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刘维屏

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期刊论文

Determination of Enantiomers of Synthetic Pyrethroids in Water by Solid Phase Microextraction - Enantioselective Gas Chromatography

刘维屏WEIPING LIU AND JAY J. GAN*

J. Agric. Food Chem. 2004, 52, 736-741,-0001,():

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摘要/描述

Solid phase microextraction (SPME) is an ideal sample preparation technique because of its speed and solvent-free features. Sampling by SPME is selective and only the dissolved concentration is measured, which allows measurement of the bioavailable fraction of a contaminant in aqueous media. One potential application of SPME is for analysis of enantiomers of chiral contaminants in environmental samples. In this study, a method was developed for determining enantiomers of (Z)-cis-bifenthrin and cis-permethrin in water using coupled SPME and enantioselective gas chromatography (GC). Following SPME sampling, enantiomers of (Z)-cis-bifenthrin and cis-permethrin were separated at the baseline on a â-cyclodextrin-based enantioselective column, and analyte enrichment onto the SPME fiber was not enantioselective. The GC response increased as sampling time was increased from 0 to 240 min, and as sampling temperature was increased from 20 to 40℃. Organic solvents such as methanol, acetone, and acetonitrile enhanced, while soil extracts slightly decreased, the GC response. The integrated SPME-enantioselective GC method was used to analyze surface runoff samples. The analysis showed preferential degradation of the 1S-3S enantiomer over the 1R-3R enantiomer for both (Z)-cis-bifenthrin and cis-permethrin. The concentrations detected by SPMEGC were substantially smaller than those determined following solvent extraction, suggesting that SPME-enantioselective GC analysis selectively measured the dissolved fraction.

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