Preparation of MnO₂ nanorods-reduced graphene composite modified electrodes and application in detection of amaranth

MnO₂ nanorods-reduced graphene composite modified glassy carbon electrode (MnO₂ NRs-ErGO/GCE) was prepared for the detection of amaranth using electrochemical reduction method. The surface morphology and crystal structure of the modified materials were characterized by SEM and XRD. The electrochemical behavior of amaranth on the bare electrode, ErGO/GCE and MnO₂ NRs-ErGO/GCE modified electrodes were investigated by cyclic voltammetry, respectively. The determination conditions (including pH value, accumulation potential, and accumulation time) were optimized systematically. The results show that MnO₂ NRs-ErGO increases the electrochemical active area of GCE and improves the electrochemical oxidation reaction of amaranth significantly. Under the optimum detection conditions, the peak current is found to be linear with amaranth concentrations in the range from 2.0×10^-8-1.0×10^-5 mol/L and 1.0×10^-5-4.0×10^-4 mol/L with a low detection limit of 1.0×10^-8 mol/L. The satisfactory results are obtained in the analysis of actual beverage samples by using the proposed modified electrode.