Abstract: A method was developed for the determination of flusulfinam and flufenoximacil residues in five common types of fruits and vegetables (broccoli, yardlong bean, citrus, grape, and banana) using dispersive solid-phase extraction (dSPE) as the sample preparation technique coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Samples were extracted with 0.1% formic acid in acetonitrile (V/V) and cleaned up with primary secondary amine (PSA). The separation was achieved on a ZORBAX RRHD Eclipse Plus C18 column (2.1 mm × 50 mm, 1.8 µm) using a mobile phase consisting of ultrapure water and acetonitrile. Quantification was performed using a matrix-matched calibration curve with external standard calibration. The calibration curves for flusulfinam and flufenoximacil demonstrated good linearity over the concentration range of 0.5 to 100.0 ng/mL, with coefficients of determination ranging from 0.999 68 to 0.999 97. The limits of detection (LOD) and limits of quantification (LOQ) for both compounds were 0.5 and 1.0 μg/kg, respectively. At spiked levels of 1.0, 10.0, and 50.0 μg/kg, the average recoveries for flusulfinam and flufenoximacil ranged from 88.7% to 110.9% and from 93.9% to 119.7% with relative standard deviation (RSD) ranging from 2.3% to 7.3% and from 1.5% to 8.0%, respectively. The method is simple, fast, sensitive, accurate, and suitable for simultaneous determination of flusulfinam and flufenoximacil residues in fruits and vegetables, providing technical support for the detection and dietary risk assessment of these newly developed herbicides in domestic and imported agricultural products.

Key words: dispersive solid-phase extraction; ultra-high performance liquid chromatography-tandem mass spectrometry; flusulfinam; flufenoximacil; fruits and vegetables