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Stereoselective Degradation Kinetics of Theta-Cypermethrin in Rats

2006; American Chemical Society; Volume: 40; Issue: 3 Linguagem: Inglês

10.1021/es052025+

1520-5851

Qiuxia Wang, Jing Qiu, Wentao Zhu, Guifang Jia, Junling Li, Chenglu Bi, Zhiqiang Zhou,

Pesticide Residue Analysis and Safety

The enantioselective degradation and chiral conversion of theta-cypermethrin (TCYM) in rats have been studied via intravenous (i.v.) injection. The degradation kinetics and the enantiomer fraction (EF) were determined by means of normal-phase high-performance liquid chromatography (HPLC) with diode array detection (DAD) and a cellulosetris-(3,5-dimethylphenylcarbamate)-based chiral stationary phase (CDMPC-CSP). The degradation followed pseudo-first-order kinetics. The degradation of the (+)-TCYM was much faster than that of the (-)-TCYM in plasma, heart, liver, kidney, and fat after administration of racemic TCYM (rac-TCYM). The EFs were over 0.500 in these tissues and muscle. The results showed the conversion of (+)-enantiomer to (-)-enantiomer in plasma after injection of (-)- and (+)-TCYM separately. The results for the major differences in the degradation of the enantiomers may have some implication for the environmental and ecological risks assessment for chiral pesticides.