An enzyme immunoassay for the anabolic agent zeranol.

A competitive enzyme immunoassay (EIA) for the detection and quantitation of zeranol has been developed. The assay involves the use of excess second antibody adsorbed onto the walls of a microtitration plate well. Enzyme-labelled zeranol, prepared by the N-succinimidyl ester method, and standard or samples are added to the wells followed by zeranol-specific monoclonal antibody. The working range of the EIA is between 10 and 800 pg/well with a limit of detection of 10 pg/well (CV less than or equal to 10%). Comparison of radioimmunoassay with the EIA gave a correlation coefficient of 0.99. This EIA offers an alternative to the well-documented radioimmunoassay with regard to sensitivity, specificity and precision.