Electrochemical behaviour of bromazepam and alprazolam and their determination in the pharmaceutical tablets Lexaurin and Xanax on carbon paste electrode

The electrochemical behaviour of 1,4-benzodiazepines (bromazepam and alprazolam) was studied in Britton-Robinson (BR) buffer using cyclic voltammetry and differential pulse voltammetry on carbon paste electrode (CPE). Functional group of benzodiazepines is irreversibly reduced by the help of two electrons and two protons and the electrode process is controlled by adsorption (bromazepam), respectively, by diffusion (alprazolam) on CPE. The optimal conditions were found for their determination in the BR of pH 3 within concentration range from 8 9 10(-7) to 1 9 10(-4) mol dm(-3). Limit of quantification 3.8 9 10(-7) and 4.2 9 10(-7) mol dm(-3) was calculated for bromazepam and alprazolam, respectively. The proposed voltammetric method was applied to analysis of benzodiazepines (BDZs) in the pharmaceutical preparations Lexaurin (R) and Xanax (R) with recovery 94.9 % and relative standard deviation (RSD) 2.21 % for bromazepam and recovery 94.5 % with RSD 2.9 % for alprazolam.