Dissipation kinetics and risk assessments of tricyclazole during Oryza sativa L. growing, processing and storage.

Because of the increase of people's attention to food safety, monitoring the residue of pesticide in rice is becoming more and more important. Commercial and home processing techniques have been used to transform paddy rice into rice products for human or animal consumption, which may reduce the pesticide content in rice. The degradation of tricyclazole during different stages of commercial and home processing and storage was assessed in this paper. Many researches studying the occurrence and distribution of pesticide residues during rice cropping and processing have been reported. Rice samples were extracted with acetonitrile, the extracts were enriched, and then residues were analyzed by liquid chromatography/tandem mass spectrometry method. The dissipation dynamics of tricyclazole in rice plant, soil, and paddy water fitted the first-order kinetic equations. The dissipation half-lives of tricyclazole in the rice plant, water, and soil at dosage of 300~450 g a.i. hm -2 were 4.84~5.16, 4.64~4.85, and 3.57~3.82 days, respectively. The residue levels of tricyclazole gradually reduced with different processing procedures. What is more, decladding process could effectively remove the residues of tricyclazole in raw rice, and washing process could further remove the residues of tricyclazole in polished rice. Degradation dynamic equations of tricyclazole in the raw rice and polished rice were based on the first-order reaction dynamic equations, and the half-lives of the degradation of tricyclazole was 43.32~58.24 days and 46.83~56.35 days in raw rice and polished rice. These results provide information regarding the fate of tricyclazole in the rice food chain, while it provides a theoretical basis for systematic evaluation of the potential residual risk of tricyclazole.