Determination of 32 Kinds of Pesticide Residues in Raw Milk by Supported Liquid Extraction with LC-MS/MS

To provide scientific support for guaranteeing food safety in raw milk, a rapid method for the determination of pesticide residues in raw milk was developed using supported liquid extraction technique and ultra-performance liquid chromatography tandem mass spectrometry. The sample was precipitated with acetonitrile and then separated by high speed centrifugation. The supernatant was purified by SLE column. Separation of pesticide residues was achieved by a CORTECS C₁₈ column. Pesticide residues were detected by ultra-performance liquid chromatography tandem mass spectrometry with electrospray ionization in the multiple reaction monitoring mode, and the quantification was accomplished by external standard method of matrix standard curve. Method validation revealed satisfactory linearities with correlation coefficients higher than 0.9962, and limits of detection and quantification for target compounds were 0.1~2.5 μg/kg and 0.3~7.5 μg/kg, the average recoveries at three spiked levels were in the range of 69.4%~113.6% with relative standard deviation (RSD, n=6) less than 8.2%. This method is simple, quickly and reliable, and shows great promise for detecting 32 different pesticide residues in raw milk.