Abstract: Using the QuEChERS and ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)technology, a detection method of abamectin B1a residues in various rice matrices was established. The results showed that the method exhibited good linearity in the concentration range of 0.005-0.500 mg/L (r≥0.995). The limits of quantification (LOQ) in brown rice, rice husk and straw were 0.01, 0.01 and 0.02 mg/kg, respectively. The recoveries ranged from 71% to 92%, with relative standard deviations of 3%-11%, meeting the requirements for residue analysis. Field trials indicated that abamectin degraded rapidly in rice. The half-lives in rice husk and paddy rice at the Hainan experimental site were 1.2 d and 1.7 d, respectively. At the final residue stage, abamectin residues in brown rice were all below the LOQ. Only a small amount of residues was detected in rice husk and straw at the Hainan site, and the residue level in rice husk was higher than that in brown rice, suggesting that abamectin mainly accumulated in rice husk. Rice dehulling could effectively reduce abamectin residues. The established method was efficient and reliable, and could provide technical support for the rational application of abamectin on rice and the supervision of agricultural product quality and safety.

Key words: QuEChERS, ultra-high performance liquid chromatography-tandem mass spectrometry, rice, abamectin B1a, residue