Immunoassay Development for the Class-Specific Assay for Types I and II Pyrethroid Insecticides in Water Samples

Five generic haptens of pyrethoid insecticides, which were classified as three types, were designed and synthesized: the first (hapten 1) is for type I pyrethroids without a cyano group, the second (hapten 2 and XQ) for type II pyrethroids with a cyano group, and the third (hapten 4 and 5) for both types of pyrethroids with loss of the ester group. The hapten structures were confirmed by MS and 1H-NMR. Hapten 1 and 2 were conjugated with BSA respectively and haptens 1-5 were conjugated with OVA. Four polyclonal antisera were raised against BSA conjugates including a mixture conjugate, and twenty antibody/coating conjugate combinations were selected for studies of assay sensitivity and specificity for pyrethroids. The study revealed the best combination, which showed equal high sensitivities (I50 is around 0.02 μg mL-1) to both types of pyrethroids. The immunity results suggest that, with a mixture conjugates, a polyclonal antibody against a group of insecticides can be prepared for multi-residue assays.