Analysis of volatile organic compounds in water and soil samples by purge and membrane mass spectrometry

A new method, purge-and-membrane mass spectrometry (PAM MS), is introduced for the analysis of volatile organic compounds (VOCs) in water and soil samples, In this method, VOCs are purged from water or soil samples with an inert gas and the stream is directed through a sheet membrane module. The VOCs pervaporate through the membrane directly into the ion source of a mass spectrometer. The limits of detection for nonpolar VOCs such as halogenated hydrocarbons, benzene, toluene, and xylenes were below micrograms per liter in water samples and at low micrograms per kilogram levels in soil samples. The correlation coefficients measured for the compounds studied were typically better than 0.9999 and 0.9975 in water and soil samples, respectively. The relative standard deviations were between 0.5 and 2.0% with water samples and between 4.8 and 14.0% with soil samples. These results demonstrate excellent linearity and repeatability. PAM MS thus provides a highly sensitive, selective, accurate, solvent-free, and rapid analytical method. Tens of samples can be analyzed reliably within 1 h.