A monoclonal antibody-based sensitive enzyme-linked immunosorbent assay (ELISA) for the analysis of the organophosphorous pesticides chlorpyrifos-methyl in real samples

Chlorpyrifos-methyl hapten, O-methyl-O-(3,5,6-trichloro-2-pyridinyl)-N-(2-carboxyethyl)-phosphoramidothionte (H1), was synthesized and conjugated with bovine serum albumin (BSA) and ovalbumin (OVA) by the active ester method. Then H1–OVA conjugate was used as coating antigen, while H1–BSA conjugate was used as immunogen for producing monoclonal antibody. After optimisation, a monoclonal antibody-based effective competitive indirect enzyme-linked immunsorbent assay (ELISA) was developed and applied for determination of chlorpyrifos-methyl with a novel combination of antibody/antigen, I₅₀ of which was 75.22 ng/ml, limit detection (LD) was 0.32 ng/ml, and there was relative high cross-reactivity (CR) only with chlorpyrifos (1.4%), and CRs with other tested pesticides were all below 1% and regarded as negligible. The recoveries obtained by standard chlorpyrifos-methyl addition to real samples, including grape, Chinese cabbages, water and soil were all from 82.4% to 110.2%. Therefore, the optimised ELISA might become a convenient and satisfied analytical tool for monitoring chlorpyrifos-methyl residues in agriculture ecosystem.