Highly Selective and Stable Electrochemical Sensor for Hydrogen Peroxide—Application in Cosmetics Quality Control

Nowadays, electrochemical sensors have become a popular topic in cosmetics quality control. A simple and stable electrochemical sensor for hydrogen peroxide (H2O2) was developed on the basis of a rhodium-modified glassy carbon electrode (Rh/GCE). A quick, one-step, reproducible, and cost-effective electrodeposition procedure was applied to modify GCE with Rh nanoparticles. The sensor shows a high selectivity for H2O2 at a low applied potential of −0.1 V (vs. Ag/AgCl, 3 M KCl), with an excellent stability and good repeatability (RSD = 3.2%; n = 5). The modified electrode Rh/GCE demonstrates a high sensitivity of 172.24 ± 1.95 μA mM−1 cm−2 (n = 3), a linear response to H2O2 between 5 and 1000 µM, and a detection limit estimated to be 1.2 µM. Furthermore, Rh/GCE has been successfully used to measure H2O2 concentrations in hair dye and antiseptic solution, yielding satisfactory recovery rates. These findings highlight the potential of the Rh/GCE for the reliable quantitative detection of H2O2 in complex cosmetics matrices.