Electrochemical Sensor Based on Multiwall Carbon Nanotube-Paste Electrode for Determination of Promethazine in Pharmaceutical Formulations and Blood Plasma

A multi-walled carbon nanotube modified paste electrode (MWCN-PE) was used for determination of promethazine (PMZ) in drug formulations and blood plasma by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. Results revealed that the MWCN-PE shows an electrocatalytic activity toward the anodic oxidation of PMZ by a marked enhancement in the current response in buffered solution at pH 5.0.  At the MWCN/CPE, the anodic peak potential of PMZ was shifted by 28.0 mV to more negative potential in comparison with bare carbon paste electrode. The detection limit for this method was 0.025 µmol L-1. Results indicated that the modified electrode could be employed for the determination of promethazine hydrochloride in pharmaceutical formulations and plasma samples.