Simultaneous determination of pesticide residues in crops by liquid chromatography with tandem mass spectrometry

A simultaneous method using liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was developed for the determination of pesticide residues in crops. Mass spectral acquisition was performed in the positive mode by applying multiple reaction monitoring. In LC separation, an Atlantis dC18 Column was used with acetic acid-ammonium acetate-acetonitrile as the mobile phase. Pesticide residues in crops were extracted with acetone, and cleaned up by liquid-liquid separation with saturated salt solution and hexane, followed by an ENVI-Carb cartridge. The quantification limits of compounds in crops were below 5 ng/g. Eighty compounds were obtained with recoveries ranging from 60 to 130% at the level of 50 ng/g with RSD (%) of less than 15%. Fifty crop samples were analyzed by the developed method. Seven pesticide residues were detected in nine crops.