Electrochemical Detection of Melatonin at Nano-Sized Highly Boron-Doped Diamond Electrode

This work investigates the electrochemical oxidation of melatonin at boron-doped diamond electrodes and demonstrates the significant enhancement in the detection of melatonin using highly boron-doped diamond nanopowder (h-BDD). Employing differential pulse voltammetry, Tween-coated h-BDD modified screen-printed electrodes (Tween/h-BDD/SPE) showed two linear response ranges for melatonin: 0.057–10 and 10–200 μM, with sensitivities of 390 ± 36 and 72.2 ± 3.4 μA mM –1 , respectively, and a detection limit (3S b /m) of 0.017 μM. The Tween/h-BDD/SPE demonstrated good selectivity against common interferences such as tryptophan, serotonin, lactate, cytidine, cytosine, and urea. The analytical utility of Tween/h-BDD/SPE was validated by quantifying melatonin in commercial pharmaceutical tablets, achieving close to 100% recoveries.