Residue analysis method and dissipation dynamics of pyriclobenzuron in paddy fields studied by HPLC-MS using the QuEChERS method

Pyriclobenzuron is a newly developed molluscicide designed to manage pomacea canaliculata, yet its environmental behavior remains unexplored. This study developed and validated a residue detection method using HPLC-MS in conjunction with an optimized QuEChERS pre-treatment, enabling the analysis of pyriclobenzuron dissipation dynamics and final residue levels in a rice field environment. The method demonstrates excellent linearity (R² ≥ 0.99) over the concentration range of 0.005–5 mg/L. Limits of detection (LOD) and quantification (LOQ) were determined to be 0.00052–0.00294 mg/kg and 0.00132–0.00945 mg/kg, respectively. Intraday and inter-day recovery rates ranged from 71.76 % to 95.19 %, with RSDr values between 0.83 % and 5.42 % and RSDR values from 1.04 % to 5.10 %, confirming the method’s precision and reliability. The dissipation kinetics of pyriclobenzuron in paddy water, rice plants, and paddy soil followed a first-order model, with half-lives (t_0.5) of 12.98–15.97 days in soil and 11.00–12.20 days in rice plants, indicating rapid degradation. Final residue analysis revealed that, at harvest, residues were primarily concentrated within the rice plants, while levels in brown rice remained below the quantification limit.