Electrochemical detection of ractopamine based on a molecularly imprinted poly-o-phenylenediamine/gold nanoparticle-ionic liquid-graphene film modified glass carbon electrode

An electrochemical sensor for sensitive detection of ractopamine (RAC) was fabricated by using molecularly imprinted polymer (MIP) incorporation with graphene (GR), ionic liquid (IL) and gold nanoparticle (AuNPs) nanocomposites. The AuNPs-IL-GR nanocomposite was utilized to improve the electrochemical response while MIP served as a recognition element. The MIPs were prepared by electropolymerization of o-phenylenediamine (oPD) on the AuNPs-IL-GR nanocomposite modified electrode. The resulting sensor was studied with respect to its response to hexacyanoferrate as a probe and characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was used to investigate the electrochemical behaviors of the proposed sensor in a phosphate buffer solution. Under optimal conditions, the peak current was linear to RAC concentration in the range from 10 mu g L-1 to 5000 mu g L-1, with a low detection limit of 0.46 mu g L-1 (S/N = 3). The electrochemical MIP-sensor was applied to the determination of RAC in swine urine samples and satisfactory results were obtained.