Switched voltammetric determination of ractopamine by using a temperature-responsive sensing film.

This study describes an electrochemical sensor for the animal growth promoter ractopamine. The method is based on the use of a glassy carbon electrode (GCE) modified with a temperature-responsive sensing film composed of reduced graphene oxide, C60 fullerene, and the temperature-sensitive polymer poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMEO2MA). The modified GCE was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. A large oxidation peak current can be observed (maximum typically at 0.57 V vs. Ag/AgCl) when the temperature is raised to above the lower critical solution temperature of PMEO2MA. This peak disappears at lower temperature. Under optimum conditions, the sensor has a detection range for ractopamine from 0.1 to 3.1 μM, with an 82 nM detection limit. The method was successfully applied to the determination of ractopamine in spiked pork samples. Graphical abstract Schematic presentation of the reversible, temperature-controlled "on/off" electrochemical behavior of ractopamine at a glassy carbon electrode modified with a film composed of reduced graphene oxide (rGO), C60 fullerene and the poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMEO2MA).