▎ 摘　　要

A new disposable electrochemical sensor for rapid determination of ractopamine (RAC) is developed based on the use of a magnetic screen-printed electrode (MSPE) modified with an iron oxide magnetic nanoparticles doping on reduced graphene oxide (Fe3O4/rGO). Morphology, structure and composition of nanocomposites were characterized by TEM, x-ray absorption spectroscopy (XANES) and x-ray photoelectron spectroscopy (XPS). XANES results indicated that the prepared nanocomposites exhibited the magnetic behavior, and the original structure of Fe3O4 NPs was displayed after being successfully doped on the rGO. XPS was used to confirm the chemical compositions of GO, GO doped with Fe3O4 and Fe3O4/rGO reduced by glucose. The electrochemical and electrocatalytic characteristics of the modified MSPE were recorded using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) and the factors that affected the performance of the sensor were also optimized. The peak currents obtained by DPV increased linearly with the increasing of the concentration of RAC and the sensor had a detection range over the concentration ranges of 0.05-10 and 10-100 mu M, with a detection limit of 13 nM (S/N = 3). Due to the Fe3O4/rGO promoting the electron transfer, and raising the sensitivity of the sensor, the proposed disposable sensor displayed a good sensitivity, stability and reproducibility and robust operation in spiked real pork samples.