Calibration procedure for solid phase microextraction-gas chromatographic analysis of organic vapours in air

A calibration procedure for solid phase microextraction-gas chromatographic (SPME-GC) analysis of organic vapours in air was described in which GC detector (MS in this case) signal is directly related to concentration of analytes of interest sampled by SPME. Gaseous standard mixtures used for the calibration were generated by means of a home-made permeation-type apparatus described elsewhere, W. Janicki et al., Chem. Anal., 38 (1993) 423 and modified to permit easy sampling of analytes on an SPME fibre. To establish sampling parameters, times for equilibrium partitioning of five selected organic compounds (carbon tetrachloride, toluene, chlorobenzene, p-xylene, n-decane) between gaseous mixtures and the fibre (fused silica fibre coated with 100 mum polydimethylsiloxane) were determined. For 10 min sampling time, the detector response and hence amount sampled on the fibre were linear functions of analytes concentration in a gaseous sample.