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  • 1
    ISSN: 1618-2650
    Keywords: Best. von Bleitetraalkyl in Luft ; Spektrometrie, Atomabsorption ; Graphitofen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The determination of the total concentration of tetraalkyllead compounds in the air is based on the cryogenic condensation in a cooled trap at −130° C, thermal desorption at 60° C into impingers containing nitric acid and hydrogen peroxide and a determination with graphite furnace atomic-absorption. The method is highly specific and suffers no interferences from lead in the particulate phase. The detection limit is 42 ng Pb/m3 for air samples of ca. 3601.
    Notes: Zusammenfassung Die Bestimmung der Gesamtkonzentration an Tetraalkylbleiverbindungen in der Luft beruht auf der Kondensation in einer Kühlfalle bei −130° C, Desorption bei 60° C in ein Salpetersäure-Wasserstoffperoxid-Gemisch und anschließender Bestimmung mit Graphitofen-AAS. Die Methode ist hochspezifisch und wird durch bleihaltige Festteilchen nicht gestört. Die Nachweisgrenze beträgt 42 ng Pb/m3 für 3601-Proben.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0268-2605
    Keywords: Natural environment ; methylated selenium species ; environmental samples ; ground soil ; smelter ; murine exhalation ; selenium metabolite ; flash-like injection ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A systematic study of the biomethylation of selenium and the determination of the methylated species indicates preliminarily that selenium is susceptible to natural biomethylation under certain environmental conditions. Detectable levels of methylated selenium species, including dimethyl selenide [(CH3)2Se], dimethyl diselenide [(CH3)2Se2] and dimethylselenone [(CH3)2SeO2] have been detected by gas chromatography - graphite furnace atomic absorption spectrophotometry (GC - GF AA) from a variety of environmental samples. Findings of naturally methylated selenium species from both soil samples and related air samples suggest that there may exist a localized cycle of selenium between ground soil and the ambient air.Factors that influence the sensitivity and accuracy for the determination of alkyl selenide compounds by GC - GF AA have also been investigated. Flashlike injection mode and addition of about 10% of hydrogen gas to the argon carrier gas provide for highly sensitive detection. Reproducible determination can be obtained with a precision of about 6% and the detection limits are 0.3 ng Se m-3.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
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