Electrochemical Determination of Promethazine Hydrochloride Using Carbon Paste Electrode Modified with Activated Carbon and Silver Nanoparticles

In this work, an electrochemical sensor was developed for the determination of promethazine hydrochloride (PMZ), an antihistamine used to relieve the symptoms of allergies. The sensor was prepared using a carbon paste electrode (CPE) modified with activated carbon (AC) and silver nanoparticles (AgNPs) described as CPE/AC/AgNPs. The analytical response obtained with CPE/AC/AgNPs was 88% higher compared to unmodified CPE. The optimization of experimental conditions contributed to increasing the sensitivity of the proposed electrochemical sensor. The followed experimental conditions were optimized: the proportion of graphite, AC, and AgNPs was 55/25/20 (% m/m), respectively, with 0.05 mol L phosphate buffer solution (PBS) at pH 7.00 as support electrolyte. Under optimized conditions, a linear range from 5-40 µmol L was obtained for PMZ with a limit of detection (LOD) of 1.30 µmol L-1 and a limit of quantification (LOQ) of the 4.20 µmol L-1. The determination of PMZ in Phenergan® tablets showed recovery values between 98.4 and 102.2%, which indicates that the CPE/AC/AgNPs can be used as a viable alternative to the determination of the promethazine in pharmaceutical samples.