Powerful Analytical Platform for Diazepam Determination in Pharmaceuticals and Alcoholic Drinks Based on Batch Injection Analysis Coupled with Adsorptive Stripping Voltammetry

Abstract

The presented study focuses on the development and optimization of a powerful electroanalytical platform for the direct quantification of diazepam (DZP). This innovative approach integrates a batch injection analysis (BIA) system with a screen-printed electrode arrangement employing square-wave adsorptive stripping voltammetry (SWAdSV). The BIA-SWAdSV method underwent a comprehensive evaluation, wherein various experimental and instrumental parameters were systematically examined in detail. Beneficial analytical performance for detecting DZP was attained in Britton-Robinson buffer with pH 6.0, with an amplitude of 75 mV, a frequency of 10 Hz, a deposition potential of –1.2 V, a deposition time of 150 s, an injection volume of 75 µL, a dispensing rate of 7 µL/s, and without stirring during the deposition step. Under these conditions, the proposed BIA-SWAdSV method demonstrated an adequately broad linear concentration range from 5 to 40 µM (R2 = 0.997) with a micromolar limit of detection of (2 µM) and a satisfactory precision (RSD = 5%). The practical applicability of the newly-established and powerful analytical protocol was confirmed through the analysis of pharmaceuticals and a "fortified" sample of an alcoholic drink (rum) associated with potential criminal activities involving DZP abuse.