Non-enzymatic determination of hydrogen peroxide in milk samples using Graphite oxide/Nafion/Azure A modified electrode

A novel non-enzymatic electrochemical sensor was developed with high selectivity and sensitivity for detecting biologically significant hydrogen peroxide (H2O2). The sensor utilized an electrode modified with graphite oxide/Nafion/Azure A (GO/Nf/AzA) fabricated by simple chemical adsorption method. The incorporation of AzA into the GO/Nf matrix was verified through UV-Vis and FTIR spectroscopy. Electrochemical investigations via cyclic voltammetry and differential pulse voltammetry elucidated the modified electrode's properties. Optimization of experimental parameters, including pH and scan rates, enhanced its electrochemical behavior. Cyclic voltammetry analysis revealed an apparent electron transfer rate constant (Ks) of 1.14 cm/s and a charge transfer coefficient (alpha) of 0.74. Compared to the bare graphite electrode, the modified electrode exhibited significantly higher current densities in response to H2O2 with reduced overvoltage. The reduction peak currents for H2O2 demonstrated a linear correlation with concentrations ranging from 1.3 x 10-6 M to 3.6 x 10-3 M, with a detection limit of 4.3 x 10-7 M (S/N = 3). Notably, the proposed modified electrode displayed excellent sensitivity and selectivity, presenting a promising avenue for H2O2 determination. In amperometric methods, it showcased stable and rapid responses, indicating potential for application in flow system analysis. Real sample analysis involving two distinct milk samples validated the electrodes' good recovery capabilities.