Supramolecular interaction of metoprolol with β-cyclodextrin: Spectroscopic characterization and analytical application

In this work, the inclusion complex of metoprolol with β-cyclodextrin was prepared and investigated using various spectroscopic techniques. The aqueous solution of the inclusion complex was examined using UV-visible, fluorescence spectroscopy, and 1 HNMR, whereas the solid physical mixing was investigated by utilizing Fourier transform infrared. Confirmation of the existence of an inclusion complex is achieved through the observation of alterations in spectroscopic properties. Both 1:1 and 1:2 stoichiometry a host–guest interaction was formed between metoprolol and β-cyclodextrin. The constants that represent the inclusion the interaction was determined to be K1=9.09 × 10 −4 μM −1 and K2=1.96 × 10 −6 μM −1 by using typical double reciprocal graphs. The parameters affecting the inclusion complex formation were investigated and optimized. Based on remarkable increase on the fluorescence intensity, spectrofluorometric method for determination of metoprolol in pharmaceutical formulation was developed. The fluorescence intensity of metoprolol was measured at 297 nm, after excitation at 223. Under the optimum conditions, linear relationship in concentration range of 0.35–1.7 μM, with correlation coefficient of 0.9944, was obtained. The limit of detection has been shown as 0.11 μM, while the limit of quantification was shown as 0.34 μM. The proposed approach was successfully utilized to analyze the drug in its pharmaceutical formulation.