Degradation dynamics of quinclorac in paddy field

Degradation dynamics of quinclorac in two treatments of paddy field (maintaining the field water through necessary irrigation, named treatment A, keeping the field water in natural sedimentation, named treatment B) was studied in Guangzhou in 2012. Liquid chromatography-tandem mass spectrometry analytical method was developed to determine the residue of quinclorac in water and soil. Results showed that the limit of detection (LOD) of quinclorac in water and soil was 0.001 mg/L and 0.001 mg/kg, respectively. The average recovery rate of quinclorac was from 83.93% to 106.75% in paddy water when the spiked level was 0.01, 0.1 and 1.00 mg/L or mg/kg, with the relative standard deviation (RSD) from 2.3% to 6.3%, and from 83.23% to 113.50% in paddy soil, with the RSD from 2.6% to 4.4%, respectively. The degradation of quinclorac in paddy water and paddy soil fitted for the first-order chemical kinetic equation C=Coe-kt. The half lives of quinclorac were 8.7 and 14.1 days in paddy water and paddy soil respectively in treatment A, and 10.8 days in paddy soil in treatment B.