow rate of 0.5-5.0 ml/min. The solid mass consisting of an ion associated metal complex along with naphthalene is dissolved out of the column with 5 mL dimethylformamide/chloroform and metals are determined spectrophotometrically. The absorbance is measured at 710 nm for iron, 425 nm for cobalt and 480 nm for copper. Beers law is obeyed in the concentration range 9.2-82 µg of iron, 425 nm for cobalt cobalt and 3.0-62 µg of copper in 5 mL of final DMF/CHCl3 solution. The molar absorptivities are calculated to be Fe: 7.58 x 10^3, Co: 1.33 x 10^4 and Cu: 4.92 x 10^4 M 1 cm-1. Ten replicate determinations containing 25 µg of iron, 9.96 µg of cobalt and 3.17 µg of copper gave mean absorbances 0.677, 0.450 and 0.490 with relative standard deviations of 0.88, 0.98 and 0.92%, respectively. The interference of large number of metals and anions on the estimations of these metals has been studied. The optimized conditions so developed have been employed for the trace determination of these metals in standard alloys, waste water and fly ash samples.
Cobalt(II) Copper(II) Iron(III) Spectrophotometry Preconcentration

"Flow Injection Analysis Spectrophotometric Determination Of Nitrite And Nitrate In Water Samples By Reaction With Proflavin"
Talanta 1996 Volume 43, Issue 2 Pages 239-246
R. Segarra Guerreroa, C. Gom&eacute;za and J. Mart&iacute;nez Calatayudb,*

Abstract: A flow injection manifold is proposed for determination of nitrite based on the reaction with 3,6-diamino acridine (proflavin sulfate) in hydrochloride acid medium. The assembly is adapted for nitrate determination by including a reductive column filled with copperized cadmium. The influence of foreign substances is also studied. The method gives a linear calibration graph over the range 0.06-4 mg L-1 nitrite, with an RSD <0.5%. The method was applied to nitrite and nitrate determinations in either waste water or coastal marine water samples. For the determination of nitrites a water sample was merged in a mixing chamber with a reagent stream of 0.2 mM proflavin/L M HCl and the resulting solution was injected into a carrier stream (1.79 ml/min) of water. The absorbance was then measured at 328 nm. For the determination of nitrates a copperized Cd column (10 cm x 5 mm i.d.; particle size 4 mm) was inserted into the system before the mixing chamber to reduce nitrate to nitrite. Calibration graphs were linear for 0.06-4 mg/l of nitrite with a RSD (n not given) of >0.5%. The effects of foreign compounds on nitrite determination are tabulated.
Nitrate Nitrite Spectrophotometry Interferences Reduction column

"Photometric Determination Of Anionic Surfactants With A Flow Injection Analyser That Includes A Chromatomembrane Cell For Sample Preconcentration By Liquid-liquid Solvent Extraction"
Talanta 1996 Volume 43, Issue 6 Pages 819-824
L. N. Moskvina, J. Simonb,*, P. L&ouml;fflerb, N. V. Michailovaa and D. N. Nicolaevnaa

Abstract: Reagent streams of 0.125 mM methylene blue and 0.1 M sodium acetate buffer were merged and passed through a mixing coil (30 cm x 5 mm i.d.). A sample stream was then merged with the reagents and mixing was performed in a similar coil; all flow rates were 0.45 ml/min. The resulting solution passed to a chromatomembrane cell via an eight-channel 16-part multifunctional valve. The cell (cf. Moskvin and Simon, Ibid., 1994, 41, 1765) was surrounded by CHCl3. The aqueous phase flow allowed pre-concentration of the preformed ion-pair complex to occur at the phase boundary. The aqueous phase flow was stopped and the organic phase flow was started which extracted the ion-pair complex and passed to the spectrophotometer for detection at 650 nm. Anionic surfactants were determined in the range 0.02-5 mg/l in waste water. The pre-concentration mechanism is discussed.
Surfactants, anionic Spectrophotometry Sample preparation Preconcentration Chromatomembrane Solvent extraction

"High-sensitivity Flow-based Analysis System Using A Semiconductor Laser And Thin Long Flow-through Cell For The Determination Of Total Phosphorus In Water"
Talanta 1996 Volume 43, Issue 9 Pages 1471-1479
Takashi Korenagaa,* and Fusheng Suna

Abstract: A flow-through cell with an optical pathlength of 10 cm machined from a 2.5 cm diameter PTFE rod (details given) was used in conjunction with a GaAlAs semiconductor laser source (emission wavelength 793 nm) and a Hamamatsu model S1087-01 photodiode detector. A light-emitting diode (Toshiba model TLS143) and a second photodiode were used to generate a reference signal. In the flow injection determination of P in water, a 300 µL portion of sample was injected into a stream of 0.3% K2S2O8 solution (600 µL/min) and the resulting mixture was passed through a reaction coil (10 m x 1 mm i.d.) at 140°C and then mixed with color reagent prepared by mixing 7.2% ascorbic acid solution with with 0.048% antimony potassium tartrate hemihydrate/1.2% ammonium molybdate tetrahydrate solution in 8% H2SO4 in the ratio 1:5. The mixture was passed through a second reaction coil (10 m x 1 mm i.d.) at 140°C and then into the detector cell. The calibration graph was linear for 1-50 µg/l of P, and for 20 µg/l of P the RSD was 1% (n = 10). The limit of detection was 0.6 µg/l and recoveries of various P compounds were 94-107%. The method was applied to eight samples of waste water, 18 samples of treated water and five samples of natural water; the results agreed with those obtained by an official method.
Phosphorus Spectrophotometry Light emitting diode Photodiode

"Amberlite XAD Resin Solid-phase Extraction Coupled Online To A Flow Injection Approach For The Rapid Enrichment And Determination Of Phenols In Waters And Waste Waters"
Talanta 1997 Volume 44, Issue 8 Pages 1423-1433
Wen-lu Song, Zheng-liang Zhi* and Lian-sheng Wang

Abstract: Filtered water was adjusted to pH 2 with 12 M HCl and a portion (4.4 ml) was injected in to a carrier stream (1.8 ml/min) of HCl of pH 2 and applied to a column (3 cm x 3 mm i.d.) of Amberlite XAD-4 resin (80-120 mesh). The phenols were eluted from the column with 0.1 M NaOH of pH 13 by activating a switching value. The eluate was mixed with a stream (0.22 ml/min) of 0.1% 4-aminoantipyrine in NH4Cl/NaOH buffer of pH 8.5 in a mixing coil (30 cm x 0.8 mm i.d.) and then with a stream (0.22 ml/min) of 0.2% potassium ferricyanide in water adjusted to pH 11 with NaOH in a reaction coil (60 cm x 0.8 mm i.d.). The absorbance was measured at 510 nm. The manifold incorporated two pre-concentration columns operated alternatively; sample throughput was 12 per h. The calibration graph was linear for 0.01-1 µg/ml phenol and the detection limit was 4 ng/ml. The RSD at 0.2 µg/ml was 2.4%. (n = 11). Results agreed with those obtained by a FIA and a manual method. A novel and expeditious approach for direct determination of phenols in water and waste waters based on solid-phase extraction coupled online to a flow injection analysis (FIA) manifold is described. The method employs online pre-concentration of the phenols in an acidified sample (pH = 2.0) onto a 3 cm x 3 mm column packed with Amberlite XAD-4 resin. The phenols are subsequently eluted from the resin into a flowing system with an alkaline solution (pH = 13) by actuating a switching valve; the eluted analytes were then quantified spectrophotometrically as the products of reaction with 4-aminoantipyrine (4-AAP) and potassium ferricyanide on passing through the flow-cell of a detector. The proposed method has a linear calibration range 0.01-1 µg mL-1 of phenol, with a detection limit of 0.004 µg mL-1 (S/N = 3) and a sample throughput of 12 hr-1, investigated with a 4.4 mi sample volume. The relative standard deviation is 2.4% for 0.2 µg mL-1 of the analyte. The sensitivity offered by the procedure was higher by a factor of 13 than that provided by a conventional flow injection analysis method. The analytical scheme of the proposed system is much simpler than its conventional manual counterpart due to the fact that it combines trace enrichment, sample clean-up, derivation and detection in one analytical set-up. The high speed, ease of use and automation, selectivity, and relative freedom from random contamination by sample handling make this method ideal for the phenols monitoring in water and waste waters. (C) 1997 Elsevier Science B.V. 27 References
Phenols Spectrophotometry Sample preparation Preconcentration Amalgamation Preconcentration Solid phase extraction Method comparison Amberlite Resin

"Spectrophotometric Determination Of Iron With Ferrozine By Flow Injection Analysis"
Talanta 1997 Volume 44, Issue 10 Pages 1793-1801
M. I. Pascual-Reguera*, I. Ortega-Carmona and A. Molina-D&iacute;az

Abstract: Two methods for the determination of iron by normal FIA and reversed FIA were developed using sodium 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine-4',4''-disulfonate (ferrozine). The reagent formed a chelate with Fe(II) in hexamethylenetetramine buffered medium at pH 5.5. In one previous reaction coil Fe(III) was reduced to Fe(II) by ascorbic acid and in the other reaction coil the complexation reaction was developed. The linear range of the determination was 0.5-6 and 0.1-5 µg mL-1 of iron for normal FIA and reversed FIA respectively. The proposed method was sensitive (detection limit 0.012 and 0.010 µg mL-1), rapid and reproducible (RSD 0.3 and 0.28%). The method was satisfactorily applied to the determination of iron in waste water, toadstool tissue, potato leaves, human hair and bauxites at a sampling rate of 90 and 50 samples h-1 for normal FIA and reversed FIA respectively.
Iron Spectrophotometry Reverse Sensitivity

"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 Of Environmental Samples For Nitrate Using An Ion Selective Electrode"
Analyst 1977 Volume 102, Issue 1219 Pages 705-713
E. H. Hansen, Animesh K. Ghose and J. Ruzicka

Abstract: NO3- in soil extracts, wastewater, and fertilizer solutions was determined by addition of a pH 9.5 buffer of 10^-2 M Na tetraborate + 10^-2 M NaOH and measuring the peak max. value in a flow injection system with a NO3--selective electrode. Aqueous extracts of particulate NO3- in air were analyzed without pretreatment. The electrode consisted of tetraoctylammonium bromide in di-Bu phthalate and was calibrated at 10^-5 - 10^-2 M NO3-. For injection of 0.3 mL samples the anal. rate was 90 samples/h. The standard deviation was typically 0.2-0.5 mV, equivalent to 1-2%. The electrode lifetime was 2-3 months. A method is proposed for identifying and correcting for the presence of interferents by observing the shape of each peak and determining its negative elevation. Based on the flow injection principle and employing a nitrate electrode situated in a flow-through cell, a simple, reliable and sensitive method for the automated determination of nitrate and its use for analyzing soil extracts, waste waters, fertiliser solutions and air samples are described. At a sampling rate of 90 samples per hour a standard deviation of only 1-2% is typical. A new approach to identifying and correcting for the presence of interfering species in potentiometric measurements is discussed.
Nitrate Electrode Apparatus Interferences

"Continuous-flow Injection Analysis Of Aqueous Environmental Samples For Chemical Oxygen Demand"
Analyst 1981 Volume 106, Issue 1263 Pages 653-662
Takashi Korenaga and Hisayoshi Ikatsu

Abstract: A method is described for the continuous, rapid determination of chemical oxygen demand (COD). The method is based on flow injection analysis (FIA) and uses acidic potassium permanganate solution as both an oxidant and a spectrophotometric reagent, and glucose as a standard. COD values for aqueous environmental samples, such as industrial wastewaters, are compared with those obtained using the Japanese Industrial Standard (JIS) method and are found to be within an error range of ±30%. The method is comparable to other manual and automatic methods and has several advantages. A sampling rate of 20 samples per hour can be achieved, and the detection limit and precision are 5 mg l-1 as COD and 0.6%, respectively. Chloride ion up to levels of 6000 mg l-1 does not interfere, even in the absence of silver salts.
Chemical oxygen demand Spectrophotometry

"New Approach To The Simultaneous Determination Of Pollutants In Waste Water By Flow Injection Analysis. 1. Anionic Pollutants"
Analyst 1984 Volume 109, Issue 11 Pages 1487-1492
Angel R&iacute;os, M. Dolores Luque de Castro and Miguel Valc&aacute;rcel

Abstract: The general manifold described, which operates on the principle of reversed-flow injection, incorporates several injection valves that permit the insertion of specific reagents for the spectrophotometric determination of each species at different points in the waste-water stream. By positioning a glass - calomel micro-electrode in front of these valves, the pH can be monitored continuously. A single detector is used for analytes undergoing reaction, thereby allowing the concentration. of several pollutants in the sample to be measured at any moment without prior treatment. The scheme is simple, rapid and versatile and has been satisfactorily applied to the concurrent determination of S2- and CN- (and pH) and of NO2- and CN- (and pH). The NO2- determination is the most selective, S2- being the most significant interfering species; NO2- also interferes in the determination of S2-
Cyanide Nitrite pH Sulfide Electrode Potentiometry Spectrophotometry Interferences Process control Reverse

"Sequential Spectrophotometric Determination Of Chromium(III) And Chromium(VI) Using Flow Injection Analysis"
Analyst 1985 Volume 110, Issue 2 Pages 197-199
Jo&atilde;o Carlos de Andrade, Julio Cesar Rocha and Nivaldo Baccan

Abstract: Flow injection analysis was used to speciate Cr(III) and Cr(VI) with 1,5-diphenylcarbazide(I) as reagent. Sexavalent and total Cr (after online oxidation of Cr(III) with Ce(IV)) can be determined sequentially, as Cr(III) does not react with I; Cr(III) is evaluated by difference. Calibration graphs were rectilinear for 2 µg mL-1 of Cr(VI) and 4 µg mL-1 of Cr(III). Detection limits were 18 ng mL-1 and 55 ng mL-1 for Cr(VI) and Cr(III), respectively. Tolerance limits for Cr(III), Fe(III), Mo(VI), Hg(II), Mn(II), V(V), Cu(II) and Cl- have been examined under dynamic flow injection analysis conditions. Results obtained by this method and by conventional spectrophotometry are compared. Results are presented for the analysis of synthetic mixtures and a sample of effluent water from a leather treatment plant.
Chromium(III) Chromium(VI) Spectrophotometry Interferences Method comparison Speciation

"Studies On Flow Injection Analysis With Sulfide Ion-selective Electrodes"
Analyst 1985 Volume 110, Issue 2 Pages 113-119
M. G. Glaister, G. J. Moody and J. D. R. Thomas

Abstract: The Orion Model 94-16A, EDT Research EES and EDT Research EES flow-through electrodes were tested and shown to yield near-Nernstian slopes of response between 1 µM and 0.01 M and 0.01 M S2-. Interference by H2O2 can be controlled by adding antioxidant buffer (4% of ascorbic acid in 2 M NaOH). Reconditioning of affected electrodes may be achieved by soaking in 0.1 M Na2S for 48 h and then polishing the membrane surface. For flow injection analysis a carrier stream (2.23 mL min-1) containing 5 µM-Na2S in a medium of 2% of ascorbic acid in 2 M NaOH was suitable for analysis of sewage effluent samples in a 12-cm x 1.3-mm flow tube. For determination of S2- in sewage, flow injection analysis was superior to direct potentiometry. Both the Orion Model 94-16 and EDT Research EES 'flow-through' electrodes yielded values for S2- similar to those obtained colorimetrically. Sulfide contents ranged from 0.1 to 17.8 ppm, the lower level relating to samples pre-treated with H2O2 as a recognized method of controlling adverse sulfidic species in effluent.
Sulfide Electrode Potentiometry Interferences Method comparison

"New Approach To The Simultaneous Determination Of Pollutants In Waste Water By Flow Injection Analysis. 2. Cationic Pollutants"
Analyst 1985 Volume 110, Issue 3 Pages 277-281
Angel R&iacute;os, M. Dolores Luque de Castro and Miguel Valc&aacute;rcel

Abstract: Similarity in the optimum values of the variables for Cu, Fe and Al in reversed-flow injection analysis (cf. Part I, Anal. Abstr., 1985, 47, 7H80) enabled the individual systems to be assembled into a single manifold with only minor loss in sensitivity. The insertion of several valves with different functions along the manifold expedited the spectrophotometric measurements, which were carried out at 575 nm. Simultaneous determinations on samples with ~1 to 6 µg mL-1 of added analytes gave an average error of ~±3.5%, the results agreeing well with those of AAS. Most cations in excess did not interfere, but EDTA, CN- and S2- did. This versatile system incorporated simple instrumentation and its consumption of reagent was low. The ease and rapidity of operation facilitated the routine monitoring of waste-water pollutants.
Copper Iron Aluminum Nitrite pH Spectrophotometry Interferences Method comparison Tecator

"Determination Of Sulfide Using Flow Injection Analysis With A Coated Tubular Solid-state Silver-sulfide Ion-selective Electrode"
Analyst 1988 Volume 113, Issue 6 Pages 885-889
Jacobus F. van Staden

Abstract: The electrode described previously (cf., e.g., Anal. Abstr, 1987, 49, 7J12) was activated by deposition of Ag2S as a fine membrane on the inner wall of the tubular cylinder, conditioned for >24 h in 0.1 M Na2S, and incorporated into a flow injection system containing an Orion 90-02 double-junction reference electrode. The performance of the electrode was evaluated by using 1 M KNO3 or sulfide antioxidant buffer solution as carrier stream, and a working range of up to 1 g L-1 was established for determination of S2- (injection volume 30 µL). Results compared favourably with those obtained with a commercial cascade mode electrode, and sensitivity was improved (detection limit 0.4 mg l-1). Mercury, Br-, I-, CN- and S2O32- interfered. The electrode was applied in the determination of S2- in effluents, and the coefficient of variation (n = 15) ranged from 0.9 to 1.8%. Recoveries of S2- added to water ranged from 96 to 104%.
Sulfide Electrode Electrode Potentiometry Interferences

"Spectrophotometric Method For The Determination Of Total Cyanide In Wastewater Samples"
Analyst 1988 Volume 113, Issue 8 Pages 1273-1276
Mary Drikas and Bryce I. Routley

Abstract: A sensitive spectrophotometric method is described for the detection of low cyanide levels in wastewaters. Wastewaters often contain sulphide and addition of lead carbonate is the recommended method for removal of sulphide interference. However, we have found that addition of lead carbonate is unsatisfactory. The addition of a stoicheiometric amount of lead to remove the sulphide interference, this amount being determined by titration with lead acetate using a redox electrode for end-point determination, is more satisfactory. The precision and recoveries (average 91%) obtained with this modified procedure were acceptable.
Cyanide, total Spectrophotometry

"Simultaneous Determination Of Total Iron And Chromium(VI) In Waste Water Using A Flow Injection System Based On The Sandwich Technique"
Analyst 1989 Volume 114, Issue 11 Pages 1465-1468
Alberto N. Araujo, Jose Luis F. C. Lima, Antonio O. S. S. Rangel, Julian Alonso, Jordi Bartroli and Raquel Barber

Abstract: The 'sandwich technique' involves injection of sample solution between two different reagent solution by means of an eight-port injection valve. The sample was injected between 0.1 M H2SO4 - aqueous ~1% ethanolic 0.05% 1,5-diphenylcarbazide and aqueous 20% hydroxylammonium chloride - aqueous ~1% ethanolic 0.1% 1,10-phenanthroline - ammonium acetate buffer. Two peaks were obtained at 526 nm, corresponding to the concentration. of Cr(VI) and total Fe (hydroxylamine reduces Fe(III) to Fe(II)). The range of application was 0.2 to 10 ppm of either metal, with detection limits of 0.18 ppm of Fe and 0.16 ppm of Cr(VI). The method was applied to waste water, and results agreed with those obtained by batch analysis.
Iron Chromium(VI) Spectrophotometry Dual reaction zones Buffer Peak analysis Sandwich technique Method comparison Simultaneous analysis

"Rapid Differential Flow Injection Of Phosphorus Compounds In Wastewater By Sequential Spectrophotometry And Inductively Coupled Plasma Atomic Emission Spectrometry Using A Vacuum Ultraviolet Emission Line"
Analyst 1990 Volume 115, Issue 8 Pages 1055-1058
Jamshid L. Manzoori, Akira Miyazaki and Hiroaki Tao

Abstract: Sample was injected into 0.5 M HNO3 as carrier stream, which was mixed with a reagent stream comprising (NH4)6Mo7O24 and NH4VO3 in HNO3. Phosphate was determined as molybdovanadophosphate by spectrophotometry at 470 nm, and the eluate was fed to an ICP-AES system for determination of total P at 177.499 nm. The calibration graphs were rectilinear for 200 µg mL-1 of P for both detection methods, and the limits of detection were 0.8 and 0.5 µg mL-1, respectively. Of several common ions examined, only Cr interfered in the spectrophotometric method. The coefficient of variation was 2.0% for 10 µg mL-1 of P (n = 11). Eighty samples per hour could be analyzed. The method was applied to treated sewage and metal-plating waste water.
Phosphorus Spectrophotometry Calibration Detection limit Interferences

"Determination Of Total Phosphate In Waste Waters By Online Microwave Digestion Incorporating Colorimetric Detection"
Analyst 1993 Volume 118, Issue 3 Pages 245-248
Kathleen E. Williams, Stephen J. Haswell, David A. Barclay and Gaynor Preston

Abstract: Up to 20 ppm of phosphate could be determined in the continuous-flow system with online passage of a 2 mL injected sample in a carrier flow (4.5 mL min-1) of aqueous 5% HNO3 through a PTFE tube (7.2 m x 0.5 mm) in a microwave digestion oven, cooling in a 7-m loop, merging with flows of 15 mM molybdate and 2.5% ascorbic acid (combined flow 2.4 mL min-1) for reaction in a 3-m PTFE coil and colorimetric detection at 690 nm. Rectilinear calibration was obtained for up to 20 ppm from a detection limit of 0.1 ppm and test recoveries of pure phosphate species were >99% except for pyrophosphates which were 66 to 68% but could be raised to 99% by addition of inorganic pyrophosphatase (E.C. 3.6.1.1). The coefficient of variation at 2 or 10 ppm (n = 10) were 5% in waste waters.
Phosphate Pyrophosphate Sample preparation Spectrophotometry Microwave Online digestion

"Determination Of Volatile Phenols By A Flow Injection Chemiluminescent Quench Method"
Analyst 1995 Volume 120, Issue 1 Pages 121-124
Hui-sheng Zhuang, Fan Zhang and Qiong-e Wang

Abstract: A 10 µg/ml p-chlorobenzenediazonium fluoriborate solution and a solution of phenols in 0.05 M NaHCO3 were both pumped continuously (1.5 ml/min) to a mixing valve and the merged stream was introduced into a glass flow cell (250 µL volume). Simultaneously, a solution of 0.01 M H2O2 in 0.05 M NaHCO3 was pumped (1.5 ml/min) and was injected into the flow cell. The chemiluminescence produced was measured. A diagram of the manifold used is given. Calibration graphs were linear up to 6, 5, 4.5 and 8 µg/ml of phenol (I), o-nitrophenol (II), p-cresol (III) and 2,4-xylenol (IV), respectively; the detection limits were 0.015, 0.02, 0.025 and 0.03 µg/ml, respectively. The RSD (n = 10) for 1 µg/ml of I was 3%. Recoveries of II, III and IV were 92-105%. The method was used to determine I-IV in polluted water. The results obtained agreed with those obtained by the 4-aminoantipyrine spectrophotometric method.
4-Cresol Phenol 2-Nitrophenol 2,4-Xylenol Chemiluminescence Quenching Method comparison

"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

"Speciation Of Nitrogen In Wastewater By Flow Injection"
Analyst 1996 Volume 121, Issue 1 Pages 13-17
A. Cerd&agrave;, M. T. Oms, R. Forteza and V. Cerd&agrave;

Abstract: For joint nitrite and nitrate determination, the sample was aspirated (0.36 ml/min) through a column of Amberlite XAD-7 resin before being mixed with a reductant stream (1.2 ml/min) containing 3 g/l hydrazine sulfate, 6 mg/l CuSO4, 1 g/l ZnSO4 and 20 g/l NaOH. The mixture was passed through a 2 m reaction coil maintained at 40°C; it was then injected into an aqueous carrier stream (1.2 ml/min), which was mixed with a reagent stream (1.2 ml/min) containing 20 g sulfanilamide and 0.5 g N-(1-naphthyl)ethylenediamine in 25 mL 37% HCl. The absorbance was then measured at 540 nm, from which the absorbance at 420 nm was subtracted. Nitrite was determined by the above procedure, except that the reductant stream was replaced by water. Nitrate was determined by difference. For total N determination, the sample (0.2 ml/min) was mixed with a stream (0.36 ml/min) containing 15 g/l alkaline potassium persulfate and 3.5 g/l sodium tetraborate. The mixture was passed through a 3 m coil and irradiated at 254 nm for 50 s. The irradiated sample was then treated as described above for joint nitrite and nitrate determination, except that the resin column was not used. Calibration graphs were linear up to 220, 240 and 1000 µM nitrite, nitrate and total N, respectively; detection limits were 2, 8 and 30 µM. The RSD (n = 10) were 1.5%, 2.3% and 3% for nitrite, nitrate and total N determination, respectively.
Nitrate Nitrite Nitrogen Spectrophotometry Amberlite Speciation

"Separation And Detection Of Condensed Phosphates In Waste Waters By Ion Chromatography Coupled With Flow Injection"
Analyst 1996 Volume 121, Issue 8 Pages 1089-1093
David J. Halliwell, Ian D. McKelvie, Barry T. Hart and Roger H. Dunhill

Abstract: Waste water was filtered and a portion (500 µL) of the filtrate was injected on to an Alltech Wescan Anion/R column (25 cm x 4.1 mm i.d.) packed with poly(styrene-divinylbenzene)trimethyl-ammonium anion exchanger. Elution (1.2 ml/min) was with 0.115 M KCl/1.32 mM Na4EDTA. The column effluent was directed into a stream of 8.9 mM ammonium molybdate in 1.4 M H2SO4 at a flow rate of 0.25 ml/min and the mixture was passed through a PTFE reaction coil (10 m x 0.5 mm i.d.) heated at 120°C. After passing through a Peltier cooler and a de-bubbler, the reaction products were mixed with a stream of 1.05 mM SnCl2/15.4 mM hydrazine sulfate in 0.52 M H2SO4 at a flow rate of 0.25 ml/min. Absorbance was measured at 690 nm. The calibration graphs were linear for 10 (detection limit) to 1000 µg/l orthophosphate and for 20 (detection limit) to 2000 µg/l pyrophosphate and triphosphate. Recoveries of pyrophosphate and triphosphate were 95-103%.
Phosphate HPIC

"Multicomponent Analysis By Flow Injection Using A Partial Least-squares Calibration Method. Simultaneous Spectrophotometric Determination Of Iron, Cobalt And Nickel At Sub-ppm Levels"
Analyst 1996 Volume 121, Issue 11 Pages 1609-1612
Carlos Moreno, Manuel P. M&aacute;nuel-Vez, Inmaculada G&oacute;mez and Manuel Garc&iacute;a-Vargas

Abstract: Sample (136 µL) was injected into a reagent stream (1 ml/min) of 0.02% 2,2'-di-pyridyl ketone picolinoylhydrazone/0.05% ascorbic acid in 0.02 M acetate buffer of pH 4.9 in a flow injection manifold (schematic shown). The mixture was passed through a 130 cm coil and the absorbance was recorded spectrophotometrically at 367, 410 and 385 nm, respectively, for Fe, Co and Ni with corresponding epsilon of 6640, 3890 and 5170. A partial least-squares calibration method was applied to the data in order to determine the Fe, Co and Ni concentrations in the sample. The method was applied to a washing solution used in an automotive factory and to a waste acidic mine effluent. Results obtained agreed well with those obtained by AAS or ICP-AES.
Cobalt Iron Nickel Spectrophotometry Method comparison Partial least squares Buffer

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

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

"Automated Determination Of Sulfide As Hydrogen Sulfide In Waste Streams By Gas-phase Molecular Absorption Spectrometry"
Analyst 1997 Volume 122, Issue 7 Pages 689-693
Les Ebdon, Steve J. Hill, Mohammad Jameel, Warren T. Corns and Peter B. Stockwell

Abstract: A continuous-flow vapor generation method for sulfide determination is described. A sulfide solution, stabilized in 25% sulfide antioxidant buffer (0.5 M NaOH/0.2 M NaBH4/0.2 M sodium citrate), was pumped (7.6 ml/min) and mixed with a stream (2.8 ml/min) of 0.6 M HCl in a gas/liquid separator. The H2S generated was purged from the solution by an air stream (200 ml/min) and introduced into a glass absorption cell, where the absorbance was measured at 200 nm. A diagram of the system used is given. The calibration graph was linear for up to 100 mg/l sulfide, the detection limit was 0.13 mg/l and the throughput was ~90 samples/h. Recoveries of added sulfide were 98-108%. Of 16 ions tested, only Cu, Pb, Zn and As interfered. The method was applied to waste water. The results obtained agreed with those obtained by titrimetry.
Sulfide Spectrophotometry Gas phase detection Method comparison Phase separator Interferences

"Simultaneous Determination Of Phosphate And Silicate In Waste Water By Sequential Injection Analysis"
Analyst 1997 Volume 122, Issue 10 Pages 1033-1038
F. Mas-Torres and V. Cerd&agrave;

Abstract: The method is based of the formation of yellow vanadomolybdophosphate and molybdosilicate, respectively, in addition to the use of large sample volumens. The mutual interference between both analytes was eliminated by selection of the appropriate acidity and by sample segmentation with oxalic acid. The calibration graph for phosphate and silicate is linear up to 12 mg L-1 P and 30 mg L-1 Si, respectively. The detection limits are 0.2 and 0.9 mg l-1. The method provides a throughput of 23 samples h-1 with a relative standard deviation of < 1.4% for phosphate and < 4% for silicate. The method was found suitable for the determination of these species in waste water samples. A sequential injection analysis system for the simultaneous determination of phosphate and silicate in waste water is proposed. The method is based on the formation of yellow vanadomolybdophosphate and molybdosilicate, respectively, in addition to the use of large sample volumes. The mutual interference between both analytes was eliminated by selection of the appropriate acidity and by sample segmentation with oxalic acid. The calibration graph for phosphate and silicate is linear up to 12 mg L-1 P and 30 mg L-1 Si, respectively. The detection limits are 0.2 mg L-1 P and 0.9 mg L-1 Si. The method provides a throughput of 23 samples h-1 with a relative standard deviation 1.4% for phosphate and 4% for silicate. The method was found to be suitable for the determination of these species in waste water samples.
Phosphate Silicate Spectrophotometry Simultaneous analysis Sequential injection Interferences pH

"Online Determination Of Sulfide By The Methylene-blue Method With Diode-laser-based Fluorescence Detection"
Analyst 1997 Volume 122, Issue 12 Pages 1555-1557
Michelle A. Spaziani, James L. Davis, Manisha Tinani and Mary K. Carroll

Abstract: The application of an inexpensive, compact, solid-state, fluorescence-based detector for flow injection analysis to the determination of sulfide by the 'Methylene Blue Method', viz., production of Methylene Blue (MB) via the oxidative coupling of sulfide with N,N-dimethyl-p-phenylenediamine (DMPD) in the presence of iron(III), is described. The use of fluorescence-based detection allows the reaction to be performed online under less corrosive, albeit sub-optimum, reaction conditions. The detector uses a 670 nm diode laser as the excitation source and inexpensive photodiodes as detector elements; a color filter (used to block scattered laser light) is the only other optical component of the detector. The fluorescence signal resulting from the MB formed online is linear over the range 0.75-15.0 mg L-1 injected sulfide, with a limit of detection of 0.08 mg L-1 injected sulfide when 9.0 M H2SO4 is used in the DMPD carrier stream, and 1-2 mg L-1 when less acidic carrier streams are employed, Use of this method for analysis of sulfide unknowns in aqueous solution and in a simulated waste water matrix demonstrates that unknown sulfide samples can be analyzed reproducibly. 5 References
Sulfide Fluorescence Detector Process control Low cost Laser diode Photodiode

"Flow Injection Potentiometric Determination Of Phosphate In Waste Waters And Fertilizers Using A Cobalt Wire Ion-selective Electrode"
Analyst 1998 Volume 123, Issue 7 Pages 1635-1640
Roland De Marco, Bobby Pejcic and Zuliang Chen

Abstract: Flow injection potentiometric (FIP) determinations of dihydrogen phosphate (H2PO4-) in fertilizers and waste waters were undertaken using a cobalt wire phosphate ion selective electrode (ISE). The Co wire electrode was used in the FIP determination of phosphate in a carrier containing 4 x 10^-2 mol L-1 potassium hydrogen phthalate (KHP) at pH 5. The FIP technique was validated for fertilizer and waste water samples against standard spectrophotometric methods of anal. FIP is a highly selective and accurate technique for the determination of phosphate in fertilizers [i.e., the FIP and spectrophotometric data compare to within a few percent (relative)]. A significant chloride interference occurs in waste water samples; however, this problem can be eradicated by using the chloride selectivity coefficient, chloride concentrations determined independently using ion-selective electrode potentiometry. The discrepancy between correlated FIP and spectrophotometric data for phosphate in waste waters is generally ±5% (relative). X-ray photoelectron spectroscopic and electrochemical impedance spectroscopic (EIS) results suggest that the Co oxide surface film of the electrode is dissolved in phosphate media, facilitating the corrosion process that regulates the response of the Co wire electrode. The EIS response of the Co wire electrode is dependent on both the pH and phosphate content of the solution A charge-transfer reaction mechanism, and accompanying Nernst equation, probably explain the phosphate response of the Co wire electrode.
Phosphate Electrode Electrode Potentiometry Apparatus Detector Method comparison Interferences

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

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

"Atomic Absorption Spectrometric Determination Using A Multipurpose Dialyser In A Flow Injection System"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 10 Pages 727-732
Jacobus F. van Staden and Cornelius J. Hattingh

Abstract: Industrial effluent was analyzed using a FIA system with a multipurpose dialyser unit (diagram given). The dialyser unit was a slightly modified Technicon AutoAnalyzer II unit (details given) with a Technicon premount dialysis C membrane between donor and acceptor channels. The donor channel was filled with sample and allowed to dialyse. The dialysate (75 µL) was channelled to the injection valve, then into the carrier stream and mixed in a 25 cm coil before transportation to a Varian AA-1275 flame AAS detector. This system was suitable for handling the marked variation in concentration levels present in industrial effluent. RSD was 0.3%; sample rate was 120/h.
Copper Spectrophotometry Dialysis Membrane

"Interference Removal For Cadmium Determination In Waste Water And Sewage Sludge By Flow Injection Cold Vapor Generation Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 10 Pages 1145-1149
Mar&iacute;a Liva Garrido, Riansares Mu&ntilde;oz-olivas and Carmen C&aacute;mara

Abstract: Cold vapor generation coupled to atomic absorption spectrometry using flow injection (FI-CVAAS) was evaluated as a rapid and simple method for the determination of Cd in wastewater and sewage sludge. Wastewater samples did not need any pre-treatment prior to anal. The sewage sludge was digested in a high pressure microwave oven to ensure good solubilization of the samples. Some elements in the sample (Cu, Pb, Ni, Zn) showed important interferences in the FI-CVAAS method. Elimination of such interferences by adding KCN to the borohydride solution is discussed. Validation of the method was achieved by analyzing a sewage sludge sample used in an interlab. exercise organized by the Water Research Center, UK, and by comparing the results with those obtained by electrothermal atomic absorption spectrometry (ETAAS) using a graphite furnace. Wastewater and sewage sludge samples were analyzed by both FI-CVAAS and ETAAS methods.
Cadmium Spectrophotometry Sample preparation Interferences Method comparison

"Sample Flow Velocity And Low Level Sodium Ion Measurement With The Glass Electrode"
Anal. Chem. 1975 Volume 47, Issue 13 Pages 2307-2309
Edgar L. Eckfeldt and William E. Proctor Jr.

Abstract: The accuracy is increased and time and volume of solution required for anal. are decreased when an insert is placed in the sensor bulb portion of a sodium [7440-23-5] ion analyzer to increase the flow velocity of the sample solution passing the sensor bulb surface. By this procedure the flow rate is decreased from 150 to <10 ml/min and as little as 0.1 ppb Na can be determined in water [7732-18-5].
Sodium Electrode Theory

"Indirect Atomic Absorption Determination Of Anionic Surfactants In Wastewaters By Flow Injection Continuous Liquid-liquid Extraction"
Anal. Chem. 1986 Volume 58, Issue 11 Pages 2265-2269
Mercedes Gallego, Manuel Silva, and Miguel Valcarcel

Abstract: The method is based on the continuous extraction of the ion pair, formed between the detergent and the sulfate of the 1,10-phenanthroline - Cu(II) complex, into isobutyl methyl ketone followed by determination of the Cu by AAS. A phase separator fitted with a PTFE porous membrane is incorporated into the flow injection apparatus. Optimum chemical and instrumental conditions are given. The calibration graph is rectilinear for 0.1 to 5.0 µg mL-1 and the coefficient of variation is 0.8% at the 1 µg mL-1 level (n = 11). The limit of detection is 45 ng mL-1. The method is highly selective and free from interference by non-ionic surfactants. The method is applied to the determination of anionic surfactants in waste waters and results agree well with those obtained by the methylene blue method.
Surfactants, anionic Spectrophotometry Sample preparation Interferences Complexation Method comparison Phase separator Solvent extraction Teflon membrane Indirect

"Automated Titrations Using A Discontinuous Programmed-flow Analyser"
Anal. Chem. 1989 Volume 61, Issue 18 Pages 2109-2116
Dennis P. Arnold, Russell M. Peachey, John D. Petty, and Denis R. Sweatman

Abstract: The technique of automated discontinuous programmed flow analysis is described and the operating principles and design of a working prototype instrument, employing syringe pumps driven by interchangeable cams, is discussed. Different cam profiles allow a number of direct reading or reagent addition methods, as well as both single- and dual-flow titrations. Results are presented for argentometric titrations of Cl-1 in water with anodized Ag micro-electrodes contained in two alternative mixer - sensor assemblies as detectors. Precision is generally better than 1% in the range 60 to 160 mg L-1 for analysis times of 30 s. Cycle times can range form 6 to 90 s with negligible sample carryover. Accuracy for waste water is ± 2 to 3%.
Chloride Electrode Automation Instrumentation Titrations Mixing chamber

"Nitroprusside And Methylene Blue Methods For Silicone Membrane-differentiated Flow Injection Determination Of Sulfide In Water And Waste Water"
Anal. Chem. 1992 Volume 64, Issue 1 Pages 36-43
Vlastimil Kuban, Purnendu K. Dasgupta, and John N. Marx

Abstract: A membrane gas permeation module using a silicone rubber tube (0.6 mm x 12 cm; Patto Products) was incorporated into a flow injection system (described). Hydrogen sulfide evolved from the acidified sample of water or waste water was pre-concentrated by permeation in a stationary alkali acceptor solution, before being subjected to either the nitroprusside or the methylene blue method to determine the sulfide present. The methylene blue method is ~30x more sensitive, and allows determinations at sub µg L-1 levels. The detection limit for the nitroprusside method was 2 µg L-1 for 12 mL samples pre-concentrated in the membrane system. The membrane is highly resistant to fouling and analysis of untreated waste water samples containing suspended solids, oil and grease is possible. Since the nitroprusside method uses less aggressive reagents than the methylene blue method, its use is recommended unless ultratrace determinations are essential. H2S evolved from an acidified sample is pre-concentrated by permeation in a stationary alkaline acceptor solution enclosed in a silicone rubber sample loop. Depending on the sample volume pre-concentrated, the applicable analysis range spans low µg/L to tens of mg/L for both methods. The methylene blue method is more sensitive by a factor of ~30 and actually permits practical determinations in the sub µg/L levels. The limit of detection (LOD) for the nitroprusside method is 20 µg/L for a 20 µL sample by conventional flow injection determination (no membrane, throughput 30 samples/h) and <2 µg/L for a 12 mL sample pre-concentrated in the membrane system (throughput 5 samples/h). The membrane is highly resistant to fouling and permits anal. of untreated wastewater samples bearing suspended solids, oil, grease, etc., without any pretreatment. No significant interference is observed with either chemical Although the nitroprusside chemical is less sensitive, it does not involve the use of concentrated aggressive reagents and is recommended unless ultratrace determinations are essential. Viable reaction mechanisms are proposed for both of these chemistries.
Sulfide Spectrophotometry Silicone membrane Interferences Ultratrace

"Online Membrane/liquid Chromatographic Analyzer For Pentachlorophenol And Other Trace Phenols In Wastewater"
Anal. Chem. 1992 Volume 64, Issue 19 Pages 2258-2262
Richard G. Melcher, Dave W. Bakke, and Glen H. Hughes

Abstract: The development and application of a unique membrane interface for selective extraction and concentration. of trace phenols in aqueous streams is described. Selectivity for the extraction of phenols is obtained by controlling the pH of the extraction media. Because the membrane used is non-porous, the interface can be used directly in a sample containing particulates and high concentrations. of dissolved inorganic material. A membrane/liq. chromatography analyzer was developed for use online at a wastewater treatment plant for the determination of dichlorophenol, trichlorophenol, tetrachlorphenol, and pentachlorophenol at low ppb levels in the plant effluents.
Pentachlorophenol Tetrachlorophenol Trichlorophenol 2,4-Dichlorophenol HPLC Membrane

"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

"Optical Fibre Sensor For Biological Oxygen Demand"
Anal. Chem. 1994 Volume 66, Issue 11 Pages 1841-1846
Claudia Preininger, Ingo Klimant, and Otto S. Wolfbeis

Abstract: The cited biosensor (illustrated) comprised a sensing membrane mounted at the tip of an optical fiber. The membrane consisted of an optically-transparent gas-permeable polyester support on which layers of tris[4,7-diphenyl-1,10-phenanthroline]ruthenium(II) perchlorate (an O2-sensitive fluorescent material), charcoal (as an optical isolator), yeast cells (Trichosporon cutaneum) immobilized in poly(vinyl alcohol) and a substrate-permeable polycarbonate membrane were sequentially placed. The sensor was incorporated in a continuous-flow system with a 150 W pulsed Xe light source and a photomultiplier as detector; a 480 nm interference filter was used to isolate the appropriate excitatory light and a 560 nm long-pass filter was used to collect the red fluorescence (λmax = 610 nm). The calibration graph was linear for a BOD of up to 110 mg/l for a glucose/glutamate standard and the detection limit was ~2-3 mg/l; the RSD was 4%. The response time was 5-10 min. The method was applied to untreated sewage plant effluents and the results correlated well with those obtained by the conventional dilution method.
Glucose Glutamate Biological oxygen demand Sensor Fluorescence Optical fiber Method comparison Immobilized cell Interferences

"Simultaneous End Sequential Determination Of Chromium(VI) And Chromium(III) By Unsegmented Flow Methods"
Fresenius J. Anal. Chem. 1985 Volume 322, Issue 5 Pages 499-502
Juan Ruz, Angel R&iacute;os, M. D. Luque de Castro and Miguel Valc&aacute;rcel

Abstract: Sexavalent Cr and Cr(III) were determined at the µg mL-1 level by reversed flow injection analysis by using three configurations to permit simultaneous (either the completely continuous monitoring of Cr(VI) or the converging zone method) or sequential determination. Absorbance of the Cr(VI) - 1,5-diphenylcarbazide complex was measured at 540 nm with a single detector before and after Ce(IV) oxidation of Cr(III), the level of the latter being obtained by difference. Sampling frequencies of 30 to 100 h-1 were achieved. Major interferents were found to be S2-, I-, Fe(II) and NO2-. The methods could be applied to the monitoring of Cr in natural and waste waters.
Chromium(III) Chromium(VI) Spectrophotometry Interferences Process control Tecator Reverse

"Online Sulfate Monitoring By Reversed Flow Injection Analysis And Alternating Reagent Injection"
Fresenius J. Anal. Chem. 1987 Volume 326, Issue 8 Pages 754-756
Jacobus F. van Staden

Abstract: A method for the online turbidimetric determination of BaSO4 is described diagrammatically. A solution (60 µL) containing 0.2 g of thymol, 4 g of gelatin and 20 g of BaCl2.2H2O in 2 l of 5 mM HCl, and an aqueous solution (100 µL) containing 40 g of EDTA, 7 g of NH4Cl and 57 mL of concentrated NH3 in 1 L are alternately injected at 30-s intervals into a flow (3.9 mL min-1) of waste water containing 200 mg L-1 of SO42- and the SO42- is determined spectrophotometrically at 540 nm. The limit of detection was 30 mg L-1, the coefficient of variation was <2% and 60 determinations per h could be performed.
Sulfate Turbidimetry Reverse

"Removal Of Interferences In The Spectrophotometric Determination Of Cyanide By Dialysis Using Flow Injection Analysis"
Fresenius J. Anal. Chem. 1988 Volume 331, Issue 6 Pages 620-622
E. Figuerola, A. Florido, M. Aguilar and J. de Pablo

Abstract: The sample was mixed with 0.1 M HCl (0.25 mL min-1) in a flow injection system with a 50 to 500-cm coil, and the HCN formed passed through a Millipore 1-GVHP09050 membrane into 10 mM NaOH (0.4 mL min-1), portions (136 µL) of which were then injected into a stream of NaH2PO4 buffer solution (pH 6.3) and mixed with Chloramine T and a pyridine - barbituric acid reagent (cf. Rios et al., Anal. Abstr., 1985, 47, 5B70) in 76- and 476-cm coils, respectively, before measurement of the absorbance of the combined solution (0.8 mL min-1) in a flow cell at 582 nm. Calibration graphs were rectilinear from 0.1 to 5 mg L-1 of CN-; the detection limit was 70 µg L-1 of CN-. In the determination (at 10 samples h-1) of 2.5 mg L-1 of CN-, the coefficient of variation was 0.8% (n = 12). In determination of 5 mg L-1 of CN-, there was no interference from a 100-fold molar excess of SO42- or NH4+, a 40-fold molar excess of Cu(II), Cd or Zn or a 10-fold excess of Br-, Cl-, S2- or SCN-, but a 100-fold molar excess of CO32-, a 60-fold molar excess of Co(II) or Fe(III) or a 40-fold excess of Ni did interfere. The method should be applicable to waste water.
Cyanide Spectrophotometry Dialysis Gas diffusion Interferences Millipore

"Continuous Micro-flow Monitoring Method For Total Mercury At Sub-ppb Level In Waste Water And Other Waters Using Cold Vapor Atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1988 Volume 332, Issue 7 Pages 745-749
Masashi Goto, Edison Munaf and Daido Ishii

Abstract: The sample stream (200 µL min-1) was mixed with a stream of aqueous 2% K2S2O8 containing 65 ppm of Cu(II) (100 µL min-1) before passing through a PTFE tube (27 cm x 0.5 mm) in which organic Hg was oxidized to Hg(II). The stream was then mixed with 3.4 M NaOH containing 2% of SnCl2, passed through a PTFE tube (4 cm x 0.5 mm), mixed with Ar (9.0 mL min-1) and passed through a PTFE reduction and extraction tube (60 cm x 1.3 mm). The resulting stream containing gaseous Hg was passed through a gas - liquid separator cf. Anal. Chim. Acta, 1982, 140, 179) from which the gaseous phase was passed, via a condenser for water vapor removal, to a 1.13 mL flow cell for the AAS determination of Hg at 253.7 nm. Calibration graphs were rectilinear from 0.5 to 5.0 µg L-1 of Hg as HgCl2 or methylmercury chloride; the detection limit was 0.1 µg l-1. In the determination of 3.0 µg L-1 of Hg, the coefficient of variation was 1.1% (n = 4). The response time was ~5 min. There was no interference from up to 10% of NaCl in solution or from COD (up to 600 mg l-1). The method was used to monitor laboratory waste water continuously for 6 h.
Mercury Spectrophotometry Interferences Phase separator

"Determination Of Cyanide In Waste Water By Flow Injection Analysis"
Fresenius J. Anal. Chem. 1989 Volume 333, Issue 7 Pages 719-720
G. Sch&ouml;ndorf and H. Engelhardt

Abstract: Waste water containing CN- is caused to react with Chloramine T in buffer solution under conventional flow injection conditions and the resultant solution is combined in a mixer and a coiled capillary with pyridine - barbituric acid before spectrophotometric determination. Detection limits are improved considerably by a reversed method in which the reagents are injected into the CN--containing stream. Calibration graphs are rectilinear for 0.01 to 6 ppm and for 0.002 to 1.5 ppm by normal and reversed flow injection analysis, respectively.
Cyanide Spectrophotometry Buffer Reverse

"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

"Matrix Effects In The Determination Of Mercury By Continuous Micro-flow Cold Vapor Atomic Absorption Spectrometry In Alkaline Medium"
Fresenius J. Anal. Chem. 1989 Volume 334, Issue 2 Pages 115-117
Edison Munaf, Masashi Goto and Daido Ishii

Abstract: The effects have been studied of various substances on the determination of 4.0 µg L-1 of Hg as described by Goto et al. (Anal. Abstr., 1989, 51, 10H32) with use of SnCl2 in aqueous NaOH to produce Hg0 vapor. There was no interference from 10 mg L-1 of Ni, Fe(III), Te(IV) or Pb(II); Ag, Pt(IV) and Se(IV) interfered slightly at 10 mg l-1, and Au(III) and Pd(II) interfered slightly at 1 mg l-1. Interference from >2 mg L-1 of S2- was eliminated by adding >200 mg L-1 of I-; however, I- interfered at concentration. 200 mg l-1. There was no interference from 700 mg L-1 of Br-, NO2- or NO3- or from 10% of NaCl, and little interference from up to 600, 500 and 100 mg l-1, respectively, of D-glucose, Na benzoate and cysteine. Interference was much less than when the reducing agent was Sn(II) in acid solution or NaBH4 in alkaline solution Recoveries of 1.0 to 3.0 µg L-1 of Hg added to waste water from a factory treating city refuse were 96 to 103%.
Mercury Spectrophotometry Interferences Volatile generation Volatile generation

"Ion-chromatographic Trace Analysis Of Mercury, Cadmium And Zinc By Post-column Derivatization With A Water-soluble Porphyrin"
Fresenius J. Anal. Chem. 1989 Volume 334, Issue 6 Pages 507-510
Daren Yan, Jingan Zhang and Georg Schwedt

Abstract: Sample solution was subjected to ion chromatography on a Nucleosil SA (10 µm) column (20 cm x 4 mm) with 0.5% NaCl solution in 1 mM tartrate (pH 4.3) as mobile phase (0.6 mL min-1). Post-column reaction with 10 µM-4,4',4'',4'''-(21H,23H-porphine-5,10,15,20-tetrayl)tetrabenzenesulfonic acid - 1 µM-4-(2-pyridylazo)resorcinol - 0.6% of NaCl - 32 mM borate buffer of pH 11.5 (0.3 mL min-1) was carried out in a T-shaped mixing cell, and detection was at 430 nm. Calibration graphs (injection volume 0.1 ml) were rectilinear for 0.002 to 0.8, 0.1 to 8 and 0.05 to 20 mg L-1 for Cd, Hg and Zn, respectively; corresponding detection limits were 0.5, 50 and 10 µg l-1. The method was successfully applied in the determination of these metals in waste water, a silicate sample and rice.
Mercury Cadmium Zinc HPIC Spectrophotometry Post-column derivatization Buffer Mixing chamber

"Enhancement Effect Of Iron Addition For The Decomposition Of Organic Mercury As Studied By Continuous-flow Analysis With Cold Vapor Atomic Absorption-spectrometric Detection"
Fresenius J. Anal. Chem. 1992 Volume 342, Issue 1-2 Pages 154-156
Edison Munaf, Toyohide Takeuchi and Hiroki Haraguchi

Abstract: Sample was injected into a carrier stream (200 µL min-1) for reaction with 2% K2S2O8 (50 muwl min-1) in a PTFE tube. The stream was mixed with a catalytic reagent stream (50 µL min-1) of FeCl3 solution (1 g l-1) before reaction with a reducing stream (100 µL min-1) of 2% SnCl2 in 3.4 M NaOH. The Hg vapor generated was transferred by an Ar flow for analysis by cold vapor AAS with detection at 253.7 nm. The response time was 5 min. The calibration graph was rectilinear from 0.5 to 5.0 µg L-1 of Hg and the detection limit was 0.16 µg l-1. The coefficient of variation was 1.5% (n = 4) for 4.0 µg L-1 of Hg; recoveries were 91 to 98%. The method was applied in the determination of total Hg in waste waters. Determination of total Hg by cold vapor atomic absorption spectrometry using continuous-flow anal. is described. Organic mercury compounds such as MeHgCl, EtHgCl, and PhHgCl were decomposed by K2S2O8 with addition of FeCl3 catalyst. The reducing agent used was SnCl2 in NaOH solution With 1,000 mg Fe/L added during the decomposition, MeHgCl and EtHgCl had a response similar to that of HgCl2. The method was used to determine total Hg in wastewater.
Ethylmercury Methylmercury ion Phenylmercury Spectrophotometry Sensitivity Catalysis

"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

"Determination Of Arsenic In The Presence Of High Copper Concentrations Using Flow Injection Analysis - Hydride[-generation] Atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1993 Volume 346, Issue 6-9 Pages 683-685
C. Schmidt and M. Bahadir

Abstract: Landfill waste water from polymer shredding waste of electrical cable (10 ml) was mixed with 5.5% hydroxylammonium chloride solution (1 ml) to reduce Cu(II) to Cu(I) and with 37% HCl (3 ml) and a KI-ascorbic acid reagent to reduce As(V) to As(III) and ppt. CuI and PbI2. After centrifugation, a 0.5 mL portion of the solution was injected into 4.35% HCl as carrier and the AsH3 generated with NaBH4 was determined by AAS. The solution contained 10 g/l of Cu(II), 0.15 g/l of Pb(II), 25 mg/l of Fe(III) and 0.4 g/l of Ni(II). Down to 1 µg/l of As could be detected in such solution
Arsenic Spectrophotometry Speciation Volatile generation Volatile generation

"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

"Two-step Solvent Extraction Flow Injection System For The Determination Of Anionic Surfactants By Spectrophotometry"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 4 Pages 416-419
Shihua Fan and Z. Fang

Abstract: An automated flow injection method is presented based on the official methylene blue (MB) method (Hein et al., Water and environmental analysis with the UV/Vis spectrometer Lambda 2 (Perkin-Elmer, 1992, Uberlingen). Samples (100 µL) were injected into the system manifold (diagram and details given) and transported by water carrier to merge downstream with buffered MB solution (preparation details given). CHCl3 was delivered by PTFE tubing (0.5 i.d. x 1 mm o.d.) and segmented with aqueous flow in a segmentor. The ion-pair formed in the aqueous phase was extracted into the organic phase whilst passing through an extraction coil. The organic phase was separated from the aqueous phase and merged with acid MB washing solution (preparation details given). Interferents were back-extracted into the aqueous phase which was then discarded. The CHCl3 phase was introduced into a flow cell and detection was at 652 nm. Calibration graphs were linear up to 6 mg/l SDS in aqueous solution; RSD were 4.6% (n = 7). Recoveries were 89-107% anionic surfactants. Results obtained for anionic surfactants in waste water samples agreed well with those obtained by the standard MB batch method.
Surfactants, anionic Spectrophotometry Sample preparation Automation Interferences Method comparison Organic phase detection Ion pair extraction Solvent extraction

"Coulometric Determination Of The Flow Rate Of Small Masses Of Substances. 2. Application To Online Measurement Of The EOX-parameter"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 6 Pages 582-588
M. Luitjens, H. Kupka, D. Gherban, E. Baumgarten

Abstract: A previously developed coulometric method (Ibid. 1993, 347, 87) has been coupled with a FIA system and applied to the analysis of the EOX-parameter extractable organic halogens (where X = Cl, Br and I). The titration curve was determined using the coulometric system for the determination of the adsorbable organic halogen (AOX) global parameter described in the previous paper (loc. cit.). The curve was then integrated into computer software which evaluated the time dependent signal. The flow rate can then be calculated (details given). For online analysis, water samples were mixed with hexane (1:40) with stirring for 1 h; flow rates were 1.4 and 0.1 ml/min for the aqueous and hexane phases, respectively. The phases were separated and hexane extracts were combusted at 700°C in Ar/O with a Pt/Pd catalyst (system details given). Recoveries were >70%; detection limit was 0.1 mg Cl/l. Applications include waste water and process water control.
Organics, halogenated Coulometry Computer

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

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

"Flow-through Stripping Chronopotentiometry For The Monitoring Of Mercury In Waste Waters"
Fresenius J. Anal. Chem. 1998 Volume 362, Issue 2 Pages 201-204
E. Beinrohr A, J. Dzurov A, J. Annus A, J. A. C. Broekaert

Abstract: A simple method for the determination of total mercury in waste waters is described. It makes use of a flow system incorporating a wall-jet cell equipped with a gold working electrode. The untreated sample is mixed on-line with the acidic carrier electrolyte which contains potassium permanganate and transforms the various species of mercury, especially elementary Hg, to Hg(II). The pre-treated solution enters the cell where mercury is deposited on the gold electrode. In the next step the deposit is stripped at constant current and the time corresponding to the dissolution of the deposit is obtained from the chronopotentiometric signal. The method enables it to determine and monitor Hg in the concentration range of 1 to 1000 wg/L in 5 min intervals.
Mercury Potentiometry Electrode

"Online Monitoring Of Nitrite In Fertilizer Process Streams, Natural And Wastewater Effluents With Sequential Injection Analysis"
Microchim. Acta 1998 Volume 129, Issue 1-2 Pages 33-39
Jacobus Frederick van Staden and Thomas Arnoldus van der Merwe

Abstract: A sequential injection system for the online monitoring of NO2- in fertilizer process streams, natural waters, and wastewater effluents is proposed. NO2- is diazotized in the SIA system with N-(1-naphthyl) ethylenediammonium dichloride to form a highly colored azo dye which is measured at 525 nm. The proposed system is fully computerized and is able to monitor NO2- at a frequency of 49 samples per h with a RSD of <2.7%. The calibration curve is linear ≤5 mg/L. The detection limit is 0.053 mg/L.
Nitrite Spectrophotometry Sequential injection Process monitoring Automation

"Sequential Determination Of Nickel And Copper In Waste Waters By Reversed Flow Injection Spectrophotometry"
Microchem. J. 1995 Volume 52, Issue 2 Pages 146-154
Wang P., Shi S. J. and Zhou D.

Abstract: Color reagent (30 µL) containing 0.05% dimethylglyoxime and 5 mM I2 solution was injected into a stream (1.48 ml) of NH3/ammonium citrate solution and carried to a dispersion coil (20 cm x 0.7 mm i.d.) and then to a second loop. Portions (100 µL) were injected into the sample stream (2 ml/min) which passed through a reactor (100 cm x 0.7 mm i.d.) and to the flow cell for detection of the Ni-dimethylglyoxime complex at 460 nm. The FIA manifold incorporated a two-way diverting valve enabling the process to be repeated for the determination of Cu using a color reagent containing 0.2% sodium diethyldithiocarbamate (I) in NH3/NH4Cl solution of pH 8.2 and a carrier containing 2 g/l EDTA and 5 g/l ammonium citrate. The calibration graphs were linear for 0.03-4 and 0.04-4 µg/ml Ni and Cu, respectively, with RSD of 0.53% and 0.75%, respectively. No detection limits are given. Tolerance limits for interfering species are tabulated. Sample throughput was 60/h. The results for reference materials agreed well with the certified values. The results for waste water agreed well with those obtained by AAS.
Copper Nickel Spectrophotometry Reverse Reference material Method comparison Dual detection Interferences

"Reagentless Flow Injection Determination Of Ammonia And Urea Using Membrane Separation And Solid Phase Basification"
Microchem. J. 1998 Volume 59, Issue 3 Pages 372-382
James R. Akse, John O. Thompson, Richard L. Sauer and James E. Atwater

Abstract: Flow injection analysis instrumentation and methodology for the determination of NH3 and ammonium ions in an aqueous solution are described. Using inline solid phase basification beds containing crystalline media, the speciation of ammoniacal N is shifted toward the un-ionized form, which diffuses in the gas phase across a hydrophobic microporous hollow fiber membrane into a pure-H2O-containing analysis stream. The two streams flow in a countercurrent configuration on opposite sides of the membrane. The neutral pH of the analysis stream promotes the formation of ammonium cations, which are detected using specific conductance. The methodology provides a lower limit of detection of 10 µg/L and a dynamic concentration. range spanning three orders of magnitude using a 315 µL sample injection volume Using immobilized urease to enzymatically promote the hydrolysis of urea to produce NH3 and CO2, the technique was extended to the determination of urea.
Ammonia Urea Conductometry Gas diffusion Immobilized reagent Microporous membrane Solid phase reagent

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

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

"Comparison Of Immobilization Procedures For Development Of An Electrochemical PPO-based Biosensor For Online Monitoring Of A Depuration Process"
Anal. Lett. 1994 Volume 27, Issue 9 Pages 1659-1669
Canofeni, S.;Di Sario, S.;Mela, J.;Pilloton, R.

Abstract: Polyphenol oxidase (PPO) derived from potato, mushroom and purified tyrosinase was membrane-immobilized by either cross-linking with BSA-glutaraldehyde, covalent immobilization upon a nylon net or PALL Biodyne membranes or physical entrapment (details given). The various biocatalysts were mounted onto the surface of a Clark electrode and covered with an outer dialysis membrane. Using FIA with a carrier of 0.1 M phosphate buffer of pH 6.5 at 2.4 ml/min, amperometric analyzes of catechol (I) and phenol (II) were performed. Calibration graphs and analytical performance data for the various sensor types are presented. Optimum performance was obtained with sensors prepared from tyrosinase immobilized upon a nylon net, with a linearity range of 1-10 mM I and II and a sensor lifetime of ~30 days. Applications of the sensors to the analysis of polyphenols in waste water from the production of olive oil are discussed.
Catechol Phenol Sensor Dialysis

"Determination Of Total Mercury In Soils, Waste-water And Sewage Effluents"
Anal. Lett. 1997 Volume 30, Issue 8 Pages 1579-1590
M. T. M. Zaki; M. A. Esmaile

Abstract: The cationic mercury(II)-1,10-phenanthroline binary chelate reacts with the acidic dye Thymol Blue (TB), in the pH range 5.2-7.0, to form an ion-pair extractable into chloroform. The effect of primary ligand and counter ion concentrations, pH, extraction solvent, extractability, standing time and co-existing ions has been thoroughly investigated. The molar absorptivity of the ion-pair, in chloroform, is 1.27 x 10(5) L mol-1 cm-1 at 420 nm. The calibration graph is rectilinear for 0.09-1.72 µg mL-1 of mercury. The sensitivity index of the method is 0.0002 µg Hg cm-2 and the detection limit is 0.018 µg mL-1 of mercury. The stoichiometry of the extracted ion-pair is 1:2:1 (Hg-Phen-TB). The developed method has been successfully used to determine total mercury in soils, waste water and sewage effluents. 23 References
Mercury Spectrophotometry Sample preparation Chelation Ion pair extraction Organic phase detection

"Preconcentration By Flow Reversal In Conductometric Sequential Injection Analysis Of Ammonium"
Electroanalysis 1996 Volume 8, Issue 4 Pages 387-390
M. T. Oms, A. Cerd&agrave;, Victor Cerd&agrave; *

Abstract: A 75 µL portion of standard ammonium ion (I) solution and 100 µL 0.05 M NaOH were aspirated into a holding coil (150 cm x 1.5 mm i.d.) and transferred to the base compartment of a diffusion cell (construction described). The NH4+ ions were separated from the upper compartment which contained 0.05 M H3BO3 with a gas permeable membrane (0.22 µm pore) and NH3, which diffused through the latter, was absorbed in the H3BO3 and transferred to a 20 µL flow-through conductivity cell (described) with additional H3BO3 held in a coil (150 cm x 1.5 mm i.d.). Calibration graphs (relative conductivity) were linear up to 120 and 180 mg/l of I, respectively, with 0.05 M and 0.1 M H3BO3, respectively. The detection limit of 1.5 mg/l with an RSD of 3%, was reduced to 0.1 mg/l with pre-concentration achieved by five successive sample flow reversals (discussed), but the linear range was reduced to 80 mg/l. The procedure was applied successfully to the analysis of ammonium ions in waste waters.
Ammonium Conductometry Sequential injection Preconcentration

"Torulopsis Candida-based Sensor For The Estimation Of Biochemical Oxygen Demand And Its Evaluation"
Electroanalysis 1996 Volume 8, Issue 7 Pages 698-701
S. Sangeetha, G. Sugandhi, M. Murugesan, V. Murali Madhav, Sheela Berchmans, R. Rajasekar, Sumathi Rajasekar, D. Jeyakumar, G. Prabhakar Rao *

Abstract: The cited micro-organism was grown in a broth and harvested by centrifugation. The isolated microbes were dispersed in phosphate buffer of pH 7 and immobilized on a cellulose nitrate membrane by adsorption on to the pores, which was effected by filtration of a 0.5 mL portion of the dispersion through the membrane under reduced pressure. The prepared membrane was coupled to a dissolved O2 sensor by means of dialysis membrane kept in position with an O-ring. The sensor was used in a FIA system with phosphate buffer as the carrier stream (25 ml/h). Amperometric measurements were made at an applied potential of -0.6 V vs. Ag/AgCl. Calibration graphs were constructed with standard solutions of glucose/glutamic acid, and were linear up to 500 mg/l, corresponding to a BOD value of 370 ppm. The sensor, which is intended for application to effluents, exhibited good stability and a fast response time.
Oxygen, biochemical Sensor Dialysis

"Photo-cured Ammonium And Hydrogen-ion Selective Coated-wire Electrodes Used Simultaneously In A Portable Battery-powered Flow Injection Analyzer"
Electroanalysis 1997 Volume 9, Issue 17 Pages 1331-1336
Peter W. Alexander*, Telis Dimitrakopoulos, D. Brynn Hibbert

Abstract: Nonactin and N,N-dioctadecylmethylamine ionophores, each in an epoxydiacrylate polymer, were photo-cured on silver wires (0.8 mm i.d.) and evaluated as ammonium and hydrogen (pH) coated wire electrodes. The photo-cured membranes prepared in this study exhibited excellent adhesion to the metal substrate and improved mechanical strength compared to PVC based membranes. The ammonium electrode exhibited a Nernstian response over a concentration range between 0.01 mM and 100 mM with a detection limit of 0.0005 mM. The ammonium electrode exhibited improved selectivity against most common interfering ions, including potassium compared to previous studies. The hydrogen selective electrode exhibited a near-Nernstian slope of 55.9±0.8 mV change/log a((H+)) between pH 4.0 and pH 11.0 in the steady-state mode. The ammonium and pH sensors each responded quickly reaching 90% of steady-state value in<5s, making these coated wire sensors ideal for flow injection potentiometry measurements. In the FIP mode, both the photo-cured ammonium and pH electrodes exhibited near-Nernstian responses of 49.2±1.0 mV change/activity decade and 50.2±0.4 mV change/log a((H+)), respectively, over a similar concentration range as in the steady-state mode. The photo-cured ammonium and pH electrodes were used simultaneously in the analysis of hydroponic nutrient solutions and waste water samples obtained from a local greenhouse grower in the flow injection potentiometric mode. 29 References
Ammonium pH Electrode Electrode Potentiometry Electrode Electrode Simultaneous analysis Portable Interferences

"Determination Of Urea And Ammonia Using Ion-pair Liquid Chromatography With Online Post-column Derivatization In An Enzymic Solid-phase Reactor"
J. Chromatogr. A 1985 Volume 325, Issue 1 Pages 255-263
H. Jansen, R. W. Frei and U. A. Th. Brinkman, R. S. Deelder and R. P. J. Snellings

Abstract: The HPLC - enzyme reactor system is shown diagrammatically. Urease was used to convert urea(I) into NH3, which was caused to react with phthalaldehyde(II) and the product was detected fluorimetrically. For the determination of I and NH3 in, e.g., I production solution or waste water, the sample was passed through a column (15 cm x 4.6 mm) of Polygosil 60-5 C18 with 0.03 M potassium phosphate buffer (pH 6.9) containing 5 mM Na octanesulfonate as mobile phase (1.15 mL min-1). The eluate was passed through a reactor containing the immobilized enzyme from where it passed through a coiled reactor where it was mixed with II. The fluorescent product was monitored at 455 nm (excitation at 340 nm). Calibration graphs for I and NH3 were rectilinear for up to 0.35 µg and detection limits were 20 and 15 ppb, respectively.
Ammonia Urea HPLC Fluorescence Immobilized enzyme Post-column derivatization

"Determination Of Dissolved Hexavalent Chromium In Industrial Waste Water Effluents By Ion Chromatography And Post-column Derivatization With Diphenylcarbazide"
J. Chromatogr. A 1991 Volume 546, Issue 1 Pages 335-340
Elizabeth J. Arar and John D. Pfaff

Abstract: A previously described method ('Dionex Technical Note', No 26, Dionex Corp., Sunnyvale, CA, 1990) for the ion-chromatographic determination of Cr(VI) as its complex with diphenylcarbazide was applied to industrial effluents. All samples were stored on ice and analyzed within 4 h of collection and again the next day. Aqueous samples were filtered and adjusted to pH 9 to 9.5 (optimum) before analysis. The method was not applicable to solid wastes. For waste water, recoveries were quantitative and no oxidation of Cr(III) and Cr(VI) occurred.
Chromium(VI) HPIC Filter pH Post-column derivatization

"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

"Improved Method For The Determination Of Manganese In Nuclear Power Plant Waters"
J. Chromatogr. A 1993 Volume 640, Issue 1-2 Pages 371-378
Archava Siriraks and John Stillian, Dennis Bostic

Abstract: Manganese was determined in nuclear power plant water by ion chromatography in a Dionex DX-300 system with pre-concentration. on a MetPac CC-1 column, separation on an IonPac CS12 column with 10 mM HCl/8 mM H3PO4 as eluent (1 ml/min) and cation micro-membrane suppression and conductivity detection with post-column derivatization with 0.4 mM pyridylazoresorcinol/1 M dimethylethanolamine/0.3 M NaHCO3 and detection at 530 nm. The detection limit was 90 pg of Mn (1-3 pg/ml); no calibration ranges or RSD are given.
Manganese HPIC Preconcentration Post-column derivatization Metpac

"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

"Phenol Oxidase-based Biosensors As Selective Detection Units In Column Liquid Chromatography For The Determination Of Phenolic Compounds"
J. Chromatogr. A 1994 Volume 675, Issue 1-2 Pages 65-78
Fidel Ortegaa, Elena Dom&iacute;ngueza, Elisabeth Burestedtb, Jenny Emn&eacute;usb, Lo Gortonb and Gy&ouml;rgy Marko-Vargab,*

Abstract: Five ways of incorporating monophenol monooxygenase in C paste and two ways of coating graphite rods with the enzyme were tested. The most stable and sensitive electrode was that formed by covalent attachment of the enzyme to rods. The 3 mm outside diameter rods were first activated by heating at 700°C for 92 s and treated with carbodiimide. The rods were dipped in a tyrosinase solution in 0.1 M phosphate buffer of pH 6, containing glutaraldehyde for 16 h at 4°C. For use, the electrodes were press-fitted into PTFE tubes so that only the flat end was exposed and mounted in a wall-jet flow-through amperometric cell. The catechol formed in the enzymatic reaction was detected at -0.05 V vs. Ag/AgCl, with use of a Pt counter electrode. For testing in the flow injection mode, the carrier was 0.1 M phosphate buffer of pH 6 at 0.7 ml/min. Calibration graphs were linear for 25 µL injections from 10 nM- to 20 µM-catechol, with a detection limit of 2.3 nM. The electrode was applied to the analysis of waste water (details given).
Phenols LC Electrode Electrode Electrode Sensor

"Continuous-flow Determination Of Aqueous Sulfur By Atmospheric-pressure Helium Microwave-induced Plasma Atomic-emission Spectrometry With Gas-phase Sample Introduction"
Spectrochim. Acta B 1995 Volume 50, Issue 4-7 Pages 393-403
Taketoshi Nakahara*, Toshio Mori, Satoru Morimoto

Abstract: The borosilicate-glass gas-liquid separator described previously (J. Anal. Atomic Spectrom., 1992, 7, 211) was used with a Tokyo Rikakikai MP-3 microtube peristaltic pump, a laboratory-constructed Beenakker-type water-cooled TM010 microwave cavity and a N2-purgeable Ebert-type plane-grating far-UV monochromator (cf. Bunko Kenkyu, 1989, 38, 205). The sample solution stream (containing sulfide or sulfite) merged with a stream of 1 M HCl, the evolved H2S or SO2 was swept from the gas-liquid separator to the microwave-induced plasma by a stream of He carrier/plasma gas and the emission intensity at 180.73 nm was integrated over 10 s in triplicate. The detection limits for H2S and SO2 introduction were 0.13 and 1.28 ng/ml of S and the background equivalent concentrations were 20.9 and 62.2 ng/ml of S, respectively, and the calibration graphs were linear over approximately four decades. The RSD (n = 10) at 10 and 100 ng/ml of S with H2S introduction and at 40 and 400 ng/ml of S with SO2 introduction were 3.21, 1.13, 3.00 and 1.42%, respectively. The method was applied to determine sulfide in waste water and sulfite in wine.
Sulfide Sulfite Sulfur Spectrophotometry Volatile generation Volatile generation

"Continuous Determination Of Cyanide In Waste Water With Ion-selective Electrode And Gas - Liquid Separation"
Anal. Sci. 1986 Volume 2, Issue 3 Pages 271-274
K. NAGASHIMA, H. HORIE and S. SUZUKI

Abstract: The sample is mixed (at 4 mL min-1) with 5 mM Bi(NO3)3 in acetate buffer solution of pH ~5 (at 1 mL min-1), and the mixture is then passed through a gas - liquid separator. The HCN produced diffuses through a PTFE membrane (0.80 µm pore size) into 0.02% NaOH solution (flowing at 24 mL h-1), and CN- is determined in this solution with a CN--selective electrode (Denki Kagaku Keiki Co., model CN 7002) vs. the SCE. The response time is ~1.3 min for 0.1 mM CN-. The limit of detection is 0.1 µM-CN- (2.6 ppb), and the calibration graph is rectilinear for 1 µM to 1 mM. A diagram of the flow system is given.
Cyanide Electrode Phase separator Teflon membrane

"Continuous Micro Flow Analysis System For Monitoring Total Mercury At Sub-ppb Level In Wastewater"
Anal. Sci. 1988 Volume 4, Issue 1 Pages 87-90
M. GOTO, S. KUMAGAI and D. ISHII

Abstract: A sample stream pumped continuously at 180 µL min-1 was mixed with 4.5 M H2SO4 flowing at 23 µL min-1 and then with 3% K2S2O8 solution at 17 µL min-1. Reduction of Hg(II) by 4% SnCl2 solution in 1.2 M HCl, flowing at 17 µL min-1, to Hg0 was followed by extraction into an Ar stream (7.5 mL min-1). The Hg vapor was dried and passed through a photometric flow cell (40 mm optical path) and the absorbance at 253.7 nm was recorded continuously. The detection limit for Hg was 0.15 µg L-1. Determination of Hg in waste water was successful, and the slow reagent flow rates used yielded only 350 mL of waste liquid per day.
Mercury Spectrophotometry Phase separator PPB

"Simultaneous Determination Of Total Phosphorus And Total Nitrogen By Flow Injection System"
Anal. Sci. 1989 Volume 5, Issue 2 Pages 235-236
M. AOYAGI, Y. YASUMASA and A. NISHIDA

Abstract: A flow injection system, the Sumigraph NP-2500, is described (diagram given) and conditions are tabulated for determination of total P and total N in a single sample. The method is based on digestion of the sample in dual capillary digestors with S2O82- for P and S2O82- - NaOH for N, and subsequent detection of PO43- and NO3- independently of one another in an acidified solution of ammonium molybdate containing malachite green (C. I. Basic Green) at 650 nm. In general, results agreed with those obtained by an official method. The method was applied in the determination of total P and total N in industrial waste water; analysis took 5 min. The coefficient of variation (n = 10) for 10 ng mL-1 of N was 0.9%.
Phosphorus Nitrogen, total Sample preparation Spectrophotometry Method comparison Standard method

"Digestion Method For The Determination Of Mercury In Continuous Micro-flow Analysis"
Anal. Sci. 1990 Volume 6, Issue 2 Pages 313-314
E. MUNAF, T. TAKEUCHI, M. GOTO, H. HARAGUCHI and D. ISHII

Abstract: Digestion of mercury, in sample or standard solution, with 10 M HCl, 10 M HNO3 and 10 M H2SO4 was studied. Total Hg was determined by AAS at 253.7 nm as described previously (Anal. Abstr., 1989, 51, 10H32). The response with H2SO4 digestion was only 85% of that obtained with digestion with HNO3, HCl or mixtures of these acids. In the analysis of waste water, maximum absorbance of Hg was observed with 0.1 M HCl digestion.
Mercury Sample preparation Spectrophotometry Intermittent pumping

"Online Pre-treatment With Cobalt(III) Ion For The Determination Of The Total Mercury By Cold Vapor Atomic-fluorescence Spectrometry Coupled With Flow Injection Analysis"
Anal. Sci. 1992 Volume 8, Issue 1 Pages 93-95
H. TANAKA, E. YAMAMOTO, H. MORITA and S. SHIMOMURA

Abstract: The modification of the method described previously by Sugimoto et al. (Bunseki Kagaku, 1990, 39, 251) in which organic and inorganic Hg was oxidized by Co(III) before measurement in the flow injection analysis system was presented. Since storage of Co(III) in aqueous solution posed many problems, an electrolytic cell was incorporated into the system in which Co(III) were generated by oxidation of Co(II). Recoveries of 99.6 to 107.9% were obtained from the addition of 100 µg L-1 of methylmercury chloride to waste water samples. An electrolytic cell in which Co(III) is generated continuously by oxidation of Co(II) is incorporated in a cold vapor atomic fluorescence spectrometer-flow injection analysis system for online oxidation of organic-bound Hg. The system is used for analysis of aqueous media for total Hg.
Mercury Methylmercury ion Fluorescence Interferences Electrochemical reagent generation

"A Novel Method For The Online Room-temperature Hydrolysis Of Hydrophobic Organic Phosphates Using A Cooperative Action Of Sodium Dodecyl Sulfate, Acid And UV-irradiation"
Anal. Sci. 1998 Volume 14, Issue 4 Pages 815-817
Yoshihiko IKEGUCHI and Hiroshi NAKAMURA

Abstract: In this communication, we therefore describe the finding that some hydrophobic organic phosphates are easily decomposed in an acidic medium containing sodium dodecyl sulfate, under UV-irradiation, without heating or any oxidizing agent added in solutions. The new decomposition system was evaluated by measuring orthophosphate liberated from organic phosphates in a flow injection system, in which a phosphomolybdic acid reaction and then a thiamine-thiochrome fluorescent reaction18 occurred.
Organic phosphates Fluorescence Surfactant Photochemistry UV reactor

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

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

"Studies On The Determination Of Sulfide Using N,N-diethyl-p-phenylenediamine"
Anal. Proc. 1983 Volume 20, Issue 12 Pages 609-622
M. O. Babiker, J. A. W. Dalziel, B. Law, J. R. Joyce, T. S. Bal, C. P. Goddard, M. Japp, I. J. Humphreys, P. J. Hobbs, P. Jones, L. Ebdon, S. J. Lyle, N. Za'tar, M. G. Batham and C. F. Simpson

Abstract: Two techniques, i.e., continuous-flow analysis with air segmentation (Carlo Erba model 1510) and flow injection analysis (Tecator FIAstar model 5001), for automating the determination (cf. Kloster and King, J. - Am. Water Works Assoc., 1977, 69, 544) are outlined. A suitable medium for stabilization of the colloidal suspension of ZnS is described. Results obtained by the flow injection method are slightly better with respect to speed (180 samples h-1) and detection limit (10 µg L-1 of S2-), but have slightly lower precision than those obtained by the segmentation technique. The method is intended for use in analysis of natural and waste waters.
Sulfide Spectrophotometry Tecator

"Membrane Introduction - Ion-trap Mass Spectrometry For The Determination Of Volatile Organics In Aqueous Effluents"
Anal. Proc. 1995 Volume 32, Issue 1 Pages 7-9
Colin S. Creaser and James W. Stygall

Abstract: A membrane interface fitted to an ion trap mass spectrometer has been used to detect and quantify volatile organic compounds present in aqueous samples at low ppbv levels. Alternate electron chemical ionization and tandem mass spectrometric scan routines were applied to the analysis of aqueous effluent samples.
Acetone Acetophenone Toluene Mass spectrometry Membrane

"Quantification Of BTEX Compounds In Model Effluent Systems Using Flow Injection Diode-array Spectrophotometry And Multivariate Calibration"
Anal. Proc. 1995 Volume 32, Issue 12 Pages 507-510
Kevin N. Andrew and Paul J. Worsfold

Abstract: A flow injection spectrophotometric method with multivariate calibration for quantification of BTEX compounds [benzene, toluene (I), ethylbenzene (II) and o-xylene (III) in effluents is investigated. Sample (200 µL), spiked with appropriate amounts of I, II and III was injected into a carrier stream of water (2.3 ml/min) of a flow injection system (schematic shown) and mixed with a stream of hexane (0.36 ml/min). The merged streams were carried to a PTFE microporous membrane solvent extraction cell and the extracted hexane layer was pumped to a silica flow cell (18 µL; 1 cm path length). The absorbance of the solution was measured at 2 nm intervals over the range 200-300 nm vs. a water reference. First- (FD) and second-derivative (SD) spectra were calculated with three-point wavelength smoothing, using the Savitsky-Golay algorithm. The absorbance of FD and SD spectra at 206 mm was linear up to 20 mg/l of pure I, II and III. The FD and SD spectral data were modeled using stepwise multiple linear regression, principal components regression and partial least-squares regression. Predictions of individual analyte concentrations in test samples produced prediction errors ranging from 8.5% for III to 45.8% for I. The lowest prediction errors (7%) were produced when calibrating the three compounds as a single component.
Benzene Ethylbenzene Toluene 2-Xylene Spectrophotometry Spectroscopy Spectroscopy Chemometrics Multivariate calibration Teflon membrane

"Enhanced Ion Chromatography With Sequential Flow Injection Analysis. Determination Of Common Anions And Nitrite"
Am. Environ. Lab. 1998 Volume 10, Issue 2 Pages 6-7
Karmarkar, S.V.

Abstract: Nitrite and F-, Cl-, NO3- Br-, HPO42-, SO42- were determined in wastewater, , groundwater and surface water samples by enhanced ion chromatography with sequential flow injection anal.
Fluoride Chloride Nitrate Bromide Sulfate Nitrite HPIC Sequential injection

"USEPA Regulation Of FIA Methods For NPDES And NIPDWR Monitoring Of Waters And Wastes"
Am. Lab. 1988 Volume 20, Issue 9 Pages 42-49
Ranger, C.B.

Abstract: A review with no references on EPA-approved flow injection analysis methods for the analysis of water and wastewater in compliance with the National Pollution Discharge Elimination System and the National Interim Primary Drinking Water Regulations.
Water Review Standard method

"Progress In Water Quality Control: Methods In Continuous Micro-flow And Flow Injection Analysis"
Analusis 1991 Volume 19, Issue 2 Pages i27-i31
SERIZOT P.

Abstract: The cited methods are examined and compared, and their advantages and disadvantages are discussed. The methods allowed the quality control of waste water with minimum automation. The efficiency and cost-effectiveness of the techniques are demonstrated. The choice of technique varied according to specific needs, control conditions requested and priorities peculiar to each laboratory.
Automation Low cost

"The Continuous Determination Of Filtered Chemical Oxygen Demand With Potassium Dichromate By Means Of Flow Injection Analysis"
Bull. Chem. Soc. Jpn. 1982 Volume 55, Issue 4 Pages 1033-1038
Takashi Korenaga

Abstract: A useful method, based on the principle of flow-injection analysis, whose flow system is physically analyzed to operate the apparatus, is proposed for the continuous and rapid determination of chemical-oxygen demand (COD) as a dichromate value in organic-waste-water samples. Potassium dichromate in sulfuric acid (1+2) is pumped as an oxidizing and spectrophotometric reagent stream, and D-glucose is successfully used as a standard substance for COD. A redox reaction between potassium dichromate and organic COD substances is carried out at 100°C in the poly(tetrafluoroethylene) tubing (0.6 mm i.d. x 50 m) of the system. The peaks, obtained at 445 nm in the recordings, show a good reproducibility over a wide range of COD values. A sampling rate of 10 samples per hour is achieved even when the residence time is 30 min. The precision with this method is 1.3%. Chloride up to 200 mg dm-;3 does not interfere with the determination even if silver or mercury salts are not added.
Chemical oxygen demand Spectrophotometry Heated reaction Interferences

"Flow Injection Analysis Of Chemical Oxygen Demand In Waste Waters From Laboratories"
Bunseki Kagaku 1980 Volume 29, Issue 8 Pages 497-501
KORENAGA Takashi IKATSU Hisayoshi

Abstract: A method based on the principle of flow injection analysis (FIA) is proposed for the determination of chemical oxygen demand (COD) in waste waters from laboratories containing large amounts of organic COD substances. The FIA apparatus was constructed of commercially available parts for high performance liquid chromatography. Polytetrafluoroethylene tubing (0.5 mm i.d.) was used for a reaction chamber and mixing coils as well for connections between the assemblages. By using test solutions including glucose as a standard material for COD, operating conditions and parameters for the FIA method were examined and fixed as follows; both of 4.9 x 10^<-4> M potassium permanganate and 6.7 % sulfuric acid solutions were separately pumped up with a double reciprocating micro-pump and merged into a carrier stream. At just before the merging place, a 20 µl of sample solution was injected into the flow of sulfuric acid solution. The sample mixed with the carrier solutions was passed through a boiling water-bath and led to a flow cell for the absorbance measurements at 525 nm. The absorbances were continuously recorded with time. The peaks in the recordings showed good reproducibility at a concentration range of (24-220) mg COD l^<-1>. The detection limit and precision confirmed with this method were 10 mg l^<-1> and 0.5 %, respectively. Chloride ion up to 7000 mg l^<-1> did not interfere with the COD determination without adding silver sulfate. By the present method, properly diluted waste water samples were analyzed at a sampling rate of 30 samples per hour and the results were compared with those obtained by the JIS method. Both of the methods gave the same results within an error range of ±30 %.
Chemical oxygen demand Spectrophotometry Heated reaction

"Fully Automated System For Continuous Monitoring Of Chemical Oxygen Demand By Flow Injection Analysis"
Bunseki Kagaku 1982 Volume 31, Issue 3 Pages 135-141
Takashi KORENAGA, Hisayoshi IKATSU

Abstract: A fully automated system has been developed for the continuous determination of chemical oxygen demand (COD) in aqueous environmental samples by flow injection analysis (FIA). Both of a 1 mM potassium permanganate solution and 10% sulfuric acid solution containing 20% phosphoric acid are separately pumped up with a double reciprocating micro-pump at respective flow rates of 0.2 mL min-1 and merged into a carrier stream. A 30 µL of sample is injected into the flow of acid solution with an automatic sampling valve at an interval of 8 min and then mixed with the carrier solutions. The mixture is passed through a reaction manifold made of polytetrafluoroethylene tubing (0.5 mm i.d. x 50 m), which is immersed in a thermostated bath involving corn oil at 100°C. After reaction, the resulting solution is led into a spectrophotometric detection at 525 nm and COD values with this method are determined by using peak heights in the recordings. The FIA system is simple and has the following advantages; (i) quantities of reagents and waste are small, (ii) continuous monitoring is possible since (78) samples are analyzed for an hour, and (iii) chloride ion up to 200 mg L-1 does not interfere with the determination. The system was successfully applied to the COD measurements of various industrial waste water samples, and to the continuous monitoring of COD in waste water from laboratory of university.
Chemical oxygen demand Spectrophotometry Automation

"Automated System For Total Phosphorus In Wastewaters By Flow Injection Analysis"
Bunseki Kagaku 1984 Volume 33, Issue 12 Pages 683-686
Korenaga, T.;Okada, K.

Abstract: A 0.31 mL sample is injected into a stream (1.2 mL min-1) of S2O82- solution, which then passes through a heating coil at 120°C before merging with a stream (0.2 mL min-1) of acidic molybdate solution The stream passes through a further heating coil at 75°C, and its absorbance is monitored at 880 nm. The response is rectilinear for up to 10 mg L-1 of P, the limit of detection is 0.01 mg l-1, and the sampling rate is 10 h-1. The coefficient of variation (n = 10) ranged from 0.3 to 1%. Results for various effluents agreed with those by the conventional manual method.
Phosphorus Spectrophotometry Heated reaction

"Continuous Monitoring Method Of Total Phosphorus In Wastewater Using Continuous Micro Flow Analysis"
Bunseki Kagaku 1988 Volume 37, Issue 1 Pages 52-55
Goto, M.;Nishimura, M.;Tominaga, T.;Ishii, D.

Abstract: The sample stream is mixed with a solution containing peroxydisulfate in dilute H2SO4; both solution are pumped at ~60 µL min-1 into a mixing joint, and then into a PTFE reaction tube (4 m x 0.64 mm) in an aluminum block bath at 120°C. A Pt wire (0.2 mm diameter) is inserted in the tube as catalyst for the oxidation reaction. All condensed phosphate and organic P compounds are converted into PO43- in the reaction. The stream carrying PO43- is mixed with a stream of molybdate and malachite green (C. I. Basic Green 4) to form a colored ion associate, the absorbance of which is measured at 600 nm in a flow cell.
Phosphorus Spectrophotometry Catalysis Heated reaction

"Continuous Monitoring Method Of Total Nitrogen In Wastewater Using Continuous Micro Flow Analysis"
Bunseki Kagaku 1988 Volume 37, Issue 1 Pages 47-51
Goto, M.;Murofushi, S.;Ishii, D.

Abstract: The waste-water sample and a solution of 0.6 M NaOH containing 1.8% of K2S2O8 are pumped at 100 and 50 µL min-1, respectively, through a mixing joint. Reaction takes place in a PTFE tube (8 m x 0.5 mm) in an aluminum block at 150°C. A Pt wire (diameter 0.2 mm) is inserted in the reaction tube as catalyst. All N species (e.g., NH4+, NO2-, and organic N) are converted into NO3-. The flowing solution then mixes with 0.62 M HCl at 50 µL min-1 before entering a flow cell where absorbance is measured at 220 nm.
Nitrogen, total Spectrophotometry Catalysis Heated reaction

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

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

"Flow Injection Spectrophotometric Determination Of Trace Amounts Of Cyanide Ion With 4-nitrobenzaldehyde And 2-dinitrobenzene On The Basis Of Catalytic Effect"
Bunseki Kagaku 1991 Volume 40, Issue 2 Pages T41-T46
Sakuragawa, A.;Kinoshita, Y.;Okutani, T.

Abstract: Sample (100 µL) was injected into a 0.01 M NaOH stream and mixed with a stream of ethylene glycol monomethyl ether (I) and then merged with a reagent solution containing equal amounts of 0.2 M 4-nitrobenzaldehyde - I and 0.15 M 2-dinitrobenzene - I. Absorbance of the solution was measured at 555 nm. The calibration graph was rectilinear for 10 ppb of CN-. The coefficient of variation was 1.2% (n = 10) for 50 ppb of CN-. The method was used in the analysis of waste water.
Cyanide Spectrophotometry Catalysis PPB

"Development Of A Continuous Monitoring System For The Determination Of Total Mercury Based On Gas - Liquid Separation Using Coaxial Microporous Tubing"
Bunseki Kagaku 1992 Volume 41, Issue 1 Pages 17-22
Takashi KORENAGA, Miyoko IZAWA, Hideo NOGUCHI, Teruo TAKAHASHI

Abstract: A gas - liquid separator (diagram presented) consists essentially of a length of micro-porous PTFE tubing (0.9 mm i.d., 2 mm o.d., porosity 62%, pore size 0.8 µm) through which the sample solution - alkaline reagent - reduction reagent stream passes, surrounded by a PTFE tube (3 mm i.d., 4 mm o.d.). The absorbance of the Hg vapor is measured in a cell (15 cm x 2.2 cm i.d.). The calibration graph is rectilinear up to 80 µg L-1 of Hg, and the detection limit is 0.08 µg l-1. The coefficient of variation (n = 5) at 40 µg L-1 was 0.8%. The method was applied to laboratory waste water. To determine total Hg at low levels in wastewater, a continuous monitoring system was developed in which coaxial microporous PTFE tubing was incorporated in a gas-liq. separator for FIA. For determination of total Hg by cold vapor atomic absorption spectrometry (AAS), the catalytic effect of Cu(II) on the reductive decomposition of organomercury was utilized together with Sn(II) reduction in alkaline solution. To design the system, the characteristics of Hg evolving through microporous PTFE tubing were first investigated by cold vapor AAS using the Au amalgamation technique. Then the continuous-flow (CFA) and FIA systems were constructed and operated. The calibration curve was linear at 80 µg/L and 100 µg/L and the detection limit was 0.08 µg/L and 0.5 µg/L for CFA and FIA systems, respectively. The relative standard deviation (n=5) was 0.8% for 40 µg/L for FIA system. Total and inorganic Hg in wastewater from chemical labs. could be measured continuously by the system.
Mercury Spectrophotometry Phase separator Volatile generation Catalysis Amalgamation Volatile generation

"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

"The Synergistic Catalytic Effect Of Metal-cations On Kinetic Reactions And Its Application To Determination Of Iron Oxidation-states"
Chem. Anal. 1995 Volume 40, Issue 5 Pages 815-821
Ronghuan, H.;Jianhua, W.

Abstract: Iron(II) and iron(III) catalyzed hydrogen peroxide/chromotropic acid kinetic reactions were studied by the stopped FIA technique. The concept of the synergistic catalytic coefficient (D) was defined. By introducing this coefficient into the previously established procedure for the simultaneous determination of a binary mixture of metal cations in a kinetic reaction, the deviation of the absorbance from the additivity rule could be effectively eliminated, and the linear concentration ranges were enlarged. The selectivity of the kinetic systems, in addition, was also improved remarkably. The iron oxidation states in wastewater and several simulated samples have been determined. The results are satisfactory. (9 references)
Iron(2+) Iron(III) Spectrophotometry Catalysis Kinetic Stopped-flow Speciation

"Flow Injection Analyser For Chemical Oxygen Demand Using Potassium Permanganate"
Chem. Biomed. Environ. Instrum. 1980 Volume 10, Issue 3 Pages 273-288
Takashi Korenaga

Abstract: An apparatus for measuring chemical oxygen demand (COD) in industrial waste water, based on the principle of flow injection analysis (FIA), is described. The apparatus is simple and inexpensive and constructed by components, such as a double plangent pump, sampling valve, flow cell, spectrophotometer and recorder, commercially available for high performance liquid chromatography. Polytetrafluoroethylene (Teflon) tubing is used for mixing coils and transmission lines. The operating conditions are determined by using glucose as the standard COD substance. The peak heights obtained for various concentrations of aqueous glucose solutions correspond to their manual COD values obtained by the JIS (Japan Industrial Standard) method.
Chemical oxygen demand Spectrophotometry Standard method Low cost Method comparison

"Amberlite XAD-2 Resin Microcolumn Coupled Online To A Flow Injection Approach For The Preconcentration, Cleanup And Determination Of Trace Phenols In Waters"
Gaodeng Xuexiao Huaxue Xuebao 1997 Volume 18, Issue 10 Pages 1621-1623
Song, W.L.;Wang, L.S.;Zhi, Z.L.

Abstract: A novel and expeditious approach for direct determination of phenols in water and waste water based on solid-phase extraction coupled to a flow injection analysis (FIA) manifold is described. The method employs online pre-concentration of phenols using a 3 cm X 3 mm column packed with Amberlite XAD-2 resin. The phenols are subsequently eluted from the resin into a flowing system with an alkaline solution and quantified spectrophotometrically as the products of reaction with 4-aminoantipyrine (4-AAP) system. The sensitivity offered by the procedure was higher by a factor of pH=13 than that provided by a conventional FIA method. 5 References
Phenols Spectrophotometry Sample preparation Solid phase extraction Amberlite Resin pH Preconcentration

"Online Sample Preparation With Flow Injection Analysis: Avoiding Additional Preparation Steps"
Chem. Rundsch. 1987 Volume 40, Issue 11 Pages 11-NA
Winter, B.

Abstract: As illustrated by the determination of NH4+ and of surfactants, it is shown that single stages or the entire sample preparation can be integrated by use of flow injection analysis. Problems of the matrix in determining NH4+ in, e.g., waste water, soil extracts or acid digests of food are discussed; the NH4+ can be separated from the matrix by gas diffusion from NaOH medium into a receptor stream for photometric detection. Surfactants can be separated from environmental, food or pharmaceutical samples by liquid - liquid ion-pair extraction into CHCl3, with use of a PTFE membrane as phase separator and photometric detection. Flow diagrams for these analyzes are presented.
Ammonium Surfactants Sample preparation Spectrophotometry Gas diffusion Online digestion Ion pair extraction Phase separator Teflon membrane Tecator

"Multivariate Sensor System For The Automatic Control Of Wastewater Streams"
Chem. Tech. 1994 Volume 46, Issue 1 Pages 77-86
Adler, B.;Brueckner, G.;Winterstein, M.

Abstract: Principles and operation of a sensor array for common water and wastewater analysis is described, together with fuzzy control of its operation such as pattern recognition for particular conditions of the water composition and the recognition of changes in the sensor performance. Field experiments were performed by a sensor array for conductivity, pH, and turbidity and a memory-programmable control for data acquisition. Stages of hard clustering by a main-component analysis (Henrion et al., 1986) and fuzzy clustering or alternatively, a neuronal network were used for data evaluation. The results indicated the successful recognition of 1% and 0.05% deviations of nonionic and anionic tensides, respectively. (SFS)
Conductivity pH Turbidity Electrochemical analysis Sensor Statistics Surfactant

"FIA Determination Of Lead With 4-(2-pyridylazo)resorcinol After Preconcentration On A Micro-column Of A Chelating Sorbent"
Collect. Czech. Chem. Commun. 1989 Volume 54, Issue 10 Pages 2674-2682
Kuban, V.;Bulawa, R.

Abstract: Sample solution (20 ml) was passed through a column (3 cm x 3 mm) of Spheron Oxin 1000, and Pb(II) was eluted with 0.1 M HCl or -HNO3 (0.3 mL min-1). The eluate passed into a stream of 0.2 mM 4-(2-pyridylazo)resorcinol (I) in 0.1 M borate buffer of pH 9.2 (0.3 mL min-1), and detection was at 518 nm. From 0.01 to 0.6 µM-Pb could be determined, with a coefficient of variation (n = 10) of 6.2% at 0.05 µM. Without pre-concentration, the method could be used to determine 1 to 20 µM- and 0.4 to 18 µM-Pb in normal and reversed (I solution injected into sample stream) modes, respectively (injection volume 50 µL). Selectivity was improved by masking with EDTA, tartaric acid and KCN. The method with pre-concentration. was applied to industrial waste water.
Lead Spectrophotometry Chelation Buffer Preconcentration Selectivity Interferences

"The Molybdate/ascorbic Acid Blue Method For The Phosphorus Determination In Very Dilute And Colored Extracts By Segmented-flow Analysis"
Commun. Soil Sci. Plant Anal. 1996 Volume 27, Issue 5-8 Pages 1363-1375
Coutinho, J.

Abstract: Soil was extracted by the method of Houba et al. (Ibid., 1990, 21, 2281) and the extract was injected into an FIA system for 100 s with air segmentation. The sample stream (1.6 ml/min) merged with a stream of 12 M HCl plus FFD6 wetting agent (0.1 ml/min), and the resulting stream passed through a five-turn mixing coil and then through a 20-turn mixing coil in a water bath at 50°C to a 70 cm dialyser for dialysis against an air-segmented stream of water containing 6 ml/l of FFD6 (0.8 ml/l). The dialysed stream then merged with streams of ammonium molybdate solution (0.1 ml/min) and ascorbic acid/antimony potassium tartrate solution (0.1 ml/min) and, after passage through a ten-turn mixing coil, the absorbance was measured at 880 nm. The calibration graph was linear for up to 400 µg/l of P with RSD (n = 10) of 0.6-5.6%. The detection limit was 2.8 µg/l of P. The method was also applied to waste water.
Phosphorus Spectrophotometry Dialysis

"Flow Injection Analysis Of Cyanide In Wastewater From Metal Plating Process"
Eisei Kagaku 1984 Volume 30, Issue 1 Pages 7-13
CHIYOMI OKUMOTO, MACHIKO NAGASHIMA, SHIGERU MIZOIRI, MASAYOSHI KAZAMA, KAZUYUKI AKIYAMA

Abstract: The sample (at 1.2 mL min-1) was mixed with aqueous 2% H2SO4 (0.4 mL min-1) to adjust the pH to <2 and the solution was mixed with a carrier flow of aqueous 10% NaCl (2.0 mL min-1). The liberated HCN diffused via a PTFE membrane in a gas diffusion cell at 40°C into a stream of 0.1 M NaOH (1.2 mL min-1), and this collector stream was monitored with a CN--selective electrode. By use of a calculated mean HCN permeability of 34% at 1 µg mL-1, a rectilinear calibration graph was obtained in the range 0.3 to 100 µg mL-1 of CN-. Forty samples could be analyzed in 1 h.
Cyanide Electrode Heated reaction Teflon membrane Process control Gas diffusion

"Method Comparison And Evaluation For The Analysis Of Weak Acid-dissociable Cyanide"
Environ. Sci. Technol. 1997 Volume 31, Issue 1 Pages 52-57
John R. Sebroski and Richard H. Ode

Abstract: This study compared and evaluated three methods to determine weak acid-dissociable cyanide. An emphasis was placed on data quality using a performance-based approach to overcome the problems associated with cyanide analyzes. The three methods compared were Standard Methods, 18th ed., Method 4500 CN- l (macro distillation, colorimetric finish); Bayer Method SA-61A (steam distillation at pH 4.5, ion selective electrode finish); and Bayer Method SA-100 (FlA or flow injection analysis, gas diffusion separation, and amperometric detection). The study demonstrated method detection limits, recoveries of cyanide species, and use of ligand exchange reagents to improve selected cyanide species recoveries. Potential interferences were examined with the FIA procedure to demonstrate that the method would be applicable to industrial wastewater samples subject to NPDES regulations. This performance-based approach led to a successful means to measure weak acid-dissociable cyanide in an industrial effluent where other approved methods have failed.
Cyanide Amperometry Electrode Gas diffusion Method comparison Standard method Interferences

"Determination Of Trace Silver With Catalytic Flow Injection Spectrophotometry"
Fenxi Ceshi Tongbao 1990 Volume 9, Issue 3 Pages 39-42
Yang Jiannan;Shi Naih;He Wanli

Abstract: A flow injection spectrophotometric method is described for the determination of trace Ag in wastewater based on the catalytic action of Ag(I) on the oxidation reaction of S2O82- in the presence of o-phenanthroline. Sample throughput is 70 h-1. The limit of detection is 5 ng mL-1 at room temperature Coefficients of variation were 5.78%.
Silver Catalysis Detection limit

"Determination Of Chromium(VI) In Industrial Waste Water By Flow Injection Analysis"
Fenxi Huaxue 1986 Volume 14, Issue 11 Pages 867-869
Yu, Z.;Li, X.

Abstract: A flow injection analysis method is described for determination of Cr(VI) with use of 1,5-diphenylcarbazide as color reagent. The system is capable of 103 determinations per hour and 100 µL of sample volume is required for each determination. The determination range and detection limit are up to 3 ppm and 0.03 ppm, respectively; the coefficient of variation is 0.6%.
Chromium(VI) Spectrophotometry

"Spectrophotometric Determination Of Cyanide In Waste Water In A Flow Injection Analysis System With Gas Diffusion Separation"
Fenxi Huaxue 1993 Volume 21, Issue 4 Pages 449-451
Ma, H.C.;Liu, J.F.

Abstract: A sample of waste water (1.2 mL min-1) was mixed with 0.3 M HCl (0.6 mL min-1) in a flow injection manifold before entering through a gas diffusion separation set-up alongside a stream of 0.01 M NaOH (0.4 mL min-1), reacting with 0.5 M phospate buffer of pH 6.5 and 0.6% chloramine-I (0.4 mL min-1) then with 2% pyridine - barbituric acid (0.8 mL min-1) in a reaction tube and detection at 494 nm. The calibration graph was rectilinear for 0.1 to 18 µg mL-1 of cyanide; the detection limit was 0.02 µg mL-1. The sampling rate was 65 h-1.
Cyanide Spectrophotometry Gas diffusion

"Flow Injection Spectrophotometric Determination Of P-phenylenediamine In Waste Water"
Fenxi Huaxue 1994 Volume 22, Issue 12 Pages 1285-1285
Chang, H.;Yang, J.N.

Abstract: Sample was adjusted to pH 7-8 and then 136 µL of the solution was injected and transferred by a carrier stream of 1% HCl at 1.4 ml/min to react with streams of 1% aniline and 4% K2S2O8 at 1 and 0.77 ml/min, respectively, in a reactor (96 cm x 0.77 mm i.d.) before measurement of absorbance at 660 nm. The calibration graph was linear for 1.6-12.8 µg/ml of p-phenylenediamine. Recoveries were 98.8-101%. Sampling frequency was 75 runs/h.
p-Phenylenediamine Spectrophotometry

"Spectrophotometric Determination Of Copper(II) And Cyanide Ions In Waste Water By Flow Injection Analysis"
Fenxi Huaxue 1995 Volume 23, Issue 1 Pages 36-38
Wang, P.;Jia, D.L.;Wang, Y.

Abstract: For the determination of Cu(II), 30-150 µL waste water was injected into a carrier stream of 2 M NH3/NH4Cl buffer of pH 8.2 containing 0.2% EDTA and 0.5% ammonium citrate at pH 8.2 which merged with a reagent stream of aqueous 0.2% sodium diethyldithiocarbamate and passed through a reactor (150 cm x 0.7 mm i.d.) before detection at 460 nm. When determining cyanide, the same set up at 35°C was used but the carrier stream was phosphate buffer of pH 7 containing 0.04% chloramine T and 1.25% isonicotinic acid/0.2% pyrazoline mixture was used as the color reagent stream. Detection limits for Cu and cyanide were 0.4 and 0.6 mg/l, respectively. The RSD were 0.6-0.8%. The method was employed in analysis of waste water from an electroplating factory, with recovery of 96-104%.
Copper(II) Cyanide Spectrophotometry Heated reaction Complexation

"Simultaneous Determination Of Chromium(III) And Chromium(VI) In Waste Water With Flow Injection Analysis Monitored By Chemiluminescence"
Fenxi Huaxue 1995 Volume 23, Issue 10 Pages 1148-1150
Zhang, H.S.;Yang, X.C.;Wu, L.P.

Abstract: A sample was adjusted to pH 3 and mixed with EDTA to a final concentration of 1 mM before dilution with water and injection in to a flow injection system. The carrier stream transported the sample to the shunt which divided the sample in two; the first portion was reacted directly with a mixture of 0.25 mM luminol and 20 mM H2O2 of pH 12 (2:1) for chemiluminescence measurement. The second portion was passed through a reduction column (2.5 cm x 2 mm i.d.) of Cu-coated Zn granules, then through a delay tubing (110 cm) prior to allowing the online generated Cr(III) and original Cr(III) to react with luminol/H2O2 and measuring the chemiluminescence. Calibration graphs were linear from 10 µM-1 nM. Detection limit was 23 nM-Cr(III). Using the standard-additions method, recoveries for Cr(III) and Cr(VI) were 95% and 97%, respectively; corresponding RSD were 0.37-4% and 1.2-4.4%. Sampling frequency was 60 runs per h. The method was applied to the analysis of waste water from a Cr-plating factory. Results were compared with those obtained by diphenylcarbazide photometry. The reduction column lasted >2200 runs.
Chromium(III) Chromium(VI) Chemiluminescence Speciation Simultaneous analysis Method comparison Reduction column Standard additions calibration

"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

"Reverse Flow Injection Chemiluminescence For Determination Of Trace Iron"
Fenxi Huaxue 1997 Volume 25, Issue 3 Pages 334-337
Zhou, Y.X.;Li, F.;Zhu, G.Y.;Sun, J.;Lei, J.

Abstract: A sample was injected into a stream (2.1 ml/min) of 0.1% NaHSO3 which merged with a reagent stream (2.1 ml/min) containing 0.25 mM o-phenanthroline, 0.6 mM luminol and 0.1 mM KIO4 and passed through a reaction tube (60 cm long) prior to measurement of chemiluminescence at an applied voltage of -674 V. The calibration graph was linear from 0.1 µg/l to 10 mg/l Fe and the detection limit was 3 ng/l Fe. For 5 µg/l Fe(II) the RSD (n = 9) was 0.9%. Recoveries were 97-102%. Only 10-fold Co(II) interfered. The method was used in the monitoring of total Fe in water treatment.
Iron Chemiluminescence Reverse Interferences

"Flow Injection Spectrophotometric Determination Of Microamounts Of Thiocyanate"
Fenxi Huaxue 1998 Volume 26, Issue 7 Pages 836-839
Wang, K.;Chen, X.G.;Huang, J.;Hu, Z.

Abstract: Two flow injection methods have been developed for the spectrophotometric determination of µamounts of thiocyanate, based on the reaction of 2-(3,5-dibromo-2-pyridylazo)-5-diethylamino-phenol(3,5-Br2-PADAP)-thiocyanate-dichromate system in acidic medium (method A), and the reaction of 3,5-Br2-PADAP-thiocyanate-Cerium(IV) system in acidic medium (method B). Both reactions produce unstable violet products with max. absorption at 602 nm. In system A, the calibration curve is linear in the range from 0.80 to 7.20 mg/L of SCN- and the detection limit is 0.27 mg/L. In system B, the calibration curve is linear in the range from 0.80 to 6.40 mg/L of SCN- and the detection limit is 0.30 mg/L. With a sample solution of 100 µL being injected, the sampling frequency is 60/h for A or B method. Both methods have been applied to determine thiocyanate in waste water and saliva of non-smokers and smokers with satisfactory results.
Thiocyanate ion Spectrophotometry

"Online Monitoring Of Chemical Oxygen Demand In Environmental Waste Water By Flow Injection Spectrophotometry"
Fenxi Kexue Xuebao 1996 Volume 12, Issue 2 Pages 18-21
Fan Shihua, Fang Zhaolun

Abstract: A flow injection system (diagram given) for the online measurement of COD of waste water is described. The sample was injected into a carrier stream of water (0.27 ml/min) and after filtering, the sample stream was mixed with a reagent stream of 0.3 µM-cerium(IV) sulfate solution containing 4% H2SO4 at 0.27 ml/min in a reaction coil (20 m x 0.5 mm i.d.) heated at 100°C. The absorbance was measured at 320 nm vs. a reagent blank. The calibration graph was linear up to 100 µg/ml and the RSD (n = 7) was ~2% for 60 µg/ml. Results were within±10% of those obtained by the batch dichromate method on synthetic COD reference samples.
Chemical oxygen demand Spectrophotometry Filtration Heated reaction Method comparison

"Determination Of Copper By Flow Injection Analysis Using The Ion Selective Electrode As Detector"
Fenxi Shiyanshi 1988 Volume 7, Issue 4 Pages 36-38
Yang Zihua, Sheng Shaqin and Zhao Guoliang

Abstract: Flow injection analysis was effected with a detection system incorporating two Cu(II)-selective electrodes as indicator and reference electrodes. The carrier stream contained 0.1 M KNO3 and 1 µM-Cu to ensure a steady baseline. For test analyzes of waste waters, results were compared with those obtained by spectrophotometry.
Copper Electrode Method comparison

"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

"Determination Of Silver In Waste Water By Dual-beam-spectrophotometric Flow Injection Analysis"
Fenxi Shiyanshi 1992 Volume 11, Issue 3 Pages 15-16
Zhao, Z.Y.;Ma, C.;Chen, H.;Sun, H.L.

Abstract: Sample was digested with HNO3 - H2SO4 and then diluted to a known volume A portion of the solution was carried with 0.25 M (NH4)2SO4 - NH4OH buffer of pH 9.5 (containing 0.05 M EDTA) at 4 mL min-1 to mix with a reagent stream (of 0.03 g of p-dimethylaminobenzalrhodanine, 3 g of gelatin, ethanolic concentrated ammonia and water to 250 mL) at 2.2 mL min-1 in a reaction coil (120 cm x 0.8 mm i.d.) followed by dual-beam spectrophotometry with measurement at 490 nm. Linearity range was from 0.01 to 23 mM Ag. The coefficient of variation (n = 7) was 0.8%. After pre-treatment and masking, interfering species were overcome. Results were satisfactory and compared with those obtained by AAS.
Silver Spectrophotometry Method comparison Interferences

"Continuous-flow Determination Of Total Organic Carbon In Water By Chemiluminescence Detection"
Fenxi Shiyanshi 1995 Volume 14, Issue 2 Pages 12-14
Liu, R.M.;Liu, D.J.;Zhang, Z.H.;Sun, A.L.;Liu, G.H.

Abstract: Sample was injected (3 ml/min) in a stream of 0.5 M H2SO4 (0.2 ml/min) and 6% K2S2O8 (1.5 ml/min) and mixed in a coil (800 cm x 1.2 mm i.d.) at 210°C. The mixture was cooled in a tube (100 cm x 1.2 mm i.d.), streams of 2 M H2SO4 (0.2 ml/min), 0.1 mM luminol/20 M-Co(II) in borate buffer of pH 9.2 (0.4 ml/min) and 0.05 M H2O2 (0.4 ml/min) were added and the intensity was measured by chemiluminescence. The calibration graph was linear from 0.1-12 g/ml of total organic carbon (TOC) and the detection limit was 0.04 g/ml. Common inorganic ions did not interfere but inorganic carbon compounds did and therefore acidification and removal of any O2 present by passing N2 gas through the solutions was required. Sampling frequency was 20 runs/h. The method was applied to the assay of TOC in lake water, river water and waste water, with recoveries of 90-104%.
Total organic carbon Chemiluminescence

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

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

"Simultaneous Determination Of Trace Amounts Of Mercury, Cadmium And Zinc By Ion Chromatography Using M-tetrakis(4-sulfophenyl)porphyrin [TPPS4] As Post-column Derivatization Agent"
Gaodeng Xuexiao Huaxue Xuebao 1990 Volume 11, Issue 2 Pages 136-139
Yan, D.;Zhang, J.;Schwedt, G.

Abstract: The cited determination was carried out with use of TPPS4 as derivatization agent, 4-(2-pyridylazo)resorcinol in Na2B4O7 - NaOH buffer (pH 10.3 to 12) containing NaCl as the derivatization catalyst and tartaric acid - NaCl as mobile phase. A chemically bonded silica gel cation-exchanger was used as the stationary phase and the separation was completed in 10 min. The method was applied to the analysis of waste water, silicate and corn samples.
Mercury Cadmium Zinc HPIC Post-column derivatization Buffer pH Catalysis

"Flow Injection Analysis For The Determination Of Total Nitrogen And Total Phosphorus In Animal Wastewater"
Gesuido Kyokaishi 1988 Volume 25, Issue 286 Pages 74-80
Haga, Kiyonori; Osada, Takashi; Harada, Yasuo (SFS)

Abstract: PO43- and NO3- in animal rearing wastewater are determined by flow-injection anal. using molybdene blue spectrophotometry or UV spectrometry, after digestion of the wastes by the method of M. Hosomi (1983). The injection rate is 1/min. Correlation coefficients between this method and the conventional methods are 0.9976 and 0.9996 for N and P, respectively. (SFS)
Nitrogen, total Phosphorus Spectrophotometry Sample preparation Merging zones Method comparison

"Rapid Automated Determination Of COD- A New Process Analysis System For Waste Water"
GIT Fachz. Lab. 1992 Volume 36, Issue 1 Pages 33-NA
Weuster Botz, D.;Wandrey, C.

Abstract: Waste water (10 µL) is degassed and injected into a carrier stream of HgSO4 solution in concentrated H2SO4, followed by mixing with a stream of K2Cr2O7 in concentrated H2SO4 and heating in a reactor coil at 50 to 210°C. The unconsumed K2Cr2O7 is measured spectrophotometrically at 460 nm. The method is applicable for 20 to 35,000 g L-1 of O and each sample can be analyzed in 3 to 7 min, with coefficient of variation of 1 to 5% (for benzoic and phthalic acids as model substances).
Chemical oxygen demand Spectrophotometry Heated reaction

"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

"Study On Application Of Flow Injection Analysis With An Amperometric Detector - Determination Of Silver Ion In Wastewaters By Flow Injection Analysis"
Huanjing Huaxue 1982 Volume 1, Issue 6 Pages 422-428
Ma, Huichang; Yan, Huiyu

Abstract: Silver in wastewater is determined by the flow injection analysis at a concentration >5 ppb with a relative standard deviation of ≤3%. A linear relation exists between the response current peak height and silver concentration 5 ppb-5 ppm. The recovery rate for added Ag 1.45 µg/50 mL is 98-100%.
Silver Amperometry Theory

"Study On The Determination Of Arsenic In Wastewater By Using Single Valve FIA Combined With Hydride Generation Spectrophotometry"
Huanjing Kexue 1994 Volume 15, Issue 5 Pages 71-72
Liu Guoquan, Wang Chunxu, He Yuaping

Abstract: A single valve FIA (Flow Injection Analysis) system with hydride generation spectrophotometric detection was designed for the determination of the trace arsenic in wastewater. This FIA system had no need for any carrying gas. The new hydride generator and the absorbing device made by the authors were used in the FIA system. The KBH-4 solution and the mixed silver nitrate-polyvinyl alcohol-ethanol solution were used for the generation and absorption, respectively, of arsenic hydride. The experimental results show that this method was very good for the determination of trace arsenic in wastewater. The FIA system had main advantages, including simple equipment, easy operation, high sensitivity, rapid determination (30 samples/h), good reproducibility (RSD = 3.04%) and low detection limit (1.82 x 10^-9 g/ml).
Arsenic Spectrophotometry Valve Phase separator Sensitivity

"Online Reverse Flow Injection Analysis For Continuous Monitoring Of Electroplating Wastewater"
Huanjing Wuran Yu Fangzhi 1990 Volume 12, Issue 2 Pages 43-46
Zhou Zhifa, Shi Jiliang, Ye Shuaiguan

Abstract: A simple and rapid reversed flow injection - AAS method for determining Cr(VI), Ni(II) and Cu(II) in electroplating waste water is described.
Chromium(VI) Nickel(II) Copper(II) Spectrophotometry Reverse

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

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

"Automated Measuring System For Biological Wastewater Treatment Plant With Biological Removal Of Phosphate"
IFAC Proc. Ser. 1986 Volume 4, Issue 1 Pages 131-136
Pedersen, K. M.; Haagensen, P.; Kuemmel, M.; Soeeberg, H. (SFS)

Abstract: An automated method for the monitoring of concentrations of PO43-, NO3-, and NH4+ in effluents from biological wastewater treatment plants is based on flow injection with sampling by dialysis. (SFS)
Phosphate Nitrate Ammonia Automation Dialysis

"Similar But Not Equal"
Ind. Wastewater 1998 Volume 6, Issue 6 Pages 41-44
MacFarlane, I.D.;Logan, C.M.;Elseroad, H.J.

Abstract: Although wastewater discharges of CN- have been regulated for many years, lack of accurate methods to quantify different forms of CN- requires dischargers of wastewater which contains less toxic or non-toxic forms of CN- to use overly aggressive, expensive treatment methods or take site-specific, risk-based approaches to revise CN- criteria. The CNA method (CN- amenable to chlorination) is the most accurate USEPA-approve method to measure compliance with free CN- standards or limits; however, USEPA has proposed approving other methods to measure available CN- at lower concentrations and with better precision (flow injection and ligand-exchange methods). Since methods to measure compliance do not differentiate between free, weakly complexed, or strongly complexed CN-, selecting cost-effective treatment methods for metal-complexed CN- is difficult. Although wastewater may contain only strongly complexed forms of CN-, which are less toxic than free CN-, dischargers must treat wastewater with the assumption that any CN- detected is of the most bioavailable, toxic form. New, revised CN- anal. methods being developed by USEPA and the ASTM are encouraging. A USEPA-approved method to measure free CN- in wastewater, receiving water, or groundwater would improve efforts to characterize samples and facilitate accurate input to fate and transport assessments.
Cyanide Review Standard method

"Spectrophotometric Flow Injection Determination Of Thiocyanate"
Indian J. Chem. A 1997 Volume 36, Issue 4 Pages 344-346
ENSAFI A.A.

Abstract: The determination was performed using a previously described flow injection system (Ensafi, Ibid., 1997, 36, 105). The following optimum conditions were used: 0.4 M sodium azide; 0.175 mM iodine solution (prepared by dissolving I2 in KI solution); and a pH of 5. Sodium azide solution, phosphate buffer, iodine solution and water were pumped at a flow rate of 30 ml/h. A portion (300 µL) of thiocyanate solution was injected and the absorbance was read at 349 nm after reaction in a 300 cm mixing coil at 25°C. The calibration graph was linear from 0.005-1.8 µg/ml and the limit of detection was 0.62 ng/ml. The RSD (n = 10) was 1.3% and the sample throughput was ~40/h. The method was applied to the determination of thiocyanate in waste water and urine. An interference study is described.
Thiocyanate ion Spectrophotometry Detection limit Interferences Optimization

"Electrochemical Analysis Of Sulfur Compounds Of Environmental Interest"
Int. J. Environ. Anal. Chem. 1985 Volume 20, Issue 3-4 Pages 167-177
Thomas, J.D.R.

Abstract: A review is presented, largely of work carried out at UWIST, with emphasis on the use of S2--selective electrodes for monitoring industrial liquors (e.g., black liquor) and effluents and sewage effluents and for monitoring the growth of S2--producing bacteria, of importance in the context of industrial spoilage, and also on flow injection analysis with use of ion-selective electrodes and on means of overcoming interference by H2O2. (30 references).
Sulfide Electrode Interferences Review

"Evaluation Of Combined Flow Injection High Performance Liquid Chromatography For The Determination Of Three Organophosphorus Pesticides In Liquid Wastes"
Int. J. Environ. Anal. Chem. 1987 Volume 30, Issue 1-2 Pages 59-68
Farran, A.;De Pablo, J.

Abstract: In development of the method, solution containing azinphos-methyl, diazinon and fenthion were analyzed by HPLC with introduction by continuous or normal flow injection analysis. The HPLC was carried out on a column (12 cm x 4 mm) of Nucleosil-C18 with aqueous 60% acetonitrile as mobile phase (1 mL min-1) and detection at 220 nm. The limit of detection was 0.5 mg l-1. Removal of pesticides from liquid waste by adsorption on active carbon was also studied.
azinphos-methyl Diazinon Fenthion Pesticides HPLC Spectrophotometry Activated carbon

"Determination Of Nitrite By Reverse Flow Injection Analysis"
Int. J. Environ. Anal. Chem. 1988 Volume 32, Issue 3-4 Pages 279-289
Vinas, P.;Hernandez Cordoba, M.;Sanchez Pedreno, C.

Abstract: In a single-channel manifold (diagram given) a 135 µL portion of 0.5 mM Safranine T (C. I. Basic Red 2) in 1.5 M HCl was injected into the carrier stream of 0.01 M NaNO2 (3.5 mL min-1). The two solution were mixed in a reaction coil (8 m x 0.5 mm i.d.), and the absorbance of the diazo dye formed was measured at 345 nm. The calibration graph was rectilinear between 0.05 and 4 µg mL-1 of NO2-. In the determination of 0.2 and 2 µg mL-1 of NO2-, the coefficient of variation (n = 10) were 2.2 and 1.5%, respectively. The method was applied in the determination of NO2- in waste water and meat.
Nitrite Spectrophotometry Reverse

"Enzymatic Determination Of Dimethylformamide In Wastewater Using Flow Injection Analysis"
Int. J. Environ. Anal. Chem. 1988 Volume 33, Issue 2 Pages 131-139
Ludi, H.;Garn, M.;Ghisalba, O.;Schar, H.

Abstract: Waste water was diluted with 67 mM phosphate buffer of pH 7.0, and the solution (0.1 ml) was injected into the carrier stream (0.32 mL min-1) of 67 mM phosphate buffer (pH 7.0) and passed through an enzyme reactor containing immobilized NN-dimethylformamidase (cf. Schaer et al., Eur. J. Biochem., 1986, 158, 469). The DMF produced catalyzed the polymerization of 1,4-benzoquinone in another stream of the flow injection system, and detection of the polymer was at 500 nm. The calibration graph covered the range up to 15 mM DMF; the detection limit was 0.05 mM. Results generally agreed well with those obtained by GC.
Dimethylformamide Spectrophotometry Gas diffusion Immobilized enzyme Reverse

"Determination Of Trivalent And Hexavalent Chromium In Waste-water By Flow Injection Chemiluminescence Analysis"
Int. J. Environ. Anal. Chem. 1995 Volume 61, Issue 3 Pages 169-175
R. Escobar; Q. Lin; A. Guira&uacute;m; F. F. De La Rosa

Abstract: Flow injection analysis has been applied to the determination of both Cr(III) and Cr(VI) in waste water. The method is based on the measurement of Cr(III)-catalyzed light emission from luminol oxidation by hydrogen peroxide and the apparatus consists of a FIA system with a flow cell suitable for chemiluminescence detection. Cr(III) is determined directly by the chemiluminescence, meanwhile Cr(VI) is reduced previously to Cr(III) by H2O2 in acidic medium and then the total amount of chromium is determined. The concentration of Cr(VI) is obtained by the difference between the Cr(III) and Cr(VI) determinations. We have analyzed synthetic mixtures of both species, Cr(VI) and Cr(III), using this method and its application to waste water has been shown to be very efficient. The method is simple, inexpensive, sensitive (subnanomolar concentrations), selective and rapid. Tens of samples per hour can be performed with tolerance to potential interferants. (39 References) Cr(III) was determined directly by chemiluminescence: Cr(VI) was reduced to Cr(III) by addition of 0.5 mL 0.2 M HCl and 0.2 mL 30% H2O2, followed by heating at 80°C for 30 min. The Cr(VI) was then determined from the difference between total Cr content and Cr(III). Reagent streams in the FIA apparatus (schematic given) were sample, water as carrier, reagent streams of 1 mM luminol (flow rate 2.5 ml/min) and 0.14 mM H2O2( flow rate 2.1 ml/min). The calibration graph was linear from 0.01-6 ng/ml Cr(III). The method was simple, inexpensive, had high sensitivity and was tolerant of interfering species. Recoveries were in the range 94-110%, an RSD (n = 12) of 6% for 25 ng/ml of Cr(III) and Cr(VI). Several tens of samples could be analyzed per hour.
Chromium(III) Chromium(VI) Chemiluminescence Interferences Preconcentration Speciation

"FIA Tubular Potentiometric Detectors Based On Homogeneous Crystalline Membranes - Their Use In The Determination Of Chloride And Sulfide Ions In Water"
Int. J. Environ. Anal. Chem. 1990 Volume 38, Issue 2 Pages 127-133
Jos&eacute; L. F. C. Lima; L&iacute;vio S. M. Rocha

Abstract: Tubular detectors were constructed by welding a silver plate (2 mm x 4 mm) to a shielded electrical cable, then attaching a membrane containing AgS or AgCl to the plate using a Ag-based conductive epoxy-glue. The detector was cast in non-conductive epoxy and holes were made to receive the PVC connectors of the FIA manifold. The detection limits for Cl- and S2- were 50 and 10 µM, respectively, in standard solution; durability of the detectors was >1 year. Similar detectors can be made for Br-, I-, Cd, Cu2+ and Pb2+. Results for natural and waste water agreed with those by conventional ion-selective electrode procedures. The advantages of FIA are discussed.
Chloride Sulfide Potentiometry Electrode Electrode Membrane Detector Method comparison

"Automated Determination Of Inorganic Ions In Environmental Samples"
Int. Lab. 1989 Volume 19, Issue 7 Pages 64-66
Ranger, C.B.

Abstract: A description is given of the hardware and software of the QuikChem AE computer-controlled automatic analyzer. (Lachat Instruments). The system (which is intended for analysis of potable and waste water) incorporates robotic sampling and automated dilution facilities, and can accommodate up to seven parallel analytical channels for the determination of cations or anions by flow injection or ion-chromatographic procedures. A micro-distillation unit is also available for the determination of phenols and CN-.
Computer Lachat Robot

"Alternative Catalyst To Mercury For Kjeldahl Determination Of Nitrogen In Water And Waste-water Samples"
J. AOAC Int. 1995 Volume 78, Issue 6 Pages 1516-1519
Kim A. Anderson and Gregory M&ouml;ller

Abstract: A non-polluting alternative catalyst was used in a U.S. Environmental Protection Agency (EPA) Kjeldahl digestion procedure for water and wastewater samples. The colorimetric semiautomated block digestion method (EPA Method 351.2) was essentially unchanged except that 1 mL of a saturated solution of titanium dioxide was added to the digestant mixture, instead of 2 g mercuric oxide. Titanium dioxide is a nontoxic compound, which makes an excellent replacement in total Kjeldahl nitrogen (TKN) determination. Samples were digested and then placed on a flow injection autoanalyzer for ammonia determination. All other digestion and analysis procedures were the same as in the original method. Detection limit for TKN was 0.1 mg/L. Recovery of glutamic acid averaged 96.2%. Recoveries of standard reference water samples over a 9 month period averaged >95%. (14 References)
Nitrogen, kjeldahl Spectrophotometry Sample preparation Reference material Standard method Kjeldahl

"Microcomputers In A Water Authority Laboratory"
J. Autom. Methods Manag. Chem. 1985 Volume 7, Issue 4 Pages 192-196
M. P. BERTENSHAW and K. C. WHEATSTONE

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

"Novel Approach To Non-segmented Flow Analysis. 2. A Prototype High Performance Analyser"
J. Autom. Methods Manag. Chem. 1988 Volume 10, Issue 1 Pages 25-30
D. J. MALCOLME-LAWES and C. PASQUINI

Abstract: The instrument is based on a gas-pressure-driven carrier stream and reagent solution controlled by computer-switched solenoid valves (details of operation given). The performance is assessed by the determination of Cr(VI), based on its reaction with acidified diphenylcarbazide(I). The reagent solution are 0.06% I in 5% acetone and aqueous 0.8 M H2SO4, and the carrier is aqueous 0.4 M H2SO4 containing 2.5% of acetone. Absorbance was measured at 545 nm. The calibration graph was rectilinear for 0.5 to 3 ppm, and the detection limit was 10 ppb. The system was also applied in the determination of NH4+ in potable and waste water, by using the Berthelot reaction catalyzed by sodium nitroprusside. The calibration graph was rectilinear from 0.3 to 1.5 ppm. The detection limit was 7 ppb. Results are similar to those obtained by a segmented flow method.
Ammonium Chromium(VI) Spectrophotometry Computer Review

"Automated Continuous Monitoring Of Inorganic And Total Mercury In Waste Water And Other Waters By Flow Injection Analysis And Cold Vapor Atomic Absorption Spectrometry"
J. Autom. Methods Manag. Chem. 1988 Volume 10, Issue 3 Pages 140-143
S. E. BIRNIE

Abstract: The sample stream and carrier reagent (aqueous 1% HNO3) were pumped in the flow injection system (illustrated) at 1.0 and 2.9 mL min-1, respectively, and after sample injection the stream was mixed with 50% H2SO4 and then water (each 0.6 mL min-1). In the reaction coil the stream was mixed with a 10% solution of SnCl2 in 10% HCl (0.8 mL min-1), and the stream passed into a second reaction coil where Hg(II) was reduced to Hg0. The Hg was volatilized by aeration in an air - liquid separator and the vapor was passed through a condenser to a silica flow cell, where the absorbance was measured continuously for each sample injection at 253.7 nm for determination of inorganic Hg. The determination of total Hg differed in that the stream was mixed with aqueous 4% K2S2O8 instead of water, and the first reaction coil was heated at 65°C for conversion of organic into inorganic Hg. Calibration graphs were rectilinear up to 10 µg mL-1 of Hg and the detection limit was 0.02 µg mL-1. The coefficient of variation (n = 30) at 6 µg mL-1 was 0.9%. Sulfide, Cl-, Se, Cu, Pd, Pt, Au and Ag interfere; ClO- can be removed before injection by boiling the sample with KBr.
Methylmercury ion Mercury(II) Spectrophotometry Heated reaction Interferences Phase separator Speciation

"Studies On Precision For Silicate Determination By Flow Injection Analysis And Correlation Between The Flow Injection Method And Conventional Method"
J. Flow Injection Anal. 1989 Volume 6, Issue 2 Pages 151-159
Toshihiko Miyaji, and Kiyokatsu Kibi

Abstract: Two flow injection analysis methods are described. For method (i), sample (100 µL) is injected into a carrier stream (1 mL min-1) of water and mixed with a reagent stream (1 mL min-1) of 1% (NH4)2MoO4 in 0.25 M HCl at 60°C in a 3-m coil followed by a stream of 2% oxalic acid (0.5 mL min-1) and detection at 400 nm. For method (ii), an additional reagent stream containing 0.05% 1-amino-2-naphthol-4-sulfonic acid, 0.2% Na2SO4 and 2% NaHSO3 (0.5 mL min-1) was added to the mixture used in method (i) just before detection at 815 nm. After addition of 2% oxalic acid, P and As at 50 ppm, 1 ppm of Fe(III) and 2% of NaCl did not interfere. Detection limits for (i) and (ii) were 0.03 and 0.0023 mg L-1 of Si, respectively; for the determination of 10 ppm of Si by method (i) and 1 ppm of Si by method (ii), the corresponding coefficient of variation (n = 10) were 0.45 and 0.59%. Sample throughput was 60 h-1. Results obtained by methods (i) and (ii) correlated well with each other and the Japanese Industrial Standard method. The methods were applied in the analysis of tap water, well water and industrial waste water.
Silicate Spectrophotometry Precision Method comparison Standard method Interferences

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

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

"Radiometric Detection In Flow Injection Analysis (radiometric Flow Injection Analysis)"
J. Radioanal. Nucl. Chem. 1994 Volume 187, Issue 2 Pages 117-122
Myint U, Ba Han, Khin Mg Myoe, Aung Kywe, Thida and J. T&ouml;lgyessy

Abstract: The simple single-line manifold described consists of a constant-head gravity feed for carrier water, an injection port [cf. Betteridge et al., Analyst (London), 1978, 103, 897], a mixing coil (coiled plastic tubing), a flow cell [coiled plastic tubing (70-180 cm) on a cardboard backing] and a NaI(Tl) detector with a single-channel analyzer.. The system has been used to determine 60Co
Cobalt-60 Radiochemical Optimization

"Modified And Reverse Radiometric Flow Injection Analysis"
J. Radioanal. Nucl. Chem. 1994 Volume 187, Issue 3 Pages 179-184
Myint U, Ba Han, Khin Mg Myoe, Aung Kywe, Thida and J. T&ouml;lgyessy

Abstract: The radiometric flow injection analyzer. previously described (cf., Ibid., 1994, 187, 117) was modified slightly by using gravity feed of the sample from a burette, with separate control of the liquid height in the burette and the carrier reservoir. The method was tested with use of 137Cs or 60Co solution, with counting of the activity in 10 s periods. Calibration graphs of amount injected against peak height (or peak depth for reverse flow injection) were linear, implying similar peak shapes and dispersions. Solutions containing both radionuclides were also analyzed with use of a NaI(Tl) multichannel analyzer.. The reverse flow injection method seems well suited to the analysis of radioactive waste waters.
Cesium-137 Cobalt-60 Radiochemical Peak shape Reverse

"Reverse Radiometric Flow Injection Analysis (RFIA) Of Radioactive Waste Waters With An ASIA (Ismatec) Analyser"
J. Radioanal. Nucl. Chem. 1994 Volume 187, Issue 5 Pages 351-354
Myint U, J. T&ouml;lgyessy, Naing Win, Khaing San, Ba Han and Khin Mg Myoe

Abstract: A FIA method for the determination of 131I in waste water was described in which the analyte solution was used as the carrier stream. A 0.1-0.83 mL volume of water was injected into the waste water stream (1.25 ml/min) and passed through the flow detector cell. The detector cell consisted of a coiled plastic tube (60 cm length) placed adjacent to a NaI(Tl) scintillation counter. A linear relationship between peak height and volume of water injected was obtained. No other details are given.
Iodine 131 Radiochemical Scintillation counter Detector Flowcell

"Radiometric Flow Injection Analysis With An ASIA (Ismatec) Analyser"
J. Radioanal. Nucl. Chem. 1994 Volume 187, Issue 5 Pages 345-349
Myint U, J. T&ouml;lgyessy, Naing Win, Khaing San, Ba Han and Khin Mg Myoe

Abstract: A FIA system for the determination of 131I was described. A 0.1-0.88 mL volume of analyte solution was injected into a water carrier stream (1.25 ml/min) and passed through the flow detector cell. The detector cell consisted of a coiled plastic tube (60 cm length) placed adjacent to a NaI(Tl) scintillation detector. A linear relationship between peak height and injected volume was obtained. No other details are given.
Iodine 131 Radiochemical Scintillation counter Flowcell Detector

"Simultaneous Determination Of Cobalt-60, Iodine-131 And Caesium-137 In Model Radioactive Waste Water By Reverse Radiometric Flow Injection Analysis With The Aid Of A Multichannel Analyser"
J. Radioanal. Nucl. Chem. 1995 Volume 201, Issue 2 Pages 171-176
Myint U, Than Than Soe, Khaing San, Ba Han, Thida, Khin Mg Myoe and J. T&ouml;lgyessy

Abstract: H2O (0.3, 0.6, 1.2 or 1.5 ml) was injected into a stream of the sample (1 ml/min) in the radiochemical FIA system described previously (Ibid., 1994, 187, 351), which incorporated a NaI(Tl) detector connected to a multichannel analyzer.. The depths of the reverse FIA peaks for the different volumes of water injected are shown diagrammatically and graphically for 131I, 137Cs and 60Co. Clearly separated peaks for these radioisotopes in a single sample stream upon injection of water are shown, the peak depth for a particular radioisotope being referred to a calibration graph for that radioisotope with the same injection volume of H2O.
Cesium-137 Cobalt-60 Iodine 131 Radiochemical Scintillation counter Spectroscopy Reverse

"Flow Injection System For Monitoring Of Total Nitrogen And Control Of Eutrophication In An Aquatic Environment"
Eisei Kagaku 1994 Volume 40, Issue 2 Pages 122-131
TAKASHI KORENAGA, XIAOJING ZHOU, TOSIO MORIWAKE, SUMIO SHINODA

Abstract: Sample (200 µL) was injected to a carrier stream of water before oxidation in a reaction tube (5 m x 1 mm i.d.) at 120°C with a stream of oxidant solution comprising potassium peroxydisulfate in 1N-NaOH (30 mg/ml); reduction in a tube (5 m x 1 mm i.d.) at 60°C with a stream of reducing agent solution prepared from 0.7 g of hydrazine sulfate, 2 mg of CuSO4, and 20 mg of ZnSO4 in 1 l of H2O; reaction of the total nitrite with a stream of color reagent solution containing N-(1-naphthyl)ethylenediammonium dichloride and sulfanilamide in 30% HCl in a coloration tube (3 m x 1 mm i.d.); and detection at 540 nm; all streams were at flow-rate of 0.3 ml/min. The calibration range was 0.002-10 mg/l of nitrogen. The RSD (n = 12) was 1.2%. Sampling frequency was 20 samples/h. The method was applied to tap water and waste water from water treatment plants and laboratories. Little interference was observed. For continuous automated field monitoring, water sample was transported at 4-6 l/min to the constant head device before treatment and analysis.
Nitrogen Interferences

"Determination Of Trace Amounts Of Selenium In Environmental Samples By Hydride-generation Atomic Absorption Spectrometry Combined With The Flow Injection Analysis Technique"
Kexue Tongbao 1986 Volume 31, Issue 11 Pages 791-792
WANG XIU, FANG ZHAOLUN

Abstract: The methodology and apparatus for a hydride-generation AAS - flow injection analysis system is described. The system is used for the determination of Se in soil, plants or waste waters. An aliquot of the homogenized sample was injected into 2 M HCl as carrier solution (12 mL min-1) and mixed in the mixing coil. The Se was reduced with NaBH4 at 2 mL min-1 in the reaction coil and the H2Se and H were mixed with Ar as carrier gas (150 mL min-1) and swept into a gas - liquid separator for H2Se to be determined by AAS at 700°C. The detection limit for Se was 0.07 ng mL-1 and the coefficient of variation was <2%.
Selenium Spectrophotometry Phase separator

"Flow Injection Analysis Of Cyanide In Waste Water With Gas Diffusion Separation"
Kexue Tongbao 1986 Volume 31, Issue 24 Pages 1728-1728
ZHU ZHAOHAI, FANG ZHAOLUN

Abstract: An automated flow injection analysis system is described for the determination of CN-, which is separated from acidified waste water samples at 60°C by online gas diffusion through a PTFE membrane into 0.025 M NaOH as acceptor solution. The sample loop was used for pre-concentration of CN- before analysis by the isonicotinic acid - pyrazolone colorimetric method. The detection limit of CN- was 6 µg L-1 and the coefficient of variation was 1.4% (n = 22) for 0.5 mg L-1 of CN-. Recoveries were 92 to 105%.
Cyanide Spectrophotometry Gas diffusion Heated reaction Preconcentration Teflon membrane

"Rapid Differential Determination Of Phosphate And Total Phosphorus In Waste Water By Flow Injection Inductively Coupled Plasma Emission Spectrometry"
Kogai 1989 Volume 24, Issue 2 Pages 87-93
Miyazaki, A.;Bansho, K.

Abstract: The cited system was used for the determination of PO43- by the molybdovanadophosphoric acid method and total P by ICP-AES. For the latter a cyclone spray chamber performed best and measurement at 213.618 nm decreased interference from Mo and V. Detection limits were 5 and 0.6 ppm, respectively. Sampling rate was 40 per h.
Phosphorus Phosphate Spectrophotometry Nebulizer Interferences

"Faster Microwave Digestion By Flow Injection"
Lab. Equip. Dig. 1992 Volume 30, Issue 10 Pages 13-15
Lofty, D.

Abstract: An automated online microwave digester for sample preparation in flow injection analysis (schematic diagram given) is described. Slurries of analyte in dilute acid (e.g., 5% HNO3) are subjected to microwave irradiation in a sealed vessel to bring about dissolution; such sample preparation for AAS, ICP or ICP - MS, is fast (~ 2 to 3 min) and continuous. The technique was applied in the determination of selected metals in biological materials and the colorimetric determination of phosphate in waste water, recoveries are tabulated.
Metals Phosphate Sample preparation Mass spectrometry Spectrophotometry Spectrophotometry Microwave Online digestion Slurry

"Determination Of Orthophosphates By Sequential Injection Analysis"
Lab. Rob. Autom. 1995 Volume 7, Issue 5 Pages 245-255
Crespi, A.;Forteza, R.;Cerda, V.

Abstract: The cited method was based on the formation of molybdophosphate. A schematic diagram of the manifold is given. A six-way valve selected the appropriate line whilst a burette aspirated or propelled preset volumes of carrier, reagent and sample. water was used as the propellant. The system involved: (i) aspiration of the carrier volume; (ii) aspiration of the sample volume; (iii) aspiration of the reagent volume; and (iv) injection of the overall aspirated volume to the detector. The carrier and reagent used was 3 g/L of molybdate in 0.6% H2SO4; the orthophosphate concentration was 0.2 mM. Sample volumes of 50, 100, 200, 350 and 500 µL were used. The optimal detection potential was 220 mV vs. Ag/AgCl. The calibration graph was linear from 2.5-25 ppm orthophosphate. The method was applied to water and waste water.
Phosphate Electrochemical analysis Potentiometry Sequential injection Optimization

"Simultaneous Determination Of Chloride And PH In Waste Waters By Sequential Injection Analysis"
Lab. Rob. Autom. 1996 Volume 8, Issue 3 Pages 165-170
J. Alpizar, A. Crespi, A. Cladera, R. Forteza, V. Cerd&aacute;

Abstract: An online sequential injection analysis procedure with potentiometric detection was developed for the simultaneous determination of chloride and pH in waste water. A diagram of the experimental set-up is given. The pH was measured by stopping the flow and propelling 3 mL to a separate pH flow cell where the pH was measured with a combined glass electrode during the chloride determination. For chloride determination, the ionic strength was adjusted with an ionic strength adjuster buffer before detection. The results were similar to those achieved by a batch-potentiometric method. RSD (n = 20) were 1 and 1.2% for chloride and pH measurements, respectively, with use of 50 ppm chloride and pH 4 buffer solutions.
Chloride pH Potentiometry Electrode Sequential injection Buffer Ionic strength Method comparison Stopped-flow

"Continuous-flow. Continuous Determination Of Ammonium In Water And Waste Water"
LaborPraxis 1988 Volume 12, Issue 5 Pages 542-547
Braumann, T.

Abstract: The method is based on the diffusion of NH3 through a selective gas-permeable membrane and collection for differential conductometric detection of NH4+ in H3BO3 solution Use of the GAT N-360 continuous-flow apparatus (illustrated diagrammatically) permits determination of NH3 over a range of 20 to 1000 ppb and analysis of 60 samples h-1 with no significant interference. The method is easily automated. Introduction of a reduction cartridge permits determination of NO3- and NO2- as well as NH3.
Ammonium Nitrate Nitrite Electrode Automation Gas diffusion Interferences Reduction column

"Flow Injection Analysis System With Ion-selective Electrodes"
LaborPraxis 1990 Volume 14, Issue 7-8 Pages 596-597
Schwedt, G.

Abstract: The performance of such an analyzer. is demonstrated by the determination of S2- and CN- in waste water, for which the respective limits of determination are 0.03 and 0.1 mg l-1.
Electrode Detection limit

"Determination Of Micro-amounts Of Copper In Waste Water By Flow Injection Analysis Using The Checking Effect Of The Chemiluminescence Reaction"
Lihua Jianyan, Huaxue Fence 1993 Volume 29, Issue 5 Pages 290-291
Li, G.H.;Zhang, W.G.;Meng, Z.

Abstract: An FIA system was developed for the determination of Cu based on the inhibition of the chemiluminescence reaction of luminol with KMnO4 by Cu2+ (cf. Anal. Abstr. 1991, 53, 12H62). For determining Cu in waste water, a sample was filtered, the filtrate was adjusted to pH 5 and passed through a column of sulfhydrylated cotton. The adsorbed Cu2+ was eluted with 0.1 M HNO3 and the eluate was diluted for the determination of Cu2+ by the cited method. Calibration graphs were linear from 0.01-1 µg/ml of Cu2+ and the detection limit was 8.5 ng/ml; the RSD was 1.8%. Interfering elements were investigated.
Copper Chemiluminescence Interferences

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

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

"Determination Of Alkaline Phosphatase-hydrolyzable Phosphorus In Natural Water Systems By Enzymatic Flow Injection"
Limnol. Oceanogr. 1994 Volume 39, Issue 8 Pages 1993-2000
SHAN, YING, IAN D. MCKELVIE, AND BARRY T. HART

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

"Instrumental Analytical Method For The Determination Of Traces Of Lead By Atomic Absorption Measurements In A Flow System"
Magy. Kem. Foly. 1996 Volume 102, Issue 12 Pages 542-545
Papp, L.

Abstract: A hydride-generation system for the determination of Pb in air (passed through HNO3) and water by quartz-cell AAS is described and illustrated. Flow injection manifolds incorporating the system are also shown. The detection limit in a 0.2 mL injection is 17 ng.
Lead Spectrophotometry

"Semiautomated Determination Of COD In Wastewater Samples"
Mem. Sch. Eng. Okayama Univ. 1980 Volume 14, Issue 2 Pages 119-129
Korenaga Takashi;Ikatsu Hisayoshi;Ikatsu Hisayoshi;Moriwake Toshio;Takahashi Teruo

Abstract: A new method based on the principle of flow injection analysis is presented for the semiautomated determination of chemical oxygen demand (COD) in environmental water samples. The method is rapid and continuous, and suitable for the monitoring of COD in wastewaters. The apparatus used was simply constructed by parts commercially available for high performance liquid chromatography. Teflon tubing heated with a boiling watAr was used as a reactor and simultaneously used for mixing coils and transmission lines. The operating conditions were examined to apply the determination of COD in wastewaters by using glucose as a standard COD substance. The procedures recommended are as follows: Both 4.9 x l0-4 M potassium permanganate and 6. 7 % sulfuric acid solutions are individually pumped, 20 pL of a sample solution is injected into the flow of the sulfuric acid solution, and then mixed with a mixing joint. The mixed solution is transported to a flow cell situated in a spectrophotometer fixed at a wavelength of 525 nm, and decrements of absorbance are recorded. The peaks were reproducibly obtained at a concentration-range of 10^-200 mg-COD 1 L-1. Chloride up to 1000 mg L-1 was not interfered at all. Various wastewater samples were analyzed by the proposed method at a sampling rate of 30 samples .per hour, and the apparent COD values obtained were compared with the manual COD ones obtained by JIS method.
Chemical oxygen demand Spectrophotometry Interferences Method comparison Standard method

"Effect Of Silver Salt On The Determination Of Chemical Oxygen Demand By Flow Injection Analysis"
Nippon Kagaku Kaishi 1981 Volume 1981, Issue 4 Pages 616-618
Takashi KORENAGA, Hisayoshi IKATSU

Abstract: Use of silver salt was examined to enhance reliability of the flow injection analysis (FIA) for the chemical oxygen demand with potassium permanganate (COD-FIA-Mn). To compare with CODm based on a Japan Industrial Standard, pertinent operating conditions of the FIA were investigated for waste water samples by using D-glucose or lactose as a standard. It has turned out that the most reliable results could be obtained by adding 0.05% of silver nitrate into the flow of acidic permanganate solution as a catalyst. Under the proposed conditions, chloride up to 1000 mg L-1 did not interfere with the determination. The newly proposed FIA method could be successfully applied to industrial waste water samples.
Chemical oxygen demand d-Glucose Lactose Method comparison Standard method Interferences

"Determination Of Hydride-forming Elements At Ultratrace Levels By Flow Injection Hydride-generation Atomic Absorption Spectrometry With Online Ion-exchange Column Preconcentration"
Quim. Anal. 1989 Volume 8, Issue 2 Pages 191-199
Zhang, S.;Xu, S.K.;Fang, Z.L.

Abstract: Soil samples, prepared by refluxing for 2 h, and acidified, filtered water samples were merged with ammonium acetate buffer solution (0.2 M at pH 5 or 1 M at pH 7 for Se or Bi, respectively) and pre-concentrated on dual ion-exchange columns of D-201 (60 to 100 mesh) for Se(IV) or CPG-8Q (60 to 100 mesh) for Bi(III), and eluted with 1 M HCl. The eluates were mixed with 0.5% NaBH4 solution in 0.1% NaOH as reductant and carried by Ar carrier gas into a heated silica atomizer for AAS analysis. The limits of detection were 0.002 and 0.001 µg L-1 for Se(IV) and Bi(III), respectively, and the corresponding coefficient of variation were 1.1 and 1.0% (n = 11). Effects of co-existing ions are tabulated; interference from Cu(II) was overcome by the addition of 0.5% thiourea to the HCl eluent. Overall recoveries from water and soil water extracts were 90 to 108%, except for Bi(III) in waste water (78 to 90%).
Selenium Bismuth Ion exchange Sample preparation Spectrophotometry Column Preconcentration Buffer Interferences Volatile generation Nebulizer Ultratrace Volatile generation

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

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

"Online Analysis Of Caustic Streams By Near Infrared Spectroscopy"
Spectroscopy 1987 Volume 2, Issue 1 Pages 44-48
Watson, E.;Baughman, E.H.

Abstract: The application of near-IR spectrometry in the range 1.5 to 2.4 µm can, with careful choice of analytical and reference wavelengths to obtain the appropriate concentration. range and to avoid interferences by foreign species, be a convenient and useful method for determination of NaOH in, e.g., waste waters and acid-gas scrubbers.
Sodium hydroxide Spectrophotometry Interferences

"Polar Organic Pollutants From Textile Industries In The Waste Water Treatment Process - Biochemical And Physico-chemical Elimination And Degradation Monitoring By LC-MS, FIA-MS And MS-MS"
Trends Anal. Chem. 1996 Volume 15, Issue 8 Pages 349-362
H. Fr. Schr&ouml;der

Abstract: Various analytical methods for the determination of organic pollutants from textile waste waters and their behavior towards physical, chemical and biochemical treatments are considered. Specific MS procedures are presented for the characterization of non-degradable compounds and their reaction products after physico-chemical and biochemical treatment. No elimination was observed using biochemical and adsorptive procedures and there were insufficient results from physico-chemical treatments.
Toxins HPLC Mass spectrometry

"Waste Water Quality Monitoring"
Trends Anal. Chem. 1997 Volume 16, Issue 7 Pages 419-424
Olivier Thomas*, Frederic Th&eacute;raulaz, Victor Cerd&agrave;, Daniel Constant, Philippe Quevauviller

Abstract: A sequential-injected analysis (SIA) system equipped with two spectrophotometric detectors is described for waste water quality monitoring. The system is portable and gives rapid results for global pollution parameters such as COD, dissolved organic C and total suspended solids and the determination of specific compounds such as nitrate and anionic surfactants using a direct UV method, SIA methods were devised for non-absorbent species such as NH3, organic nitrogen, orthophosphates and organic P.
Chemical oxygen demand Carbon, organic, dissolved Nitrate Surfactants Ammonia Phosphorus Nitro compounds Spectrophotometry Portable Sequential injection

"Ammonium Ion Determination Using A Flow-through Ion-selective Electrode In Continuous-flow Analysis. 1. Conventional Application Using A PH Meter And Chart Recorder"
U.K. At. Energy Res. Establ. 1987 Volume 1243, Issue 1 Pages 10-NA
Lister, A.R.

Abstract: A Philips IS 570-NH3/FT flow-through cell, equipped with an NH3 gas-sensing electrode, was evaluated as a replacement for an AutoAnalyzer in the determination of NH4+ in ground water and waste water. The optimum system (illustrated) involved treatment of the air-segmented sample stream (0.42 mL min-1) with an aqueous NaOH (34 g l-1) - EDTA (31.7 g l-1) stream (0.05 mL min-1), and mixing in a coil before measurement. For measured contents of 553 to 1940 µg mL-1 of NH4+ in ground water, the coefficient of variation were 3.3% (n = 10) with intermediate washing of the cell wth 5% citric acid solution. Results agreed fairly well with those by the AutoAnalyzer method.
Ammonium Electrode Method comparison

"New Techniques For Automated Determination Of Ammonium In Effluents"
Vom Wasser 1987 Volume 69, Issue 1 Pages 95-106
Merz, W.;Oldeweme, J.

Abstract: Automated determination of NH4+ in natural or waste water was achieved by(I) continuous-flow analysis and(II) ion chromatography. In method(I), the aqueous sample is mixed with an alkaline carrier stream (25 g of KOH and 10 g of Na2EDTA in 1 l of H2O) to increase the pH to 11 or 12 and convert NH4+ into NH3. The resulting solution is passed along a semi-permeable membrane, across which the NH3 diffuses into H3BO3 solution (1 g l-1). The determination is based on the change in conductivity of this solution Results for natural waters and for effluents agree well with those by conventional techniques, e.g., spectrophotometric and Kjeldahl methods. Alternatively, in method(II), NH4+ is separated from amines and alkali metals on a cation-exchange column of HPIC-CS 1 and HPIC-CG-1 a (Dionex). Detection is effected fluorimetrically after post-column reaction with phthalaldehyde. Monoethanolamine interferes but other amines do not. Considerably lower values are obtained by(II) than by(I).
Ammonium HPIC Fluorescence Spectrophotometry Interferences Method comparison Membrane Post-column derivatization Kjeldahl

"Automated Analyzer ADM300 With Microcomputer-controlled Evaluator AE2-2"
Wasserwirtsch. Wassertech. 1985 Volume 35, Issue 5 Pages 98-99
Mueller, Albrecht; Eulenberg, Horst; Kopprasch, Wolfgang

Abstract: The ADM 300 analyzer for flow-injection anal. of water has a AE2-2 microcomputer-controlled evaluator and can process ~160 samples/day. The flow injection analysis app. can be used for determination of Fe, Mn, NH4+, NO2-, and NO3- in drinking water; P and N determinations in water monitoring; and Fe and P determination in optimization of the use of pptg. agents in wastewater treatment. (SFS)
Ammonium Iron Manganese Nitrate Nitrite Nitrogen Phosphorus Computer Precipitation

"Monitoring Of Dissolved Reactive Phosphorus In Waste Waters By Flow Injection Analysis. 1. Method Development And Validation"
Water Res. 1996 Volume 30, Issue 9 Pages 1959-1964
Richard L. Benson, Yen B. Truong, Ian D. McKelvie* and Barry T. Hart

Abstract: A laboratory-manufactured automated FIA system was used. Wastewater samples (40 µL) were injected into a water carrier stream (C1) and sequentially merged with a further carrier stream of 5.2 g/l KCl/7.1 m/l HCL (C2) then 10 g/l ammonium molybdate/35 ml/l H2SO4 (colorimetric reagent; R1) and 0.2 g/l tin (II) chloride/2 g/l hydrazinium sulfate/28 ml/l H2SO4 (reducing agent; R2). Flow rates were 1.2, 0.58, 0.86 and 0.58 ml/min for C1, C2, R1 and R2, respectively. Detection was at 635 nm. Calibration graphs were linear up to 25 mg/l P; detection limit was 0.05 mg/l. RSD were n=11). Results correlated well with those obtained using a standard batch method.
Phosphorus Spectrophotometry Process monitoring Automation Method comparison

"Monitoring Of Dissolved Reactive Phosphorus In Waste Waters By Flow Injection Analysis. 2. Online Monitoring System"
Water Res. 1996 Volume 30, Issue 9 Pages 1965-1971
Richard L. Benson*, Yen B. Truong, Ian D. McKelvie*, Barry T. Hart, Glenn W. Bryant and William P. Hilkmann

Abstract: Modifications to a method described previously (Ibid, 1996, 30, 1959) are presented. The manifold is illustrated; the main differences are the removal of the carrier stream of KCl/HCl, an increase to an 80 µL injection loop and the use of two solenoid valves for injection. Waste water samples were filtered to 0.2 µm then injected into a water carrier stream. They were then sequentially merged with 10 g/l ammonium molybdate/35 ml/l H2SO4 (colorimetric reagent) and 0.2 g/l tin (II) chloride/2 g/l hydrazinium sulfate/28 ml/l H2SO4 (reducing agent). Detection was at 635 nm. Calibration graphs were linear up to 2 mg/l P; the detection limit was 0.05 mg/l. Details of construction, field testing and validation are presented. Results agreed with those obtained using a validated laboratory method.
Phosphorus Spectrophotometry Standard method Process monitoring

"Flow Injection Turbidimetric Analysis Of Sulfate In Water"
Water SA 1986 Volume 12, Issue 1 Pages 43-50
van Staden JF

Abstract: Three flow injection modifications of the turbidimetric determination of SO42- by precipitation as BaSO4 are described and illustrated. Automated pre-filtration with activated carbon - paper is used for removal of suspended solids, organic substances and color from most samples. Single- and double-channel flow injection systems are suitable for determination of SO42- in heavily colored industrial effluents. For samples with a high SO42- content, automated dialysis provided the best system.
Sulfate Turbidimetry Dialysis Interferences Activated carbon

"Experiences With Automatic N And P Measurements Of An Activated Sludge Process In A Research Environment"
Water Sci. Technol. 1996 Volume 33, Issue 1 Pages 165-173
S. Isaacs and H. Temmink

Abstract: Some of the advantages of on-line automatic measurement of ammonia, nitrate and phosphate for studying activated sludge systems are pointed out with the help of examples of batch experiments. Sample taking is performed by cross-flow filtration and measurement of all three analytes is performed by Flow Injection Analysis (FIA). Two batch set-ups are described. In the first, one of the two 800 l nitrifying/denitrifying tanks of a pilot-scale alternating process is employed as batch reactor, which has the advantage of a high measurement frequency and little preparatory and clean-up effort. The second consists of four 5 l jars connected to the FIA system and allows on-line measurement of ammonia, nitrate and phosphate while performing batch reactions in parallel. Each of the four examples described was designed to study a particular aspect pertaining to Enhanced Biological Phosphate Removal (EBPR): the effect of acetate addition on aerobic P-uptake; the recovery of aerobic P-uptake after a disturbance; the interaction between denitrification and P-release when acetate is added at various rates; and the effect of stored PHB levels on denitrification by phosphate accumulating organisms.
Nitrogen Filtration Automation

"Screening For Non-regulated Organic-compounds In Municipal Waste-water In Goteborg, Sweden"
Water Sci. Technol. 1996 Volume 33, Issue 6 Pages 9-15
Nicklas Pax&eacute;us and Horst Friedrich Schr&ouml;der

Abstract: Organic compounds from influent and effluent wastewater were concentrated on C18 bonded phase cartridges and sequentially eluted with organic solvents of different polarity, About 80% of the toxicity (Microtox) arised from organic matter eluted with ether. Approximately 50% decrease in the overall toxicity of the influent was observed during the treatment process. More than 50 individual compounds were identified in the eluates for both influent and effluent by CC-MS and FIA-MS analysis. Perfume additives to washing powders and cleaning agents and a number of industrial volatile hydrophilic solvents were quantitatively removed by volatilization in the treatment process. Only a partial removal was observed for less volatile compounds (benzophenone, dibutyl formamide, dimethyl quinoline, benzothiazole, phosphate esters) of industrial origin. Substituted phenols, used as antioxidants in both industrial and domestic products were transformed to corresponding -ene-ones in the biological stage of the water treatment process. Polyglycols and polyglycol ether type surfactants are not removed in the activated sludge prosess, only partly transformed to highly persistant acids by oxidation of the terminal hydroxyl function. The treatability in municipal wastewater plants should be paid much more attention when introducing polar non-volatile constituents in new ''environmentally friendly'' water based products or processes. Copyright (C) 1996 IAWQ.
LC GC Mass spectrometry

"Characterization And Monitoring Of Persistent Toxic Organics In The Aquatic Environment"
Water Sci. Technol. 1998 Volume 38, Issue 7 Pages 151-158
H.Fr. Schr&ouml;der

Abstract: The effluent of a biological wastewater treatment plant containing mainly non-eliminable polar compounds was treated using different types of elimination techniques. Pptn./flocculation with ferric salts, adsorption onto lignite coke or powd. activated carbon (PAC) were used besides oxidative treatment steps like ozone (O3) with or without UV radiation and hydrogen peroxide (H2O2) in combination with UV for elimination or degrdn. Sum parameter anal. and substance-specific flow injection mass spectrometry (FIA/MS) were used for monitoring the elimination efficiency. Tandem mass spectrometry (FIA/MS/MS) was applied for identification. No elimination could be observed under all treatment steps applied, but degrdn. by oxidative processes led to improved biodegradability. The results of microtoxicity and daphnia magna toxicity testing after O3/UV and H2O2/UV treatment differed widely.
Organic compounds Mass spectrometry Process monitoring

"Rapid Determination Of Trace Cadmium In Waste Water By FIA - Fluorimetry"
Yankuang Ceshi 1991 Volume 10, Issue 3 Pages 200-202
Guo, J.;Zhao, H.;Duan, X.

Abstract: Industrial waste water adjusted to pH 7 by addition of ammonia, water and acetic acid flowed to react with a stream of 0.7 mM 8-hydroxyquinoline-5-sulfonic acid, 0.65 mM hexadecyltrimethylammonium bromide and ammonium acetate buffer of pH 7.18 in a 29.2-m reaction tube before measuring fluorescence intensity at 534 nm (excitation at 391.7 nm) in a 9.8-cm quantitation tube. Linear range was from 0 to 5 µg mL-1 of Cd. Recovery was 95.2 to 98.7%; coefficient of variation was 0.1%. The rate was up to 180 per h. Only Al3+, Fe3+, Hg2+, Zn2+, Cl-, F- and ClO4- interfered. Results were satisfactory and comparable with those of ICP-AES.
Cadmium Fluorescence Buffer Interferences pH 8-hydroxyquinoline-5-sulfonic acid

"Continuous Determination Of Total Soluble Nitrogen In Waste Water Using Online Photo-oxidation And Flow Injection Analysis"
Z. Wasser Abwasser Forsch 1991 Volume 24, Issue 2 Pages 60-65
Hinkamp, S.;Schwedt, G.

Abstract: Samples (100 µL) in a carrier stream were mixed with an alkaline solution of K2SO8 and passed into a UV reactor where both inorganic and organic N-compounds were photo-oxidized to NO3-. Gases arising from the reaction were removed by debubbling and NO3- was measured at 226 nm. The calibration graph was rectilinear from 1 to 50 mg L-1 of N with a detection limit of 0.75 mg mL-1 and a coefficient of variation (n = 5) of 2%. Recoveries were 85%. Waste water was filtered (0.45 µm), diluted 1:25 and a portion (0.1 ml) of the solution was injected into a carrier stream (1.2 mL min-1) of Na2B4O7 - NaOH (pH 9) and mixed with a reagent stream (0.6 mL min-1) of 0.04 M K2S2O8 in a teflon coil (13 m x 0.5 mm). The mixture was exposed to UV light from a low pressure Hg lamp, the N compounds were converted to nitrate and gaseous by-products of the photolysis were removed in a debubbler before passing the solution to a flow-through UV detector operating at 226 nm. Calibration graphs were rectilinear up to 50 mg L-1 of nitrate, urea and aspartic acid and the detection limit was ~0.75 mg l-1. Coefficients of variation were 2% (n = 5). Interference was not present from the organic matrix.
Nitrogen, total Spectrophotometry Filter Interferences Debubbler UV reactor Photochemistry

"Flow-type Equipment With Photometric And Ionometric Detection For Continuous Monitoring Of Natual And Waste Waters"
Zavod. Lab. 1996 Volume 62, Issue 1 Pages 7-10
Moskvin, A.L.;Mozzhukhin, A.V.;Moskvin, L.N.

Abstract: General methods of developing systems for the automated monitoring of aqueous media based on flow and flow injection analysis, are examined. Flow analyzer.s with both photometric and ionometric detection for monitoring natural and waste water are discussed. Optimum systems for these types of analysis are presented. A system using a four-channel peristaltic pump, a changeover tap, deaerator and photometric or ionometric detector is described as an example. Calibration by the additions method is recommended. Algorithms for calculating the concentrations of the analyte in the medium are presented.

"Flow Injection Determination Of Zinc"
Zavod. Lab. 1996 Volume 62, Issue 1 Pages 14-16
Gur'ev, I.A.;Zyuzina, L.F.;Rusyaeva, Y.I.

Abstract: Sample was adjusted to 1 M chloride with 3 M KCl. A standard solution of Zn salt of lower concentration, sample and a standard solution of Zn salt of higher concentration were introduced consecutively to a flow injection system with ionometric detection. The method was used to determine Zn in a zinc-plating electrolyte and the solution produced after washing Zn-plated lamp caps. For determining Zn in waste water, sample (50 ml) was pre-concentrated on an ion-exchange column (2.4 cm x 5 mm i.d.) packed with the cationite KRS-4p (K+ form). RSD were 0.08. It was possible to carry out 10 determinations an hour.
Zinc

"Flow Injection Analysis. Potentiometric Determination Of Copper(II) In Waters"
J. Anal. Chem. 1988 Volume 43, Issue 12 Pages 2200-2205
Shpigun, L.K.;Bazanova, O.V.;Kuzmin, N.M.

Abstract: The flow system described for determination of 0.5 ng mL-1 of Cu in water incorporates a Tecator FIAstar analyzer. linked (by tubing of i.d. 0.5 mm) to a potentiometric cascade-type detector consisting of a Crytur 29-17 Cu(II)-selective electrode, a Ag - AgCl reference electrode and an Orion 811 pH meter. A two-channel manifold with one continuously and one intermittently operated pump is used. The Cu is pre-concentrated online by pumping 500 mL of sample at 8.5 mL min-1 through a 90 µL column packed with Chelex-100 (50 to 100 mesh; NH4+ form), and is then eluted by the injection of 500 µL of 0.5 M HNO3 into the carrier stream. The eluate is merged with a stream of 0.5 M acetate buffer of pH 4.7 (flow rate 2 mL min-1) before entering the detector. The sample throughput is 1 to 45 h-1. Silver and Hg interfere seriously. The coefficient of variation was 5.3% (n = 4) when determining 0.5 to 250 ng mL-1 of Cu in potable water, seawater and effluent waters.
Copper(II) Electrode Potentiometry Chelex Interferences Preconcentration Tecator

"A Multisyringe Flow Injection Method For The Automated Determination Of Sulfide In Waters Using A Miniaturised Optical Fiber Spectrophotometer"
Talanta 2004 Volume 64, Issue 5 Pages 1119-1126
Laura Ferrer, Graciela de Armas, Manuel Mir&oacute;, Jos&eacute; Manuel Estela and V&iacute;ctor Cerd&agrave;

Abstract: In this paper, a fully software-controlled multisyringe flow injection (MSFIA) spectrophotometric system is proposed for the determination of sulfide in environmental and waste waters. The implementation of ancillary solenoid valves into the flow network allows a multitude of injection modalities to be explored, the selected modality being directly dependent on the aim of the assays. The multicommuted sandwich-type approach is introduced in this work as an efficient means to warrant high sensitivity for the particular assay with excellent repeatabilities and a considerable reagent saving. Moreover, a high injection frequency may be easily attained by carrying out a multiple injection modality during a single forward displacement of the piston driver bar. The interfacing of the robust and versatile multisyringe piston pump with an optical fiber plug-in spectrophotometer furnished with a light emitting diode enables the miniaturization of the flow analyzer, which is thus readily adaptable to in-situ and real-time monitoring schemes. The flow method is based on the coupling Fischer's reaction of sulfide with N,N-dimethyl-p-phenylenediamine in the presence of Fe(III) as oxidizing reagent in a 0.7 M HCl medium. Careful selection of the physical and chemical variables enabled coefficients of variations better than 1.5% (n = 10) at the 1 mg L-1 level for both injection modalities. Dynamic working ranges of 0.2-2.0 and 0.5-5 mg L-1 sulfide for sandwich and multiple injection techniques, and detection limits of 0.09 and 0.15 mg l-1, respectively, were obtained. Furthermore, the sandwich modality featured an average slope of 0.43±0.02 l mg-1 calculated from 10 day-to-day calibration plots. This result reveals better sensitivity than other flowing stream methods described in the literature. The multiple injection technique allowed an improvement of the injection throughput up to 80 h-1, although a decrease of sensitivity was concomitantly observed (average slope of 0.17±0.01 l mg-1).The multisyringe flow method was successfully applied to the determination of sulfide in different spiked water matrices (namely, mineral, tap, freshwater, seawater and wastewater) with recoveries ranging from 96 to 104%. Good agreement was also found in water samples between the MSFIA results and those of the batch APHA-standard method.
Sulfide Spectrophotometry Automation Computer Optimization Method comparison Interferences

"Sequential Injection Spectrophotometric Determination Of Orthophosphate In Beverages, Wastewaters And Urine Samples By Electrogeneration Of Molybdenum Blue Using Tubular Flow-through Electrodes"
Anal. Chim. Acta 2004 Volume 510, Issue 1 Pages 61-68
Francisca Mas-Torres, Jos&eacute; Manuel Estela, Manuel Mir&oacute;, Andreu Cladera and V&iacute;ctor Cerd&agrave;

Abstract: A novel and automated sequential injection procedure is proposed for the spectrophotometric determination of orthophosphate without requiring unstable chemical reducing species used in the classical molybdenum blue method. The flowing methodology is based on the on-line generation of the detectable species by electrochemical reduction of the 12-molybdophosphoric acid complex using a stainless steel tubular flow-through working electrode. The established method is linear up to 20 mg/l P, with coefficients of variation (n=10) of 2.4 and 1.8% for 2.0 and 10 mg/l P, respectively. The versatility of the sequential injection method to analyze samples containing high orthophosphate levels has been demonstrated by the implementation of a dilution chamber as well as flow-reversal techniques, yielding relative standard deviations (n=17) better than 2.0% for standards containing 200 and 800 mg/l P. The proposed analyzer. features an extremely wide dynamic range (viz., 0.3-800 mg/l) as well as improved tolerance to silicate interference, so that Si/P ratios higher than 50 are tolerated at the 5% level. Electrochemical conditions, reagent concentrations and physical variables have been thoroughly investigated. The method has been applied to the determination of orthophosphate in wastewaters as well as beverages and biological samples containing high concentrations of the target analyte. The t-test comparison of the means for the developed sequential injection system with electroreduction and both the molybdenum blue classical spectrophotometric batch procedure and inductively coupled plasma-optical emission spectrometric detection selected as external reference methods revealed that there is no evidence of significant differences between the obtained results at the 95% confidence level.
Phosphate Spectrophotometry Sequential injection Method comparison Interferences Flow reversal Gradient technique Mixing chamber Electrochemical reagent generation

"In-line Membrane Separation Method For Sulfide Monitoring In Wastewaters Exploiting Multisyringe Flow Injection Analysis"
Anal. Chim. Acta 2004 Volume 524, Issue 1-2 Pages 89-96
Graciela de Armas, Laura Ferrer, Manuel Mir&oacute;, Jos&eacute; Manuel Estela and V&iacute;ctor Cerd&agrave;

Abstract: A fully automated multisyringe flow injection analysis (MSFIA) system coupled to gas-diffusion (GD) separation is proposed for the spectrophotometric determination of sulfide in urban wastewaters containing suspended solids. No preliminary batch sample treatment is required. The method carried out in a multicommutated system is based on analyte release as hydrogen sulfide from the donor channel of the GD module into a stagnant recipient solution composed of N,N-dimethyl-p-phenylene diamine (DMPD) and Fe(III). The methylene blue dye generated in-line via oxidative coupling is subsequently delivered downstream to a miniaturized flow-through light-emitting diode (LED)-based optical fiber plug-in spectrophotometer. The effect of various experimental variables on gas transfer across the membrane and concentration enhancement in the receiver solution via iterative flow reversals are discussed. Under the optimized chemical and hydrodynamic variables, the GD-MSFIA method features coefficients of variation better than 0.8% (n=10) at the 10 mg L-1 level, a linear working range of 0.5-20 mg L-1 sulfide, a 3s blank-detection limit of 0.03 mg L-1 and an injection throughput of 13 h-1 for a sample volume of 700 µl and a forward flow mode. The analytical performance of the proposed GD-MSFIA system is also critically compared with that of in-line dialysis separation schemes using passive semi-permeable hydrophilic membranes. Accuracy was assessed by using the batch APHA-AWWA-WPFC standard method as an external reference.
Sulfide Spectrophotometry Light emitting diode Optical fiber Multisyringe Optimization Gas diffusion Method comparison

"Flame Atomic Absorption Determination Of Lead Through On-line Preconcentration By Surfactant Mediated Glass Wool Retention"
Int. J. Environ. Anal. Chem. 2006 Volume 86, Issue 1-2 Pages 45-52
Christos Z. Katsaounos, Evangelos K. Paleologos, Miltiades I. Karayannis

Abstract: This work reports on the fabrication of a mini column packed with controlled pore glass and glass wool, and its application for the on-line pre-concentration of lead with the aid of an anionic surfactant (sodium dodecyl sulphate, SDS) and AAS detection. Lead reacts with SDS in a high-ionic-strength environment, and the product is retained and pre-concentrated on a high-surface-area substrate like glass wool. The intervention of controlled pore glass increases the active surface of glasswool and prevents its accumulation into a sticky mass after wetting. Washing the mini column with a methanolic solution of HNO3, causes the retained micellar face to be eluted, and consequently the lead content can be determined with AAS. A pre-concentration factor of 50 along with a signal enhancement due to the combined presence of SDS and methanol yields a detection limit of 1.5 µg/L-1. The correlation coefficient of the calibration curve is 0.999, and the linear range 5-500 µg/L-1. The method was used for the determination of lead in water and wastewater with good results.
Lead Spectrophotometry Controlled pore glass Glass microfiber Preconcentration Column Surfactant

"On‐Line Spectrophotometric System Based On Pseudo Liquid Drop And Handheld CCD Spectrometer For Monitoring Formaldehyde Level In Wastewater"
Instrum. Sci. Technol. 2005 Volume 33, Issue 3 Pages 297-307
Zaide Zhou, Guanping Zhong, Qing Tan, Yuan Li, Xiandeng Hou

Abstract: An on-line spectrophotometric system, based on a handheld CCD (charge coupled device) spectrometer and a liquid drop, was constructed for the purpose of monitoring of formaldehyde in wastewater. The liquid drop device was used as a reactor and optical cell for the spectrophotometric measurements to solve the problem of colored species stained onto a traditional quartz optical cell. To overcome the drawback of short optical path of a traditional liquid drop, a simple flow-through type optical cell with open ends was designed and used as a prolonged "liquid drop," i.e., a "pseudo" liquid drop. By using such a pseudo liquid drop, the advantages of a windowless optical cell of a liquid drop are retained, while the optical path is increased to over 7 times of that of a traditional liquid drop. The limits of detection for formaldehyde were found to be 0.05 µg/mL with the liquid drop, and 0.01 µg/mL with the pseudo liquid drop. The method was applied to the determination of formaldehyde in wastewater with satisfactory analytical results.
Formaldehyde Spectrophotometry Flowcell Capillary

"Application Of Some Recently Synthesized 9,10-anthraquinone Derivatives As New Class Of Ionophores Responsive To Lead (II) Ion"
IEEE Sens. J. 2005 Volume 5, Issue 3 Pages 392-397
Barzegar, M. Mousavi, M.F. Khajehsharifi, H. Shamsipur, M. Sharghi, H.

Abstract: Lead-selective solvent polymeric membrane electrodes, based on some recently synthesized 9,10-anthraquinone derivatives, are described. The electrode exhibits a good Nernstian response for Pb (II) ions over a wide concentration range of 1.0 x 10^-6 - 1.0 x 10^-2 M with a slope of 28.9 mV decade-1. The potential-pH profile of membrane based on 1-hydroxy-2-({2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}methyl)anthra-9,10-quinone (A3) demonstrated a lack of H+ interference within a wide pH range (1.5-6.8). The detection limit is 6.7 x 10^-7 M. The developed sensor has a very short response time (2.0 s), and it can be used as a working electrode in a flow injection system. The lifetime of the proposed sensor is 120 days (without any considerable divergence in potentials) with good reproducibility (SD=±0.1 mV). The proposed sensor revealed good selectivity for Pb (II) over a wide variety of other metal ions. It can be used as an indicator electrode in the potentiometric titration of lead ions, with EDTA, oxalate, chromate, and hydroxide ions, and in direct determination of lead in a wastewater sample.
Lead(2+) Electrode Electrode Detector Interferences

"Sequential Injection System For On-line Analysis Of Total Nitrogen With UV-mineralization"
Talanta 2003 Volume 59, Issue 2 Pages 319-326
M. T. Oms, A. Cerd&agrave; and V. Cerd&agrave;

Abstract: An automatic method for the determination of total nitrogen in wastewater by sequential injection analysis and mineralization with UV radiation has been developed. The method is based on the mineralization of the samples with sodium persulphate in basic medium under UV radiation. Small volumes of sample and reagents are firstly aspirated into a single channel and then propelled by flow reversal to the UV reactor and then to the detector. The organic and inorganic nitrogen compounds are oxidized to nitrate that is then measured at 226 nm. The sequential injection procedure has been optimized and the factors affecting the efficiency of the oxidation have been studied with a number of test substances with different chemical structures and properties. Solutions in the concentration range 1-56 g L-1 of nitrogen can be analyzed with the described procedure. The sample rate is of 30-40 samples h-1. The LOD is 0.6 mg L-1 N and the reproducibility is 1.8% (28 mg L-1 N). Organic carbon in the form of glucose was added to a number of test solutions to study the potential interference of organic matter.The method was compared with the Kjeldahl digestion method by analyzing 15 wastewater samples with both methods. The nitrate and nitrite content of the non-oxidized samples were subtracted from the corresponding nitrogen content determined after photo-oxidation and the value compared with the Kjeldahl nitrogen content.
Nitrogen, total Spectrophotometry Interferences UV reactor Kjeldahl Method comparison Optimization

"Interfacing In-line Gas-diffusion Separation With Optrode Sorptive Preconcentration Exploiting Multisyringe Flow Injection Analysis"
Talanta 2005 Volume 68, Issue 2 Pages 343-350
Laura Ferrer, Graciela de Armas, Manuel Mir&oacute;, Jos&eacute; Manuel Estela and V&iacute;ctor Cerd&agrave;

Abstract: An automatic multisyringe flow injection analysis (MSFIA) system coupling a flow-through optical fiber diffuse reflectance sensor with in-line gas-diffusion (GD) separation is proposed for the isolation, pre-concentration and determination of traces of volatile and gas-evolving compounds in samples containing suspended solids, with no need for any preliminary batch sample treatment. The flowing methodology overcomes the lost of sensitivity of the in-line separation technique, when performed in a uni-directional continuous-flow mode, through the implementation of disk-based solid-phase extraction schemes. The high selectivity and sensitivity, the low reagent consumption and the miniaturization of the whole assembly are the outstanding features of the automated set-up. The proposed combination of techniques for separation, flow analysis, pre-concentration and detection was applied satisfactorily to sulfide determination in environmental complex matrixes. The method based on multicommutation flow analysis involves the stripping of the analyte as hydrogen sulfide from the donor channel of the GD-module into an alkaline receiver segment, whereupon the enriched plug merges with well-defined zones of the chormogenic reagents (viz., N,N-dimethyl-p-phenylenediamine (DMPD) and Fe(III)). The in-line generated methylene blue dye is subsequently delivered downstream to the dedicated optrode cell furnished with a C18 disk, while recording continuously the diffuse reflectance spectrum of the pre-concentrated compound. This procedure provides a linear working range of 20-500 µg l-;1 sulfide with a relative standard deviation of 2.2% (n = 10) at the 200 µg L-;1 level, and a detection limit of 1.3 µg L-;1.
Sulfide Optrode Gas diffusion Preconcentration Multisyringe Multicommutation

"Flow-through Optical Fiber Sensor For Automatic Sulfide Determination In Waters By Multisyringe Flow Injection Analysis Using Solid-phase Reflectometry"
Analyst 2005 Volume 130, Issue 5 Pages 644-651
Laura Ferrer, Graciela de Armas, Manuel Mir&oacute;, Jos&eacute; Manuel Estela and V&iacute;ctor Cerd&agrave;

Abstract: A software-controlled flow-through optical fiber diffuse reflectance sensor capitalized on the implementation of disk-based solid-phase pre-concentration schemes in a multisyringe flow injection analysis (MSFIA) set-up is proposed for the trace determination of sulfide in environmental waters and wastewaters. The fully automated flowing methodology is based on Fischer's coupling reaction of sulfide with N,N-dimethyl-p-phenylenediamine (DMPD) in the presence of Fe(III) as oxidizing reagent in a 0.5 M HCl medium. The on-line generated methylene blue dye is subsequently delivered downstream to a dedicated optode cell furnished with an octadecyl-chemically modified (C18) disk, while continuously recording the diffuse reflectance spectrum of the pre-concentrated compound. A double regeneration protocol is finally executed to warrant minimum background noise and negligible baseline. Under the optimized chemical and hydrodynamic conditions, the optosensing MSFIA method features coefficients of variation better than 0.7%(n= 10) at 50 µg l-1 concentration, a linear working range of 20-200 µg L-1 sulfide, a 3s blank detection limit of 2.9 µg l-1 sulfide and an injection throughput of 8 h-1 for a pre-concentration sample volume of 2.9 mL. The interfacing of the robust and versatile multisyringe flow injection-based optode with a plug-in spectrophotometer furnished with a light emitting diode assures the miniaturization of the overall flow analyzer, which is, thus, readily adaptable to real-time monitoring schemes. The potential of the multisyringe flow method was assessed via the determination of sulfide traces in water samples of different complexity (namely, freshwater, seawater and wastewater).
Sulfide Optrode Spectrophotometry Multisyringe Computer C18

"Mercury Determination By CV-AAS In Wastewater And Sewage Sludge From A Stabilization Pond System"
Fresenius J. Anal. Chem. 1996 Volume 355, Issue 3-4 Pages 319-320
Katiuska Araujo, Marinela Colina, Rom&aacute;n Mazurek, Jos&eacute; Delgado, Hilda Ledo, Elizabeth Gutierrez and Len&iacute;n Herrera

Abstract: The mercury concentrations in wastewater and sewage sludge of a stabilization pond system have been evaluated. The system is built by three parallel facultative ponds followed by two systems of three maturation ponds in series. The samples of wastewater and sludge were digested using nitric acid and placed into a Parr-type bomb for 4 h at 110°C. Mercury was measured by Cold Vapour Atomic Absorption Spectrometry (CV-AAS) at 253.7 nm with sodium tetrahydroborate as reductant. The methodologies were checked with an USEPA quality control sample, a standard reference material from NIST and with another method of mineralization (cold mineralization) showing good results. Concentrations of mercury in wastewater between 1.47 ± 0.75 µg L-1 have been found at the entrance of the system and 0.74 ± 0.0 µg L-1 at the exit, while in sludge the results were between 0.29 ± 0.12 µg kg-1 in the facultative pond and 0.04 ± 0.02 µg kg-1 in the second maturation pond (exit).
Mercury Spectrophotometry Method comparison Reference material