Air enrichment Environmental samples Natural gas

A new method for the preconcentration of trace components from gaseous samples is described. The system is based on enrichment of the solutes on a packed bed of 100 % polydimethylsiloxane (PDMS) particles followed by thermal desorption and GC analysis. It was demonstrated that breakthrough volumes for packed PDMS traps can be calculated from theoretical equations. The PDMS material exhibits excellent thermal stability even after 200 consecutive runs. Additional advantages of packed sorbent beds over conventional adsorbent materials include high inertness, the absence of displace-ment effects and a reduced affinity for water. The practicality of the system was demonstrated by the analysis of air and natural gas. Using the system described here, components in the range of octane to benzo[a]pyrene could be quantitatively trapped and thermally desorbed at mild temperatures. With the present set-up the detec-tion limit is in the order of 0.1 ng/m3 (MSD detector).