Abstract: Afidopyropen, a novel biorational insecticide, was registered in China in 2023 for the control of tea leafhoppers in tea plantation. In this study, an analytical method was developed for the determination of afidopyropen and its metabolite M440I007 in tea tissues by a modified QuEChERS method combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Roots, stems and leaves of tea plants were extracted by water and acetonitrile, and purified with primary secondary amine (PSA), hydroxylated multi-walled carbon nanotubes (MWCNT-OH) and graphitized carbon black (GCB). The target compounds were determined by UPLC-MS/MS in multiple reaction monitoring (MRM) mode, and quantified by external standard method with matrix-matched standard curve. Both targets display excellent linearity (R²>0.999 5) in the range of 0.002-5.000 mg·L^-1. The recoveries of both compounds at the spiked levels of 0.005-2.000 mg·kg^-1 ranged from 78.3% to 106.0% with the relative standard deviations (RSD) ≤ 12.85%. The limits of quantification (LOQs) and detection (LODs) of the method were 0.005 mg·kg^-1and 0.002 mg·kg^-1, respectively. The developed method was applied to detect afidopyrofen and M440I007 in tea seedling tissues cultured in soil treated with afidopyropen in a pot experiment for 7 days. The results show that the distribution of afidopyropen in the tissues was roots (0.102 mg·kg^-1) > stems (0.078 mg·kg^-1) > leaves (0.007 mg·kg^-1). The translocation factors, TF_root-stem and TF_stem-leaf, were both less than 1, and the residue levels of the metabolite M440I007 were below the LOQ. The method established in this study is low-cost, accurate and sensitive, which can serve as a technical basis for further research on the uptake and transport behaviors of afidopyropen and M440I007 in tea plants.

Key words: tea plant, pesticide residues, afidopyropen, M440I007, detection method