Substitution of Antibody with Molecularly Imprinted Film in Enzyme-Linked Immunosorbent Assay for Determination of Trace Ractopamine in Urine and Pork Samples

Abstract

A new direct competitive enzyme-linked immunosorbent assay (ELISA) with molecularly imprinted film as artificial antibody was developed to detect ractopamine (RAC) in urine and pork samples. The imprinted film was directly synthesized on the well surface of 96-well plate by an organic–inorganic hybrid technology and evaluated by fourier transform infrared (FT-IR), static, and kinetic adsorption experiments. The imprinted film exhibited an antibody-like binding ability and rapid adsorption speed. The established ELISA method gave a good sensitivity (IC₅₀, 15.77 μg L⁻¹) and a low detection limit (IC₁₅, 0.01 μg L⁻¹) for RAC under the optimum conditions, and it was applied to the determination of RAC in urine and pork samples spiked at three levels with recoveries ranging from 77.7% to 108.9% (urine) and from 93.5% to 101.1% (pork). The obtained results, which correlated well with those gained from the traditional high performance liquid chromatography (HPLC) method, demonstrated that the developed ELISA method was reliable for RAC determination in real samples.