Flow injection chemiluminescent competitive immunoassay for the β-adrenergic agonist salbutamol using carboxylic resin beads and enzymatic amplification

A simple, rapid and sensitive competitive immunoassay for the p-adrenergic agonist salbutamol (SAL) was developed with flow injection chemiluminescence (FI-CL) detection. The method was based on immobilizing coating-antigen on carboxylic resin beads and introducing the second antibody tagged with horseradish peroxidase (HRP) into the CL reaction of luminol-PIP-H2O2. The carboxylic resin beads were creatively applied for amplifying signals by carrying more coating-antigen through the chemical bonds between functional groups. With a competitive format, the salbutamol in solution competed with the coating-antigen for the limited binding sites of the antibody. Then the second antibody labeled with HRP was simply immobilized and an enzyme-enhanced CL emission was obtained due to the catalysis of HRP for the CL reaction. Under the optimal conditions, the CL intensity was linearly related to the concentration of salbutamol in the range of 0.5-100 ng mL(-1) with a detection limit (3 sigma) of 0.15 ngmL(-1). This immunosensor exhibited favorable stability, specificity and reproducibility, and was applied to practical samples with satisfactory results. This immunosensing strategy would be of great value in other food additive residues detection. (C) 2015 Elsevier B.V. All rights reserved.