Simultaneous determination of three pesticides and their metabolites in unprocessed foods using ultraperformance liquid chromatography-tandem mass spectrometry.

We have developed a rapid, multi-compound analytical method for measuring residues of the pesticides thiamethoxam and its metabolite, clothianidin; fipronil and its three metabolites, fipronil sulfone, fipronil sulfide, and fipronil desulfinyl; and pyraclostrobin in unprocessed foods (rice, corn, cucumbers, tomatoes, apples, and bananas) by ultra-performance liquid chromatography coupled to tandem mass spectrometry. Acetonitrile was used as the extraction solvent, and an octadecylsilane-dispersive SPE was used to clean up the analytes, which were then separated through a UPLC HSS T3 column connected to a tandem mass spectrometer via an electrospray ionisation source. The linearity of this method for the target analytes was excellent (R2 ≥0.990) in the concentration range of 5-1000 μg kg-1. The average recoveries of the seven compounds at concentrations of 10, 100, and 1000 μg kg-1 from six spiked matrix samples ranged from 73.6 to 110.6%, all with RSD values of ≤19.7%. The limit of quantification was 10 μg kg-1. The method validated the effectiveness of the method for routine monitoring the residue of these pesticides and their metabolites in foods.