The Establishment Of Methods For The Residual Determination Of Chlorfenapyr And Its Metabolites In Multiple Matrix And Dietary Risk Assessment

The rapid development of social economy has brought changes to the life of humans,and the living standard and quality of humans have been greatly improved.Chinese residents have a higher demand for green,safe and high-quality agricultural products.Therefore,the Chinese government also attaches great importance to food safety issues.Chlorfenapyr is widely concerned due to its low toxicity,high efficiency and remarkable activity.As one of the new pyrrole insecticides and acaricides,it can effectively replace the traditional highly toxic pesticide products,and has a wide application prospect.In 2018,Joint FAO/WHO Meeting on Pesticide Residues(JMPR)evaluated the definition of chlorfenapyr residue assessment,and the metabolite tralopyril was included in the dietary risk assessment of chlorfenapyr.The toxicity of tralopyril was 10 times than that of chlorfenapyr.The inclusion of metabolites in the dietary assessment would increase the dietary risk of chlorfenapyr.At present,the standard methods for the residual determination of chlorfenapyr in China do not include the detection of tralopyril,and tralopyril is not monitored in China.With the wide use of chlorfenapyr products,the detection methods of chlorfenapyr and tralopyril residues in multi-matrix were established.The dietary risk assessment of chlorfenapyr was carried out based on the current situation of chlorfenapyr registration in China,and clarified the dietary intake risk of chlorfenapyr and the contribution of tralopyril,which was significant to ensure food safety and guide the registration and use of chlorfenapyr in China.In this research,a method for the residual determination of chlorfenapyr and tralopyril in a variety of matrix was established.The established method was applied to residual experiments of crops and the residual monitoring of market samples.The dietary risk assessment of chlorfenapyr was conducted simultaneously considering tralopyril.The main results are as follows:1.A method for the residual determination of chlorfenapyr and tralopyril in vegetables,fruits,grains,oilseeds and tea based on the optimized Qu ECh ERS method was established.The linear range was 0.001～0.5 mg/L,R~2>0.995.The average recoveries were 82～101%with the relative standard deviation(RSD)of 0.8～13.1%,and the limit of quantitation(LOQ)was 0.01 mg/kg.The linear range,correlation coefficient,accuracy,precision and LOQ of the method met the requirements of pesticide residue trials in crops.The method has the advantages of high sensitivity,strong ability to remove impurities,simple pretreatment,good versatility and stability.2.Cabbage,the most registered crop of chlorfenapyr,was selected for residue test.The final residue test was carried out in Liaoning,Shanxi,Beijing,Shandong,Shanghai,Anhui,Hunan,Jiangxi,Guangxi,Chongqing,Guizhou and Guangdong,and the residue digestion test was carried out in Beijing,Shanghai,Hunan and Guangdong at the same time.Cabbage was treated by chlorfenapyr dosage of 120 g a.i./ha,which was spraying 2 times with 7 d-spraying interval,and cabbage samples were collected at 14 d and 21 d after the last application.The final residue of chlorfenapyr in cabbage was less than 0.01～0.471 mg/kg,which is under the limit of the maximum residue limit(MRL)of chlorfenapyr in cabbage in China(1 mg/kg);tralopyril was less than 0.01 mg/kg;the half-life of chlorfenapyr in four addresses was 2.15-5.37 d and the degradation was fast.3.Sixteen registered agricultural products of chlorfenapyr were selected and 320 samples were collected from 20 large supermarkets,small supermarkets and farmers markets in Tai’an City.The residues of chlorfenapyr and tralopyril were monitored by the established method.The results showed that the detection rate of residues in samples was 11.9%,the over standard rate of residues was 0.31%,and the qualified rate was over 99.5%.4.The dietary risk probability of including tralopyril in chlorfenapyr increased from68.5%to 69.5%,and the risk probability was less than 100%.In addition,the risk probability is slightly increased,indicating that tralopyril does not contribute to the dietary risk of chlorfenapyr.According to the assessment results,the current registration of chlorfenapyr in China will not cause unacceptable risk to the health of the general population.However,with the popularization of chlorfenapyr,the dietary risk will be further increased.At present,the dietary risk probability of 69.5%is at a high level,and the dietary risk of chlorfenapyr needs further tracking and continuous attention.