Determination of benzene, toluene, ethylbenzene and xylenes in indoor air at environmental levels using diffusive samplers in combination with headspace solid-phase microextraction and high-resolution gas chromatography-flame ionization detection

An improved analytical method for passive air sampling is presented based o n a combination of commercially available diffusive samplers with headspace solid-phase microextraction and high-resolution gas chromatography with fl ame ionization detection (HRGC-FID). This procedure is targeted for short-t erm BTEX (benzene, toluene, ethylbenzene and o-, m- and p-xylenes) determin ations at environmental concentrations and can be applied for sampling inte rvals between 30 min and 24 h. The analytes are adsorbed onto the charcoal pad of a passive sampler and then extracted with carbon disulphide-methanol . After removal of the carbon disulphide by xanthation, the BTEXs are enric hed on a Carboxen SPME fiber, thermally desorbed and analysed by HRGC-FID. Detection limits for a sampling interval of 2 h are between 0.4 and 2 mu g/ m(3), within-series precision ranges between 6.6 and 12.8%, day-to-day prec ision is between 11.1 and 15.2%. The results obtained with this procedure a re validated by comparison with active sampling. Detection limits and a fur ther reduction of the sampling time are limited by blanks of the chemicals and the diffusive samplers. Procedures to eliminate these blanks are descri bed in detail. Applications such as the determination of BTEXs in indoor ai r inside buildings, inside a train and a car are presented, indicating the usefulness of the described procedure for short-term measurements of enviro nmental BTEX concentrations. An advantage of passive samplers is the storag e stability for at least six months, which is essential for its use in larg e epidemiological studies. (C) 1998 Elsevier Science B.V. All rights reserv ed.