Diethylphosphono acetic acid （DPA） was used as a current hapten to generate broad specificity polycolonal antibodies against a group of organophosphorus pesticides. Six New Zealand white rabbits were immunized with immunogens synthesized by the active ester method （AEM） or 1-ethyl-3-（3-dimethylaminopropyl）-carbodimide method （EDC）. The titers of antisera reached 25 600 by AEM and 6 400 by EDC, respectively. Polyclonal antibodies raised against DPA were screened and selected for the competitive indirect enzyme-linked immunosorbent assay （CI-ELISA）. A CI-ELISA for DPA was developed with a detection limit of 3.536 ng mL^-1and an I50 value of 0.182 μg mL^-1. The assay specificity was evaluated by obtaining competitive curves for several structurally related compounds as competitors. The antiserum showed high affinities to chlorpyrifos, diazinon, omethoate, parathion-ethyl and profenofos with I50 of 0.12, 0.15, 0.21, 0.88, 0.97 and 2.5 μg mL^-1, respectively. The results indicate that the assay could be a screening tool for quantitation and semiquantitation determination of the above former five organophosphorus pesticides.
LIU Xian-jin YAN Chun-rong LIU Yuan YU Xiang-yang ZHANG Cun-zheng
High-affinity and specific monoclonal antibodies against cadmium-ethylene diamine tetraacetic acid(EDTA)complex have been produced using the hybridoma technique.A hapten was synthesized and characterized by Fourier Transform Infrared Spectroscopy(FT-IR)and UVVis.Competitive enzyme-linked immunosorbent assay(ELISA)for quantitative detection of cadmium in aqueous sample was developed.The monoclonal antibody with high level of binding affinity for Cd-IEDTA-BSA and high specificity for soluble Cd-EDTA complex showed less than 0.99%cross-reactivity with other 11 metals.The limit of detection was 0.10μg·L^(-1),and the effective linear range was 10^(-1)-10^(3)μg·L^(-1).The intra-and inter-assay coefficient variations were 1.5%-6.3%and 3.2%-7.4%,respectively.The spike recovery in different water samples were between 98.5%and 110.3%.The detection limit of this assay was well below the allowable concentration of cadmium(3μg·L^(-1)),and the working range was wider than that of other methods which showed the range of 2.19-86.38 and 0-10^(3)μg·L^(-1).The competitive ELISA established in this paper was sensitive and accurate in the screening of cadmium in aqueous samples.The results will lay a solid foundation for construction of an immunoassay kit for cadmium.
