Development of Square Wave Voltammetric Method for the Electrochemical Determination of Pregabalin as Pregabalin-Cu(II) Complex Using Graphite Electrode

Abstract

In the present study, a square wave voltammetric (SWV) method was developed for the determination of pregabalin (PREG) in commercial drugs and biological samples as PREG-Cu(II) complex using graphite working electrode. A well-defined voltammetric signal of the complex was observed at nearly – 200 mV, by using Britton Robinson supporting electrolyte (B-R) at pH 7.5. There were some analytical conditions that have been evaluated through this research such as accumulation time and potential, scan rate, amplitude, frequency, and stirring rate to obtain a good voltammetric peak and high current without any overlap. In addition, some metal ions as potential interferences; such as Zn(II), Ni(II) and Cd(II) have been added at different concentrations to evaluate their effects on the voltammetric signal for PREG-Cu(II) complex. The SWV performance was investigated by monitoring parameters such as calibration curve, detection limit, reproducibility, stability and recovery. The calibration curve was studied over the range 5.0 ´10^-8–1.0 ´10^-6 mol L^-1of (PREG) and 5.0 ´ 10^-5 mol L^-1 of copper ion (n=8, r² = 0.99), yielded a linear relationship between voltammograms and complex concentrations. The sensitivity of SWV method was evaluated by calculating the detection limit which was found to be 6.5´10^-9 mol L^-1. The reproducibility, stability and recovery were studied for 5.0 х10^-7 mol L^-1of (PREG) and 5.0 х 10^-5 mol L^-1 of copper ion, yielded a relative standard deviation (RSD%) that was calculated to be 0.4% and good stability for the voltammetric signal, while the recovery was recorded to be 93±1.23%. The analytical voltammetric technique (SWV) was applied to determine PREG-Cu(II) complex in pharmaceutical capsules and biological fluids, specifically urine and plasma, where it gave recoveries of 90±1.0%, 89±1.23% and 86±1.23%, respectively.