Purge and Trap

Purge and trap refers to the technique in which volatile organic compounds (VOCs) are purged out of the sample matrix by an inert gas and carried on to a sorbent trap, where they are concentrated and later introduced into an instrument (gas chromatography (GC) or GC/mass spectrometry (MS)) for analysis. After its introduction in the 1970s, purge and trap quickly gained widespread acceptance, and was adopted by regulatory agencies as a standard method. Today, it is still the workhorse for the analysis of low-concentration VOCs in solids and liquids. The instrumentation and procedures are slightly different for liquid and solid samples. This article discusses its basic theory, instrumentation, operational procedures, quantification methods, and selected applications.