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  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 1087-1093 
    ISSN: 1040-0397
    Schlagwort(e): Selenium ; Stripping voltammetry ; Medium exchange ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An adsorptive cathodic stripping voltammetric method for the determination of Se(IV) is described. The method is based on the detection of the piazselenol complex formed by Se(IV) with 2,3-diamino naphthalene (2,3 DAN) at pH 2 (0.01 mol L-1 HC1 + 0.1 mol L-1 KC1). The method is based on a medium-exchange scheme and a carbon paste electrode (CPE). The preconcentration step is carried out at open circuit, and then the complex is stripped out by linear sweep voltammetry (LSV) after medium exchange (0.1 mol L-1 HNO2 + 0.1 mol L-1 KNO3 where the working electrode is transferred). The method is characterized by a precision better than 8% and a limit of quantitation (10 times the standard deviation of the blank) of 1.25 × 10-7 mol L-1 (for 20 minutes of preconcentration time). The use of CPE coupled with the medium-exchange scheme reduces the interferences (especially by different classes of surfactants) and improves the selectivity (much better than in the usual cathodic stripping voltammetry on mercury).
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    ISSN: 0268-2605
    Schlagwort(e): Organotin ; identification ; mixed methylbutyl forms ; monophenyltin ; crosscomparison ; mis-interpretation ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Biogeochemical pathways of tin species in the environment are still controversial, e.g. with regard to methylation and transmethylation phenomena, owing to the fact that the identification of methylated tin-compounds is often difficult. The previous tentative identification of a mixed methylbutyltin compound in sediment and biological samples by GC/AAS after hydride generation gave an illustration of this problem. This compound was previously identified in sediments by other authors and also suspected to occur in a contaminated sediment sample from the Boyardville Marina, France. The retention time obtained by GC/AAS corresponded to the actual retention time of a mixed methylbutyltin calibrant. However, additional checks demonstrated that the compound detected was actually monophenyltin. This evidence was produced by a thorough analysis of a selected sediment sample by alternative techniques such as GC/AAS and GC/AES after pentylation, GC/FPD and GC/MS. The results presented highlight the need for a full identification of compounds to avoid mis-interpretation.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 563-570 
    ISSN: 0268-2605
    Schlagwort(e): Methylmercury ; human hair ; capillary GC-electron capture detection ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An analytical procedure was developed for the determination of methylmercury in human hair using capillary gas chromatography with electron capture detection (GC-ECD). Hair samples are digested in alkaline solution/toluene in an ultrasonic bath at about 50°C. After cooling and treatment with hydrochloric acid (6 mol I-1) and a saturated solution of copper sulphate, the organic phase is extracted with a cysteine solution. Methylmercury is back-extracted in toluene by adding copper sulphate and potassium bromide and analysed by GC-ECD using a DB17 capillary column. The practical detection limit of the method for methylmercury is 50 ng g-1 using 100 mg of hair sample. Column performances and injection reproducibility have been evaluated. Results on 13 samples of human hair are presented and related to the total mercury concentration. The method, consisting of the optimization of similar analytical procedures through improvements in the various steps, allows for sensitive and reliable quantitation of methylmercury in hair with good precision and accuracy.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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