Abstract:This study explored a test method for the determination of acibenzolar-S-methyl and acibenzolar acid in milk and dairy products by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The samples were subjected to vortex extraction with formic acid-acetonitrile (containing 1% (V/V) formic acid), and purified by QuEChERSdSPE EMR-Lipid tubes, centrifuged then filtered before detection. The test method used gradient elution using methanol-0.1% (V/V) formic acid as the mobile phase, a flow rate of 0.2 mL/min and ACQUITY UPLC HSS T3 column for separation. Electrospray positive and negative ion modes (ESI+ for acibenzolar-S-methyl and ESI- for acibenzolar) and multiple reaction monitoring (MRM) were used for detection, and the matrix-matched external standard method was used for quantification. For milk and dairy products, good linearity between the mass concentrations of acibenzolar-S-methyl and acibenzolar acid, and their corresponding peak areas, in the concentration range of 1~30 ng/mL, with the correlation coefficients R2 higher than 0.996. The mean recoveries of acibenzolar-S-methyl and acibenzolar acid were 91.8%~109.6% and the corresponding relative deviation (RSD) values were 1.3%~11.5% at three spiking levels (0.01, 0.02 and 0.1 mg/kg). This method can meet the requirements of accuracy, precision, and sensitivity for residue detection.
