Membrane introduction system for trace analysis of volatile organic compounds using a single photon ionization time-of-flight mass spectrometer

A silicone membrane sample introduction system combined with a vacuum ultraviolet single photon ionization time-of-flight mass spectrometer (VUV-SPI-TOFMS) has been developed to detect trace volatile organic compounds in environmental air. The maximum enrichment factors of benzene. toluene, and chlorobenzene using the membrane introduction system relative to a direct introduction system were found to be 15.3, 11.0, and 12 1, respectively. The gas permeability of toluene through the silicone membrane was consistent with that of the manufacturer's reported value. The gas permeabilities of the silicone membrane used in the present study were estimated for benzene and chlor benzene by theoretical calculations using the enrichment factors. The enrichment factors of benzene, toluene, and chlorobenzene were independent of their mixing ratios at <34 ppmv. The detection limits of benzene and chlorobenzene with the membrane introduction system were improved by one order of magnitude relative to direct introduction. Detection of almost sub-ppbv level of benzene and chlorobenzene was achieved in the membrane introduction VUV-SPI-TOFMS. (C) 2010 Elsevier B V All rights reserved