Electrodeposition of Cobalt Oxides on Carbon Nanotubes for Sensitive Bromhexine Sensing

Abstract

We develop an electrochemical sensor for the determination of bromhexine hydrochloride (BHC), a widely use mucolytic drug. The sensor is prepared by electrodeposition of cobalt oxides (CoOx) on a glassy carbon electrode modified with carboxylated single-walled carbon nanotubes (SWCNT). A synergistic effect between CoOx and SWCNT is observed, leading to a significant improvement in the BHC electrooxidation current. Based on cyclic voltammetry studies at varying scan rates, we conclude that the electrochemical oxidation of BHC is under mixed diffusion–adsorption control. The proposed sensor allows the amperometric determination of BHC in a linear range of 10–500 µM with a low applied voltage of 0.75 V. The designed sensor provides reproducible measurements, is not affected by common interfering substances, and shows excellent performance for the analysis of BHC in pharmaceutical preparations.

Complexation of gallic acid with calcium: electrochemical, potentiometric, and UV-VIS studies

“…It can be seen that calcium chloride showed no oxidation peak, however gallic acid showed two oxidation peaks at the potential E = 0.14 V (A1) and E = 0.55 V (A2) which correspond to the oxidation of 4-and 5-hydroxyl groups of gallic acid. 18 A differential pulse voltammogram of a solution containing gallic acid and calcium chloride in a 1 : 2 molar ratio revealed one pronounced oxidation peak at the potential E = 0.07 V (A1), and one oxidation peak at the potential E = 0.46 V (A2) indicating gallic acid oxidation in a complex. 19 These results reveal that under the used experimental conditions formation of a gallic acid complex with calcium occurred and that differential pulse voltammetry identies this complex formation quite well.…”