Electrochemistry; Voltammetry; Amalgam electrode; Drug research

This paper describes voltammetric behavior of 1,4-benzodiazepines (BDZs) on meniscus-modified silver solid amalgam electrode with aim of their determination. Cyclic voltammetry was used for the study of electrochemical behavior (reversibility, adsorption-diffusion process, and charge transfer coefficient) of BDZs. Differential pulse voltammetry was utilized for proposing reaction mechanism, finding supporting electrolyte with optimal pH, and determining diazepam in urine. The pH effect was studied in different media (Britton-Robinson, phosphate, citrate buffer, and 0.1 mol dm-3 NaOH). The calibration dependences exhibited good linearity in the range from 10-7 to 10-4 mol dm-3 under the optimum pH conditions. The advantage of the developed methods was simple, fast, and low-cost procedure for the determination of BDZs. The developed method was successfully used for the diazepam determination in the model sample of urine.