Abstract: A modified QuEChERS coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of 18 succinate dehydrogenase inhibitor (SDHI) fungicides in fruits and vegetables. Samples were extracted with acetonitrile and salted out with anhydrous magnesium sulfate and sodium acetate, and then the supernatant was purified with primary secondary amine (PSA). The 18 compounds were separated on a C18 column by gradient elution using acetonitrile-0.1% (V/V) formic acid in water as the mobile phase, detected by MS/MS in both positive ion and negative ion mode using multiple reaction monitoring (MRM), and finally quantified by the external standard method. The calibration curves for all analytes showed good linearity with correlation coefficients (r) of above 0.99 in the concentration range of 0.5–200 μg/L. The limits of detection (LOD) and the limits of quantification (LOQ) of the developed method were 0.5–2.0 and 1.5–6.0 μg/kg, respectively. The recoveries of the analytes in four different matrixes each spiked at three levels (10, 50 and 150 μg/kg) ranged from 83.6% to 109.4% with relative standard deviations (RSD) of 1.2%–8.4% (n = 6). This method was easy to operate and showed good purification efficiency, and thus it could be applied to the rapid determination of SDHI fungicides in fruits and vegetables.

Key words: ultra-high performance liquid chromatography-tandem mass spectrometry; quick, easy, cheap, effective, rugged and safe; succinate dehydropgenase inhibitor fungicides; fruits and vegetables