Ultrasensitive and Specific Detection of Salbutamol in Swine Feed, Meat, and Urine Samples by a Competitive Immunochromatographic Test Integrated with Surface-Enhanced Raman Scattering

Abstract

Salbutamol (SAL), a kind of β-agonist which can enhance the lean meat-to-fat ratio, has been inhibited as an additive used in animal feeds for livestock production in many countries due to its harmful effect to the consumers. In this study, an ultrasensitive and specific competitive immunochromatographic test (ICT) integrated with surface-enhanced Raman scattering (SERS) for the detection of SAL was described. The immunoprobe was prepared by immobilizing polyclonal antibody against SAL on the surface of Au@Ag nanoparticles in which the Raman reporter (4-mercaptobenzoic acid, MBA) had been sandwiched. After ICT procedures, the specific SERS signals generated from MBA on the test line of the ICT strip were measured for the quantitative determination of SAL. The assay was completed in 15 min. The IC50 and the limit of detection (LOD) values of the assay for SAL were 0.028 ng mL−1 and 3.0 pg mL−1, respectively. There was no cross-reactivity (CR) of the assay with other three β-agonists (clenbuterol, phenylethanolamine A, and ractopamine), showing high specificity of the assay. Spiking experiments indicated that the average recoveries (n = 3) of SAL from swine feed, meat, and urine samples were in ranges of 98.4–105.2 % with the relative standard deviations (RSDs) of 1.7–7.8 %. The results demonstrated that the proposed ICT was a feasible method for ultrasensitive and specific detection SAL in swine feed, meat and urine samples, and could be extended for the detection of other target analytes.