Electrochemical Detection of Melatonin in the Presence of Dopamine on a Ce-Doped Poly(bromocresol purple)-Modified Electrode

In this study, bromocresol purple was electropolymerized on the surface of a pencil graphite electrode (PGE) and electrochemically doped with cerium (Ce) nanoparticles. The Ce-doped poly(bromocresol purple) (Ce/PBCP)-modified PGE was characterized using energy dispersive X-ray spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The prepared Ce/PBCP electrode was investigated for the electrochemical determination of melatonin in the presence of dopamine. The electrochemical activity of the Ce/PBCP electrode was compared with that of undoped PBCP, Ce/PGE, and bare PGE. The peak potential and peak current for melatonin oxidation were +800 mV and 820 μA cm–2, respectively. The detection limit of melatonin was 0.038 μM, and the Ce/PBCP electrode exhibited high activity in the presence of interfering species. In addition, the use of a Ce/PBCP electrode for detecting melatonin in a terebinth sample, a real food sample, was also investigated, and the produced electrode demonstrated high performance.