Development of a cu-doped electrode from pepper stalk waste for the sensing naproxen

Naproxen (2-(6-methoxynaphthalen-2-yl) propanoic acid, NPX) is a pharmaceutical substance used widely as an effective anti-inflammatory drug. The detection of NPX is crucial as prolonged exposure can pose significant risks to both human health and environment. In this study, a novel electrochemical sensor was developed using electrode made from pepper-stalk extract waste, doped with Cu nanoparticles, to detect the NPX. Scanning electron microscopy (SEM) results confirmed the formation of a three-dimensional porous carbon structure doped with Cu nanoparticles. The electrochemical performance of the fabricated electrode was assessed using cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS), by varying scan rates, pH levels, and NPX concentration. Electrochemical results showed that the sensor exhibited high selectivity for NPX, with a limit of detection (LOD) of 2.3 × 10 −8 M and limit of quantification (LOQ) of 7.8 × 10 −8 M. The electrode demonstrated excellent repeatability, with a relative standard deviation of 1.3 % and stability of 93 % over a period 30 days. These findings indicate that the pepper stalk-derived carbon electrode doped with Cu nanoparticles offers enhanced electro-conductivity, electro-activity, and selectivity for the determination of NPX when compared to the unmodified form.