Abstract: A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established for the determination of spinosyns A and D residues in foodstuffs. The food samples were extracted with acetonitrile-water (50:50, v/v), and then purified by an HLB solid phase extraction (SPE) column. The analytes were determined by HPLC-MS/MS and quantified by external standard method. The mass spectrometric detection was operated with electrospray in positive ionization mode and the spinosyns A and D were identified in multiple reaction monitoring (MRM) mode. The linear range of the method was 1-20 μg/L, with the correlation coefficient (r2) of 0.9999. No significant matrix effect was found for spiked samples. The recoveries of spinosyns A and D spiked in food were 76.2%-114.0% at the spiked levels of 1-10 μg/kg. The relative standard deviations (RSDs) were less than 10%. The limits of detection (LODs) and quantification (LOQs) were 0.2 μg/kg and 0.5 μg/kg for spinosyn A, 0.5 μg/kg and 1.0 μg/kg for spinosyn D, respectively. The proposed procedure was applied to the analysis of 969 real samples from Xiamen, Fujian Province (China), of which 15 positive samples were found. The results showed that the proposed method is sensitive and accurate for the determination of spinosyns A and D in foodstuffs.

Key words: food, spinosyn D, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), spinosad, spinosyn A