Residue Degradation And Dietary Risk Assessment Of Two Pesticides On Ric

Rice,as one of the main food crops in China,has a large planting area and is easily affected by various diseases and pests and grasses during its growth process.These factors will affect the yield of rice and even result in no production.Chlorantraniliprole and clothianidin,which are commonly used in rice,were used as materials in this study.The determination methods,namely,residual dynamics,were conductedby ultrahigh-performance liquid chromatography(UHPLC)tandem mass spectrometry.Dietary risks of chlorantraniliprole and clothianidin in rice were also explored.The main research results are as follows:The Qu ECh ERS method combined with UHPLC tandem mass spectrometry for the simultaneous determination of chlorantraniliprole and clothianidin residues in brown rice,rice husk,and straw was established.The linear relationship between chlorantraniliprole and clothianidin was good in the range of 0.1–100 μg/L,and the correlation coefficients were greater than 0.99.The average recoveries of the two insecticides in brown rice,rice husk,and straw ranged from 83.2% to 105.4%,and the correspondingrelative standard deviations were from 1.2% to 10.1%.The limits of quantitation of the two insecticides were 0.005 mg/kg in brown rice and 0.025 mg/kg in rice husk and straw.The residual dynamics of chlorantraniliprole and clothianidin in rice were studied.The dissipation behavior of chlorantraniliprole and clothianidin in rice in six fields a year all followed first-order kinetics,and the regression coefficient was greater than0.8472.The initial concentrations of chlorantraniliprole and clothianidin in rice of six locations ranged from 0.025 mg/kg to 3.641 mg/kg and from 0.042 mg/kg to 0.108mg/kg,respectively.The dissipation half-life of chlorantraniliprole in rice ranged from3.8 days to 30.1 days.The test site with the shortest half-life is in Guangxi Province,and the longest is in Heilongjiang Province.The dissipation half-life of clothianidin in rice ranged from 6.4 days to 16.5 days.The test site with the shortest half-life is in Jiangxi Province,and the longest is in Heilongjiang Province.The terminal residues of chlorantraniliprole and clothianidin in rice were analyzed.The residues of chlorantraniliprole and clothianidin in rice,brown rice,rice husk,and straw decreased gradually with the increase inharvesting time.The residues of chlorantraniliprole in rice ranged from < 0.010 mg/kg to 0.244 mg/kg,and the residues of clothianidin ranged from < 0.010 mg/kg to 0.496 mg/kg.All these values were less than the recommended maximum residue limit of 0.5 mg/kg.The residues of chlorantraniliprole in brown rice were < 0.005 mg/kg,and the residues of clothianidin were < 0.005–0.186 mg/kg.These values were smaller than the maximum residue limits of chlorantraniliprole and clothianidin in brown rice,which were0.5and 0.2mg/kg,respectively.The residues of chlorantraniliprole in rice husk ranged from <0.025 mg/kg to 0.963 mg/kg,and the residues of clothianidin ranged from < 0.025mg/kg to 1.735 mg/kg.The residues of chlorantraniliprole in straw ranged from <0.025 mg/kg to 3.179 mg/kg,and the residues of clothianidin ranged from < 0.025mg/kg to 4.155 mg/kg.The dietary risk assessment of chlorantraniliprole and clothianidin was conducted on the basis of the final residue test results of this study in combination with the dietary structure data released by our country,the recommended standardized residue test median value of residue chemical assessment,the established maximum residue limit,and the recommended daily allowable intake for brown rice.The national estimated daily intake of chlorantraniliprole in the general population was2.3025 mg,which accounted for 1.83% of the daily admissible intake.The national estimated daily intake of clothianidin in the general population was 0.4083 mg,which accounted for 6.48% of the daily admissible intake.This study provides scientific data support and theoretical basis for the application of chlorantraniliprole and clothianidin on rice and consumption of consumers.