Interaction of Fluorescein with Felodipine: A Spectrofluorometric and Thermodynamic Study

摘要

The interaction between fluorescein and felodipine (FLD) was investigated by the spectrofluorometric method. The fluorescence of FLD was quenched by fluorescein and quenching is in accordance with the Stern-Volmer relation. The binding constants of fluorescein with FLD were obtained at different temperatures. The binding constant and number of binding sites at different temperatures were calculated yielding the corresponding thermodynamic parameters S, H and G. The distance r between the donor (FLD) and acceptor (fluorescein) molecules was obtained according to the fluorescence resonance energy transfer. The optimum conditions for the fluorometric determination of fluorescein were studied and the quenching method was successfully applied to estimate the fluorescein concentration of the pharmaceutical sample directly.