Determination of polydimethylsiloxane脙脙脙脙脙脙seawater distribution coefficients for polychlorinated biphenyls and chlorinated pesticides by solid-phase microextraction and gas chromatography脙脙脙

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• 作者：Zeng ; Eddy Y. ; Tsukada ; David ; Noblet ; James A. ; Peng ; Jian
• 关键词：Solid-phase microextraction ; Partition coefficient ; Hydrophobic organic compound ; Calibration
• 刊名：Journal of Chromatography A
• 出版年：2005
• 期刊代码：47_00219673
• 类别：ch
• 出版时间：February 25, 2005
• 卷：1066
• 期：1-2
• 页码：165-175
• 文件大小：179 K

摘要

Applications of solid-phase microextraction (SPME) in the measurement of very hydrophobic organic compounds (VHOCs) are limited, partly due to the difficulty of calibrating SPME fibers for VHOCs. This study used a static SPME strategy with a large sample volume (1.6 L) and a five-point calibration procedure to determine the distribution coefficients for a large suite of polychlorinated biphenyls (PCBs) and chlorinated pesticides between a polydimethylsiloxane (PDMS) phase (100 μm thickness) coated on a glass fiber and seawater. An extraction time of 12 days was deemed adequate for equilibrium calibration from kinetic experiments. Two groups of randomly selected fibers divided into three batches (up to nine fibers in each batch) were processed separately with two gas chromatography–mass spectrometry (GC–MS) systems. Matrix effects arising from losses of the analytes to glass container walls and stirring bars were corrected. Relative standard deviations within the same batch were generally smaller than those for the entire group. Furthermore, K_fV_f (K_f and V_f are the distribution coefficient of an analyte between the polymer-coated fiber and aqueous phase and the fiber volume, respectively) values determined with two GC–MS systems were statistically different. These results indicate the calibrated K_fV_f values were less affected by the random selection of SPME fibers than by other experimental conditions, and therefore average K_fV_f values may be used for the same type of commercially available SPME fibers. The relative accuracy of our calibration method was similar to that of a previous study [P. Mayer, W.H.J. Vaes, J.L.M. Hermens, Anal. Chem. 72 (2000) 459] employing different coating thickness and calibration procedure. The present study also obtained a bell-shaped relationship between log K_f and log K_ow (octanol–water partition coefficient) for PCB congeners with the maximum log K_f corresponding to log K_ow  6.5. This bell-shaped relationship was attributed mainly to steric effects arising from the interplay between the PDMS thickness and molecular sizes of the target analytes.