Supramolecular Study on the Interaction Between Ofloxacin and Methyl β-Cyclodextrin by Fluorescence Spectroscopy and its Analytical Application.

The supramolecular interaction of ofloxacin (Oflo) and methyl β-cyclodextrin (Mβ-CD) has been examined by UV-vis, IR and fluorescence spectroscopy. The formation of inclusion complex has been confirmed based on the changes of the spectral properties. The results showed that Mβ-CD reacted with Oflo to form an inclusion complex. The Oflo and Mβ-CD complex formed a host-guest complex in 1:1 stoichiometry and inclusion constant (K = 7.8 × 10(-3) L mol(-1)) was ascertained by the typical double reciprocal plots. Furthermore, the thermodynamic parameters (∆H°, ∆S° and ∆G°) associated with the inclusion process were also determined. In addition, solid inclusion complex was synthesized. Based on the significant enhancement of the fluorescence intensity of Oflo produced through complex formation, a simple, accurate, rapid and highly sensitive spectrofluorometric method for the determination of Oflo in pharmaceutical formulation was developed. The measurement of relative fluorescence intensity was carried out at 497 nm with excitation at 296 nm. The factors affecting the inclusion complex formation were studied and optimized. Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.9995) were in the concentration range of 50-350 ng/mL for spectrofluorimetry. The limit of detection (LOD) was 11.5 ng/mL. The proposed method was successfully applied to the analysis of Oflo in pharmaceutical preparation.