Dissipation dynamic of quintrione in rice plants and terminal residue in rice straw, grain and soil

Quintrione (2-(3,7-dichloroquinoline-8-carbonyl) cyclohexane-1,3-dione) is a new post-emergence herbicide just approved by Ministry of Agriculture and Rural Affairs in China. However, the potential environmental pollution caused by quintrione has not been investigated to date. A combined high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was developped for the analysis of quintrione residue in rice plant, grain and soil. The dissipation and terminal residues of quintrione in rice plant were determined by using this method. Results showed that there was a good linear correlation between the concentrations and peak areas with R² higher than 0.99. The average recoveries of quintrione in rice plant, soil, paddy water, paddy hull and brown rice varied from 78% to 99% with the relative standard deviation (RSD) ranged from 3.9% to 11%. The limits of quantification (LOQ) of quintrione in rice plant, soil, paddy water, paddy hull and brown rice were all 0.002 mg/kg. The investigation of dissipation dynamic data revealed that quintrione degraded quickly in rice plants with half-life (t_1/2) values betwwen 6.7 to 12.8 days. 96 days after quintrione application at 900 and 1 350 g a.i./ha on rice seedling, no terminal residual was detected in paddy soil, paddy hull, or brown rice samples. The study will contribute to the setting of the maximum residue limits (MRL) of quintrione in rice and the field application strategy.