Benefits and Limitations of Static Headspace and Purge-and-Trap for the Analysis of VOCs

Static headspace analysis can provide reasonably good sensitivity for halogenated hydrocarbons and aromatic compounds. But USEPA Method 524.2 Revision 4 requires the evaluation of several analytes containing different functional groups such as ketones, ethers, and esters. Such compounds can be particularly difficult to analyze at low concentration using static headspace due to the affinity of polar analytes for the aqueous sample matrix. The same problem can occur with purge-and-trap, but the technique of dynamic extraction allows greater sensitivity over a static equilibrium process. In this paper, static headspace sampling is compared with purge-and-trap for the gas chromatographic (GC) analysis of the USEPA Method 524.2 Rev. 4 target compounds.