Li Z Y, Zhang Z C, Zhang L, Leng L
College of Science, Hebei University of Science and Technology, Shijiazhuang, 050018, People's Republic of China.
Bull Environ Contam Toxicol. 2008 Apr;80(4):335-9. doi: 10.1007/s00128-008-9368-y. Epub 2008 Mar 3.
beta-Cypermethrin (beta-CP) and beta-Cyfluthrin (beta-CF) are two important pyrethroid insecticides and both consist of two enantiomeric pairs (diastereomers), i.e. four enantiomers. In this study, the stereo and enantioselective degradation of beta-CP and beta-CF in a Tianjin alkaline soil was studied in details by a combination of achiral and chiral HPLC. The results showed that for the two pyrethroids, the transdiastereomer was degraded faster than the corresponding cis-diastereomer. beta-CP and beta-CF were found to be configurationally unstable in this soil, since isomerization between diastereomers was observed during the degradation process. Further enantioselective analysis showed that significant enantioselectivity occurred during the 30 days incubation time. The enantiomeric ratio (ER) values of cis- and transdiastereomers changed from initial approximately 1.00 to final 0.79 and 0.55 for beta-CP, and to 0.64 and 0.48 for beta-CF, respectively. At last, it was found that beta-CF was degraded at relatively faster degradation rate and higher enantioselectivity than beta-CP. Findings from this study may be used to better understand the chiral profiles of beta-CP and beta-CF as well as relevant pyrethroid analogues in environment.
高效氯氰菊酯（β-CP）和高效氟氯氰菊酯（β-CF）是两种重要的拟除虫菊酯类杀虫剂，均由两对对映体（非对映异构体）组成，即四种对映体。本研究采用非手性和手性高效液相色谱联用的方法，详细研究了β-CP和β-CF在天津碱性土壤中的立体和对映体选择性降解。结果表明，对于这两种拟除虫菊酯，反式非对映异构体的降解速度比相应的顺式非对映异构体快。在该土壤中发现β-CP和β-CF构型不稳定，因为在降解过程中观察到非对映异构体之间的异构化。进一步的对映体选择性分析表明，在30天的培养期内发生了显著的对映体选择性。β-CP顺式和反式非对映异构体的对映体比率（ER）值从初始的约1.00分别变为最终的0.79和0.55，β-CF则分别变为0.64和0.48。最后发现，β-CF的降解速率相对较快，对映体选择性也高于β-CP。本研究结果可用于更好地了解β-CP和β-CF以及环境中相关拟除虫菊酯类似物的手性特征。
