Development of a dipstick enzyme‐linked immunosorbent assay for the organophosphorus insecticide parathion‐methyl

Summary In our previous study, polyclonal antibodies against the organophosphorus insecticide parathion‐methyl were obtained and competitive enzyme‐linked immunosorbent assays (ELISAs) for this pesticide were developed. In this study, using these antibodies and an enzyme tracer, a direct competitive ELISA for parathion‐methyl in dipstick format was developed. The dipstick ELISA using Immunodyne membrane as a solid support, allowed the quick visual detection of parathion‐methyl in concentrations above 10 μ g L −1 . The IC 50 value of the dipstick ELISA using reflectance detection was 8.8 μ g L −1 with a detection limit of 0.3 μ g L −1 . The recoveries of parathion‐methyl from spiked lettuce and rice samples using the dipstick ELISA ranged from 89% to 106%.