A novel nail polish/graphite/nickel nanoparticles-based disposable screen-printed sensor for enhanced voltammetric...

A low-cost electrochemical sensor based on a graphite screen-printed carbon electrode modified with nickel nanoparticles was developed for the sensitive determination of mefenamic acid (MFA), an emerging environmental contaminant due to its persistence and incomplete removal in wastewater treatment, which may lead to endocrine-disrupting effects in aquatic systems. The incorporation of nickel nanoparticles into the graphite-based ink significantly increased the electroactive surface area and enhanced electron transfer kinetics, resulting in improved analytical performance. Morphological and structural analyses confirmed the successful integration of nickel nanoparticles into the electrode matrix. Electrochemical characterization using cyclic voltammetry and electrochemical impedance spectroscopy demonstrated higher faradaic currents and lower charge transfer resistance compared to the unmodified electrode. Under optimized conditions, differential pulse voltammetry provided a well-defined oxidation signal for mefenamic acid, with a linear range from 0.5 to 12.20 µmol L⁻¹, a limit of detection of 69.12 nmol L⁻¹, and a sensitivity of 0.434 µA L µmol^- 1. The sensor exhibited good repeatability (RSD = 3.85%), satisfactory long-term stability (88% signal retention after 30 days), and excellent recovery (96-99%) in tap and river water samples. The proposed platform combines sensitivity, reliability, low cost, and operational simplicity, demonstrating strong potential for on-site environmental monitoring of mefenamic acid.