Residue analysis, dissipation behavior, storage stability and dietary risk assessment of florpyrauxifen-benzyl in natural paddy field environment using UPLC-QTOF-MS/MS

Abstract

Florpyrauxifen-benzyl is a new kind of herbicide for controlling troublesome weeds in rice production, and its dissipation and residues in the paddy field environment were investigated using UPLC-QTOF-MS/MS coupled with a QuEChERS method to evaluate the safety of its use in rice plantations. The LOD and LOQ for florpyrauxifen-benzyl in five environmental samples of paddy field were 0.42–1.14 µg/kg and 0.94–2.07 µg/kg, respectively, and all calibration curves showed good linearity (R2 > 0.9996) in a certain concentration range. The average intra-day and inter-day recovery rates of florpyrauxifen-benzyl from five blank matrices spiked at 50, 250 and 500 µg/kg ranged from 94.8% to 112% with an RSDr of 1.13–6.28%, and 96.0–111% with an RSDR of 1.52–4.76%, respectively. These results demonstrated that the developed method has a high sensitivity, specificity, accuracy and precision. All paddy filed environmental samples frozen at − 20 ℃ were analyzed within 6 weeks after collection to ensure no degradation during storage. Meanwhile, the dissipation dynamics of florpyrauxifen-benzyl in paddy water, paddy soil and rice straw followed the first-order kinetics and its half-lives were less than 3 days. Residues of florpyrauxifen-benzyl and its main metabolite florpyrauxifen on/in brown rice would not pose dietary risk to Chinese consumers of different age groups at the maximum residue level. Moreover, 1.0 wt% NaCl solution had the highest removal efficiency for florpyrauxifen-benzyl residues on/in brown rice. These results will contribute to guiding the practical application of florpyrauxifen-benzyl and minimizing the environmental risks associated with its global use.