Abstract: Diethylphosphono acetic acid (DPA) was used as a generic hapten in order to generate broad specificity polycolonal antibodies against a group of organophosphorus pesticides. Six New Zealand white rabbits were immunized with immunogens sysnthesised by the mixed-anhydried method and EDC method, the titers of antiserum had reached 25600 and 6400, respectively. The CI-ELISA was conducted with the antiserum, the detection limit for DPA was 3.536ng/mL and the I50 was 0.182μg/mL. The antiserum also showed high affinities to chlorpyrifos, diazinon, omethoate, parathion-ethyl and profenofos, the I50 to these pesticides were 0.12，0.15，0.21，0.88, 0.97 and 2.5μg/mL. It is concluded that this assay is suitable screening tool for quantities and semi-quantities detection of the five organophosphorus pesticides.

Key words: Phosphorous pesticides, Broad specificity antibody, Enzyme linked immunosorbent assay (ELISA)