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  • 1
    Electronic Resource
    Electronic Resource
    Interference of humic substances on the speciation analysis of inorganic selenium in waters and soils by DPCSV (1995)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 351 (1995), S. 443-448 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A speciation scheme allowing the study of selenium speciation in environmental samples has been developed in order to study the transfer mechanism in the system water/soil/plant/animal. This scheme is based on a set of sample treatment procedures followed by Se(IV) determination by Differential Pulse Cathodic Stripping Voltammetry (DPCSV). Se(IV) may be determined with a detection limit close to 25 ng l−1 and a linear response in the range 25–4000 ng l−1. However, humic substances, present in some natural waters and soils, which are adsorbed at the mercury drop electrode (HMDE) surface may alter the signal. This may be caused by a competition between adsorption of organic matter and mercury(II) selenide formation at the electrode surface. As a consequence the detection limit has been increased to ca. 250 ng l−1 in the presence of 1 mg l−1 fulvic acids; the linear response range is then shifted to 250–10000 ng l−1. After an extensive study of these interferences and using standard additions procedures, the Se(IV) content of various waters and soil extracts has been determined by DPCSV with a good reproducibility (RSD about 1%). Accuracy is satisfactory comparing the results obtained by DPCSV to those obtained by Hydride Generation/Quartz Furnace Absorption Atomic Spectrometry (HG/QFAAS).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00322916
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  • 2
    Electronic Resource
    Electronic Resource
    Analytical methods for the speciation of selenium compounds: a review (1994)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 348 (1994), S. 792-805 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Selenium, like sulphur, exists in the environment in several oxidation states and as a variety of inorganic and organic compounds. Dissolved inorganic selenium can be found in natural waters as selenide Se (−II), as colloidal elemental selenium Se (0), as selenite anions HSeO 3 − and SeO 3 2− i.e. Se (+IV) and as the selenate anion (SeO 4 2− ) i.e. Se (+VI). Organic forms of selenium that may be found in organisms, air or in the aqueous environment, are volatile (methylselenides) or non volatile (trimethylselenonium ion, selenoamino acids and their derivatives). Knowledge of the different chemical forms and their environmental and biomedical distribution is important because of the dependence of bioavailability and toxicity on speciation. This paper reviews the different analytical methods used for the speciation of selenium compounds, with special attention to inorganic selenium and organoselenium species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01780980
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Selenoamino acid speciation using HPLC-ETAAS following an enzymic hydrolysis of selenoprotein (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 9 (1995), S. 623-628 
    Details
    ISSN: 0268-2605
    Keywords: analysis ; speciation ; HPLC-ETAAS ; enzymic extraction ; selenoamino acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A high-pressure liquid chromatography-electrothermal atomic absorption spectroscopy (HPLCETAAS) hyphenated technique was used for the determination of seleno compounds present in a selenium-enriched yeast. Conditions were optimized for the separation and quantification of the selenoamino acids, selenocystine and selenomethionine, in the presence of other compounds. The separation was achieved by ion-pairing chromatography using sodium heptanesulphonate as the anionic counterion. On-line detection was carried out using electrothermal atomic absorption with palladium(II) as a matrix modifier. Different extraction procedures were tested on a seleniumenriched yeast. A 92% recovery of the total selenium present in the material was obtained. Attempts to evaluate selenium speciation were carried out; selenomethionine and selenocystine were identified as the major components (42% and 35% respectively).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590090718
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  • 4
    Electronic Resource
    Electronic Resource
    Speciation of butyltin compounds by on-line HPLC-ETAA of tropolone complexes in environmental samples (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 6 (1992), S. 39-47 
    Details
    ISSN: 0268-2605
    Keywords: Butyltin ; HPLC-ETAA ; tropolone complexes ; water ; sediment ; environment ; speciation ; determination ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tropolone (Trop) forms in solution stable complexes with monobutyltin (MBT Trop2) and dibutyltin (DBT Trop). This property has been used to develop a separation procedure of butyltin compounds by liquid chromatography on cyanopropyl-bonded silica columns with a solution of tropolone in toluene as eluent.Tin-specific detection by on-line ETAA allowed the development of a simple procedure suitable for the determination of tributyltin and dibutyltin in water and sediment samples.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590060106
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  • 5
    Electronic Resource
    Electronic Resource
    Speciation of butyltin compounds by ion chromatography coupled to electrothermal atomic absorption spectrometry (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 7 (1993), S. 213-218 
    Details
    ISSN: 0268-2605
    Keywords: Butyltin ; ion chromatography ; speciation ; electrothermal atomic absorption spectrometry (ETAAS) ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method for the determination of butyltin species by ion-exchange chromatography linked with graphite-furnace electrothermal atomic absorption spectrometry (ETAAS) is presented. The separation is achieved on a strong cation-exchange column with a 0.18 mol dm-3 solution of diammonium citrate at pH 6.5 with a step change to pH 4.0 in 60:40 methanol/water solvent. ETAAS detection is performed on-line using an oxidizing matrix modifier. Mono-, di- and tri-butyltin may be determined in a single experiment with detection limits of (respectively) 0.5, 1.1 and 0.8 ng (Sn). Applications to actual samples are reported.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590070309
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Speciation of selenoamino acids by on-line HPLC ETAA spectrometry (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 7 (1993), S. 593-598 
    Details
    ISSN: 0268-2605
    Keywords: Selenoamino acids ; HPLC ETAAS ; speciation ; environment ; determination ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analytical method was developed to determine selenoamino acids in the presence of other compounds. Separation has been achieved by High Performance Liquid Chromatography (HPLC) using electrothermal atomic absorption (ETAA) spectrometry as a very sensitive and element-specific detector. On-line HPLC ETAAS speciation of selenocystine and selenomethionine has been studied, using a laboratory made interface. Analytical characterization of the method has been realized with standard solutions. Using a 100μl sample loop, the detection limits were calculated as 8 μgl-1 for selenomethionine and 10 μgl-1 for selenocystine with repeatability and reproducibility of 4% and 7% respectively. The method has been applied to the determination of selenoamino acids in an extract of white clover (CRM402) certified for total selenium.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590070720
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