Simultaneous determination of hydroquinone, catechol, and resorcinol with an electrochemical sensor based on poly-l-valine, multi-walled carbon nanotubes, and Co3O4 nanoparticles

An electrochemical sensor based on carboxylated multi-walled carbon nanotubes (c-MWCNT), Co₃O₄ nanoparticles (Co₃O₄NP), and poly-L-valine (PolyVal) was fabricated for the simultaneous determination of hydroquinone (Hyd), catechol (Cat), and resorcinol (Res). The optimum amounts of modification materials on the electrode surface and the optimum pH of the working solution were determined to achieve the best electrode performance. Under optimum conditions, individual determination of each analyte was performed in the presence of other analytes. Simultaneous determination of Hyd, Cat, and Res was also carried out, and the performance characteristics of the electrode, such as working range, LOD, reusability, reproducibility, and selectivity, were evaluated for each analyte. In the simultaneous determination for Hyd, Cat, and Res, the linear working ranges were 5-260 µM, 5-280 µM, and 31-550 µM, and the LOD values were 3.62 µM, 2.57 µM, and 7.97 µM, respectively. The presented electrochemical sensor was successfully applied to the simultaneous determination of Hyd, Cat, and Res in tap water and river water, and satisfactory recovery values were obtained.