Study On Enzyme-Linked Immunosorbent Assay And Removing Techniques For Pyrethroids Residue

Pyrethroids are a group of pesticides widely used in agriculture and are found easily and commonly in agricultural products. It is necessary to develop a kind of economical, effective, and rapid screening method to monitor levels of pyrethroids residue to ensure the safety of human and environment. It is feasible to remove the residue of beta-cypermethrin Which is on the leaves of vegetables. The generic antibody which was raised against 3-phenoxybenzoic acid (PBA) conjugate with Bovine Serum Albamin(BSA) was applied to detect pyrethroids simultaneously. The enzyme-linked immunosorbent assay (ELISA) protocol was developed to screen the residue of pyrethroids on the vegetables. Moreover, removing techniques for pyrethroids residueon vegetables were preliminary probed. The results were reported as follows:1. PBA was used as generic hapten in order to generate broad specificity antibody against a group of pyrethroid insecticides. An indirect competitive ELISA(IC-ELISA) was developed. Assay performance was improved by the use of a coating antigen which possessed a four carbon spacer arm between the hapten and BSA. Typical detection limits for PBA was 0.2172ng-mL-1 with an I50 value of 3.8623 g-mL-1. Different cross-reactivities with the closely related pyrethroids,including permethrin, fenpropathrin, cypermetnrin, cyhalothrin and deltamethrin, were conducted, with I50 value of 4.0665, 4.2324, 4.2867, 4.8749 and 8.9791 g-mL-1,respectivity. There was a low cross reactivity for esfenvalerate with an I50 value of 77.3600ug-mL-1. The resultindicated the antibody was practicable to determinate the residues of pyrethroids.2.A direct competitive ELISA (DC-ELISA) was established by using the highly generic antibody against PBA, which was labeled with Horseradish Peroxidase(HRP). TheDC-ELISA protocol was developed for screening pyrethroids on vegetables with the values of detection limit 0.2462~0.7422ug-mL-1, the values of precisioa6.05%~10.87%, and the recovery rate 68.46%~96.10%. The samples of 107 vegetables from Nanjing region were detected with the protocol. Compared the results with Gas Chromatogrphy(GC), the positive rate of the protocol was 8.46%, the false-positive rate was 4.72%. The preliminary application showed the protocol was a time-saving and easily-operating to screen the pyrethrbid residue on vegetables.3.The residue of beta-cypermethrin on vegetables could be removed through different approaches including storage, washing, heating, irradiating with ultraviolet wave, and treating with base or ozone. The results showed that all of them were effective. Thedegradation of the residue by storage and UV-light was a slow process, the removingrate was 28.01% with storage for 72 hour and 27.15% under UV-light for Ihour. The removal of beta-cypermethrin was quickened with the increase of temperature and value of pH, the rate was 77.99% through soaking in 60 C water for 5 minutes and 40.15% under pH11 for Ihour. The removing rate was over 30% through washing with 0.05%detergent. The rate of 50.27% was obtained with ozone for 30 minutes.