Determination of benzene, toluene, ethylbenzene, xylenes in water at sub-ng 1~(-1) levels by solid-phase microextraction coupled to cryo-trap gas chromatography-mass spectrometry

摘要

A trace analytical method of benzene, toluene, ethylbenzene and xylenes (BTEX) in water has been developed by using headspace solid-phase microextraction (HS-SPME) coupled to cryo-trap gas chromatography-mass spectrometry (GC-MS). The chromatographic peak shape for BTEX was improved by using cryo-trap equipment. The HS-SPME experimental procedures to extract BTEX from water were optimized with a 75 μm carboxen/polydimethylsiloxane (CAR/PDMS)-coated fiber at a sodium chloride concentration of 267 g 1~(-1), extraction for 15 min at 25 ℃ and desorption at 290 ℃ for 2 min. Good linearity was verified in a range of 0.0001-50 μg 1~(-1) for each analyte (r~2 = 0.996-0.999). The limits of detection (LODs) of BTEX in water reached at sub-ng 1~(-1) levels. LODs of benzene, toluene, ethylbenzene, w/p-xylene and o-xylene were 0.04, 0.02, 0.05, 0.01 and 0.02 ng 1~(-1), respectively. The proposed analytical method was successfully used for the quantification of trace BTEX in ground water. The results indicate that HS-SPME coupled to cryo-trap GC-MS is an effective tool for analysis of BTEX in water samples at the sub-ng 1~(-1) level.