Host-guest inclusion complex of mesalazine and β-cyclodextrin and spectrofluorometric determination of mesalazine.

Abstract

The supramolecular interaction of mesalazine (MSZ) and β-cyclodextrin (β-CD) has been examined by ultraviolet-visible (UV-vis) light, infra-red (IR) light and fluorescence spectroscopy. The formation of an inclusion complex has been confirmed based on the changes of the spectral properties. MSZ-β-CD host-guest complex was formed in (1:1) stoichiometry and the inclusion constant (K = 1.359 × 10(2) L mol(-1) ) was ascertained by typical double reciprocal plots. Furthermore, the thermodynamic parameters (ΔG°, ΔH° and ΔS°) of (MSZ-β-CD) were obtained. Based on the remarkable enhancement of the fluorescence intensity of MSZ produced through complex formation, a simple, accurate, rapid and highly sensitive spectrofluorometric method for the determination of MSZ in aqueous solution in the presence of β-CD was developed. The measurement of relative fluorescence intensity was carried with excitation at 330 nm and emission 493 nm. All variables affecting the reactions were studied and optimized. Beer's law was obeyed in the concentration range 0.1-0.45 µg/mL. Absorbance was found to increase linearly with increasing concentration of MSZ, which is corroborated by the calculated correlation coefficient values of 0.99989. The molar absorptivity, Sandell's sensitivity, detection and quantification limits were calculated. The validity of the described methods was assessed, and the method was successfully applied to the determination of MSZ in its pharmaceutical formulation. In addition, a solid inclusion complex was synthesized by co-precipitation method.