Hapten synthesis and enzyme-linked immunosorbent assay for phosmet residues: assay optimization and investigation of matrix effects from different food samples.

In this study, a panel of haptens was synthesized for immunoconjugate preparation, and several haptens for heterologous tracer conjugates were also prepared. A highly sensitive polyclonal antibody against the organophosphorus insecticide phosmet was obtained and competitive direct enzyme-linked immunosorbent assays (cd-ELISA) for this pesticide were developed. In the cd-ELISA, the limit of detection (IC(15)) was 0.6 microg kg(-1) and the sensitivity (IC(50)) was 20 microg kg(-1). The suitability of the ELISA for pesticide quantification in peach, apple, orange juice, and apple juice was also studied. Good accuracy and precision were obtained with mean recoveries between 78% and 102.3% and mean coefficients of variation below 13.63%. Validation of the ELISA was conducted by high-performance liquid chromatography. The correlation between the data obtained using the microwell assay and the high-performance liquid chromatography was good (R(2) = 0.9849). The developed immunoassay methods were suitable for the rapid quantitative or qualitative determination of phosmet in food samples.