Residueanalysisofivermectinon<italic>Myricarubra</italic>basedonQuEChERS-ultraperformanceliquidchromatography-tandemmassspectrometry

In order to evaluate the residual risks of ivermectin in Myrica rubra(Lour.)S.et Zucc. (waxberry), a residue analysis method of ivermectin in waxberry was developed. And the residue dynamics was studied based on field trials conducted in Zhejiang Province, Fujian Province, Jiangxi Province and Yunnan Province. The modified QuEChERS method coupled with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to detect the residues in samples. The results showed that a good linear relationship (r = 0.999 9) was obtained for ivermectin within the concentration range from 0.005 to 1 mg/L. Meanwhile, the average recoveries were 80%-95% with the maximum RSD of 9.9% at the spiked concentration range from 0.005 to 1 mg/kg. The recovery results inferred the accuracy and precision were accorded with the request of residue analysis. The LOD and LOQ of this method were 0.15 ng and 0.005 mg/kg, respectively. The field trial result showed that the initial residue of ivermectin in waxberry was 0.21-0.88 mg/kg and the half-life was 2.1-6.1 d, which revealed that ivermectin was an easily degradable pesticide. However, attention should be paid to the potential residue risks for the relatively higher initial residue.