DEVELOPMENT OF A MAGNETIC PARTICLE-BASED ENZYME-IMMUNOASSAY FOR THE QUANTITATION OF CHLORPYRIFOS IN WATER

A competitive enzyme immunoassay for the quantitation of chlorpyrifos in water that utilizes amine-terminated superparamagnetic particles as the solid phase to covalently attach mouse monoclonal anti-chlorpyrif os antibodies was developed. Specificity studies indicate that the mon oclonal antibody can distinguish chlorpyrifos from its major degradati on products, including 3,5,6-trichloro-2-pyridinol, and structurally s imilar pesticides. The immunoassay has an estimated limit of detection of 0.10 ng/mL in water and compares favorably with traditional chroma tographic methods when water samples are analyzed by both methods (r = 0.985). Within- and between-assay percent coefficient of variation va lues are <13%, and recovery of chlorpyrifos from water averaged 97% ac ross the range of the immunoassay method.