Headspace analysis is a technique for sampling and examining the volatiles in a solid or liquid sample. The term headspace refers to the volume of vapor above a condensed phase sample. Purge and trap refers to the headspace technique in which volatile organic compounds (VOCs) are purged out of the sample matrix by an inert gas and carried onto a sorbent trap, where they are concentrated and later introduced into an instrument (e.g., 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. Low volatility solutes can also be collected and concentrated using purge and trap. The instrumentation and procedures are slightly different for liquid and solid samples, and the analyte of interest. This article discusses its basic theory, instrumentation, operational procedures, quantification methods, and selected applications.
Encyclopedia of Analytical Science
Chemical analysis, headspace, purge and trap, vapor