Sensor based on nickel oxide modified electrode for concurrent detection of vitamin C and paracetamol

This study presents a nickel oxide-modified screen-printed carbon electrode (NiO/SPCE) for the simultaneous electrochemical detection of vitamin C (VC) and paracetamol (PA) in pharmaceutical formulations. NiO was electrodeposited by the potentiostatic method on the surface of SPCE atom-by-atom in a dilute solution (0.1 μM Ni2+). Physicochemical characterisations confirmed uniform NiO deposition, enhancing electron transfer kinetics and active surface area. The modified electrode exhibited distinct oxidation peaks at 0.24 and 0.48 V for VC and PA, respectively, with corresponding peak currents of 6.40 and 8.23 μA. Differential pulse voltammetry demonstrated excellent linear detection ranges of 200–893 μM for VC and 1–4.46 μM for PA, with detection limits of 15.9 and 0.254 μM, respectively. Stability and reproducibility tests yielded relative standard deviations of ≤1.31% for VC and ≤1.60% for PA over eight successive measurements. Interference studies confirmed selectivity, with negligible effects from ions and sugars at 100- and 50-fold concentrations, respectively. These findings underscore the NiO/SPCE’s potential as a robust, sensitive, platform for pharmaceutical quality control and therapeutic monitoring applications.