Enzyme linked immunosorbent assay (ELISA) for the quantitative analysis of diethylstilbestrol (DES) residues in the muscle of Trionyx sinensis

Based on the antigen-antibody reaction, diethylstilbestrol (DES) in the muscle of Trionyx sinensis is bound by the sheep antibodies that are directed against rabbit IgG (anti DES antibody) in the reagent box. After a washing step the DES enzyme conjugate is added, which is bound by the remaining free antibody binding sites. With the enzyme substrate, the colorless chromogen converts into a blue product. The measurement is made photometrically at 450 nm. The absorption is inversely proportional to the DES concentration in the sample. The mean lower detection limit of this method is about 0.0125μg/kg. The mean recovery rate is 74.8% and the coefficients of variation is 1.763～3.084%. This method is rapid, sensitive and reliable. It is available for sensitive detection of DES residues.