| Cowpea production process is very vulnerable to pests and diseases,because cowpea bears beans while blooming,so vegetable farmers often use pesticides during the harvest period to control pests and diseases during the flowering period.So the problem of pesticide residues is prominent.In view of the actual situation of cowpea production and medication in a certain region,this thesis took nine common neonicotinoid insecticides(imidacloprid,acetamiprid,thiamethoxam,clothianidin,thiacloprid,dinotefuran,nitenpyram,sulfoxaflor and imidaclothiz,etc.)as the research object,and established a detection method for neonicotinoid insecticides by Qu ECh ERS or solid-phase extraction combined with UPLC-MS/MS technology,and the detection methods of neonicotinoid insecticides in local cowpea,residual levels of soil and human exposure samples(urine)are monitored to provide technical support for the safe production of cowpea.The main contents are as follows:(1)Residue monitoring of neonicotinoid pesticides in cowpeas: pesticides were detected in each of the 16 markets,and the detection rate of neonicotinoid insecticides in 3vegetable markets in a certain place was high,and more than 3 neonicotinoid pesticides were detected in 6 of the 71 samples.The detection rates of acetamiprid,imidaclothiz and nitenpyram were 29.41%,39.71% and 11.76%,respectively.The residual ranges of acetamiprid and nitenpyram were <0.01～0.38 mg/kg and <0.01～0.17 mg/kg,respectively,while sulfoxaflor,thiacloprid and clothianidin were not detected in cowpeas.The pesticide residues meet the requirements of the maximum residue limit standard in cowpeas(or beans)stipulated in the National Food Safety Standard Maximum Residue Limits of Pesticides in Food(GB 2763-2021).(2)Residue monitoring of neonicotinoid insecticides in soil: imidacloprid,thiamethoxam,imidaclothiz,clothianidin and acetamiprid were detected in 80 soil samples,among which the residual concentration of pesticides in cowpea field soil was high(8.9～477.6 μg/kg),while the soil concentration of other adjacent crops was relatively low(4.7～119.5 μg/kg).The residue ranges of imidacloprid,thiamethoxam and nitenpyram in soil were <0.1～325.0 μg/kg,<0.1～243.4 μg/kg and <0.1～25.7 μg/kg,respectively.The detection rate and residue of sulfoxaflor and thiacloprid were low,11.3%,25.0% and <0.1～0.54 μg/kg,and <0.1～7.5 μg/kg,respectively.The concentration and types of neonicotinoid pesticides in agricultural soils measured in this study were basically the same as those reported previously,while the concentrations in non-agricultural soils were much lower than previously reported.(3)Exposure level of neonicotinoid pesticides in human urine: The exposure level of neonicotinoid pesticides in 294 urine samples of residents in a rural area was monitored,and the detection rate was 5.10～87.41%.Among them,imidacloprid(87.4%),thiamethoxam(83.3%),acetamiprid(70.4%),clothianidin(82.7%),and nitenpyram(85.0%)had higher detection rates,and thiamethoxam(<0.1～35.57 ng/m L),acetamiprid(<0.1～12.99 ng/m L)and clothianidin(<0.1～53.29 ng/m L)was detected at a high concentration.The total exposure of42 volunteers for 7 days was: clothianidin > thiamethoxam > acetamiprid> nitenpyram >sulfoxaflor > imidaclothiz > imidacloprid > thiacloprid.Exposure to pesticides was higher in men than in women,but there was no clear difference;Except for clothianidin exposure,which was significantly higher in the adult group than in the juvenile group and the elderly group,there was no significant difference in the remaining pesticide exposure in the three groups. |
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