Analysis of VOCs in air by automated tube sampling and thermal desorption GC-MS

Abstract

An analytical method has been investigated for the efficient simultaneous determination of toxic volatile organic compounds (VOCs) in ambient air. The adsorption by the sorbent followed by thermal desorption was optimized for the various concerned parameters such as the selection of sorbent and the breakthrough volume to each compound as well as temperature, flow and time for the focusing trap, before the introduction of analytes to GC-MS. It was found that the multiple-bed packing of sorbents of Carbopack B and Carboxene 1000 allowed more than 60L of the breakthrough volume at 20°C and the recovery of 92-107% under the optimized conditions. The practical use of this method with the quantitation limit of 0.01-0.05 ppbv for 10L air sample was validated for the standard sample of VOCs. Finally, the method was applied to the real sample of air collected at the several locations of town and rural area over 24 hours, and also at the fence line of chemical works.