Square wave polarographic and voltammetric analysis of selected electroreducible drugs

Abstract

The square wave polarographic and voltammetric behaviour of the antibiotics chloramphenicol ( I), metronidazole ( II), oxytetracycline ( III), cephalothin ( IV) and trimethoprim ( V), together with the tranquilliser chlordiazepoxide ( VI), has been studied at single growing and stationary mercury drop electrodes. Single drop square wave polarography was used to investigate the contribution of adsorption by interpretation of i p dash t p relationships. A study of the variation of peak current with solution variables such as pH, constitution of supporting electrolyte, concentration of electroactive drug and instrument variables such as square wave frequency, scan speed and accumulation time for those molecules amenable to adsorptive stripping voltammetry has led to optimisation of the reduction signal for analytical purposes using square wave voltammetry at the stationary mercury drop electrode. Detection limits have been found for the drugs in question and are generally of the order of 10 −8-10 −7 M. The use of the automated cell together with rapid-scan square wave voltammetry for the determination of these drugs singly, in formulations and in mixtures with each other was investigated.