Development of a sensitive monoclonal antibody-based ELISA for the detection of clenbuterol in animal tissues

A specific monoclonal antibody (mAb) against clenbuterol, with cross-reactivities less than 0.01% for all test compounds except salbutamol (6.4%), was produced with hybridoma technology. The mAb originated from immunogen of clenbuterol-human serum albumin was combined with coating antigen of salbutamol-ovalbumin to develop a heterologous enzyme-linked immunosorbent assay (ELISA). This assay shows very high sensitivity with IC50 of 0.3 ng/ml and LOD of 0.1 ng/ml when it was run in 0.01 M PBS (pH 7.5). Clenbuterol was spiked in chicken and pork samples and after a simple extraction procedure the extracts at appropriate dilution were analysed by ELISA. Satisfactory results were obtained by both intra-assay, with average recoveries of 81-102% and coefficient variations (CVs) of 3-12%, and inter-assay, with average recoveries of 77-95% and CVs of 5-13%. The survey results of ELISA and HPLC for some real world tissue samples were consistent. It suggests that the mAb-based ELISA will be a feasible quantitative/screening method for clenbuterol residue in animal tissues.