| Solid-phase microextraction (SPME) as a new sample pretreatment technology have been developed rapidly in recent years since it possesses several attractive features including simple operation, small sample volume, solventless extraction, and high sensitivity. Monolithic column have been used widely in solid phase microextraction fields because of the advantages of simple preparation, good permeability, high spicific surface characteristics, low mobile phase and sample consumption, little pollution, easy integration with other detectors.In this study, two different diameter specifications of monolithic column with 100μm and 530μm was prepared by in-situ free radical polymerization of stearyl methacrylate (SMA) with ethylene glycol dimethacrylate (EDMA) using the porogens composing of iso-amyl alcohol and 1,4-butanediol in the presence of the initiator AIBN.One was entrapped with silica microparticles , and the other without. The prepared monolithic columns were used as the extraction column for sample of enrichment and sample introductin to micro-HPLC. The extraction conditions were optimized experimentally in detail. and the enrichment factors of the microextraction columns were determined under the optimal conditions . It was demonstrated that the obtained enrichment factor using the silica-particle-entrapped microextraction column of larger diameter was obviously higher than using the columns with no entrapped silica particles and the columns of smaller inner diameters. When the silica-particle-entrapped microextraction column of larger diameter was used for sample enrichment and injection to micro-HPLC, the detection limits (equivalent to noise signal standard deviation of 3 times) were determined to be 3.71μg/L, 1.64μg/L and 2.52μg/L for benzene, toluene, and butylbenzene, respectively. The method presented in this study has a good potential to be applied for the determination of trace benzenes in waters. |
