Quantitative detection of β2-adrenergic agonists using fluorescence quenching by immunochromatographic assay

beta(2)-Adrenergic agonists are banned in China and other areas in the world. In this study, a novel method was developed to quantitatively detect beta(2)-adrenergic agonists. The clorprenaline (CLP)-bovine serum albumin (BSA) conjugate is mixed with a BSA-fluorescent microsphere (FM) complex and sprayed on a nitrocellulose membrane as the test line; a goat-anti-mouse antibody is mixed with a BSA-fluorescent microsphere (FM) complex and sprayed on a nitrocellulose membrane as the control line. If the target molecule is absent in the sample, the colloidal gold-monoclonal antibody will bind to the CLP-BSA conjugate coated on the test line, and the colloidal gold quenches the fluorescent microspheres, so that no fluorescent signal develops in the test line, indicating a negative result. The target molecule present in the sample at a cutoff level or higher binds to the colloidal gold-monoclonal antibody in the ELISA well. The colloidal gold-monoclonal antibody (Au-mAb) does not bind to the CLP-BSA conjugate coated on the test line. The fluorescent signal developed in the test line indicates a positive result. The limit of detection (LOD) of the immunochromatographic assay test strip was 0.12 ng mL(-1) when the antibody amount was 0.8 mu g mL(-1) with a detection time of 15 min. The immunochromatographic assay test strip could simultaneously detect five beta(2)-adrenergic agonists, including clorprenaline, bambuterol, terbutaline, clenbuterol, and salbutamol. When spiked swine urine samples (5.0 ng mL(-1) and 10.0 ng mL(-1)) were tested by the novel immunoassay, the recovery was 39.00 +/- 3.0 and 32.00 +/- 2.0, respectively.