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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Selenium

  • IUPAC Name: selenium
  • Molecular Formula: Se
  • CAS Registry Number: 7782-49-2
  • InChI: InChI=1S/Se
  • InChI Key: BUGBHKTXTAQXES-UHFFFAOYSA-N

@ ChemSpider@ NIST@ PubChem

Citations 123

"Determination Of Selenium Balance In Healthy Children By AAS-hydride Generation And By INAA Technique"
Acta Aliment. 2002 Volume 31, Issue 3 Pages 227-234
Adányi, N., Váradi, M., Sziklai-László, I., Snyder, P., Snyder, R. D., Cser, M. Á.

Abstract: Total daily Se intake was determined by duplicate diet collection, venous blood samples were taken and urine was collected over 24 h in order to measure selenium input and output in healthy, American and Hungarian children aged 8 to 17 living in Budapest. The American children consumed not only locally processed food. Food samples were weighed, mixed, homogenised and the Se content was determined by Instrumental neutron activation analysis (INAA). The Se concentration of blood, plasma and urine samples was determined by atomic absorption spectrometry-hydride generation (AAS-HG) after wet digestion. Se intake calculated for wet weight was 62±18.5 µg/day in American children. In the Hungarian children the mean Se intake was about 35% less than in the Americans. Se concentrations in plasma were 0.84±0.16, in whole blood 1.13±0.17 µmol L-1 in the Americans, higher than those in healthy Hungarian children (0.64±0.10 and 0.83±0.12 µmol L-1, respectively) of similar age and gender. Urinary Se output calculated for creatinin was higher in the children from abroad (27.0±9.5 µg Se/day/g creatinin) compared to Hungarians (11.0±5.0 µg Se/day/g creatinin).
Human Blood Plasma Human Urine Spectrophotometry Volatile generation

"Determination Of Selenium In Biological Samples Using ICP-QMS"
Atom. Spectrosc. 2000 Volume 21, Issue 5 Pages 149-155
Boulyga, S.;Dombovari, J.;Becker, J.S.;Dietze, H.J.

Abstract: A method for the determination of selenium traces in plant tissue samples is described. Freeze-dried and homogenized biological samples mere decomposed with HNO3, HF and H2O2 by using closed-vessel microwave digestion under temperature and pressure control. NIST SRM 1577b Bovine Liver and NIST SRM 1547 Peach Leaves reference materials were investigated to optimize the analytical procedure. Selenium concentrations were measured with quadrupole-based inductively coupled plasma mass spectrometry (ICP-QMS) using external calibration and the isotope dilution method. A special solution introduction device combining pneumatic nebulization with hydride generation in the thin liquid film on the walls of the minicyclonic spray chamber was employed for sample introduction into the ICP-MS, which allowed the sensitivity for Se to be increased by up to one order of magnitude without increasing the memory effects. SRMs were doped with different amounts (0, 0.1, 0.2, 0.5 and 1.0 µg/g) of enriched Se-78 spike (98.58% of Se-78) before digestion to study the method performance and selenium losses during sample preparation. For a given matrix selenium losses were reproducible as follows: 9.9±1.6% for Bovine Liver SRM, 15.8±3.6% for Peach Leaves SRM and 20.0±4.5% for the real plant tissue samples. The detection limit for selenium calculated for solid plant tissue was 0.2 µg/g (3s -criteria, m/z=82, digestion 1:1000) using conventional pneumatic nebulization for solution introduction and 0.03 µg/g for a combination of pneumatic nebulization with hydride generation. Applying the method developed, a large number of plant tissue samples were analyzed to study selenium behavior and accumulation in the environment.
NIST 1577 NIST 1547 Mass spectrometry Reference material Volatile generation

"Temporal And Organ-specific Variability Of Selenium In Marine Organisms From The Eastern Coast Of India"
Adv. Environ. Res. 2001 Volume 5, Issue 2 Pages 167-174
Amit Chatterjee, Badal Bhattacharya and Rajdulal Das

Abstract: Temporal and organ-specific variations of selenium concentration in selected coastal organisms (seagrass, bivalves and fish) were investigated in different biotopes of the deltaic Sundarbans, in the eastern coastal region of India. The bivalves and fish were obtained from local fishermen and were destined for human consumption. The samples were digested with HNO3-H2O2 and selenium was extracted from the aqueous solution with triisooctylamine and stripped with dilute hydrochloric acid. The concentration of selenium was measured by hydride generation-atomic absorption spectrometry. The results obtained were verified using inductively coupled plasma-mass spectrometric and fluorometric methods. The mean selenium concentration found in the various species ranged from 0.05 to 3.94 µg g-1 (dry wt.). It was observed that bivalves accumulated more selenium compared to fish and seagrass. The sequence of selenium levels found was, bivalves > fish > seagrass. In seagrass, the selenium concentration was higher in the roots (0.21±0.03 µg g-1; dry wt.) than the stems (0.17±0.02 µg g-1; dry wt.) and the leaves (0.11±0.01 µg g-1; dry wt.). But, in bivalves, the maximum concentration of selenium was found in the gill (3.94±0.11 µg g-1; dry wt.). The results of the analysis of variance indicated that significant differences in Se concentration were evident between seasons and organs in these species. The variations in uptake of selenium may be due to different metabolic requirements for selenium among the three species, variations in food and differences in interspecies retention and elimination mechanisms.
NIST 1566 NIST 1571 NRCC DORM-2 Spectrophotometry Method comparison

"Introduction Of Alcohols In Inductively Coupled Plasma Mass Spectrometry By A Flow Injection System"
Anal. Chim. Acta 1999 Volume 379, Issue 1-2 Pages 175-183
Valderi L. Dressler, Dirce Pozebon and Adilson J. Curtius

Abstract: A flow injection system for the introduction of organic solvents in an instrument of inductively coupled plasma mass spectrometry, using the conventional pneumatic nebulization, is proposed. The instrumental parameters, such as radiofrequency power, nebulization gas flow rate, solution flow rate and time interval between consecutive injections, were optimized for injecting analytical solutions in methanol, ethanol, l-propanol and 1% (v/v) nitric acid in water. In comparison to the conditions for the aqueous solution, a higher power and lower nebulization gas flow rates were adopted for the alcohol solutions. The Ba2+/Ba+ signals ratios are lower in the alcohol solutions, while the CeO+/Ce+ signals ratios are similar in all solvents. The signal intensities for the studied isotopes are enhanced in the organic media, partially due to a criterium used in the optimization, that is, CeO+/Ce+ signal ratio below 3%. The enhancement is specially high for Se, As and Hg. The proposed FIA system, with an injection of a small volume, typically 100 µl, of the organic solvent, on Line diluted 1+1 with water, and the continuous washing with an aqueous solution containing 1% (v/v) nitric acid, between the injections, allows the use of the instrument for more than 200 readings, without reoptimization of the plasma conditions and without visible carbon deposits on the cones. The addition of oxygen to the nebulization gas does not bring a real advantage.
Mass spectrometry Organic solvent Interferences Optimization

"Comparison Of Digestion Methods For The Determination Of Selenium In Fish Tissue By Cathodic Stripping Voltammetry"
Anal. Chim. Acta 2000 Volume 408, Issue 1-2 Pages 97-102
David F. Lambert and Nicholas J. Turoczy

Abstract: A certified reference material (NIST-RM-50 Albacore Tuna) was analyzed for selenium by cathodic stripping voltammetry (CSV), after digestion of the material by a number of methods that avoid the use of perchloric acid. The digestion techniques tested included wet and dry ashing methods, oxygen bomb digestion, ultraviolet (UV) digestion, and methods involving elevated pressure. The only method that reliably produced results that agreed with the certified value for selenium in the reference material was the combination wet/dry ashing method incorporating elevated pressure recommended by the Association of Official Analytical Chemists (AOAC) for determination using hydride generation atomic absorption spectrometry (AAS). Recoveries using the other methods were low and variable, apparently because of incomplete destruction of organic matter and losses caused by volatilisation of selenium.
Fish Tissue NIST 50 Voltammetry Sample preparation Sample preparation Sample preparation Sample preparation Sample preparation Spectrophotometry Reference material Method comparison Standard method

"Combination Of Flow Injection Techniques With Atomic Spectrometry In Agricultural And Environmental Analysis"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 325-340
Zhaolun Fang, Shukun Xu, Xiu Wang and Suchun Zhang

Abstract: A review is presented, with 37 references, in which the applications of the coupled techniques are discussed with emphasis on agricultural and environmental analyzes.
Agricultural Environmental Ion exchange Spectrophotometry Spectrophotometry Spectrophotometry Spectrophotometry Spectrophotometry Review Preconcentration Standard additions calibration

"Study On The Generation Of Hydrogen Selenide And Decomposition Of Tetrahydroborate In Hydride-generation Atomic Absorption Spectrometry"
Anal. Chim. Acta 1986 Volume 188, Issue 1 Pages 127-135
J. Agterdenbos and D. Bax

Abstract: The rate of decomposition of NaBH4 (0.2% in NaOH) by a sample in an acidic medium was investigated under the conditions usual for hydride-generation AAS of Se. The reagent is decomposed within 1 ms of mixing, so H2Se and other hydrides must be formed more rapidly. Bivalent Co, Ni and Cu(II) interfere by catalytic action on BH4- decomposition, resulting in lower hydride formation. The reaction coil used in continuous-flow systems is not necessary for completion of the reaction, but it contributes to the separation of the volatile hydride from the liquid phase before transport to the heated cell, thus giving better recoveries.
Spectrophotometry Kinetic Interferences Volatile generation Volatile generation

"Determination Of Arsenic And Selenium In Coal By Continuous-flow Hydride-generation Atomic Absorption Spectrometry And Atomic Fluorescence Spectrometry"
Anal. Chim. Acta 1987 Volume 194, Issue 1 Pages 177-187
Les Ebdon and John R. Wilkinson

Abstract: Powdered coal (0.7 g) was digested with 72% HClO4 with cautious heating (and quenching in iced water if ignition appeared imminent) until all carbonaceous material had dissolved and was then heated under reflux for a further 10 min. After cooling, the solution was transferred, with washing with 5 M HCl, to a 50 mL flask. In order to remove interfering metal ions, portions (10 to 20 ml) of the digest were transferred to a PTFE centrifuge tube and 2 mL of 10% LaCl3 solution was added followed by 1 mL of either 10% NaI solution (for As) or 10% NaBr solution (for Se). The mixture was cooled, centrifuged, and treated with further 10% LaCl3 solution, the supernatant solution was discarded and the ppt. was dissolved in 5 M HCl and diluted to volume Hydride-generation AAS or AFS was used to determine As or Se; the AFS detection limit was 25 or 10 ng g-1, respectively.
Coal Fluorescence Spectrophotometry Interferences

"Determination Of Selenium By Means Of Computerized Flow Constant-current Stripping At Carbon Fiber Electrodes. Application To Human Whole Blood And Milk Powder"
Anal. Chim. Acta 1987 Volume 197, Issue 1 Pages 257-264
Chi Hua, Daniel Jagner and Lars Renman

Abstract: The main features of the flow constant-current stripping analysis for selenium(IV) are formation of a mercury film on a carbon fiber sensor in a chloride medium containing mercury(II), electrolysis in the sample at -0.20 V vs. SCE for 15-60 s, and subsequent stripping (reduction) of the mercury(II) selenide formed on the electrode surface, by means of a constant current of 0.40 µA in an acidic magnesium chloride solution containing Triton X-100. During stripping, the potential vs. time gradient is monitored at a real-time measuring rate of 25.6 kHz. All experimental parameters are under computer control. A standard addition method is used and the results are calculated and reported, both digitally and graphically. Equations relating the magnitude of the constant current to the concentration of reducible species, and, in particular, of dissolved dioxygen, are derived. Milk powder and whole blood reference samples were analyzed by high-pressure digestion in nitric acid and dilution with hydrochloric acid, in order to reduce selenium(VI) to selenium(IV), and then constant-current stripping. The results obtained by this method were lower than those obtained by the reference technique, but the values agreed within one standard deviation of the two techniques. Ions, such as iron(III) and lead(II), known to interfere with electrochemical stripping for selenium(IV) in batch analysis did not interfere in the flow approach.
Whole Human Powder Amperometry Electrode Computer

"Reductive Stripping Chronopotentiometry For Selenium In Biological Materials With A Flow System"
Anal. Chim. Acta 1987 Volume 198, Issue 1 Pages 231-237
H. Eskilsson and C. Haraldsson

Abstract: Reductive stripping chronopotentiometry in a flow system is used for determination of selenium in mussels and NBS bovine liver after acid digestion. The automated flow system contains a thin-layer cell with a mercury film electrode. In the deposition step, mercury(II) selenide is formed on the mercury film surface; the stripping step involves reduction to mercury and hydrogen selenide. This reduction is done in a separate solution of almost saturated calcium chloride, which eliminates interferences from oxygen so that solutions need not be deoxygenated. The detection limit is 0.14 µg L-1 selenium at a deposition time of 120 s.
Biological material Potentiometry

"Online Separation And Preconcentration In Flow Injection Analysis"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 41-55
Zhaolun Fang, Zhaohai Zhu, Suchun Zhang, Shukun Xu, Lei Guo and Lijing Sun

Abstract: A review is presented of developments in flow injection analysis that involve separation and pre-concentration. by gas diffusion, ion exchange or liquid - liquid extraction. Several inorganic illustrations of each principle are given, mainly of their use as a preliminary stage before determination by AAS. (44 references).
Ion exchange Spectrophotometry Spectrophotometry Spectrophotometry Spectrophotometry Sample preparation Extraction Gas diffusion Preconcentration Review

"Flow Injection Analysis Of Trace Elements By Use Of Catalytic Reactions"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 167-182
Takuji Kawashima*, Shigenori Nakano

Abstract: This review covers the mechanism of catalytic reactions involving trace elements, together with catalytic flow injection methods for the determination of Fe, Mn, Cu, Co, V, Cr, Mo and Se, as well as halides and other anions. Representative examples are given of organic compounds used in the indicator reactions. Comparison with batch methods shows that flow injection methods are sometimes less sensitive than their manual counterparts, but afford satisfactory accuracy and precision and have certain advantages (94 references). A review with 94 references. Catalytic reactions have importance in trace analyzes for elements, and kinetic-catalytic methods of anal. based on catalytic reactions have progressed recently. The change in a phys. property such as absorbance, fluorescence, chemiluminescence or electrode potential of a system with time is usually monitored in kinetic-catalytic methods, as these methods include time as a measured variable. Flow injection analysis (FIA) is considered to be a suitable technique for catalytic methods of analysis, i.e., the reaction can easily be controlled by fixing the flow rate of solutions and the length of the reaction coil, yielding reproducible mixing. The adaptation of FIA to catalytic methods can lead to many advantages such as higher precision, better detection limits and rapid sample throughput. After a brief review of the catalytic action of elements in redox reactions, the use of the catalytic reactions in FIA methods is discussed through representative examples.
Fluorescence Chemiluminescence Spectrophotometry Electrochemical analysis Review Catalysis Method comparison

"Multivariate Correction Of Chemical Interferences In Hydride-generation Atomic Absorption Spectrometry"
Anal. Chim. Acta 1992 Volume 268, Issue 1 Pages 115-122
Günter Henrion*, René Henrion, Ralph Hebisch and Birgit Boeden

Abstract: A mixture of simultaneously occurring elements, as exemplified by Se, Sb and As, was used to investigate chemical interferences. Measurements in batch mode were made with an AAS 30 spectrometer (Jenoptik, Jena), equipped with a hydride-generation system and an electrically heated quartz tube atomizer. Continuous-flow measurements were made on a Perkin-Elmer model 300 instrument with a quartz tube atomizer. Aqueous NaBH4 stabilized with 1% of NaOH was used as reductant, and the HCl was cleaned by sub-boiling distillation. To establish the effect of chemical interference, a training data set was established according to a factorial design for 64 synthetic samples. It was found that the system is dominated by Se - As interference. Multicomponent calibration by any accepted method of multivariate regression can effectively correct the systematic errors of measurement. As goodness of prediction is stable over time, the factorial design, once established, can be applied in routine analyzes. Generalization to more complex systems should be straightforward.
Spectrophotometry Interferences Multivariate calibration Factorial design

"Determination Of Arsenic And Selenium In Environmental Samples By Flow Injection Hydride-generation Atomic Absorption Spectrometry"
Anal. Chim. Acta 1992 Volume 270, Issue 1 Pages 231-238
Chris C. Y. Chan* and Ram S. Sadana

Abstract: Environmental samples such as soil, vegetation, water, sediments and industrial wastes were digested (except for water) by heating at 200°C with HNO3 - H2SO4 - HClO4 (6:3:1). The cooled digest or water was treated with concentrated HCl to reduce Se6+ to Se4+; for As analysis the solution was treated with 10% KI - 1% ascorbic acid (10:1) to reduce As5+ to As3+. The analytes were converted to the hydrides with 1% NaBH4 in an automated hydride-generation system. A stream of Ar (3 mL min-1) carried the evolved hydride via a gas - liquid separator and an impinger to a heated quartz tube atomizer for analysis by AAS. The effects of the experimental variables are discussed. Interference by Cu and Ni on the determination of Se was masked with 1,10-phenanthroline. The detection limits for both As and Se were 0.3 ng mL-1. The coefficient of variation was 2.6% for As in a sediment (n = 10) and 2% in water (n = 5); similar precision was obtained for Se. The results for the standard reference materials agreed closely with their certified values. Flow injection analysis is applied to sample introduction in conjunction with automated hydride generation and AAS for the determination of As and Se in environmental samples such as soil, vegetation, waters, sediments, and industrial wastes. A large sample loop was used to provide high sensitivities with an absorbance of 0.4 for 10 ng mL-1 for both As and Se. The samples, except waters, are digested with a mixture of nitric, sulfuric, and perchloric acids. Se6+ in the digested solutions is pre-reduced to Se4+ by exothermic reaction in 6-8 M HCl solution, and As5+ to As3+ by reacting with KI. The analyte is then converted to hydride by NaBH4 in an automated hydride generation system. The evolved hydride is carried through to a heated quartz tube by a stream of argon, and the atomic absorption of the analyte is measured. 1,10-Phenanthroline is used as masking agent to control interferences from Cu and Ni on Se. The detection limits for both As and Se are 0.3 ng mL-1, equivalent to 75 ng g-1 in solid sample. Precision is 2.6% RSD Results for standard reference materials agree closely with the certified values.
Environmental Environmental Environmental Vegetable Waste Spectrophotometry Reference material Interferences Volatile generation Volatile generation

"Different Sample Introduction Systems For The Simultaneous Determination Of Arsenic, Antimony And Selenium By Microwave-induced Plasma Atomic Emission Spectrometry"
Anal. Chim. Acta 1993 Volume 271, Issue 1 Pages 171-181
E. Bulska and P. Tschöpel*, J. A. C. Broekaert, G. Tölg

Abstract: The determination of hydride-forming elements using different sample introduction procedure into microwave-induced plasmas (MIPs) has been studied. For the determination of As, Sb and Se analyte introduction was accomplished with a pneumatic concentric glass nebulizer,a graphite furnace, or with thydride generation followed by cold-trapping or hot-trapping in a graphite furnace. The detection limits obtained with different types of low power MIPs (toroidal, 1 or 3 filament MIPs) operated in a TM010 cavity according to Beenakker also were investigated. The construction of the flow system used for pre-concentration and the effects of reagent concentration, gas flow rates as with MIP-atomic emission spectrometry (AES) were investigated. The trapping of the hydrides followed by their vaporization showed substantial advantages over the other introduction systems investigated, especially with respect to power of detection. Further, mutual interferences being a big problem in atomic absorption spectrometry are widely absent in MIP-AES. Under compromise operating conditions the detection limits for As, Sb and Se are 0.4; 0.35; 0.25 ng mL-1 respectively, while the sample volume can be varied from 0.05 mL up to several milliliters.
Spectrophotometry Simultaneous analysis Volatile generation Volatile generation

"Simultaneous Determination Of Arsenic, Antimony And Selenium By Gas-phase Diode-array Molecular Absorption Spectrometry, After Preconcentration In A Cryogenic Trap"
Anal. Chim. Acta 1995 Volume 300, Issue 1-3 Pages 321-327
Susana Cabredo Pinillos, Jesús Sanz Asensio* and Javier Galbán Bernal

Abstract: Solutions of 4% NaBH4 (4 ml/min) and analyte mixture in 0.5 M HCl (35 ml/min) were passed through a mixer and to a system of two gas-liquid separators where the N2 carrier gas (20 ml/min) transferred the gaseous products to a water trap immersed in a bath of ice and salt (-10°C). The hydrides were retained in a glass U-tube in liquid N2. After trapping, the tube was removed from the cryogenic bath for > 5 min then heated for 1 min at 80°C. The hydrides were transported to a continuous-flow cell and placed in a diode-array spectrophotometer for measurement of the transient signals over the 190-250 nm range. Linear response ranges above 50 µg/l for As(III), 30 µg/l for Sb(III) and 200 µg/l for Se(IV) were obtained with detection limits of 22, 15 and 65 µg/l, respectively. Multiwavelength linear regression equations were used for the simultaneous determination of the three elements in synthetic samples and to study the effects of possible interfering species. The results were similar to those obtained by other hydride generation techniques.
Spectrophotometry Gas phase detection Interferences Preconcentration Cold trap

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

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

"Determination Of Arsenic And Selenium In Spinach And Tomato Leaves Reference Materials Using Flow Injection And Atomic Absorption Spectrometry"
Talanta 1994 Volume 41, Issue 10 Pages 1785-1790
Rajananda Saraswati and Robert L. Watters, Jr.*

Abstract: Dried tomato or spinach leaves were refluxed for 4 h with HNO3 and H2SO4, the solutions were cooled, HClO4 was added and the solution heated for 5 h until dense fumes appeared. After cooling, HCl was added, the solutions were heated for 15 min at near boiling and allowed to cool. The digests were diluted with water and a portion was mixed with a reducing agent comprising 10% KI and 5% ascorbic acid for 1 h to reduce As(V) to As(III). A second portion of diluted digest was heated with 1:1 HCl in a water bath at 90°C for 25 min to reduce Se(VI) to Se(IV). Using 5% HCl as a carrier stream (10 ml/min) in the FIA system the sample was swept from the injection loop (200 µL) to a mixing coil (11 cm) where it reacted with a reductant solution of 2.5 g/l of NaBH4 in 0.05% NaOH (6 ml/min). The gaseous hydrides of arsenic and selenium are separated from the solution and swept by Ar gas to a quartz absorption cell heated at 900°C in the light path of an electrodeless discharge lamp in an AAS for determination at 193.7 and 196 nm for As and Se, respectively. Calibration graphs were linear for 0-5 ng/ml of As or Se with detection limits of 0.15 and 0.17 ng/ml, respectively.
Plant Spectrophotometry

"Spectrophotometric Determination Of Selenium(IV) And Selenium(VI) With Flow Injection"
Analyst 1986 Volume 111, Issue 12 Pages 1405-1407
Pilar Linares, María Dolores Luque de Castro and Miguel Valcárcel

Abstract: The determination depends on the catalytic action of Se(IV) in the reaction between NaClO3, hydrazine and o-tolidine in a HCl medium. The reagents are mixed with the sample solution by a simple flow injection manifold. The absorbance of the resulting solution is monitored at 440 nm. The detection range is 1 to 12 µg mL-1 of Se(IV) or Se(VI) (reduced by prior boiling with concentrated HCl), with a sampling rate of 90 h-1. Various interfering ions have been studied and their tolerance levels are given.
Spectrophotometry Interferences

"Flow Injection Spectrophotometric Determination Of Selenium Based On The Catalysed Reduction Of Toluidine Blue In The Presence Of Sulfide Ion"
Analyst 1989 Volume 114, Issue 6 Pages 715-717
Carmen Martinez-Lozano, Tomás Pérez-Ruiz, Virginia Tomás and Concepción Abellán

Abstract: A stream of 0.003% toluidine blue solution is mixed with a stream of alkaline 5 mM S2- containing 0.01 M BaNa2EDTA and 4% of formaldehyde (both 0.74 mL min-1), sample solution (80 µL) is injected into a carrier stream of aqueous 4% formaldehyde (0.74 mL min-1), and the two streams merge before passing to a 400-cm mixing coil. After 30 s, the flow stops for 30 s and the solution is pumped to a detector for absorbance measurement at 620 nm. The calibration graph is rectilinear for 0.2 to 2 µg of Se and the detection limit is 0.08 µg. The coefficient of variation (n = 11) for a 0.56 µg sample was 0.01%. The method was applied to ores and pharmaceuticals.
Geological Pharmaceutical Spectrophotometry Catalysis Stopped-flow

"Determination Of Selenium In Blood Plasma And Serum By Flow Injection Hydride Generation Atomic Absorption Spectrometry"
Analyst 1990 Volume 115, Issue 3 Pages 275-278
Kieran McLaughlin, Darioush Dadgar, Malcolm R. Smyth and Dorothy McMaster

Abstract: A flow injection hydride generation atomic absorption spectrometric (AAS) method has been used to determine the selenium concentrations of human serum and plasma samples following digestion with nitric, sulfuric and perchloric acids. In the hydride generation process, reduction was carried out by sodium tetrahydroborate to produce a hydride that was atomized in a flame-heated atomisation cell. The method had a detection limit of 1.2 ng mL-1 and a sensitivity of 2.1 ng mL-1. Within-run precisions of 5.8% at 20 ng mL-1 and 4.5% at 80 ng mL-1, and between-run precisions of 4.8% at 69 ng mL-1 and 3.4% at 80 ng mL-1 were obtained. An inter-laboratory comparison study with a graphite furnace AAS method was carried out and the results showed excellent agreement. The flow injection method of sample introduction allowed the use of a sample volume of 330 µL with an injection rate of 90 injections per hour. Plasma or serum (2 ml) was digested at 140°C for 20 min (temp. raised to 140°C over 20 min) with 5 mL of 16 M HNO3 and cooled; 2.5 mL of 18 M H2SO4 and 1 mL of 11.6 M HClO4 were added and the temperature was increased to 140°C (held for 15 min), then to 205°C over 15 min (held until white fumes appeared). The residue was cooled, then heated at 95°C for 30 min with 5 mL of 5 M HCl. After cooling and dilution to 25 mL with water, a 330 µL portion was injected into the flow injection hydride generator with 1% (w/v) NaBH4 (3.9 mL min-1) - 1 M HCl (5.4 mL min-1). The H2Se produced was carried by the Ar stream to the heated silica cell of the AAS instrument and atomized at 900°C. Absorbance was measured at 196 nm. The detection limit of Se was 1.2 ng mL-1; sensitivity was 2.1 ng mL-1. Within- and between-run precisions were 4.5 and 3.4%, respectively, at 80 ng mL-1 of Se. Recoveries were 95 to 109%. Results from an inter-laboratory comparison study with graphite-furnace AAS agreed well.
Blood Plasma Blood Serum Spectrophotometry Sample preparation Detection limit Graphite Dilution Sensitivity

"Combined Generator/separator For Continuous Hydride Generation: Application To Online Pre-reduction Of Arsenic(V) And Determination Of Arsenic In Water By Atomic Emission Spectrometry"
Analyst 1992 Volume 117, Issue 3 Pages 407-411
an D. Brindle, Hosen Alarabi, Samir Karshman, Xiau-chun Le, Shaoguang Zheng and Hengwu Chen

Abstract: A continuous hydride generator is described which incorporates a combined generator/separator. The low acid concentrations necessary in the tetrahydroborate(III)-L-cysteine mediated determination of most hydride-forming elements require that the gas is purged from solution As the hydride transfer reaction is so rapid, this allows both the hydride-forming reaction and the stripping reaction to take place in the same vessel. The system has been further modified to allow online pre-reduction. of As(V) to As(III) by L-cysteine. Detection limits for As, Ge, and Se are 4, 0.3 and 9 ng/mL, respectively, at a sample flow rate of 15 mL/min. Application of the system to the determination of As in water is described. Concentrations of As in several Ontario waters were 7-600 ng/mL. Interferences from Ni and Pd, two of the most strongly interfering elements in the continuous hydride generation process, are diminished to a greater extent with the system described here than with the conventional high acid continuous system.
Environmental Spectrophotometry Volatile generation Interferences Optimization Volatile generation

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

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

"Comparison Of Reflux And Microwave Oven Digestion For The Determination Of Arsenic And Selenium In Sludge Reference Material Using Flow Injection Hydride-generation And Atomic Absorption Spectrometry"
Analyst 1995 Volume 120, Issue 1 Pages 95-99
Rajananda Saraswati, Thomas W. Vetter and Robert L. Watters Jr.

Abstract: Sludge (0.25 g) was mixed with 5 mL concentrated HNO3 and 5 mL concentrated H2SO4, and a five-stage microwave oven digestion procedure (details tabulated) was used to digest the sample. The maximum temperature and pressure reached during the digestion were 175°C and 190 psi, respectively. The resulting solution was heated on a hot-plate until all the HNO3 was removed, and then diluted to 100 mL with 2% HCl. For As determination, 10 mL of the solution were treated with 5 mL of a solution of 10% KI and 5% ascorbic acid for 1 h before analysis. For Se determination, 10 mL of the solution was diluted to 100 mL with HCl (1:1), followed by heating at 90°C for 25 min before analysis. Analyses were performed by injecting the sample solution (40 µL) into a carrier stream of 10% HCl for subsequent reaction with a solution of 0.25% NaBH4 in 0.05% NaOH. The gaseous hydrides of As or Se produced were analyzed by AAS at 193.7 or 196 nm, respectively. Calibration graphs were linear from 5-20 and from 2-10 ng/ml of As and Se, respectively. The corresponding detection limits were 0.15 and 0.17 ng/ml. Microwave oven digestion with HNO3/H2SO4 provided results comparable to those obtained by reflux column digestion using HNO3/H2SO4/HClO4 and afforded shorter sample preparation times.
Sludge Sample preparation Spectrophotometry Reference material Method comparison

"Effect Of High Salt Concentrations On The Determination Of Arsenic And Selenium By Flow Injection Hydride Generation Electrothermal Atomic Absorption Spectrometry"
Analyst 1998 Volume 123, Issue 8 Pages 1697-1701
Robert I. Ellis, Nils G. Sundin, Julian F. Tyson, Susan A. McIntosh, Christopher P. Hanna and Glen Carnrick

Abstract: In the determination of As and Se by flow injection hydride generation ETAAS, the presence of up to 20% NaCl enhanced the signals for 20 µg L-1 As and Se by up to 28%. The enhancement was obtained with a variety of gas-liq. separators. A systematic study of the possible causes of the signal enhancement in the determination of Se was undertaken, from which the effect originated in the processes responsible for the distribution of the H selenide between the solution and gas phases. Processes related to the transport of the analyte from the gas-liq. separator and the trapping of the analyte on the interior of the atomizer were not affected by the presence of dissolved salts. As Na is transported to the atomizer, aqueous aerosol was deposited in the atomizer, although the quantities were irreproducible. The enhancement could be eliminated by increasing the borohydride concentration. However, with the small volume gas-liq. separator, this latter approach was limited because of carry-over of liquid to the atomizer. The effect could be compensated for by adding up to 40% (m/v) of salt to the borohydride reagent.
Spectrophotometry Ionic strength Dissolved solids Phase separator Signal enhancement

"Use Of Flow Injection For Inline Elimination Of Interferences In Hydride Generation Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1990 Volume 5, Issue 8 Pages 681-686
Graham D. Marshall and Jacobus F. van Staden

Abstract: A modified version of the flow injection system described previously (Ibid., 1990, 5, 685) was used to remove interference from (i) As(V) or Sb(V) in the determination of As or Sb, respectively, by reduction of the sample with KI, (ii) noble metals in the determination of Se, As and Bi by masking with Te(IV) and (iii) base metals, e.g., Ni(II), in the determination of As and Se by ion-exchange chromatography on a Bio-Rad AG50W-X8 column. In the determination of 0.4 µg mL-1 of Se, e.g., interference from up to 0.1 mg mL-1 of Pb was eliminated by reacting the sample with a stream of 4.8 M HCl containing 0.2 mg L-1 of Te(IV) (2 mL min-1) before reduction with NaBH4.
Spectrophotometry Interferences

"Elimination Of Copper Interference By Continuous-flow Matrix Isolation In The Determination Of Selenium By Flow Injection Hydride-generation Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1991 Volume 6, Issue 2 Pages 133-138
Stephen G. Offley, Nichola J. Seare, Julian F. Tyson and Helen A. B. Kibble

Abstract: For removal of Cu from the sample solution for determination of Se by the cited technique, a mini-column (5 cm x 3 mm) of Dowex 50W-X8 strongly acidic cation-exchange resin was incorporated into the flow system. The mini-column manifold and hydride-generation manifold were made independent of each other to achieve optimum performance for each step. After removal of Cu, a 400 µL aliquot of sample solution was injected into the carrier stream (H2O) for determination of Se. Periodic regeneration of column with 1 M HCl obviated the need for repacking, without loss of resin efficiency. The method was applied to the determination of 36 and 479 µg g-1 of Se in two standard coppers. The system had a sample rate of 51 h-1, a detection limit of 2.1 ng mL-1, and a coefficient of variation (n = 12) of 1.5% at 10 ng mL-1.
Spectrophotometry Column Interferences Resin Matrix removal

"Flow Injection - Electrochemical Hydride-generation Technique For Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 2 Pages 287-292
Yuehe Lin, Xiaoru Wang, Dongxing Yuan, Pengyuan Yang, Benli Huang and Zhixia Zhuang

Abstract: A flow injection - electrothermal hydride generation technique for AAS has been developed in order to avoid the use of sodium tetrahydroborate, which is capable of introducing contamination. A specially designed thin-layer electrolytic flow cell (diagram given) for hydride generation was used in a normal flow injection system coupled to an electrically heated T-tube atomizer for atomic absorption measurements. The sample was injected into the electrolyte carrier stream flowing to the electrolytic cell, where hydride-forming elements were reduced to gaseous hydrides. The effects of factors such as the eletrode material, electrolyte, current density and carrier stream flow rate, on the rate of formation of the hydride and interferences were studied. The technique was used to determine of As in mangrove leaves, Se in traditional Chinese medicines and Sb in polyester film. The detection limits were 0.45, 0.62 and 0.92 ng mL-1 of As, Se and Sb, respectively.
Leaves Chinese Spectrophotometry Electrochemical product generation Volatile generation Interferences Volatile generation

"Use Of A Flow Injection Hydride-generation Technique In Non-dispersive Atomic-fluorescence Spectrometry"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 4 Pages 667-674
Tiezheng Guo, Mingzhong Liu and Werner Schrader

Abstract: Parameters were established for the determination of As, Sb, Bi, Hg, Se and Te. The optimum NaBH4 concentration was 0.4% except for As (0.7%), with a flow rate of 400 to 500 mL min-1 of Ar and a furnace temperature of ~750°C. The calibration graphs were rectilinear within ranges up to 300 µg L-1, and the detection limits were between 0.02 and 0.2 µg L-1. The coefficient of variation ranged from 1 to 2%. The feasibility of using a flow injection (FI) hydride generation technique in conjunction with atomic fluorescence spectrometry (AFS) was investigated. Parameters were established for the determination of Sb, As, Bi, Hg, Se, and Te. Among the parameters that were found to have a more pronounced influence on performance were the concentration. of NaBH4, the carrier gas flow, the observation height, and the temperature of the atomizer cell. Compared with the manual sampling system (or batch system), the relative detection limits of the FI combination were better by factors of 2.5-10. By using FI, the sample volume was reduced to 500 µL, hence, the absolute detection limits were even better with improvements of between 10- and 50-fold depending on the element. The absolute detection limit for Se using the FI technique was 0.035 ng, while with the batch system it was 0.8 ng. Similarly, Hg detection limits with the FI technique and the batch system were found to be 0.015 and 0.4 ng, respectively. The best improvement in the abs. detection limits was found for Te, which with the FI technique was 0.02 ng while with the batch system it was 1.0 ng. The linear ranges were typically 2-3 orders of magnitude of analyte concentrations, which is much wider than that of atomic absorption spectrometry. Sampling frequency was typically 120 injections per h, and since a double-channel AFS instrument was used in this work, pairs of elements such as As, Sb and Bi, Hg were measured simultaneously, which equates to 240 measurements per h. The technique was applied to the determination of hydride forming elements in geological reference materials.
Geological Fluorescence Fluorescence Optimization Reference material Simultaneous analysis Linear dynamic range

"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.
River Sea Fluorescence Volatile generation Reference material Phase separator Optimization Interferences Volatile generation

"Determination Of Selenium And Arsenic In Mineral Waters With Hydride-generation Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1994 Volume 9, Issue 3 Pages 285-290
Marjan Veber, Ksenija Cujes and Sergej Gomiscek

Abstract: Water was filtered (0.45 µm) and acidified (HCl). For As, a 5-25 mL sample was treated with 4 mL of concentrated HCl and 1 mL each of aqueous 1% ascorbic acid and aqueous 20% KI, whereas for Se a 15 mL sample was treated with 10 mL of HCl and heated at 90°C for 12 min. After dilution to 50 ml, hydrides were generated [typical sample and reagent (1% NaBH4 solution in 1% NaOH) flow rates 10 ml/min] in a 75-100 cm x 1 mm i.d. reaction coil. After gas-liquid separation with Ar as carrier gas (40 l/h), continuous-flow determination was performed by electrothermal AAS. In situ pre-concentration was also performed with reagent and sample flow rates of 0.5 ml/min and an Ar flow rate of 5 l/h, the graphite surface being pre-conditioned by drying 50 µL of 10^-5% Pd solution Under continuous-flow conditions, standard-addition calibration was linear for 1-50 µg/l of As and Se with detection limits of 0.15 µg/l and RSD 5%. With pre-concentration, detection limits of 0.02 µg/l were obtained, with RSD of 2-16%. Recoveries of 10 µg/l of As and 0.5-1 µg/l of Se were satisfactory. Mg, Na and sulfate interfered.
Mineral Spectrophotometry Spectrophotometry Sample preparation Interferences Preconcentration

"Determination Of Arsenic, Chromium, Selenium And Vanadium In Biological Samples By Inductively Coupled Plasma Mass Spectrometry Using Online Elimination Of Interference And Preconcentration By Flow Injection"
J. Anal. At. Spectrom. 1994 Volume 9, Issue 5 Pages 611-614
Les Ebdon, Andrew S. Fisher and Paul J. Worsfold

Abstract: A 0.5 g portion of the biological material was digested with 3 mL of HNO3 and 2 mL of water for 16 h and then irradiated in a microwave oven at 300 W for 3 min. After cooling, 0.1 g of potassium persulfate was added and the digest was microwaved at 300 W for a further 2 min; H2O2 (1 ml) was then added and the digest was irradiated with a 150 W Xe lamp for 18 h to decompose arsenobentaine. The digest was diluted to 50 mL with Tris buffer (pH 9) following the addition of 3 mL of 60% NaOH. A 200 µL portion of this solution was injected into the water carrier stream (1.5 ml/min) of the flow manifold and passed through the alumina column (2.5 cm x 3 mm i.d.). The analytes were subsequently eluted from the column by injecting 200 µL of 1 M HNO3 into the carrier stream and determined by ICP-MS. The detection limits for V, Cr and As were 0.12, 0.6 and 0.9 µg/g. To achieve a detection limit of 1 µg/g for Se it was necessary to use an alternative procedure which involved the pre-concentration of 10 mL of digest. The recoveries of 60 ng/ml of Cr, Se and V and 600 ng/ml of As from a spiked biological reference material (Tort-1, lobster hepatopancreas) were 98-109%, respectively.
Biological material Mass spectrometry Reference material Preconcentration Interferences

"Determination Of Selenium In Fruit Juices By Flow Injection Electrothermal-atomization Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1994 Volume 9, Issue 5 Pages 657-662
Marco A. Z. Arruda, Mercedes Gallego and Miguel Valcárcel

Abstract: An automatic flow injection method for the determination of Se in fruit juices by graphite-furnace AAS was described. The flow injection manifold allowed the dilution of the fruit juice, the addition of a chemical modifier and the delivery of the filtered juice to the autosampler cup. A 200 µL portion of the fruit juice slurry (spiked with 5-30 µg/l of Se for standard addition calibration) was injected into a 0.2% HNO3 carrier solution (0.5 ml/min) which was then merged with a 0.01 M palladium nitrate chemical modifier stream (0.5 ml/min). The mixture was passed through a paper filter (Whatman No.1) and a mixing chamber and collected in the autosampler cup. To determine the total Se in the fruit juice slurry the filter was by-passed. Se was determined at 196 nm (furnace temperature program given). Calibration graphs were linear for 50-500 µg/l of Se and the detection limit was 5 µg/l. The RSD for 20 µg/l Se in orange juice were 4% (within-day) and 11.1% (between-day). The method was applied to commercial fruit juices. The Se contents of the slurries and filtrates were 15-150 and 14-102 µg/l, respectively, with 60-90% of the Se in the liquid phase.
Fruit Spectrophotometry Slurry

"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-García, Nerea Bordel-García 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.
Sea Spectrophotometry Volatile generation Volatile generation

"Use Of Thiourea In The Determination Of Arsenic, Antimony, Bismuth, Selenium And Tellurium By Hydride Generation Inductively Coupled Plasma Atomic-emission Spectrometry"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 5 Pages 405-408
Hilde Uggerud and Walter Lund

Abstract: A study was made of thiourea as an agent for the pre-reduction and masking of interferences in the multi-element determination of arsenic, antimony, bismuth, selenium and tellurium by hydride generation inductively coupled plasma atomic emission spectrometry. Thiourea reduces arsenic and antimony from the pentavalent to the trivalent state, without preventing the determination of tetravalent selenium and tellurium. Thiourea also eliminates the interference from a number of metals in the determination of arsenic, antimony and bismuth, but it is not effective for selenium and tellurium.
Spectrophotometry Volatile generation Volatile generation

"Sensitive Determination Of Selenium By Inductively Coupled Plasma Mass Spectrometry With Flow Injection And Hydride Generation In The Presence Of Organic Solvents"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 10 Pages 865-870
Riansares Muñoz Olivas, C. R. Quétel and O. F. X. Donard

Abstract: Two sample introduction methods, viz., pneumatic nebulization and hydride generation via a flow injection system were used to study the optimum conditions for Se determination. The effect of organic solvents in polyatomic interferences (40Ar, 37Cl, 40Ar, 38Ar and 40Ar2H2) suppression and signal enhancement were investigated. The organic solvents studied were: methanol, ethanol, propanol, acetone and acetonitrile. A SCIEX Perkin Elmer 5000 spectrometer was used. The pneumatic nebulization flow rate ranged from 0.95-1.05 L/min and the Ar flow rate for hydride generation was similar (1.05-1.1 L/min); other operating conditions are tabulated. Under optimum conditions (NaBH4 = 0.2%, pH = 1, methanol load = 6%) for flow injection hydride-generation ICP-MS a detection limit of 1 pg of Se was obtained using a 200 µL sample. The average RSD was 2%. The method was applied to estuarine water and Se levels ranged from 5 to 70-80 ng/L. Validation was via an EC certification campaign.
Estuarine Mass spectrometry Volatile generation Optimization Organic solvent Method comparison Interferences Signal enhancement Volatile generation

"Optimization Of Flow Injection Hydride Generation Inductively Coupled Plasma Mass Spectrometry For The Determination Of Selenium In Water And Serum Samples"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 10 Pages 871-874
M. Angeles Quijano, Ana Maria Gutiérrez, M. Concepcion Pérez Conde and Carmen Cámara

Abstract: Water was acidified with concentrated HCl (3 mL per 5 mL sample), boiled to 100°C for 10 min and after cooling diluted to 10 mL with water. Serum (1 ml) was diluted to 50 mL with water and treated similarly to the water samples (loc. cit.); Si was used as anti-foaming agent. The effects of NaBH4 concentration, HCl concentration, flow rates, sample volume, forward power and carrier gas flow rates were studied and optimized. Optimum conditions were: 0.5% (m/v) NaBH4; 0.6 M HCl; HCl and NaBH4 flow rates of 3.5 and 1.7 ml/min, respectively; sample volume = 100 µL with 30 cm coil lengths, an r.f. power of 1350 W; and an Ar flow-rate = 1.01 ml/min. The interference from 31 elements was investigated; serious interference was caused by some transition elements. The calibration graph was linear up to 30 µg/l and the detection limit was 35 ng/l of Se which is 100 times better than that possible with traditional pneumatic nebulization. RSD (n not stated) were 5%. Recoveries were 92-104%.
Blood Serum Environmental Mass spectrometry Volatile generation Optimization Speciation Interferences Volatile generation

"Thermally Stabilized Iridium On An Integrated, Carbide-coated Platform As A Permanent Modifier For Hydride-forming Elements In Electrothermal Atomic Absorption Spectrometry. 3. Effect Of L-cysteine"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 10 Pages 989-995
Dimiter L. Tsalev, Alessandro D'Ulivo, Leonardo Lampugnani, Marco di Marco and Roberto Zamboni

Abstract: The concentrations of cysteine (0.2-2%), NaBH4 (0.05-0.4%) and HCl (0.01-0.15M) for the generation of hydrides to be trapped in an ET atomizer coated with Ir/Zr (cf. Ibid., 1995, 10, 1003) in an automated flow injection hydride-generation system (Ibid., 1996, 11, 979) were optimized by a full 33 factorial design. Analytically useful conclusions are drawn, e.g., the presence of cysteine renders the pH adjustment of sample digests more critical.
Sample preparation Spectrophotometry Optimization Volatile generation Factorial design Volatile generation

"Thermally Stabilized Iridium On An Integrated, Carbide-coated Platform As A Permanent Modifier For Hydride-forming Elements In Electrothermal Atomic Absorption Spectrometry. 2. Hydride Generation And Collection, And Behaviour Of Some Organoelement Species"
J. Anal. At. Spectrom. 1996 Volume 11, Issue 10 Pages 979-988
Dimiter L. Tsalev, Alessandro D'Ulivo, Leonardo Lampugnani, Marco di Marco and Roberto Zamboni

Abstract: The Ir/W- and Ir/Zr-treated platforms (i.e., a permanent Ir modifier stabilized on a W- or Zr-treated platform) proposed previously (Ibid., 1995, 10, 1003) have been evaluated in direct ETAAS and in an automated flow injection hydride-generation ETAAS system in respect of the effects of the hydride-generation parameters, the purge-gas flow rate and the trapping temperature, and the long-term stability of the measurements, the behavior of some organometal species, and their applicability to real analyzes. It is concluded, inter alia, that the Ir/Zr-treated platforms are the more suitable for trapping the hydrides of As, Bi, Sb, Se, Sn and Te in an automated system, but that the Ir/W-treated platforms are the more suitable in direct ETAAS.
Spectrophotometry Optimization Volatile generation Volatile generation

"Analysis Of Geological Materials For Bismuth, Antimony, Selenium And Tellurium By Continuous-flow Hydride-generation Inductively Coupled Plasma Mass Spectrometry. 2. Methodology And Results"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 1 Pages 103-106
GWENDY E. M. HALL and JEAN-CLAUDE PELCHAT

Abstract: The apparatus and procedure for removal of mutual interference were as described in Part 1 (Ibid., 1997, 12, 97). Sample digestion with aqua regia gave complete recovery of Bi, but some matrices required digestion with HF/HClO4/HNO3/HCl to obtain full recoveries of Te, Se and Sb. The analytes were separated from some potentially interfering elements (e.g., Co, Cu and Ni) by coprecipitation on lanthanum hydroxide. Results are presented for 18 of the Chinese GSD and GSR stream sediment and rock standard reference materials. RSD were in the range 3-8% and the detection limits were 1 µg/kg for Bi and Te and 6 µg/kg for Sb and Se.
Geological Environmental Sample preparation Mass spectrometry Detection limit Coprecipitation Interferences Reference material

"Determination Of Selenium In Geochemical Samples By Flow Injection Hydride-generation Inductively Coupled Plasma Atomic-emission Spectrometry Following Online Removal Of Iron Interference By Anion Exchange"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 4 Pages 487-490
L. D. MARTINEZ, E. SAIDMAN, E. MARCHEVSKY and R. OLSINA

Abstract: A 0.5 g sample was acid-digested by the method of Subramanian (Fresenius' Z. Anal. Chem., 1981, 305, 382), the product was heated with HCl at 90°C for 1 h to reduce Se(VI) to Se(IV), and the resulting solution was diluted to 25 mL. This solution was pumped into the manifold illustrated for retention of the Fe on a microcolumn of Dowex 1-X8, and then passed to an injection valve for injection of a 0.7 mL portion into a carrier stream of water that subsequently merged with streams of 6 M HCl and 0.6% NaBH4 solution. The hydride was then generated in a reaction coil and passed via a gas-liquid separator to the plasma in a stream of Ar. The calibration graph was linear up to 30 ng/ml of Se with a detection limit of 0.3 ng/ml. The RSD (n = 10) was 2% at 20 ng/ml of Se. The results for geochemical standard reference materials agreed well with the certified values.
Geological Ion exchange Sample preparation Spectrophotometry Sample preparation Solid phase extraction Reference material Volatile generation Phase separator Interferences Dowex Volatile generation

"Inductively Coupled Plasma-mass Spectrometry For Direct Multielement Analysis Of Diluted Human Blood And Serum"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 9 Pages 1005-1009
EBBA BARANY, INGVAR A. BERGDAHL, ANDREJS SCHÜTZ, STAFFAN SKERFVING and AGNETA OSKARSSON

Abstract: A method for the inductively coupled plasma mass spectrometry (ICP-MS) multi-element analysis of diluted human blood and serum was used for the following elements: Co, Ni, Cu, Zn, Ga, Se, Rb, Mo, Ph, Pd, Cd, Sn, Sb, W, Pt, Hg, Tl and Pb. Sample pretreatment was a simple dilution (ten times for blood and five times for serum) with a solution containing 5 g L-1 of 25% ammonia, 0.5 g L-1 Triton X-100, and 0.5 g L-1 EDTA in Millipore water. In and Sc were used as internal standards. For sample introduction a flow injection type technique (based on time instead of volume) was used. The determinations mere carried out first in a peak-jumping mode for selected masses, and then in a scanning mode. Each determination of a preparation took 75 s. The results for reference samples agreed with recommended or certified values for Co, Cu, Zn, Rb, Cd, Tl and Pb in blood, and for Rb, Mo and Cd in serum. For Ni and Hg in blood, and Cu and Zn in serum, the results agreed with one of two reference samples. The detection limits for all these elements (except for Tl) were sufficient for analysis of samples from the general population. On the other hand, the results for Se in blood, and for Co, Ni, Se, Sn and Hg in serum did not agree with recommended or certified values. No reference samples are available for Ga, Mo, Ph, Pd, Sn, Sb, W, or Pt in blood, or for Ga, Ph, Pd, W, Pt, or Pb in serum. Generally, the limits of detection for the elements in the latter group (below 0.15 µg l-1) are close to or above the levels present in the general population.
Whole Human Serum Human Mass spectrometry Multielement Interferences Timed injection Reference material Triton X Surfactant

"Determination Of Selenium In Solid Samples By Continuous Subcritical Water Extraction, Flow Injection Derivatization And Atomic Fluorescence Detection"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 8 Pages 787-791
C. M. Rico Varadé and M. D. Luque de Castro

Abstract: A method for the determination of selenium in solid samples is proposed. The method involves two main steps: (a) continuous leaching of the analyte by subcritical water (250°C, 200 bar, 0.7 mL min-1), which is complete in 15 min and (b) continuous derivatization (hydride formation) and detection by atomic fluorescence. The design of the derivatization manifold, based on flow injection, enables speciation anal. of inorganic selenium (as Se(IV)/Se(VI)) and organo-selenium compounds by appropriate selection of the reagent streams. Both conversions of organic into inorganic Se by oxidation and reduction of the Se(VI) formed as well as that of Se(VI) initially present in the samples to Se(IV) is accelerated by irradiation with focused microwaves using 1 m reactors and a flow-rate of 4.4 mL min-1. The linear range of the calibration curves is between 10^-50,000 ng mL-1 with relative standard deviation values <4.5%. The method was applied successfully to sludge samples from an interlaboratory study. The drastic conditions of extraction convert organic Se into inorganic, so the method does not enable inorganic-Se/organic-Se speciation in solid samples.
Waste Fluorescence Sample preparation Volatile generation Speciation Microwave Heated reaction

"Direct Liquid Sample Introduction For Flow Injection Analysis And Liquid Chromatography With Inductively Coupled Argon Plasma Spectrometric Detection"
Anal. Chem. 1984 Volume 56, Issue 2 Pages 289-292
Kimberly E. Lawrence, Gary W. Rice, and Velmer A. Fassel

Abstract: A micro-concentric nebulizer is described, use of which enables the solution from a flow injection analysis system, or the eluent from a HPLC column, to be analyzed directly by ICP-AES Detection limits by flow injection analysis - ICP ranged from 0.32 ppb for Mg to 140 ppb for Se, these being poorer, by factors ranging from 1.1 to 4.6, than those obtained by continuous nebulization with a cross-flow nebulizer. When Cr and As species were determined by HPLC - ICP, detection limits (ppm) were Cr(III) 0.44, Cr(VI) 0.43, As(V) 1.8 and As, as methanearsonic acid, 0.64. The very high linear velocity of the nebulizing gas and the excessive solvent loading were responsible for the poorer detection limits, and improvements to the nebulizer design are being investigated.
HPLC Spectrophotometry Apparatus Multielement Sample valve manipulation

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

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

"Semiautomated Method For The Determination Of Selenium In Geological Materials Using A Flow Injection Analysis Technique"
Anal. Chem. 1985 Volume 57, Issue 7 Pages 1482-1485
Chris C. Y. Chan

Abstract: A non-segmented stream is used instead of an air-segmented stream in a continuous-flow system in series with hydride generation and AAS A flow injection module is used for insertion of the sample segment into the stream, and, as air bubbles are not required for mixing and segmenting the solution, narrow tubing can be used throughout. This allows more rapid transport of the sample, the sample zone is better defined and not diluted by the carrier solution, the volumes of sample segments are very reproducible and the sample and reagent solution can be well mixed within a narrow stream, so that the signal response is more rapid and precise with improved peak shape and height. Results from the analysis of 40 reference samples gave coefficient of variation of 15% with a mean of 2.85% (n = 3 to 10). The limit of determination was 5 ppm of Se.
Geological Geological Spectrophotometry Reference material Peak shape

"Hydride-generation Atomic Absorption Spectrometry Coupled With Flow Injection Analysis"
Anal. Chem. 1985 Volume 57, Issue 7 Pages 1382-1385
Manabu Yamamoto, Makoto Yasuda, and Yuroku Yamamoto

Abstract: Flow injection analysis was combined with the gas-segmentation method described by Skeggs (Am. J. Clin. Pathol., 1957, 28, 311) for the determination of As, Sb, Bi, Se and Te. On synthetic samples the coefficient of variation were between 0.5 and 0.8% (n = 10) with detection limits between 0.04 and 0.3 ng. The results on NBS steel, wheat and rice flour, orchard leaves and coal fly ash were close to certified values and the differential determination of As and Sb in thermal water was possible. Tolerance limits for diverse ions are listed.
NIST 1633 NIST 1567 NIST 1568 NIST 1571 Rice Flour Wheat Flour Alloy Thermal Plant Industrial Spectrophotometry Reference material Segmented flow

"Inductively Coupled Plasma Mass Spectrometric Detection For Multielement Flow Injection Analysis And Elemental Speciation By Reversed-phase Liquid Chromatography"
Anal. Chem. 1986 Volume 58, Issue 12 Pages 2541-2548
Joseph J. Thompson and R. S. Houk

Abstract: The effluent from the HPLC column was converted into an aerosol by ultrasonic nebulization with desolvation for analysis on a Sciex ELAN model 250 ICP-MS instrument. Mobile phases used were methanolic solution of Na pentanesulfonate and tetrabutylammonium phosphate and the column (25 cm x 4.6 mm) contained Econosphere C18. Flow injection analysis coupled with ICP-MS was used to measure instrument response to a transient signal. Detection limits by flow injection analysis and by HPLC are reported for several elements. The separation and selective detection of As and Se species were shown; detection limits were ~0.1 ng (as the element) for all six species. Up to 15 elements could be determined in a single injection with multiple-ion monitoring. Isotope ratios measured on eluates containing Cd and Pb showed good accuracy, indicating that HPLC coupled with ICP-MS should allow speciation studies with stable tracer isotopes.
HPLC Mass spectrometry Spectrophotometry Speciation

"Hydride-generator System For A 1-kW Inductively Coupled Plasma"
Anal. Chem. 1989 Volume 61, Issue 3 Pages 285-288
J. David Hwang, Gary D. Guenther, and John P. Diomiguardi

Abstract: A continuous-flow hydride-generation system is described for use with a 1-kW ICP. Acidified sample solution and NaBH4 solution are pumped continuously by a multi-channel peristaltic pump into the hydride generator, wherein the sample solution flows down the outside of the NaBH4 tube and mixes and reacts with the NaBH4 solution as it emerges, thereby overcoming the dilution effects that occur in conventional hydride-generation systems. Also, smaller amounts of gaseous by-products are produced, thereby yielding a more stable plasma. Detection limits were 0.1, 1.4, 0.6, 0.3 and 1 ng mL-1 for As, Bi, Sb, Se and Sn, respectively, which are 30 to 700 times better than obtained with pneumatic nebulization.
Spectrophotometry Volatile generation Volatile generation

"Development Of Catalytic Photometric Flow Injection Methods For The Determination Of Selenium"
Anal. Chem. 1991 Volume 63, Issue 7 Pages 692-699
aul M. Shiundu and Adrian P. Wade

Abstract: A carrier stream of 0.1 M phenylhydrazine hydrochloride was merged with a flow of 0.5 M KClO3 to give a total flow rate of 1.0 mL min-1. The mixture was passed via an injection valve, where the Se(IV) sample was added to, a 50-cm reaction coil. Two other channels of 1.2 M HCl (0.5 mL min-1) and 0.02 M chromotropic acid (0 to 1 mL min-1) were merged before all the streams were passed through a 300-cm reaction coil at 60°C. The absorption of the red complex was measured at 360 nm using a diode-array spectrophotometer. The reaction followed pseudo-first-order kinetics. Interference studies showed that most metal ions could be tolerated at 100 ppm and others could be masked with EDTA. The performance of the optimized conventional flow injection manifold was compared with that of stopped-flow and flow-reversal configurations. The conventional manifold had a sample throughput rate of >60 h-1, a detection limit of 0.52 ppm of Se(IV) and a rectilinear range of 0 to 50 ppm. When the sample plug was stopped for 30 s, the sensitivity was increased by a factor of 2.5 while maintaining a throughput of 45 h-1. At this rate, the flow-reversal method gave improved sensitivity and a detection limit of 0.15 ppm. A reverse trend of conventional >stopped-flow >flow reversal was observed for the rectilinear dynamic range.
Spectrophotometry Catalysis EDTA Heated reaction Kinetic Interferences Optimization Reverse Stopped-flow

"Determination Of Selenium By Inductively Coupled Plasma Mass Spectrometry Utilizing A New Hydride Generation Sample Introduction System"
Anal. Chem. 1992 Volume 64, Issue 7 Pages 724-729
Wayne T. Buckley, James J. Budac, David V. Godfrey, and Karen M. Koenig

Abstract: An ICP-MS method with a continuous-flow hydride generator was described for the determination of Se in biological materials of animal and plant origin. The design of the hydride generator was important in minimizing interference from HCl and in maximizing sensitivity. Two digestion - ashing sample preparation procedures were described which have either 3.8 or 7.2 M-HCl in the final solution Interference from Cu was eliminated by adding 0.2 M NaI to the NaBH4 solution (3.8 M method) or by maintaining a high concentration. of HCl in the sample solution (7.2 M method). The advantages and disadvantages of the two methods were discussed. Cross-contamination from sample to sample was negligible due to elimination of the air bubble normally entrained between them. A detection limit of 6.4 pg of Se was obtained under optimum conditions, whereas a limit of 1.3 ng was found in the routine isotope dilution analysis of 1 g samples of plant material. The determination of Se in a variety of biological reference materials was reported.
Biological Plant Sample preparation Sample preparation Mass spectrometry Interferences Reference material Optimization Phase separator

"Metal Speciation By Supercritical-fluid Extraction With Online Detection By Atomic Absorption Spectrometry"
Anal. Chem. 1994 Volume 66, Issue 22 Pages 3900-3907
Jin Wang and William D. Marshall

Abstract: A silica flame-in-tube interface is described for the AAS detection of As, Cd, Cu, Mn, Pb, Se or Zn in the eluate from a SFE apparatus. It consisted of a heated optical tube placed within the optical beam of the spectrometer, a flame tube fitted with H2 and O2 gas entry ports and a sample introduction tube. The analyte metal in an aqueous medium was complexed in situ with tetrabutylammonium dibutyldithiocarbamate and the derivative was mobilized into supercritical CO2. The superheated extractor eluate was nebulized into the upper region of a diffuse flame in the interface flame tube and introduced into the optical tube for analysis. The optimal flame conditions were slightly reducing for aqueous and CO2 mobile phases but slightly oxidizing for a methanolic mobile phase. The detection limits of the metals were in the sub ng to low pg range when a standard was flow-injected into the mobile phase. The recoveries of 5 or 10 µg/ml of Cu, Mn and Pb were 92-94.4% with RSD of 0.1%; the RSD for the cumulative area under the AAS response curve was appreciably more variable. The differences in the rates of mobilization of analyte metal from different matrices was studied using fresh and freeze-dried bovine liver.
Liver Sample preparation Spectrophotometry Speciation Solvent extraction

"Determination Of Arsenic, Antimony, Bismuth, Selenium And Tin In Biological And Environmental Samples By Continuous-flow Hydride-generation ICP-AES Without Gas-liquid Separator"
Fresenius J. Anal. Chem. 1991 Volume 340, Issue 1 Pages 41-47
P. Schramel and Li-Qiang Xu

Abstract: Arsenic, Sb, Bi, Se and Sn were simultaneously determined in samples by ICP-AES with use of the cited hydride-generation system (diagram given) at 1.5 kW. Samples were digested (i) under pressure with 70% HNO3 in a closed vessel at 170°C for 10 h and (ii) with HNO3 - ClHO4 - H2SO4 (details given). Sample solution in 30% HCl - 20% HNO3 were mixed with a reductant solution consisting of 3% NaBH4 and 2% KI prior to nebulization in the ICP spectrometer and determination by AES. Interferences caused by Cu and Ni ions were eliminated with use of the reductant. In general results were in good agreement with certified values; detection limits were at the ng level.
Biological Environmental Sample preparation Spectrophotometry Interferences Nebulizer Reference material

"Heterogeneous Hydride Generation In A Packed Membrane Cell"
Fresenius J. Anal. Chem. 1991 Volume 341, Issue 9 Pages 532-536
Solomon Tesfalidet and Knut Irgum

Abstract: Volatilization of arsenic, selenium and antimony for sample introduction in atomic absorption spectrometry has been performed by pumping an acidic sample through an anion exchanger in the tetrahydroborate (III) form packed as a bed in the liquid channel of a gas-liquid separation membrane cell. The hydrides generated in the heterogeneous reaction between bound tetrahydroborate (III) ions and the analytes are rapidly transferred with the aid of the concomitantly generated hydrogen gas through the gas-permeable membrane into the gas phase and swept to the spectrometer by an additional hydrogen gas flow. This instant transfer of the hydrides to the gas phase kinetically discriminates the reaction of the hydride with metal borides and metal colloids, whose formation by reaction with tetra-hydroborate (III) is slower than the hydride reaction. The susceptibility to interference by transition metal ions is thus markedly reduced, as compared with both batch hydride generation methods and a previously presented heterogeneous reaction scheme. The detection limits for arsenic, selenium, and antimony were 1.2, 3.7, and 10 g/l, respectively. The calibration graphs were linear from the detection limit up to 125 g/l for arsenic, 150 g/l for selenium, and 250 g/l for antimony. The relative standard deviations at concentration levels of 10 and 100 g/l were 1.8 and 0.7% for arsenic and 2.3 and 1.2% for selenium. Corresponding figures for 50 and 100 g/l antimony were 2.5 and 1.6%.
Spectrophotometry Volatile generation Interferences Membrane Volatile generation

"Microbiological Assay For Chemical Species Of Selenium In Foods Utilizing Escherichia Coli Formate Dehydrogenase"
Fresenius J. Anal. Chem. 1993 Volume 345, Issue 2-4 Pages 243-246
Elizabeth Tschursin and Wayne R. Wolf

Abstract: The assay method depends on the fact that the formate dehydrogenases present in E. coli depend on the presence of Se for their synthesis. Samples were mixed with a minimal medium and incubated at 37°C for 22 or 32 h, depending on the cell strain, and the CO2 evolved was determined with an IR analyzer.. Dose response curves for selenite, selenocystine and selenomethionine showed sensitivities down to the pmol mg-1 range. A wheat gluten reference sample (NIST 8418) was hydrolyzed with 6 M HCl and was fractionated on an AG 50 W-X8 column; the hydrolysate was eluted with Li+ buffers of pH 2.2, 7.5 and 13. The pH 7.5 fraction was analyzed for amino-acids on a cation-exchange column, with post-column derivatization with o-phthalaldehyde and fluorescence detection. This fraction was also tested in the bioassay. Analysis for selenomethionine (I; the main Se compound in gluten) was complicated by a matrix effect by the much more abundant methionine and possible interference by seleno-cystine, which is more sensitive in the assay. These problems must be overcome before I can be determined in foods and reference materials.
Food Fluorescence Post-column derivatization Reference material Interferences

"Study Of Some Interfering Processes In The Arsenic, Antimony And Selenium Determination By Hydride-generation Atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1993 Volume 346, Issue 6-9 Pages 622-626
Maciej Walcerz, Ewa Bulska and Adam Hulanicki

Abstract: A twin-channel continuous-flow apparatus was used to determine at what stage interference was occurring in the cited analysis. Each channel had its own gas-liquid separator and the two gas phases, with Ar (300 ml/min) as carrier gas, were united just before the furnace. In the single-channel mode, one channel carried the analyte with increasing concentration. of interferent; the second channel contained a blank solution of 2 M HCl. In the twin-channel mode, one channel contained the analyte and the other the interferent. If the results in the two modes were similar, the interference occurred in the gas phase, while differences indicated some interference in the liquid phase. Studies were carried out using analyte concentration. of 50 µg/l and interferent cocncn. of 0.2-50 mg/l. The reducing solution was 0.5% NaBH4 solution in 0.1 M NaOH. The effects of As, Bi, Pb, Sb, Se, Sn and Te (as interferents) on As, Sb and Se (as analytes) are reported. Spectral interference by As and Sb in the 190-235 nm region was caused by molecular bands.
Spectrophotometry Interferences

"Removal Of Iron Interference In The Determination Of Selenium In Geological Samples By Continuous-flow Hydride Generation ICP-AES"
Fresenius J. Anal. Chem. 1996 Volume 354, Issue 1 Pages 126-127
L. D. Martinez, M. Baucells, E. Pelfort, M. Roura, R. Olsina

Abstract: Samples (0.5 g) were digested with 6 mL HCl and 2 mL HNO3, the mixture was cooled, 5 mL HClO4 and 10 mL HF were added and the mixture was left overnight. The solution was evaporated until fumes of HClO4 ceased. This step was repeated until complete solution was obtained, the liquid was treated with 4 mL water and 2 mL HNO3 and diluted to 20 mL with water. The pH was adjusted to 0.5-2 with NH3, 10 mL 2% aqueous ammonium pyrrolidine-1-yl-dithioformate was added and the Fe(III) complex formed was extracted into 10 mL CHCl3. This step was repeated until the extracts were colorless. The aqueous phase was heated with 1 mL HNO3, the Se(VI) was reduced to Se(IV) by heating in 6 M HCl at 60°C for 30 min and the solution was diluted to a suitable volume. In the flow system, 0.6% NaBH4 in 0.5% NaOH was pumped at 1 ml/min, 6 M HCl at 1 ml/min and the sample solution at 6 ml/min. After mixing in a reaction coil, the solution was transferred to a gas-liquid separator and the gas phase was transported into the ICP-AES with Ar (90 ml/min) for measurement. The detection limit was 0.15 ng/ml of Se. Recovery of 50 and 300 ng of Se averaged 96 ± 2.8% and 99 ± 1.1% respectively. Satisfactory results were obtained on three certified samples.
Geological Spectrophotometry Reference material Interferences

"A Flow Injection Flame-atomic Absorption Spectrometry System For The Determination Of The Real Stoichiometry Of Small CuInSe2 Semiconductor Crystals"
Fresenius J. Anal. Chem. 1996 Volume 354, Issue 2 Pages 184-187
A. Matousek Abel de la Cruz, J. L. Burguera, M. Burguera, S. Wasim, C. Rivas

Abstract: A method for the rapid determination of the real stoichiometry of small CuInSe, semiconductor crystals is presented. The powdered crystal samples have been weighed and acid dissolved in a closed dissolution system connected to a FI manifold for flame atomic absorption spectrometry (AAS) determination. The accuracy has been assessed by comparing the results obtained with those by conventional AAS, and by analyzing CuInSe2 polycrystals of known stoichiometry. The results obtained with the proposed method are in a good agreement with the expected values. The method alloys the dissolution of the crystals without any detectable loss of selenium and has been applied to the analysis of small samples of CuInSe2 monocrystals as a method for routine monitoring during the development of synthesis methods and in homogeneity studies of the crystal ingots. Finely ground CuInSe2 (3 mg; I) were dissolved in 1 mL 65% HNO3 and the solution was diluted to 10 mL with water in a closed dissolution system connected to a flow injection manifold (illustrated). Portions (120 µL) were diluted (1:10) with water (5 ml/min) in a dispersion coil (48.5 cm x 1 cm i.d.) and transferred to an AAS operated with air-acetylene burner gas and a nebulizer aspiration rate of 6 ml/min. Cu, In and Se were determined with lamp currents of 4 mA at 324.8 nm, 5 mA at 303.9 nm and 10 mA at 196 nm and slit widths of 0.7, 0.7 and 2 nm, respectively. Calibration graphs were linear from 5-80, 25-400 and 20-400 mg/l, respectively, for Cu, In and Se. The method was compared with the conventional open dissolution and direct batch aspiration procedure. RSD were 1.8-2.9 and 2.2-3.6%, respectively, for Cu and In were similar for both procedures but the RSD for Se were lower, 2.9-3.2% vs. 4.5-5%.
Industrial Spectrophotometry Method comparison Process monitoring Stoichiometry

"Selenium Determination By Hydride-generation ICP-AES: Elimination Of Iron Interferences By Means Of An Ion-exchange Resin In A Continuous-flow System"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 7 Pages 850-852
L. D. Martinez, M. Baucells, E. Pelfort, M. Roura, R. Olsina

Abstract: Sample solution prepared from geological materials (details given) was subjected to online SPE on a Dowex 50W-X8 cation-exchange column (5-10 cm x 3 mm i.d.) at 2 ml/min to remove Fe. A portion (500 µL) of the extract was injected into a water stream (6 ml/min), which merged with a stream (1 ml/min) of 6N-HCl and a stream (1 ml/min) of 0.6% NaBH4. The flow passed through a reaction coil (dimensions not given) and into a gas-liquid separator. Volatile hydrides were carried in Ar (90 ml/min) into a plasma torch for ICP-AES determination of Se (operating conditions given). The column eliminated interference from 2.5 mg/ml Fe in the determination of 20 ng/ml Se. The detection limit ws 0.4 ng/ml Se, recoveries were 98-99.5% and the RSD (n = 10) was 2%. Calibration details are not given. The method was applied to geological CRM. The results agreed with the certified values.
Geological Ion exchange Sample preparation Spectrophotometry Sample preparation Solid phase extraction Reference material Volatile generation Phase separator Interferences Dowex Resin Volatile generation

"Validation Of Three Atomic Absorption-spectrometric Methods For The Determination Of Selenium - A Comparative Evaluation Of Performance Characteristics"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 8 Pages 1024-1028
R. Allabashi, J. Rendl, M. Grasserbauer

Abstract: The methods used were: ET AAS (method A), flow injection hydride generation AAS (method B) and continuous-flow hydride generation AAS with ET atomization (method C). The analyzes were performed on a Perkin Elmer 4100-ZL instrument with an electrodeless discharge lamp as Se radiation source; detection was at 196 nm for all three methods. In method A, the sample (20 µL) and 5 µL modifier solution [palladium(II) nitrate/magnesium(II) nitrate (5:3)] were simultaneously injected then ashed and atomized according to the temperature program described previously (Allabashi, R, Thesis, 1996). For method B, 500 µL sample was channelled into a carrier flow of HCl (10 ml/min) and brought together with NaBH4 (5 ml/min); the gaseous products were carried by Ar gas for analysis. In method C, the acidified sample was continuously transported at 6 ml/min into the reaction cell where it was mixed with NaBH4 (3 ml/min). The continuously formed hydride was heated to 400°C for analysis as described previously (Int. J. Environ. Anal. Chem., 1996, submitted) and temperature programming as for method A was used. Each method performed well but has a typical optimal application along with specific advantages (details given).
Spectrophotometry Spectrophotometry Volatile generation Method comparison Optimization Volatile generation

"Determination Of Selenium In Soil By Hydride Generation AAS"
Fresenius J. Anal. Chem. 1998 Volume 360, Issue 2 Pages 225-229
V. Kos A, Marjan Veber A, Vida Hudnik

Abstract: Hydride generation AAS was applied for the determination of total selenium in soil. The influence of various anions and cations present in the sample solution on the generation of selenium hydride was investigated. Special attention was paid to the wet oxidation procedure for the sample dissolution. The proposed procedure involves microwave sample preparation by using a mixture of H2O2/HNO3/H2SO4. The accuracy of the procedure was checked by the analysis of the standard reference material Buffalo River Sediment (SRM-2704, NIST). Satisfactory agreement of the results obtained with the values reported was achieved. The detection limit of the procedure was 25 ng Se/g of soil. The relative standard deviation of the measurements varied from 5.5% for SRM-2704 up to 10% for the real soil samples.
Environmental Spectrophotometry Volatile generation

"Selenium Determination Using Ethylation And Online Trapping/detection By Graphite Furnace Atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1998 Volume 360, Issue 6 Pages 723-725
R. Allabashi A, J. Rendl A, M. Grasserbauer

Abstract: An on-line system for the continuous ethylation of selenium (IV) in combination with trapping and detection of the produced diethylselenide in the coated AAS graphite furnace was developed. Due to the slow kinetics of the ethylation the volume of the reaction coil and the reaction time had to be increased to 5.5 mL and 80 s, respectively. The sensitivity of the method was comparable with that of the hydride generation in the same system and the relative standard deviation was 6-10%. The determination of Se(IV) in real samples after the most widely used digestion with nitric acid could not be accomplished, because of the drastic signal depression caused by this acid.
Spectrophotometry

"Determination Of Arsenic, Selenium And Mercury In An Estuarine Sediment Standard Reference Material Using Flow Injection And Atomic Absorption Spectrometry"
Microchim. Acta 1995 Volume 118, Issue 3-4 Pages 163-175
Rajananda Saraswati, Thomas W. Vetter and Robert L. Watters Jr.

Abstract: Sediment (0.3 g) was digested with 5 mL each of concentrated H2SO4 and HNO3 and 2 mL concentrated HCl in a microwave oven (program tabulated), excess HNO3 was removed and the samples were diluted to 200 mL with 2% HCl. For Hg determination, a similar method was followed using 10 mL concentrated HNO3 (program tabulated) and the digests were mixed with 0.75 mL 1% K2Cr2O7 and diluted to 100 mL with 1% H2SO4. Reduction of As and Se was performed as described previously (Analyst, 1995, 120, 95) prior to analysis by flow injection AAS at 193.7 and 196 nm, respectively (loc. cit.; operating conditions tabulated). To determine Hg, samples (500 µL) were injected into a carrier stream (10 ml/min) of 3% HCl, mixed with 1% SnCl2 (6 ml/min) in an 11 cm reaction coil and the Hg vapor was separated and carried in Ar (80 ml/min) to the absorption cell for AAS at 253.7 nm. The calibration graphs were linear for up to 20, 25 and 6 ng/ml As, Se and Hg, respectively, and the corresponding detection limits were 0.15, 0.17 and 0.15 ng/ml. The RSD are tabulated. The results agreed with those obtained using reflux column digestion; the sample preparation time was 1-2 h.
Estuarine Sample preparation Spectrophotometry Spectrophotometry Reference material Method comparison

"The Use Of Reference Materials In The Fossil Fuels Quality Control"
Microchim. Acta 1996 Volume 123, Issue 1-4 Pages 217-230
Maurizio Bettinelli, Sandro Spezia, Umberto Baroni and Gabriele Bizzarri

Abstract: Quality control procedures used for the determination of trace elements in fuel oil and coal are described. Two standard reference materials (NIST 1632a and 1632b) were used to evaluate the accuracy in the determination of As, Hg and Se in coal by flow injection (FI) hydride-generation (HG) AAS and FI HG ICP-MS after microwave solubilization (Anal. Chim. Acta, 1989, 225, 159). RSD over 2 years were 10% for As, 8.11% for Se and 15% for Hg. The use of real fuel oil samples to compare results obtained for the determination of Ni and V by NAA, ICP-MS, ETAAS and ICP-AES in 54 laboratories is discussed. Similarly, the use of real samples to detect significant bias in the determination of As, Hg and Se in coal using various techniques (NAA, FI HG AAS, FI HG ICP-MS, ETAAS) is discussed.
NIST 1632 Oil Sample preparation Spectrophotometry Spectrophotometry Mass spectrometry Mass spectrometry Reference material Method comparison

"Determination Of Arsenic And Selenium By Hydride Generation Atomic Absorption Spectrometry Using A Gas-liquid Separator And A Dehydration Trap"
Microchem. J. 1996 Volume 53, Issue 1 Pages 18-25
Hisatake Narasaki and Jun-Yan Cao

Abstract: Biological material (0.25 g) was allowed to stand overnight in 3 mL concentrated HNO3, 0.5 mL concentrated H2SO4 and 1 mL 60% HClO4 were added and the mixture was digested under low heat until the fumes of HClO4 subsided. The digests, including siliceous residues, were transferred to a Pt dish with water and evaporated to 2 mL. The residues were dissolved with 5 mL 46% HF, 1 mL 9 M H2SO4 was added and the solution was concentrated to 2 mL. The pH was adjusted to 3.5 with 1 M NH3 and applied to a SPE column (35 cm x 10 mm i.d.) packed with 10 cm Chelex 100 chelating ion-exchange resin and the column was washed with 2 x 10 mL water. For the analysis of As; the column effluents were diluted to 100 mL with water and a 10 mL portion was mixed with 5 mL 6 M HCl. Portions of both acid solutions were introduced into the flow injection hydride generation system (schematic shown) and mixed with a stream of 2% sodium tetrahydroborate(III) solution in a Pyrex mixing coil (16 cm x 2 mm i.d.). The hydride generated was collected in a gas-liquid separator, dehydrated in a dehydration trap and swept into an electrically heated furnace with a carrier stream of N2 (2.5 l/min) by manipulating electromagnetic relays and timers (operating details given). The atomized As and Se species were detected at 193.7 and 196 nm, respectively, by AAS. The detection limits were 0.6 and 1 ng/ml, respectively. Tolerance levels to 10 foreign ions are listed. The method was applied to the analysis of five NIST Standard Reference materials (listed). Results agreed well with certified values.
Hepatopancreas Rice Flour Wheat Flour Oyster Plant NIST 1566 NIST 1567 NIST 1568 NIST 1571 NRCC TORT-1 Spectrophotometry Reference material Chelex

"Investigation Of Stable Coatings For In Situ Trapping Of Selenium And Tellurium In Flow Injection Hydride-generation And Graphite-furnace Atomic Absorption Spectrometry For Automated Determination"
Microchem. J. 1997 Volume 56, Issue 2 Pages 247-258
Y. -p. Liao and H. O. Haug

Abstract: The use of highly stable trapping reagents instead of a Pd modifier for Se and Te determinations was investigated. Best results were achieved with Ir- and Ir/Mg-coated graphite tubes at 550-800°C. With Te some 'carryover effect' was observed at temperatures >600°C. Measurements were performed with use of a spectrAA-800 Zeeman atomic absorption spectrometer at 196 and 214.3 nm for Se and Te, respectively, (other operating parameters are tabulated). The detection limits were ~0.011 and 0.007 ng for Se and Te, respectively, on Ir-coated tubes using a 1 mL sample loop. The method was applied to the determination of Se and Te in low-alloy steel certified reference materials. Flow injection hydride generation and in situ concentration of Se and Te hydrides in graphite furnace atomic absorption spectrometry (AAS) can be automated using a highly stable trapping reagent replacing the Pd modifier. In a systematic study, carbide-forming elements (Zr, Nb, Ta, W) and noble metals (Ir, Ir/Mg, Pd/Ir) were investigated as stable adsorbers which require only a single application. Effective trapping of the Se and Te hydrides is achieved on Ir- and Ir/Mg-coated graphite tubes at 550-800°C. Selenium-75 radiotracer was used to measure the trapping efficiency and about 61% was obtained on an Ir-coated tube. Signal stability and reproducibility were tested over 400 trapping and atomization cycles. The adsorptive ''carryover effect,'' which can lead to errors in absorbance values, was observed with Te, not with Se, at trapping temperatures above 600°C (the ''critical temperature''). The characteristic mass is about 11 pg for Se and 12 pg for Te, and the detection limits (3s) are about 0.011 and 0.007 ng, respectively, on Ir-coated tubes using a 1 mL sample loop. The method was tested by determination of the elements in low-alloy steel certified reference materials. (C) 1997 Academic Press. 31 References
Alloy Spectrophotometry Preconcentration Volatile generation Reference material Volatile generation

"Utilization Of Dual Phase Gas Diffusion Flow Injection Analysis With A Mass Spectrometer As A Detector"
Anal. Lett. 1988 Volume 21, Issue 9 Pages 1619-1631
J. S. Canham; G. E. Pacey

Abstract: Hydrides of As and Se were generated in aqueous solution from which they diffused through a Goretex micro-porous membrane (0.45 µm pore size) into dry He for detection by MS. No mixed hydrides were observed. The detection limit for As was ~500 ng; that for H2Se was 1 µg. Tin and Sb were easily detected and did not interfere.
Mass spectrometry Gas diffusion Goretex Volatile generation Interferences Kinetic Volatile generation

"Interferences From Hydride-forming Elements On Selenium In Hydride-generation Atomic Absorption Spectrometry With A Heated-quartz-tube Atomizer"
Spectrochim. Acta B 1993 Volume 48, Issue 8 Pages 951-976
Bernhard Welz and Patrick Stauss

Abstract: Such interference was investigated with use of a Perkin-Elmer model MHS-20 Hg/hydride batch system and a Perkin-Elmer model FIAS-200 flow injection system. Ar was used as purge and carrier gas. In the batch system, a deficiency of radicals was the main reason for the low tolerance towards other hydride-forming elements. This, however, presented no problems in the flow injection system: with conditions optimized, tolerance limits were 1-2 orders of magnitude higher than with the batch system. The large differences in tolerance limits in the literature are interpretable in terms of the conditions or instrumentation used.
Spectrophotometry Interferences FIAS-200

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

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

"Flow Injection For The Determination Of Selenium(IV) And Selenium(VI) By Hydride-generation Atomic Absorption Spectrometry With Microwave-oven Online Prereduction Of Selenium(VI) To Selenium(IV)"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1837-1847
J. L. Burguera, P. Carrero, M. Burguera, C. Rondon, M. R. Brunetto and M. Gallignani

Abstract: The manifold is based on an Ismatec IPC eight-channel peristaltic pump and incorporates the time-based injector, controlled by a Gralab model 900 programmable timer, described previously (Carrero et al., Talanta, 1993, 40, 1967; Burguera et al., Anal. Chim. Acta, 1995, 308, 339), a Prolabo MW Microdigest oven mode l 301, and the gas-phase separator of Burguera etal. (Ibid., 1991, 261, 105). The carrier is 1% HCl and the 0.5% NaBH4 reductant solutions for Se(IV) and Se(VI) are in 4 M and 12 M HCl media, respectively. Further NaBH4 solution is added downstream of the microwave oven to keep the baseline stable. Se is determined at 196 nm. The response is linear for up to 120 µg/l of Se(IV) and 100 µg/l of Se(VI), and the detection limits are 1 and 1.5 µg/l, respectively. The RSD were 2.0-2.5% and the recoveries of Se(IV) and Se(VI) were 96-98% and 94-98%, respectively. The method has been applied to geothermal water and citrus juice.
Juice Geothermal Sample preparation Spectrophotometry Microwave Online digestion Speciation Phase separator

"Hydride-generation Flow Injection Using Graphite Furnace Detection - Emphasis On Determination Of Tin"
Spectrochim. Acta B 1992 Volume 47, Issue 5 Pages 701-709
Zhang Li, Susan McIntosh, Glen R. Carnrick and Walter Slavin*

Abstract: Hydride-forming analytes were separated from large volume of matrix by trapping the hydrides on a Pd-coated L'vov platform at low temperature before analysis by AAS. The Pd-treated stabilized-temp. platform furnace was used for in situ trapping and atomization of the analyte, and was at least 80% efficient for As, Bi, Ge, Sb, Se, Sn and Te. The method was tested by determining Sn in steel, river sediment, orchard leaves and bovine liver standard reference materials. The detection limit for Sn was 7 ng l-1, and the coefficient of variation was 31.5% at the 1.0 ng level. Other hydride-forming elements did not interfere.
Alloy River Plant Liver NIST 1571 NIST 1577 NIST 1645 Spectrophotometry Interferences Volatile generation Reference material Volatile generation

"Improvements In The Signal-to-background Ratio With Hydride Generation Inductively Coupled Plasma Atomic Emission Spectrometry"
Spectrochim. Acta B 1993 Volume 48, Issue 11 Pages 1339-1345
Hiroaki Tao*, Victor J. Boyko and James W. Mclaren

Abstract: An investigation of the effects of torch position and of diameter of the central tube of the ICP torch on signal-to-background ratio and reflected power in hydride generation inductively coupled plasma atomic emission spectrometry has identified conditions under which a stable plasma can be sustained at only 0.5 kW with a five times better signal-to-background ratio for Se than could be obtained at 1.4 kW. The improved performance is attributed to a more efficient introduction of hydrogen to the central channel of the plasma. [References: 15]
Spectrophotometry Membrane Signal noise

"The Use Of Nafion Dryer Tubes For Moisture Removal In Flow Injection Chemical-vapor-generation Atomic Absorption Spectrometry"
Spectrochim. Acta B 1995 Volume 50, Issue 4-7 Pages 369-375
Nils G. Sundin and Julian F. Tyson*, Christopher P. Hanna and Susan A. McIntosh

Abstract: A model MD-125 or MD-250 sheathed Nafion drying tube (30.5 cm x 1 or 2.2 mm, respectively; Perma Pure, Toms River, NJ, USA) was connected between the gas-liquid separator of a hydride- or cold vapor-generation unit and the absorption cell in place of the standard PTFE tubing. When 200 ml/min of dry Ar was passed through the sheath of either drying tube, water vapor was removed effectively in the determinations of As, Se and Hg at the cost of only a 3% decrease in peak-height sensitivity for As and Se and a 5% decrease for Hg. The detection limits for Hg with use of the PTFE tubing and the MD-125 and MD-250 tubes were 77, 150 and 20 parts per trillion, respectively.
Spectrophotometry Spectrophotometry PPT Nafion membrane Optimization

"Interferences In Hydride Atomization Studied By Atomic Absorption And Atomic-fluorescence Spectrometry"
Spectrochim. Acta B 1996 Volume 51, Issue 5 Pages 481-498
Alessandro D'Ulivo and Jiri Dedina

Abstract: A specially designed hydride atomizer able to operate in either the flame-in-tube or miniature diffusion flame atomization mode has been used to compare the extent of atomization interference mechanisms in these atomization modes. The specific atomization interference mechanisms were (i) depletion of the H radical population in the atomizer and (ii) 'decay' of the free analyte atom population caused by gas-phase or surface chemical reactions; the analyte was Se and the interfering element was As. Both AAS and AFS configurations with electrodeless-discharge lamps as sources were used, and liquid-phase interference was eliminated by use of a two-channel continuous-flow hydride generator. The miniature diffusion flame atomizer could tolerate up to 70 µg/ml of As. Interference mechanism (i) was negligible. All the observed interference was due to 'decay' of free analyte atoms in the atomizer free space, and could be reduced significantly by minimizing the distance between the atomization and observation positions, which is impossible for conventional quartz-tube atomizers.
Spectrophotometry Fluorescence Interferences

"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.
Environmental Sea Spectrophotometry Reference material Electrochemical product conversion Preconcentration

"Determination Of Selenium In Urine By Flow Injection Hydride Generation Electrothermal Atomic Absorption Spectrometry With In-atomizer Trapping"
Spectrochim. Acta B 1997 Volume 52, Issue 12 Pages 1773-1781
Julian F. Tysona,*, Nils G. Sundina, Christopher P. Hannab and Susan A. McIntoshb

Abstract: Following digestion of the sample in a mixture of bromate and hydrobromic acid, the inorganic selenium produced was quantified by trapping hydrogen selenide, formed when a 500 µL sample volume injected into a hydrochloric acid carrier stream merged with a stream of sodium borohydride solution, on the iridium-pretreated interior of a graphite furnace atomizer. A number of parameters relating to the digestion, flow injection manifold and trapping in the atomizer were investigated, including a study of factors affecting the detection limit. It was found necessary to heat the digest under reflux at a temperature of 150°C for 2 h. Quantitative recoveries, from a human urine matrix, of selenite, selenate, trimethylselenium, selenocystine, selenopurine and selenomethionine spikes were obtained. The efficiency of hydride generation, transport and trapping was 75%. The major factors affecting the detection limit were the reagent purity and the volume injected. For high-purity hydrobromic acid and borohydride free of caking agent, the detection limit, based on three times the standard deviation of the blank, was 0.06 µg L-1 for a 1000 µL injection volume corresponding to a detection limit of 3 µg L-1 for a urine sample. The method was validated by the accurate analyzes of Standard Reference Material 2670 from the National Institute of Standards and Technology, and urine samples from an interlaboratory comparison program. The procedure avoids the need for perchloric acid and produces selenium in the + 4 oxidation state and thus no reduction is needed prior to generation of the hydrogen selenide. The use of a graphite furnace atomizer avoids the need for frequent reconditioning of the atomizer surface and the need for the standard additions method, both of which are drawbacks of procedures which make use of the quartz tube atomizer. All sample handling procedures following the digestion were automated by the use of flow injection technology.
Urine NIST 2670 Spectrophotometry Sample preparation Reference material Standard additions calibration

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

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

"Determination Of Selenium By Flow-injection Analysis Based On The Selenium(IV)-catalyzed Reduction Of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium Bromide"
Anal. Sci. 1991 Volume 7, Issue 1 Pages 103-107
E. AOYAMA, N. KOBAYASHI, M. SHIBATA, T. NAKAGAWA and H. TANAKA

Abstract: Sample solution was mixed with NaOH (to pH 7) and 0.1 M phosphate buffer solution (pH 7) containing 12 mM bathocuproine disulfate and the mixture was injected into a carrier solution of 0.1 M phosphate buffer solution (0.2 mL min-1) and through a column (5 cm x 4.6 mm) of Chemcasorb 3-ODS-H operated at 40°C. The eluate was mixed with 7.3 mM dithiothreitol and 3-[4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide and the absorbance of the solution was measured at 565 nm. Analysis time was 8 min. The calibration graph was rectilinear for 1.3 pmol to 1.2 nmol Se (IV) and the coefficient of variation was 2.2%. The method was applied in the analysis of lobster refrence material, recovery was 103% for 5 µg mL-1 of Se and no interference was present.
NRCC TORT-1 Spectrophotometry Buffer Catalysis Column Heated reaction Interferences Solid phase reagent

"Flow Injection Analysis With Online Preconcentration Of Trace Selenium"
Anal. Sci. 1991 Volume 7, Issue 4 Pages 617-621
E. AOYAMA, K. AKAMATSU, T. NAKAGAWA and H. TANAKA

Abstract: The cited system (details given) was developed for determining very low concentration. of Se(IV). The Se was selectively collected as selenotrisulfide on a micro-column (5 cm x 1 mm) packed with resin loaded with Bismuthiol-II sulfonate and eluted with aqueous penicillamine solution The resulting penicillamine selenotrisulfide was introduced into the flow injection analyzer. (details given); detection was at 565 nm. Interference from Cu ion was eliminated by adsorption of Cu on the resin as bathocuproine disulfonate chelate. Determination of Se in a standard biological sample, e.g., lobster was used to confirm the reliability of the method.
Biological Spectrophotometry Column Interferences Preconcentration Resin Solid phase reagent

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

Abstract: A hydride-generation flow injection ICP-MS method for the determination of As and Se in river water is presented. For As, 100 mL water was boiled for 5 min with 1 mL concentrated HNO3, the pH was adjusted to 3.5 and the solution was applied to a Chelex 100 chelating resin. For Se, 100 mL water was boiled for 5 min with 2 mL concentrated HCl and the solution was applied to a chelex resin as above after pH adjustment. Both column eluate were diluted with water until the acidity became 0.1 M. Each sample was transferred in turn to the hydride generation system (schematic shown). Variable speed peristaltic pumps were used to mix sample solutions with 0.2% sodium tetrahydroborate(III) solution (both at 1 mL/min) in a Pyrex mixing coil (15 cm x 2 mm i.d.). The hydrides generated were swept continuously into the ICP torch (operating parameters given) and As and Se were detected by the MS operating at a resolution of 10,000 in selected-ion monitoring mode at m/z 75 and 82, respectively. Using standard solutions, the detection limits were 0.03 and 0.06 ng/ml, respectively, for As and Se. Interference levels of foreign ions on the determination of As and Se are listed. Results (tabulated) obtained the elements in NIST reference materials agreed with certified values. The concentration levels of As and Se in Japanese rivers close to industrial production sites were in the range 1.62-3.77 and 0.07-0.48 ng/mL, respectively.
River NIST 1640 Mass spectrometry Interferences Reference material Chelex Resin

"Determination Of Selenium In Copper Metal Using Flow Injection Hydride-generation Atomic Absorption Spectrometry With Continuous-flow Matrix Isolation"
Anal. Proc. 1991 Volume 28, Issue 1 Pages 18-20
Stephen G. Offley, Nichola J. Seare, Julian F. Tyson and Helen A. B. Kibble

Abstract: Selenium could be determined in copper sample solution by hydride-generation AAS, after removal of Cu by passage through a micro-column of Dowex 50W-X8 (H+ form). Optimum flow rate was 2 mL min-1 and optimum pH was ~2.0. The system and method of analysis are described in detail. Results for two reference samples agreed with certified values. The limit of detection was 2.1 ng mL-1 of Se, the coefficient of variation was 1.5% (n = 12) at 10 ng mL-1, and the sample throughput was 17 h-1.
Metal Spectrophotometry Column Reference material Matrix removal

"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%.
NIST 1643 NIST 1633 NIST 1648 Particulates Alloy Environmental Coal Fly ash River Sea Spectrophotometry Spectrophotometry Reference material FIAS-200 Nebulizer Volatile generation Volatile generation

"Development And Comparison Of Methods For The Determination Of Selenium In Biological Tissues And/or Fluids"
Acta Cient. Venez. 1983 Volume 34, Issue 5-6 Pages 449-449
Gallignani, M.;Burguera, J.L.;Burguera, M.

Abstract: NA
Biological fluid Biological tissue Clinical analysis Spectrophotometry Spectrophotometry Method comparison

"A Comparative Study Of Methods For Determining Selenium In Biological Materials"
Acta Cient. Venez. 1990 Volume 41, Issue 1 Pages 5-10
Burguera, J.L.;Burguera, M.;Gallignani, M.;Alarcon, O.M.

Abstract: A comparative study of the analytical performance of fluorimetric spectrophotometric, atomic absorption spectrometric, flow injection analysis with atomic absorption spectrometric, flow injection analysis with atomic absorption spectrometric detection, hydride generation with atomic absorption spectrometric detection and hydride generation with molecular emission cavity analysis detection methods has been carried out for the determination of selenium in biological materials. Based on results concerning detection limit, linearity and sensitivity, only the fluorimetric and hydride generation with atomic absorption spectrometric detection methods were suitable for the determination of selenium in biological materials. Whereas, the spectrophotometric, flame absorption spectrometric flow injection atomic absorption spectrometric and hydride generation with molecular emission cavity detection, due to its worse detection limits and poorer sensitivities, were found to be unsuitable for the determination of selenium in such matrices. The accuracy of the fluorimetric and hydride generation with atomic absorption spectrometric detection methods were tested by using NBS standard reference materials.
Biological material Spectrophotometry Fluorescence Spectrophotometry Spectrophotometry Detection limit Sensitivity Reference material Method comparison

"Investigations Into The Simultaneous Determination Of Bismuth And Selenium By 'in Atomizer Trapping' Electrothermal Atomic Absorption Spectrometry"
Anal. Commun. 1997 Volume 34, Issue 11 Pages 359-362
James Murphy, Phil Jones, Gerhard Schlemmer, Ian L. Shuttler and Steve J. Hill

Abstract: Initial investigations are described for the simultaneous determination of Bi and Se by hydride generation 'in atomizer trapping' electrothermal atomic absorption spectrometry. A fully automated micro-scale flow injection hydride generation system with 'in atomizer trapping' electrothermal atomic absorption spectrometry was employed. Using the recommended single element hydride generation conditions and optimized multi-element ETAAS parameters, simultaneous signals for Bi and Se were obtained. Calibration graphs were constructed in the range 0-5 g L-1 and method detection limits of 0.13 and 0.19 g L-1 for Bi and Se, respectively, established. Better than 2% precision was obtained for 3.0 g L-1 (n = 5) for Bi and Se. Carry-over effects were seen for Se and were reduced by the use of an internal atomizer gas flow during the 'in atomizer trapping' step.
Spectrophotometry Simultaneous analysis

"Optimization Of Microwave Digestion For Determination Of Selenium In Human Urine By Flow Injection-hydride Generation-atomic Absorption Spectrometry"
Anal. Commun. 1998 Volume 35, Issue 11 Pages 361-364
Fangshi Li, Walter Goessler and Kurt J. Irgolic

Abstract: A microwave digestion program, which completely decomposes and oxidizes selenium compounds in urine to selenate, was developed by monitoring the pressure and the temperature during microwave digestion. The efficient decomposition and quant. recovery of trimethylselenonium iodide spiked into urine was achieved in 18 min using the optimized microwave program reaching 200°C and 8 bar. The selenate in the digest was reduced to selenite by hydrochloric acid with the aid of microwave energy. Urea was found useful to eliminate NOx fumes, which might be absorbed in the digest and interfere in the determination of selenium by flow injection-hydride generation-at. absorption spectrometry (FI-HG-AAS). The recovery of trimethylselenonium iodide, selenomethionine, selenoethionine added to urine was 96.5-105%. The whole procedure, FI-HG-AAS determination following microwave digestion of urine sample and microwave reduction of selenate in the digests into selenite, was checked with two Standard Reference Materials 2670 (toxic metals in human urine). The results showed good agreement with the certified values (normal level 30 ± 8 µg Se L-1 and elevated level 460 ± 30 µg Se L-1). The detection limit of the whole procedure was 3 µg Se L-1 urine. Selenomethionine and selenoethionine were found unstable during the microwave heating used to reduce selenate to selenite. Such a microwave reduction procedure should be cautiously used to distinguish selenate from selenite in the matrixes which might contain organic selenium compounds
Urine NIST 2670 Spectrophotometry Sample preparation Interferences Reference material Optimization

"Improved Flow Injection Analysis Method For Determining Selenium In Biological Samples, And The Effect Of Captopril Administration On Selenium Levels And Glutathione Peroxidase Activity In Rat"
Biol. Pharm. Bull. 1993 Volume 16, Issue 11 Pages 1069-1072
Nobuyuki SUZUKI, Eriko FUJITA, Hiroyuki YASUI, Eiji AOYAMA, Hisashi TANAKA, Terumichi NAKAGAWA

Abstract: An improved flow injection analysis (FIA) method has been developed for the determination of trace selenium in biological samples, and this method has been applied to investigate the effect of captopril, an antihypertensive drug having a thiol group, on selenium concentrations in the rat blood, liver and urine. After oral administration of captopril, selenium levels in the blood decreased, while those in the liver increased significantly. However, no pronounced effect was observed on the urinary excretion rate. The glutathione peroxidase activities in the blood and the liver were comparable to the changes in the selenium levels.
Rat Blood Urine Liver

"Novel Flow Injection Analysis Of Trace Selenium Combined With Online Preconcentration"
Biomed. Res. Trace Elem. 1990 Volume 1, Issue 2 Pages 229-230
Aoyama, E.;Kobayashi, N.;Shibata, M.;Nakagawa, T.;Tanaka, H.

Abstract: A novel flow-injection method was developed for determining Se in biological samples. The method is based on the Se(IV)-catalyzed reduction of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide (MTT). The standard plot covered 1.3 pmol-1.2 nmol selenite with a detection limit of 0.63 pmol. Interference from copper ion could be eliminated by the online adsorption of Cu on an ODS column as a Cu-bathocuproine disulfate chelate. The utility of the method was demonstrated by determining Se in a standard sample. An online pre-concentration of selenite using an anion-exchange resin loaded with bismuthiol-II sulfate was incorporated in this flow-injection anal. system which enabled as low as 0.1 ppb Se to be determined.
Biological Preconcentration Interferences Resin

"Arsenic, Selenium And Mercury In Mineral And Curative Waters"
Brauwelt 1990 Volume 130, Issue 37 Pages 1588-1591
Meier, B.;Dietschmann, U.;Gigl, C.;Seberich, M.;Postel, W.

Abstract: The three elements were determined by AAS following hydride reduction in a flow injection system. For the determination of As, sample was mixed with HCl and KI solution (5% KI and 5% ascorbic acid), injected into a carrier of 2% HCl and reduced with NaBH4 in NaOH. The same carrier and reagent were used for the determination of Se, reduced by heating (90°C, 20 min) the sample with HCl (12 min) and diluting with water. Organic forms of Hg were converted to ionic forms by shaking the sample with HNO3, KMnO4 and water. The sample was injected into a carrier of KNO3 and reduced with NaBH4 in NaOH. The metallic Hg formed was amalgamated with Au or Pt gauze and was released into a stream of Ar by heating (600°C) for AAS analysis. The detection limits were 0.3, 0.6 and 0.1 µg L-1 for As, Se and Hg, respectively. The coefficient of variation (n = 20) were 2.9% (As and Se) and 5.2% (Hg). Results are discussed for the analysis of 44 mineral waters and six curative waters.
Mineral Curative Spectrophotometry Spectrophotometry Dilution Volatile generation Amalgamation Volatile generation

"Determination Of Arsenic And Selenium In Coal And Fly Ash By Continuous-flow Hydride-generation ICP-AES"
Bunseki Kagaku 1987 Volume 36, Issue 9 Pages T95-T99
Etoh, M.

Abstract: Coal was digested with HNO4 and HClO3 and fly ash was digested with HNO3 and H2SO4. The As and Se were separated from co-existing elements (except for Sb, Sn and Ge) by distillation with HBr and Br. Arsenic and Se were determined by continuous-flow hydride-generation ICP-AES. Recoveries were 98 to 104%, and coefficient of variation were 2.4 to 3.5 and 2.7 to 4.5%, respectively, for As and Se. Tin, Sb and Ge did not interfere at concentration. present in the samples used.
Coal Coal Fly ash Sample preparation Spectrophotometry Interferences

"Determination Of Arsenic And Selenium By Hydride Generation Atomic Absorption Spectrometry (flow Injection Or Continuous-flow) Method Combined With A Hydride Collecting Trap"
Can. J. Anal. Sci. Spectrosc. 1995 Volume 40, Issue 5 Pages 117-124
Siska, R.;Borszeki, J.;Gegus, E.

Abstract: A hydride collecting cold trap hydride generation AAS method has been developed using a flow injection (FI) or a continuous-flow (CF) system, applicable to the high sensitivity determination of arsenic and selenium, characterized by a detection limit of 10^-20 pg/mL. The best relative detection limits and sensitivity for this system could be achieved using the CF operation mode. Accuracy and reproducibility of the method were investigated by the analysis of dilute solutions produced by decomposition of international CRM samples of various types. The results of the determinations agree well with the certified values. Reproducibility of the measurements is good considering especially the extreme low initial concentrations. The remarkable feature of the method is the relatively low blank value which is partly due to the use of high purity acids and reagents, and partly to the very low risk of contamination when the work is done in a closed system. Further on, several water samples were investigated by this method, the arsenic and selenium content of which could not be determined previously. Also numerous food samples having low content of As and Se were analyzed. (12 references)
Food Water Spectrophotometry Cold trap Optimization Reference material Volatile generation Volatile generation

"Recent Developments In Speciation Analysis Of Selenium"
Chem. Anal. 1995 Volume 40, Issue 5 Pages 677-686
Pyrzynska, K.

Abstract: The review concerns the specific problems of selenium speciation analysis. The distribution of the element, sample storage, its decomposition prior to analysis as well as the pre-concentration and separation techniques is discussed. Recent developments in the determination of inorganic and organic selenium compounds are presented. (124 references)
Environmental Spectrophotometry Mass spectrometry Spectrophotometry GC Review Speciation Preconcentration

"Determination Of Trace Amounts Of Selenium In Environmental Samples By Hydride-generation Atomic Absorption Spectrometry Combined With Flow Injection Analysis"
Fenxi Huaxue 1986 Volume 14, Issue 10 Pages 738-743
Wang, X.;Fang, Z.L.

Abstract: Selenium in environmental materials was determined by the cited technique with a detection limit of 0.06 ng mL-1 and a coefficient of variation of 1.6% at 4 ng mL-1 of Se. The sampling frequency was 250 to 300 h-1 with use of 0.4 mL injections. Results obtained with use of NBS Standard Reference Materials were in good agreement with certified values. Interference was not as high as in other methods. Sample pre-treatment methods are given.
Environmental Spectrophotometry Interferences Reference material

"Flow Injection Catalytic Spectrophotometric Determination Of Trace Selenium In The Presence Of Nonionic Surfactants. 1"
Fenxi Huaxue 1991 Volume 19, Issue 4 Pages 433-435
Qi, W.;Chen, X.G.

Abstract: Sample was dissolved in concentration. HNO3, the solution was treated with 1 to 2 mL of HNO3 - HClO4 (5:1) and evaporated to dryness. The residue was dissolved with water and acidified. The solution was passed through a cation-exchange column, the eluate was mixed with 2 mL of 5% hydroxylamine hydrochloride solution, and the mixture was concentrated and neutralized. The solution was analyzed by the cited method in a flow injection system (diagram given). Sample solution (250 µL) was injected into a carrier stream at 1.8 mL min-1 for reaction at pH 9.2 with 3.7 mM Fe3+, aqueous 0.5% triethanolamine, 5.4 mM EDTA, 11.3 mM Na2S, aqueous 2% Tween 80, aqueous 0.375% Na2SO3, 0.4 mM methylene blue and aqueous 10% formaldehyde in a 1-m reaction coil. The method was applied to hair; bivalent Cu and Fe3+ did not interfere. The calibration graph was rectilinear from 0.1 to 0.5 µg g-1 of Se and the detection limit was 8 ng g-1.
Hair Spectrophotometry Catalysis Column EDTA Interferences Surfactant

"Determination Of Trace Arsenic, Selenium, Molybdenum, Sulfur And Chromium With Online Flow Injection Anion-exchange Preconcentration Inductively Coupled Plasma Atomic-emission Spectrometry"
Fenxi Huaxue 1993 Volume 21, Issue 3 Pages 328-330
Liu, E.;Chen, W.J.;Zhao, C.Y.

Abstract: A system for online flow injection anion-exchange pre-concentration. ICP-AES (diagram given) for determination of As, Se, Mo, S and Cr is described. Sample solution was passed through two parallel columns (8 cm x 2 mm) packed with D296 anion-exchange resin (40 mesh) at a flow rate of 1.23 mL min-1 for pre-concentration.; elution was effected with 0.5 M NH4Cl and 3 M NH3 (1.23 mL min-1) and exposure time was 40 s. The detection limits were 13, 25.2, 2.04, 6.19 and 3.64 ng mL-1 for As, Se, Mo, S and Cr, respectively. The method was used for the analysis of geological, hair and bovine liver standards. Results agreed with the certified values.
Geological Hair Cell Spectrophotometry Sample preparation Ion pair extraction Reference material Preconcentration

"Study On Application Of Flow Injection Analysis - Hydride-generation Graphite-furnace Atomic Absorption Spectrometry. 1. The Experimental Device And Its Analytical Property"
Fenxi Shiyanshi 1993 Volume 12, Issue 1 Pages 87-90
Ma, Y.P.

Abstract: A semi-automatic sampling device for introduction of hydride into the graphite furnace and a flow injection hydride generator were developed. Detection limits were optimized and interferences were eliminated in the liquid and gas phases by the decomposition and deposition of the hydride on the graphite tube wall at low temperature followed by atomization at high temperature The device was used to determine Hg, As, Se, Sb, Sn and Bi without any modification to the graphite furnace. Results were compared with those obtained by conventional hydride-generation AAS and graphite-furnace AAS.
Spectrophotometry Volatile generation Method comparison Optimization Interferences Phase separator Volatile generation

"Automated Determination Of Arsenic, Antimony, Selenium And Mercury In Water"
GIT Fachz. Lab. 1997 Volume 41, Issue 5 Pages 475-476
Sinemus, H.W.;Stabel, H.H.;Kleiner, J.;Radziuk, B.

Abstract: The hydride-forming elements and Hg were concentrated by pumping the sample and the reducing solution (NaBH4 or SnCl2, respectively) into a manifold, entraining the hydride or Hg vapor in Ar and introducing the gas stream into a pyrolytic graphite tube equipped with an Ir-coated platform for AAS determination. The operating program of the automated system is shown. For the determination of As, Sb and Se, samples were collected in fluorinated ethylene/propene or polyethylene terephthalate co-polyester vessels and stabilized with 0.2% HCl, and were treated with 37% HCl, KI, ascorbic acid, hydroxylammonium chloride and sulfamic acid to reduce As and Sb in higher oxidation states or with 37% HCl, sulfamic acid and ammonium sulfate to reduce Se(VI). Samples to be analyzed for Hg were collected in hard glass vessels and stabilized with HNO3/potassium dichromate and H2SO4. Organic Hg compounds were decomposed ultrasonically in the presence of KMnO4 and ammonium persulfate. Hydroxylammonium chloride was added to reduce permanganate before the analysis. Very small amounts of Hg were pre-concentrated on Au/Pt gauze. Characteristic masses for As, Sb and Se were 24, 38 and 45 pg, respectively. Down to 3 ng/l of Hg could be detected.
Water Sample preparation Spectrophotometry Preconcentration Volatile generation Automation Volatile generation

"Determination Of Trace Selenium In Blood By Hydride-generation Atomic Absorption Spectrophotometry Combined With Flow Injection Analysis"
Guangpuxue Yu Guangpu Fenxi 1993 Volume 13, Issue 5 Pages 103-106
Li, L.;Zhang, S.C.

Abstract: Blood (0.2 ml) was decomposed with 15 mL of HNO3/HClO4 (3:1) at 180°C prior to boiling with 2 mL of 4 M HCl and dilution with water to 10 mL. A 0.4 mL portion of the solution was injected, carried by a stream of 1 M HCl, to react with a stream of 0.5% KBH4 (containing 0.1% NaOH) at 2 ml/min in a tube (20 cm in length). The mixture was transported at 0.15 ml/min to a U-shape gas-liquid separator where the generated gaseous hydride was carried to an atomic absorption spectrophotometer with Ar at flow-rate of 50 ml/min for AAS. Atomization temperature was 700°C and absorbance was measured at 196 nm. Recovery was 90-102% and the detection limit was 0.06 µg/l. In presence of 16-20% HClO4, interference of 1 µg/ml of As3+ on the assay of 8 ng/ml of Se could be overcome. The method was also applied to serum. Sampling frequency was 120-150 runs per h.
Blood Serum Spectrophotometry Interferences

"Comparison Of The Analytical Performances Of Membrane And U-tube Phase Separators For Flow Injection Hydride-generation Atomic-fluorescence Spectrophotometry"
Guangpuxue Yu Guangpu Fenxi 1995 Volume 15, Issue 1 Pages 69-74
Lin, S.L.;Lu, C.G.;Tong, Z.Y.;Chiu, H.

Abstract: Analytical performances of the two set-ups were compared in terms of sensitivity, detection limit, precision, suppression of interferences and simplicity of operation with As, Sb, Bi, Se and Te as the analytes. Both membrane and U-tube phase separators performed similarly and could be used in the assay of geochemical samples. However, the membrane separator had a shorter lifespan and required frequent renewal.
Fluorescence Membrane Phase separator Interferences Volatile generation Volatile generation

"Simultaneous Determination Of Arsenic, Selenium, And Antimony In Environmental Samples By Hydride Generation For Inductively Coupled Plasma Atomic-emission Spectrometry"
J. AOAC Int. 1995 Volume 78, Issue 4 Pages 1055-1060
Kim A. Anderson and Brandon Isaacs

Abstract: Two digestion procedures (details given) were used in which a 1 g wet, 0.25 g dry or a 10 mL water sample was heated on a programmed heating block with HNO3 followed by boiling in H2SO4/HClO4. Soils (0.25 g) were digested with HCl. After digestion, the samples were treated with HCl. As, Se and Sb were reduced simultaneously in a continuous-flow manifold (diagram given) by mixing with NaBH4 and HCl-KI. The resulting hydrides (SeH2, SbH3 and AsH3) were separated by a Meinhard nebulizer. ICP-MS was performed with use of a Model Perkin-Elmer P-40 ICP with measurements at 193.696, 196.026 and 231.147 nm for As, Se and Sb, respectively. The detection limits were 0.55, 1 and 0.41 µg/l for As, Se and Sb, respectively. Their corresponding recoveries were 81-109, 87-108 and 65-123%. The method had good precision and accuracy (RSD not stated).
Environmental Mass spectrometry Sample preparation Simultaneous analysis Volatile generation Volatile generation

"Optimization Of Selenium Determination In Human Milk And Whole Blood By Flow Injection Hydride Atomic Absorption Spectrometry"
J. AOAC Int. 1998 Volume 81, Issue 2 Pages 457-461
Amparo Alegr&iacute;a, Reyes Barber&aacute;, Rosaura Farr&eacute;, Emilia Ferrer, M. Jes&uacute;s Lagarda, M. Angeles Torres

Abstract: A flow injection hydride atomic absorption spectrometric (FI-HAAS) method was developed for determining selenium in human milk and whole blood after microwave digestion of the sample. The sample (2 mL human milk or 0.25 mL blood) was introduced into the microwave vessel with 1.5 mL HNO3 and 0.25 mL H2O2 and 300 W (4 min) and 600 W (4 min) were applied. The digestion was completed by heating to 140°C (2-3 h). Se(VI) was reduced to Se(IV) with HCl. The instrumental conditions for FI-HAAS (concentrations of reducing agent and carrier acid, flow rate of Ar carrier gas, and sample volume injected) were optimized. The detection limit of the proposed method was 0.23 ng/mL (assay) or 115 pg Se (abs.) in biological samples (1.15 ng/mL milk, 10.4 ng/mL blood). The precision values were 5.0% for milk and 4.0% for blood. The accuracy was evaluated with two NIST reference materials. Non-Fat milk powder (found: 104.3 ± 7.2 ng/g, certified: 110 ± 10 ng/g) and whole blood seronorm (found: 81 ± 7.3 ng/mL, ref.: 83 ± 4 ng/mL). The results show the suitability of the method for Se determination in human milk and whole blood. The method was applied to whole blood samples obtained from pregnant women and to human milk.
Milk Whole Human NIST 1549 Spectrophotometry Sample preparation Reference material Optimization

"Determination Of Arsenic And Selenium In Whole Fish By Continuous-flow Hydride-generation Atomic Absorption Spectrophotometry"
J. AOAC Int. 1989 Volume 72, Issue 3 Pages 484-486
Brumbaugh WG, Walther MJ

Abstract: Freeze-dried homogenized fish tissue (~0.5 g) and 2 to 3 mL of methanol were mixed with 5 drops of anti-foaming agent, 10 mL of 40% Mg(NO3)2.6H2O and 10 mL of HNO3, and the mixture was heated under reflux at 70°C to 80°C overnight. The temperature was increased to 200°C, the mixture was evaporated to dryness and the residue was placed in a cold muffle furnace. The temperature was increased to 500°C over 3 to 4 h (held for 2 to 4 h), the mixture was cooled, 20 mL of 50% HCl was added and the solution was boiled for 1 h on a hot plate. After cooling, the volume was adjusted to 20 mL with 50% HCl and As and Se in the solution were determined by hydride-generation AAS at 193.7 and 196.0 nm, respectively, with 0.6% NaBH4 - 0.5% NaOH and 1% NaBH4 - 0.5% NaOH as reductants for Se and As, respectively. Detection limits were ~0.06 and ~0.04 µg g-1 for As and Se, respectively, and the average coefficient of variation for both elements was 4%.
Fish Tissue Sample preparation Spectrophotometry Volatile generation Volatile generation

"Continuous-flow Vapor Generation For Inductively Coupled Argon Plasma Spectrometric Analysis. 1. Selenium"
J. AOAC Int. 1990 Volume 73, Issue 3 Pages 404-410
Tracy ML, M&ouml;ller G.

Abstract: Sample (~1.5 g of solid or ~10 mL of liquid) is wet ashed with HNO3, H2SO4 and HClO4 at ~310°C; details are presented for treatment of different samples. The digest is cooled to room temp., 5 M HCl is added and the solution is diluted. In a simple continuous-flow manifold, sample solution is mixed with 12 M HCl and then 0.6% NaBH4 solution The H2Se produced is separated off by a standard pneumatic neublizer, and Se is determined by ICP-AES at 196.090 nm. The detection limit is 0.4 µg l-1, or 4 µg kg-1 for a nominal 1-g sample. The calibration graph is rectilinear for 4 mg kg-1. The method has been applied to biological tissues and fluids and to water. Results show good agreement with those by AAS and NAA.
Biological tissue Water Spectrophotometry Dilution Nebulizer Detection limit Calibration

"Design Considerations For An Automated Hydride-evolution System Based On Continuous-flow Principles"
J. Autom. Methods Manag. Chem. 1980 Volume 2, Issue 3 Pages 134-138
A. L. DENNIS and D. G. PORTER

Abstract: Environmental concentrations of elements such as arsenic, selenium and, to a lesser extent, antimony, are of considerable interest because of their potential toxicity. The Laboratory of the Government Chemist is called on to monitor levels of arsenic and selenium in water and very sensitive methods for their measurement are therefore required. Investigations have shown that adequate sensitivity can be obtained by using a modification of an automated hydride evolution procedure developed by Goulden and Brooksbank [1]. This procedure utilises continuous flow techniques to generate the hydrides which are then fed to an on-line atomic absorption spectrometer. One of the inherent advantages of automation, compared with a manual approach, is that more precise control can be maintained in a routine environment. A very rigid control of both gas and liquid flows is essential for the successful operation of a continuous flow hydride evolution system, and this paper will describe the developm/ent of an automated system that has worked routinely in the authors' laboratory for several years, and which forms the basis of a commercially available system. The construction is modular and where possible readily available commercial-components have been used. Particular attention has been paid to the safe and consistent pumping of corrosive materials and of slurries. The performance and potential for further development of the system will be discussed.
Environmental Spectrophotometry Apparatus Volatile generation Volatile generation

"Ultratrace-level Detection Of Arsenic And Selenium Using A Commercially Available Hydride Generator With Atomic Absorption Detection"
J. Autom. Methods Manag. Chem. 1983 Volume 5, Issue 4 Pages 193-196
R. W. WARD and P. B. STOCKWELL

Abstract: The Plasma-Therm continuous-flow hydride generator (illustrated) is based on the NaBH4 system. The apparatus has been applied in generation of the hydrides of, e.g., As and Se for determination by AAS or ICP-AES Detection limits by AAS are 0.04 and 0.07 ng mL-1 for As and Se, respectively, and response is rectilinear for up to 80 or 120 ng mL-1 of As or Se, respectively. The apparatus requires comparatively little operator expertise; it can accept and relay signals to an external computer, so facilitating control and data handling.
Spectrophotometry Spectrophotometry Ultratrace

"Catalytic Photometric Determination Of Selenium By Flow Injection Analysis"
J. Chin. Chem. Soc. 1986 Volume 33, Issue 2 Pages 109-115
Hwang; T. S. We; Y. M. Chen

Abstract: Catalytic enhancement by Se of the reduction of picrate ion by Na2S was measured photometrically at 470 nm. The optimum reaction conditions were pH 9.8, 60°C, 0.0125 M picrate and 0.25 to 0.5 M Na2S. Optimum sample volume was 140 µL, the flow rate was 1.4 mL min-1 and the mixing coil length was 225 cm. Interference by diverse metal ions was avoided by incorporating a pre-column exchanger and by masking with EDTA. Response was rectilinear for 0.1 to 1.0 ppm of Se and the detection limit was ~5 ppb. The method was developed for use with water samples.
Environmental Spectrophotometry Catalysis Heated reaction Interferences

"An Automated Microtechnique For Selenium Determination In Human Body Fluids By Flow Injection Hydride Atomic Absorption Spectrometry"
J. Trace Elem. Electrolytes Health Dis. 1990 Volume 4, Issue 1 Pages 41-48
Negretti de Bratter VE, Bratter P, Tomiak A

Abstract: The automation of a flow injection system for the hydride generation of selenium and its subsequent determination by atomic absorption spectrometry (FI-HAAS) is described. Pre-treatment of the sample and the details of the automated equipment are reviewed. For the FI-HAAS selenium analysis a volume of 350 µL of acid-digested sample solution is injected. The online generated hydride is delivery by the gas-liquid separator and is transported together with an Ar stream to the heated quartz cell for the atomic absorption determination. The absolute detection limit is 35 pg Se; the relative detection limit 0.10 µg/L Se. The absolute determination limit in real biological samples is 110 pg Se; the relative detection limit 0.31 µg/L Se. The accuracy of the method was evaluated via analysis of certified standard reference materials. Quality control was made by comparing FI-HAAS and instrumental neutron activation analysis (INAA), as an independent analytical method. Two acid-digestion procedures (in open vessels at atmospheric pressure and bomb-digestion in pressure vessels) were experimentally tested. To determine the effectiveness of the selenium reduction and the completeness of the selenium hydride formation a parallel selenium determination was carried out by means of ICP-AES and FI-HAAS analysis. FI-HAAS was applied for blood serum analysis of children undergoing long-term total parenteral nutrition, as well as of persons with high dietary selenium intake, and for human milk analysis. Human serum or milk (150 µL) is digested overnight with 1 mL of concentrated HNO3, a further 1 mL of HNO3 is added, and the sample is ashed for 1 h at 170°C. After addition of 100 µL of H2SO4 and 50 µL of HClO4, the sample is ashed for a further 1.5 h. Alternatively bomb-digestion is performed for 5 h at 160°C. The digest is diluted to 3 mL with 5 M HCl and heated at 95°C for 30 min for reduction of Se(VI) to Se(IV). A 350 µL portion of this solution is injected into a water carrier stream (2.2 mL min-1) that is subsequently mixed with streams of HCl (2.2 mL min-1) and alkaline 3% NaBH4 (0.44 mL min-1). The reaction mixture is passed into a gas - liquid separator and the H2Se formed is swept by Ar (0.3 l min-1) into a heated silica tube, where it is atomized at 900°C for detection of Se at 196.0 nm. Calibration graphs are rectilinear for 0.87 to 8.7 ng of Se injected and the limit of detection is 0.1 µg l-1. Results for four biological standard reference materials (including NBS Bovine Serum and Oyster Tissue) agreed well with certified values. Results for Se in human serum or milk generally agreed well with those obtained by instrumental NAA.
Serum Human Milk NIST 1566 NIST 1598 Sample preparation Spectrophotometry Automation Detection limit Reference material Calibration Phase separator Volatile generation Method comparison Review Volatile generation

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

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

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

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

"Coupling Of Microwave Digestion And Hydride AAS"
LaborPraxis 1993 Volume 17, Issue 4 Pages 44-48
Meyer, A.;Schwedt, G.

Abstract: An automated system is described for the interference-free determination of As and Se in protein-containing samples (serum and urine) without the need for sample separation. In the flow injection system, the sample is pumped with a digestion reagent through a coil in a microwave apparatus ('Maxidigest') and the product is injected into a stream of HCl carrier and reacted with sodium borohydride. After gas-liquid separation, the hydride gas is subjected to AAS. Optimization of the system is discussed.
Blood Serum Urine Sample preparation Spectrophotometry Microwave Automation Online digestion Interferences Phase separator Optimization

"Determination Of Arsenic And Selenium By Injection Combined With Cold-trap Collection Of Hydride And Continuous-flow Hydride Atomic Absorption Technique"
Magy. Kem. Foly. 1996 Volume 102, Issue 3 Pages 248-256
Siska, R.;Borszeki, J.;Gegus, E.

Abstract: Continuous-flow and flow injection hydride-generation AAS methods for the determination of As and Se are described, which involve collection of hydrides in a cold trap (diagrams of manifolds given). The detection limits were 10^-20 pg/ml. The results obtained for international standards agreed with the internationally accepted values. Reproducibility was good. The methods were applied to environmental materials (food and water).
Environmental Food Water Spectrophotometry Cold trap Reference material

"Notes And Comments On The Determination Of Selenium In Biological Materials"
Norwegian J. Agric. Sci. 1993 Volume 11, Issue 1 Pages 57-74
Galgan, V.;Frank, A.

Abstract: This short review considers the most frequently used sample preparation procedures and analytical techniques for estimating selenium in biological materials. Automated wet ashing using a mixture of HNO3/HClO4, and flow injection hydride-generation atomic absorption spectrometry (FI-HG-AAS) are discussed in detail. Automated wet ashing has been used successfully for many years. More recently experience in method development and in comprehensive routine work has been achieved by using automated and computerized FI-HG-AAS. Other methods have more or less comparable sensitivity and detection limits, thus choice of method is mainly influenced by economics and practical/routine requirements. Available equipment, staff, type and quality of sample, length of sample series and expected Se concentrations are all decisive factors in choice of method.
Biological Sample preparation Spectrophotometry Reverse Review

"A Critical Survey Of Hydride Generation Techniques In Atomic Spectroscopy"
Pure Appl. Chem. 1992 Volume 64, Issue 2 Pages 227-244
A. D. Campbell

Abstract: A review with 134 references. Formation of the hydrides of antimony, arsenic, bismuth, germanium, lead, selenium, tellurium and tin by reaction with sodium tetrahydroborate(III) affords an excellent method for the separation of these elements as gases from a wide range of matrixes. Excellent low limits of detection are attained when this separation method is combined with atomization of the hydride in a heated quartz tube in the optical axis of a conventional atomic absorption spectrometer but there are many interferences to contend with both at the hydride generation stage and in the atomization process. Hydride generation is also used in conjunction with inductively coupled plasma (ICP) emission spectrometers. It is particularly useful for the determination of arsenic and selenium which suffer considerable spectral interferences caused by radicals in flame atomic absorption spectrometry. Implications of recent advances in the application of this separation procedure for the determination of hydride forming elements by atomic absorption and also ICP atomic emission spectrog. techniques are discussed.
Spectrophotometry Spectrophotometry Review Volatile generation Interferences Volatile generation

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

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

"Pneumatic Nebulizer As A Dilution Chamber In A Flow Injection System For Multielement Analysis By ICP-MS"
Quim. Nova 1998 Volume 21, Issue 4 Pages 405-409
Gomes Neto, Jos&eacute; Anchieta; Silva, Jos&eacute; Bento B.; Rodrigues Neto, Renato; Curtius, Adilson Jos&eacute;; Souza, Ivan G.

Abstract: An automatic dispenser based on a flow injection system used to introduce sample and anal. solution into an inductively coupled plasma mass spectrometer through a spray chamber is proposed. Anal. curves were constructed after the injection of 20 to 750 µL aliquots of a multielement standard solution (20.0 µg L-1 in Li, Be, Al, V, Cr, Mn, Ni, Co, Cu, Zn, As, Se, Sr, Ag, Cd, Ba, Tl, Pb) and the acquisition of the integrated transient signals. The linear concentration. range could be extended to ~five decades. The performance of the system was checked by analyzing a NiST 1643d reference material. Accuracy could be improved by the proper selection of the injected volume Besides good precision (relative standard deviation <2%), the results obtained with the proposed procedure were closer to the certified values of the reference material than those obtained by direct aspiration or by injecting 125 µL of several anal. solutions and samples.
NIST 1643 Mass spectrometry Dilution Nebulizer Reference material

"Survey Of Bioavailable Selenium In Sweden With The Moose (Alces Alces L.) As Monitoring Animal"
Sci. Total Environ. 1995 Volume 172, Issue 1 Pages 37-45
Vera Galgan* and Adrian Frank

Abstract: Liver tissues were collected from moose (Alces alces L.) from the regular hunting seasons of 1981 and 1982. The material (from about 4300 animals) was stored at -20°C at the National Veterinary Institute (SVA). From this material, 2080 specimens from 12 counties representing 14 regions were analyzed for selenium. The counties included were Norrbotten, Västernorrland (northern region), Uppsala, Kopparberg, Gävleborg, Jämtland (central region), north and south Kalmar (eastern region), Halland, north and south Alvsborg (western region), and Blekinge, Kristianstad and Malmöhus (southern region). The analysis was performed by a combination of continuous hydride generation using a flow injection technique and atomic absorption spectrometry. The median selenium concentration in the liver in the entire material was 0.15 and the mean (± S.D.) 0.25±0.29 (range: 0.03-3.1) mg/kg wet wt. The highest median values obtained were 0.26, 0.28 and 0.29 mg/kg, in the counties of Gävleborg (central region) and north and south Alvsborg (western region), respectively. The lowest medians, 0.09-0.10 mg/kg, were found in the counties of Uppsala (central region), north and south Kalmar (eastern region), and Jämtland (central region). Intermediate median values were obtained in the other counties: 0.13 mg/kg in the county of Västernorrland (northern region), 0.15-0.16 mg/kg in the counties of Blekinge and Malmöhus (southern region) and Norrbotten (northern region), 0.18 mg/kg in the county of Halland (western region), and 0.23 mg/kg in the counties of Kristianstad and Kopparberg (southern and central regions, respectively). Selenium concentrations < 0.1 mg/kg in the liver of cattle are considered to be deficient. In some of the regions, 50-60% of the moose livers showed values below this level. The results indicate that the moose is useful for monitoring the amount of selenium available for wild-grazing animals and confirm that the Swedish environment is poor in selenium. (28 References)
Liver Spectrophotometry Volatile generation Volatile generation

"Comparison Of Four Wet Digestion Procedures For The Determination Of Selenium In Eggs By Hydride Generation-flow Injection Atomic Absorption Spectrometry"
Shipin Yu Fajiao Gongye 1987 Volume 4, Issue 4 Pages 7-9
Sun Junyan

Abstract: A comparison was made between four different wet digestion methods for the determination of Se in eggs by hydride generation AAS using a flow injection system. The coefficient of variation for the HNO3-HClO4 HNO3-(NH4)2S2O3 and HNO2-pr-essurized teflon bomb methods were, 6.7-9.9%, 7.4% and 7.6% respectively, and the percentage recoveres were 90-105%, 92% and 97% respectively. The HNO3-H2SO4 method was not able to decompose the organic material completely, and the sample was easily carbonized giving low results.
Whole Egg Sample preparation Spectrophotometry

"Selenium Distribution In Egg White Proteins"
Z. Lebensm. Unters. Forsch. 1993 Volume 196, Issue 3 Pages 236-238
Kristin Jacobs, Lihua Shen, Hilary Benemariya and Hendrik Deelstra

Abstract: The present studies were undertaken to characterize selenium distribution in egg white. Ion-exchange chromatography fast protein liquid chromatography (FPLC) and flow injection atomic (absorption) spectrometry (FIAS) were used to separate egg white proteins and to determine the selenium content of different fractions. After purification, nine different proteins were identified with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 56% of the total selenium content was found to be associated with ovalbumin-1 and -2 (± 500 ng/g), which is the main protein in egg white. Flavoprotein was determined to be the richest selenium-containing protein (1800 ng/g). The selenium content of the other proteins (lysozyme, conalbumin, globulins and ovomucoid) ranged from 359 to 1094 ng/g.
Egg White Spectrophotometry

"Actual Daily Dietary Intake Of Selenium In Belgium, Using Duplicate Portion Sampling"
Z. Lebensm. Unters. Forsch. 1994 Volume 199, Issue 4 Pages 251-254
Harry J. Robberecht, Peter Hendrix, Rudy Van Cauwenbergh and Hendrik A. Deelstra

Abstract: The dietary selenium (Se) intake in Belgium has been re-evaluated. Duplicate meal collection, wet acid destruction and flow injection hydride generation atomic absorption spectrometry were used as techniques. The daily intake ranged from 28.4 µg (Liège, Walloon part of the country) to 61.1 µg (Vilvoorde, central part of the country). Compared with intakes recently published for other countries, the actual Belgian value corresponds to intermediate ranges of Se intake.
Food Spectrophotometry Volatile generation Volatile generation

"Determination Of Selenium In Vegetables By Hydride Generation Atomic Fluorescence Spectrometry"
Anal. Chim. Acta 2004 Volume 512, Issue 1 Pages 11-17
P. Smrkolj and V. Stibilj

Abstract: A digestion mixture of H2SO4/HNO3/H2O2/HF/V2O5 was investigated for decomposition of plant samples and sensitive detection of selenium was achieved by hydride generation atomic fluorescence spectrometry (HG-AFS). The method was found to be accurate and reproducible, with a low detection limit (DL) (0.14 ng g-1 solution). The repeatability of the determination was mostly around 10%, the reproducibility over a period of 8 months for determination of selenium in the standard reference material Trace Elements in Spinach Leaves, NIST 1570a, was 9% and the relative measurement uncertainty was 7% using a coverage factor of 2.3 at 95% probability. The average recovery of the whole procedure was 90%. The characteristics of this method are simple and inexpensive equipment, low consumption of chemicals and the ability to analyze many samples in a short time. The whole procedure was carried out in the same PTFE tube, and in addition only a simple cleaning procedure is needed. As a consequence of all these advantages, the described method is suitable for environmental and nutritional studies. The selenium content was determined in 44 vegetable samples from different regions of Slovenia and the contents found were in the range 0.3-77 ng g-1 wet weight.
NIST 1570 Vegetable Vegetable Fluorescence Reference material Volatile generation

"Double Hydride Generation Gaseous Phase Enrichment With Flow Injection On‐line Automatic Preparation For Ultratrace Amounts Of Total Selenium Determination By Atomic Fluorescence Spectrometry"
Spectrosc. Lett. 2005 Volume 38, Issue 1 Pages 131-143
Xuming Guo, Shuping Li, Benli Huang

Abstract: A double hydride generation technique was developed and successfully used for the determination of total ultratrace amounts of selenium by atomic fluorescence spectrometry (AFS). In this technique, the acid digested sample solution was used for the generation of selenium hydride first, after which, the SeH2 formed was reacted with, and absorbed in, a small volume of alkaline solution (0.5 mol L-1 NaOH+0.05 mol L-1 H2O2), in which automated organic selenium digestion by the flow injection technique was pursued. The alkaline solution with the selenium absorbed was mixed with the reductant and then acidified to achieve hydride generation for the second time. The concentration factor depends on the volume ratio of the sample and the alkaline solution. Selenium hydride was atomized in a quartz atomizer with a mini-hydrogen diffusion flame and detected by AFS. Under the conditions employed, a detection limit of 2-6 pg Se mL-1 and 2.8% relative standard deviation (RSD) (with 1 ng mL-1 Se, n=11), and 12% RSD (with 0.05 ng mL-1 Se, n=7) were obtained by this enrichment technique and AFS detection.
Fluorescence Speciation

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

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

"Optimization Of Selenium Determination In Vegetables, Fruits, And Dairy Products By Flow Injection Hydride Generation Atomic Absorption Spectrometry"
Chem. Pap. 2003 Volume 57, Issue 3 Pages 155-157
M. Kore&#328;ovsk&aacute;

Abstract: A flow injection hydride generation atomic absorption spectrometric (FI-HG-AAS) method was developed for determination of selenium in vegetables, fruits, and dairy products after microwave digestion of samples. The experimental conditions for FIAS 400 (concentration of reducing agent and carrier acid, time of reduction, flow rate of argon carrier gas) were optimized. The linearity range under optimized conditions was 0.20-25.0 ?g dm -3.The detection limit of the proposed method was 0.06 ?g kg -1 and limit of quantitation was 0.20 ?g kg-1. The procedure was validated by the method of standard additions (5.0 ?g dm -3 and 10.0 ?g L-1 in vegetables, fruits, and dairy products) and the recoveries were from 88% to 104%. The accuracy was evaluated using BCR 150 skin milk reference material (found: 0.128 mg kg-1, Sx = 0.004 mg kg-1, certified: 0.132 mg kg-1, Sx = 0.010 mg kg-1). The combined standard uncertainty of selenium was 8.4%. The method was developed and used for determination of selenium in vegetables, fruits, and dairy products consumed in Slovakia.
BCR 150 Vegetable Fruit Dairy Products