In the present work, a sample pre-treatment technique for the determination of trace concentrations of benzene, toluene, ethyl ben- zene and xylene (BTEX) in aqueous samples has been developed and applied to analysis of the selected analytes in environmental water samples. The extraction procedure is based on coupling polypropylene hollow-fiber liquid phase microextraction (HF-LPME) with gas chromatography by flame ionization detection (GC-FID). The effective parameters such as organic solvent, extraction time, agitation speed and salting effect were investigated. Good reproducibilities of the extraction performance were obtained, with the RSD values ranging from 2.02 to 4.61% (n = 5). The method provided 41.47–128.01 fold preconcentration of the target analytes. The limits of detec- tions for the BTEX were in the range of 0.005–03 lgml 1 . In addition, sample clean-up was achieved during LPME due to the selectivity of the hollow fiber, which prevented undesirable large molecules from being extracted. Real samples (River and waste waters) containing BTEX were examined using this method with good linearity and precision (RSDs most lower than 6.00%, n=5). All experiments were carried out at room temperature, 22 ± 0.5 C.  2007 Elsevier Ltd. All rights reserved.

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