Determination of Chlorantraniliprole, Flubendiamide and 2-Methyl-4-chlorophenoxyacetic Acid Residues in Milk by Ultra Performance Liquid Chromatography-tandem Mass Spectrometry

Objective: A method was developed for the determination of chlorantraniliprole, flubendiamide and 2-methyl-4-chlorophenoxyacetic acid in milk by ultra performance liquid chromatography-tandemmass spectrometry (UPLC-MS/MS). Methods: The samples were extracted by acetonitrile, salted out by sodium chloride, degreased by n-hexane and purified by two-step cryogenic centrifugation. The analytes were separated by Waters Acquity UPLC BEH C₁₈ chromatographic column. The mobile phase was eluted with a gradient of acetonitrile and 0.1% formic acid aqueous solution. The detection was carried out with electrospray ion source, positive and negative ion switching, scanning mode and the quantification was accomplished by external standard method of matrix standard curve. Results: The three pesticides showed a good linear relationship (R²>0.999) in the range of 10~150 ng/mL. With the addition of 5.0, 10.0 and 50.0 μg/kg in the standard recovery experiment, the recoveries were 73.3%~117.3% and the relative standard deviations were 1.0%~5.9% (n=6). The detection limits (S/N≥3) and the limit of quantification of the method (S/N≥10) were 1.0 and 5.0 μg/kg, respectively. Conclusion: This method is simple, accurate and sensitive, which is suitable for simultaneous determination of chlorfenoxamide, fluorofenoxamide and 2-methyl-4-chlorophenoxyacetic acid residues in milk.