Abstract
Tau-fluvalinate (TFLV) is one of the most potent chiral synthetic pyrethroids to control a wide range of pests in agricultural fields, especially in apiary. In this study, two stereoisomers of TFLV were fully separated by high-performance liquid chromatography (HPLC) with a semipreparative chiral column using cellulose-tris(3,5-dimethylphenylcarbamate) as chiral stationary phase andn-hexane and 2-propanol (96/4, v/v) as mobile phase at a flow rate of 2.5 mL min−1. The (+)-stereoisomer was first eluted by detecting with an optical rotation detector. After obtaining pure single stereoisomer of TFLV, acute toxicities of each isomer and TFLV standard to zebrafish were evaluated. The results showed that the (+)-stereoisomer exhibited 273.4 times higher toxicity than the (−)-stereoisomer and 6.7 times higher than TFLV standard, according to their LC50values at 96 h after exposure. This indicates that the toxicity of TFLV mainly originates from (+)-stereoisomer. These results are very helpful to prepare single stereoisomer of chiral pesticides and evaluate their different toxicological effects to aquatic organisms.
Highlights
The study on chiral chemicals has become an important issue in recent years
TFLV standard which consisted of two stereoisomers with equal contents was supplied by Dr Ehrestorfer (Augsburg, Germany)
The effects of many factors including different composition of mobile phase and flow rate on the stereoselective separation were investigated using a standard solution with higher concentration (10000 mg L−1)
Summary
The study on chiral chemicals has become an important issue in recent years. About 25% of developed and marketed pesticides were chiral, in which at least two mirror images called enantiomers exist [1]. The first study about environmental enantioselectivity of pesticides began from the early 1990s [2]. Enantiomers can exhibit different biological properties and toxicity. The active part of enantiomers would affect target species, whereas others may not. Both of the enantiomers or one of them may give adverse effects on some nontarget species. More and more single- or enriched-enantiomer pesticides have been widely developed
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