Development of an Indirect Enzyme-Linked Immunosorbent Assay for the Organophosphorus Pesticide Paraoxon-Methyl

In the present study, the synthesis of hapten for the organophosphorus (OP) pesticide paraoxon-methyl was developed, with a spacer arm (aminocarboxylic acid) attached at the aromatic ring. It was conjugated to bovine serum albumin (BSA) for use as an immunogen and to ovalbumin (OVA) for coating antigen for ELISA testing. Rabbits were immunized with the immunogen and two polyclonal antisera were produced and screened against the coating antigen using competitive indirect enzyme-linked immunosorbent assay (ELISA). For application to textile samples, the influence of several factors such as organic solvent, ionic strength, and pH on the ELISA results were studied. Under optimized conditions, the quantitative working range was 0.012-1.158 mu g/mL with a limit of detection (LOD) of 0.005 mu g/mL and the IC50 was 0.115 mu g/mL. There was negligible cross reactivity (CR) with other OP pesticides. The recoveries obtained by standard paraoxon-methyl addition to the different textile samples such as cotton, wool and muslin delaine were all from 86.0% to 108.0%. Therefore, the optimized ELISA may become a new convenient and economical analytical tool for monitoring paraoxon-methyl residues in textile samples.