A NEW METHOD FOR SORPTIVE ENRICHMENT OF GASEOUS SAMPLES - APPLICATIONIN AIR ANALYSIS AND NATURAL-GAS CHARACTERIZATION

A new method for the preconcentration of trace components from gaseous samples is described. The system is based on enrichment of the solute s on a packed bed of 100% polydimethylsiloxane (PDMS) particles follow ed by thermal desorption and GC analysis. It was demonstrated that bre akthrough volumes for packed PDMS traps can be calculated from theoret ical equations. The PDMS material exhibits excellent thermal stability even after 200 consecutive runs. Additional advantages of packed sorb ent beds over conventional adsorbent materials include high inertness, the absence of displacement effects and a reduced affinity for water. The practicality of the system was demonstrated by the analysis of ai r 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 d etection limit is in the order of 0.1 ng/m(3) (MSD detector).