| In this paper,nine common neonicotinoid insecticides,imidacloprid,acetamiprid,thiamethoxam,clothianidin,thiacloprid,dinotefuran,flonicamid and imidaclothiz were analysed as research objects.By using solid phase extraction technology combined with UPLC-MS/MS,we determinated the residues of neonicotinoid insecticides in rice soil,commercial fruits and vegetables,and human urine,then developed a method for determinating urinary neonicotinoid insecticides and assessed the exposure risk of neonicotinoids insecticides on this basis.The main work and achievements of the research were shown as followed:(1)Simultaneous determination of 9 neonicotinoid insecticides residues in fruits and vegetables and their cumulative risk assessment:all 9 neonicotinoids had high frequency of detection in vegetables and fruits.24 kinds of vegetable samples were detected for at least one neonicotinoid,green vegetables(acetamiprid for 140.5 ?g/kg)and Asparagus bean(thiamethoxam for 46.5 ?g/kg)contained the highest level of neonicotinoids.As for 12 kinds of fruits,all samples in this study were detected for at least one neonicotinoid,while flonicamid was the only neonicotinoid that is not detectable in fruits.Apple(imidacloprid for 45.3 ?g/kg)and pineapple(imidacloprid for 50.3 ?g/kg)have the highest levels of neonicotinoids.The results showed that the estimated median usual intake(UI)for the fruits and vegetables consumption is lower than the RfD for imidacloprid,and none of the 95th percentile of UI is exceeding the RfD.According to the gender difference,The UI were almost no difference between boys and girls.The accumulative consumption risk is under control.(2)A developed method for determining 9 neonicotinoid insecticides in human urine:this study developed extraction,purification and detection method of 9 neonicotinoids insecticides in human urine,and verified the method in sensitivity,precision,stability,and matrix effect at 2 mL of urine sample size.The results showed that the samples were purified by Oasis HLB as the solid phase extraction column. The target compound was eluted directly with dichloromethane:acetonitrile(7:3)and determined by UPLC-MS/MS.The available recovery ranges of 9 neonicotinoids were 80.8-103%(1 ?g/L),81.5-91.7%(25 ?g/L)and 83.0-92.3%(100 ?g/L),which were similar to 3 isotope-labled standards imidacloprid-d4(89.5-97.4%),thiamethoxam-d3(85.6-91.1%)and clothianidin-d3(84.7-101.0%).The detection rate of 9 neonicotinoid insecticides in children's urine samples was 10-80%.Four neonicotinoids with high detection rate were acetamiprid(80%),thiamethoxam(70%),imidacloprid(80%)and clothianidin(70%),respectively.Flonicamid and nitenpyram were not detected.Imidacloprid(ND-0.92 ?g/L),thiamethoxam(ND-1.42 ?g/L),acetamiprid(ND-0.92 ?g/L)and clothianidin(ND-1.94 ?gg/L)represented the relative higher residues levels.The recoveries of all samples were 82.03-91.50%and the relative standard deviations(RSD)were 0.1-2.7%.(3)Simultaneous determination of 9 neonicotinoid insecticides residues in rice soil:the residues of neonicotinoid insecticides in Zhejiang,Jiangsu,Guangdong and Jiangxi provinces' soil samples were widespread.In addition,the detection rates of imidacloprid,thiamethoxam,clothianidin and dinotefuran were higher in four provinces,and the detection rates of imidacloprid in four provinces were 96%in Zhejiang Province,100%in Jiangsu Province,96%in Guangdong Province and 96%in Jiangxi Province,respectively.The residual concentration range of neonicotinoid pesticide in soil samples is still within the acceptable range,the highest residue is 29.88 ?g/kg,and the recovery rate of all soil samples were 78.9-103.0%.According to the total average exposure concentration,Zhejiang Province was the highest,followed by Guangdong Province,Jiangxi Province and Jiangsu Province.In brief,the overall average exposure risk for the four provinces was lower than the chronic reference dose(cRfD)of imidacloprid.The accumulative consumption risk is acceptable. |
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