Highly sensitive electrochemical sensor for the food toxicant Sudan I based on a glassy carbon electrode modified with reduced graphene oxide decorated with Ag-Cu nanoparticles

The authors describe a method for room temperature preparation of reduced graphene oxide (rGO) decorated with Ag-Cu nanoparticles (NPs). The nanocomposite (Ag-CuNP/rGO) was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. A glassy carbon electrode (GCE) modified with this nanocomposite dispersed is shown to be a viable electrode for determination of Sudan I (best at a working voltage of −112 mV vs. Ag/AgCl), with remarkably increased electrochemical response to Sudan I compared to that of a plain GCE. The calibration plot is linear in the 1.0 nM to 10 µM concentration range, with a 0.4 nM detection limit (at a signal-to-noise ratio of 3). The method was successfully applied to the determination of Sudan I in ketchup and chili powder.