Assessing air quality inside vehicles and at filling stations by monitoring benzene, toluene, ethylbenzene and xylenes with the use of semipermeable devices

Abstract

BTEX (benzene, toluene, ethylbenzene, and xylenes) were used as target molecules to evaluate the quality of air inside motor vehicles and near filling stations, using semipermeable membrane devices (SPMDs) as low-cost passive sampling devices. A direct, fast, simple methodology based on the use of headspace-gas chromatography-mass spectrometry detection (HS-GC-MS) was developed for BTEX determinations, without any sample pre-treatment. SPMDs (25.4 cm2 surface, filled with 100 microL triolein) were employed as static samplers. After the selected deployment time, the SPMDs were heated inside a HS vial at 150 degrees C for 20 min and BTEX compounds were determined by GC-MS in selected ion monitoring (SIM) mode in less than 12 min. The proposed method provides limits of detection of less than 1 ng SPMD(-1) for all compounds studied; which is equivalent to 0.3-8 ng m(-3) in air for a deployment time of 24 h, and to 9-200 microg m(-3) for 10 min time, as a function of the compound considered. Using sampling times of around 24 h, concentrations from 0.2 to 145 microg m(-3) were measured inside motor vehicles. For exposure times from 2 to 40 min, concentrations of BTEX ranging from 0.03 to 79 mg m(-3) were measured at filling stations, especially during refueling of vehicles with gasoline.