ANALYSIS OF VOCS IN AIR BY AUTOMATED TUBE SAMPLING AND THERMAL-DESORPTION GC-MS

An analytical method has been investigated for the efficient simultane ous determination of toxic volatile organic compounds (VOCs) in ambien t air. The adsorption by the sorbent followed by thermal desorption wa s optimized for the various concerned parameters such as the selection of sorbent and the breakthrough volume to each compound as well as te mperature, flow and time for the focusing trap, before the introductio n 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 th e breakthrough volume at 20 degrees C and the recovery of 92-107% unde r 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 th e real sample of air collected at the several locations of town and ru ral area over 24 hours, and also at the fence line of chemical works.