| ObjectiveImidacloprid is a new broad-spectrum pesticide.The mechanism of pesticide like Imidacloprid is different from others,and there is no interaction between them, which is the preferred pesticide for cotton,rice,vegetable and diversified fruit trees to prevent and cure pest with thorn mouth.The amount of imidacloprid use increases day after day because of its high efficiency,low toxicity,broad spectrum and long period of validity.Obviously it brings pollution on crop and environment. So we have to study the depurative method and determination of this pesticide in fruit and vegetable.This research intends to establish one kind of examination technology of Imidacloprid residue which is simple,fast and highly effective on one hand.We can analyze and inspect the pollution instance in time and exactly. On the other hand,by studying the activity of antioxidase,protein and glutathione under the different concentration of Imidacloprid stress in vegetable,we can make clear the dose-effect between concentration and the above active matter in salad, and the dose-effect between residual of Imidacloprid and the above matter in salad. We can establish a process to filtrate sensitive biomarkers in Imidacloprid polluted vegetable in early days.Method1.Field experiment is taken to spray high-dose,middle-dose,low-dose and without-dose Imidacloprid cream in salad field.The Imidacloprid cream was sprayed every other day and 3 times altogether.The salad samples were gathered in 0d,1d,3d,5d,7d,9d,11d after the last time Imidacloprid cream was sprayed. The Imidacloprid residue,the activities of antioxidant enzyme(peroxidase,catalase,superoxide dismutase),the polyphenoloxidase,the content of glutathione and protein were detected separately. 2.Salad samples were withdrawn by dichloromethane,purified by chromatographic column of alumina,silicon and magnesium sorbent,eluting by light petroleum,eluted by methanol,concentrated by rotary evaporator and detected by high performance liquid chromatograph(HPLC).3.The activities of peroxidase(POD),catalase(CAT),superoxide dismutase (SOD),polyphenoloxidase(PPO),the content of glutathione and protein were measured by guaiacol method,ultraviolet spectrophotometry,NBT assay,spectrophotography,Ellman method,and Coomassie brilliant blue G-250.Results1.The recovery rate of Imidacloprid in salad is 97%～100.4%,the accuracy is 3.5%～4.1%and the minimum detect ability is 0.16ng.The result showed a rapid degradation rate of the Imidacloprid residues in salad,and its degrading pattern is consistentwith one range reaction of dynamics.The half-value period of Imidacloprid residues in low-dose group is 2.67 days and its degeneration equation is y=687.89e-0.345x.The half-value period of Imidacloprid residues in middle-dose group is 2.43 days and its degeneration equation is y=1979.88e-0.379x.The half-value period of Imidacloprid residues in high-dose group is1.53days and its degeneration equation is y=7233.81e-0.466x.2.The activities of POD were affected evidently under Imidacloprid stress in salad.The activities of POD in processing groups were higher than control group and the activities of POD in high-dose group were higher than low-dose group. During the experiment,there was significance of difference of activities of POD between the control group and the treated groups(p＜0.05).3.The activities of CAT in treated groups were obviously higher than the control group.There was significance of difference of activities of CAT between the control group and the treated groups(p＜0.05).4.After the crop-dusting,the activities of SOD were highly improved in treated groups.The activity of SOD in low-dose group was maximized in five days. The activities of SOD in middle-dose group and high-dose group maximized in seven days,then reduced sharply after that.There was significance of difference of activities of SOD between the control group and the treated groups(p＜0.05).5.The activities of PPO in both high-dose group and low-dose group were higher than that in control group,and the activities of PPO in low-dose group is higher than high-dose group.The activities of PPO in low-dose group increased quickly after the crop-dusting,and maximized in seven days.It was equal to 3.3 times of the control group,and gradually reduced.There was significance of difference between low-dose group and the control group in eleven days.The activities of PPO in high-dose group maximized in five days,equal to 1.9 times of the control group and restored to basically approach with the control group in eleven days.6.After Imidacloprid insufflating,the content of protein in both high-dose group and low-dose group was lower than that in control group,and the content of protein in high-dose group is lower than that in low-dose group.The content of protein in low-dose group minimized in five days,then gradually increased,and restored to basically approach with the control group in eleven days.The content of protein high-dose group minimized in seven days,and there was significance of difference with control group in eleven days.7.The content of GSH in the two treated groups had the same change tendency,both rapidly reduced in an early time and later gradually increased.The content of GSH in low-dose group minimized in five days and in high-dose group minimized in seven days.Then it increased gradually.The content of GSH in low-dose group restored to basically approach with the control group in eleven days.Conclusion1.The sample pretreatment and detection which this experiment used are suitable for fast examination under the nicotinamide pesticide residue in vegetable.2.The Imidacloprid residues in salads degraded rapidly.3.POD,SOD,CAT,PPO,GSH and Protein all can be served as the biomarker under the Imidacloprid pollution.
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