Solid-Phase Microextraction

Solid-phase microextraction (SPME) is an attractive method for isolating an analyte prior to injecting it into a gas chromatograph. In one approach, which is illustrated here, a fused-silica fiber is placed inside a syringe needle. The fiber, which is coated with a thin film of an adsorbent, such as polydimethyl siloxane, is lowered into the sample by depressing a plunger and is exposed to the sample for a predetermined time. After withdrawing the fiber into the needle, it is transferred to the gas chromatograph for analysis.