Investigation of diazepam by pulsed rotation voltammetry

Review of Electroanalytical-Based Approaches for the Determination of Benzodiazepines

The benzodiazepine class of drugs are characterised by a readily electrochemically reducible azomethine group. A number are also substituted by other electrochemically active nitro, N-oxide, and carbonyl groups, making them readily accessible to electrochemical determination. Techniques such as polarography, voltammetry, and potentiometry have been employed for pharmaceutical and biomedical samples, requiring little sample preparation. This review describes current developments in the design and applications of electrochemical-based approaches for the determination of the benzodiazepine class of drugs form their introduction in the early 1960s to 2019. Throughout this period, state-of-the-art electroanalytical techniques have been reported for their determination. Polarography was first employed focused on mechanistic investigations. Subsequent studies showed the adsorption of many the benzodiazepines at Hg electrodes allowed for the highly sensitive technique of adsorptive stripping voltammetry to be employed. The development and introduction of other working electrode materials such as carbon led to techniques such as voltammetry to become commonly reported, and the modification of these electrodes has now become the most commonly employed approach using molecularly imprinting and nanotechnology.

Electrochemical behavior and differential pulse polarographic determination of rifampicin in the pharmaceutical preparations

Differential pulse polarographic (DPP) analytical procedure for the rifampicin antibiotic, which can be applied to monitor its synthetic process from the starting antibiotic of rifamycin B or rifamycin SV, has been developed based on the electrochemical reduction of an azomethine group. Rifampicin exhibited a cathodic peak due to the azomethine group in the side chain of 3-[(4-methyl-1-piperazinyl)imino]methyl moiety and another cathodic peak due to the carbonyl group in rifamycin SV by DPP The experimental peak potential shift of an azomethine reduction was -73 mV/pH in the pH range between 3.0 and 7.5, agreeing with involvement of 4 e- and 5 H+ in its reduction. By the cyclic voltammetric(CV) studies, the azomethine and the carbonyl reductions in rifampicin were processed irreversibly on the mercury electrode. The plot of peak currents vs. concentrations of rifampicin ranging 1.0 x 10(-7) M tp approximately 1.0 x 10(-5) M yielded a straight line with a correlation coefficient of 0.9996. The detection limit was 1.0 x 10(-8) M with a modulation amplitude of 50 mV. DPP has been successfully applied for the determination of rifampicin in the pharmaceutical preparations.