Magnetic separation of clenbuterol based on competitive immunoassay and evaluation by surface-enhanced Raman spectroscopy

The elimination of beta-agonist has attracted considerable interest due to its harmfulness to human health when it existed in pork. Here, a strategy based on immuno-magnetic nanoparticles has been successfully developed for the selective and successive magnetic separation of two kinds of beta-agonists, clenbuterol (CL) and salbutamol (SAL). The calibration curve of competitive immunoassay was determined for the estimation of the final concentration of targets after the separation, in which the limit of detection (LOD) and half maximal inhibitory concentration (IC50) were about 17 fg mL(-1) and 193 pg mL(-1), respectively. The specific interaction between the target and the complementary antibody attached to Fe3O4@Au nanoparticles resulted in the aggregation of Fe3O4@Au nanoparticles carried with targets. The magnetic collection of the aggregation of Fe3O4@Au nanoparticles decreased the concentration of targets significantly. The results revealed that the final concentration of remaining targets was lower than the LOD. This strategy was employed to separate CL and SAL molecules in mixed solutions simultaneously or successively with high efficiency. The results demonstrate that it provides a selective and effective approach for the removal of harmful residues in practical samples.