Dispersive solid-phase extraction combined with dispersive liquid-liquid microextraction for simultaneous determination of seven succinate dehydrogenase inhibitor fungicides in watermelon by ultra high performance liquid chromatography with tandem mass spectrometry.

Abstract

In this study, a simple and accurate sample preparation method based on dispersive solid-phase extraction and dispersive liquid-liquid microextraction has been developed for the determination of seven novel succinate dehydrogenase inhibitor fungicides (isopyrazam, fluopyram, pydiflumetofen, boscalid, penthiopyrad, fluxapyroxad, and thifluzamide) in watermelon. The watermelon samples were extracted with acetonitrile, cleaned up by dispersive solid-phase extraction procedure using primary secondary amine, extracted and concentrated by the dispersive liquid-liquid microextraction procedure with 1,1,2,2-tetrachloroethane, and then analyzed by ultra high performance liquid chromatography with tandem mass spectrometry. The main experimental factors affecting the performance of dispersive solid-phase extraction and dispersive liquid-liquid microextraction procedure on extraction efficiency were investigated. The proposed method had a good linearity in the range of 0.1-100µg/kg with correlation coefficients (r) of 0.9979-0.9999. The limit of quantification of seven fungicides was 0.1µg/kg in the method. The fortified recoveries of seven succinate dehydrogenase inhibitor fungicides at three levels ranged from 72.0 to 111.6% with relative standard deviations of 3.4-14.1% (n=5). The proposed method was successfully used for the rapid determination of seven succinate dehydrogenase inhibitor fungicides in watermelon.