Characteristics Of Residue Fate And Risk Assessment Of Acetanilide Insecticides In 3 Minor Crops

Due to the problems of small planting area,low rate of return on pesticide registration,the enterprise for pesticide registration enthusiasm is not high,leads to the frequent wrong use and indiscriminate use of pesticides,which leading to serious pesticide residues in a lot of minor crops.In this study,a multi-residue analytical method of flubendiamide,flonicamid and chlorantraniliprole in chrysanthemum,honeysuckle and tobacco was established,the dissipation and terminal residue of the three pesticides were conduct and dietary intake risk assessment were evaluated.At the meantime,the change and transfer of pesticide residues during processing was also studied.In addition,the effect of foliar fertilizer on promoting pesticide residual degradation in tobacco Leaves was exlpored.The main results are as follows:1.A multi-residue analytical method of three pesticides in three minor crops was established and the dissipation and terminal residue of the three pesticides were conduct.Samples were extracted with acetonitrile,cleaned up by dispersive solid phase extraction with primary secondary amine,and detected by HPLC-MS /MS with quantification by external standard method.The result showed that in the range of 0.001-1 mg/L,the linearity of the peak area of chromatography and corresponding mass concentration of three pesticides in different minor crops were good.At the addition level of 0.005-10 mg/kg,the average recoveries were 82.6%-111.4%,with relative standard deviations less than 16.1%.Using the minimum addition level as LOQ,the limits of quantification(LOQs)were 0.004-1 mg/kg in different matrices.The dissipation and terminal residue of flubendiamide,flonicamid and chlorantraniliprole in chrysanthemum,honeysuckle and tobacco were conduct by the established method.Results showed that the degradation of three pesticides in three minor crops fitted for the first order kinetic equation and the half-lives of flubendiamide,flonicamid and chlorantraniliprole in three minor crops were 4.8-18.2 d,2.9-9.1 d and 3.4-13.6 d,respectively.The final residue results showed,when the harvest interval was 14 days,the maximum residues of flubendiamide,flonicamid and chlorantraniliprole was up to 0.6-22.0 mg/kg,1.4-16.3 mg/kg and 0.7-16.4 mg/kg,respectively.2.The effect of processing on residual transfer of three pesticides in three minor crops.We found that the four different drying methods can effectively reduce the residual of three pesticides in chrysanthemum and honeysuckle.During the soaking process,the dissolution ratios of the three pesticides increased with the increase of the soaking water temperature or the decrease of the ratio of tea to water,but decreased significantly with the increase of the soaking times.There was no significant effect of the soaking time or the soaking process was covered or not on the dissolution rate.During the burning and smoking of cigarettes,the transfer rate of 3 pesticides to mainstream smoke was in the range of 1.2% to 18.7%.Our results showed that the processing factors of immersing and burning were all less than 1,the dry processing factor was greater than 1.Through the dietary risk assessment,we concluded that the application of the three pesticides on chrysanthemum,honeysuckle and tobacco would not pose an unacceptable risk to the general population eating dried chrysanthemums,honeysuckle and chrysanthemums,honeysuckle tea,and cigarette smoking.3.The safety evaluations were conducted for application of three acetanilide insecticides on chrysanthemum,honeysuckle and tobacco.Based on the final residue results of field trials conducted in Shandong,Sichuan and Anhui provinces,the risk of dietary intake of three pesticides on three crops was evaluated in combination with the dietary structure of Chinese residents.The results showed that the RQcs of three pesticides in three minor crops were 4.6%-28.4%,the RQas were well below 100%.Thus it can be concluded that the application of three insecticides to three minor crops is safe for human health.4.Effect of foliar fertilizer on pesticide residual degradation in tobacco leaves was studied.Application of different concentrations of foliar fertilizer with 3 insecticides on Tobacco leaves,The result showed that foliar fertilizer had effects on reducing the target residues in tobacco.But,the effects varied from one pesticide to another.The results provided the basic data for reducing the level of tobacco pesticide residues and improving the quality of tobacco leaves through the "combination of pesticide and fertilizer " model.