Square wave voltammetric determination of valproic acid in pharmaceutical Preparations


Abstract: The electrochemical behavior of valproic acid (VAL) was investigated using square wave voltammetry, cyclic voltammetry, and sampled direct current polarography and a new square wave voltammetric method was developed for determination of VAL in pharmaceutical preparations. VAL showed two reduction peaks at about --0.2 V and --0.8 V vs. Ag/AgCl 3 M KCl with a hanging mercury drop electrode in 0.05 M pH 3.3 Britton--Robinson (BR) buffer. These peaks were named peak I and peak II, respectively. The types of limiting current of both peaks were determined as diffusion controlled based on cyclic voltammetry studies. A linear calibration graph was obtained in the range 1.46 $\times $ 10$^{-4}$--1.0 $\times $ 10$^{-3}$ M. The limit of detection (LOD) and limit of quantification (LOQ) were 1.09 $\times $ 10$^{-4}$ M (21.05 $\mu $g/mL) and 1.10 $\times $ 10$^{-4}$ M (144.20 $\mu $g/mL), respectively. Recovery studies for the accuracy of the method were performed by adding known amounts of VAL and it was found to be 109.67 $\pm $ 4.85{\%}. The proposed method was successfully applied to pharmaceutical products on the market.

Keywords: Square wave voltammetry, drug determination, valproic acid, valproate analysis, carboxylic acid electrochemical reduction

Full Text: PDF