Study On The Residue And Digestion Dynamics Of Chiral Pesticide Toxic Fluorine And Phosphorus On Rice

Rice is one of the important food in Asia.The disease caused by Southern rice black-streaked dwarf virus(SRBSDV)and rice stripe virus(RSV)are a significant virus disease in rice region of China.The disease constitutes a great threat to rice healthy growth.Dufulin is a new aminophosphonate antiviral agent in our country,and has been demonstrated to be highly effective in preventing viral infections and controlling caused by tobacco mosaic virus(TMV),cucumber mosaic virus(CMV),and SRBSDV,and it has been granted a national invention patent in China.Dufulin has a chiral center and is a chiral compound.In this paper,a simple and rapid method for enantioselective determination of dufulin in rice and soil was established by high-performance liquid chromatography.in this experiment,The rice samples were extracted with methylene chloride?acetonitrile?the mixture of methanol and water and et.al.,and then cleaned up,The extracts detected by HPLC.The results showed that good linearity with correlation coefficient of 0.9999 was found at the rang of 1~200?g/mL,The limits of detection(LOD)of two dufulin enantiomers were 7.1×10~-99 and 8.2×10~-99 g,respectively.The limits of quantification(LOQ)of two dufulin enantiomers in water were 0.025 mg/kg,in soil and brown rice were 0.050 mg/kg,in rice hull and rice culm were 0.20 mg/kg.The average recoveries of S-enantiomer and R-enantiomer in rice were 76.33~103.38%and 76.23~106.25%,with the relative standard deviation were 0.77~9.58%and 1.89~9.00%,respectively.The accuracy and precision of the method meet the requirements of pesticide residues analysis.The field trials of were conducted in Guizhou,Anhui,and Hunan province during the agricultural season in 2016 and 2017 to determine the dissipasion dynamics and terminal residues of dufulin(SC,20%)in rice.Using the established analysis method to detection of dufulin enantiomers in rice sample.The results show of the residual dynamics(the dosage was 450 g.a.i/ha and applied two times),the half-lives of the S and R enantiomers in rice clum from Anhui were 8.3 and 7.8 days,and in rice clum from Hunan were 6.7 and 6.6 days,respectively,in 2016.The final residues(the dosage was 300~450 g.a.i/ha and applied two and three times)of the S and R enantiomers on brown rice were<0.050~5.00 mg/kg and<0.050~4.67 mg/kg respectively.The results of this study provide data support for the safe use of chiral pesticides on rice.