Residue analysis and degradation studies of two chiral pyrethroids in cabbage by ultra performance convergence chromatography

Abstract

A novel and accurate method was developed for the determination of the chiral isomers residue of bifenthrin and fluvalinate in cabbage by solid-phase extraction (SPE) in combination with ultra performance convergence chromatography (UPC²).

Four kinds of bifenthrin and fluvalinate isomers were well separated on a CHIRALPAK OJ-H chiral column within 5 min. The method obtained excellent calibration linearity (r² > 0.9992) and a satisfactory analysis of the targeted compound, which were evaluated with calibration standards over the range of 0.5–20 mg/mL. The recovery rates ranged from 80.4 % to 102 %, with relative standard deviations below 6.8 %. The limits of quantitation were 0.1–0.2 mg/kg in cabbage leaves. The residual amounts of bifenthrin and cyfluthrin isomers on cabbage were less than 0.5 mg/kg after 3 days of application. The residual half-life of the four pyrethroid isomers was about 2.5 days. There was no obvious enantioselectivity upon degradation between the isomers of bifenthrin and fluvalinate during the growth of cabbage leaves. None of the isomer residues of bifenthrin and fluvalinate were detected in 20 pieces of commercial cabbage samples. The method has the advantages of easy operation, satisfied separation effect and environmental friendly, and can meet the demand of the four kinds of isomers residue analysis of bifenthrin and fluvalinate. The results provided technical support for further research on the residue and degradation of chiral pesticides during vegetable growth.