An electrochemical sensor based on MgO/ZnO nanocomposite modified carbon paste electrode for toxic heavy metal ions in milk.

In this study, a self-fabricated magnesium oxide/zinc oxide (MgO/ZnO) nanocomposite modified carbon paste electrode (CPE) was synthesized via a hydrothermal method for the electrochemical detection of toxic heavy metals in cow milk. The structural and morphological features of the nanocomposite were confirmed by X-ray diffraction (XRD), UV–visible spectroscopy (UV–Vis), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The electrochemical performance of the modified electrode was assessed using cyclic voltammetry (CV) with potassium ferrocyanide as a redox probe, showing enhanced reversibility and larger electro active surface area compared to single-component ZnO/CPE and MgO/CPE electrodes. Key analytical parameters, including pH, metal ion concentration, deposition potential, and deposition time, were optimized. The MgO/ZnO modified CPE was then applied for the determination of Pb2+ and Cd2+ ions in milk samples using anodic stripping voltammetry (ASV). The sensor exhibited a linear detection range of 100–800 µgL−1, with sensitivities of 0.787 µA µg−1 L-1 for Cd2+ and 0.710 µA µg-1 L-1 for Pb2+, and detection limits of 0.45 µg/L (Cd2+) and 0.142 µg/L (Pb2+). The developed sensor demonstrated excellent sensitivity, selectivity, stability, Specificity, reputability and reproducibility, confirming its suitability for routine monitoring of heavy metals in dairy matrices. These findings suggest that the MgO/ZnO-modified CPE is a promising platform for rapid and reliable detection of toxic heavy metals in milk.