Voltammetric determination of antifungal agents in pharmaceuticals and cosmetics using boron-doped diamond electrodes
Ketoconazole and ciclopirox olamine remain two most popular antifungal agents. Determinations of these substances were carried out by means of a square-wave voltammetry method (SWV) and a boron-doped diamond electrode (BDD). The electrochemical oxidation of ketoconazole and ciclopirox olamine demonstrated irreversible peaks of oxidation for both the substances studied at 0.59 V and at 0.66 V, respectively. Examining the influence of the scan rate has allowed to demonstrate that the currents registered remain diffusion-controlled. This paper has established the optimal oxidation conditions for both compounds studied. The pH value together with the nature of the supporting electrolyte and the SWV characteristic parameters were analysed. Under optimized conditions for ketoconazole and ciclopirox olamine oxidation, the influence of concentration over the value of the current registered was examined. A linear dependence was achieved in the range between 2.87 × 10−7 mol L−1 and 3.13 × 10−6 mol L−1 for ketoconazole and from 2.53 × 10−5 mol L−1 to 4.19 × 10−4 mol L−1 for ciclopirox olamine. The calibration curves achieved demonstrated high correlation outcomes. The obtained limit of detection reached 8.29 × 10−8 mol L−1 for ketoconazole and 6.66 × 10−6 mol L−1 for ciclopirox olamine. The recovery, precision and accuracy of the recommended methods were examined as well. The measured precision has not exceeded 0.95% for ketoconazole and 2.87% for ciclopirox olamine. The aforementioned methods were applied successfully with regard to the ketoconazole and ciclopirox olamine analyses in several pharmaceutical dosage forms, e.g. tablets, cream and anti-dandruff shampoo. The elaborated methods remain accurate, which is acknowledged by the recovery values obtained ranging from 97.67% to 99.99%. The proposed procedures were compared with pharmacopoeial reference methods. Statistical t-Student and F-Snedecor tests were conducted as well in order for the developed methods to be contrasted with pharmacopoeial reference methods.