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Determination of Compound-Specific Carbon Isotope Ratios of Chlorinated Methanes, Ethanes, and Ethenes in Aqueous Samples
Auteur(s)
Date de parution
2000
In
Environmental Science & Technology, American Chemical Society, 2000/34/13/2839-2844
Résumé
Compound-specific carbon isotope ratio analysis is a promising tool to assess the origin and fate of organic contaminants in groundwater. The aim of this study was to develop and evaluate a reliable, fast method to determine carbon isotope ratios of chlorinated methanes, ethanes, and ethenes in aqueous samples. Direct solid-phase microextraction (dSPME) and headspace solid-phase microextraction (hSPME) were selected as extraction method and compared to headspace equilibration. For dSPME and hSPME, deviations between carbon isotope ratios in the aqueous phase and on the SPME fiber were e 0.40‰. For headspace equilibration, molecules in the gas phase were enriched in <sup>13</sup>C compared to molecules in the aqueous phase by up to 1.46‰, in particular for chlorinated methanes. The absence of significant carbon isotope fractionation during dSPME and hSPME could be explained by the fact that both the aqueous phase and the SPME fiber coating discriminate against molecules with <sup>13</sup>C to a similar degree, and thus no net carbon isotope fractionation occurs. If aqueous phase/gas-phase carbon isotope fractionation during headspace equilibration is taken into account, all methods, dSPME, hSPME, and headspace equilibration, provide accurate δ<sup>13</sup>C values with a similar precision. Direct SPME was the most sensitive method with detection limits as low as 130 ppb.
Identifiants
Type de publication
journal article
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