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

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 mu g L-1. The IC50 value of the dipstick ELISA using reflectance detection was 8.8 mu g L-1 with a detection limit of 0.3 mu g L-1. The recoveries of parathion-methyl from spiked lettuce and rice samples using the dipstick ELISA ranged from 89% to 106%.