Study of quinine hydrochloride detection using boron-doped diamond electrodes

This study investigates the electrochemical properties of quinine hydrochloride (QH) using boron-doped diamond (BDD) electrodes. The redox behavior of QH was analyzed and compared in phosphate buffer solution (PBS) and potassium perchlorate (KClO4) electrolyte, observing an increase in current response with hydrogen-terminated BDD (H-BDD) electrodes. A cyclic voltammogram of QH in 0.1 M PBS and 0.1 M KClO4 shows a reduction peak at −1.14 V (vs. Ag/AgCl). The scan rate dependence was examined to understand the reduction mechanism involving two electrons. A linear calibration curve was noted from 2 μM to 25 μM range (R2 = 0.99) with detection limits of 0.18 μM in PBS and 0.16 μM in KClO4. The BDD electrodes demonstrated good selectivity in tonic water with sharp oxidation potentials for QH, confirming their stability for QH detection.