Analysis of Multiple Pesticides Residue in Milk by Magnetic Extraction and Purification Technology Combined with Liquid Chromatography-Tandem Mass Spectrometry

(State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Agro-product Safety and Nutrition, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China)source under multiple reaction monitoring mode. The results showed that all the pesticides could be separated by chromatography within 10 min, and the linear relationship of 56 kinds of pesticides in their respective concentration range was good (r2=0.9752-0.9999), with limits of detection of 0.01-0.16 & mu;g/L. Furthermore, the method limits of quantification were 0.3-5 & mu;g/kg with recoveries of 69%-119% and RSD of 3%-20%. The method was applied to analysis of pesticide residues in 31 commercially available milk samples, and it was found that different concentrations of pesticides were detected in 12 brands of milk. Significantly, the residue concentrations were lower than the maximum residue limit levels stipulated in GB 2763-2021 and European Union standards. In particular, the accurate quantitative concentration and detection rate of chlormequat were 0.77-4.29 & mu;g/kg and 22.58%, respectively. According to the risk assessment of chronic and acute exposure, single exposure did not constitute significant dietary health risk. The method developed here was simple, rapid, and low consumption of sample and organic solvent, and could be used for the quantitative determination of 56 kinds of pesticides residue in milk with high sensitivity and accuracy.