Charge-Transfer Complexation for Spectrophotometric Assay of Certain Imidazole Antifungal Drugs

Abstract

A spectrophotometric method is described for the assay of some antifungal agents containing an imidazole ring: clotrimazole, econazole, ketoconazole and miconazole. The method is based on the formation of a charge-transfer complex between the drug as n-electron donor and iodine as [sgrave]-acceptor. The product exhibited two absorption maxima at 290 and 377 nm; measurements are made at 290 nm. Beer's law is obeyed in a concentration range of 1-40 μg/ml. The method is rapid, simple and sensitive and can be applied to the analysis of some commercial dosage forms without interference. A detailed investigation of the formed complex was made with respect to its composition, association constant and free energy change.