Manganese dioxide Nanorods/electrochemically reduced graphene oxide nanocomposites modified electrodes for cost-effective and ultrasensitive detection of Amaranth.

A novel manganese dioxide nanorods-electrochemically graphene oxide nanocomposites modified glassy carbon electrode (MnO2NRs-ErGO/GCE) was developed for the rapid and sensitive detection of Amaranth in foodstuffs. The morphology, structure and composition of MnO2NRs, ErGO, and MnO2/ErGO were characterized by SEM and XRD. The electrochemical behavior of Amaranth on the bare GCE, ErGO/GCE, and MnO2NRs-ErGO/GCE were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The voltammetric conditions (including pH, scan rate, accumulation potential as well as time) were optimized systematically. Due to large electrochemical active area and low charge transfer resistance, the MnO2NRs-ErGO/GCE exhibited a great enhancement effect on the oxidation of Amaranth, and significant increased the oxidation peak current ipa (approximately 38-fold increase compared to that of bare GCE). Under the optimum voltammetric conditions, the ipa varied linearly with Amaranth concentration in the range of 0.02 μM-10 μM, and 10 μM-400 μM with a low detection limit of 1.0 nM (S/N = 3). Moreover, satisfactory results were obtained in the analysis of real samples. Together with the merits of rapidness, cost-effectivity, high sensitivity and selectivity, the result suggests the proposed MnO2NRs-ErGO/GCE have broad application prospects on the sensitive detection of Amaranth in various real samples.