Establishment Of A Multi-Residue Detection Method For Pesticides In Strawberries And Research On Dietary Risk Assessment

Strawberry is a popular fruit variety among consumers,which is prone to diseases and insect pests in the growth stage,so it is inevitable to use chemical pesticides to control it,resulting in pesticide residues.In this paper,a multi-residue analysis method for 106 pesticides and metabolites such as acetamiprid in strawberry was established,and the pesticide residues in 139 strawberry samples randomly sampled from the market were determined.The chronic and acute dietary risks of 14pesticides with high detection rate such as pyraclostrobin in strawberries to different populations were evaluated.The effects of different cleaning agent types,cleaning time and concentration on the removal rate of carbendazim and other eight pesticides in strawberry samples were discussed.The main results are as follows:（1）QuEChERS method combined with Ultra Performance Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry was used to determine the residues of 106 pesticides and their metabolites in strawberry.The results showed that 106 pesticides and their metabolites had a good linear relationship between 1-200 ng/m L,and the correlation coefficient（r²）was greater than 0.9932;The average recoveries of 106 pesticides and their metabolites ranged from 60.0%to124.0%and the precision ranged from 1.25%to 30.28%at the levels of 0.005,0.05and 0.5 mg/kg,which met the requirements of multi-residue analysis of pesticides.The quantitative limit of 106 pesticides and their metabolites was 0.005 mg/kg.（2）The results of 139 strawberry samples showed that pesticide residues were detected in 135 samples.A total of 28 pesticide varieties were detected,among which20 kinds of fungicides were detected the most;The detectable concentrations of 28pesticides ranged from 0.005 to 3.56 mg/kg,and the average detectable value ranged from 0.017 to 0.517 mg/kg.Up to 14 pesticides can be detected in the same strawberry sample;4-10 pesticides can be detected in 113 strawberry samples at the same time.（3）The risk assessment results of chronic dietary exposure of 14 typical pesticides such as pyraclostrobin to different populations showed that the risk probability was between 0.01 and 2.86%,all of which were less than 100%,which was an acceptable risk;Among them,the most risky ones are iprodione and dithiocarbamide,both of which are far less than 100%.The acute dietary exposure risk the risk probability of six pesticide residues such as pyraclostrobin to different populations is between 0.69%and 13.83%,all of which are less than 100%,which is an acceptable risk;Among them,the most risky ones are iprodione and dithiocarbamide,both of which are far less than 100%.The risk probability of procymidone on acute dietary exposure risk of different populations is between 214%and 652%,greater than 100%,which is an unacceptable risk.（4）The removal rates of 8 pesticides including carbendazim in market strawberries were compared with tap water,1%Na HCO₃,1%Na Cl,1%starch and0.2%fruit and vegetable cleaning agent.The results showed that the comprehensive cleaning effect of 1%Na Cl solution was the best.Using 1%Na Cl solution as cleaning agent,the results showed that cleaning time had no obvious effect on the removal rate of carbendazim and other 8 pesticides in strawberry,and the removal rate of carbendazim and other 8 pesticides in strawberry was significantly improved by increasing the concentration of Na Cl solution（0.5%-1.5%）.