Voltammetric Determination of Diazepam on Antimony Film Screen- Printed Electrode in Pharmaceutical Formulations

Background: Diazepam belongs to the group of 1,4-benzodiapines. It is used for the treatment of anxiety, convulsions and as muscle relaxants. The presence of a 4,5-azomethine group enables its electrochemical detection. Introduction: A screen-printed electrode modified with antimony film was used for the determination of diazepam in pharmaceutical preparations. Methods: Electrode modification was done by ex-situ deposition of antimony on a commercially available screen-printed electrode. Parameters affecting the electroanalytical response of the sensor, such as deposition potential, deposition time, and antimony concentration, were examined and optimized. The modified electrode showed enhanced electroactivity for diazepam reduction compared to the unmodified electrode. Under optimal conditions, linear sweep voltammetry was used for the determination of the analyte. Results: The sensor showed linear dependence in the range from 0.5 to 10 μmol/L, the correlation coefficient was 0.9992. The limit of detection was 0.33 μmol/L, the corresponding limit of quantification was 1.08 μmol/L. The modification enabled the determination of diazepam in the presence of oxygen. Conclusion: The modified electrode was used for the determination of diazepam in tablets. Results confirmed the applicability of the electrochemical sensor.