ORIGINAL ABSTRACT

Currently, aryloxyphenoxy propionate (AOPP) herbicides, famous second only to glyphosate, have been widely used worldwide, such as cyhalofop-butyl, metamifop in rice ecosystem. In this work, field trials and QuEChERS liquid chromatography tandem mass spectrometry (LC-MS/MS) gave comprehensive residues in rice ecosystem for cyhalofop-butyl, metamifop, and their metabolites. Field trials involved 12 rice varieties and 12 sites with different climates and conditions. The determination method was reliable with average recoveries of seven analytes in brown rice, husk, and straw between 90.2% and 110.0%, with RSDs ≤ 16.0%. LOQs for seven analytes were lower than 0.01 mg/kg. Their degradation rates were < 21.7% at all storage intervals (168 days). Residues levels of seven analytes were consistently below their respective MRLs (< 0.01 mg/kg, China). Residue levels of cyhalofop-butyl (including cyhalofop and cyhalofop diacid) and metamifop (HPFMPA, HFMPA, and 6-CBO) were consistently below 0.03 and 0.04 mg/kg, respectively. Related chronic and acute risk quotients for cyhalofop-butyl, metamifop were < 1, indicating acceptable dietary risks. And children are exposed in environments with relatively higher risks. Due to the lack of reported residues, field trials, and dietary risk assessment, our work is useful for AOPP herbicides monitoring and related MRL issuing and provide data for herbicide management, food safety, and human health.