Complexation study and spectrofluorimetric determination of pipemidic acid with γ-cyclodextrin

The fluorimetric characteristics of pipemidic acid (PIPE) have been investigated. It has been proven that the fluorescence emission band of pipemidic acid at 439 nm is significantly intensified in the presence of gamma-cyclodextrin. The inclusional complexation between the antibacterial pipemidic acid and gamma-cyclodextrin (gamma-CD) has been studied. A 1:1 stoichiometry of the complex was established and its association constant was calculated by a nonlinear regression method, monitoring the changes in the fluorescence signal of pipemidic acid in the presence of gamma-CD. According to the results obtained, a spectrofluorimetric method for the determination of PIPE has been proposed. The best limits of detection and quantification were obtained in presence of gamma-CD, in acidic media. The dynamic range of the method was comprised between 0.18 and 1.40 mu g/ml.