Determination of 11 pesticide residues in three vegetables by UPLC-MS /MS

This paper described a method for the determination of 11 pesticides residues in cabbage,cowpea and spinach by ultrahigh-performance liquid chromatography-tandem mass spectrometry( UPLC-MS /MS). The samples were extracted with acetonitrile and cleaned-up with Cleanert-NH2. The separation was performed on ACQUITY UPLC  BEH C18 column. The methanol-water with different proportion was used as mobile phase and the ionization efficiency,resolution and sensitivity were compared. 11 pesticides were determined in the modes of electrospray ionization and multiple reaction monitoring. The analytes were quantified by matrixmatched internal standard method. The calibration curves show good linearity in 5 ~ 100 μg·L- 1for each pesticide(R 0. 99). The limits of detection(LODs)were in the range of 0. 05 ~ 0. 5 μg·kg- 1. The recoveries of all the pesticides varied from 80% to 120%with the relative standard deviations of 2. 7% ~ 16. 3% at the spiked levels 0. 01,0. 05,0. 10 mg·kg- 1for all pesticides.