Grab sampling for the determination of sulfur dioxide and dimethyl sulfide in air by isotope dilution gas chromatography/mass spectrometry |
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Authors: | Byron W Blomquist Alan R Bandy Donald C Thornton Shaoming Chen |
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Institution: | (1) Department of Chemistry, Drexel University, 19104 Philadelphia, PA, USA |
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Abstract: | Developments allowing the direct determination of sulfur dioxide and dimethyl sulfide in grab samples by gas chromatography/mass spectrometry with isotopically labeled standards (GC/MS/ILS) are reported. Isotopomers of DMS and SO2 are used as internal standards. Spiked air samples are dried to a dew point of <–60 °C and trapped cryogenically in loops of Teflon tubing. Sealed samples are transported to the laboratory under liquid nitrogen and later subjected to GC/MS analysis. Holding times of up to one month do not result in significant sample loss. For samples collected in a clean marine environment, concentrations of SO2 and DMS greater than 5 and 8 pptv, respectively, are significantly different from blanks at the 95% confidence level. Average measurement precision derived from a propagation of errors are 9% for SO2 and 42% for DMS at concentrations from 5–15 pptv.Improvements are outlined which should provide sensitivity and precision comparable to that of on-site GC/MS. The technique will allow increased flexibility for the determination of trace sulfur species in the field under conditions where deployment of a mass spectrometer is not possible. |
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Keywords: | Dimethyl sulfide sulfur dioxide isotope dilution gas chromatography mass spectrometry grab sampling |
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