Residues and decline dynamics of thifluzamide in rice field

An analysis method using gaschromatography-ion trap mass spectrometry (GC-ITMS) was developed for the determination of thifluzamide residues in water, soil, rice, plants and hulls. The residues and decline dynamics of thifluzamide in paddy field were conducted by field experiments. The calibration curve showed a good linearity in the range of 0.03-6 mg/L with the correlation coefficient above 0.99. The average recoveries of thifluzamide in five samples at three spiked levels of 0.03, 0.3 and 3 mg/kg all ranged from 71% to 100%, with the relative standard deviation (RSD) of 1.8% to11.4%. The limits of quantitation (LOQ) in those samples were 0.03 mg/kg. The limit of detection (LOD) was 0.01 mg/kg. The dynamic data were fitted by the first-order kinetics equation and second-order kinetics equation. Results show that the half-lives of thifluzamide were 2.4 to 9.2 d in paddy water, 1.8 to 10.3 d in the soil, and 1.3 to 4.1 d in the plant. And this study demonstrated that if the application rate of thifluzamide was below 169.2 g (a.i)/hm² with no more than three times application, the thifluzamide residues in rice at harvest time were below Chinese maximum residue limit (3 mg/kg).