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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Sea

Classification: Environmental -> water -> sea

Citations 312

"Stripping Voltammetry For The Determination Of Trace Metal Speciation And In-situ Measurements Of Trace Metal Distributions In Marine Waters"
Anal. Chim. Acta 1999 Volume 400, Issue 1-3 Pages 381-397
Eric P. Achterberg and Charlotte Braungardt

Abstract: Progress in marine chemistry has been driven by improved sampling and sample handling techniques, and developments in analytical chemistry. Consequently, during the last 20 years our understanding of marine trace metal biogeochemistry has improved a great deal. Stripping voltammetric techniques (anodic stripping voltammetry and adsorptive cathodic stripping voltammetry) have made an important contribution to this understanding. The selectivity and extremely low detection limits have made stripping voltammetry a widely used technique for trace metal speciation and trace metal distribution measurements in seawater. Stripping voltammetry is very suitable for ship-board and in-situ applications because of the portability, low cost and capability for automation of the voltammetric instrumentation. Future developments in stripping voltammetry can be expected in the field of stand-alone submersible voltammetric analyzer.s, capable of continuous trace metal measurements. Future applications of stripping voltammetry can be found in the interactions between trace metal speciation and growth and the functioning of organisms in pristine and metal polluted marine waters.
Metals Voltammetry Electrode Electrode Chemiluminescence Portable Speciation Review

"A Flow Injection-fluorometric Method For The Determination Of Ammonium In Fresh And Saline Waters With A View To In Situ Analyses"
Water Res. 2001 Volume 35, Issue 7 Pages 1777-1785
Alain Aminot, Roger Kérouel and Dominique Birot

Abstract: A version of the orthophthaldialdehyde-fluorescence ammonium determination for flow injection analysis (FIA) is presented here, with a view to its use for in situ, low-power consumption systems, Thus, the reaction temperature was limited to 30°C and FIA was used in stop-Bow mode (3 min stop). The calibration is linear up to 50 µmol L-1, but concentrations up to 100 µmol L-1 can be measured. Repeatability is around 1% in the range of 0.5-4 µmol L-1 and the detection limit is about 0.03 µmol L-1 Over the salinity range of 5-35 (seawater practical salinity scale) the salt effect is almost negligible (within±2%); and below salinity of 5 it increases to a maximum of -9% in fresh water compared to seawater. Hydrogen carbonate, dissolved oxygen and turbidity (either suspended sediments or phytoplankton cells) have almost no adverse effect in a wide range of concentrations, covering most natural water conditions. Relative interference of primary amines is negligible and mercury (a common sample preservative) does not depress the signal up to 20 mg L-1 Hg II. Sulfide, that may be present in areas with anoxic waters, depresses the signal only slightly and linearly (-9% at 100 µmol L-1 S2-). The method appears to be convenient for the determination of ammonium in most coastal, estuarine and fresh waters. Sample throughput is 9 h-1. The performance of the method can be improved, either by increasing the reaction time (low throughput) or, if enough energy is available, by increasing the reaction temperature (non-stop-flow mode, high throughput). Combining FIA and fluorometry appears to be interesting for in situ determination (submersible devices) of dissolved compounds in environments with variable salinity and turbidity (especially coastal and estuarine waters). (C) 2001 Elsevier Science Ltd. All rights reserved.
Ammonium Fluorescence Interferences Optimization Method comparison Reagent stability Remote instrument

"Simultaneous Preconcentration And Speciation Of Iron(II) And Iron(III) In Water Samples By 2-mercaptobenzimidazole-silica Gel Sorbent And Flow Injection Analysis System"
Anal. Chim. Acta 2000 Volume 424, Issue 2 Pages 233-242
H. Bagheri, A. Gholami and A. Najafi

Abstract: 2-Mercaptobenzimidazole, loaded on silica gel (MBI-SG) was used for pre-concentration and speciation of iron(II) and iron(III) in water samples. The speciation is based upon selective retention of iron(III) on MBI-SG sorbent and quantitatively passing iron(II) ions. This type of sorbent was not only capable of separating theses two ions but also could concentrate them. The adsorbed iron(III) on MBI-SG was desorbed from the column by an SCN- solution and transferred to the detection device. The effluent, then, was treated with hydrogen peroxide to oxidize iron(II) into iron(III) and subsequently was pumped through the MBI-SG column. A home-made flow injection system was coupled with a UV-VIS and an atomic absorption spectrometer, simultaneously. This method was applied to four different water samples and sub-ppb detection limit, high accuracy (>99% recovery), good precision (RSD < 5%), and good potential for automation were observed.
Iron(2+) Iron(III) Spectrophotometry Spectrophotometry Immobilized reagent Preconcentration Silica gel Speciation Complexation

"Determination Of Arsenic Species In Seawater By Flow Injection Hydride Generation In Situ Collection Followed By Graphite Furnace Atomic Absorption Spectrometry - Stability Of As(III)"
Anal. Chim. Acta 2000 Volume 418, Issue 1 Pages 19-31
Jean Yves Cabon and Nolwenn Cabon

Abstract: Dissolved arsenic is present in seawater at the 1 µg L-1 level in various chemical forms: mainly, As(III) and As(V) inorganic arsenic, MMA, DMA, and eventually, unknown organic compounds. The concentrations of the minor arsenic species are well below the detection limit of graphite furnace atomic absorption spectrometry (GFAAS). Therefore, a pre-concentration/separation step is generally required before their determination. In this study, arsenic species were determined in seawater by flow injection hydride generation (FI-HG), collection within the graphite furnace, followed by atomic absorption spectrometry. This protocol permitted a pre-concentration factor of about 1000 lowering the detection limit of arsenic in seawater to about 1.5 ng L-1 for a 10 mi sample volume under optimized experimental conditions. Based on the different responses of arsenic species towards hydride generation, an experimental protocol for arsenic speciation was proposed. Total arsenic could be determined after a thermal or a UV irradiation treatment in an alkaline persulfate medium after the conversion of all arsenic species to inorganic As(V). Total hydride-reactive species (As(III), As(V), monomethylarsenic (MMA) and dimethylarsenic (DMA)) could be determined for high NaBH4 and HCl concentrations because a similar analytical response was obtained for these individual species. As(III) could be determined alone by performing hydride generation in seawater at a pH of about 7-8. Non-hydride-reactive arsenic species were determined by the difference between total arsenic and hydride-reactive species. According to this analytical protocol, arsenic species were determined in reference estuarine and coastal seawaters. Hydride-reactive arsenic species were the major compounds, probably mainly As(V); this study tended also to confirm the presence of non-hydride-reactive organic species in seawater (15%). We also showed that As(III) was not stable in acidified seawater and was also slowly converted to As(V) in a coastal surface seawater at its natural pH. These results indicated that time and preservation conditions could severely modify the speciation of arsenic in seawater, particularly for the preservation of As(III).
Arsenic(3+) Arsenic(5+) Dimethylarsenic Monomethylarsine Spectrophotometry Speciation Preconcentration Reference material Optimization

"Dual Wetting-film Multi-syringe Flow Injection Analysis Extraction - Application To The Simultaneous Determination Of Nitrophenols"
Anal. Chim. Acta 2001 Volume 438, Issue 1-2 Pages 103-116
Manuel Mir&oacute;, Andreu Cladera, Jos&eacute; Manuel Estela and V&iacute;ctor Cerd&agrave;

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

"Synthetic Zeolites As Sorbent Material For On-line Preconcentration Of Copper Traces And Its Determination Using Flame Atomic Absorption Spectrometry"
Anal. Chim. Acta 2000 Volume 403, Issue 1-2 Pages 249-258
Yaneira Petit de Pe&ntilde;a, Wilmer L&oacute;pez, Jos&eacute; Luis Burguera, Marcela Burguera, M&aacute;ximo Gallignani, Rosario Brunetto, Pablo Carrero, Carlos Rondon and Freddy Imbert

Abstract: This work assesses for the first time the potential of synthetic zeolites as adsorptive material for the pre-concentration of copper traces. This involves the formation of a copper chelate, its adsorption on sodium lynde Type A (Na-LTA) and sodium faujasite Type X (Na-Fau) synthetic zeolite minicolumns, and its elution with 300 µl of methyl isobutyl ketone. Using 5-80 mg of either sorbents materials with a loading time of 2 min per sample pre-concentration factors of copper ranging from 35-125 for Na-LTA and 3065 for Na-Fau were readily achieved related to the direct introduction of aqueous solutions into an atomic absorption spectrometer. To evaluate the performance of these materials, a flow injection system was used for samples of water from different sources, and the accuracy was assessed through recovery experiments and the analysis of certified reference materials. A parallel experiment was performed with polygosyl bonded silica reversed-phase sorbent with octadecyl functional groups (RP-C-18) as sorbent in the minicolumn in order to study the performance of this. well-known material as a reference for the new sorbents. The 3s detection limits, relative standard deviation and linear calibration graphs were, respectively, 0.1 ng mL-1, 2.6% and 2.5-30 ng mL-1 for Na-LTA and 0.4 ng mL-1, 2.8% and 2.5-40 ng mL-1 for Na-Fau for pre-concentration times of 2 min.
Copper Spectrophotometry Preconcentration Activated carbon Reference material C18 MIBK Column

"A Shipboard Method For Arsenic Speciation Using Semi-automated Hydride Generation Atomic Fluorescence Spectroscopy"
Anal. Chim. Acta 2000 Volume 409, Issue 1-2 Pages 215-226
Alison M. Featherstone, Paul R. Boult, Barry V. O'Grady and Edward C. V. Butler

Abstract: The development of a semi-automated batch HG-AFS method for the shipboard determination of As(III), As(V), MMA and DMA is described. Procedures in the analytical sequence including addition of NaBH4 to samples, cooling and heating the U-trap used for pre-concentration and separation of the arsines, and logging the AFS output are automated. Overall control of the automated tasks into a logical analytical sequence is achieved using a commercially available data acquisition and control package, WORKBENCHMAC™. Further modifications required for the method to be adapted to shipboard use, including the use of a hydrogen generator, are also detailed. This method shows a number of advantages over a previously reported manual HG-AFS method including, shorter sample throughput time, increased precision and most significantly, ease of use under shipboard conditions. The semi-automated method was operated on the RSV Aurora Australis during a Southern Ocean voyage in March 1998. Arsenic measurements from a surface transect between 42°C and 55°S along 141°30E, are presented. Application of the method to more routine laboratory use is also discussed.
Arsenic(3+) Arsenic(5+) Dimethylarsenic Monomethylarsine Fluorescence Automation Speciation Remote instrument Preconcentration Volatile generation

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

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

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

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

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

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

"The Retention Of Metal Species By Different Solid Sorbents - Mechanisms For Heavy Metal Speciation By Sequential Three Column Uptake"
Anal. Chim. Acta 2000 Volume 411, Issue 1-2 Pages 223-237
O. Abollino, M. Aceto, C. Sarzanini and E. Mentasti

Abstract: An apparatus consisting of three columns packed with different substrates, namely an anion exchange resin, a reversed phase sorbent and a chelating ion exchange resin, was developed. The retention of cadmium, copper and lead onto the substrates at different pH conditions was investigated, first by considering each column separately, then by connecting them in series. The aim of the study is to distinguish among species with different charge or chemical behaviour. Experiments were performed with the free metal ions, their anionic complexes with EDTA and 8-hydroxyquinoline-5-sulphonic acid, and their neutral complexes with 8-hydroxyquinoline. The results obtained were compared with those computed according to the theoretical species distribution of all species as a function of pH. The applicability of the technique to seawater was demonstrated.
Cadmium Copper Lead Spectrophotometry Speciation Solid phase extraction Preconcentration 8-Hydroxyquinoline Complexation C18

"Determination Of Trace Levels Of Dissolved Vanadium In Seawater By Use Of Synthetic Complexing Agents And Inductively Coupled Plasma-atomic Emission Spectroscopy (ICP-AES)"
Anal. Bioanal. Chem. 2002 Volume 374, Issue 5 Pages 873-878
Ghiasse Abbasse, Baghdad Ouddane, Jean Claude Fischer

Abstract: In the determination of traces of dissolved vanadium in complex matrices such as seawater, separation and enrichment from the matrix is of special importance. A wide variety of methods has been proposed for pre-concentration, depending to the nature of samples and the methods to be used for measurement. Among these methods separation techniques based on sorption on to chelating resins seem convenient, rapid and capable of achieving a high concentration factor. The methods proposed in this paper are based on the transformation of all dissolved vanadium species in seawater into organic complexes by use of synthetic complexing agents such as dithizone, luminol, or 8-hydroxyquinoline; the resulting vanadium-organic complexes were sorbed on to a C-18 column at a flow rate of 5 mL min^-1. The vanadium sorbed on the C-18 columns was then stripped by use of nitric acid (2 mol L^-1) and analyzed by inductively coupled plasma-atomic emission spectroscopy, ICP-AES. This method was optimized and use of other chelating resins, such as chelamine, chelex-100, and immobilized 8-hydroxyquinoline and was compared by passing seawater samples directly over the resins. The experimental conditions (pH, acid used for elution, and contact time between the liquid sample and the resin) were optimized. The results were compared for all the resins used and were indicative of excellent and coherent reproducibility.
Vanadium Spectrophotometry 8-Hydroxyquinoline Chelex C18 Immobilized reagent Optimization Preconcentration Chelamine

"Fluorimetric Determination Of Dissolved Aluminum In Natural Waters After Liquid-liquid Extraction Into N-hexanol"
Anal. Chim. Acta 2000 Volume 405, Issue 1-2 Pages 31-42
J. Zhang, H. Xu and J. L. Ren

Abstract: A sensitive and selective extraction-fluorimetric method for the determination of trace amount of dissolved aluminum in natural waters is developed in this study. Aluminum-lumogallion complex (Al-LMG) is extracted into n-hexanol, and the fluorescence can be enhanced substantially up to 20-fold. Compared to other publications in the literature, the method reported here is free from matrix effects, and the interference from iron and fluoride has been minimised successfully by Be2+ and o-phenanthroline, respectively. The detection Limit of dissolved Al is 0.25 nM, which is one order of magnitude lower than the traditional fluorescence techniques, with a precision of 5% at an Al level of 40 nM and 6.7% at an Al level of 1.0 nM in routine analyzes. The inter-calibration with electro-thermal atomic absorption spectrometry (ETAAS) technique for a variety of natural water samples shows a difference of 5-10%. The analysis of international SRM 1643C reference material by the method developed here provides a result consistent with the certified value. The successful inter-laboratory calibration practice demonstrates again the merit of present analytical procedure for the determination of Al in environmental and marine sciences.
Aluminum, soluble Fluorescence Interferences Method comparison

"Determination Of Ultra-trace Amounts Of Cobalt In Seawater By Graphite Furnace Atomic Absorption Spectrometry After Pre-concentration With Ni/8-quinolinol/1-nitroso-2-naphthol Complex"
Anal. Chim. Acta 2000 Volume 407, Issue 1-2 Pages 147-153
Qiangbin Zhang, Hirotsugu Minami, Sadanobu Inoue and Ikuo Atsuya

Abstract: A sensitive and accurate method for the determination of ultra-trace amounts of cobalt in seawater is described. Ultra-trace amounts of cobalt were pre-concentrated by co-precipitation with a combination of 8-quinolinol and nickel as a carrier element and 1-nitroso-2-naphtol as an auxiliary complexing agent. The co-precipitates obtained were directly measured by graphite furnace atomic absorption spectrometry using the solid-sampling technique. The co-precipitation conditions for ultra-trace amounts of cobalt with Ni/8-quinolinol/1-nitroso-2-naphtol complex were investigated in detail. It was found that ultra-trace amounts of cobalt are co-precipitated quantitatively with Ni/8-quinolinol/1-nitroso-2-naphtol complex in the pH range of 5.5-8.5. The concentration factor by the co-precipitation reached about 33,000-fold for 1000 mL of the aqueous sample. The proposed method has been successfully applied to the determination of ultra-trace amounts of cobalt in seawater, and the detection limit for cobalt which was defined as the concentration calculated from three times of the standard deviation of the procedural blanks, is 1 ng/l for 1000 mi portions of seawater samples.
Cobalt Spectrophotometry Preconcentration Coprecipitation Optimization

"Simultaneous Spectrophotometric Determination Of Nitrite And Nitrate By Flow Injection Analysis"
Anal. Chim. Acta 1979 Volume 110, Issue 1 Pages 123-128
Leif Anderson

Abstract: The flow injection principle is used in the photometric determination of nitrite and nitrate with sulfanilamide and N-(1-naphthyl)ethylenediamine as reagents. An on-line Cu-coated Cd reductor reduces nitrate to nitrite. The detection limit is 0.05 µM for nitrite and 0.1 µM for nitrate at a total sample volume of 200 µL. Thirty samples can be analyzed/h with a relative precision of ~1%.
Nitrate Nitrite Spectrophotometry Suspended particulate matter Reduction column

"The Determination Of Sulfate By Flow Injection Analysis With Exploitation Of PH Gradients And EDTA"
Anal. Chim. Acta 1980 Volume 114, Issue 1 Pages 319-323
S. Baban, D. Beetlestone, D. Betteridge and P. Sweet

Abstract: A modified method for the turbidimetric determination of sulfate as BaSO4 is proposed. The carrier stream is an alkaline Ba-EDTA solution; the sample zone is sufficiently acidic to allow precipitation of BaSO4. The excess of EDTA in the carrier stream ensures that residual ppt. is redissolved and the system kept clean.
Sulfate Turbidimetry Precipitation pH gradient EDTA

"Determination Of Total Primary Amines In Seawater And Plant Nectar With Flow Injection Sample Processing And Fluorescence Detection"
Anal. Chim. Acta 1982 Volume 142, Issue 1 Pages 299-304
Robert L. Petty, Wiliam C. Michel, Jeffrey P. Snow and Kenneth S. Johnson

Abstract: Flow injection sample processing is used with fluorescence detection for the determination of total primary amines in seawater and nectar. The effects of carrifer stream flow rate and dispersion tube length on sensitivity and sampling rates were studied. Relative responses of several amino acids and other primary amines were determined using two dispersion tube lengths. Linear calibration curves were obtained over the ranges 0-10^-6 M and O-1O-5 M glycine. Precisions of better than 2% at 10^-6 M and a detection limit of 1 x lO-8 M glycine were obtained. Applications to the analysis of seawater from the vicinity of a baited lobster trap and diluted nectar samples from Erythrina sp. are described.
Amines, primary, total Fluorescence

"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

"An Efficient Flow Injection System With Online Ion-exchange Preconcentration For The Determination Of Trace Amounts Of Heavy Metals By Atomic Absorption Spectrometry"
Anal. Chim. Acta 1984 Volume 164, Issue 1 Pages 23-39
Zhaolun Fang, J. Rika and E. H. Hansen

Abstract: The flow injection system described (with diagrams) incorporated a multi-functional eight-channel rotary valve that permitted simultaneous loading of duplicate samples on to two identical columns (35 mm x 2.8 mm). Sequential elution was then effected by intermittent pumping with use of two pumps that were controlled by a dual-channel timer, and the eluate was analyzed by flame AAS Columns of Chelex-100 and of chelating ion-exchange resins based on salicylic acid and quinolin-8-ol were used for the pre-concentration of Cu, Zn, Pb and Cd from seawater. The degree of pre-concentration ranged from 50 to 105-fold at a sampling rate of 60 h-1, and the limits of detection were typically 0.07 to 0.09, 0.03 to 0.04, 0.5 to 0.8 and 0.05 to 0.07 µg L-1 for Cu, Zn, Pb and Cd, respectively.
Metals, heavy Cadmium Copper Lead Zinc Ion exchange Spectrophotometry Chelation Chelex Resin Preconcentration 8-Hydroxyquinoline

"Determination Of Nickel And Cobalt In Natural Waters And Biological Material By Reductive Chronopotentiometric Stripping Analysis In A Flow System Without Sample Deoxygenation"
Anal. Chim. Acta 1985 Volume 175, Issue 1 Pages 79-88
H. Eskilsson and C. Haraldsson, D. Jagner

Abstract: Samples (100 ml) of natural waters, or portions (0.5 to 5 ml) of acid digests of seawater sediments or bovine liver, were mixed with 3 M NH3 - HCl buffer (pH 9.2) and 0.1 M dimethylglyoxime(I) solution in ethanol; Co(III) species formed during acid digestion were reduced with NaBH4. Electroanalysis was performed in a thin-layer flow cell with a vitreous-carbon working electrode. The microprocessor-controlled operational sequence included(I) plating of a mercury film on to the carbon electrode;(II) potentiostatic adsorption (at -0.5 V vs. the SCE) of the Ni(II) - and Co(II) - I complexes on to the mercury film; (iii) constant-current reduction of the metal ions in a 5 M CaCl2 medium and simultaneous recording of the working-electrode potential vs. time; (iv) chemical removal of the mercury film; and (v) cleaning of the vitreous-carbon surface. To determine Co in presence of a large excess of Ni, an adsorption potential of -0.75 V vs. the SCE was used. Detection limits (after 70 s of adsorption) were 8.6 ng L-1 for Ni(II) and 10.5 ng L-1 for Co(II).
Nickel Cobalt Potentiometric stripping analysis Electrode Sample preparation Interferences

"A Submersible Flow Analysis System"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 245-257
Kenneth S. Johnson, Carl L. Beehler and Carole M. Sakamoto-Arnold

Abstract: A submersible chemical analyzer. (SCANNER) that is capable of virtually an in situ spectrophotometric determination in seawater has been applied to the determination of silicate by the molybdenum blue method and of S2- by the methylene blue procedure. The coefficient of variation for 0.1 mM silicate and 25 µM-S2- are 0.6 and 0.5%, respectively, in laboratory tests; results are similar for in situ analysis of seawater at a depth of 2500 m. Detection limits are ~0.1 µM.
Silicate Sulfide Spectrophotometry Apparatus Remote instrument Review

"Determination Of Bromide In Natural Waters By Flow Injection Analysis"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 453-457
Torbj&ouml;rn Anf&auml;lt and Sigrid Twengstr&ouml;m

Abstract: The phenol red method with detection at 590 nm is used, optimum sensitivity being obtained at pH 5.2. Concentrations down to 2 µM can be measured. Interference in natural waters is mainly from NH4+, CN- and humic substances. A single reaction coil (60 cm x 0.7 mm) is used, and a simple procedure for the study of interfering species is described.
Bromide Spectrophotometry Interferences

"Cyclic Flow Injection Determination Of Copper With Hexadecyl-trimethylammonium Bromide Micelle-enhanced, Fluorescein-sensitized Chemiluminescence Detection"
Anal. Chim. Acta 1987 Volume 193, Issue 1 Pages 337-341
Masaaki Yamada and Shigetaka Suzuki

Abstract: The cited method was based on measurement of the chemiluminescence arising from the Cu(II)-catalyzed oxidation of β-nitrostyrene(I) by O dissolved in the reagent stream. The sample (20 µL) was injected into 100 mL of reagent solution (1 mM I - 10 mM NaOH - 5 mM hexadecyltrimethylammonium bromide - 40 µM-fluorescein) which was circulated continuously at 3.4 mL min-1 through a flow system with a reservoir open to the air. The chemiluminescence was measured by a photomultiplier tube in a flow cell which was connected to the injection valve by PTFE tubing (5 cm x 1 mm). Calibration graphs were rectilinear for 0.1 ng (detection limit) to 10 ng of Cu(II). In the determination of 1 ng of Cu(II), the coefficient of variation was 2.2% (n = 10). There was little or no interference from Co(II), Fe(II), Cr(III), Ni(II), Fe(III), Mn(II), Cr(VI), Cd, Zn and Pb. The technique was successfully applied to several hundred samples of seawater and zinc powder at a rate of 200 samples h-1.
Copper Chemiluminescence Closed loop Interferences Micelle

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

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

"Determination Of Uranium(VI) In Seawater By Means Of Automated Flow Constant-current Cathodic Stripping A Carbon Fiber Electrodes"
Anal. Chim. Acta 1987 Volume 197, Issue 1 Pages 265-273
Chi Hua, Daniel Jagner and Lars Renman

Abstract: Uranium(VI) is determined in an automated flow system by means of constant-current reductive stripping with a mercury film-coated carbon fiber electrode and catechol as adsorptive reagent at pH 8.6 Interference from iron(III) is eliminated by addition of sulphite. Increased linear range between stripping signal and sample uranium(VI) concentration can be obtained by adding, in the computer, several stripping curves, each obtained after a short period of adsorptive accumulation. It is shown that the hanging mercury drop electrode can be used for the determination of uranium(VI) by means of computerized constant current stripping without the need for inert gas bubbling. The results obtained for uranium(VI) in two reference seawater samples, NASS-1 and CASS-1, were 2.90 and 2.68 µg L-1 with standard deviations (n = 8) of 0.57 and 0.75 µg l-1, respectively.
Uranium(VI) Amperometry Electrode

"Determination Of Nickel, Cobalt, Copper And Uranium In Water By Cathodic Stripping Chronopotentiometry With Continuous-flow"
Anal. Chim. Acta 1987 Volume 199, Issue 1 Pages 59-76
M. P. Newton and C. M. G. Van Den Berg

Abstract: An automated analyzer. with fast data acquisition (250 kHz) is described. Adsorptive collection of surface-active metal complexes on a hanging-mercury-drop electrode is followed by cathodic scans in which a constant current of 0.8 to 60 µA is passed through the working electrode. Copper, U and Ni can be determined in the presence of dissolved O but the sensitivity for Ni is then much reduced, and Co cannot be determined as its peak is superimposed on the O peak. The sensitivity of stripping chronopotentiometry in the presence of dissolved O is similar to that of fast linear-sweep voltammetry in the absence of dissolved O. Detection limits in deaerated seawater are 0.1, 0.1, 1.8 and 1.6 nM for Ni, Co, Cu and U, respectively, using 60-s stirred adsorption and could be lowered further by prolonged collection (300 s). The technique was successfully applied in measuring Ni with continuous-flow in estuarine water.
Nickel Cobalt Copper Uranium Potentiometry Electrode Voltammetry Interferences

"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

"Reagent Injection Flow Analysis: Application To The Determination Of Nanomolar Levels Of Hydrogen Peroxide In Seawater"
Anal. Chim. Acta 1987 Volume 201, Issue 1 Pages 83-94
Kenneth S. Johnson, Carole M. Sakamoto-Arnold, Stewart W. Willason and Carl L. Beehler

Abstract: The method described is a modification of that described by Madsen and Kromis (Anal. Chem., 1984, 56, 2849) and is based on the formation of a colored condensation product of 3-(N-ethylanilino)propanesulfonic acid and 4-aminoantipyrine. The reaction manifold is a reagent-injection system (cf. Johnson and Petty, Ibid., 1982, 54, 1185). Recoveries of 40 nM- and 80 nM-H2O2 from seawater are between 78 and 88%, whilst those from de-ionized water are from 62 to 93% for 210 to 1060 nM-H2O2. The limit of detection is 12 nM.
Hydrogen peroxide Spectrophotometry Reverse

"Automated Determination Of Total Arsenic In Seawater By Flow Constant-current Stripping Analysis With Gold Fiber Electrodes"
Anal. Chim. Acta 1987 Volume 201, Issue 1 Pages 263-268
Chi Hua, Daniel Jagner and Lars Renman

Abstract: Total arsenic in sea water is determined in a fully automated flow system, by means of potentiostatic deposition for 4 min at a 25 µm gold fiber electrode and subsequent constant-current stripping in 5 M hydrochloric acid. Previously the sample is acidified with hydrochloric and arsenic(V) is reduced to arsenic(III) with iodide. During stripping, the potential vs. time transient is recorded with a real-time measurement rate of 26.5 kHz and a potential resolution of 1 mV. Cleaning and regeneration of the gold electrode are fully automated. The total arsenic concentrations in two reference sea waters (NASS-1 and CASS-1) were evaluated by single-point standard addition and found to be 1.58 and 1.14 µg L-1 with standard deviations of 0.39 and 0.28 µg l-1, respectively; certified values are 1.65 ± 0.19 and 1.04 ± 0.07 µg l-1. The arsenic(III) content in these samples was below the detection limit (0.15 µg l-1).
Arsenic, total Amperometry Electrode Automation

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

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

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

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

"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

"Flow Injection Spectrophotometric Determination Of Fluoride Based On Alizarin Fluorine Blue [alizarin Complexan] In The Presence Of Sodium Dodecyl Sulfate"
Anal. Chim. Acta 1989 Volume 219, Issue 2 Pages 329-333
M. E. Leon-Gonzalez, M. J. Santos-Delgado and L. M. Polo-Diez

Abstract: The manifold of the stopped-flow flow injection system is described and illustrated. A 100 µL portion of 0.1 mM La(III) - alizarin complexan solution was injected into a carrier solution containing 50 mg mL-1 of Na dodecyl sulfate, which was subsequently mixed, first with an acetate buffer solution (pH 4.6) and then with the sample containing 0.04 to 1.5 mg L-1 of F-. The stop and delay times of the pumps were 17 and 15 s, respectively. The absorbance peak heights were measured at 574 nm. The calibration graph was rectilinear for 0.08 to 1.2 mg L-1 of F- and the determination limit was 0.05 mg l-1. The coefficient of variation (n = 10) for 0.60 mg L-1 of F- was 0.2%. The method was applied in the determination of F- in seawater and bottled mineral water.
Fluoride Spectrophotometry Stopped-flow Complexation Surfactant

"Flow Injection And Liquid Chromatographic Determination Of Aluminum Based On Its Fluorimetric Reaction With 8-hydroxyquinoline-5-sulfonic Acid In A Micellar Medium"
Anal. Chim. Acta 1989 Volume 225, Issue 2 Pages 339-350
Jos&eacute; Ignacio Garci&aacute; Alonso, Angeles L&oacute;pez Garci&aacute;, Alfredo Sanzmedel and Elisa Blanco Gonzales, Les Ebdon and Phil Jones

Abstract: Reaction of Al with 8-hydroxyquinoline-5-sulfonic acid (I) in cationic micelles of hexadecyltrimethylammonium bromide (II) formed a strongly fluorescent compound and allowed continuous determination of Al in flowing systems. At pH 6.3, with 0.2 mM I and 2 mM II, the detection limit for Al by flow injection analysis was 0.1 ng mL-1. The calibration graph was rectilinear for 100 ng mL-1, and the peak-height precision was 2% for 10 ng mL-1. Interference was greatly decreased compared with the batch method. The reaction was applied to the post-column detection of Al in fresh and high-salinity waters and dialysis fluid by ion chromatography, and for speciation of Al in serum after separation of proteins by ion-exchange LC.
Aluminum Fluorescence Interferences Buffer Speciation 8-hydroxyquinoline-5-sulfonic acid Dialysis Micelle

"Flow Injection Extraction-spectrophotometric Method For The Determination Of Lead And Its Combination With Minicolumn Preconcentration"
Anal. Chim. Acta 1990 Volume 230, Issue 1 Pages 157-162
E. A. Novikov, L. K. Shpigun and Yu. A. Zolotov

Abstract: Two flow injection systems were devised, one without and one with ion-exchange pre-concentration. [2-mm-i.d. glass column of Chelex-100 resin (NH4+ form; 50 to 100 mesh)]. The Pb(II) was extracted from an aqueous HNO3 carrier stream into dicyclohexano-18-crown-6 solution in CHCl3 in a PTFE coil (2 m x 0.5 mm), and after phase separation in a membrane separator the CHCl3 layer was treated with 0.002% dithizone - 0.4% triethanolamine solution in CHCl3 (mixing ratio 3:2) in a 30-cm PTFE reaction coil for absorbance measurement at 512 nm. With ion-exchange pre-concentration. for 79 s, the calibration graph was rectilinear in the range 10 to 200 µg l-1, the detection limit was 5 µg L-1 and the coefficient of variation at 100 µg L-1 was 9% (n = 4). Test applications to analyzes of alloys, soil extracts and seawater are described briefly.
Lead Ion exchange Spectrophotometry Sample preparation Chelex Chelation Resin Crown ether Extraction Column Preconcentration Phase separator Membrane Calibration Detection limit Organic phase detection Dithizone

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

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

"Determination Of Chromium By Online Preconcentration On A Poly (hydroxamic Acid) Resin An Flow Injection Atomic Absorption Spectrometry"
Anal. Chim. Acta 1990 Volume 236, Issue 2 Pages 469-473
Ajay Shah and Surekha Devi

Abstract: Seven poly(hydroxamic acid) resins [Analyst (London), 1985, 110, 501] were evaluated for LC separation of Cr(III) from U(VI) and from multi-component mixtures. Columns (17 cm x 5 mm) containing the resins in H+ form were used, and the flow rate for sorption and elution was 1 mL min-1. At pH 5, U(VI), Fe(III), Zn and Cu(II) were retained on the resin, but ~80% of the Cr(III) passed through. Retained U(VI) was eluted by 1 M HCl, Zn and Cu(II) by 0.1 M HCl and Fe(III) by 3 M HCl. Cross-contamination was observed between Zn and Cu. Tervalent Cr could also be determined by flow injection flame AAS with use of a column (4 cm x 2.5 mm) of poly(hydroxamic acid) resin and a carrier stream of 0.2 M acetate buffer (pH 2) for pre-concentration.; the Cr(III) was then eluted with 1 M HCl for AAS at 357.9 nm. The calibration graph was rectilinear for 10 µL portions of solution containing 20 to 100 ng mL-1 of Cr(III). The flow injection method was used to determine Cr(III) in seawater at pM concentration.
Chromium Spectrophotometry Preconcentration Resin Multicomponent Column pH Buffer Calibration

"Determination Of A Non-ionic Surfactant In Aqueous Environmental Samples By Flow Injection Analysis With Chemiluminescence Detection"
Anal. Chim. Acta 1990 Volume 239, Issue 2 Pages 189-194
J. Steven Lancaster and Paul J. Worsfold, A. Lynes

Abstract: Nonidet AT 85 was determined in seawater, with use of a glass coil flow cell; sample (100 µL) was merged first with borate buffer, pH 10.5, then with 4.45 mM rhodamine B and finally with 0.46 M NaOCl. The luminescence was measured with a photomultiplier. The response was rectilinear up to 50 mg L-1 with a limit of detection of 5 mg L-1 and coefficient of variation (n = 6) from 2.9% to 26.8% for these limits, respectively.
Surfactants, non ionic Chemiluminescence Glass Flowcell Buffer pH Detection limit

"Online Preconcentration And Determination Of Trace Elements By Flow Injection Inductively Coupled Plasma Atomic-emission Spectrometry"
Anal. Chim. Acta 1991 Volume 248, Issue 1 Pages 241-249
S. Caroli, A. Alimonti and F. Petrucci, Zs. Horv&aacute;th

Abstract: Columns (5 cm x 2 mm) of iminodiacetic acid - ethylcellulose chelating resin (I; 100 to 200 mesh) were used to pre-concentrate trace elements in a computer-assisted online flow injection analysis - ICP-AES technique. Elements of clinical and environmental importance (Cd, Co, Cu and Pb) in water, seawater and urine were determined. A 4-way rotary valve assembly was used to fill the column with solution (mixed with 2 M acetate buffer, pH 5.5), elute the analytes with 2 M HNO3, push the eluent plug with a countercurrent flow of water carrier to the excitation source and wash the column. Sample throughput was 10 to 12 h-1. Compared with pre-concentration. on carboxymethylated polyethyleneimine - polymethylenephenylene isocyanate and Chelex 100 resins, the online mode using I gave a 2- to 4-fold improvement in detection limits and a reduced column volume of about a fifth. Detection power is improved at least one order of magnitude for Cd and Pb in seawater.
Cadmium Cobalt Copper Lead Spectrophotometry Column Preconcentration Chelex

"Flow Injection And Continuous-flow Systems To Determine Antimony(III) And Antimony(V) By Hydride-generation Atomic Absorption Spectrometry"
Anal. Chim. Acta 1991 Volume 252, Issue 1-2 Pages 161-166
Mar&iacute;a Beatriz de la Calle Gunti&ntilde;as, Yolanda Madrid and Carmen C&aacute;mara*

Abstract: Antimony(III) and Sb(V) were determined by flow injection and continuous-flow hydride generation AAS and the analytical performance of the two system are compared. The optimum physical and chemical conditons for hydride generation and transport are given for both methods which are more sensitive than the batch system. Total Sb was determined in seawater but Sb(III) was below the detection limit of the proposed method.
Antimony(3+) Antimony(5+) Spectrophotometry

"Online Preconcentration System For Inductively Coupled Plasma Atomic Emission Spectrometry With Quinolin-8-ol And Amberlite XAD-2 Resin"
Anal. Chim. Acta 1992 Volume 258, Issue 2 Pages 237-244
Valerio Porta, Corrado Sarzanini, Edoado Mentasti* and Ornella Abollino

Abstract: An online pre-concentration. system implemented with inductively coupled plasma atomic emission spectrometry (ICP-AES) was studied for water anal. For the retention of metal ions, 8-hydroxyquinoline and Amberlite XAD-2 resin were used. This system improved the detection limits of Cd, Cu, Fe, Mn, Ni, and Zn by a factor of 100, compared with ICP-AES alone. The method was applied to the determination of the above metals in Antarctic seawater. The concentration. was 16 ng Mn/L and 0.4 µg Ni/L, with a precision of 10%.
Cadmium Copper Iron Manganese Nickel Zinc Spectrophotometry Amberlite Resin Preconcentration 8-Hydroxyquinoline

"Determination Of Trace Elements In Seawater By Flow Injection Anodic Stripping Voltammetry Preceded By Immobilized Quinolin-8-ol Silica Gel Preconcentration"
Anal. Chim. Acta 1992 Volume 258, Issue 2 Pages 245-252
Bor-Jian Daih and Hsuan-Jung Huang*

Abstract: The sample (5 or 10 ml), adjusted to pH 1.6 to 7 for Cu, 3 to 4 for Bi or In, or 6 to 7 for Pb, Cd or Zn, was passed through a column (5 cm x 3 mm) of the cited gel, and the metals were eluted with 1.0 M HCl - 0.1 M HNO3 at 0.22 or 0.33 mL min-1. After being mixed with 0.5 M Na acetate the solution was analyzed in a flow-through cell at a vitreous-carbon working electrode. The coefficient of variation (n = 10) for 1.0 µg L-1 of the test ions were from 2.5 to 6.9%. The results on CASS-2 reference seawater gave reasonably good agreement with the certified values for Cd and Cu, but the Pb concentration was larger and the Zn concentration smaller than the certified value. Procedures based on the application of immobilized quinolin-8-ol silica gel and stripping voltammetry were developed for the determination of Cu, Pb, Cd, Bi, In and Zn in seawater. As two concentration steps are involved, better sensitivity and lower detection limits could be achieved with the application of smaller sample volumes. The feasibility and reliability of the procedures were confirmed by the anal. of a near-shore seawater sample and CASS-2 reference seawater.
Copper Lead Cadmium Bismuth Indium Zinc Voltammetry Immobilized reagent 8-Hydroxyquinoline Reference material Silica gel Preconcentration

"Experience With Flow Injection Analysis In Marine Chemical Research"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 307-314
Lilija K. Shpigun*, Irina Ya. Kolotyrkina and Yurij A. Zolotov

Abstract: A review is presented in which diagrams are shown of reversed flow injection systems used for the determination of silicate, phosphate, SO42-, S2- and Mn(II) in seawater; normal flow injection methods are also described for the determination of alkalinity, SO42- and the main nutrient-type constituents in interstitial water from marine sediments. The methods can be carried out successfully on board ship. (37 references). Some results on using flow injection analysis (FIA) in marine chemical investigations are reported. The new modifications of reversed flow injection manifolds for the determination of dissolved silicate, PO33-, SO42-, sulfide, and Mn(II) in seawater samples and normal flow injection methods for the determination of total alkalinity, SO42-, and main nutrient-type constituents in interstitial water samples are described. The use of the proposed procedures for obtaining the concentration. profiles of some important species in seawater and in interstitial water of marine sediments is shown. The advantages of FIA techniques for determining the chemical data in a chemical laboratory aboard a vessel are demonstrated.
Silicate Phosphate Sulfate Sulfide Manganese(II) Review Reverse Portable

"Determination Of Trace Rhenium In Seawater By Inductively Coupled Plasma Mass Spectrometry With Online Preconcentration"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 315-321
Mohammad B. Shabani* and Akimasa Masuda

Abstract: An online column pre-concentration method is described for the determination of Re in seawater by inductively coupled plasma mass spectrometry. Minicolumns of 2 sizes (7 mm x 2 mm i.d. and 14 mm x 2 mm i.d.) containing the anion-exchange resin Dowex 1-X8 were used for the quant. pre-concentration of Re in seawater. The concentrated Re was eluted from the column with HNO3. A simple calibration technique with Lu as internal standard and also isotope dilution were used for the determination of Re in seawater. Enrichment factors of 38- or 101-fold were obtained using 10- or 50 mL seawater samples, respectively., and the relative standard deviations for replicate measurements (n = 3) were 2.62% for natural seawater and 0.34% for synthetic seawater. The detection limits after online pre-concentration of 10 and 50 mL of seawater were 0.27 and 0.1 pg/mL, respectively. Almost no contamination blank signal or matrix interferences were observed
Rhenium Mass spectrometry Preconcentration Interferences Dowex

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

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

"Fully Automated System For The Continuous Monitoring Of Ammonium Ion In Fish-farming Plant Seawater By Flow Injection Analysis"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 345-349
Hideki Muraki*, Keiro Higuchi, Masanori Sasaki, Takashi Korenaga, Kyoji T&ocirc;ei

Abstract: The sample (200 µL) is introduced by an automatic injector into 3.5% NaCl solution as carrier (which has the same relative density as seawater). This stream is merged with aqueous 10% Na salicylate - 1.9% K Na tartrate, then mixed with NaClO solution (6% of active Cl) - 0.5 M NaOH (1:99) in a 2-m reaction coil at 80°C before detection at 600 nm. Calibration is rectilinear for up to 3.0 mg L-1 of ammonium-N, and at 1.0 mg L-1 the coefficient of variation was 0.35% (n = 20). Under the conditions used, common anions, Na+, Ca2+, Mg2+ and Fe3+ do not interfere. The method was applied to fish-farming seawater. An automated system for the continuous monitoring of NH4+ in fish farming plant seawater is described. The sample is introduced into a carrier stream by an automated sample injector and merged with a reagent solution containing Na salicylate and Na nitroprusside. The sample stream is then mixed with a second reagent solution containing NaClO and heated at 50°C. The absorbance of the resulting solution is monitored at 660 nm. The calibration graph was linear up to at least 3.0 mg NH4+-N/L. The relative standard deviation for 20 injections of samples containing 1.0 mg NH4+-N/L was 0.35%. The interference from Ca2+ and Mg2+ was masked with K Na tartrate. The interference due to amino acids and proteins present in fish foods and wastes was eliminated by adjusting the pH to 6-7 when the sample merged with the 1st reagent solution
Ammonia Spectrophotometry Heated reaction Interferences Automation

"Potentiometric Flow Analysis Device Using Membrane-coated Carbon-rod Ion-selective Electrode Detectors"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 399-404
Enju Wang and Satsuo Kamata*

Abstract: To prepare an ion-selective electrode for Cu2+, a carbon rod (7 cm x 4 mm) with a polished tip was coated with a composition containing (by wt.) 3% of tetraisobutylthiuram disulfide, 0.7% of K tetrakis-(4-chlorophenylborate), 63.1% of 2-nitrophenyl octyl ether (I) and 33.2% of PVC; for anions the composition contained 3.3% of propane-1,2-diylbis(diphenylphosphine), 66.7% of I and 30% of PVC. Either electrode was conditioned in 1 mM Cu2+ before use as detector in the PTFE cell of a simple flow system. For the determination of anions, the filtered and diluted sample (30 to 100 µL) was injected into 0.01 M NaH2PO4 as carrier. The peak potential of the electrode was rectilinearly related the log. concentration. of SCN-, ClO4-, NO3- or Cl- over approximately three decades of concentration. For Cu2+, a continuous-flow system was used with the sample stream buffered at pH 6 with 0.01 M acetate. The rectilinear pCu range was 2 to 5.5. Recoveries of Cu2+ or ClO4- were 97% at 50 µM. The flow injection method was successfully applied to the determination of Cl- in seawater and urine. The electrodes could be used continuously for 2 weeks; the carbon rod could then be cleaned and re-coated. A flow-through anal. system that utilizes a membrane-coated carbon rod ion-selective electrode was investigated. Electrodes for Cu2+ based on a thiuram disulfide neutral carrier and for ClO4-, SCN-, NO3- and Cl- based on a bis(diphenylphosphino)propane-copper complex as ion exchanger exhibited satisfactory performance in a continuous-flow system. The response of the anion electrodes in a flow injection system was near Nernstian in the concentration. range 10^-2-10-4 or 10^-5M. Highly reproducible measurements were obtained with sample volumes of 30-100 µL and a sample injection rate of up to 400 h-1. The chloride electrode was suitable for the FIA determination of Cl- in seawater and urine.
Chloride Electrode Electrode Electrode Potentiometry Interferences Apparatus Detector

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

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

"Determination Of Copper In Seawater Using A Flow Injection Method With Chemiluminescence Detection"
Anal. Chim. Acta 1992 Volume 266, Issue 2 Pages 345-351
Kenneth H. Coale* and Kenneth S. Johnson, Paul M. Stout, Carole M. Sakamoto

Abstract: The method described by Yamada and Suzuki (cf. Anal. Lett., 1984, 17, 251) was modified to allow the shipboard determination of Cu in seawater. The modification involved pre-concentration. of the Cu on a column of quinolin-8-ol and use of the flow injection analysis manifold described previously (Anal. Chem., 1987, 59, 1789). The limit of detection was 0.4 mM and the time required was 8 min sample-1. The results on two reference standards showed good agreement with reported values. A method for dissolved Cu rapid determination in seawater is based on the formation of a complex between Cu and 1,10-phenanthroline and the subsequent chemiluminescence during the oxidation of the complex by H2O2. A flow injection manifold was constructed which provides for the separation of Cu from the seawater matrix with a column of immobilized 8-hydroxyquinoline. The column eluant was injected into a carrier stream, mixed with the reagents and delivered to a flow cell where emitted light was detected and used to quantify the amt. of Cu in the sample. The technique is noteworthy for its low detection limit (<0.4 nM), the rapidity of sample processing (~8 min/sample), the small sample volumes required (~4 mL), and the minimal precautions necessary for the prevention of sample contamination during shipboard processing.
Copper Chemiluminescence 8-Hydroxyquinoline Reference material Portable Complexation

"Evaluation Of Flow Injection Techniques For Microwave Plasma Torch Atomic-emission Spectrometry"
Anal. Chim. Acta 1993 Volume 277, Issue 1 Pages 1-8
Yolanda Madrid, Min Wu, Qinhan Jin and Gary M. Hieftje*

Abstract: Carrier solution, water, was pumped through an ultrasonic nebulizer to a microwave plasma torch (MPT; operating conditions tabulated). Sample containing Cu was pre-concentrated on a tapered micro-column (described) of C18-bonded silica and chelated with sodium diethyldithiocarbamate. After elution with ethanol the sample was drawn into a sample loop (75, 200, 250 or 500 µL); the carrier was directed through the sample loop, directing the sample into the MPT. The signal peak height obtained in flow injection (FI) mode (signal ~85% of that obtained with continuous nebulization) levelled off with a sample volume of 500 µL. The detection limit was 4.5 ng mL-1 with coefficient of variation of 1.8%; values were indistinguishable from results obtained with continuous sample injection. Copper in synthetic seawater was determined using the FI system. The pre-concentration. of the Cu prior to elution with ethanol eliminated errors due to Na+ and K+ present in a large number of natural matrices. The detection limit for Cu, following pre-concentration, was 0.16 ng mL-1 with coefficient of variation of ~3.2% at 500 ng mL-1 and recoveries of 94 to 97%.
Copper Spectrophotometry C18 Preconcentration Interferences

"Determination Of Picomolar Concentrations Of Titanium, Gallium And Indium In Seawater By Inductively Coupled Plasma Mass Spectrometry Following An 8-hydroxyquinoline Chelating Resin Preconcentration"
Anal. Chim. Acta 1993 Volume 282, Issue 1 Pages 63-74
Kristin J. Orians, Edward A. Boyle

Abstract: Seawater (4 l) was filtered through a polycarbonate membrane filter (0.4 µm), acidified to pH 1.5-2 with 6 M HCl, treated with 50-500 µL of 49Ti solution (50 ppb) and set aside for 2-24 h. The pH was adjusted to 4±0.3 with aqueous NH3 and the solution was pumped (4.5-5 ml/min) through a column (5 cm x 8 mm i.d.) containing 2 mL of quinolin-8-ol on a polymeric vinyl solid support. The column was washed with 3 mL of 0.02 M potassium hydrogen phthalate followed by 15 mL of water, and elution was effected with five 2 mL portions of 2.4 M HNO3. The eluate was split into two equal portions, one for direct analysis (Ti) and one for further concentration by evaporation (Ga and In, 3000-fold concentration). Analyses were performed by ICP-MS in the continuous-aspiration (0.8 ml/min) mass-scan mode (45.4-49.6 amu, Ti) or with use of FIA with a 300 µL sample loop in the peak-jump mode with standard additions (Ga and In). The detection limits for Ti, Ga and In were 0.2-0.4, 0.02 and 0.01 parts per 1012, respectively. The overall precision was 6-10% for concentrations greater than twice the detection limit and up to 20% for values near the detection limit.
Titanium Gallium Indium Mass spectrometry Spectrophotometry Chelation Preconcentration 8-Hydroxyquinoline Resin Isotope ratio Standard additions calibration

"Flow Injection And Continuous-flow Systems For The Determination Of Selenium(IV) And Selenium(VI) By Hydride-generation Atomic Absorption Spectrometry With Online Pre-reduction Of Selenium(VI) To Selenium(IV)"
Anal. Chim. Acta 1993 Volume 283, Issue 1 Pages 386-392
M. Gloria Cobo Fernandez, Maria A. Palacios and Carmen Camara*

Abstract: For the determination of Se(IV), sample solution was injected into or merged with a stream of 4 M HCl, which was then cooled and merged with cooled 0.5% NaBH4 solution in 4 M HCl in a knotted 30-cm coil. A stream of Ar (17.5 l/h) was used to transport the H2Se produced via a gas/liquid separator to a quartz cell for AAS measurement. To determine Se(IV) and Se(VI), sample stream, made 6 M in HCl, was injected into or merged with a stream of 12 M HCl, and passed through a 30-cm coil at 140°C. The stream was cooled before merging with a stream of 0.5% NaBH4 in 12 M HCl followed by the determination of the H2Se as before. all flow rates were 1.5 ml/min. Tolerance levels for a range of foreign ions are reported. Detection limits for Se(IV) without and with pre-reduction were 2 and 0.7 ng/ml, respectively, by the flow injection method and 1.5 ng/ml by the continuous-flow method; limits of detection for Se(VI) with pre-reduction were 0.7 and 1.5 ng/ml in the flow injection and continuous-flow mode, respectively. Response was linear for 125 ng/ml and the precision without and with pre-reduction was 2.5 and 3%, respectively, in flow injection mode and 2.1 and 5% in continuous-flow mode. The flow injection method was used to determine Se(IV) and Se(VI) added to seawater; recoveries were 99%.
Selenium(IV) Selenium(VI) Spectrophotometry Knotted reactor Phase separator Volatile generation Volatile generation

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

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

"Flow Injection Preconcentration Of Cobalt(II) On 1-nitroso-2-naphthol-3,6-disulfonate-modified Alumina For Flame Atomic Absorption Spectrometry"
Anal. Chim. Acta 1994 Volume 287, Issue 3 Pages 247-252
Marek Trojanowicz* and Krystyna Pyrzyska

Abstract: A solution of 5 mM disodium 1-nitroso-2-naphthol-3,6-disulfonate was pumped (3 ml/min) through a column (5 cm x 2.5 mm i.d.) of alumina (surface area 186 m2/g, average pore diameter 41 .angstrom.) to modify its surface. Samples were injected into a carrier stream of water which passed through the column for a pre-set time (typically 20 min) and flow rate (2.4-6 ml/min). The adsorbed Co(II) was eluted with 0.2 mL of 0.1 M NaOH at 2.7 ml/min and detected by AAS at 240.7 nm using an air/acetylene flame. For a flow rate of 2.4 ml/min and a 20 min pre-concentration time, the calibration graph was linear for up to 20 µg/l of Co(II), the detection limit was 0.44 µg/l and the RSD (n = 6) for 10 µg/l of Co(II) was 2.3%. Fe(III), Cu(II), Ni(II) and other metal ions did not interfere. The method was applied to oriental tobacco leaf reference material and the results agreed well with the certified values. The recovery of 1 µg/l of Co(II) from spiked artificial ocean water was 97% with a RSD of 3.3%.
Cobalt(II) Spectrophotometry Interferences Reference material Preconcentration

"Selective Flow Injection Sorbent-extraction For Determination Of Cadmium, Copper And Lead In Biological And Environmental Samples By Graphite-furnace Atomic Absorption Spectrometry"
Anal. Chim. Acta 1994 Volume 293, Issue 3 Pages 251-260
Renli Ma, Willy Van Mol and Freddy Adams*

Abstract: Biological material was heated with HNO3 to fuming, cooled, HClO4 was added, heated at 150°C for 8 h in a sealed bomb and the contents diluted for analysis. Geological material was digested with HF and HNO3 to fuming, digested as above, the bomb contents were evaporated to dryness and the residue dissolved in HNO3. Seawater of pH 1.5 and estuarine water of pH 2 were filtered. Samples were transferred to the FIA system, the stream (8.7 ml/min) was merged with an ammonium diethyldithiophosphate/0.1 M citric acid stream (2.2 ml/min; 0.01% for Cu, 0.1% for Pb and 0.2% or 0.5% for Cd in digests and seawater, respectively) and passed through the ODS sorbent extraction column (40-63 µm) for 20-80 s. After rinsing, elution was effected with ethanol at 5.7 ml/min for 2 s. The eluate was analyzed by GFAAS at 228.8, 324.8 and 283.3 nm and charring/atomization temperature of 400/1500, 1100/2500 and 1100/2300°C for Cd, Cu and Pb, respectively. Calibration graphs were linear up to 0.1, 5 and 4 µg/l with detection limits of 0.003, 0.05 and 0.04 µg/l of Cd, Cu and Pb, respectively. The recoveries for 25-50 ng/l of Cd, 0.5-1 µg/l of Cu and 50 ng/l of Pb from sea and estuarine waters were >87.6%.
Cadmium Copper Lead Spectrophotometry Sample preparation Solid phase extraction

"Determination Of Hydrogen Peroxide In Seawater By Flow Injection Analysis With Chemiluminescence Detection"
Anal. Chim. Acta 1994 Volume 298, Issue 1 Pages 121-128
David Pricea, Paul J. Worsfolda,*, R. Fauzi and C. Mantourab

Abstract: Hydrogen peroxide (H2O2) plays a key role in many marine chemical processes, e.g., redox reactions involving transition metals and organic compounds. A rapid, flow-injection procedure with chemiluminescence detection for the determination of H2O2 in sea water is reported. It is based on the H2O2 induced oxidation of an alkaline solution of luminol in the presence of a catalyst (cobalt(II)). The sample throughput was 120 h-1 with small sample volumes (100 µL) and low detection limits (10 nM in Milli-Q water; 5 nM in sea water, S/N = 3). The working linear range, which is suitable for the determination of ambient levels of H2O2 in sea water was 5-500 nM. A portable, automated version of the monitor has been successfully deployed onboard ship in the western Mediterranean and a typical depth profile for H2O2 is presented.
Hydrogen peroxide Chemiluminescence

"Turbidimetric Determination Of Sulfate In Waters Employing Flow Injection And Lead Sulfate Formation"
Anal. Chim. Acta 1995 Volume 300, Issue 1-3 Pages 149-153
Ricardo Erthal Santelli*, Paulo Roberto Salgado Lopes, Regina C&eacute;lia Leme Santelli and Angela De Luca Rebello Wagener

Abstract: A 1.3 mL water sample was injected into a carrier stream of 1 mM HNO3 in ethanol/H2O (1:1) at a flow rate of 0.92 ml/min and the mixture was merged with a reagent solution (0.17 ml/min) comprising 1.9% lead nitrate and 1% poly(vinyl alcohol) in ethanol/H2O (1:1). An auxiliary stream (0.03 ml/min) containing 100 µg/ml of sulfate was merged with the sample plug before it entered a 100 cm x 0.5 mm i.d. precipitation coil at 61°C. After reaction, the absorbance was measured at 410 nm. Interference from chloride was eliminated by maintaining the coil at >55°C. The calibration graph was linear in the range 2-20 µg/ml of sulfate, the detection limit was 0.3 µg/ml and the RSD for 2 µg/ml of sulfate was 3% (n = 11). The analytical throughput was 35 samples/h. The method was applied to the determination of sulfate in fresh and saline waters.
Sulfate Turbidimetry Interferences Heated reaction Precipitation

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

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

"Characterization And Reduction Of Interferences In Flow Injection Analysis For The In Situ Determination Of Nitrate And Nitrite In Seawater"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 413-424
Anne Daniel, a, Dominique Birot*, Michel Lehaitre and Jacques Poncin

Abstract: An FIA method for the in situ determination of nitrate and nitrite in seawater was studied in order to improve the precision and sensitivity. The method was based on the reduction of nitrate to nitrite using a Cd column and the spectrophotometric detection of nitrite following reaction with an azo dye. The Cd reduction column could be switched in and out of the line to allow the determination of nitrite and total nitrate/nitrite concentrations. The sample stream (1.4 ml/min) was merged with a 30 g/l ammonium chloride buffer stream of pH 8.5. After passing through the reduction column, the flow was split into two equal streams of 1.2 ml/min each. These streams were merged with streams (0.6 ml/min) of 10 g/l sulfanilamide in 10% HCl or 1 g/l N-(1-naphthyl)ethylenediamine. The streams were recombined before passing through the reaction coil to the detection cell where the absorbance at 540 nm was measured against a background at 630 nm. The calibration graph was linear for up to 40 µM-nitrate and the detection limit was 0.45 µM. The RSD (n = 6) for the determination of 0.5 µM-nitrate were ~e;5%. The effects of pressure, salinity and temperature on the determination were studied.
Nitrate Nitrite Spectrophotometry Interferences Reduction column Optimization Refractive index Sample splitting

"Iron(II) And Iron(III) Determination In Seawater At The Nanomolar Level With Selective Online Preconcentration And Spectrophotometric Determination"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 425-432
S. Blain* and P. Tr&eacute;guer

Abstract: An FIA method which included online filtration, acidification, reduction, pre-concentration and spectrophotometric detection is described for the shipboard determination of Fe(II) and Fe(III) in seawater. The pre-concentration was carried out using a C18-phase column impregnated with ferrozine, a selective reagent for Fe(II). Fe(III) was determined following reduction to Fe(II) with ascorbic acid. The analysis was performed by propelling a filtered mixture of seawater/2.5 M acetate buffer of pH 4.5 (25:1) through the pre-concentration column at 2 ml/min for 2-20 min. The pre-concentration column was rinsed with 0.7 M NaCl for 2 min at 2 ml/min. The retained Fe(II)-ferrozine complex was eluted with methanol at 0.42 ml/min. The resulting stream was diluted by merging with a methanol/H2O stream (4:1; 0.32 ml/min) prior to measuring the absorbance at 280 nm. Ascorbic acid (100 µM) was added to the acetate buffer to reduce Fe(III). The calibration graphs for Fe(II) and Fe(III) were linear up to 75 and 200 mM, respectively, with a sampling period of 2 min. The detection limit was 0.1 nM-Fe(II) was with a 20 min sampling period. The accuracy of the method was verified by determining Fe(II) in a certified reference seawater containing 1.87±0.28 nM-Fe(III).
Iron(2+) Iron(III) Spectrophotometry Speciation Reference material Preconcentration C18

"Shipboard Flow Injection Determination Of Seawater PH With Spectrophotometric Detection"
Anal. Chim. Acta 1995 Volume 309, Issue 1-3 Pages 259-270
Richard G. J. Bellerby, David R. Turner, Geoffrey E. Millward and Paul J. Worsfold

Abstract: Seawater was pumped at 12 ml/min through a flow-cell, and using stopped-flow analysis a zero reading was obtained for 30 s at 433 nm and 558 nm. After flow-restart, ~8.3 µL of an 0.8-0.9 absorbance (at 558 nm) solution of phenol red indicator (Na salt) in seawater was added and the solutions mixed in a 1 m reaction coil. The flow was again stopped, and after a 30 s delay, the absorbances at 433 nm and 558 nm were obtained. Over the range 18-27°C an error of ±0.001 pH/°C was estimated. Sample alkalinities were calculated from pCO2 and total CO2 parameters obtained via carbonic acid dissociation constants (details given), the data demonstrating internal consistency with sample pH. Over a 3 h period, a weighted standard deviation of ±0.005 pH units was obtained (n = 106) with associated precisions of ±2 µatm of pCO2 and ±1 µmol total CO2/kg, respectively. No method calibration was necessary.
pH Spectrophotometry Calibration Equilibrium constants Portable Stopped-flow

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

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

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

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

"Analysis Of Ammonia And Methylamines In Natural-waters By Flow Injection Gas Diffusion Coupled To Ion Chromatography"
Anal. Chim. Acta 1995 Volume 316, Issue 3 Pages 291-304
Stuart W. Gibb, R. Fauzi C. Mantoura and Peter S. Liss

Abstract: Flow injection gas diffusion-ion chromatography (FIGD-IC), is a new hyphenated technique for the simultaneous analysis of nanomolar levels of ammonia (NH3) and methylamines (MAs) in < 50 mi of marine, estuarine and freshwaters. Alkaline EDTA is added online to flowing sample to achieve a sufficiently high pH (> 12.0) needed to deprotonate > 95% of the amines to their uncharged volatile forms. In addition the reagent chelates Mg2+ and Ca2+ to prevent their precipitation as Ca(OH)(2) and Mg(OH)(2). The amines diffuse selectively across a gas-permeable microporous PTFE Goretex(R) membrane into a recirculating flow of acidic 'acceptor' in which they are reprotonated and pre-concentrated. The acceptor solution is then injected onto an ion chromatograph (IC) where NH4+ and MA cations are separated within 15 min and detected by chemically suppressed conductimetry using cyclopropylamine as an internal standard for quantification. The response of the coupled FIGD-IC system was sensitive (ca. 3-5 nM for MAs, 20-40 nM for NH3), linear (r2 = 0.99, 0-2000 nM in seawater) and precise (RSD = 1-6% at 1 µM) for all analytes. The applicability of FIGD-IC is demonstrated through laboratory analysis of NH3 and MAs in a range of natural water samples, on-board a research vessel, and through inter-comparisons with fluorimetric assay of NH3. (40 References)
Amines, methyl Ammonia HPIC Conductometry Gas diffusion Goretex Internal standard Preconcentration Simultaneous analysis

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

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

"Model Compounds For The Determination Of Organic And Total Phosphorus Dissolved In Natural Waters"
Anal. Chim. Acta 1996 Volume 318, Issue 3 Pages 385-390
Roger K&eacute;rouel and Alain Aminot*

Abstract: Methods for the determination of organic and total P in natural waters based on the hydrolysis and oxidation of all complexed forms of P to phosphate by acidic and alkaline persulfate oxidation, continuous-flow UV irradiation and high temperature combustion (HTC) were studied. Ten compounds were used to test the efficiency of these hydrolysis/oxidation reactions. The results indicated that in such methods, recoveries should be tested using model compounds with HTC as the reference method. One labile compound (phosphoenolpyruvate, glycerophosphate or riboflavin-5-phosphate) and one refractory compound (aminoethylphosphonic acid, phytic acid or phosphorylcholine) should be used to determine an upper and lower recovery, respectively. The recoveries depended on the matrix; quantitative recoveries were obtained with fresh water but not with seawater. For the determination of P in seawater the alkaline persulfate oxidation method is recommended.
Phosphorus

"Determination Of Trimethylamine Oxide In Seawater And Small Volumes Of Seafood Tissue Extract Using Flow Injection Analysis"
Anal. Chim. Acta 1996 Volume 334, Issue 3 Pages 279-285
Saloua Sadok, Roger F. Uglow and Stephen J. Haswell*

Abstract: The supernatant of homogenized and centrifuged seafood (1 ml) was treated with 20 µL of 15% TiCl3 solution to reduce trimethylamine oxide to trimethylamine, and a 100 µL portion was injected directly into a FIA system in which it was mixed with 12% formaldehyde solution followed by 0.6 M NaOH and 0.03% bromothymol blue solution (all at 1 ml/min) and passed through a gas-permeable membrane, with detection at 635 nm. A second sample portion was analyzed without reduction to determine the original trimethylamine, and the difference in peak heights gave the amount of oxide present. Seawater was also analyzed with use of a 300 µL volume loop and 0.35 M NaOH. Linear calibration graphs for six standards in 6% HClO4 were obtained in the range 10^-200 µM, with RSD (n = 10) of ?. The detection limit was 6 µM-trimethylamine oxide. The corresponding values in seawater were 10^-100 µM and 2.5 µM.
Trimethylamine oxide Spectrophotometry Sample preparation

"A Flow Cell For Online Monitoring Of Metals In Natural Waters By Voltammetry With A Mercury Drop Electrode"
Anal. Chim. Acta 1997 Volume 346, Issue 1 Pages 101-111
Carlo Colombo, Constant M. G. van den Berg*, and Anne Daniel

Abstract: A flow-through detection cell is described for determining trace metals in nonpolluted seawater by cathodic-stripping voltammetry. The cell was constructed from cylindrical extruded acrylic drilled to give a flow channel of 1 cm x 0.7 mm (4 µL volume) and equipped with a hanging Hg drop electrode (0.46 mm i.d., 0.67 mm2), a Ag/AgCl reference electrode and a Pt wire auxiliary electrode. The detection cell was incorporated into a computer-controlled voltammetric system with a tangential flow filter, online UV digestion to destroy organic matter, a three-way switching value for the addition of reagents and standards and online deoxygenation. Filtered, UV-digested seawater (0.8 ml/min) merged with a reagent stream (0.135 ml/min) to produce a measurement solution containing 0.45 M NaNO2, 25 mM NH3/NH4Cl and 4.5 µM-1,2-cyclohexanedione dioxime (nioxine) of pH 9. After deoxygenation, the voltammetric measurement was performed with an accumulation potential of -0.75 V for 30 s, a 5 s equilibration period and a stepped potential scan to -1.25 V. A linear response was obtained for up to 550 pM-Co, the detection limit was 5.4 pM and the RSD for 29.6 pM-Co was 6%. The analysis rate was 40-60 samples/h. The method was verified by analyzing certified seawater.
Cobalt Voltammetry Electrode Sample preparation Reference material UV reactor Detector Flowcell Photochemistry

"Behaviour Of Matrix Cations During Online Preconcentration And Atomic Spectrometric Detection Of Trace Metals In Natural Waters"
Anal. Chim. Acta 1997 Volume 351, Issue 1-3 Pages 311-317
Robert A. Nickson, Steve J. Hill and Paul J. Worsfold*

Abstract: A flow injection procedure with detection by inductively coupled plasma-mass spectrometry (ICP-MS) for the on-line matrix elimination and pre-concentration of five elements (Cd, Co, Cu, Mn and Pb) from natural waters on a commercially available iminodiacetic acid resin is described. The results for the certified reference materials (CRMs) NASS-2 (an open ocean seawater) and SLRS-2 (a river water) gave good agreement with certified values. Recoveries from seawater were in the range 95-111% with relative standard deviations (RSDs) (n = 5) in the range 5-8%. The efficiency with which the major matrix cations (Ca2+, K+, Mg2+ and Na+) were removed has also been investigated and the importance of using suitable buffers and concentrations for the efficient removal of all of these cations with minimal reagent contamination is highlighted. The application of this column system for in-situ pre-concentration is also discussed (with pre-concentration factors of up to 120X) and Mn (selected as a model element) has also been quantified in SLRS-2 by flow injection-flume atomic absorption spectrometry (FI-FAAS) using 15 min pre-concentration. This shows that the method can be used effectively with both flame and plasma detection.
Metals, trace Mass spectrometry 8-Hydroxyquinoline Preconcentration Interferences

"Determination Of Sub-nanomolar Levels Of Iron In Seawater Using Flow Injection With Chemiluminescence Detection"
Anal. Chim. Acta 1998 Volume 361, Issue 3 Pages 189-200
Andrew R. Bowiea, b, Eric P. Achterberga, R. Fauzi C. Mantourab and Paul J. Worsfolda,*

Abstract: A highly sensitive system for the shipboard determination of dissolved Fe at the sub-nM level is based on a flow injection method coupled with luminol chemiluminescence detection. Dissolved Fe(II+III) levels are determined after Fe(III) reduction using sulfite and inline matrix elimination/pre-concentration on an 8-hydroxyquinoline (8-quinolinol) chelating resin column. The detection limit (3s) is 40 pM when 1.5 mL of sample is loaded onto the column, and the relative standard deviation is 3.2% (n=5) for a 1.0 nM Fe sample. One analysis cycle can be completed in 3 min. The automated method proved reliable when used on-board the RRS James Clark Ross during Autumn 1996, mapping dissolvable Fe(II+III) levels along the Atlantic Meridional Transect from 50°N to 50°S. Data from vertical profiles through the upper water column are presented.
Iron Chemiluminescence Preconcentration 8-Hydroxyquinoline Resin Remote instrument

"A Submersible Flow Injection-based Sensor For The Determination Of Total Oxidized Nitrogen In Coastal Waters"
Anal. Chim. Acta 1998 Volume 361, Issue 1-2 Pages 63-72
Anthony R. J. Davida, Trevor McCormacka, Alan W. Morrisb and Paul J. Worsfolda,*

Abstract: The design and construction of a remotely deployed submersible sensor for the determination of total oxidized nitrogen (nitrate plus nitrite) in seawater is described. It was based on the flow injection principle, with solid state spectrophotometric detection of the diazotization product from the reaction of nitrite with N-(1-naphthyl)ethylenediamine dihydrochloride (N1NED) and sulfanilamide. Nitrate was pre-reduced inline with a copperized cadmium powder column. The limit of detection (3 s) was 0.1 µM nitrate (1.4 µg N/L) and the linear range was 0.1-55 µM nitrate with a 20 mm path length flow cell and a 260 µL sample loop. The linear range was modified for different environmental conditions by changing the sample loop size and(or) the flow cell path length. Results are presented for preliminary lab. studies and field trials in the Tamar Estuary and for deployments in the North Sea. The sensor was successfully deployed on three sep. occasions for complete tidal cycles (13 h) at a depth of 4 m from the bow of the RRS Challenger. Field data are compared with results from a shipboard air segmented analyzer and correlated with turbidity and salinity data.
Nitrogen, total, oxidized Spectrophotometry Remote instrument Reduction column Method comparison

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

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

"Direct Trace Determination Of Lead In Estuarine Water Using In-situ Preconcentration Of Lead Hydride On Ir, Zr And W-coated Graphite Tubes"
Anal. Chim. Acta 1998 Volume 368, Issue 3 Pages 281-289
Pilar Bermejo-Barrera*, Jorge Moreda-Pi&ntilde;eiro, Antonio Moreda-Pi&ntilde;eiro and Adela Bermejo-Barrera

Abstract: Methods for the direct trace determination of lead in sea water involving hydride generation, trapping and the atomization of the hydride generated in a graphite furnace has been developed. Different permanent coated graphite tubes: iridium, tungstate and zirconium coated graphite tubes were investigated for the in situ pre-concentration of lead hydride. The results obtained were compared with the ones achieved by the conventional HG-AAS. Trapping on Ir-coated graphite tubes offers the best analytical performances, with detection limits of 60 ng 1-1. The accuracy was studied using IAEA/W-4 and SLRS-2 reference materials, and the method was applied to several sea water samples. The number of samples analyzed in an hour was 40. 41 References.
Lead Spectrophotometry Volatile generation Reference material

"Speciative Determination Of Chromium(VI) And Chromium(III) Using Flow Injection Online Preconcentration And Flame Atomic-absorption Spectrometric Detection"
Anal. Chim. Acta 1998 Volume 369, Issue 1-2 Pages 69-77
T. Prasada Rao*, S. Karthikeyan, B. Vijayalekshmy and C. S. P. Iyer

Abstract: A rapid, sensitive and selective method for the speciative determination of Cr(VI) and Cr(III) in sea-water samples by flame atomic-absorption spectrometry, using online pre-concentration. on a micro-column packed with C18 bonded silica gel, was developed. This is based on the selective formation of diethyldithiocarbamate complexes of Cr(VI) in the 1-2 pH range and Cr(III) in the 4-9 pH range in the presence of Mn(II) (which enhances the Cr(III) signal 10-fold). The pre-concentrated species desorbed by MeOH directly from the column to the nebulizer-burner system using a flow rate of 4.0 mL/min. Five hundred-fold enrichment of Cr(VI) and Cr(III) was observed with a detection limit of 0.02 µg/l for a 5 min pre-concentration. time. The effect of probable concomitant species in seawater was determined and a satisfactory recovery of 95-105% could be obtained. Linear calibration curves were obtained for both the species, Cr(VI) and Cr(III), in the 0.2-200 µg/l concentration. range. Relative standard deviations were 3.5 and 5.1% for Cr(VI) and Cr(III), respectively, in the determination of 50 µg/l of each of these species. The developed procedure is suitable for the determination of Cr(VI) and Cr(III) species (Cr(total)) in various sea-water samples of western and eastern coasts of India. Further, the developed procedure was successfully applied for the determination of Cr(VI) and Cr(III) species in tannery and plating-bath effluents.
Chromium(III) Chromium(VI) Spectrophotometry Speciation Preconcentration C18 Silica Diethyldithiocarbamate Complexation

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

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

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

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

"Use Of 4-(2-pyridylazo)resorcinol Or 2-(2-pyridylazo)-5-dimethylaminophenol As Chelating Agent For Determination Of Cadmium In Seawater By Atomic Absorption Spectrometry With Online Flow Injection Sorbent Extraction"
Anal. Chim. Acta 1998 Volume 376, Issue 3 Pages 305-311
Pi-Guey Su and Shang-Da Huang*

Abstract: A home-made automatic online flow injection sorbent extraction system for graphite furnace atomic absorption spectrometry (GFAAS) was used to determine Cd in seawater using octadecyl functional group (C18) bonded silica gel as sorbent, 4-(2-pyridylazo)resorcinol (PAR) or 2-(2-pyridylazo)-5-dimethylaminophenol (PADMAP) as chelating agent and methanol as eluent. The range of pH for the determination of Cd in seawater was 4.7-7.4 and 7.1-9.0 for using PAR and PADMAP as chelating agents, respectively. For the long-term stability studies, (PAR-Cd or PADMAP-Cd) are stable within the pH range 4.7-7.4 (for PAR) or 7.1-9.0 (for PADMAP) for 1 h at least. Sample volume of only 500-1000 µL was required to determine Cd in seawater. The simple calibration curve method was used and the detection limits of the determination of Cd in seawater were 4.0 and 1.7 ng L-1 for PAR and PADMAP as chelating agents, respectively. The sample throughput is 9-12 h-1. The accuracy and precision of the method were confirmed by the anal. of three kinds of certifie reference saline water.
Cadmium Spectrophotometry Preconcentration Reference material C18 Chelation pH

"In Situ Determination Of Silicic Acid In Sea Water Based On FIA And Colorimetric Dual-wavelength Measurements."
Anal. Chim. Acta 1998 Volume 377, Issue 2-3 Pages 157-166
Julien Floch, St&eacute;phane Blain*, Dominique Birot and Paul Treguer

Abstract: A method has been developed to determine silicic acid in sea water with submersible chemical analyzer. It is based on direct FIA, for fast and discrete measurements, and dual wavelength treatment of the signal to correct the refractive index interference, the main factor that affects in situ anal. Fast anal. rate (60 discrete samples per h) is achieved because of a very short lag time between sampling and injection of the sample into the carrier stream. This allow high resoln. in situ measurements, giving access to small scale transitory processes concerning nutrients cycles in ocean ecosystem. This colorimetric method is based on the formation of beta silicomolybdic acid reduced in intense colored molybdenum blue. Rapid and non temperature dependent reduction is obtained by using tin(II) chloride as reductor. There is little interference from phosphate in the usual conditions at sea. For in situ applications, we gave special attention to the effect of temperature (0-30°C) and salinity (0-34) variations that can greatly influence the silicomolybdate complex formation. This reaction zone has to be thermostated and kept above 20°C. A max. signal enhancement of 12% is encountered when samples salinity varies from 34 to 0 (PSS78), but no significant deviations are observed between 34 and 28 (PSS78). The precision of the method is 1% for silicate concentrations. above 5 µM and the limit of detection is 0.3 µM. The comparison of the measurements obtained by this method and the usual flow sequential anal. system showed good agreement. The method has been implemented on an in situ chemical analyzer and simultaneous silicic acid and nitrate concentration. measurements were carried out in coastal waters.
Silicic acid Nitrate Spectrophotometry Remote instrument Dual detection Interferences Simultaneous analysis Manifold comparison

"Determination Of Cadmium In Seawater Using Automated Online Preconcentration And Direct Injection Graphite Furnace Atomic Absorption Spectrometry"
Anal. Chim. Acta 1998 Volume 377, Issue 2-3 Pages 255-262
D. Colbert, K. S. Johnson and K. H. Coalea

Abstract: An online pre-concentration method for the determination of cadmium in seawater was developed for graphite furnace atomic absorption spectrometry (GFAAS) using deuterium lamp background correction. The technique was adapted from a previously reported technique and was fully automated. Automated pre-concentration of cadmium reduced the concentrations of matrix elements in samples to levels that did not interfere with the determination of cadmium at ultratrace levels. The soluble ligand, 1-pyrrolidinecarbodithioic acid (APDC), was mixed with the sample in a continuous-flow system to form a nonpolar metal complex which was absorbed onto a C18 column. The metal complex was then eluted from the column directly into the graphite furnace. The addition of an inline nitric acid rinse step between sample load cycles allowed for the determination of cadmium with one elute cycle. Other modifications included lab. purifn. of the ammonium acetate rinse solution, a nonbuffered APDC ligand solution, and a computer-activated load cycle to reduce sample consumption. The average column recovery was 73% with a sample loading flow rate of 2.2 mL/min and 55 s pre-concentration time. Sample throughput was ~15 samples/h with 2 mL of sample pre-concentrated and analyzed every 4 min. The small sample volume required made this method useful where sample volumes are limited. The 3s limit of detection for replicate blanks was 42 pM Cd (n = 5) for a 2 mL sample. The effectiveness of the method was demonstrated for the determination of Cd in certified open ocean reference materials NASS-3 and NASS-4. Analysis of Cd in equatorial Pacific seawater demonstrated that the system produces oceanographically consistent results.
Cadmium Spectrophotometry Preconcentration Reference material C18 APDC

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

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

"Determination Of Copper Complexation In Seawater Using Flow Injection Analysis With Chemiluminescence Detection"
Anal. Chim. Acta 1998 Volume 377, Issue 2-3 Pages 133-144
Heidi Zamzow, Kenneth H. Coale, Kenneth S. Johnson, and Carole M. Sakamoto

Abstract: Flow injection analysis with chemiluminescence detection (FIA-CL) via the reaction of copper with 1,10-phenanthroline was used for the determination of copper complexation in seawater. A detection limit of 0.1 nM Cu in undiluted seawater without sample pre-concentration was obtained. Copper speciation was assessed by titrating natural seawater ligands with added copper. This method was used to measure copper complexation throughout the water column in Monterey Bay, California. Two ligand classes were identified: a strong ligand (L1), ranging in concentration. from 1.3 to 3.1 nM, and a weaker ligand (L2), ranging from 9.4 to 25.6 nM. The average conditional stability constant for the strong ligand was log K1' 13.1±0.4 and for the weaker ligand log K2' 9.4±0.6. These measurements are in good agreement with complexation studies previously performed using established methods. This technique may eventually be adapted for in situ complexation measurements that can be used to monitor natural spatial and temporal variations in copper complexation, as well as coastal ecosystem responses to urban and industrial change.
Copper, labile Chemiluminescence Voltammetry Complexation Speciation

"Dissolved Iron At Subnanomolar Levels In The Southern Ocean As Determined By Ship-board Analysis"
Anal. Chim. Acta 1998 Volume 377, Issue 2-3 Pages 113-124
J. T. M. de Jong*, J. den Das, U. Bathmann, M. H. C. Stoll, G. Kattner, R. F. Nolting and H. J. W. de Baar

Abstract: The biogeochem. of iron was investigated in remote waters of the Antarctic ocean in the austral summer of 1995/1996.A sensitive flow injection analyzer, based on inline pre-concentration and luminol chemiluminescence detection (FIA-CL), was used for underway surface measurements and vertical profiling during a fine scale survey in the Polar Front (PF) in the Atlantic sector of the Southern Ocean. Results indicated a dynamic environment with dissolved iron concentrations ranging from 0.05 to 0.3 nM. Distributions are consistent with chlorophyll a and fCO2 suggesting a coupling with these parameters. The highest iron concentrations (0.3 nM) were found where chlorophyll a abundance was highest and CO2 undersatn. the most pronounced. The vertical distribution (upper 500 m) revealed a nutrient type distribution with low subsurface values (0.1 nM) gradually increasing to ~0.3 nM at depth.
Iron Chemiluminescence Preconcentration Remote instrument

"Rapid Determination Of Manganese In Seawater By Flow Injection Analysis With Chemiluminescence Detection"
Anal. Chim. Acta 1991 Volume 249, Issue 2 Pages 469-478
Thomas P. Chapin, Kenneth S. Johnson and Kenneth H. Coale

Abstract: The manganese was concentrated on a column of 8-hydroxyquinoline immobilized on Fractogel and was eluted with 0.0025 M HCl. The eluate at 2.7 mL min-1 was mixed with a reagent containing 0.25 mM 7,7,8,8-tetracyanoquinodimethane (I), 0.30 mM 2',4',5,7'-tetrabromofluorescein and 4 mM didodecylmethylammonium bromide and with 0.01 M NaOH, both at 1.3 mL min-1. The luminescence caused by the oxidation of I and catalyzed by Mn(II) was measured by a photomultiplier. The calibration graph was rectilinear from 1 to 100 mM, with a detection limit of 0.1 nM. In the analysis of standard sea-waters the results agreed closely with certified values and gave standard deviations (n = 3 and 4) of 2.8 and 0.07 for ~43 and 0.48 nM, respectively.
Manganese Chemiluminescence Catalysis Column Reference material 8-Hydroxyquinoline

"In-line Deoxygenation For Flow Analysis With Voltammetric Detection"
Anal. Chim. Acta 1998 Volume 377, Issue 2-3 Pages 229-240
Carlo Colombo and Constant M. G. van den Berg*

Abstract: Voltammetric detection of metals in natural waters suffers from interference by dissolved oxygen. We describe here a deoxygenation method suitable for flow analysis with detection by cathodic stripping voltammetry (FIA-CSV). The apparatus is based on the permeation of oxygen through semi-permeable tubing (silicone, Poreflon and others) into an oxygen-free chamber. Two methods of oxygen removal are proposed: in the first oxygen is removed physically from the chamber by flushing with nitrogen at a rate of 50 mL min-1; in the second oxygen is removed chemically by filling the chamber with an aqueous solution of a reducing agent (Na2SO3 or other compounds). At a fixed sample flow rate of 1 mL min-1, the length of the tubing is the main parameter which affects the deoxygenation efficiency, as it determines the residence time of the sample. 98% oxygen removal is achieved using 3 m tubing (36s residence time). A removal of 90% of oxygen (1 m tubing and 12 s residence time) is sufficient to obtain a background current similar to conventional (batch) voltammetric systems and reproducible metal (copper and cobalt) peak heights are obtained at low metal concentrations. This enables the determination of trace metals by flow analysis with voltammetric detection at concentration levels encountered in uncontaminated seawater.
Copper Cobalt Voltammetry Silicone membrane

"Sensitive Flow-Injection Amperometric Detection Of Iodide Using Mn3+ And As3+"
Anal. Sci. 2005 Volume 21, Issue 5 Pages 525-529
Snezana D. NIKOLIC, Jelena J. MUTIC, Aleksandar D. LOLIC, and Dragan D. MANOJLOVIC

Abstract: A rapid, selective, and sensitive kinetic flow-injection method for iodide content determination with amperometric detection on a platinum electrode was developed. The method is based on the catalytic effect of iodide on the Mn3+ reaction with As3+ in the presence of sulfuric acid. The calibration curve was linear in the concentration range from 5.0 x 10^-7 to 1.0 x 10^-4 mol/L iodide. The limit of detection (LOD) was found to be 5.0 x 10^-9 mol/L iodide. The relative standard deviations (RSD) were 1.68% and 3.03% for 1.0 x 10^-3 mol/L standard and 1.0 x 10^-6 mol/L iodide solution (n = 6), respectively. The method has been successfully applied for determination of iodide in waters, table salts, fodder, organic substances and human blood sera. The results were compared with those obtained by a standard AOAC (Association of Official Analytical Chemists) method, as well as with those obtained by a kinetic spectrophotometric procedure for determination of iodide.
Iodide Amperometry Electrode Method comparison Interferences Catalysis

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

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

"Determination Of Ultratrace Amounts Of Cobalt By Catalysis Of The Tiron-hydrogen Peroxide Reaction With An Improved Continuous-flow Analysis System"
Talanta 1987 Volume 34, Issue 2 Pages 277-281
Kenji Isshiki, Eiichiro Nakayama

Abstract: A schematic diagram is given of the continuous-flow system in which air segmentation is introduced after mixing of the reactants, which were samples in 0.1 M HCl, 0.05 M Na2CO3 - NaHCO3 in 0.1 M NaOH, 0.01 M tiron and 5 mM H2O2. Optimum conditions were a reaction time of 210 s, a temperature of 30°C, pH 11.2, and absorbance measurement at 440 nm. From 3 to 5000 pg of Co(II) can be determined in 1 mL of acidified sample, at a rate of 40 samples h-1. The coefficient of variation (n = 10) were 1 and 3% for 100 and 10 pg mL-1 of Co, respectively. A considerable number of species interfere when present in 100-fold amounts relative to Co and must be removed before determination. Results are given for the determination of Co in seawater.
Cobalt Spectrophotometry Air segmentation Catalysis Heated reaction Interferences Optimization Tiron Ultratrace

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

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

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

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

"HPLC Coupled With Inline Photolysis, Hydride Generation And Flame Atomic Absorption Spectrometry For The Speciation Of Tin In Natural Waters"
Talanta 1991 Volume 38, Issue 6 Pages 607-611
Les Ebdon, Steve J. Hill and Philip Jones

Abstract: Tin species were separated by HPLC on a column (25 cm x 4.6 mm) of Partisil 10-SCX (10 µm) with methanol - 0.1 M ammonium acetate (4:1) as mobile phase. Tributylin in the eluate was converted to Sn(IV) by decomposition with UV irradiation before passing to a continuous-flow hydride generator (cf. Anal. Chim. Acta., 1982, 136, 191) and the hydrides produced in the presence of 1% of NaBH4 in 0.1 M NaOH and 0.2 M HCl were carried, under N, to a flame atomic absorption spectrometer for analysis. The detection limit was 2 ng of Sn; analysis time was 6 min. The method was applied in the analysis of seawater.
Tin HPLC Spectrophotometry UV reactor Volatile generation Speciation Volatile generation Photochemistry

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

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

"Online Flow Injection Analysis Of Volatile Organic Compounds In Seawater By Membrane Introduction Mass Spectrometry"
Talanta 1995 Volume 42, Issue 9 Pages 1325-1334
N. Kasthurikrishnan and R. G. Cooks*,

Abstract: FIA with membrane introduction MS for the determination of volatile organic compounds (VOC) in seawater was examined and was compared to measurements made in water. MS was performed using a benchtop ion-trap mass spectrometer and characterization of various aspects of the flow injection and ion-trap combination was carried out. The analyte responses were linear over several orders of magnitude (e.g. for methylene chloride), independent of seawater pH (e.g. for chlorobenzene) and independent of matrix effects for the VOC studied. A comparison of the performance of a microporous (Teflon) membrane was made, and the former provided lower detection limits which were in the parts-per-trillion range. The microporous membrane provided faster response times by a factor of four to five for relatively more polar compounds.
Organic compounds, volatile Mass spectrometry Mass spectrometry Teflon membrane PPT

"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

"Polarographic Study Of Acrolein And Its Determination By Flow Injection With Amperometric Detection At A Mercury Electrode"
Talanta 1996 Volume 43, Issue 7 Pages 1117-1124
Ignacio Naranjo Rodr&iacute;guez, Juan A. Mu&ntilde;oz Leyva and Jos&eacute; L. Hidalgo Hidalgo de Cisneros*

Abstract: The electrochemical behavior of acrolein (acrylaldehyde) was studied using direct current tast and differential pulse polarography. Three drop sizes of mercury at a dropping mercury electrode were also investigated. The studies were performed in Britton-Robinson buffer of pH 10 with a drop time of 1 s, a scan rate of 4 mV/s and a potential range of -1.1 to -1.5 V. A FIA method is proposed for the polarographic determination of acrylaldehyde with linear calibration graphs from 0.1-1 µM and 1-10 µM and a detection limit of 98 nM. The RSD (n = 11) was 2.9% for 0.2 µM. Acrylaldehyde was determined in seawater by injecting sample containing 0.25 mM EDTA into a carrier stream (1.8 ml/min) of Britton-Robinson buffer of pH 10 and polarographic detection at -1.4 V using a fresh hanging-Hg-drop electrode. Recoveries were 96-105%.
Acrolein Polarography Amperometry Electrode Buffer

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

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

"Immobilization Of 8-hydroxyquinoline Onto Silicone Tubing For The Determination Of Trace Elements In Seawater Using Flow Injection ICP-MS"
Talanta 1998 Volume 47, Issue 2 Pages 439-445
S. N. Willie*, H. Tekgul and R. E. Sturgeon

Abstract: A rapid and simple online method is described for the pre-concentration of Mn, Co, Ni, Cu, Zn, Cd and Pb from seawater using 8-hydroxyquinoline immobilized onto silicone tubing (Sil-8-HQ) via the Mannich reaction. Recoveries 35-95% and limits of detection in the ppt range were obtained using a 2 m long Sil-8-HQ tube with a sample flow rate of 1.0 mL/min. A tube could be subjected to sample loading and elution cycles over 200 times. The capacity was 1.5 and 1.3 µg/cm2 for Cu and Mn, respectively. Cu, Cd, Co, Pb, Mn, Zn and Ni were determined in coastal and open ocean seawater using flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS). Good agreement with certified values for the certified reference materials NASS-4 and CASS-3 was demonstrated when quantitation was undertaken by the method of additions
Manganese Cobalt Nickel Copper Zinc Cadmium Lead Mass spectrometry Tube wall immobilization Silicone tubing 8-Hydroxyquinoline Preconcentration Reference material Standard additions calibration

"Kinetic-catalytic Determination Of Traces Of Iron By The Oxidative Coupling Reaction Of 3-methyl-2-benzothiazolinone Hydrazone With N,N-dimethylaniline"
Talanta 1998 Volume 47, Issue 5 Pages 1093-1098
Takashi Tomiyasu, a, Norio Teshimaa, Shigenori Nakanob and Takuji Kawashimaa,*

Abstract: A new kinetic-catalytic method by the initial rate procedure for the determination of nanogram level of iron(III) is developed, which is based on its catalytic effect on the oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone (MBTH) with N,N-dimethylaniline (DMA) to form an indamine dye (lambda(max) = 590 nm) in the presence of hydrogen peroxide, Iron(II) is also determined, being oxidized to iron(III) by hydrogen peroxide. Calibration graphs obtained by the initial rate method are linear in the range 1-1000 ng mL-1 Fe and as low as 10^-8 M Fe(II, III) can easily be determined. The relative standard deviations are 6.6, 2.5 and 1.5% for ten determinations of 1, 20 and 60 ng mL-1 of Fe(III), respectively. The method is applicable to the determination of iron in natural waters without pre-concentration and separation.
Iron Spectrophotometry Kinetic Catalysis Micelle

"Rapid Determination Of Residual Chlorine By Flow Injection Analysis"
Analyst 1982 Volume 107, Issue 1273 Pages 433-441
D. J. Leggett, N. H. Chen and D. S. Mahadevappa

Abstract: Flow injection determination of residual chlorine in solution has been carried out spectrophotometrically by methyl orange decolorisation and by formation of a yellow complex with o-tolidine. The carrier streams are 0.180 mM methyl orange in pH 2 buffer solution or 0.01 M hydrochloric acid, and 3.0 mMo-tolidinium dichloride (in 2 M hydrochloric acid), respectively. A sampling rate of 288 samples per hour has been obtained with the latter reagent and the detection limit is 0.08 p.p.m. of chlorine. Influence of flow parameters such as flow-rate, tube length and diameter and the effect of interferents on the determination have been investigated. A study of the hyprochlorite-ammonium-o-tolidine reaction system has been performed and a method for the simultaneous determination of NH4+ and OCl- is described.
Chlorine Spectrophotometry

"Combination Of Flow Injection Analysis With Flame Atomic Absorption Spectrophotometry. Determination Of Trace Amounts Of Heavy Metals In Polluted Seawater"
Analyst 1983 Volume 108, Issue 1289 Pages 905-917
Svend Olsen, Luiz C. R. Pessenda, Jaromir Rika and Elo H. Hansen

Abstract: A Varian model AA-1275 spectrophotometer with FIAstar injection unit was used, with 0.5 mM H2SO4 as carrier solution (4.9 mL min-1), to analyze from 180 to 250 samples per h; Cd, Cu, Pb and Zn were determined at 228.8, 324.7, 217.0 and 213.9 nm, respectively, with corresponding detection limits of 9, 5, 32 and 10 ppb. Calibration graphs were rectilinear for, e.g., 2 to 20 ppm of Pb. A two-line FIAstar injection system, with directional valve and peristaltic pumps, was developed to allow analysis of seawater after pre-concentration of the metals on Chelex-100 (NH4+ form). Results showed good agreement with those obtained by potentiometric stripping analysis. Automation of the system is described.
Cadmium Copper Metals, heavy Lead Zinc Ion exchange Spectrophotometry Resin Preconcentration Chelex Tecator

"Speciation Of Metals In Solution By Flow Injection Analysis. 1. Sequential Spectrophotometric And Atomic Absorption Detectors"
Analyst 1984 Volume 109, Issue 7 Pages 839-842
Thomas P. Lynch, Nicholas J. Kernoghan and John N. Wilson

Abstract: Application of the technique is exemplified by the determination of(I) Cr(VI) and total Cr in seawater, and(II) Fe(II) and total Fe in mineral process solution In(I), Cr(VI) is determined spectrophotometrically at 540 nm with 1,5-diphenylcarbazide by a modification of the procedure of Joergensen and Regitano (cf. Anal. Abstr., 1980, 39, 4G17). Then total Cr is determined in the flow stream by AAS at 357.9 nm in an air - acetylene flame. For 30 µL samples, calibration graphs are rectilinear for 20 ppm of Cr(VI) and 50 ppm of total Cr. For 16 ppm of total Cr and 8 ppm of Cr(VI), the coefficient of variation are 1.5%. Results on 4 samples of seawater for total Cr agreed with those obtained by AAS In(II), Fe(II) is determined spectrophotometrically at 508 nm with 1,10-phenanthroline and total Fe is determined by AAS at 248.3 nm in an air - acetylene flame. With 20 µL samples, calibration graphs are rectilinear for 120 ppm of Fe(II) or total Fe. For 40 ppm of total Fe and 20 ppm of Fe(II), the coefficient of variation are 1.8 and 0.7%, respectively. In the determination of Fe(II) there is no interference from 25 ppm of Bi, 50 ppm of Mo, 120 ppm of Hg(II) or Co(II) and 200 ppm of Cu(II). With both systems, sampling rates of up to 120 h-1 are possible.
Chromium, total Chromium(VI) Iron(2+) Iron Spectrophotometry Spectrophotometry Interferences Process control Speciation

"Application Of Ion-exchanger Phase Absorptiometry To Flow Analysis. Determination Of Trace Amounts Of Chromium(IV) In Water"
Analyst 1988 Volume 113, Issue 3 Pages 471-474
Kazuhisa Yoshimura

Abstract: Ion-exchanger phase absorptiometry was applied to the determination of trace amounts of chromium(VI) in natural waters using flow analysis. The product of the reaction of chromium(VI) with 1,5-diphenylcarbazide was introduced into a carrier solution stream in the flow system. The increase in absorption by the colored complex sorbed on a cation exchanger, with which the light-path of a flow-through cell had been partly filled, could be measured directly with high precision. When 4.4 mL of sample solution were pumped through, the sensitivity obtained was 160 times higher than that of the corresponding solution method. The detection limit was as low as 0.5 ng of chromium(VI). Cations such as calcium and background electrolytes present in natural waters at high concentrations caused a change in the background attenuation. For fresh water, this effect could be removed only by passing the sample solution through a small hydrogen-form cation-exchange column. For sea water, it is necessary to use a calibration graph prepared at similar concentrations to those in the sample solution. Without pre-concentration, the proposed method is directly applicable to the analysis of natural water samples containing chromium(VI) at less than 1 µg dm-3.
Chromium(VI) Ion exchange Spectrophotometry Preconcentration

"Oxygen Removal In Flow Injection Anodic-stripping Voltammetry"
Analyst 1989 Volume 114, Issue 10 Pages 1271-1273
Eddie Boon-Tat Tay, Soo-Beng Khoo and Siau-Gek Ang

Abstract: The method involves use a new flow cell (illustrated) and a six-way valve. A Hg-film electrode is formed by deposition on vitreous carbon, in the presence of O, at -1.0 V for 30 s, and the sample solution is then passed through the cell for deposition of metals at -0.8 V. After deposition, the sample solution is replaced by the stripping solution (0.1 M Na acetate buffer, pH 4.5), which is purged with N to remove O. The metals are determined by anodic-stripping voltammetry by scanning at 10 mV s-1 from -0.8 to 0 V. The method was applied in the determination of Cu, Pb and Cd in seawater. The corresponding limits of detection were 1.2, 0.8 and 0.75 nM with a flow rate of 3.1 mL min-1 and deposition for 3 min. The coefficient of variation were 5% for 5 nM and 2% for 0.5 µM.
Copper Cadmium Lead Voltammetry Electrode Valve Buffer Detection limit Flowcell

"Flow Injection Procedure For The Determination Of Tertiary Amines In Water And Seawater Using Chemiluminescence Detection"
Analyst 1989 Volume 114, Issue 12 Pages 1659-1661
J. Steven Lancaster, Paul J. Worsfold and A. Lynes

Abstract: Sample was injected into a stream of borate buffer (pH 11.0), which merged first with 1 mM rhodamine B and then with 1.64 mM NaOCl (all at 1 mL min-1); detection of chemiluminescence was by a photomultiplier tube. The calibration graph for triethylamine was rectilinear for 0.2 mM in water and 0.1 mM in seawater. Coefficients of variation were generally 2% (n = 5). The method can also be used to determine trimethyl- and tripropyl-amine. Quenching of the chemiluminescence occurs in the presence of a 10-fold excess of diethylamine or ethylamine.
Trimethylamine Triethylamine Tripropylamine Amines, alkyl Chemiluminescence Buffer Quenching Indirect

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

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

"Flow Injection Spectrophotometric Determination Of Boron With D-sorbitol Using Methyl Orange As An Indicator"
Analyst 1991 Volume 116, Issue 7 Pages 711-714
Kazuko Nose and Michio Zenki

Abstract: Sample solution was injected into a carrier stream (1 mL min-1) of water or aqueous 0.6% NaCl (for seawater) and mixed with a stream (1 mL min-1) of 0.2 mM methyl orange (C.I. Acid Orange 45) in 1.25 M D-sorbitol. The mixture was passed through a reaction coil (4 m x 0.5 mm) and the absorbance was measured at 520 nm. The calibration graph was almost rectilinear up to 1.2 mg L-1 of B and the detection limit was 20 µg l-1. The coefficient of variation was 0.3 and 0.5% for 0.5 and 1.2 mg L-1 of B, respectively. The sampling rate was ~20 h-1. The method was applied to eye lotions and seawater; recoveries were 98 to 102% and 96 to 104%, respectively.
Boron Spectrophotometry

"Shipboard Flow Injection Method For The Determination Of Manganese In Seawater Using In-valve Preconcentration And Catalytic Spectrophotometric Detection"
Analyst 1991 Volume 116, Issue 7 Pages 707-710
I. Ya. Kolotyrkina, L. K. Shpigun, Yury A. Zolotov and G. I. Tsysin

Abstract: Sample was applied to a micro-column (1 cm x 2.5 mm) of DETATA fibrous sorbent (H+ form; cf. Tsysin et al., Zh. Neorg. Khim., 1990, 34, 960) and the Mn adsorbed was eluted with 0.5 M HCl or HNO3. The eluate was mixed with 10 mM KIO4 in phosphate buffer solution and NN-diethylaniline in dilute HCl amd the increase in absorbance at 470 nm was recorded. Preconcentration times of 10 s to 10 min allowed determination of 20 µg L-1 to 10 ng L-1 of Mn. The coefficient of variation were 5 to 8% and a sampling rate of 15 h-1 was achieved. Recoveries of 50 ng L-1 to 10 µg L-1 of Mn were 97 to 118%. The method was applied to the direct shipboard measurement of Mn in deep seawater samples.
Manganese Spectrophotometry Buffer Catalysis Column Preconcentration

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

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

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

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

"Batch And Flow Determination Of Uranium(VI) By Adsorptive Stripping Voltammetry On Mercury-film Electrodes"
Analyst 1994 Volume 119, Issue 2 Pages 279-285
Anastasios Economou, Peter R. Fielden and Andrew J. Packham

Abstract: U(VI) was determined by square wave adsorptive stripping voltammetry on a rotating disc mercury-film electrode using 8-hydroxyquinoline as a complexing agent (batch mode) or on a wall jet mercury-film electrode with cupferron as complexing agent (flow-through mode). For the flow-through configuration, the combination of a novel wall jet cell with an automated flow system and a commercial computer controlled potentiostat allowed complete keyboard control of the sequence of operations. Continuous-flow and flow injection schemes for pre-concentration were assessed; various instrumental parameters are discussed. Calibration graphs were linear over two orders of magnitude for 60 s pre-concentration times. Batch and continuous-flow methods were more suitable for the determination 0.1 µM-U(VI) whereas flow injection was ideal for the determination of 0.1 µM-U(VI). The batch and flow methods were applied to the analysis of seawater with RSD of 7.8% and 8.3%, respectively.
Uranium(VI) Voltammetry Electrode 8-Hydroxyquinoline Preconcentration

"Determination Of Micro-amounts Of Phosphorus With Malachite Green Using A Filtration-dissolution Preconcentration Method And Flow Injection Spectrophotometric Detection"
Analyst 1995 Volume 120, Issue 1 Pages 187-191
Joko P. Susanto, Mitsuko Oshima, Shoji Motomizu, Hiroshi Mikasa and Yoshikazu Hori

Abstract: Sample solution (10 ml) was mixed with 1 mL 6.5 M HCl and 1 mL reagent solution (prepared by dissolving 7.1 g ammonium heptamolybdate in 30 mL water and adding 48 mL concentrated HCl and 10 mL malachite green solution containing 0.023 g malachite green oxalate; the solution was diluted to 100 mL with water, mixed for 12 h and filtered). The mixture was allowed to stand for 5 min and was then filtered through a cellulose nitrate membrane filter under suction. The solid was washed with 10 mL water. The solid and the membrane filter were dissolved in 1 mL methyl cellosolve. A portion (100 µL) of the resulting solution was injected into a carrier stream (0.5 ml/min) of methyl cellosolve and the absorbance was measured at 627 nm (ε = 210 000). The calibration graph was linear up to 19 ppb of P; the detection limit was 0.06 ppb. The RSD (n = 6) was 0.57%. The method was used to determine P (as phosphate) in seawater.
Phosphorus Spectrophotometry Preconcentration

"Application Of Flow Injection Spectrophotometry To The Determination Of Dissolved Iron In Seawater"
Analyst 1995 Volume 120, Issue 1 Pages 201-206
Irina Ya. Kolotyrkina, Lilija K. Shpigun, Yury A. Zolotov and Alexander Malahoff

Abstract: Two flow injection methods are described. In the first method, streams of acidified seawater and 1 M ammonium acetate were mixed and the resulting solution was pumped through a microcolumn (1 cm x 2.5 mm i.d.) packed with diethylenetriamine sorbent for 3-10 min. After washing the column with water, elution was effected by pumping a carrier stream of 0.5 M HCl through the column for 80 s. The column eluate was mixed with a reagent stream of 1 mM p-phenetidine and 9.4 mM o-phenanthroline and subsequently with a second reagent stream of 1 M ammonium acetate and 9 mM NaIO4. The mixture was passed through a reaction coil maintained at 40°C and the absorbance was measured at 540 nm. The detection limit was 0.05 µg/l of Fe. The RSD (n = 4) was 2.4-8.1%. Recoveries were 103-110%. In the second method, 300 µL 0.01 M N,N-dimethyl-p-phenylenediamine were injected into a carrier stream of Fe-depleted acidified seawater and mixed with the acidified seawater sample stream. The resulting solution was mixed with a reagent stream of 0.12% H2O2 in 2 M ammonium acetate buffer and the absorbance was measured at 554 nm. The detection limit was 0.03 µg/l of Fe. The RSD (n = 4) was 1.8-6%. Recoveries were 98-105%.
Iron Spectrophotometry Column Heated reaction

"Determination Of Ninhydrin Positive Substances In Seawater And Hemolymph"
Analyst 1995 Volume 120, Issue 8 Pages 2097-2099
Saloua Sadok, Roger Uglow and Stephen J. Haswell

Abstract: A flow injection spectrophotometric method for determining ninhydrin positive substances (α-amino-acids) in seawater and in hemolymph from mussels (Mytilus edulis) is described. Hemolymph was diluted with saline before analysis; seawater was used directly. The sample (0.5 ml) was mixed with 1 mL 3% ninhydrin and heated in a boiling-water bath for 12 min, 1 mL 0.8 M HCl was added and the mixture was heated for a further 10 min. A portion (0.3 ml) of the solution was injected into an aqueous carrier stream (1 ml/min) and mixed with a stream (1 ml/min) of 1.2 M NaOH in a 15 cm mixing coil to produce NH3. The solution was then passed over a microporous PTFE membrane through which the NH3 diffused into a stream (1 ml/min) of 0.4 g/l Bromothymol Blue. The absorbance of the colored solution was measured at 635 nm. The calibration graph was linear up to 60 µM-alanine and the detection limit was 0.3 µM. The RSD (n = 6) was 2%. Recoveries were quantitative.
Amino acids, α Spectrophotometry Teflon membrane Gas diffusion

"Shipboard Determination Of Dissolved Cobalt In Seawater Using Flow Injection With Catalytic Spectrophotometric Detection"
Analyst 1996 Volume 121, Issue 8 Pages 1037-1041
Alexander Malahoff, Irina Ya. Kolotyrkina and Lilly K. Shpigun

Abstract: Seawater was filtered and acidified to pH 2. A portion (200 µL) was injected into a carrier stream of acidified seawater depleted of Co at a flow rate of 1.5 ml/min and mixed with a reagent stream of 0.01 M N,N'-diethyl-p-phenylenediamine/0. 01 M Tiron at a flow rate of 0.8 ml/min. The combined reagent/sample stream was merged with a stream of 0.2% H2O2/0.04 M NaOH/0.02 M sodium tetraborate at a flow rate of 0.6 ml/min. The mixture was passed through a 2.2 m reaction coil maintained at 30°C; absorbance was measured at 554 nm. A diagram of the manifold used is given. The calibration graph was linear from 0-300 ng/l Co; the detection limit was 1 ng/1. RSD was 1.6-10.6% (n = 5). Recoveries were 101-113% Co. The throughput was 50 samples/h.
Cobalt Spectrophotometry Tiron Heated reaction

"Determination Of Ultratrace Amounts Of Antimony(III) In Water By Flow Injection Online Sorption Preconcentration In A Knotted Reactor Coupled With Electrothermal Atomic Absorption Spectrometry"
Analyst 1996 Volume 121, Issue 8 Pages 1061-1067
Xiu-Ping Yan, Willy Van Mol and Freddy Adams

Abstract: The sample was acidified to be 0-1 M in HCl and was merged at a flow rate of 5.4 ml/min with a reagent stream of 0.02% ammonium pyrrolidine dithiocarbomate (APDC) at 1.4 ml/min. The resulting chelate was concentrated on to the inner walls of PTFE knotted reactor (100 cm x 0.5 mm i.d.); the pre-concentration took 30 s. The adsorbed chelate was washed with a stream of 0.02% APDC/0.02% HNO3 at a flow rate of 3 mL/min. The residual solution was removed by an air stream then the chelate was eluted from the knotted reactor with 35 µL ethanol delivered by a stream of air at a flow rate of 3 mL/min. The eluate was analyzed for Sb(III) by ETAAS using drying, pyrolysis and atomization temperatures of 90, 800 and 2000°C, respectively (other experimental conditions tabulated); detection was at 217.6 nm. The calibration graph was linear from 0.1-2 µg/L Sb(III); the detection limit was 0.021 µg/L. RSD (n = 11) was 2.9%. The throughput was 42 samples/h. The method was applied to seawater. Recoveries of Sb(III) were quantitative.
Antimony Spectrophotometry Preconcentration Knotted reactor Ultratrace Chelation

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

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

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

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

"Determination Of Cadmium In Environmental Samples By Hydride Generation With In Situ Concentration And Atomic Absorption Detection"
Analyst 1997 Volume 122, Issue 4 Pages 331-336
Henryk Matusiewicz, Mariusz Kopras and Ralph E. Sturgeon

Abstract: A continuous-flow AAS system for Cd determination is described. A Cd solution acidified with HCl was mixed with 1 µg/ml Co and 0.5% thiourea (and also with 0.01 M didodecyldimethyl-ammonium bromide for reaction with KBH4) and diluted to 1 mL with water. The resulting solution was aspirated at a flow rate of 1 ml/min into a continuous-flow system and merged with a stream of either 2% NaBH4 or 4% KBH4 at a flow rate of 1 ml/min. The mixture was passed through a reaction cell/gas-liquid separator maintained at 50°C and the volatile Cd species evolved were carried by an Ar stream on to the inner wall of a GF for in situ pre-concentration at 200°C. Cd analysis was by ET AAS with atomization at 1800°C for 3 s; detection was at at 228.8 nm. The detection limit was 10 ng/l Cd with KBH4 as reagent. RSD were 10^-14% (n = 10). The method was applied to several environmental and biological CRM. The results obtained agreed with the certified values.
Cadmium Spectrophotometry Heated reaction Volatile generation Reference material Phase separator Preconcentration Volatile generation

"Use Of A Bentonite-modified Carbon-paste Electrode For The Determination Of Some Phenols In A Flow System By Differential Pulse Voltammetry"
Analyst 1997 Volume 122, Issue 6 Pages 601-604
Ignacio Naranjo Rodr&iacute;guez, Juan A. Mu&ntilde;oz Leyva and Jos&eacute; L. Hidalgo Hidalgo de Cisneros

Abstract: The behavior of various phenols at the cited electrode in a flow system was studied. A sample (0.25 ml) was injected into a carrier stream of either Britton-Robinson buffer of pH 4 or formate buffer of pH 4-5 at a flow rate of 1.25 ml/min. Differential-pulse voltammetric measurements were made at a C paste electrode modified with 5-10% bentonite. Both flow injection and stopped-flow modes were employed. The following phenols: 2,4-Dinitrophenol (I), 2-methyl- 4,6-dinitrophenol (II) and 2,4-dimethylphenol (III) showed good electroanalytical behavior at the bentonite-modified electrode, enabling these compounds to be determined successfully. However, pentachloro-phenol and 4-chloro-3-methylphenol could not be determined satisfactorily owing to a lack of stability of the electrode surface. The method was used to determine I-III in spiked seawater: recoveries were 95-101%.
Phenols 2,4-Dinitrophenol 2-Methyl-4,6-dinitrophenol 2,4-Dimethylphenol Voltammetry Electrode Electrode Buffer Stopped-flow

"Fully Automatic Online Separation Preconcentration System For Electrothermal Atomic Absorption Spectrometry: Determination Of Cadmium And Lead In Seawater"
Analyst 1997 Volume 122, Issue 7 Pages 679-684
Facundo M. Fern&aacute;ndez, Jorge D. Stripeikis, Mabel B. Tudino and Osvaldo E. Troccoli

Abstract: A fully automated system for analyte separation and pre-concentration prior to ET AAS determination is described. Preconcentration is performed on a chelating resin microcolumn (Chelex-100) placed in the injection tip of the graphite furnace autosampler. A time-based computer-controlled flow injection manifold is used for column conditioning, pre-concentration and washing steps. Elution is performed in a single step by the programmable graphite furnace autosampler; both complete and partial injection of the eluate into the graphite furnace for ET AAS analysis are possible. Diagrams of the manifold used, illustrating the sequence of operations involved, are given. The system was used to determine Cd and Pb in seawater. Detection limits of 0.9 and 8 ng/l were obtained for Cd and Pb, respectively. The RSD (n = 10 or 15) were 2.7-4%.
Cadmium Lead Sample preparation Spectrophotometry Automation Chelation Chelex Column Detection limit Preconcentration Computer

"Determination Of Iodide In Brines By Membrane Permeation Flow Injection Analysis"
Analyst 1997 Volume 122, Issue 11 Pages 1235-1237
J. T. H&aring;kedal and P. K. Egeberg

Abstract: A flow injection method is described for the determination of iodide based on the oxidation of iodide to iodine, which after permeation through a PTFE membrane is detected spectrophotometrically. The sample is injected into a carrier stream of water and merged with acidic dichromate reagent, oxidising iodide to iodine. The iodine permeates through the membrane into a collector stream containing iodide, The iodine reacts with iodide forming triiodide, and is measured spectrophotometrically in a flow cell at 350 nm, The repeatability of the technique was better than a relative standard deviation of 2% at 5 mg L-1 level, with a throughput of 50 samples hr-1, The detection limit was 0.2 mg L-1 iodide, The method is suitable for analyzing high saline waters, No significant matrix effect is found for seawater up to 32 parts per thousand S, or sodium chloride concentrations up to 50 g L-1, The method is tested for potential interfering substances (Br-, COOH, CH3COOH, HCO3-, Fe2+, Mn2+ and S2-), The only interfering compound found was sulfide, which can be removed by preheating the samples after acidification. The method was tested by analyzing marine pore water samples from Ocean Drilling Program Leg 164; the results compared well with data obtained by the manual method. 17 References
Iodide Spectrophotometry Detection limit Interferences Redox Membrane Teflon membrane Method comparison

"Determination Of Selenium Species In Seawater By Flow Injection Hydride Generation In Situ Trapping Followed By Electrothermal Atomic Absorption Spectrometry"
Analyst 1998 Volume 123, Issue 7 Pages 1565-1569
Jean Yves Cabon and Wolfgang Erler

Abstract: In this study, Se(IV) was determined in seawater by flow injection hydride generation, trapping within the graphite furnace, followed by electrothermal atomic absorption spectrometry. The optimized protocol permitted a pre-concentration factor of 1000 lowering the detection limit of Se(IV) in seawater to about 1.5 ng L-1 for a 25 mL sample volume Because this technique is specific to Se(IV), various physico-chemical treatments leading to the conversion of other chemical forms into Se(IV) were investigated. Thermal and UV irradiation treatments of seawater samples in acidic or basic medium permitted the conversion of Se(II)-selenomethionine and Se(VI) to Se(IV). Based on the different responses of selenium species towards the photochemical treatments, an operational speciation model of selenium species in seawater is proposed. According to our anal. protocol, 21 ng L-1 Se(VI), 10 ng L-1 Se(IV) and 13 ng L-1 organic Se(II) species were determined in a coastal surface seawater collected near Brest. (34 References)
Selenium(IV) Selenomethionine Spectrophotometry Speciation Volatile generation Optimization UV reactor Heated reaction

"Trace Enrichment And Determination Of Sulfate By Flow Injection Inductively Coupled Plasma Atomic Emission Spectrometry"
J. Anal. At. Spectrom. 1987 Volume 2, Issue 6 Pages 553-555
Alan G. Cox, Cameron W. McLeod, Douglas L. Miles and Jennifer M. Cook

Abstract: The sample was injected into a stream of 0.01 M HNO3, and SO42- was retained on a column (2.5 cm x 1.5 mm) of acidic alumina, from which it was eluted by injection of 0.2 mL of aqueous 2 M NH3, and carried to the ICP for determination at 180.73 nm. Residual SO42- was eluted with further NH3, and the recovery was calculated as the ratio of peak areas for replicate injections of SO42- solution with and without the alumina column in the stream. The calibration graph was rectilinear for up to 1 mg L-1 of SO42- (2 mL injections), the detection limit was 2.8 µg l-1, and the coefficient of variation (n = 7) at 10 µg L-1 and 1 mg L-1 were 7 and 0.8%, respectively. The method was applied to various natural waters (seawater was diluted two-hundredfold), with results in good agreement with those by conventional ICP-AES. The method was also applied to boiler-feed water.
Sulfate Spectrophotometry Alumina Column Preconcentration Method comparison

"High-efficiency Low-sample-consumption Online Ion-exchange Preconcentration System For Flow Injection Flame Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1989 Volume 4, Issue 6 Pages 543-546
Zhaolun Fang and Bernhard Welz

Abstract: The cited system was used for determination of heavy metals. Only 1.6 mL of sample solution was required for analysis, 120 samples h-1 could be analyzed, and enrichment factors of 25 to 31 were achieved for Cu, Cd and Pb. The coefficient of variation were 1.2 to 2.8%; e.g., for 100 µg L-1 of Cu the coefficient of variation was 1.5% (n = 81). The CPG/8-Q ion exchanger was used, and conical columns, short, small-bore conduits and three-dimensional disoriented reactors were used to limit the dispersion of the eluted sample zone. Low elution flow rates and high nebulizer uptake rates were used to improve nebulization efficiency. Application of the method in analysis of seawater is discussed.
Copper Cadmium Lead Metals, heavy Spectrophotometry Small sample Resin Column Dispersion Nebulizer Preconcentration

"Effect Of Ion-lens Tuning And Flow Injection On Non-spectroscopic Matrix Interferences In Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1990 Volume 5, Issue 6 Pages 445-449
Jiansheng Wang, Wei-Lung Shen, Brenda S. Sheppard, E. Hywel Evans, Joseph A. Caruso and Fred L. Fricke

Abstract: The effects on the 138Ba+ signal of Co, Pb and synthetic seawater in ICP-MS were studied as a model for general non-spectroscopic matrix interference, and to examine ways to minimize such interference. Each matrix suppressed the signal, with Pb having the largest effect. Suppression was compensated for, in part, by using In as internal standard, and by tuning the ion lenses for the analyte in presence of the matrix, rather than for an acidic standard solution. Flow injection and continuous sample introduction showed no significant difference. By continual reference of analyte signals with and without matrix, any bias due to nebulizer or cone blockage was effectively eliminated.
Barium Mass spectrometry Interferences Internal standard

"Flow Injection Online Sorbent Extraction Preconcentration For Graphite Furnace Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1990 Volume 5, Issue 7 Pages 639-646
Zhaolun Fang, Michael Sperling and Bernhard Welz

Abstract: A micro-flow injection online sorbent extraction pre-concentration system was developed to improve the performance of flame and graphite-furnace AAS. Lead was determined as a test element. A Perkin-Elmer Model 2100 spectrometer was used at 283.3 nm. A 26-fold enhancement in peak area compared with 50 µL direct introduction was obtained with pre-concentration. for 60 s while achieving a coefficient of variation of 1.9% (n = 11) for 0.1 µg L-1 of Pb and a detection limit of 3 ng l-1. Determination of Pb in seawater revealed that the interfering matrix had been almost completely removed during pre-concentration. Results obtained for some National Research Council of Canada Standard Reference Materials agreed well with certified values.
Lead Spectrophotometry Sample preparation Preconcentration Detection limit Interferences Reference material Solid phase extraction

"Determination Of Ultra-trace Levels Of Metal Ions In Seawater With Online Preconcentration And Electrothermal Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1991 Volume 6, Issue 2 Pages 119-122
V. Porta, O. Abollino, E. Mentasti and C. Sarzanini

Abstract: An on-line pre-concentration system for electrothermal atomic absorption spectrometry was developed. A miniature silica C18 column was inserted at the tip of the autosampler arm. A modification of the tubing line of the autosampler allowed either the flow of the sample through the column or the operation of the autosampler in the normal mode. The retention of the metal ions in the form of complexes on the microcolumn was achieved by using pyrrolidin-l-yl dithioformate as the complexing agent; acetonitrile was then used for the elution. The direct injection of the eluate into the graphite furnace gave high pre-concentration factors, ranging between 20 and 225, which are sufficient for the determination of Cd, Pb, Cu, Ni, Co and Fe in Antarctic sea-water. The blank level was very low and the detection limits ranged from 0.4 ng l-1(Cd) to 25 ng l-1(Fe).
Metals, heavy Spectrophotometry Chelex Column Preconcentration Resin Ultratrace

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

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

"Optimization And Use Of Flow Injection Vapor-generation Inductively Coupled Plasma Mass Spectrometry For The Determination Of Arsenic, Antimony And Mercury In Water And Seawater At Ultra-trace Levels"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 1 Pages 35-40
Andreas Stroh and Uwe V&ouml;llkopf

Abstract: An Elan 5000 ICP mass spectrometer and a FIAS-200 equipped with an AS-90 autosampler for online flow injection vapor generation (all from Perkin-Elmer) were used with Ar as plasma and purge gas for the cited analyzes; the optimized operating conditions are specified. The sample solution was injected into 3% HNO3 as carrier rather than HCl (to avoid formation of ArCl, which could interfere with the 75As signal) and the resulting stream was mixed with 0.2% NaBH4 solution The hydrides were entrained in Ar and, after passage through a gas - liquid separator, introduced into the plasma. Bismuth was used as internal standard. Detection limits ranged from 0.5 ng L-1 for Bi to 16 ng L-1 for 78Se; pre-reduction with KI improved the detection limits for As and Sb to 6 and 1.3 ng l-1, but impaired that for Hg. The coefficient of variation (n = 5) ranged from 0.5 to 1.6%. Results obtained for four reference water samples agreed with the certified values.
Arsenic Antimony Mercury Mass spectrometry Optimization Ultratrace Interferences Reference material FIAS-200

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

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

"Determination Of Trace Metals In Concentrated Brines Using Inductively Coupled Plasma Mass Spectrometry Online Preconcentration And Matrix Elimination With Flow Injection"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 7 Pages 979-981
Les Ebdon, Andrew Fisher, Howard Handley and Philip Jones

Abstract: Two chelation ion-exchange columns, an in-house (xylenol orange) one and a commercial (Metpac CC-1) one, were used for matrix elimination and online pre-concentration of the analytes (the alkaline-earth and first-row transition metals) before their determination in brines by ICP-MS with a VG Plasmaquad II instrument. Residual Na was determined by flame AAS. The method was used to determine the metals in seawater reference material NASS-3 (National Research Council of Canada). The response was linear in the range of interest (200 µg/l), and excellent agreement with the certified values was achieved. At the pH used, the in-house column retained all the alkaline-earth metals, but the transition metals were retained only slightly, so recovery was poor. The Metpac CC-1 column retained all the metals investigated and gave good precision.
Metals, trace Mass spectrometry Spectrophotometry Chelation Column Preconcentration Metpac Reference material

"Determination Of Ultratrace Amounts Of Cobalt In Ocean Water By Laser-excited Atomic Fluorescence Spectrometry In A Graphite Electrothermal Atomizer With Semi Online Flow Injection Preconcentration"
J. Anal. At. Spectrom. 1994 Volume 9, Issue 11 Pages 1195-1202
Alexander I. Yuzefovsky, Robert F. Lonardo, Mohui Wang and Robert G. Michel

Abstract: A flow injection, semi online, microcolumn pre-concentration system consisting of C18 functional groups (schematic given) was used as described previously (cf. Microchem. J., 1993, 48, 326). The microcolumn was integrated with laser-excited AFS in an electrothermal atomizer. Two ocean water reference materials, viz., CASS-2 and NASS-4, NASS-4 and CASS-2 were mixed with sodium diethyldithiocarbamate in pH 9 buffer to pH 2.5 and 2.4, respectively. The solutions were pumped directly onto the column at 0.15 ml/min. Sub-boiled water was passed through the column at the same flow rate and in the same direction. Ethanol was then passed through at the same flow rate but in the reverse direction. The ethanol eluate containing Co was then collected and delivered directly onto the L'vov platform. A 40 µL portion was analyzed. The detection limit based on a 12.5-fold pre-concentration was 1 ng/l of Co. RSD were 9 and 13% for CASS-2 and NASS-4, respectively.
Cobalt Spectrophotometry Fluorescence Reference material Preconcentration Ultratrace

"Continuous Hydride Generation Low-pressure Microwave-induced Plasma Atomic Emission Spectrometry For The Determination Of Arsenic, Antimony And Selenium"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 4 Pages 311-315
Florian Lunzer, Rosario Pereiro-Garc&iacute;a, Nerea Bordel-Garc&iacute;a and Alfredo Sanz-Medel

Abstract: The direct coupling of on-line continuous hydride generation methods to low-pressure microwave-induced Ar and He plasmas, sustained in a surfatron, was evaluated for the determination of trace amounts of arsenic, antimony and selenium by atomic emission spectrometry. The effect of the hydrogen produced during the hydride generation step, the optimization of the operating conditions for He and Ar plasmas and the figures of merit of the analytical systems are given. Detection limits (3s) of 0.7, 0.9 and 4.1 ng ml-1 were obtained for As, Sb and Se, respectively, using an Ar plasma at 50 Torr (1 Torr = 133.322 Pa) and a power of 115 W. The relative standard deviations, calculated at the 50 ng ml-1 level, were in the range 3-4% for the three elements. Poorer detection limits were obtained for He than for Ar discharges (by about two to five times, depending on the emission line). Using an argon discharge, the method was applied successfully to the determination of As in sea-waters.
Arsenic Antimony Selenium Spectrophotometry Volatile generation Volatile generation

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

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

"Application Of Multielement Time-resolved Analysis To A Rapid Online Matrix Separation System For Inductively-coupled Plasma-mass Spectrometry"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 11 Pages 929-933
Simon M. Nelms, Gillian M. Greenway and Robert C. Hutton

Abstract: A rapid online matrix separation system for ICP-MS, using multi-element time-resolved analysis, was developed for the determination of several trace elements in complex matrix samples, A flow injection manifold was constructed consisting of a mini-column of 8-hydroxyquinoline covalently immobilized on to controlled pore glass, Analytes retained on the column were eluted using 0.1 mi of 2.0 mol L-1 nitric acid, Sample volumes of 0.5 mi were analyzed, yielding a pre-concentration factor of 5 in addition to matrix separation, The system was optimized with respect to the variables of buffer concentration, buffer pH and eluent acid volume and concentration, Calibrations from both pure water and synthetic seawater compared well and showed good linearity, with correlation coefficients of 0.988-0.999 for a range of analytes, The method showed good within-run reproducibility with precisions (s(r)) at the 1 ng mL-1 level of typically <3%, In general, recoveries between 89 and 104% were obtained, with the exception of Ni, which showed a recovery of 78% under the compromise conditions used. The method was validated by the analysis of estuarine (SLEW-1) and coastal (CASS-2) certified reference materials, Good agreement with the certified values was obtained for both of these materials. (17 references)
Metals, trace Mass spectrometry Sample preparation 8-Hydroxyquinoline Controlled pore glass Optimization Preconcentration Reference material Solid phase extraction

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

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

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

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

"Online Solid-phase Chelation For The Determination Of Eight Metals In Environmental Waters By Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 3 Pages 187-191
Daniel B. Taylor, H. M. Kingston, Donald J. Nogay, Dagmar Koller and Robert Hutton

Abstract: Seawater was mixed with 4 M ammonium acetate buffer, the pH was adjusted to 5.5 and diluted with water. The prepared seawater or natural water was loaded into a flow injection system at 2.4 ml/min and the sample merged with a buffer solution (2 ml/min) of 4 M ammonium acetate of pH 5.8 which had passed through a clean up Al-clad PEEK column (7.5 cm x 4.6 mm i.d.) packed with Muromac A-1 (50-100 mesh). The resulting solution was loaded on to a PEEK column (5 cm x 4 mm i.d.) and the column was washed with water. Weakly retained matrix components were eluted with buffer and the buffer was washed off the column with water. The metal analyzes were eluted with 1 M HNO3 and the eluate passed to the ICP-MS instrument via a V groove nebulizer. Eight metals (14 isotopes) were determined with detection limits of 0.5-60 ng/l for a 10 mL sample to 0.11-12 ng/l for a 50 mL sample (results tabulated). The results for the analysis of water reference materials are tabulated and discussed.
Metals Mass spectrometry Sample preparation Reference material Chelation Solid phase extraction Muromac

"Determination Of Mercury In Filtered Seawater By Flow Injection With Online Oxidation And Atomic Fluorescence Spectrometric Detection"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 7 Pages 511-514
Martin J. Bloxham, Steve J. Hill and Paul J. Worsfold

Abstract: A flow injection (FI) atomic fluorescence method incorporating an online bromide-bromate oxidation step to determine mercury in filtered seawater samples at the ng L-1 level is described. A heated reaction coil was incorporated in the FI manifold to increase the conversion of organic mercury into inorganic mercury(II) chloride from 50 to approaching 100%. Detection limits (3s) for mercury(II) chloride and methylmercury chloride were 25 and 23 ng L-1 Hg, respectively. The FI manifold could also be used to determine the total mercury concentration in biological materials and was validated by analyzing the CRM TORT-1 Lobster Hepatopancreas. Good agreement with the certified (330±60 µg l-1) value was achieved (353±64 pg l-1). The analysis of coastal water samples from Sutton Harbour, Plymouth, showed that mercury levels ranged from 24±5 to 54±10 ng l-1.
Mercury(II) Fluorescence Reference material

"Direct Determination Of Trace-metals In Seawater Using Electrothermal Vaporization Inductively-coupled Plasma-mass Spectrometry"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 8 Pages 549-553
Graeme Chapple and John P. Byrne

Abstract: A method is described for the direct analysis of five transition elements (Go, Cu, Mn, Ni, V) in sea-mater using ETV-ICP-MS, Interferences from the seawater matrix were eliminated by a combination of in situ separation of analyte and matrix components in the ETV, and use of nitric acid as a chemical modifier, The nitric acid facilitates the removal of chloride from the seawater matrix during the sample drying stage, whilst optimization of the ETV heating program allows for effective separation of residual matrix and analyte species, thus reducing ionization suppression and space charge effects in the ICP-MS, Calibration standards, prepared by spiking a seawater matrix stripped of trace metals by ion exchange, gave excellent linearity and allowed for direct determination of selected analytes without the use of standard additions, Detection limits ranged from 0.003 µg L-1 for V to 0.14 µg L-1 for Cu. The precision and accuracy of the method mere checked by analysis of two certified reference sea-waters.
Metals, trace Cobalt Copper Manganese Nickel Vanadium Mass spectrometry Reference material 8-Hydroxyquinoline Interferences Optimization

"Evaluation Of Controlled-pore Glass-immobilized Iminodiacetate As A Reagent For Automated Online Matrix Separation For Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 10 Pages 907-912
Simon M. Nelms, Gillian M. Greenway and Dagmar Koller

Abstract: A 0.04 g portion of PROSEP Chelating-1 iminodiacetate reagent (Bioprocessing, Consett, Co. Durham, UK) was packed as dry powder into a glass column (2.5 cm x 3 mm) that was incorporated in a flow injection manifold (diagram presented). A 3 mL sample was injected into a stream of H2O; transition-metal, U and Pb cations were retained on the column and subsequently eluted in an elution volume of 0.3 mL with 0.5 M HNO3. Calibration graphs prepared on the basis of water and seawater as matrices agreed, and both sets showed good linearity. RSD (n = 5) at 5 ng/ml were 5%, and recoveries were 62-113% for all the metals except Mn (35%).
Metals, heavy Mass spectrometry Controlled pore glass Iminodiacetate

"Use Of Flow Injection Cold Vapor Generation And Preconcentration On Coated Graphite Tubes For The Determination Of Cadmium In Seawater By Electrothermal Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 11 Pages 1081-1086
Pilar Bermejo-Barrera, Jorge Moreda-Pi&ntilde;eiro, Antonio Moreda-Pi&ntilde;eiro and Adela Bermejo-Barrera

Abstract: Seawater was collected in 100 mL glass bottles and acidified with 0.1 mL 16 M HNO3 to prevent adsorption of Cd(II) on the glass walls. Portions (9 ml) were treated with HCl and gallium(III) nitrate to give final concentrations of 0.25 M and 0.5 µg/ml of Ga in 10 mL. This solution (0.5 ml) was injected into the carrier, 0.25 M HCl, which was pumped into the generator at 9 ml/min for 30 s, together with 2% NaBH4 in 0.5% NaOH, pumped at 5 ml/min for 30 s. The CdH2 generated was transferred through a quartz tube (2 cm x 0.5 mm i.d.) to the integral platform of a pyrolytic graphite furnace tube with a stream of Ar (150 ml/min) for 30 s. The furnace tube had been coated with Ir (details given); at 20°C the CdH2 was rapidly adsorbed to the coating. The Cd was then atomized at 1300°C for 4 s without gas flow and measured at 228.8 nm. The Ga(III) gave the best catalytic yield of CdH2 of several cations tried. Calibration graphs (no ranges given) in the carrier solution or prepared from synthetic or real seawater by standard additions had similar slopes, indicating no matrix interference; the detection limit was 4 ng/l. At 0.25-0.5 ng/l the in batch RSD were 0.2-0.4% (n = 11). The method was applied to six seawater samples (0.04-1.2 µg/1) giving RSD of 1.6-4.2% (n = 4).
Cadmium Spectrophotometry Interferences Preconcentration Standard additions calibration

"Use Of Flow Injection Cold Vapor Generation And Preconcentration On Coated Graphite Tubes For The Determination Of Mercury In Polluted Sea Waters By Electrothermal Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 3 Pages 317-321
Pilar Bermejo-Barrera, Jorge Moreda-Pi&ntilde;eiro, Antonio Moreda-Pi&ntilde;eiro and Adela Bermejo-Barrera

Abstract: Methods have been developed for the trace determination of total and inorganic mercury in natural waters by cold vapor generation-trapping and atomization in a graphite furnace by selective reduction with NaBH4 and SnCl2. Iridium, tungstate and zirconium coated graphite tubes were investigated for the pre-concentration of the mercury vapor, The carrier solution was 0.4 M of HCl, and 0.2% NaBH4 and 1.0% SnCl2 were used as reducing solutions for total and inorganic mercury, respectively, Using iridium coated graphite tubes characteristic masses of 300 and 240 pg for total and inorganic mercury, respectively, and detection limits of 90 and 60 ng L-1 for total and inorganic mercury were obtained for a 1500 µl sample volume. The precision was between 0.7 and 2.1%, Accuracy of method was confirmed by the analysis of IAEA/W-4 fresh water reference material. 34 References
Mercury Methylmercury ion Spectrophotometry Preconcentration Volatile generation Reference material Volatile generation

"Automated Continuous-flow Hydride Generation With Inductively Coupled Plasma Mass-spectrometric Detection For The Determination Of Trace Amounts Of Selenium(IV), And Total Antimony, Arsenic And Germanium In Seawater"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 4 Pages 409-415
SRI JUARI SANTOSA, HIROSHIGE MOKUDAI and SHIGERU TANAKA

Abstract: A diagram of the apparatus is presented, and the optimization of the conditions [tetrahydroborate and HCl concentrations, the prereduction of Sb(V) to Sb(III) with cysteine, and matrix modification with methanol] is discussed. Single Sb, As and Ge compounds are used for calibration. The matrix modification with 10% (v/v) of methanol brings the recoveries significantly closer to 100%. The detection limits for Sb, As, Ge and Se are 2.2, 6.5, 2.4 and 0.5 ng/l, respectively. The RSD for standard solutions (n = 5) and seawater samples (n = 3) were all
Selenium(IV) Antimony, total Arsenic, total Germanium Mass spectrometry Volatile generation Optimization Volatile generation

"Automated Online Preconcentration System For Electrothermal Atomic Absorption Spectrometry For The Determination Of Copper And Molybdenum In Seawater"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 8 Pages 841-847
YU-HSIANG SUNG, ZHEN-SHAN LIU and SHANG-DA HUANG

Abstract: The operation of the flow injection manifold is illustrated diagrammatically, the operating sequence is tabulated, and a diagram of the computer-control connections is also presented. Fourteen samples can be injected per h. Online pre-concentration of the analytes is achieved by incorporation of a bypassable microcolumn of Muromac A-1 chelating resin at the tip of the AS-60 autosampler arm. A diagram of the microcolumn is presented; for the retention of Cu and Mo the resin volumes are ~7 and 4 µL and the mesh sizes are 100-200 and 200-400, respectively. Elution into the graphite furnace is effected with 50 µL of 20% (v/v) HNO3. The heating programmes are tabulated. The metals were determined in seawater by calibration with standard solutions in 0.2% HNO3 carried through the procedure; the detection limits and injection volumes for Cu and Mo were 0.009 and 0.06 µg/l and 606.9 and 200 µl, respectively. The results for Cu in three and for Mo in two seawater standard reference materials agreed well with the certified values.
Copper Molybdenum Spectrophotometry Preconcentration Muromac Resin Reference material Column

"Determination Of Copper, Cadmium, Lead, Bismuth And Selenium(IV) In Sea-water By Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry After Online Separation"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 5 Pages 363-369
Dirce Pozebon, Valderi L. Dressler and Adilson J. Curtius

Abstract: A procedure for the determination of Cu, Cd, Pb, Bi and Se(IV) in seawater by electrothermal vaporization inductively coupled plasma mass spectrometry, after online separation using a flow injection system, is proposed. Matrix separation and analyte pre-concentration. was accomplished by retention of the analytes complexed with the ammonium salt of O,O-diethyldithiophosphoric acid on C18 immobilized on silica in a minicolumn coupled directly to the autosampler arm of the vaporizer. The methanol used as eluent was vaporized after being automatically injected into the graphite tube, prior to the vaporization of the analytes. The conditions for the online complexation and separation as well as the vaporizer temperature program were optimized. The recoveries from seawater were 90-110%. The accuracy of the method was tested by the anal. of 2 certified seawaters, CASS-3 and NASS-4, from the National Research Council of Canada. The concentration. of Bi in these seawaters was below the method detection limit. The relative standard deviation was <10% (n=6). The throughput was 22 samples/h and the volume of sample consumed was only 2.3 mL. Tl and As(III) were also separated but their complexation in seawater was not efficient.
Copper Cadmium Lead Bismuth Selenium(IV) Mass spectrometry Ion pair extraction C18 Silica Preconcentration Reference material

"Determination Of Copper, Manganese And Nickel In Biological Samples And Sea-water By Flow Injection Online Sorption Preconcentration In A Knotted Reactor Coupled With Electrothermal Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 6 Pages 527-531
Elissaveta Ivanova, Karima Benkhedda and Freddy Adams

Abstract: A flow injection system with online sorption pre-concentration of copper, nickel and manganese with ammonium pyrrolidinedithiocarbamate (APDC) or 8-hydroxyquinoline (HQ) in a knotted reactor (KR) coupled with electrothermal atomic absorption spectrometry was developed. APDC offered better performance characteristics than HQ for the pre-concentration of copper and nickel but could not be employed for manganese. The performance characteristics of the determination of copper and nickel with APDC were: detection limits (3s), 6.0 and 7.6 ng L-1, precision (relative standard deviation) 2.5% for 0.2 µg L-1 and 1.5% for 0.2 µg L-1 and enhancement factors 44 and 21 using a 30 s pre-concentration time. The corresponding parameters for the determination of manganese with HQ were detection limit 29.0 ng L-1, precision (relative standard deviation) 2.9% for 0.4 µg-1 manganese and enhancement factor 8 with a 30 s pre-concentration time. The sampling frequency was 26 h-1. The accuracy of the method was demonstrated by the anal. of certified reference materials and by recovery measurements on spiked samples.
Copper Manganese Nickel Spectrophotometry Preconcentration Knotted reactor Tube wall immobilization Reference material 8-Hydroxyquinoline Pyrrolidine dithiocarbamate

"Determination Of Copper, Cadmium, Manganese, And Lead In Saline Water With Flow Injection And Atom Trapping Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 7 Pages 631-634
Lyndon A. Ellis and David J. Roberts

Abstract: A flow injection device has been developed to sep. Cu, Cd, Mn and Pb from a solution of sodium chloride, thus minimizing interference and enabling their accurate determination in high salinity waters such as sea- or estuary water. Micro-columns of Chelex 100 resin were used and parameters of ammonium acetate buffer concentration, pH and the concentration. of a buffer flush have been optimized. Close to 100% recovery of the transition elements and 99.8% exclusion of sodium chloride was achieved. Atom trapping atomic absorption spectrometry (ATAAS) was used as the detection technique to determine concentrations. of the four elements at four sites on the Severn Estuary. In addition, a water cut-off device has been incorporated to improve the safety of the AT app.
Copper Cadmium Manganese Lead Spectrophotometry Interferences Chelex Buffer

"Use Of Flow Injection Cold Vapor Generation And Preconcentration On Silica Functionalized With Methylthiosalicylate For The Determination Of Mercury In Biological Samples And Sea-water By Inductively Coupled Plasma Atomic Emission Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 10 Pages 1167-1171
P. Ca&ntilde;ada Rudner, J. M. Cano Pav&oacute;n, F. S&aacute;nchez Rojas and A. Garc&iacute;a de Torres

Abstract: A novel and expeditious approach to the direct determination of mercury in sea-water and biological samples based on a separation-pre-concentration system coupled online to a flow injection (FI) manifold is described. The method employs online pre-concentration of mercury on a 3 cm x 3 mm column packed with silica gel functionalized with methylthiosalicylate (TS-gel) and placed in the injection valve of the FI manifold. Synthesis of the resin is simpler and faster than that of other resins described previously, where many steps are required. In this system the metal was eluted from the column with thiourea and mixed online with NaBH4; mercury vapor was generated directly and separated via a gas-liquid separator. Various parameters and chemical variables affecting the pre-concentration of Hg(II), the direct generation of mercury vapor and the final determination by ICP-AES were evaluated. The calibration graph was linear over the range 5-1000 ng mL-1 Hg(II), with a relative standard deviation at the 10 ng mL-1 level of 2.1%. The accuracy of the method was evaluated by the analysis of certified reference materials. The results showed good agreement with the certified values.
Mercury Spectrophotometry Silica gel Preconcentration Volatile generation Reference material Phase separator Optimization

"Completely Integrated Online Determination Of Dissolved Selenium(IV) And Total Inorganic Selenium In Sea-water By Flow Injection Hydride Generation Atomic Fluorescence Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 11 Pages 1291-1296
Youzhao He, Hamdi El Azouzi, M. Luisa Cervera and Miguel de la Guardia

Abstract: Highly sensitive online pre-treatment methods were developed for the direct determination of trace amounts of selenite and total inorganic Se in seawater. Selenite determination was carried out on samples acidified with HCl and merged online with 5% (m/v) KH2PO4, which was used as an interference eliminating reagent. For total inorganic Se determination, acidified samples were merged with 30% (m/v) NaBr, used for reduction of Se(VI), pre-reduced online by microwave irradn. at 210 W for 60 s. After pre-treatment, the sample zone was stored in a coil and then transported at a flow rate of 22 mL/min for reaction with 1.5% (m/v) NaBH4. The hydride produced was separated and dried and Se was determined in a mini-hydrogen diffusion flame by non-dispersive atomic fluorescence spectrometry. The interface developed for this purpose makes possible the integration, within the same manifold, of 2 steps involving very different reaction times. The detection limits were 5 ng/L for Se(IV) and 4 ng/L for total inorganic Se. The recoveries of selenite at the 30 ng/L level were 94-104% and those of total inorganic Se, at the same concentration. level, were 92-98%. These methods are suitable for the accurate and direct anal. of natural waters, and the results obtained for total inorganic Se determination in a freshwater reference material were in good agreement with the certified value.
Selenium(IV) Selenium, inorganic Fluorescence Sample preparation Reference material Interferences Microwave Online digestion

"Direct Determination Of Trace Metals In Sea-water By Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 11 Pages 1239-1244
Eivind Rosland and Walter Lund

Abstract: The direct determination of trace metals in seawater by inductively coupled plasma mass spectrometry (ICP-MS) is described, based on sample introduction by flow injection analysis (FIA) and electrothermal vaporization (ETV). FIA-ICP-MS was used for the determination of Mn, Mo and U; 500 µL of 1+9 diluted seawater were injected in a carrier stream of 0.028 mol/L HNO3. The detection limits were 0.7 µg/L Mn, 1.4 µg/L Mo and 0.10 µg/L U. ETV-ICP-MS was used for the determination of Cd and Pb. The analytes were vaporized as chlorides at 800°C, without interference from the matrix elements. The detection limits were 4.1 ng/L for Cd and 0.8 ng/L for Pb. The FIA-ICP-MS and ETV-ICP-MS results were validated by analyzing a reference seawater sample (NASS4).
Manganese Molybdenum Uranium Mass spectrometry Interferences Reference material Method comparison

"Determination Of Technetium In Seawater Using Ion Exchange And Inductively Coupled Plasma Mass Spectrometry With Ultrasonic Nebulization"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 9 Pages 875-878
Ahmet E. Eroglu, Cameron W. Mcleod, Kinson S. Leonard and David Mccubbin

Abstract: An enrichment-separation scheme employing a strong-base type anion-exchange resin was developed for the determination of99Tc in sea-water by inductively coupled plasma mass spectrometry utilising ultrasonic nebulisation with membrane desolvation. Samples were processed through an anion-exchange column to enrich Tc and to eliminate sea-water matrix ions. The limit of detection for 99Tc in sea-water based on processing a 14 mL sample was 0.03 ng l-1. Accuracy was verified with spike recovery experiments. The potential for rapid on-line sample processing via a microcolumn-flow injection system was demonstrated.
Technetium Ion exchange Mass spectrometry Nebulizer

"Determination Of Reactive Silicate In Seawater By Flow Injection Analysis"
Anal. Chem. 1983 Volume 55, Issue 14 Pages 2378-2382
Jens Thomsen, Kenneth S. Johnson, and Robert L. Petty

Abstract: Flow injection analysis was used to automate the determination of silicate In natural waters by the molybdenum blue method. The analysis rate Is 80 per hour when a continuous stream of seawater Is analyzed. Thirty discrete samples can be analyzed in duplicate per hour. The relative precision was better than 1% for silicate concentrations above 10 pM. A detection limit of 0.5 pM Si was achieved. The refractive index interference has been eliminated. This allows a low detection limit to be obtained for a wide range of salinities. A lower detection limit of 0.1 pM SI can be obtained with longer reaction coils and a lower sampling rate. There is a small salt effect and little interference from phosphate. The method was tested on an oceanographic cruise from Monterey Bay (Callfornia) to San Francisco Bay.
Silicate Spectrophotometry

"Determination Of Phosphate In Seawater By Flow Injection Analysis With Injection Of Reagent"
Anal. Chem. 1982 Volume 54, Issue 7 Pages 1185-1187
Kenneth S. Johnson and Robert L. Petty

Abstract: A modification of flow Injection analysis is described that can increase the sensitivity of an analysis. The technique was tested by using it for the determination of dissolved phosphate in seawater with the colorimetric phosphomolybdate complex method. The precision of the method is 1.5% at the 3 µM level, and the detection limit is 0.05 µM. Samples can be analyzed at rates exceeding 90 samples per hour.
Phosphate Spectrophotometry Reverse

"Automated Flow Injection Phenol Red Method For Determination Of Bromide And Bromide Salts In Drugs"
Anal. Chem. 1986 Volume 58, Issue 2 Pages 322-326
Paraskevi I. Anagnostopoulou and Michael A. Koupparis

Abstract: The chloramine T - phenol red method was optimized by the simplex technique. The calibration graph was rectilinear from 1 to 10 mg l-1, with a coefficient of variation (n = 10) from 0.2 to 2.5% at the highest and lowest levels, respectively, and a detection limit of 90 µg l-1. Interference from Cl- and NaHCO3 was eliminated (up to 40 and 10 g l-1, respectively), and that of NH3 was decreased (tolerance limit 25 mg l-1). Glucose, starch, talc (each at 10 g l-1), Carbowax 4000, Mg stearate, Na dodecyl sulfate (each at 1 g l-1), and gelatin (0.5 g l-1) also do not interfere. Ions that react with Chloramine T, Br- or the Br2 produced during the reaction interfere, as do sulfonamides, isoniazid, salicylates, imipramine and propranolone hydrochlorides, and almost all organic substances with a nucleophilic substituent on the phenyl group. Interfering compounds having an acidic or basic functional group can be removed online by Amberlite XAD-2 resin. Recoveries of 2.5 to 5 mg L-1 of Br- added to seawater were from 98.6 to 103.3% and from serum samples spiked with 19.6 to 103 mg L-1 they were from 97.2 to 103%. In the analysis of eight commercial drugs, recoveries by the proposed method agreed well with those by the USP XX 1980 method. Up to 120 measurements h-1 can be performed.
Drugs Bromide Clinical analysis Spectrophotometry Amberlite Interferences Simplex

"Determination Of Picomolar Levels Of Cobalt In Seawater By Flow Injection Analysis With Chemiluminescence Detection"
Anal. Chem. 1987 Volume 59, Issue 14 Pages 1789-1794
Carole M. Sakamoto-Arnold and Kenneth S. Johnson

Abstract: Interfering alkaline-earth ions were separated from Co in seawater online on a column of immobilized quinolin-8-ol on Fractogel; elution of Co was with 0.05 M HCl. The eluate was mixed with reagent streams containing 0.02 M gallic acid, 0.4 M H2O2, 0.15 M NaOH and 4% methanol before chemiluminescence detection at 643 nm. The detection limit was ~8 pM, the analysis time was 8 min, and the average standard deviation (n ~ 80) was 5%.
Cobalt Chemiluminescence Interferences 8-Hydroxyquinoline Column Immobilized reagent Preconcentration

"Membrane Gas-liquid Separator For Flow Injection Hydride-generation Atomic Absorption Spectrometry"
Anal. Chem. 1987 Volume 59, Issue 19 Pages 2446-2448
Manabu Yamamoto, Kazuko Takada, Takahiro Kumamaru, Makoto Yasuda, Shozo Yokoyama, and Yuroku Yamamoto

Abstract: A flow injection manifold with a membrane tube gas - liquid separator (illustrated) was applied in the determination of As in seawater. Thus, KI, HCl and ascorbic acid solution were added to the sample before injection of an aliquot (1 ml) into a stream of 1 M HCl and air (each 5 mL min-1). After being mixed with streams of Ar (100 mL min-1) and NaBH4 solution (3%; 1.5 mL min-1), the combined stream was passed through a micro-porous PTFE tube (o.d. 4 mm; i.d. 3 mm) inside a borosilicate glass tube (25 cm x 8 mm). The gaseous AsH3, H and Ar diffused through the PTFE tube walls and were passed to a heated silica cell at 950°C for the determination of As (Ibid., 1985, 57, 1382). In the determination of 3 ppb of As, the coefficient of variation was 2.5% (n = 10). There was little interference from up to a 2000- or 50,000-fold excess, respectively, of Pt or Ni.
Arsenic Spectrophotometry Gas diffusion Interferences Teflon membrane

"Separation Of Trace Metal Complexes For Analysis Of Samples Of High Salt Content By Inductively Coupled Plasma Mass Spectrometry"
Anal. Chem. 1989 Volume 61, Issue 2 Pages 149-153
Michael R. Plantz, James S. Fritz, Fred G. Smith, and R. S. Houk

Abstract: Solutions of trace metals (Au, Bi, Co, Cr, Cu, Fe, Hg, Mo, Nb, Ni, Pt, Tl, U and V) in aqueous media of high salt content were treated with bis(carboxymethyl)dithiocarbamate reagent (prep. described) and injected into the loading solvent (0.05 M formate buffer of pH 3.25) for application to a column of Amberlite XAD-4 resin. The adsorbed complexes were eluted with aqueous 0.1 M NH3 (pH 11) and the eluate was analyzed by ICP-MS on a Sciex Elan model 250 instrument fitted with a continuous-flow ultrasonic nebulizer. Detection limits in salt-rich aqueous solution ranged from 6 ng L-1 for Bi to 80 ng L-1 for Pt. The method has been used to determine Cr, Ni and Pt in urine, and trace metals in seawater.
Chromium Nickel Platinum Mass spectrometry Column Instrumentation Nebulizer Amberlite Preconcentration Complexation Buffer

"Determination Of Sub-nanomolar Levels Of Iron(II) And Total Dissolved Iron In Seawater By Flow Injection Analysis With Chemiluminescence Detection"
Anal. Chem. 1991 Volume 63, Issue 9 Pages 893-898
Virginia A. Elrod, Kenneth S. Johnson, and Kenneth H. Coale

Abstract: The flow injection manifold used was similar to that described previously (Sakamoto-Arnold and Johnson, ibid., 1987, 59, 1789) for Co in seawater with the addition of a column containing 8-hydroxyquinoline (I) on Fractogel. Seawater was collected in acid-washed polyoxyethylene bottles and acidified to pH 5.5. The sample was drawn through a PTFE filter (0.45 µm) and pumped (1.1 mL min-1) on to the I column for 4 min. The injection valve was switched to the 'elute' position and the Fe was eluted from the column with 75 mM HCl (1.1 mL min-1) for 1 min. The eluate stream merged with the 1 mM brilliant sulfoflavin stream (pH 8.3; 2.3 mL min-1) and then with the 2% H2O2 straem (2.3 mL min-1) before entering the flow cell. The flow cell comprised a clear PVC tube (50-cm coil) in a grey PVC housing maintained at -20°C. Light generated by the chemiluminescent reaction was detected by a photomultiplier tube connected to a photometer and a computer. Other metals did not interfere at concentration. expected in seawater. Detector response was rectilinear from 1 to 1000 nM Fe(II). The detection limit was 0.45 nM Fe(II). Calibration graphs were rectilinear at 2.5 nM Fe(II) only if peak areas were measured. Results agreed well with the certified values for reference materials.
Iron(2+) Iron Chemiluminescence Column Computer Interferences pH Flowcell Reference material 8-Hydroxyquinoline

"Determination Of Manganese In Seawater Using Flow Injection Analysis With Online Preconcentration And Spectrophotometric Detection"
Anal. Chem. 1992 Volume 64, Issue 22 Pages 2682-2687
Joseph A. Resing and Michael J. Mottl

Abstract: The method was based on measurement of the absorbance of a solution of malachite green (I) formed by the Mn(II)-catalyzed reaction of KIO4 with leucomalachite green (II). The sample was was pre-concentrated on a column (7 cm x 3.2 mm) containing quinolin-8-ol immobilized on a vinyl polymer gel (Landing et al., Ibid., 1986, 58, 3031) which was rinsed with Tris buffer at pH 7.8 before elution of the Mn with 36 mM HCl which was then mixed in a 1-m coil with a stream of a solution containing 6 M HCl and II. Streams of 10 mM KIO4 and 2 M NH4+ acetate buffer at pH 4.15 were mixed in a 1-m coil and then mixed with the Mn-containing mixed streams in a 10 m coil at 50°C before measurement of the I solution absorbance at 620 nm. The mixing coils were constructed from knitted Teflon tubing (0.5 mm i.d.). The system also contained a second resin column which was loaded while the first column was eluted. Calibration graphs were rectilinear and parabolic for 25 pM to 0.5 nM and 0.5 to 20 nM of Mn(II), respectively; the detection limit was 36 pM-Mn(II). In the determination of 404 pmol kg-1 of Mn(II) in NASS-2 seawater the coefficient of variation were 5.4%. There was no significant interference from Co, Cu, Ni, Zn, Fe and I- at concentration. twenty-fold higher than their oceanic values. A method for the rapid determination of dissolved Mn in seawater uses online concentration of Mn(II) onto 8-hydroxyquinoline immobilized on a vinyl polymer gel. The Mn(II) is then eluted from the gel by acid and its concentration. determined by spectrophotometric detection of the malachite green formed from the reaction of leucomalachite green and KIO4 with Mn(II) acting as a catalyst. The limit of detection is 36 pmol/L when concentrating 15 mL of seawater. The accuracy of the method was tested using NASS-2 standard seawater. The method has a precision of ~5% for Mn(II) concentrations of ~400 pmol/L. Analysis time is ~5.5 min/sample.
Manganese Spectrophotometry Knotted reactor Reference material 8-Hydroxyquinoline Interferences Resin Preconcentration

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

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

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

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

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

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

"Determination Of Zinc In Seawater Using Flow Injection Analysis With Fluorimetric Detection"
Anal. Chem. 1994 Volume 66, Issue 17 Pages 2732-2738
Jocelyn L. Nowicki, Kenneth S. Johnson, Kenneth H. Coale, Virginia A. Elrod, and Steve H. Lieberman

Abstract: Seawater was injected at 1.1 ml/min for 4 min onto a 35 µL cation-exchange PTFE column (4 cm x 1.5 mm i.d.) containing 8-hydroxyquinoline immobilized on Fractogel. The column was washed with 1.1 mL water, Zn was eluted with 1.1 mL 0.08 M HCl, mixed with 40 µM-p-tosyl-8-aminoquinoline reagent/0.1 M sodium tetraborate buffer and detected fluorimetrically at 495 nm (excitation at 377 nm). The calibration graph was linear for 0-500 nM-Zn with a detection limit of 0.01 nM-Zn. Only Cd interfered so that a correction was necessary at higher than usual Cd levels.
Zinc Fluorescence Interferences 8-Hydroxyquinoline

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

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

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

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

"Fluorimetric Determination Of Al In Seawater By Flow Injection Analysis With Inline Preconcentration"
Anal. Chem. 1994 Volume 66, Issue 22 Pages 4105-4111
Joseph A Resing and C. I. Measures

Abstract: A highly sensitive method for the shipboard determination of A1 in seawater by flow injection analysis (FIA) has been developed. The method employs in-line pre-concentration of A1 onto a column of resin-immobilized 8-hydroxyquinoline. The AI is subsequently eluted into the FIA system from the resin with acidified seawater. The eluted AI reacts with lumogallion to form a chelate, which is detected by its fluorescence. The fluorescence is enhanced -5-fold by the addition of a micelleforming detergent, Brij-35. The method has a detection limit of -0.15 nM and a precision of 1.7% at 2.4 nM. The method has a cycle time of -3 min and can be readily automated. The speed, ease of use, and relative freedom from contamination artifacts makes this method ideal for shipboard determination of AI in seawater.
Aluminum Fluorescence Preconcentration

"Chemiluminescence Detection Of Red Tide Phytoplankton Chattonella Marina"
Anal. Chem. 1995 Volume 67, Issue 1 Pages 225-228
Tsai-yun Lee, Naohiro Gotoh, Etsuo Niki, Kenji Yokoyama, Mikio Tsuzuki, Toshifumi Takeuchi, and Isao Karube

Abstract: A sensitive method was developed for monitoring the cell concentration of red tide phytoplankton Chattonella marina, which frequently caused fish death via an obscure mechanism. 2-Methyl-6-(p-methoxyphenyl)-3,7- dihydroimidazo[ 1,2-alpyrazin-3-one (MCIA), a Cypyridina luciferin analog, which emits light strongly at 465 nm in the presence of superoxide, was applied as a chemiluminescence probe. The MCIA-dependent chemiluminescence of room-cultured axenic C. marina was efficiently suppressed by adding superoxide dismutase (20 units mL-l) to the phytoplankton suspension but not by filtering out the plankton cells, indicating the chemiluminescence was due to the superoxide released from C. marina. Several species of other tested phytoplankton, such as Heterosigma akashiwo, Skeletonema costatum, Chaetoceros sociale, and Porphyridium cruentrum did not induce this chemiluminescence whereas Chattonella antiqua showed characteristic similar to C. marina, suggesting that this method has specificity for the Chattonella genus. As compared with the cell density of C. marina during the red tide seasons, the detection limit of 200 cells mL-' based on this luminescent method is considered to be applicable for C. marina detection in the early stage of its red tides.
Phytoplankton, chattonella marina Chemiluminescence

"Online Standard Addition Method With ICP-MS Using Flow Injection"
Anal. Chem. 1995 Volume 67, Issue 9 Pages 1553-1557
Diane Beauchemin

Abstract: A Perkin-Elmer SCIEX ELAN 500 instrument fitted with a mass flow controller, a PlasmaTherm torch and a translational stage for the torch box was used in conjunction with a single-line flow injection manifold in which a peristaltic pump controlled the flow of carrier to a sample injection valve connected to the Meinhard nebulizer by PTFE tubing. Operating conditions used to determine trace metals in 1% HNO3/0.01 M K medium and in standard seawater are tabulated. Initially, 1% HNO3 was used as carrier, into which a multi-element or single-element standard was injected. After rinsing of the loop, the sample was injected. The standard was then used as carrier for a further injection of sample. To minimize rinsing time, for the next run the sample was injected first into the standard carrier and then into the blank carrier, after which the standard was injected into the blank carrier. Sample consumption was reduced, a matrix-matched blank was not necessary, and sensitivity was close to that with continuous sample nebulization. However, precision was poorer than that of peak height calibration. The method was used to determine Mo in standard seawater. A single-line flow injection manifold was used to perform the standard addition method online with ICPMS. The proposed approach requires injection of the sample into two different carriers (i.e., a blank and a standard with a greater concentration than that of the sample), as well as injection of the standard in the blank carrier. The method takes into account the change in sensitivity induced by the sample upon its injection into the standard carrier. In the best conditions, one replicate multielemental analysis by the online standard addition method was accomplished in 200 s (using 100 mL injections). Furthermore, the setup induced only limited dispersion (i.e., the dispersion coefficient was between 1.2 and 2) and therefore provided sensitivity similar to that expected from direct continuous nebulization of the sample. Although precision was poorer than that which is typical of, for instance, external calibration, the proposed method adequately compensated for the effect of a 0.01 M K matrix, allowing the accurate determination of V, Co, Ni, Cu, Zn, Mo, Cd, Sb, and Pb in this matrix. The method was also successfully applied to the direct determination of Mo in seawater. Copyright 1995, American Chemical Society.
Metals, heavy Antimony Cadmium Cobalt Copper Lead Molybdenum Nickel Vanadium Zinc Mass spectrometry Reference material Standard additions calibration

"Microscale Flow Injection And Microbore High Performance Liquid Chromatography Coupled With Inductively Coupled Plasma Mass Spectrometry Via A High-efficiency Nebulizer"
Anal. Chem. 1995 Volume 67, Issue 24 Pages 4530-4535
Spiros A. Pergantis, Edward M. Heithmar, and Thomas A. Hinners

Abstract: A high-efficiency nebulizer has been used for coupling microscale now injection and microbore high performance liquid chromatography with inductively coupled plasma mass spectrometry (ICPMS). The microscale now injection system was configured to minimize band broadening between the injection valve and the nebulizer, and it was evaluated for now rates between 20 and 120 µL/min. Various materials, including certified reference materials, were analyzed for their arsenic and lead contents, Separation of arsenic species was carried out on microbore liquid chromatography columns. The absolute detection limits (femtogram range) for various arsenic compounds were excellent compared with those obtained previously by using conventional column (1 mL/min eluent now) high performance liquid chromatography/inductively coupled plasma mass spectrometry, Other advantages of this system include use of small sample volumes (less than or equal to 1 µL), the resulting minimization of sample matrix introduction into the plasma, and reduced waste generation compared with conventional ICPMS sampling systems. (31 references)
Arsenic Lead HPLC Mass spectrometry Optimization Reference material Simplex Speciation

"Solenoid Pumps For Flow Injection Analysis"
Anal. Chem. 1996 Volume 68, Issue 15 Pages 2717-2719
Debra A. Weeks and and Kenneth S. Johnson

Abstract: The peristaltic pump of a typical FIA system was replaced by three solenoid-driven diaphragm pumps with integral Viton check valves. These pumps had the ability to incorporate microprocessor control of the reagent and sample streams independently. The system was tested by the determination of nitrite in water and seawater. Reduced detector oscillations were achieved with a 140 µL flow cell, a 1 m reaction coil and a 100 µL injection loop. Detection limits were M-nitrite, the RSD was 1% for 10 µM-nitrite and 60 injections/h were possible with flow rates of 0.5 ml/min for reagents and sample. These values match the performance of the conventional FIA system.
Nitrite

"Separation Of Heavy Metals, In Particular Uranium, From Seawater By Use Of Anchor Groups Of High Selectivity. 2. Continuous-flow In A Fluidized Bed"
Fresenius J. Anal. Chem. 1982 Volume 313, Issue 4 Pages 289-296
K. H. Lieser and B. Gleitsmann

Abstract: The separation of the trace elements Fe, Ni, Cu, Zn and U from sea water in a fluidized bed of Hyphan on bead cellulose and Hyphan on polystyrene is studied in parallel experiments during a period of 8 months. Samples from the incoming water and from the exchangers are taken from time to time for determining the trace element content. The loading curves are presented and discussed.At the beginning the trace elements are taken up quantitatively by Hyphan on bead cellulose whereas about one half or less is fixed on Hyphan on polystyrene. This is due to the fast exchange on bead cellulose and the slow exchange on polystyrene.
Copper Iron Lead Nickel Uranium Zinc

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

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

"Determination Of Ultratrace Concentrations Of Elements By Means Of Online Solid Sorbent Extraction Graphite Furnace Atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1992 Volume 343, Issue 9-10 Pages 754-755
Michael Sperling, Xuefeng Yin and Bernhard Welz

Abstract: Solid sorbent extraction using a microcolumn in an automated system was successfully coupled with a graphite furnace for atomic absorption spectrometry. Bonded silica with octadecyl functional groups (C-18 reversed phase material) was used in a 15 µL conically shaped microcolumn as a sorbent for the metal complexes formed online with Na diethyldithiocarbamate. Column elution was performed with an EtOH eluent into a PTFE capillary used for eluate storage and transfer into the graphite tube. With a sample loading time of 60 s and direct introduction of the eluate portion containing the highest analyte concentration. into the graphite tube, an enrichment factor of ~20 was realized. Effective elimination of contamination by the closed system and online purifn. of the complexing agent together with highly selective separation of trace metals from alkaline and earth alkaline elements allowed the determination of ultratrace metals in seawater and deionized water. Using only 3 mL of sample, detection limits for Cd, Co, Cu, Pb, and Ni of 0.8, 12, 17, 6.5, and 36 ng/L, respectively, was achieved.
Cadmium Cobalt Copper Lead Nickel Spectrophotometry Sample preparation C18 Preconcentration Ultratrace Solid phase extraction

"Antimony(III) And Antimony(V) Separation And Analytical Speciation By A Continuous Tandem Online Separation Device In Connection With Inductively Coupled Plasma Atomic-emission Spectrometry"
Fresenius J. Anal. Chem. 1995 Volume 353, Issue 2 Pages 128-132
A. Men&eacute;ndez Garc&iacute;a, M. C. P&eacute;rez Rodr&iacute;guez, J. E. S&aacute;nchez Uria and A. Sanz-Medel

Abstract: For Sb(III) determination a stream of sample (0.75 ml/min) mixed with 0.2 M ammonium citrate/NaOH buffer solution of pH 6 was merged with a stream (0.7 ml/min) of 0.1% pyrrolidine-1-dithiocarboxylic acid ammonium salt and the resulting stream (1.45 ml/min) then merged with IBMK (0.5 ml/min) at a solvent segmenter. Extraction took place in an extraction coil (270 cm x 0.7 mm i.d.) and the consecutive organic and aqueous segments were separated at a membrane phase separator. The aqueous phase as collected for Sb(V) determinations and the organic phase was mixed with glacial acetic acid (1 ml/min) and 2% sodium tetrahydroborate in DMF (0.5 ml/min) for stibine generation. The stibine formed was transferred to the ICP torch by Ar (0.3 l/min) and Sb was monitored at 217.58 nm. For Sb(V) determination the aqueous phase collected above was acidified with HCl to give a final concentration of 3 M HCl and mixed with 2% KI. The resulting solution was used for hydride generation ICP-AES with 1% NaBH4. The calibration graph was linear up to 100 µg/ml with detection limits of 3 ng/ml of Sb(III) and 8 ng/ml of Sb(V). RSD (n = 10) were 4% for 100 ng/ml Sb(III) and 5% for 100 ng/ml Sb(V). Interferences by ions found in sea and estuarine water was tabulated and discussed. The method was applied to Sb determination in seawater.
Antimony(3+) Antimony(5+) Spectrophotometry Speciation Interferences Volatile generation MIBK Phase separator Volatile generation

"Online Column Preconcentration For The Determination Of Cobalt In Seawater By Flow Injection Chemiluminescence Detection"
Fresenius J. Anal. Chem. 1996 Volume 355, Issue 5-6 Pages 676-679
Shizuko Hirata, Yukimasa Hashimoto, Masato Aihara and G. Vitharana Mallika

Abstract: Seawater (100 ml) was adjusted to pH 3.6 with 0.5 mL formic acid/ammonium formate buffer then passed through a fluoride-containing metal alkoxide glass column (3 cm x 4 mm i.d.) of 8-quinolinol immobilized on silica gel for 2 min at a flow rate of 3 ml/min, with 0.05 M HCl as carrier stream at a flow rate of 1.7 ml/min. Most heavy metals were separated except Fe(III), but it did not interfere when the gallic acid/H2O2 method was used: water was passed through the column to remove alkali and alkaline earth metals, then the eluate was passed in the reverse direction at a flow rate of 1.7 ml/min and mixed with gallic acid and NaOH both flowing at 0.76 ml/min. The mixture was heated to 60°C in a 2 m reaction coil and the chemiluminescence intensity was measured. The calibration graph was linear from 0.6 ng/l to 1 µg/l Co. The detection limit was 0.62 ng/l Co for a 6 mL sample; RSD was 2.1% (n = 10) for 10 ng/l Co(II). Results from the analysis of reference seawater samples agreed with the certified values.
Cobalt Chemiluminescence Interferences Reference material Preconcentration Silica gel Heated reaction

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

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

"Sequential Flow Analysis Coupled With ACSV For Online Monitoring Of Cobalt In The Marine Environment"
Fresenius J. Anal. Chem. 1997 Volume 358, Issue 6 Pages 703-710
Anne Daniel A, Alex R. Baker A, C. M. G. van den Berg

Abstract: The development of a compact instrument for on-line measurement of trace metals in seawater is described. The system is based on adsorptive cathodic stripping voltammetry (ACSV), and on the concept of sequential flow analysis, to perform on-line measurements with controlled perturbation of natural equilibria of the element. The design combines a low volume flow cell with a miniature solenoid pump and valves to achieve low power consumption. The flow segmentation is time-controlled and the detection step takes place in a well-defined part of the flow stream where reagent and sample occur mixed. The system was tested on the determination of cobalt in seawater but it is likely that the same technique can be used to determine other metals detectable by CSV. The determination range was 6-1050 pmol/L cobalt with a detection limit (3σ) of 6 pmol/L. The measurement rate was about 60 h-1. Comparative measurements were carried out using continuous flow analysis. The apparatus was used continuously on board a ship to determine the distribution pattern of cobalt in surface waters off the coast of California.
Cobalt Voltammetry Voltammetry Sequential injection

"Speciation Of Antimony By Atomic Absorption Spectrometry. Applicability To Selective Determination Of Antimony(III) And Antimony(V) In Liquid Samples And Of Bioavailable Antimony In Sediments And Soil Samples"
Microchim. Acta 1992 Volume 109, Issue 1-4 Pages 149-155
Mar&iacute;a Beatriz de la Calle Gunti&ntilde;as, Yolanda Madrid and Carmen C&aacute;mara

Abstract: Speciation of Sb(III) and Sb(V) by AAS in liquid samples was evaluated by investigating the (i) determination of Sb(III) and SbV in water by selective extraction with lactic acid - malachite green by graphite-furnace AAS; (ii) determination of Sb(III) and Sb(V) by hydride-generation - AAS coupled to flow injection, batch and continuous-flow systems; (iii) mineralization methods for soil samples. Different sample pre-treatments were evaluated in terms of recovery of total Sb and the ability to speciate Sb(III) and SbV by slurry formation in soil and sediments. The graphite-furnace extraction method was the most convenient method for speciation of Sb(V) and Sb(III) in surface and seawater.
Antimony(3+) Antimony(5+) Spectrophotometry Spectrophotometry Speciation Slurry

"Microchemical Determination Of Iodate And Iodide In Sea-waters By Flow Injection Analysis"
Microchim. Acta 1993 Volume 110, Issue 1-3 Pages 71-77
Koichi Oguma, Kazuyuki Kitada and Rokuro Kuroda

Abstract: Filtered seawater samples were diluted to a salinity of 1.2%. The total inorganic iodine (i.e. IO3- and I-) was determined by injecting the diluted samples (128 µL) into a carrier stream of aqueous 2% NaCl. The sample stream was merged with a flow of 50 mM ammonium ferric sulfate solution in 4.6 M HNO3. The stream then merged with a stream of 2.4 mM KSCN - 1.5 mM NaNO2 before passing through a reaction column at 50°C. The absorbance of the column effluent was monitored at 460 nm. Determination of IO3- was effected by passing the sample carrier stream through a Bio-Rad AG1-X4 anion-exchange resin column (10 cm x 0.5 mm) to remove I- before repeating the above procedure. Recoveries were >97% and the coefficient of variation was 1.3%. The method was applied to seawater samples with a total iodine content ranging from 0.75 to 150 ng mL-1. Results are presented.
Iodate Iodide Spectrophotometry Resin Biorad

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

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

"Speciation Of Mercury By Continuous-flow Liquid-liquid Extraction And Inductively Coupled Plasma Atomic-emission Spectrometry Detection"
Microchim. Acta 1996 Volume 122, Issue 3-4 Pages 157-166
A. Men&eacute;ndez Garc&iacute;a, M. L. Fern&aacute;ndez S&aacute;nchez, J. E. S&aacute;nchez Ur&iacute;a and A. Sanz Medel

Abstract: The method was based on continuous liquid-liquid extraction of methylmercury into xylene as its bromide followed by cold Hg-vapor hydride-generation ICP-AES. A diagram of the flow manifold is given. Sample of pH 6.5 (0.75 ml/min) was merged with 0.3 M KBr (0.5 ml/min) and passed through a mixing coil (100 cm) before merging with xylene (0.5 ml/min). After passage through an extraction coil (380 cm x 0.7 mm i.d.) the organic and aqueous phases were separated using a PTFE membrane. The organic phase merged with glacial acetic acid (1 ml/min) and 3.5% NaBH4 in DMF (0.7 ml/min) and the Hg vapor formed was transferred to the ICP in Ar (0.3 l/min) for determination of Hg by AES at 253.65 nm. The ICP parameters are tabulated. Inorganic Hg was determined in the aqueous phase by hydride-generation AES after acidification and reaction with 1% NaBH4. The detection limit for methylmercury was 4 ng/ml as Hg and that for inorganic Hg was 2 ng/ml. The calibration graph was linear up to 100 µg/ml methylmercury and the RSD for 100 ng/ml methylmercury (n = 10) was 5%. The sampling frequency was 10^-12/h. The method was applied to seawater and urine.
Mercury Methylmercury ion Spectrophotometry Sample preparation Speciation Solvent extraction Teflon membrane

"Indirect Determination Of Iodine In Seawater And Brine By Atmospheric-pressure Helium Microwave Induced Plasma Atomic Emission-spectrometry Using Continuous-flow Cold Vapor Generation Of Mercury"
Microchem. J. 1990 Volume 41, Issue 2 Pages 148-155
Taketoshi Nakahara* and Tamotsu Wasa

Abstract: The method was based on the decrease of the Hg emission intensity in highly acidic solution due to the formation of Hg(II) - iodide complexes. The reductant, 0.02% SnCl2 in 0.1 M HCl and Hg(II) in 4 M HNO3 (10 ng mL-1) were added to the sample solution containing I- and the decrease in the Hg signal at 253.652 nm was measured. In the analysis of seawater and brine, IO3- was reduced to I- with 0.001% ascorbic acid. The response was rectilinear from 2 to 100 ng mL-1; limit of detection was 0.74 ng mL-1. The coefficient of variation (n = 100) for 50 ng mL-1 was 1.05%. Mean recoveries were >93%.
Iodine Spectrophotometry Detection limit Indirect Volatile generation Volatile generation

"Flow Injection Online Sorbent Extraction Preconcentration And Separation For Flame And Graphite-furnace Atomic Absorption Spectrometry"
Microchem. J. 1992 Volume 45, Issue 2 Pages 163-177
Bernhard Welz

Abstract: A review with 33 references is presented that includes diagrams of the relevant systems. Significant progress has been made recently in online pre-concentration of trace elements for flame (FAAS) and graphite furnace atomic absorption spectrometry (GFAAS) by the use of solid sorbents. The use of microcolumns which were eluted in a direction opposite to the direction of sample loading, and an overall optimization of the system made it possible to increase efficiency and sampling rate substantially. Enrichment factors of 20-25 could be achieved with only 20 s loading time so that the sampling frequency could be increased to 120/h, a value which is compatible with routine FAAS operation. Online coupling of sorbent extraction pre-concentration with GFAAS was found to provide a number of important advantages. A 20 to 25-fold increase in sensitivity was typically obtained with 1 min pre-concentration, using eluate zone sampling for the most efficient analyte transfer into the graphite tube. An effective separation of the analyte element from interfering matrix components could be achieved using carefully designed wash steps between sample loading and elution. This resulted in detection limits for a number of trace elements which were essentially identical for pure solutions and samples with a high total salt content such as seawater. Finally, sorbent extraction could be used to pre-concentrate selectively one oxidation state of elements occurring in more than one valency, providing a means of speciation which is particularly attractive because of its speed of operation. Total analyte element concentrations could be determined after online or off-line reduction or oxidation of the other valency states. A review with 33 references.
Spectrophotometry Spectrophotometry Sample preparation Review Solid phase extraction Preconcentration Optimization Interferences Speciation Zone sampling

"Determination Of Ultratrace Amounts Of Copper And Cadmium In Seawater By Graphite Furnace Atomic Absorption Spectrometry With Flow Injection Semi Online Preconcentration"
Microchem. J. 1993 Volume 48, Issue 3 Pages 326-342
Wang M. H., Yuzefovsky A. I. and Michel R. G.

Abstract: Methods are described for the determination of ultratrace amounts of copper and cadmium in seawater by graphite furnace atomic absorption spectrometry with flow-injection, microcolumn pre-concentration. A new type of C18 column loaded with sodium diethyldithiocarbamate (sodium-DDC) was used to extract copper and cadmium from seawater as the DDC chelates. The analytical effects of the pH of the mixture of the sample and sodium-DDC solutions and the concentration of the chelating reagent were studied. Sodium-DDC-loaded columns and unloaded C18 columns with different shapes and volumes were compared. To determine copper in seawater, a simple aqueous calibration was made with a mixture of palladium and magnesium nitrate as a matrix modifier, while for cadmium no matrix modifier was necessary. This method required only small seawater volumes, 600 and 400 µl for the determination of copper and cadmium respectively, with pre-concentration factors of 15-fold for copper and 10-fold for cadmium. Detection limits for the pre-concentration of aqueous solutions of copper and cadmium were 0.024 and 0.004 µg liter-;1 (3s), respectively. Results for determinations of copper and cadmium in National Research Council of Canada, CASS-2, Nearshore Seawater Reference Material showed no significant differences between the certified values and the measured values, based on Student's t test at the 95% confidence level. The relative standard deviations of the various measurements varied between 2 and 8%.
Copper Cadmium Spectrophotometry Preconcentration Ultratrace

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

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

"Determination Of Organophosphorus And Carbamate Insecticides By Flow Injection Analysis"
Anal. Biochem. 1992 Volume 200, Issue 1 Pages 187-194
Satish Kumaran* and C. Tran-Minh

Abstract: For determination of the cited groups of insecticides, substrate solution (0.5 mM acetylcholine in 2.5 mM HEPES buffer solution of pH 8.0 containing 20 mM MgCl2, 100 mM NaCl and 0.01% of gelatin; 250 µL) was injected into a carrier stream (0.45 mL min-1) of HEPES buffer solution and the mixture was passed through a 10 cm single bead string reactor containing acetylcholinesterase (I) immobilized on glass beads (0.5 to 0.75 mm). The H+ produced was detected by a pH electrode with a wall-jet entry to assay I activity. Insecticide sample solution was passed through the reactor for 15 min instead of the working buffer. The working buffer was then reintroduced into the carrier line and the substrate solution was injected again to determine I activity. The concentration. of insecticide was determined by the inhibition of enzyme activity. I was reactivated by passing 20 µM 2-pyridine aldoxime methiodide solution through the reactor for 15 to 20 min. The method was applied in the analysis of simulated seawater. Calibration graphs are presented for paraoxon and malathion. Detection limits ranged from 0.5 ppb for malathion to 275 ppb for bromophos-methyl. A flow injection system, incorporating an acetylcholinesterase (AChE) single bead string reactor (SBSR), for the determination of some organophosphorus (azinphos-Et, azinphos-Me, bromophos-Me, dichlorovos, fenitrothion, malathion, paraoxon, parathion-Et, and parathion-Me) and carbamate insecticides (carbofuran and carbaryl) is presented. The detector is a simple pH electrode with a wall-jet entry. Variations in enzyme activity due to inhibition are measured from pH changes when the substrate (acetylcholine) is injected before and after the passage of the solution containing the insecticide. The percentage inhibition of enzyme activity is correlated to the insecticide concentration. Several parameters influencing the performance of the system are studied and discussed. The detection limits of the insecticides ranged from 0.5 to 275 ppb. The determination of these compounds was conducted in Hepes buffer and a synthetic seawater preparation The enzyme reactor can be regenerated after inhibition with a dilute solution of 2-PAM and be reused for analysis. The immobilized enzyme did not lose any activity up to 12 weeks when stored at 4°C.
Insecticides Paraoxon Malathion azinphos-methyl Azinphos ethyl Bromophos Dichlorophos Fenitrothion Ethylparathion Methylparathion Carbofuran Carbaryl Electrode Immobilized enzyme Glass beads Single bead string reactor Buffer

"Potentiometric Flow Injection Detection Of Copper(II) With A Graphite Carbon Electrode"
Anal. Lett. 1998 Volume 31, Issue 1 Pages 13-25
ZuLiang Chen; Peter W. Alexander

Abstract: A graphite C electrode was evaluated in a potentiometric flow injection system for the detection of Cu2+. The electrode response characteristics were studied by both cyclic voltammetry and potentiometry, and probably the electrode potential change results in the adsorption of Cu2+ at the electrode surface. The C electrode was used for the flow injection potentiometric detection of Cu2+ in 0.05 mol/L NaOAc-0.2 mol/L NaCl at pH of 6.0 carrier solution A linear response in concentration. range of 1 x 10^-5-1 x 10^-2 mol/L was obtained with a detection limit of 5 x 10^-5 mol/L. The electrode described in this paper is simple and low cost.
Copper(II) Electrode Potentiometry Apparatus Detector

"Chemiluminescence Flow Injection System For Rapid Detection Of Red Tide Phytoplankton, Chattonella Antiqua"
Anal. Lett. 1998 Volume 31, Issue 13 Pages 2279-2288
Ryoichi Asai; Ritsuko Matsukawa; Kazunori Ikebukuro; Isao Karube

Abstract: A chemiluminescent flow injection analysis (FIA) system to detect the red tide phytoplankton, Chattonella antiqua, was developed based on a Cypridina luciferin analog, 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-α]-pyrazin-3-one (MCLA), which strongly emits light at 465 nm in the presence of superoxide. The system consists of a 2-reagent feeding stream, a sample injector, a joint for mixing MCLA and sample, a chemiluminescence (CL) reaction cell, a CL detector, and a recorder unit. Response time is ~1 min/measurement cycle. The FIA system has an optimum pH of 10.7. Calibration curves for C. antiqua displayed linearity from 2 x 103 to 2 x 104 cells/mL. When used to measure C. antiqua, sensitivity of the FIA system was ~10 times higher than that of the cytochrome c method. The FIA system is a rapid, practical method to detect C. antiqua.
Phytoplankton, chattonella antiqua, red tide Chemiluminescence Optimization pH Method comparison

"Continuous-flow And Flow Injection Stripping-voltammetric Determination Of Silver(I), Mercury(II) And Bismuth(III) At A Bulk Modified Graphite-tube Electrode"
Electroanalysis 1997 Volume 9, Issue 6 Pages 481-489
Ruidong Ye, Soo Beng Khoo*

Abstract: In continuous-flow analysis (CFA) sample solution [in 0.1 M acetate medium of pH 4.32, 0.1 M phosphate buffer of pH 5.5, and Britton-Robinson buffer of pH 3.8 for Ag(I), Hg(II), and Bi(III), respectively] was pumped through the flow cell for 10 min at 1.41 ml/min and accumulation was carried out under open circuit conditions. Then deaerated stripping solution [70 mM HCl, 75 mM KBr, 100 mM HNO3, and 1 M HCl for Ag(I), Hg(II), and Bi(III), respectively] was passed through the cell at 0.72 ml/min and after 15 s the appropriate deposition potential was applied [-0.15, -0.20, and -0.50 V (vs. Ag/AgCl) for Ag, Hg and Bi, respectively] for 15 s. Finally, differential-pulse anodic-stripping was carried out commencing at the deposition potential of the metal. For FIA (details given), the analysis was very similar and calibration graphs (CG) were linear for 5 nM- to 1 µM-Ag(I), 10 nM- to 2 µM-Hg(II) and 100 nM- to 5 µM-Bi(III). The respective detection limits (DL) were 0.18, 1.9 and 9.5 nM; RSD (n = 6) were 2.53-10.5, 2.57-5.77 and 5.97-7.9%, respectively. For FIA, CG were linear from 50 nM- to 5 µM-Ag(I), 100 nM- to 5 µM-Hg(II), and 5-50 µM-Bi(III), and the respective DL were 11, 20 and 1200 nM. RSD (n = 6) were 6.32, 6.44 and 7.9%, respectively.
Silver(I) Mercury(II) Bismuth(3+) Voltammetry Electrode Electrode

"High Performance Ion-chromatographic Separation Of Uranium And Thorium In Natural Waters And Geological Materials"
J. Chromatogr. A 1992 Volume 602, Issue 1-2 Pages 119-125
Michael P. Harrold*, Archava Siriraks and John Riviello

Abstract: Digested rock samples and water were analyzed on a column (25 cm x 4 mm) of Ion Pac CS-2 with a linear gradient of 0.6 M HCl to 0.6 M HCl - 0.5 M Na2SO4 at 1.0 mL min-1. Detection was by post-column derivatization with 0.3 mM arsenzo III in 0.5 M acetic acid containing 0.1% Triton X-100 at 0.5 mL min-1 and measurement at 660 nm. With samples containing 50 µg L-1 or with a high ionic strength, pre-concentration. was carried out on a column of MetPac CC-1 at pH 5.5, followed by elution with 20 M ammonium acetate. The results on reference rock and seawater standards were close to certified values.
Uranium Thorium-232 HPIC Sample preparation Spectrophotometry Post-column derivatization Reference material Metpac Triton X Surfactant

"Determination Of Cadmium And Lead At .mu.g/l Levels In Aqueous Matrices By Chelation Ion Chromatography"
J. Chromatogr. A 1993 Volume 640, Issue 1-2 Pages 207-216
N. Cardellicchio, S. Cavalli, J. M. Riviello

Abstract: Filtered seawater was preserved with concentrated HCl and before analysis was adjusted to pH 5.5 with 2 M ammonium acetate and Cd and Pb were pre-concentrated on a MetPac-CCl column (5 cm x 4 mm) packed with styrene-based macroporous cross-linked iminodiacetate-treated chelating resin (20 µm particles). The Cd and Pb were eluted with 75 mM H2SO4/0.1 M HCl/0.1 M KCl and separated by ion chromatography on an IonPac CS10 column (25 cm x 4 mm) packed with solvent-compatible poly(styrene-divinylbenzene) (8.5 µm particles) agglomerated with ion-exchange latex. The eluent (1 ml/min) was that used for pre-concentration. Post-column derivatization was carried out with 0.3 mM 4-(2-pyridylazo)resorcinol in 1 M 2-dimethylaminoethanol/aqueous 0.5 M NH3/0.5 M NaHCO3 buffer solution and detection was at 520 nm. Calibration graphs were rectilinear up to 500 ng of Cd and Pb. Detection limits were 2 and 6 ng of Cd and Pb, respectively.
Cadmium Lead HPIC Chelation Post-column derivatization Iminodiacetate Latex Metpac

"Determination Of Copper, Nickel, Zinc, Cobalt And Manganese In Seawater By Chelation Ion Chromatography"
J. Chromatogr. A 1993 Volume 640, Issue 1-2 Pages 365-369
Raffaela Caprioli and Sandro Torcini

Abstract: Seawater (100 ml) was mixed with 10^-20 mL of 2 M ammonium acetate of pH 5.4 and pre-concentration of the cited metals was carried out by passing the sample through a MetPac CC-1 column and a TMC-1 column. The metals were eluted from the TMC-1 column with 0.35 M HNO3, after washing with with 0.1 M ammonium nitrate (pH 3.5). Analysis was on a CS5 separation column of mixed ion-exchange resin, equipped with a similar pre-column, with pyridine-2,6-dicarboxylic acid as eluent (1 ml/min) and spectrophotometric detection after post-column derivatization with 4-(2-pyridylazo)resorcinol. Calibration graphs were rectilinear from 0.1 ng (detection limit) to 250 ng of the cited metals; RSD were 0.3-16.2%.
Copper Nickel Zinc Cobalt Manganese HPIC Spectrophotometry Chelation Preconcentration Metpac Post-column derivatization

"Determination Of Trace Metals In Seawater By Graphite-furnace Atomic Absorption Following Online Separation And Preconcentration"
Spectrochim. Acta B 1993 Volume 48, Issue 1 Pages 91-98
Laerte C. Azeredo, Ralph E. Sturgeon and Adilson J. Curtius

Abstract: The elements Cd, Cu, Fe, Mn, Ni, Pb and Zn were pre-concentrated as their chelates in a flow injection manifold (diagrams given) on a column of silica-immobilized quinolin-8-ol (20 µL) and eluted with 2 M HCl - 0.8 M HNO3 followed by AAS. The recoveries from reference materials were between 92 and 100% with coefficient of variation (n = 4 to 7) from 2 to 12%. The results were close to certified values. Detection limits were from 0.36 to 2.04 ng L-1 for a 5 mL sample.
Cadmium Copper Iron Manganese Nickel Lead Zinc Spectrophotometry Preconcentration Chelation Reference material Silica 8-Hydroxyquinoline

"Investigation Of Online Coupling Electrothermal Atomic Absorption Spectrometry With Flow Injection Sorption Preconcentration Using A Knotted Reactor For Totally Automatic Determination Of Lead In Water Samples"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1891-1908
Michael Sperling*, Xiu-ping Yan and Bernhard Welz

Abstract: Diagrams and a table of the valve sequence of the manifold are presented;incorporates a knotted reactor of PTFE tubing (1 m x 0.5 mm i.d.) on which the Pb(II)-diethyliocarbamate complex (cf. Welz et al., Appl. Sp ectrosc., 1991, 45, 1433) was collected and from which, after drying with a stream of air, the complex was eluted with 50 µL of ethanol and propelled by air to an AS-70 furnace autosampler for Zeeman AAS with use of a transversely heated graphite atomizer (heating program tabulated). The enhancement factor for 0.01-0.05 µg/l of Pb collected at a loading rate of 6.8 ml/min for 1 min was 142 (detection limit 2 ng/l), and for 0.1-2 µg/l at 3 ml/min for 30 s was 21. The RSD (n = 7) at 0.01 and 0.5 µg/l of Pb were 4.9 and 2.9%, respectively. Application to seawater necessitated use of the method of standard additions. Results for standard reference water samples agreed well with the certified values.
Lead Spectrophotometry Knotted reactor Reference material Standard additions calibration Preconcentration

"A Comparison Of Preconcentration Reagents For Flow Injection Analysis Flame Atomic Spectrometry"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1909-1915
G. M. Greenway*, S. M. Nelms, I. Skhosana and S. J. L. Dolman

Abstract: The chelating resins Chelamine and Chelosolve (Fluka), the immobilized-iminodiacetate controlled-pore glass PROSEP Chelating-1 (Bioprocessing Ltd., Consett, UK) and an in-house-prepared immobilized-quinolin-8-ol controlled-pore glass (CPG-8-HQ) were evaluated for rapid online pre-concentration and matrix separation in the flow injection AAS determination of Cd, Cu(II), Mn(II), Ni(II) and Zn in a flow injection manifold designed for rapid matrix separation. With all four materials the matrix-matching of standards for determining the cited heavy metals in seawater was unnecessary. The most suitable material was PROSEP Chelating-1, which, however, showed inferior selectivity to CPG-8-HQ.
Cadmium Spectrophotometry Preconcentration 8-Hydroxyquinoline Controlled pore glass Iminodiacetate

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

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

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

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

"First-order Speciation Of Arsenic Using Flow Injection Hydride-generation Atomic Absorption Spectrometry With In Situ Trapping Of The Arsine In A Graphite Furnace"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1781-1790
Scott N. Willie

Abstract: Use of the manifold described permits rough 'first-order' speciation in terms of a distinction between combined results for As(III), As(V), methylarsonic acid and dimethylarsinic acid and for these species plus, e.g., arsenobetaine, arsenocholine and tetramethylarsonium, which are unreactive towards NaBH4 and are consequently oxidized by online UV photolysis or off-line microwave heating in the presence of NaOH and K2S2O8 and determined as a group by difference. The method has been applied to biological tissues and aquatic plants (sample preparation described). A non-hydride-forming As fraction has been detected in NIST SRM 2670N urine, and the results for a series of seawater standards have led to the recommendation that the values for As be described as 'hydride-reactive' As.
Arsenic(3+) Arsenic(5+) Arsenoβine Arsenocholine Dimethylarsinic acid monomethylarsonic acid tetramethylarsonium ion Sample preparation Spectrophotometry Speciation Volatile generation Volatile generation Photochemistry UV reactor

"Determination Of Lead In Seawater With A Graphite Furnace Atomic Absorption Spectrometer And An Improved Automatic Online Preconcentration System"
Spectrochim. Acta B 1995 Volume 50, Issue 2 Pages 197-203
Zhen-Shan Liu and Shang-Da Huang*

Abstract: An improved automatic on-line pre-concentration system for graphite furnace atomic absorption spectrometry (GFAAS) for the determination of trace metals in sea-water was developed. This system was modified from a Perkin-Elmer AS-40 autosampler by mounting a silica gel C18 microcolumn near the tip of the autosampler capillary. The pre-concentration procedure was performed by using a four-way distribution valve and controlled by a programmable controller. The pre-concentration system developed previously was improved by using a peristaltic pump to replace the reciprocating pumps, a newly designed tube bed adjuster to release the back-pressure in the pre-concentration system, and a better control program, such that on-line pre-concentration became more reliable and fully automatic. The chelating agent ammonium pyrolidinedithiocarbamate (APDC) and a miniature column packed with 5 mg of C18 silica gel were used for pre-concentration. This system was tested by analyzing the lead content in reference standard sea-water samples. A sample volume of only 2 mL was required to determine lead in sea-water. The relative limit of detection of lead was 3.5 pg/ml.
Lead Spectrophotometry Preconcentration

"Evaluation Of Electrochemical Hydride Generation For The Determination Of Arsenic And Selenium In Seawater By Graphite-furnace Atomic Absorption With In-situ Concentration"
Spectrochim. Acta B 1996 Volume 51, Issue 11 Pages 1325-1334
W. -W. Ding and R. E. Sturgeon*

Abstract: A continuous-flow electrochemical hydride generation technique coupled with in situ concentration in a graphite furnace has been developed for determination of As and Se in seawater. Lead is used as cathode material for the production of arsine and hydrogen selenide. The efficiency of generation of arsine from As(III) is 86±6%, that from As(V) ranges from 73% to 86%. The efficiency of generation of hydrogen selenide from Se(IV) is 60±5% and from Se(VI) is 30±5%. The hydrides are trapped in an iridium-palladium coated graphite furnace prior to atomization. Absolute detection limits and concentration detection limits of 84 pg (3s(blank)) and 84 pg mL-1 for determination of As using 1 mL sample volume and 75 pg (3s(blank)) and 7.5 pg mL-1 for determination of Se using 10 mL sample volumes are obtained, respectively. The precision of replicate measurement for the analysis of reference materials at the 1.3 µg L-1 level for As(III) (0.8 ng absolute mass level) and at the 0.042 µg L-1 level for Se(IV) (0.42 ng absolute mass level) is better than 4% and 23% (relative standard deviation, RSD), respectively. The RSD values quoted above for Se include errors introduced by the sample preparation procedure.
Arsenic Selenium Spectrophotometry Reference material Electrochemical product conversion Preconcentration

"Determination Of Some Rare Earth Elements In Seawater By Inductively Coupled Plasma Mass Spectrometry Using Flow Injection Preconcentration"
Spectrochim. Acta B 1998 Volume 53, Issue 9 Pages 1281-1287
O. Vicente, a, A. Padr&oacute;a, L. Martineza,*, R. Olsinab and E. Marchevskyb

Abstract: An online Eu, Tb, Ho, Tm and Lu pre-concentration and determination system implemented with inductively coupled plasma mass spectrometry associated to a flow injection method was studied. Quinolin-8-ol and Amberlite XAD-7 were used for the retention of Eu, Tb, Ho, Tm and Lu, at pH 10.0. The rare earth elements were re-extd. from the microcolumn with nitric acid. The detection limits for the pre-concentration of 100 mL of aqueous solution of Eu, Tb, Ho, Tm and Lu were 0.016, 0.0023, 0.0017, 0.0035 and 0.0015 pg/mL, respectively, with a relative standard deviation of ~2.0%. The calibration graphs obtained using the pre-concentration system for Eu, Tb, Ho, Tm and Lu were linear at levels near the detection limits up to at least 1 ng/mL. The method was applied to the determination of Eu, Tb, Ho, Tm and Lu in seawater samples.
Metals, rare earth Europium Terbium Holmium Lutetium Mass spectrometry Preconcentration Amberlite 8-Hydroxyquinoline pH

"The Application Of Flow Injection Iminodiacetic Acid-ethylcellulose Membrane Preconcentration And Separation Technique To Atomic Spectrometry"
Spectrochim. Acta B 1998 Volume 53, Issue 10 Pages 1437-1445
Xiaoru Wang*, Zhixia Zuang, Chenlong Yang and Fan Zhyu

Abstract: A flow injection-based online iminodiacetic acid-ethylcellulose (IDAEC) membrane pre-concentration. and separation technique was developed, which has the advantages of easy operation without membrane plugging problems; a high enrichment factor (>10 for most elements); a high sample throughput (30 samples/h). The characteristics of the IDAEC membrane were systematically studied, including the effect of sample flow rate and analyte concentration. on break-through point; dynamic capacity and the lifetime of the IDAEC membrane. The technique was applied to pond water and seawater anal. in which all elements studied are in ng/mL level. The anal. performance was verified with recovery of a standard addition from seawater.
Spectrophotometry Membrane Preconcentration Standard additions calibration

"Determination Of Plutonium In Seawater Using Co-precipitation And Inductively Coupled Plasma Mass Spectrometry With Ultrasonic Nebulization"
Spectrochim. Acta B 1998 Volume 53, Issue 6-8 Pages 1221-1233
Ahmet E. Eroglua, Cameron W. McLeoda,*, Kinson S. Leonardb and David McCubbinb

Abstract: A flow injection-inductively coupled plasma-mass spectrometric (FI-ICP-MS) procedure, utilizing ultrasonic nebulization with membrane desolvation (USN/MD), was developed for the determination of Pu in seawater at fg/L concentration. levels. Seawater samples (11), after filtration, were subjected to co-precipitation with NdF3, followed by ion exchange to enrich Pu and to reject seawater matrix ions and co-existing U. The seawater concentration (1.0 mL) was then analyzed by FI-ICP-MS. The limit of detection for 239Pu in seawater based on an enrichment factor of 1000 was 5 fg/L, and precision at the 0.80 pg/L level was 12% RSD. Accuracy was verified via recovery experiments, and by comparing survey data for the Irish Sea with that derived by standard methodology based on co-precipitation and α-spectrometry. Concentrations for dissolved 239Pu and 240Pu in the Irish Sea were 0.267-0.941 pg/L (0.614-2.164 mBq/L) and 0.051-0.196 pg/L (0.428-1.646 mBq/L), respectively.
Plutonium-239 Plutonium-240 Ion exchange Mass spectrometry Nebulizer Coprecipitation Method comparison

"Critical Evaluation Of A Multi-element Electrothermal AAS System Using Line Sources And A Transversely Heated Graphite Atomizer With Zeeman-effect Background Correction"
Spectrochim. Acta B 1993 Volume 48, Issue 11 Pages 1381-1392
M. Berglund, W. Frech and D. C. Baxter, B. Radziuk

Abstract: The cited system, which consisted of a spatially isothermal transversely heated graphite atomizer (THGA) with integrated platform and Zeeman-effect background correction and mounted in an echelle polychromator, was constructed (diagram given) and evaluated for use in simultaneous multi-element analysis by AAS. By using beam splitters, as many as four line sources could be combined. Under multi-element conditions, characteristic mass values were similar to those obtained with conventional line-source electrothermal AAS with a THGA, although detection limits were about an order of magnitude poorer. This loss of detection was due to low radiation flux through the polychromator and light losses in the optical system. Design modifications are suggested to overcome these problems. A more general disadvantage with line-source AAS is the short working range. The instrument was used to determine Cd, Cu and Pb simultaneously in seawater samples following pre-concentration and matrix separation in a flow injection system (discussed).
Cadmium Copper Lead Spectrophotometry Preconcentration Matrix removal

"Flow Injection Spectrophotometric Determination Of Trace Amounts Of Bromide By Its Catalytic Effect On The Hydrogen Peroxide Oxidation Of Pyrocatechol Violet"
Anal. Sci. 1988 Volume 4, Issue 3 Pages 273-276
N. YONEHARA, S. AKAIKE, H. SAKAMOTO and M. KAMADA

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

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

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

"Preconcentration, Separation And Multi-elements Determination In Seawater Using A Cellulose-zinc Hydroxide System With Inductively Coupled Plasma Atomic Emission Spectrometry"
Anal. Sci. 1992 Volume 8, Issue 1 Pages 45-50
I. M. M. KENAWY

Abstract: The use of a cellulose-Zn(OH)2 mixture for the determination of traces of Cd(II), Cr(III), Cu(II), Fe(III), Hg(II), La(III), Ni(II), Pd(II), Sn(IV), and vanadate ion in seawater at different pH's was carried out employing the ICP technique. The effects of the concentration. of Zn(II), mass of the cellulose, shaking time, and pH on the pre-concentration were studied. The method is simple and applicable to the trace determination of 10 heavy metals at the ppb level. The effect of alkali and alkaline earth cations on the pre-concentration of the tested metal ions was examined The distribution coefficient Kd is in the range 102.86-106.31 mL/g.
Cadmium(2+) Chromium(III) Copper(3+) Iron(III) Mercury(II) Lanthanum(3+) Nickel(II) Palladium(II) Tin(IV) Spectrophotometry Multielement PPB Preconcentration pH Optimization

"Flow Injection Determination Of The Total Water Hardness By Using A Copper(II)-ion-selective Electrode And A Copper(II) Ion Buffer"
Anal. Sci. 1992 Volume 8, Issue 5 Pages 631-635
T. IMATO, K. ISHII and N. ISHIBASHI

Abstract: The flow injection system comprised two double-plunger pumps, a sample injector and a flow-through-type Cu2+-selective electrode detector (FLC 12, Denki KK). The output signals from a potentiometer were recorded. Sample solution (200 µL) containing Ca2+ and/or Mg2+ was injected into a stream of water that then merged with a stream of 0.5 M NaNO3. This mixed stream then mixed with the Cu2+ buffer [2.5 mM Cu(NO3) - 5 mM EDTA - 0.1 mM triethylenetetramine (I) - 0.5 M KNO3, adjusted to pH 9.4 with aqueous 0.1 M NH3 and 0.1 M NH4NO3] and passed to the flow-through electrode detector. Chloride interference was eliminated by the addition of I. The total hardness of seawater samples was determined at a rate of 30 h-1 with a coefficient of variation of 0.7%. A potentiometric determination of the total water hardness by flow -injection anal. is proposed, which uses both a Cu2+-selective electrode and a Cu2+ buffer stream comprising a Cu-EDTA complex and free EDTA. This method is based on the potentiometric change in the free Cu2+ concentration. in the buffer with a Cu2+-selective electrode, caused by the reaction of Ca2+ and Mg2+ with free EDTA in the buffer. Cl- interference was eliminated by adding triethylenetetramine to the Cu2+ buffer. The total hardness of seawater could be determined at a sampling rate of 30 h-1 and relative standard deviation 0.7%. The results were in good agreement with those obtained by conventional chelatometric titration.
Hardness Electrode Potentiometry Method comparison Interferences Buffer

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

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

"Online Pretreatment With Cobalt(III) Ions For A Flow Injection Spectrophotometric Determination Of Organic Phosphorus"
Anal. Sci. 1995 Volume 11, Issue 5 Pages 787-792
H. TANAKA, T. FUKUOKA and K. OKAMOTO

Abstract: Portions (500 µL) of solutions of standard organophosphorus compounds (1 mg/l as P; tabulated) were injected into a carrier stream of water and mixed with a stream of water containing 32 mM Co(III) in a coil (5 m x 1 mm i.d.) containing a Pt wire (3 m x 0.2 mm i.d.). The mixed solution was treated with ammonium molybdate/ascorbic acid reagent injected into the flow system and mixed in a coil (1 m x 1 mm i.d.) at 75°C and the absorbance of the colored product formed was measured at 880 nm. The calibration graph was linear up to 1.5 mg/l of P and the detection limit was 0.005 mg/l. RSD (n = 10) was 3% for 1 mg/l (as P) disodium phenyl phosphate. Average recoveries were ~100% for all the model compounds studied. The method was applied to the determination of P in water samples. Results were in good agreement with those obtained by Official methods except for water samples with high-chloride content (i.e. seawater). Sample throughput of 10^-12/h was achieved by this method.
Phosphorus Spectrophotometry Heated reaction Standard method Method comparison

"Flow Injection Titration Of Alkalinity In Natural Waters"
Anal. Proc. 1987 Volume 24, Issue 12 Pages 360-362
David R. Turner, Susan Knox, Michael Whitfield, Margarida Correia dos Santos

Abstract: A flow injection manifold for alkalinity measurements is described and illustrated; it consists of a mixing chamber, a capillary glass electrode detector and a reference electrode contacting the main flow stream via a free-diffusion liquid junction. A solution of 50 µM-HCl in 0.1 M NaCl is injected into a seawater carrier solution and potential readings are taken at a frequency of 5 Hz. The precision of the method is generally <1% and 30 samples h-1 can be analyzed.
Alkalinity Electrode Electrode Mixing chamber Review Titrations

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

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

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

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

"Analysis Of Trace Metals In Seawater By Inductively Coupled Plasma Mass Spectrometry And Related Techniques"
Anal. Proc. 1993 Volume 30, Issue 3 Pages 159-161
Martin J. Bloxham, Steve J. Hill, Paul J. Worsfold

Abstract: Methods of matrix interference suppression or removal in such analyzes are reviewed, with particular reference to coupled online pre-concentration. and matrix removal methods based on flow injection or LC. The application of such techniques in conjunction with AAS, ICP-AES and ICP-MS detection is also discussed, as are such approaches to matrix suppression as multivariate calibration. (33 references).
Metals, trace Mass spectrometry Review Interferences Multivariate calibration

"Matrix Suppression In Seawater Analysis Using Inductively Coupled Plasma Mass Spectrometry With Mixed Gas Plasmas"
Anal. Proc. 1994 Volume 31, Issue 3 Pages 95-97
Martin J. Bloxham, Paul J. Worsfold and Steve J. Hill

Abstract: Seawater was analyzed by ICP-MS using a standard ICP-MS instrument (VG PQ2, VG Elemental, Winsford, Cheshire, UK) operated in quantitative scan mode. Nitrogen was added to the nebulizer gas with use of a mass-flow controller or a gas blender, to eliminate polyatomic interferences and improve metal detection limits. The operating conditions (details given) were optimized by means of a simplex procedure to eliminate interference due to ArNa+. The optimum conditions generally agreed well with those reported previously by Gray and Williams (J. Anal. Atomic Spectrom., 1987, 2, 599). Detection limits for 63Cu+ improved from 12.9 to 0.06 µg/l and interferences were reduced at other masses viz. 58Ni+, 64Zn+, 65Cu+, Co+ and Mo+ using the same conditions. Precision was also enhanced; RSD (n =5) for 0-10 µg/l were 2.6% compared with 16.3% for the standard method. Linearity was also improved in this range. Measurements made with reference seawater; real seawater would require a pre-concentration method possibly involving an FIA procedure.
Metals Mass spectrometry Interferences Preconcentration Simplex Standard method Method comparison

"Flow Injection Determination Of Nitrate In Estuarine And Coastal Waters"
Anal. Proc. 1994 Volume 31, Issue 3 Pages 81-83
Trevor McCormack, Anthony R. J. David, Paul J. Worsfold and Robin Howland

Abstract: Water (260 µL) was injected into a NaCl stream (0.23 ml/min), merged with an NH4Cl carrier stream (0.23 ml/min) and mixed thoroughly in a column (2 cm x 3 mm i.d.) packed with glass beads (1.5-2 mm o.d.). After mixing, the stream passed through a Cd reactor column and was merged with the color reagent stream (0.16 ml/min) composed of N-(1-naphthyl)ethylenediamine dihydrochloride/sulfanilamide in a reaction coil (200 cm). The resulting pink-purple color was detected spectrophotometrically at 540 nm. The FIA manifold is shown schematically. The calibration graph was linear from 0.1 (detection limit) to 73 µM-nitrate. For higher nitrate concentrations, as occur in terrestrial discharges, the range can be extended up to 730 µM-nitrate by the use of a 50 µL sample loop. The RSD (n = 6) were 1.6 and 2% for 73 and 1 µM-nitrate, respectively.
Nitrate Spectrophotometry Glass beads

"Flow Injection Analysis For Seawater Micronutrients"
Adv. Chem. Ser. 1985 Volume 209, Issue 1 Pages 7-30
Kenneth S. Johnson, Robert L. Petty, and Jens Thomsen

Abstract: Flow-injection analysis (FIA) is a technique for automating chemical analyzes. The principles of FIA are reviewed here. Methods for applying FIA to the anayses of nitrate, nitrite, phosphate, silicate, and total amino acids in seawater are examined. Analyses of other nutrients, metals, and carbonate system components are also discussed. Various techniques to eliminate the refractive index effect are reviewed. Finally, several examples of the application of FIA to oceanographic problems are presented.
Nitrate Nitrite Phosphate Silicate Amino Acids

"Continuous-flow Device For Oxygen Extraction From Natural Waters And Conversion To Carbon Dioxide For Isotopic Analysis"
An. Acad. Bras. Cienc. 1981 Volume 53, Issue 1 Pages 57-60
Braathen, C., Rebello, A.L.

Abstract: Unopened sample bottles containing natural waters are subjected to a 2.3-L/h flow of purified N2 which flushes the dissolved O2 out of the water samples, into 2 water retention traps, and then, through a 400°C oven for quantitative conversion to CO2 over activated C and a Ni catalyst. The CO2 flows with the N2 carrier out of the oven and is collected in a liquid N trap. This extraction-conversion is efficient (systematically extracting ~4.5% more dissolved O2 from seawater than the Winkler Method) and yields a CO2 product for which the O isotope determinations are reproducible (0.16% standard deviation) and accurate. (SFS)
Oxygen Mass spectrometry Sample preparation Apparatus Extraction

"Online FIA Atomic Spectrometry For The Analysis Of Metal Traces"
Ann. Chim. 1995 Volume 85, Issue 7-8 Pages 443-454
MENTASTI E

Abstract: A review is presented, with 28 references. It is concluded that the practical blank-limited detection limit obtainable by flow injection pre-concentration online with atomic spectrometry has nearly been reached, and that the only further possibility (apart from the impractical use of a larger sample volume) is the development of flow injection ICP-MS. Sensitivity of the pre-concentration to the chemical state of the metal indicates the possibility of using flow injection atomic spectrometry for speciation. Online flow injection analysis (online FIA) for the determination of metal traces by atomic spectrometry is reviewed and discussed with reference to environmental applications. The FIA manifold comprises a microcolumn packed with XAD-2 resin which retains the analytes in form of metal complexes. Successive elution enables the achievement of an enrichment step with which very low detection limits can be reached. (28 references)
Cadmium Copper Iron Manganese Nickel Zinc Mass spectrometry Sample preparation 8-Hydroxyquinoline Chelex Preconcentration Review Solid phase extraction Speciation

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

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

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

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

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

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

"Continuous-flow Method For The Determination Of Phosphorus Using The Fluorescence Quenching Of Rhodamine 6G With Molybdophosphate"
Bunseki Kagaku 1984 Volume 33, Issue 2 Pages 116-119
Motomizu, S.;Mikasa, H.;Oshima, M.;Toei, K.

Abstract: The method was based on the reaction in acid medium between PO43- and molybdate to form molybdophosphate, which in turn reduces the fluorescence of Rhodamine 6G (C. I. Basic Red 1; I). The carrier solution (distilled water) and reagent solution (0.035 M Mo(VI) and 10 µM-I in 0.8 M HCl) were propelled (at 0.98 mL min-1) by a double-plunger pump, and sample solution (160 µL) was injected into the carrier solution The two streams were mixed in a PTFE tube (20 cm long), and the mixture was passed through an 18 µL flow-cell, where the fluorescence of I was measured at 580 nm (excitation at 350 nm). The calibration graph was rectilinear for 0 to 45 ppb of P. In the analysis of two seawater samples by this method, results of 24.4 and 36.5 ppb of P were obtained, as compared with 23.8 and 35.2 ppb, respectively, by the malachite green method (cf. Anal. Abstr., 1983, 45, 3H60). Co-existing foreign species did not interfere. A schematic diagram of the flow system, which could deal with 20 samples per hour, is presented.
Phosphorus Fluorescence Interferences Method comparison Quenching

"Continuous Determination Of Nitrite By Using A Second-derivative Spectrophotometer For The Gas Phase"
Bunseki Kagaku 1985 Volume 34, Issue 2 Pages 91-94
Nagashima, K.;Matsumoto, M.;Suzuki, S.

Abstract: The sample solution (at 50°C and 4 mL min-1) is mixed with 13 M H3PO4 - 0.13 M NaI (at 1 mL min-1) to reduce NO2- to NO. The reaction mixture is passed through a gas - liquid separator at 90°C comprising an inner tube of microporous PTFE (50 cm x 2 mm o.d., 1 mm i.d.) and an outer tube of glass (50 cm x 4 mm i.d.). The evolved NO is carried by a flow of N (150 mL min-1, 90°C) into the heated optical cell (150°C, path length 25 cm, volume 80 ml) of a spectrophotometer, and the second-derivative absorbance at 214.0 nm is continuously recorded. Equilibrium response is reached within 5 min. The formation of NO is quantitative for 0.5 µM to 1 mM NO2-. Water vapor has no effect on the absorbance, and therefore a scrubber is not required. The coefficient of variation was 2.1% for 10 µM-NO2- (n = 6). The method was applied to synthetic seawater.
Nitrite Spectrophotometry Heated reaction Teflon membrane

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

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

"Rapid Determination Of Zinc In Seawater By Column Preconcentration/AAS"
Bunseki Kagaku 1987 Volume 36, Issue 3 Pages 213-216
Hirata, S.;Honda, K.

Abstract: Sea-water (1 L) adjusted to pH 2.2 with 1 mL of concentrated HNO3) was mixed (6.0 mL min-1) with a stream of ammonium acetate buffer (pH 7; 0.5 mL min-1) and passed through a column (16 mm x 3.2 mm) of Chelex-100. The column was washed with water and the chelated Zn was eluted with similar, equals160 l of 2 M HNO3 (3.0 mL min-1) and determined by AAS. The limit of detection was 0.5 ppb of Zn, and the coefficient of variation was 2.7% for 10 ppb of Zn. The sampling rate was ~30 h-1.
Zinc Spectrophotometry Column Preconcentration

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

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

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

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

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

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

"Potentiometric FIA Of Chromium(VI) In Seawater"
Bunseki Kagaku 1994 Volume 43, Issue 1 Pages 31-37
Ohura, H.;Imato, T.;Yamasaki, S.;Ishibashi, N.

Abstract: Sample (200 µL) was injected into a stream of water (1 ml/min) which was merged with a reagent stream (1 ml/min) of 0.1 mM Fe(III)/0.1 mM Fe(II) containing 0.4 M NaBr and 1.2 M H2SO4. The resulting stream was passed through a reaction coil (100 cm x 0.5 mm i.d.) before detection of a sharp transient potential change using a redox potential electrode. The method was used for the determination of Cr(VI) in seawater. In the determination of 1 µM-Cr(VI) the RSD was 0.6% with a sampling rate of ~40/h; good recoveries were obtained. Cr(III), Cu(II), Zn(II), Ni(II) and Cd(II) did not interfere, even at a thousand-fold excess. Results are discussed.
Chromium(VI) Potentiometry Interferences

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

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

"Flow Injection Online Cobalt-APDC Coprecipitation Preconcentration And Determination Of Lead And Copper In Seawater With Graphite Furnace Atomic Absorption Spectrometry"
Can. J. Anal. Sci. Spectrosc. 1994 Volume 39, Issue 4 Pages 101-107
Zhuang, Z.X.;Wang, X.R.;Yang, P.Y.;Yang, C.L.;Huang, B.

Abstract: Sea water was filtered, adjusted to pH 3 and injected into an FIA manifold (schematic given). The sample (5 ml/min) was mixed with 2% 1-pyrrolidinecarbodithioic acid (APDC) solution (7 ml/min). Coprecipitation occurred, the precipitate was collected on the filter membrane and the filtrate was drawn off. A second loop (50 l) was filled with IBMK and the coprecipitation was stopped, residual filtrate was removed and the remaining precipitate was dried. a 50 l IBMK solution was pushed by an air stream into the filtering cup and dissolved the precipitate on the filter. The air then stirred the mixture of precipitate and IBMK solution and 40 l of the resulting solution was analyzed by GFAAS with use of a Perkin-Elmer Model 3030B instrument. The measurement wavelengths used were 283.4 and 324.8 nm for Pb and Cu, respectively. The detection limits were 0.05 and 0.001 g/l for Pb and Cu, respectively. The corresponding RSD were 4.8 and 3.2%. Recoveries were 94%.
Lead Copper Spectrophotometry Coprecipitation Preconcentration

"Preconcentration Of Trace Zinc In Seawater On CPPI Resin By FIA And Online Detection By ICP-AFS"
Chin. Chem. Lett. 1990 Volume 1, Issue 3 Pages 237-238
Dong Xing YUAN Peng Yuan YANG Xiao Ru WANG Ben Li HUANG

Abstract: A quite new type of chelating resin Carboxymethylated Polyethylenimine-Polymethylenepolyphenylene Isocyanate(CPPI) is used for the pre-concentration of Zn from high salt water such as seawater. The pre-concentration is controlled through the technique of Flow Injection Analysis (FIA). The concentrated sample solution is then directly transferred to an Inductively Coupled Plasma-Atomic Fluorescence Spectrometer (ICP-AFS) for determination. The detection limit of Zn by the technique is about 0.06 ppb.
Zinc Spectrophotometry Resin Preconcentration

"Flow Injection Analysis Of Seawater: Anionic And Organic Species"
Crit. Rev. Anal. Chem. 1991 Volume 22, Issue 5 Pages 331-344
J. Atienza; M. A. Herrero; A. Maquieira; R. Puchades

Abstract: Methodology for the analysis of compounds in seawater has developed rapidly during recent years, together with a markedly increased interest in chemical data to characterize the marine environment. Flow injection analysis (FIA) can play a significant role in laboratory automation for many traditional wet chemical methods, and can serve as the basis for new methods which have no conventional analog. The FIA technique permits the analysis of a great number of samples, rapidly and reliably. This review discusses the present status and potential applications of FIA in the determination of anions and organic species in seawater analysis.
Anions Organic compounds Review

"Flow Injection Analysis Of Seawater. 2. Cationic Species"
Crit. Rev. Anal. Chem. 1992 Volume 23, Issue 1-2 Pages 1-14
J. Atienza; M. A. Herrero; A. Maquieira; R. Puchades

Abstract: A review is presented, with 78 references. A summary of flow injection methods proposed for the determination of cationic species, viz., ammonia, alkaline-earth cations and trace elements, in seawater is given in tabular form and includes details of calibration ranges, detection limits, coefficient of variation and sampling frequencies (h-1). A review, with 78 references is given. Flow injection analysis (FIA) can provide a simple and versatile tool to determine metal cations in seawater. The use of FIA techniques coupled with online sample pre-concentration and matrix modification has recently attracted considerable research effort in attempts to control interference effects. The most common active agents used for sample pre-concentration are chelating resins of different types. The combination of FIA with detection techniques, such as atomic spectroscopy, for the determination of cationic species in the general context of seawater anal. is discussed.
Cations Review Interferences

"Trace Analysis Of Heavy Metals In Seawater. Flow Injection Analysis And Atomic Absorption Spectrophotometry"
Dan. Kemi 1983 Volume 64, Issue 3 Pages 68-70
Olsen, S.

Abstract: A flow injection anal.-at. absorption spectrometric method for the determination of heavy metals in fjord waters is described. The method is used to monitor the disposal of ore flotation tailings in a Greenland fjord. (SFS)
Metals, heavy Cadmium Lead Ion exchange Spectrophotometry

"Manganese And Iron In Hydrothermal Plumes Resulting From The 1996 Gorda Ridge Event"
Deep Sea Res. II 1998 Volume 45, Issue 12 Pages 2683-2712
Gary J. Massoth, Edward T. Baker, Richard A. Feely, John E. Lupton, Robert W. Collier, James F. Gendron, Kevin K. Roe, Stacy M. Maenner and Joseph A. Resing

Abstract: We sampled hydrothermal plumes over the N. Gorda Ridge four times between March and August 1996 to document Mn and Fe discharge resulting from a magmatic intrusion/seafloor eruption. Two separate event plumes, EP96A and B, and chronic hydrothermal emissions lasting similar to 6 months were characterized. Shipboard time-series measurements of an event plume sample were used to calibrate an Fe phase clock useful for estimating sample age up to similar to 6 days after fluid discharge. Samples collected from EP96A. and B had Mn/heat (< 0.15 nmol J-1) and Fe/Mn (> 2 mol mol-1) ratios similar to historical event plume observations. We suggest these 'signature' ratio values are generally characteristic of event plumes and hypothesize that Mn and Fe may be supplied to event plumes by different processes: Mn by entrainment of fluids from an extant shallow subseafloor reservoir, and Fe by short-lived, high-temperature water-rock reaction coincident with dike emplacement. Calculations based on the Fe phase clock indicate that the two event plumes were released more than a month apart. The largest event plume, EP96A (similar to 2.3 x 10(6) M Mn and 13 x 10(6) M Fe), formed similar to 7 March soon after seismic activity began. The smaller EP96B (similar to 0.49 x 10(6) M Mn and 3.5 x 10(6) M Fe) was not discharged until similar to 11 April, 3 weeks after the cessation of seismic activity detectable by SOSUS T-phase monitoring. We hypothesize that the subseafloor disturbance that triggered EP96B also resulted in the episodic flushing of a reservoir of chronic-plume-like fluids. Total event plume inventories of Mn and Fe at N. Gorda Ridge are much smaller than those associated with the 1986 event at N. Cleft segment of the Juan de Fuca Ridge, but comparable to event plume inventories at N. Cleft segment in 1987 and CoAxial segment in 1993, Mn/heat values for chronic plumes over the eruption site underlying EP96A evolved from moderate (similar to 0.25 oon-mol J-1, reflecting probable admixture with event plume formation fluids) to high (similar to 0.7 nmol J-1, typical of chronic plumes) to low (similar to 0.1 nmol J-(1,) similar to diffuse vent fluid values), marking a complete episode of intrusion/eruption-induced hydrothermal discharge.
Manganese Iron Spectrophotometry Remote instrument Process monitoring

"Rates And Mechanism Of Iron(II) Oxidation At Nanomolar Total Iron Concentrations"
Environ. Sci. Technol. 1995 Volume 29, Issue 3 Pages 818-824
D. Whitney King, Heather A. Lounsbury, and Frank J. Millero

Abstract: A fully automated luminol-based chemiluminescence system has been developed for rapid analysis of Fe(II) at natural levels. Using this system, the rates of Fe(II) oxidation in 0.7 M NaCl have been measured for nanomolar concentrations of Fe(II) over the pH range 7.0-8.3. When the production and decomposition of H2O2 in the system were considered, measured rates at these levels were in excellent agreement with a model based on previously reported rate constants determined using micromolar levels of Fe(II). These results show that O2- and OH. intermediates produced as a result of Fe(II) oxidation remain effective as Fe(II) oxidants in these controlled conditions. The chemical model for Fe(II) oxidation also allows prediction of steady-state H2O2 and O2- concentrations that result from the oxidation of micromolar levels of Fe(II). The concentration of both species increases exponentially with increasing pH. At pH 8.2, the predicted H2O2 and O2- concentrations are 220 and 2.3 nM, respectively. The predicted H2O2 concentrations are in excellent agreement with laboratory measurements. These results suggest that significant concentrations of H2O2 and O2- should be present at the oxic-anoxic interface of marine environments where micromolar levels of Fe(II) are in contact with dissolved oxygen.
Iron(2+) Chemiluminescence Kinetic Rate constants

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

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

"Merging Zone Flow Injection Analysis Of Trace Copper - Catalytic System Of Iron(III) - Thiosulfate - Copper(II)"
Fenxi Huaxue 1991 Volume 19, Issue 4 Pages 468-470
Yuan, Y.;Wang, P.;Wang, Y.

Abstract: A flow injection system (diagram given) is described for the determination of trace Cu, based on the reaction of Fe3+ and S2O32- in the presence of Cu2+ as catalyst. Optimum sensitivity was achieved at 36°C to 38°C, pH 2 to 3 and with use of 0.025 M Fe3+ and 0.15 M Na2S2O3. The absorbance of the reaction solution was measured at 540 nm. The calibration graph was rectilinear up to 0.35 µg mL-1 of Cu; the detection limit was 0.01 µg mL-1. The coefficient of variation (n = 7) was 1.7% for the determination of 0.1 µg mL-1 of Cu. The method was applied in the analysis of seawater with recoveries of 95 to 103%. Up to 500-fold of Pb(II), Mn(II), Co(II), Ni(II), Zn(II), Cd(II) and Fe(II) did not interfere. Analysis time was 100 samples h-1.
Copper Catalysis Heated reaction Interferences Merging zones pH

"Preconcentration Of Zinc In Seawater On Carboxymethylated Polyethylenimine Polymethylenepolyphenylene Isocyanate Resin By Flow Injection Analysis And Online Detection Using Inductively Coupled Plasma Atomic-fluorescence Spectrometry"
Fenxi Huaxue 1992 Volume 20, Issue 2 Pages 162-164
Yuan, D.;Wang, X.R.;Yang, P.Y.;Huang, B.

Abstract: Filtered seawater was injected into a column (1 x 0.3 cm) of carboxymethylated polyethylenimine polymethylenepolyphenyline isocyanate resin installed in a flow injection analyzer. for pre-concentration with 0.1 M ammonium acetate of pH 7 for 100 s, with elution with 1 M HNO3 (streams at 2 mL min-1). The concentrated eluate was transferred to an ICP atomic-fluorimetric spectrometer for analysis. The detection limit was 0.1 µg L-1 of Zn. No interference was observed.
Zinc Fluorescence Resin Preconcentration Interferences

"Study Of Online Chloride Removal By A Pre-column Connected With Low-pressure Ion Chromatography And Its Application"
Fenxi Huaxue 1995 Volume 23, Issue 1 Pages 86-88
Liang, L.L.;Wu, Q.F.;Guo, X.H.;Chen, Y.B.

Abstract: Sample (40 l) was loaded at 1 ml/min into a home-made online chloride removal precolumn (36 x 6 mm i.d.) of anion-exchange resin and 0.1 M AgNO3, as a flow system for clean up then through a separation column with 1.2 mM sodium carbonate/2.4 mM sodium hydrogen carbonate as eluent to separate fluoride, nitrite, nitrate and sulfate and a suppression column prior to detection with a conductivity detector operating at 500 and between -1 and 4 mV. Detection limits for fluoride, nitrite, nitrate and sulfate were 0.85, 0.62, 0.65 and 0.92 mg/l, respectively. The system was applied to the analysis of sea water and ground water.
Fluoride Nitrate Nitrite Sulfate HPIC Column

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

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

"Determination Of Trace Arsenic With L-cysteine As Prereductant Using Flow Injection-hydride Generation-atomic Absorption Spectrometry"
Fenxi Huaxue 1998 Volume 26, Issue 8 Pages 1037-1037
Xu, G.M.;Lu, X.H.;Yin, X.F.

Abstract: The title method is characterized by having low detection limit (0.05 µm/L), good precision (1.8% RSD), and fast operation (65 samples/h). The method has applied to the anal. of steel and sea water.
Arsenic Spectrophotometry Volatile generation

"Flow Injection Online Preconcentration With Active Carbon Fibre For Multi-element Determination In Water Samples Using ICP-AES"
Fenxi Kexue Xuebao 1995 Volume 11, Issue 2 Pages 16-20
Lin Yongjing; Gong Zhenbin; Zhuang Zhixia; Deng Zhiwei; Wang Xiaoru

Abstract: The FIA manifold systems for online column flows are shown schematically for pre-concentration and elution regimes. For the determination of Zn, Pb, Ni, Cd and Mn in mineral and seawater, an appropriate amount of the sample was mixed with 1 mL acetic acid/NH4 acetate buffer solution of pH 7 and 3 mL 0.05% quinolin-8-ol. Portions of the solution were injected at 3.1 ml/min on to columns (11-20 mm x 2.2-3.6 mm) of active carbon fiber and the analyte metals were eluted with 3 M HNO3 at 2.7 ml/min. Portions of eluate were injected into the ICP operating with an RF frequency of 27.15 MHz, an RF power of 1.2 kW, carrier gas of 1 l/min and observation height of 15 mm. The recoveries were 97.5-107.2% and the detection limits were 0.2-4 ng/ml.
Cadmium Lead Manganese Nickel Zinc Spectrophotometry Preconcentration 8-Hydroxyquinoline Column Carbon fiber

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

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

"Aluminum Binding To Humic Substances Determined By High Performance Cation-exchange Chromatography"
Geochim. Cosmochim. Acta 1997 Volume 61, Issue 1 Pages 1-9
Susan H. Sutheimer* and Stephen E. Cabaniss*

Abstract: Aluminum binding to humic substances is studied using high performance cation exchange chromatography (HP-CEC) in both laboratory and field samples. HP-CEC provides independent quantification of both free and complexed AI(III), eliminating many of the uncertainties associated with previous measurements of aluminum speciation. We formulate and calibrate a simple aluminum complexation model, using solutions with variable total Al(III) (0.2-11 µM) and pH (4.0-8.2) and constant organic composition (12.4 mg/l Suwannee River fulvic acid, FA). The model is verified with HP-CEC data from a group of acid lakes and from literature data. The results indicate that AI(III) complexation by natural organic matter in several environments is similar to complexation by FA, and that Al dimers are potentially important species even at low environmental concentrations of Al. Furthermore, organic complexation of Al is not limited to acidic waters but appears to be important even at the alkaline pH values typical of marine systems. Copyright (C) 1997 Elsevier Science Ltd 39 References
Aluminum, free Aluminum, bound HPIC Complexation Speciation

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

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

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

Manganese(II) Kinetic

"Behavior Of Rare Earth Elements In Seawater At The Ocean Margin: A Study Along The Slopes Of The Sagami And Nankai Troughs Near Japan"
Geochim. Cosmochim. Acta 1998 Volume 62, Issue 8 Pages 1307-1317
Jing Zhang and Yoshiyuki Nozaki

Abstract: Using a flow injection ICP-MS method, yttrium and all the lanthanides in seawater were determined in the coastal/offshore mixing regime near Japan. Marked enrichments in the trivalent rare earth elements (REEs) in the surface waters are ascribed to the influence of coastal waters from Tokyo Bay in Mar. and perhaps somewhere else in Sept. and Oct. to this region. At less than half of the stations where the detailed vertical profiles were obtained throughout the water column, we found marked excess REE(III) concentrations. near the bottom. These bottom concentration. anomalies are probably caused by resuspension of underlying sediments. Excluding these surface and bottom anomalous concentrations., the distribution of REE(III)s in the midwater column are very similar to those of the open ocean and are highly correlated with each other (R2 > 0.95). This suggests that the boundary effects on the chemical fractionation of REE(III)s are small. We find no effect of the boundary scavenging known for 210Pb and 231Pa on the REE distribution, whereas there may be preferential release of light and middle REE(III)s over heavy REEs from slope sediments to the seawater much like 227Ac. From the shale-normalized REE patterns, we obtained up to 90% negative Ce and 10%positive Gd anomalies in the water column.
Lanthanides Yttrium Mass spectrometry

"Online Cold-trap Hydride Collection Flow Injection Determination Of Arsenic And Antimony In Seawater"
Haiyang Xuebao 1989 Volume 9, Issue 2 Pages 255-261
Lu, Xiankun; Li, Jing; Chen, Shuzhu; Dai, Guosheng

Abstract: An automatic flow analysis system with on-line liquid nitrogen trap, hydride generation and flame-less atomic absorption spectrophotometry was presented for the determination of inorganic arsenic and antimony in seawater. The experimental conditions such as acidity of reduction reaction, the amount of sodium borohydride, the flow rate of carry gas (high purity of nitrogen) were tested and selected optimally. The limit detection of the method presented was 0.15 µg/L for arsenic and 0.24 µg/L for antimony. During the determination of seawater samples with levels microgram arsenic and antimony per liter the variation coefficient would be ±4% for arsenic and ±10% for antimony. The volume needed for one measurement was 9 mL for arsenic and 12 mL for antimony. The frequency of sample determination reached 20 times per hour for arsenic and 15 times per hour for antimony.
Arsenic Antimony Spectrophotometry Cold trap Volatile generation

"Automatic Determination Of Nutrients In Seawater. 3. Reverse Flow Injection Analysis Of Phosphate And Silicate"
Haiyang Xuebao 1991 Volume 13, Issue 1 Pages 60-67
Kang, Daiwen; Chen, Lu; Lu, Xiankun

Abstract: An automatic reverse flow injection analysis method for continuous determination of PO43- and SiO32- in water has a detection limit of 0.05 and 0.51 mmol/L, respectively, and relative standard deviations 1.86 and 2.6%, respectively. The analysis rate is 30 samples/h. The results by the method are in good agreement with the standard method.
Phosphate Silicate Spectrophotometry Automation Reverse Method comparison

"Development Of Apparatus That Monitors Seawater Pollution"
Hiroshima Kenritsu Seibu Kogyo Gijutsu Senta Kenkyu Hokoku 1998 Volume 41, Issue 1 Pages 53-56
Nobuo, S.;Hideo, W.;Kiyoshi, M.;Yoshiharu, K.;Megumi, K.;Yuichiro, T.;Yasujiro, M.;Kazunori, Y.;Norimi, T.

Abstract: As part of our efforts to develop an unmanned seawater environmental monitoring device for long-term observation of nitrogen and phosphates, which serve as indexes for eutrophication, the development was pursued of an automatic analyzer based on FIA (flow injection anal.). As the target of our anal. was seawater, we aimed at the development of equipment that can perform anal. at the standard level designated by regulations for seawater (in other words, total nitrogen of 0.2 mg/L or less and total phosphates of 0.02 mg/L or less). The newly developed device was capable of completing the process from sampling to anal. in 15 min. In field testing conducted in the area offshore of Kurahashi-jima Island, which is located in Aki-gun, Hiroshima Prefecture, we coupled the device to an automatic pretreatment app. we developed last year. The entire process, including the pumping, pretreatment, and anal. of the seawater, took a total of 30 min. The anal. results obtained with our device are in agreement with those from analyzes based on JIS methods, proving that the device can be satisfactorily utilized in actual anal.
Nitrogen Phosphate Method comparison Standard method Remote instrument Process monitoring Automation

"Flow Injection Methods For Monitoring The Environment"
Indian J. Environ. Prot. 1989 Volume 9, Issue 6 Pages 412-419
Mahadevappa, D. S.

Abstract: Flow injection analysis methods are presented for determination of S2- in solution, residual Cl in solution, and aromatic sulfonylhaloamines (e.g., chloramine-T and chloramine-B) and Fe(III) based on previously reported spectrophotometric methods. Optimum conditions for all the determinations are described. The detection limits were 0.14 to 1.4 ppm and max. sampling rates were >200 samples h-1. Beer's law ranges and tolerance limits for diverse ions are reported. At pH 4.0, Fe (23.4 ppm) was determined in the presence of 120 ppm of Fe by using the reaction with sulfosalicylic acid. Chlorine in seawater samples and iron in steel were determined by the described methods.
Chloramine T Chloramine, B Sulfide Chlorine Iron Spectrophotometry Detection limit Optimization Interferences

"Experience With Flow Injection Analysis In Limnological Research"
InFocus 1987 Volume 10, Issue 1 Pages 8-NA
Ripl, W.;Michel, J.

Abstract: NA
Nitrate Phosphorus Sulfate Spectrophotometry Tecator

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

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

"Spectrophotometric Determination Of Mercury(II) By Flow Injection Analysis"
Int. J. Environ. Anal. Chem. 1990 Volume 41, Issue 1-2 Pages 39-46
M. D. Mateo; R. Forteza; V. Cerd&aacute;

Abstract: A method is proposed that uses inhibition by Hg(II) of the catalysis by iodide of the As(III) - Ce(IV) reaction. Sample (125 µL) was injected into a stream (0.7 mL min-1) of 0.04 M Ce(IV) in 1.75 M H2SO4 which was then merged with a stream of 150 ng mL-1 of KI and 0.1 M As(III) same flow rate and acid concentration.) and fed through a reaction coil (6 m x 0.5 mm) at 55°C before detection of unused Ce(IV) at 460 nm. The rectilinear calibration range was 2 to 40 ng Hg mL-1, with coefficient of variation (n = 10) of 1.5% at 20 ng Hg mL-1.
Mercury(II) Spectrophotometry Catalysis Calibration Indirect Heated reaction Preconcentration

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

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

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

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

"Influence Of Some Parameters On Membrane Selectivity In Flow Injection Potentiometry"
Izv. Khim. 1990 Volume 23, Issue 2 Pages 167-171
Ilcheva, L.;Yanakiev, R.

Abstract: Selectivity coefficient >1 of commercial Cl--, Br-- and NO3--selective electrodes towards various interfering species in conventional potentiometry can be considerably improved if the electrodes are used as sensors in flow injection analysis. The selectivity can be further improved by increasing the carrier-stream flow rate, decreasing the injection volume, and use of the method of standard additions. The interference from 0.6 mM Br- was thereby overcome when determining ~0.1 to 0.2 M Cl- in seawater by the flow injection technique with a Cl--selective electrode.
Chloride Electrode Potentiometry Selectivity coefficient Membrane Interferences Standard additions calibration

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

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

"Sequential Automatic Online Determination Of Aquiculture Nutrients: Phosphate And Nitrate"
J. Autom. Methods Manag. Chem. 1992 Volume 14, Issue 5 Pages 173-175
P. LINARES, M. D. LUQUE DE CASTRO, and M. VALC&Aacute;RCEL

Abstract: A method was devised for single-channel continuous-flow analysis of NO3- and PO43- in waters with use of a programmable switching valve. For PO43- the reagent was 5% molybdate - 2% ascorbic acid in 2 M HNO3 - glycerol (9:1) and for NO3- the reagent was 0.38% sulfanilamide - 0.144% N-1-naphthylethylenediamine in 4% HCl containing 1.6% NaCl. Rectilinear calibration ranges were 5 to 100 µg mL-1 for NO3- and 1 to 20 µg mL-1 for PO43- and operational ratios of NO3- to PO43- were 1:4 to 100:1 with sampling at up to 45 h-1. The method has been applied to fish-farm seawater.
Phosphate Nitrate Spectrophotometry Valve Automation

"Flow Injection Analysis For Online Monitoring Of Nutrients In Aquaculture"
J. Autom. Methods Manag. Chem. 1992 Volume 14, Issue 5 Pages 181-183
A. C. ARIZA, P. LINARES, M. D. LUQUE DE CASTRO, and M. VALC&Aacute;RCEL

Abstract: Automated normal and reversed flow injection - spectrophotometric methods are described for use in monitoring NH3 and NO2- in tank input and outlet streams at fish hatcheries. The methods are suitable for sampling at up to 40 h-1. Schematic diagrams and operating parameters are given. Rectilinear calibration ranges are 0.5 to 8.5 µg mL-1 (normal) and 0.1 to 2.0 µg mL-1 (reversed) for NO3- and 5 to 80 µg mL-1 (normal) for NH3, with respective coefficient of variation of 3.5, 1.0 and 1.0%. Tolerances of several foreign ions are tabulated. NH3 and NO2- were determined in seawater by photometric flow
Ammonia Nitrate Spectrophotometry Reverse Interferences

"Unsegmented Flow Approach For Online Monitoring Of PH, Conductivity, Dissolved Oxygen And Determination Of Nitrite And Ammonia In Aquaculture"
J. Autom. Methods Manag. Chem. 1994 Volume 16, Issue 2 Pages 59-62
A. C. ARIZA, P. LINARES, M. D. LUQUE DE CASTRO, and M. VALC&Aacute;RCEL

Abstract: Two procedures based on continuous unsegmented techniques have been developed for online measurements of water samples. Monitoring, of pH, conductivity and dissolved oxygen content was achieved with serial detectors. Monitoring of nitrite and ammonia was based on the Greiss diazotization reaction and the Nessler reaction for ammonia with detection for both at 500 nm. Automatic control of a switching valve allowed the change of sample and reagent volumes and detector sensitivity. The photometric detector was independent of salinity allowing analyte to be determined in seawater. Consistent results were obtained between continuous and static measurements on seawater, and the procedures have been used to monitor these parameters in samples taken from a fish farm.
Nitrite Ammonia Conductometry Electrode

"Automation Of Flow Injection Gas Diffusion Ion Chromatography For The Nanomolar Determination Of Methylamines And Ammonia In Seawater And Atmospheric Samples"
J. Autom. Methods Manag. Chem. 1995 Volume 17, Issue 6 Pages 205-212
STUART W. GIBB, JOHN W. WOOD, R. FAUZI, and C. MANTOURA

Abstract: The automation and improved design and performance of Flow Injection Gas Diffusion-lon Chromatography (FIGD-IC), a novel technique for the simultaneous analysis of trace ammonia (NH3) and methylamines (MAs) in aqueous media, is presented. Automated Flow Injection Gas Diffusion (FIGD) promotes the selective transmembrane diffusion of MAs and NH3 from aqueous sample under strongly alkaline (pH > 12, NaOH), chelated (EDTA) conditions into a recycled acidic acceptor stream. The acceptor is then injected onto an ion chromatograph where NH3 and the MAs are fully resolved as their cations and detected conductimetrically. A versatile PC interfaced control unit and data capture unit (DCU) are employed in series to direct the selonoid valve switching sequence, IC operation and collection of data. Automation, together with other modifications improved both linearity (r2 > 0.99 MAs 0-100 nM, NH3 0-1000 nM) and precision (< 8%) of FIGD-IC at nanomolar concentrations, compared with the manual procedure. The system was successfully applied to the determination of MAs and NH3 in seawater and in trapped particulate and gaseous atmospheric samples during an oceanographic research cruise. (33 References)
Ammonia Amines, methyl HPIC Gas diffusion Interface Simultaneous analysis

"A Comparison On The Ammonia-N And Nitrite-N In Aquaculture System Determined By Different Methods"
J. Fish. Soc. Taiwan 1996 Volume 23, Issue 4 Pages 307-321
Huang, Mei Ying; Shyu, Chung Zen; Lu, Min Yih

Abstract: Using the traditional method, FIA (Flow injection analysis), simple-instrument (Spectroquant), kit (Microquant) and simple-test-strip (Reflectoquant), the ammonia-N (unionized plus ionized ammonia as nitrogen) and nitrite-N (nitrite as nitrogen) in aquaculture system were investigated. Twenty fresh water samples (0.09-7.92 mg/l of ammonia-N) were tested for the ammonia-N. The deviations of FIA, Spectroquant and Microquant in comparison with the traditional method were 3.7%, 8.5% and 52.5%, respectively. The underestimation (52.5%) of Microquant must be taken notice by the users. In the Reflectoquant method, the low concentration group was tested with 20 samples (0.3-21.0 mg/l of ammonia-N). The result was by 23.2% higher than the traditional method. The result of high concentration group was by 15.6% lower than the traditional method, as it was tested with six samples (41.0-130.0 mg/l of ammonia-N). There were 21 seawater samples, and their concentration of ammonia-N was 0.02-6.03 mg/l. The deviations of FIA, Spectroquant and Microquant methods was 8.8%, 10.0% and 14.8%, respectively. The nitrite-N in the 23 samples (their concentrations were between 82.5-641.5 µg/l) were determined by traditional method, FIA, Spectroquant and Microquant. The result of FIA and Spectroquant was higher than that of traditional method by 10.1% and 1.3%. On the contrary, Microquant was much lower by 29.2% of which the users should take notice. The Reflectoquant was tested in 19 samples (0.29-7.80 mg/l of nitrite-N), and the result was by 25.4% lower than traditional method. Based on the nitrite-N test of seawater samples, the concentration of nitrite-N in 24 samples was 2.0-2647.2 µg/l by the traditional method, the deviation of FIA and Spectroquant was 0.5% and 4.4%, respectively. The result of Microquant was by 34.4% lower than that of traditional method. In this study, the checking results of Spectroquant, Microquant and Reflectoquant for standard solutions of ammonia-N and nitrite-N were also investigated, the deviations of these three methods were lower than water samples' test.
Nitrogen, ammonia Nitrogen, nitrite Spectrophotometry Method comparison

"Catalytic Determination Of Ultratrace Amounts Of Cobalt By Flow Injection Analysis"
J. Flow Injection Anal. 1985 Volume 2, Issue 1 Pages 40-49
Takuji KAWASHIMA, Takao MINAMI*,Masahumi ATA, Masaakira KAMADA* and Shigenori Nakano

Abstract: A new sensitive catalytic method has been developed for the determination of cobalt by flow injection analysis (FIA). N-Phenyl-p-phenylenediamine is oxidized to a yellow compound at pH 11 by hydrogen peroxide, and this compound is then converted to a blue-green compound(lambda max = 745 nm) with higher absorbance than the yellow compound in an acid solution of pH 0.5. The formation of the yellow compound is catalyzed by cobalt(II) and is extremely accelerated by Tiron(1,2-dihydroxybenzene-3,5-disulfonic acid) as an activator. By this catalytic effect, ultratrace amounts of cobalt can be determined. Sample volume, sampling rate, reaction coil length and reaction variables were examined by FIA. In this FIA method, a linear calibration curve for cobalt(II) was obtained in the range 0.04-0.20 ng/mL and the reproducibility was satisfactory with c.v.(%) of 3.2 and 4.0 for ten determinations of 0.08 and 0.16 ng/mL cobalt(II), respectively. The sampling rate was 30 samples/h. The method was applied to the determination of cobalt in seawater.
Cobalt Spectrophotometry Catalysis Ultratrace

"Flow Injection Hydride Generation Atomic Absorption Spectrometry With A Gas Diffusion Unit Using A Microporous PTFE Membrane"
J. Flow Injection Anal. 1985 Volume 2, Issue 2 Pages 134-142
Manabu YAMAMOTO, Makoto YASUDA, Yuroku YAMAMOTO

Abstract: Performance of a newly made gas diffusion unit with porous PTFE tubing was examined as a gas-liquid separator of FIA manifold for hydride generation-atomic absorption spectrometry. Arsine generated from 0 to 10 ppb of arsenic was separated quantitatively from the sample solutions, when the length of porous PTFE tubing (ID: 3 mm, porosity: 70% ) is longer than 50 cm. Arsenic lower than 2 ppb, which corresponds to the concentration level of arsenic in seawater could be determined directly with a sample volume of 1 mL. Sample throughput was 150/h.
Arsenic Spectrophotometry Gas diffusion Teflon membrane

"Automated Flow-through Analysis Of Trace Elements In Marine Chemistry"
J. Flow Injection Anal. 1996 Volume 13, Issue 1 Pages 3-13
Nakayama, E.

Abstract: A review is presented of automated flow-through analysis of particularly seawater with electrolytic and chelating resin pre-concentration as well as detection by e.g. fluorimetric, chemiluminescence and catalytic methods, especially that suitable for in situ shipboard analysis. (12 references).
Trace organics Chemiluminescence Fluorescence Review Remote instrument Catalysis Preconcentration Chelation Resin

"Determination Of Cobalt In Seawater By Flow Injection Analysis"
J. Flow Injection Anal. 1996 Volume 13, Issue 2 Pages 168-168
Oguma, K.

Abstract: A brief review is presented, which includes techniques especially for in situ flow injection analysis of seawater from various depths from on board the research ship. (5 references).
Cobalt Remote instrument Review

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

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

"Preconcentration And Colorimetric Determination Of Iron(III) By Sequential Injection Analysis"
Lab. Rob. Autom. 1996 Volume 8, Issue 3 Pages 149-156
E. Rub&iacute;, R. Forteza, V. Cerd&aacute;

Abstract: A sequential injection analysis system was developed for the spectrophotometric determination of Fe(III) in fresh and seawater. Water acidified to pH 3-3.5 with HNO3 was injected into the system (flow diagram of instrumental set-up given) and Fe was pre-concentrated on a Chelex 100 microcolumn inserted in the manifold. The Fe retained by the resin was then eluted with 2 M HNO3. At this point, the stream was merged with KSCN stream and the resulting Fe-KSCN complex was detected by monitoring the absorbance changes with a spectrophotometer. The effects of flow rate, pre-concentration column i.d., HNO3 concentration and pH on the determination were investigated. The detection limit was 0.02 mg/l of Fe(III) with an RSD (n = 10) of 3%. Recoveries were >82%. The method was also suitable for drinking water.
Iron Spectrophotometry Sequential injection Preconcentration Chelex

"Flow Injection Online Sorption Preconcentration In A Knotted Reactor For Electrothermal Atomic Absorption Spectrometric Determination Of Ultratrace Amounts Of Cobalt In Natural Waters"
Lab. Rob. Autom. 1997 Volume 9, Issue 4 Pages 191-199
Xiu-Ping Yan, Willy Van Mol, Freddy Adams

Abstract: A flow-injection on-line sorption pre-concentration-electrothermal atomic absorption spectrometric (ETAAS) method has been developed for the determination of ultratrace amounts of cobalt in natural waters. The pre-concentration was achieved by on-line complexation of cobalt with ammonium pyrrolidine dithiocarbamate and subsequent sorption of the complex onto the inner walls of a knotted reactor, made of a 0.5 mm i.d. and 100 cm long PTFE tubing. In order to reduce the eluate volume and to minimize dispersion, an air flow was used to drive the eluent for the elution of the adsorbed analyte and to dispel the eluate into the graphite tube. The adsorbed analyte complex was quantitatively eluted with 45 L of ethanol, and all the ethanolic eluate was successfully introduced at a relatively high flow rate (2.7 mL min-1) into an uncoated polycrystalline graphite tube without need of a platform nor a preheating step. ETAAS determination was performed in parallel with the pre-concentration of the next sample. With a sample consumption of 6.7 mL, an enhancement factor of 47 in comparison with direct injection of 45 L aqueous solution was obtained at a sampling frequency of 31 h-1. The detection limit (3 ) was found to be 2.8 ng L-1. The precision was 3% relative standard deviation (RSD) at the 0.2 g L-1 level (n = 11). The results obtained by the proposed method for a number of water standard reference materials are in good agreement with the certified values.
Cobalt Spectrophotometry Preconcentration Knotted reactor Ultratrace

"A Comparative Study Of Available Procedures For Cobalt Sample Preparation And Introduction Into Atomic Spectroscopic Instruments"
Lab. Rob. Autom. 1998 Volume 10, Issue 3 Pages 151-162
J.M. Mir *

Abstract: Available methods for the continuous pre-concentration and subsequent atomic absorption spectrometric determination of Co in an automated flow injection system are compared in terms of performance. Preconcn. of Co(III) by retention on ion-exchange resins is measured against liq.-liq. extraction, precipitation, and continuous thermospray volatilization following chelation. Reported uses of these online pre-concentration systems for the determination of Co are critically discussed.
Cobalt(III) Mass spectrometry Spectrophotometry Precipitation Preconcentration Solvent extraction Chelation Method comparison

"Determination Of Nitrate And Nitrite In Seawater By Flow Injection Analysis"
Limnol. Oceanogr. 1983 Volume 28, Issue 6 Pages 1260-1266
Kenneth S. Johnson, Robert L. Petty

Abstract: The conventional procedure, in which NO3- are reduced to NO2- for determination as an azo-dye, has been automated by means of a flow injection technique. More than 75 determinations can be made in 1 h, or duplicate determinations on discrete samples can be effected at 30 samples h-1. The detection limit is 0.1 µM, and precision is better than 1% at concentration. >10 µM
Nitrate Nitrite Spectrophotometry Reverse

"Determination Of Hydrogen Sulfide In Seawater Using Flow Injection Analysis And Flow Analysis"
Limnol. Oceanogr. 1986 Volume 31, Issue 4 Pages 894-900
SAKAMOTO-ARNOLD, CAROLE M., KENNETH S. JOHNSON, AND CARL L. BEEHLER

Abstract: The colorimetric determination of H2S by the methylene blue method was automated by using one of the cited methods. Low- and high-sensitivity flow injection analysis manifolds for 200 and 75 µM-H2S, respectively, gave detection limits of 1.2 and 0.12 µM, respectively. The coefficient of variation was <1% at concentration. >10 µM. Sulfide standards were calibrated by colorimetric measurement of the excess of I3- after reacting S2- with iodine.
Hydrogen sulfide Spectrophotometry

"Rapid, Small-volume, Flow Injection Analysis For ΣCO2 And NH4+ In Marine And Freshwaters"
Limnol. Oceanogr. 1992 Volume 37, Issue 5 Pages 1113-1119
HALL, PER 0. J., AND ROBERT C. ALLER

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

"Determination Of Dissolved Manganese In Seawater By Flow Injection Analysis With Colorimetric Detection"
Limnol. Oceanogr. 1993 Volume 38, Issue 6 Pages 1290-1295
MALLINI, LEANNE J., AND ALAN M. SHILLER

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

"Elimination Of Dissolved Sulfide Interference In The Flow Injection Determination Of ΣCO2 By Addition Of Molybdate"
Limnol. Oceanogr. 1995 Volume 40, Issue 5 Pages 1011-1012
LUSTWERK, RIGEL L., AND DAVID J. BURDIGE

Abstract: A previously described flow injection method for the analysis of ΣCO2 included the addition of ZnCl2 to some samples before analysis in order to ppt. dissolved sulfide (which interferes with the method) as ZnS. However, the use of Zn2+ in samples with high concentrations of dissolved sulfide causes the coprecipitation of ZnCO3, and in our experience with this technique, ZnCO3 also preciptates even in the absence of dissolved sulfide. The addition of molybdate effectively complexes dissolved sulfide without interfering with the determination of ΣCO2 by this technique.
Sulfide Conductometry Interferences

"Simultaneous Measurement Of Oxide, Manganese, Iron, Iodide, And Sulfide In Marine Pore Waters With A Solid-state Voltammetric Microelectrode"
Limnol. Oceanogr. 1998 Volume 43, Issue 2 Pages 325-333
Luther, George W., III, Paul J. Brendel, Brent L. Lewis, Bj&oslash;rn Sundby, Lucie Lefran&ccedil;ois, Norman Silverberg, and Donald B. Nuzzio

Abstract: A solid-state Au/Hg voltammetric microelectrode was used to measure, simultaneously and with millimeter spatial resolution, the vertical distributions of O2, Mn2+, Fe2+, HS-, and I- in the pore water of sediments from the Canadian continental shelf and slope. The electrode was used shipboard to analyze undisturbed sediment cores and in a sediment mesocosm to determine the three-dimensional distribution of redox species in the sediment surrounding an actively irrigated worm burrow. In cores from Emerald Basin and Cabot Strait, O2 disappeared and Mn2+, Fe2+, and HS- appeared in the vertical sequence predicted on the basis of thermodynamics. In a core from the Scotian slope, O2 disappeared at ~14-mm depth but Mn2+ was not detected over the 50-mm depth examined with the probe. In all three cores, I- was detected in the pore water below the oxygen-penetration depth. In none of the cores did the distributions of O2 and Mn2+ overlap. The thickness of the layer within which neither O2 nor Mn2+ could be detected ranged from 8 to 40 mm; we suggest that nitrate, not oxygen, is used to oxidize Mn2+. The upwarddirected Mn2+ gradients of 3.5 and 10 mol mm4 in the Emerald Basin and Cabot Strait sediments, respectively, drive manganese fluxes that are more than one order of magnitude lower than the O2 fluxes, which are estimated at 4-S mmol mm 2 d-1. The three-dimensional distributions of solutes in the pore water in the sediment surrounding an irrigated worm burrow demonstrate that both the O2-penetration depth and the depth where Mn2+ is first detected are deeper in the vicinity of the worm burrow than away from it. This is consistent with the notion that irrigation brings oxygenated water into the worm tube, allowing oxygen to diffuse across the burrow wall into the sediment and react with Mn2+ and other reduced porewater constituents. Three-dimensional heterogeneity in porewater composition cannot be detected by conventional one-dimensional coring and slicing techniques. Because these latter techniques average the porewater composition in a large volume of sediment, they may indicate that the distributions of individual species overlap when in fact they do not.
Oxide Manganese Iron Iodide Sulfide Voltammetry Electrode Simultaneous analysis

"Rapid, Highly Sensitive Technique For The Determination Of Ammonia In Seawater"
Mar. Biol. 1986 Volume 91, Issue 2 Pages 285-290
S. W. Willason and K. S. Johnson

Abstract: The water sample is injected into a carrier stream and merges with aqueous NaOH (containing citrate to prevent interference from Ca and Mg), which converts the NH4+ in the sample into NH3. The NH3 diffuses through a hydrophobic PTFE membrane (76 µm thick) into an acceptor stream of aqueous NaCl containing phenol red as indicator. The absorbance of the resulting solution is monitored at 565 nm, and the results are processed by computer. The detection limit is 0.05 µM, and the upper limit is 100 µM. Up to 60 determinations can be carried out in 1 h. Details of the flow system and the diffusion cell are given.
Ammonia Spectrophotometry Gas diffusion Interferences Teflon membrane

"A Mechanized Continuous-flow System For The Concentration And Determination Of Cobalt, Copper, Nickel, Lead, Cadmium, And Iron In Seawater Using Graphite Furnace Atomic Absorption"
Mar. Chem. 1990 Volume 29, Issue 1 Pages 33-46
Kenneth B&auml;ckstr&ouml;m and Lars-G&ouml;ran Danielsson

Abstract: Details are given of an extraction manifold (illustrated) in which the sample is mixed with an extraction reagent containing 0.3% each of ammonium pyrrolidine-1-carbodithioate and diethylammonium diethyldithiocarbamate in 0.75 M NaHCO3 and extracted with 1,1,2-trichloro-1,2,2-trifluoriethane in a falling drop segmentor before passage through an extraction coil and a phase separator. The organic phase is treated with a solution (1 mg mL-1) of Hg in 0.07 M HNO3 as stripping reagent in a second segmentor, the mixture then passes through a second extraction coil and separator. The resulting aqueous back-extract is collected in the sample injector (23 µL) of the interface described previously (Anal. Chem., 1988, 60, 1354) for injection into a Varian AA-1275 instrument equipped with a GTA-95 graphite-tube atomizer; pyrolytically coated graphite tubes (Varian 63-100008-00) with a small internal barrier are used. Temperature programmes for each metal are specified, and contamination problems are summarized. Operation is fully automated apart from loading the sample cups. Sample throughput is 30 h-1. Results on a seawater reference material agreed with certified values for, Co, Cu, Ni and Pb, but were slightly high for Cd and Fe.
Cadmium Cobalt Copper Nickel Lead Iron Spectrophotometry Sample preparation Extraction Automation Reference material Phase separator

"Monitoring Of Labile Copper And Zinc In Estuarine Waters Using Cathodic-stripping Chronopotentiometry"
Mar. Chem. 1991 Volume 34, Issue 3-4 Pages 211-223
C. M. G. van den Berg

Abstract: The sensitivity of cathodic-stripping chronopotentiometry was not affected by variations in salinity or by dissolved O, which rendered this technique suitable for the online automated determination of Cu and Zn in the Tamar estuary. The measurement rate was ~90 samples h-1 and the detection limits were 5 nM and 6 nM for Cu and Zn, respectively. The results agreed with the findings of previous studies. The online measurements eliminated the problem of sample contamination, provided a detailed picture of metal behavior in the estuary and elucidated local inputs. The technique is less sensitive than differential pulse cathodic-stripping voltammetry, but does not require sample filtration or deaeration, which facilitates its application to continuous-flow analysis. The sensitivity was not sufficient, however, to monitor Cu and Zn concentration. in uncontaminated seawater.
Copper Zinc Potentiometry Automation Method comparison Interferences Sensitivity

"Spectrophotometric Determination Of Dissolved Manganese In Natural Waters With 1-(2-pyridylazo)-2-naphthol: Application To Analysis In Situ In Hydrothermal Plumes"
Mar. Chem. 1992 Volume 37, Issue 1-2 Pages 65-82
Carol S. Chin, Kenneth S. Johnson and Kenneth H. Coale

Abstract: In the described flow injection system, the seawater sample (300 µL) is injected into the carrier stream (low-Mn seawater; 0.8 mL min-1), which then merges with a stream of 1-(2-pyridylazo)-2-naphthol - Triton X-100 - borate buffer solution (pH 9.7 to 10.0) containing desferrioxamine to mask Fe (0.15 mL min-1). The combined streams pass to a glass bead mixing column (50 cm) and the absorbance of the resulting solution is measured in a flow-through cell at 560 nm. Temperature and pressure did not adversely affect the sensitivity. The method was tested by application in situ to hydrothermal plumes with use of a submersible chemical analyzer.; the detection limit was ~22 nM.
Manganese Spectrophotometry Triton X Glass beads Single bead string reactor Remote instrument Surfactant

"Iron Distributions In Surface Waters Of The South Atlantic"
Mar. Chem. 1995 Volume 50, Issue 1-4 Pages 13-20
Rodney T. Powell, D. Whitney King and William M. Landing

Abstract: Seawater (2 ml/min) acidified with 6 M HCl was buffered to pH 4.5 and passed onto an immobilized 8-hydroxyquinolene solid-phase column for 2 min. Fe(II) was retained on the column and eluted using a reversed carrier flow of 0.02 M HCl. The carrier and 1 mM luminol reagent in 0.2 M borate buffer of pH 12.6 were mixed to give a pH of 10.5. The Fe(II) was oxidized and this in turn catalyzed the oxidation of luminol producing 426 nm light. The detection has been previously described by King et al. (Environ. Sci. Technol. 1995, 29, 818). Fe concentrations ranged from 0.5-10 nM. Very high Fe concentrations are possible due to high atmospheric input and upwelling. Results are discussed.
Iron(2+) Chemiluminescence 8-Hydroxyquinoline Immobilized reagent

"Determination Of Iron In Seawater By Flow Injection Analysis Using Inline Preconcentration And Spectrophotometric Detection"
Mar. Chem. 1995 Volume 50, Issue 1-4 Pages 3-12
C. I. Measures, J. Yuan and J. A. Resing

Abstract: The method was based upon one described previously by Hirayama and Unohara (cf. Anal. Chem., 60, 2573-2577). Seawater acidified with 6 M HCl (2.5 ml/min) was pumped into the manifold (diagram given) and mixed via a knitted coil with 2 M ammonium acetate buffer to pH 5.2 (0.32 ml/min). The resulting mixture was passed onto a concentration column of resin immobilized 8-hydroxyquinoline where Fe was retained. After loading (~e;1 min), the carrier stream comprising sub-boiled 6 M HCl was passed through the column in the opposite direction to the sample, Fe was released and mixed with 2 M ammonium acetate buffer containing 68.9 µmol of triethylamine and 15% Brij-35 (0.32 ml/min), 3.5 mM NN-dimethyl-p-phenylenediamine (0.06 ml/min) and 0.18 M H2O2 (0.1 ml/min). In the reaction coil, oxidation occurred and the resulting semi-quinone derivatives were detected spectrophotometrically at 514 nm. The detection limit was 0.025 nM-Fe. The RSD (n = 6) was ~e;2.5% at the 0.35 nM level. The method was used to determine Fe in open ocean water and hydrothermal plume samples.
Iron Spectrophotometry Sample preparation Preconcentration 8-Hydroxyquinoline Solid phase extraction Knotted reactor

"Nitrogen And Oxygen Isotopic Composition Of Nitrous Oxide From Suboxic Waters Of The Eastern Tropical North Pacific And The Arabian Sea - Measurement By Continuous-flow Isotope-ratio Monitoring"
Mar. Chem. 1997 Volume 56, Issue 3-4 Pages 253-264
T. Yoshinari*, M. A. Altabet, S. W. A. Naqvi, L. Codispoti, A. Jayakumar, M. Kuhland and A. Devol

Abstract: Water was collected in 20 l Go-Flo bottles, and the dissolved N2O was extracted into stainless-steel tubes packed with molecular sieve 5A. A sample-introduction system for a continuous-monitoring isotope-ratio mass spectrometer (modified from a Finnigan Mat 251 instrument) is shown diagrammatically. A 1/4 in. Pyrex tube is broken in a stream of He (50 ml/min), and the released N2O is carried first through a column of absorbent for CO2, then through an water trap at -60°C, and is itself trapped in a small coil of 1/16 in. o.d. stainless-steel tubing immersed in liquid N2. The coil is warmed in water, the N2O is desorbed in a stream of He (1-5 ml/min), and a portion of the stream is introduced into the mass spectrometer for measurement of the ion currents at masses 44, 45 and 46. Tank N2O of known delta15N and delta18O values was used as working standard. The proposed technique is more convenient than those used hitherto, and involves a much smaller sample without loss of accuracy.
Nitrogen, dissolved Oxygen Mass spectrometry Isotope ratio

"The Determination Of Dissolved Zirconium And Hafnium From Seawater Using Isotope Dilution Inductively Coupled Plasma Mass Spectrometry"
Mar. Chem. 1998 Volume 60, Issue 3-4 Pages 245-255
Brad A. McKelvey* and Kristin J. Orians

Abstract: This paper describes the development of an analytical technique utilizing isotope dilution and inductively coupled plasma mass spectrometry (ICP/MS) to determine the picomolar and femtomolar concentrations of dissolved Zr and Hf found in seawater. Data acquired using this technique are presented to verify the method; in the subarctic North Pacific Zr ranges from 25 to 366 pmol/kg and Hf from 0.20 to 1.02 pmol/kg, with concentrations increasing smoothly with depth. The chelating ion-exchange resin, Chelex-100, was found to be suitable for the extraction/concentration step required for the determination of dissolved Zr and Hf in seawater using isotope dilution analysis. The extraction was optimized for pH, flow rate, resin volume, elution volume, and the time required for isotope equilibration. The isotope ratios 91Zr/90Zr and 178Hf/177Hf were measured using flow injection ICP/MS. The detection limits for a one litre sample are 0.21 and 0.03 pmol/kg for Zr and Hf, respectively. The analytical precision (1s) of the technique improves with increasing concentration and varies from 7% at 42 pmol/kg to 2.5% at 280 pmol/kg for Zr and from 22% at 0.28 pmol/kg to 9% at 1.4 pmol/kg for Hf.
Zirconium Hafnium Mass spectrometry Mass spectrometry

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

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

"Flow Injection Analysis Of Magnesium In Natural Water Using Eriochrome Azurol B"
Nippon Kaisui Gakkaishi 1991 Volume 45, Issue 2 Pages 78-82
Hiroshi NISHIOKA, Tetsu KUMAGAI, Tohru NAGAHIRO, Katsuya UESUGI

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

"Hydrogen Peroxide Determination In Estuarine And Marine Waters By Flow Injection With Fluorescence Detection"
Oceanol. Acta 1995 Volume 18, Issue 3 Pages 353-361
Amouroux D, Donard Ofx

Abstract: The Scopoletin-Peroxidase fluorescence decay method has been developed using standard additions and a flow injection manifold for hydrogen peroxide (H2O2) determination in marine waters. The limit of detection of the method was optimized using stored milli-Q water with a minimum of 5 nM (3s). The method was found to be linear from 5 to 700 nM, with an approximate relative standard deviation of 10%. This accuracy was verified on both milli-Q and natural waters running systematically duplicate analysis. (35 References)
Hydrogen peroxide Fluorescence Optimization Photochemistry Standard additions calibration

"A Technique For The Measurement Of Total Ammonia In Small Volumes Of Seawater And Haemolymph"
Ophelia 1993 Volume 37, Issue 1 Pages 31-40
Hunter, D.A.;Uglow, R.F.

Abstract: A rapid and precise technique combining flow injection analysis and gas diffusion is described for the measurement of total ammonia (NH-3 + NH-4+) in small volumes (100-450 µl) of seawater and diluted haemolymph. Calibration of the method with seawater ammonia standard solution in range 5.0-50.0 µmol ammonia L-1 (n = 6) gave linear calibration curves (r = 0.999 in each case) with precision in the range 0.2-3.0%. Precision of measurement of ammonia in samples of seawater and diluted haemolymph was 0.9-3.3% (n = 11-13). The lower limit of detection is 0.20 µmol ammonia l-1. Thirty determinations can be made per hour.
Ammonia, total Gas diffusion Small sample

"Determination Of Indium In Natural Waters By Flow Injection Inductively Coupled Plasma Mass Spectrometry"
Proc. Indian Acad. Sci. 1998 Volume 107, Issue 4 Pages 359-366
DIA SOTTO ALIBO, HIROSHI AMAKAWA and YOSHIYUKI NOZAKI

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

"Direct Analysis Of Organic-compounds In Water By Membrane Introduction Mass-spectrometry Advances In Selectivity And Interfaces"
Process Control Qual. 1995 Volume 7, Issue 3-4 Pages 117-131
J.S. Patrick, P. Wong, C. Xu, M. Soni, N. Kasthurikrishnan, N. Srinivasan and R.G. Cooks

Abstract: An overview of recent advances in membrane introduction mass spectrometry (MIMS) is presented. Particular attention is given to developments in interfaces, improvements in sensitivity and enhancements in selectivity. A new interface is employed which uses pneumatically assisted transport of the analyte to a jet separator interfaced to a benchtop ion trap mass spectrometer. Affinity MIMS, a new experiment which allows selective trapping of analytes (here benzaldehydes) at a chemically modified membrane, is described. Extended loading times followed by release using a chemical agent yields a limit of detection of 10 ppb for benzaldehyde. Notched broad-band excitation using stored waveform inverse Fourier transform (SWIFT) experiments on a benchtop ion trap is also used to enhance selectivity by permitting injection or retention of selected ions within the ion trap. The combination of SWIFT, signal averaging and extended ionization times has allowed the detection of trans-dichloroethene and toluene at 500 parts-per-quadrillion levels in water with no sample pre-concentration. Tandem mass spectrometry of analytes, introduced by MIMS, is also performed using SWIFT on the benchtop ion trap instrument. Both unimolecular dissociations and ion/molecule reactions can be used to characterize analytes. Trace level(10 ppb) analysis of volatile organics in a seawater matrix is described using flow injection sample handling; the matrix causes no changes in permeation r