2RONG LEEM, M IN CHANG C, DOU J. Determination of benzene, toluene, ethylbenzene, xylenes in water at sub-ngL - I lev- els by solid-phase microextraction coupled to cryotrap gas chro-matography-mass spectrometry [ J ]. Chem Osphere, 2007,69 (1) :1381-1387.
3HERRADOR E A, LUCENA R, C'ARDENAS S, et al. Ionic liquid-based single-drop micro extraction/gas chromatographic / mass spectrometric determination of benzene, toluene, ethy| benzene and xylene isomers in waters[ J]. J Chromat A, 2008, 1201(1) :106-111.
4CARR I'ON C C, LUCENA R, C'ARDENAS S, et al. Liquid-liquid extraction/headspace/gas chromatographic/mass spec- trometric determination of benzene, toluene, ethylbenzene, ( o-, m- and p-) xylene and styrene in olive oil using surfactant- coated carbon nanotubes as extractantr J] . J Chrom at A. 2007.1171(1-2) :1-7.