MnO2-Co3O4@RGO hybrid nanocomposite-modified carbon paste electrode for sensitive electrochemical detection of hydrogen peroxide in food and edible-oil matrices.

Repeated heating of cooking oils promotes lipid oxidation and the formation of reactive oxygen species (ROS) and other oxidation products, including hydrogen peroxide (H2O2). Excessive ROS generation can disrupt cellular redox homeostasis and contribute to oxidative stress, which is associated with cellular damage and biological processes implicated in carcinogenesis. Consequently, reliable methods for monitoring H2O2 in food and cooking oils are of interest for assessing oxidative changes in these matrices. In this work, a non-enzymatic electrochemical sensor was developed for the rapid and sensitive direct determination of H2O2 in food and oil samples. A carbon paste electrode was modified with a hybrid nanocomposite comprising MnO2 and Co3O4 nanostructures supported on reduced graphene oxide (RGO) nanosheets to construct an efficient electrochemical sensing interface. The structural, morphological, and electrochemical characteristics of the synthesized materials and modified electrodes were investigated using transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Following optimization, the MnO2-Co3O4@RGO-modified electrode exhibited enhanced electrocatalytic activity toward the H2O2 oxidation and was evaluated by chronoamperometry (CA), achieving a detection limit of 0.03 µM and a wide dynamic linear range of 0.1-1800 µM. Furthermore, the sensor exhibited good selectivity toward H2O2 in the presence of common interfering species and high sensor surface stability. Thus, its practical applicability was evaluated using H2O2-spiked burger, salami, and cheese samples and repeatedly heated palm-oil samples, with satisfactory recoveries obtained. Accordingly, the newly developed MnO2-Co3O4@RGO-modified electrode provides a simple, cost-effective, and efficient platform for non-enzymatic H2O2 determination, with potential applications in monitoring oxidative changes in cooking oils and selected food matrices.