Determination of avermectin residues in tea by ultra-performance liquid chromatography-electrospray tandem mass spectrometry

A simple and rapid analytical method for the simultaneous determination of abamectin, emamectin, eprinomectin, ivermectin, doramectin and moxidectin residues in tea by ultra-performance liquid chromatography-electrospray tandem mass spectrometry (UPLC/ESI-MS/MS) has been developed. The avermectins were extracted from the tea with acetonitrile after the tea was infiltrated in saturated aqueous NaCl solution, then cleaned up with a C18 solid phase extraction cartridge. The linear ranges were 2.0 - 50 mu g/L and the correlation coefficients were all above 0.9920. Several UPLC-MS/MS conditions that included the mobile phase, monitor ions and the selection of calibration of the measurement were studied. The average recoveries and the relative standard deviations ranged from 61.7% to 85.4% and from 9.37% to 17.19%, respectively, in spiked samples at the concentrations of 5, 10, 20 mu g/kg for moxidectin and 2, 5, 10 mu g/kg for other analytes. This method is suitable for the determination of avermeetin residues in tea.