Study On Residues Of Trifloxystrobin And Its Metabolite In Rice And Paddy Field

This study is to develope a new analycal methods for determination of trifloxystrobin and itsmetabolite CGA321113in soil, paddy water and rice, and to provide a safer mean. The dissipationdynamic and residue of trifloxystrobin and its metabolite CGA321113in soil, paddy water andrice were also investigated using the established method. A modified QuEChERS method and highperformance liquid chromatograph tandem mass spectrometry (HPLC-MS/MS) were employedfor this study.The method was based on QuEChERS methodology. The samples were extracted usingmixed solution of acetonitrile and acid water (0.1‰formic acid), and purified with C18, finallyanalyzed by HPLC-MS/MS. The results showed a good linearity, and the linear correlationcoefficients of trifloxystrobin and CGA321113were above0.999. The limits of quantification(LOQ) for trifloxystrobin in soil, rice plant and brown rice were0.01mg/L, and0.005,0.02,0.05mg/kg were in paddy water, rice husk and rice straw, respectively. The limits of quantification forCGA321113in soil was0.01mg/kg,0.005mg/kg was in paddy water,0.05mg/kg were in riceplant and rice straw,0.02mg/kg were in brown rice and rice husk. The average recoveries oftrifloxystrobin and CGA321113in paddy soil, water and rice samples were76.5%~103%and75.1%-105.4%, respectively, with the relative standard deviations (RSD)1.1%-8.9%and0.9%-15%, respectively.The field trials of trifloxystrobin were conducted in Beijing, Hubei and Zhejiang province in2012and2013. The results of degradation dynamics trials demonstrated that the dissipation oftrifloxystrobin in soil, paddy water and rice plant were fitted to the first-order kinetics equationCt=C0e-kt, and the half-lives of trifloxystrobin were1.18-6.22d、0.85-1.47d and5.04-7.33,respectively. By spraying3times and4times according to the higest recommended dosage and1.5times higest recommended dosage,14days after spraying, the residues in brown rice werebelow the MRL set by CAC5mg/kg, the residues in rice husk and rice straw were below theMRLs set by USA8mg/kg and5mg/kg, respectively.There are differences in the residues of trifloxystrobin and CGA321113in soil and paddy. Themain residues in soil were CGA321113. Because of quickly degradation, the residues of trifloxystrobin and CGA321113in paddy water were almost same. The main residues in rice plant,rice, rice husk, rice straw were trifloxystrobin, while the amount of CGA321113was relativelylower than trifloxystrobin.