Determination of zeranol and its metabolites in bovine muscle and liver by a chemiluminescence enzyme immunoassay: compared to an ultraperformance liquid chromatography tandem mass spectroscopy method.

A chemiluminescent enzyme immunoassay (CLEIA) was compared to an ultraperformance liquid chromatography tandem mass spectroscopy (UPLC-MS/MS) procedure for the analysis of zeranol and its metabolites in bovine tissue samples. Apparent recoveries from fortified samples by both methods were comparable at 0.5-4.0 µg/kg and a significant correlation was obtained. For CLEIA analysis, hapten mimicking the analyte was first synthesized and conjugated with the carrier protein bovine serum albumin as the immunogen to produce monoclonal antibody. The obtained antibody showed extensive cross-reactivity toward zeranol metabolites (zearalanone). The limit of detection of CLEIA and UPLC-MS/MS was 0.05 µg/kg and 0.5 µg/kg, respectively. Recoveries of both methods for fortified samples were higher than 75.0% with the coefficient of variation less than 15%. These results indicated that the combination of screening with CLEIA and confirmation with UPLC-MS/MS for zeranol and its metabolites would be a reliable method for a large number of bovine samples.