High-Speed Isothermal Analysis of Atmospheric Isoprene and DMS Using On-Line Two-Dimensional Gas Chromatography
An instrument has been developed that allows rapid measurements of two of the most important volatile organic species in the atmosphere. The method utilizes two-dimensional gas chromatography coupled to a programmed temperature vaporization injector used for sample preconcentration and injection. Attention is paid to the deter mination of atmospheric concentrations of isoprene (the most reactive hydrocarbon species) and dimethyl sulfide (DMS), the major source of sulfur in the marine troposphere and a precursor to cloud formation. A sorbent packed liner placed inside a programmed temperature vaporization injector was held subambiently by means of a Peltier device during sample collection. Thermal desorption is performed and the analytes passed to a primary column, separating with respect to analyte vapor pressure. Selected linear or “heart-cut” transfer is performed to a second column where the final separation is performed with respect to chemical functionality. Both primary and secondary separa tions ar...