Determination of β-adrenergic agonists by hapten microarray

The use of highly active β-agonists as growth promoters is not appropriate because of the potential hazard for human and animal health. To investigate the residue level of these β-agonists, hapten microarrays were employed for clenbuterol (CLB), ractopamine (RAC) and salbutamol (SAL) residue analysis. CLB, RAC and SAL conjugates were immobilized on the slides, which were precoated by agarose film to construct hapten microarrays, and then the corresponding monoclonal antibodies of these β-agonists and the standards or samples were introduced for indirect competitive immunoassay. Finally, Cy3-labeled secondary antibody was employed to indicate the antigen–antibody complex. The fluorescence intensity of each spot was imaged and recorded, and the calibration curve of each analyte was obtained by plot fluorescence intensity against different standard concentrations. Compared to the ELISA, the hapten microarray method was more sensitive, which got the detection limits 0.09 μg/L for CLB, 0.50 μg/L for RAC, and 0.01 μg/L for SAL. What's more, with the recovery rate between 96.5% and 106.4%, and the coefficient of variation below 10%, the proposed hapten microarray method was shown to be both quantitative and reproducible.