CHARGE-TRANSFER COMPLEXATION FOR SPECTROPHOTOMETRIC ASSAY OF CERTAIN IMIDAZOLE ANTIFUNGAL DRUGS

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