Extractive Spectrophotometric Determinations of Clotrimazole in Formulations

Abstract

Four simple sensitive and reproducible visible spectrophotometric methods (A–D) for the determination of clotrimazole (CTZ) in bulk samples and pharmaceutical formulations are described. Methods A, B and C are based on the formation of ion-association complexes between CTZ and tropaeolen-000 (Tp000, λ_max 480 nm), supracen violet 3B (SV3B, λ_max 560 nm) or wool fast blue BL (WFB, λ_max 580 nm). Method D is based on the formation of a molecular complex between CTZ and cobalt thiocyanate (CTC, λ_max 600 nm). Regression analysis of Beer's plots showed good concentration ranges: 1.0–6.0 μg/mL for methods A, B and C and 1.25-7.5 μg/mL for method D. No interference was observed from the usually existing additives in pharmaceutical formulations and the applicability of the methods was examined by analysing cream and powder containing CTZ. Relative standard deviations were typically ≤ 0.33%. Recoveries were ≥ 99.5%.