Evaluating BTEX in vehicle exhaust gas: A fast and efficient approach using SPME and GC-BID

Abstract

Benzene, toluene, ethylbenzene, and the xylene isomers (m, p, and o-xylene) (BTEX) are known for their harmful effects on human health and have been extensively studied across various environmental matrices. However, quantifying BTEX in exhaust gases poses challenges due to the complexity of the matrices. In this study, we investigated a method development strategy involving solid-phase microextraction (SPME) and gas chromatography coupled with a dielectric barrier discharge ionization Detector (BID) for quantifying BTEX emitted from internal combustion engines operating at idle. Sampling was conducted using 1.0 L Tedlar bags, followed by withdrawal of aliquots and dilution with atmospheric air using a novel device (graduated vial) designed for gaseous samples. The SPME-GC-BID method was developed and validated for the conditions: BTEX extraction in CAR/PDMS 75 μm fiber at a contact time of 5.0 min at a temperature of 27 °C, followed by GC-BID analysis. Method validation to ensure the reliability of quantitative results used the merit figures e.g., limits of detection (LOD) and quantification (LOQ), precision, and accuracy (recovery). LOD varied from 0.194 to 0.340 mg m^-3, LOQ varied from 0.587 to 1.03 mg m^-3, precision ranged from 1.47 to 7.14 %, and recovery varied from 82.34 to 109.5 %. BTEX concentration in vehicle exhaust varied from 3.40 to 16.4 mg m^-3. The results showed, concerning the figures of merit analyzed, that the SPME-GC-BID method provides good sensibility, precision, and accuracy for evaluating the presence of BTEX in the exhaust of internal combustion engines, contributing to the understanding of health risks associated with vehicle emissions.

Keywords: Barrier ionization discharge detector; Monoaromatic hydrocarbons; SPME sampling; Vehicle emission; exhaust gas analysis.