Spectrofluorimetric determination of ciclopirox olamine via ternary complex with Tb(III) and EDTA

A highly sensitive and selective spectrofluorimetric method was developed for the determination of ciclopirox olamine in raw material and in dosage forms. The proposed method is based on the formation of a ternary complex with Tb(III) in the presence of ethylenediaminetetraacetic acid. It was found that this complex manifests intense fluorescence at lambda(em) 489 and 545 nm with excitation at 295 nm. Different experimental parameters affecting the fluorescence intensity of the complex were carefully studied and incorporated into the procedure. Under the described conditions, the method is applicable over the concentration range 30-150 and 10-70 ng mL(-1) with minimum detectability of 6.7 and 0.9 ng mL(-1) at lambda(em) 489 and 545 nm, respectively. The mean percentage recovery at lambda(em) 489 and lambda(em) 545 nm ranged between 98.7 and 100.2 for the pure substance, solution, and cream. Relative error of 0.1-0.4% and RDS of up to 0.9% were estimated at lambda(em) 489 and 545 nm. A proposal of the reaction pathway is given.