Spectroscopic investigations on the inclusion interaction between hydroxypropyl-β-cyclodextrin and bupropion

The inclusion interaction of hydroxypropy1-beta-cyclodextrin (HP-beta-CD) with bupropion (BUP) was followed by UV and nuclear magnetic resonance (NMR) spectroscopy. The main factors affecting the inclusion interaction were discussed in detail. The inclusion complexation behavior of hydroxypropy1-beta-cyclodextrin with bupropion was studied in aqueous buffer solution of pH = 5 at room temperature. According to the continuous variation Job's method applied to spectroscopy measurements, a 1:1 stoichiometry has been proposed for the complex formed. The formation constant of the complex (log K) was 3.63 +/- 0.01. Based on the significant enhancement of absorption intensity of bupropion, a sensitive spectrophotometric method was elaborated for the determination of active substance in bulk aqueous solution in the presence of HP-beta-CD. At optimized experimental conditions, a linear relationship between the absorbance and concentration of BUP is observed in the range of 3-40 mu g ml(-1) with limit of detection of 0.32 mu g ml(-1) and correlation coefficient of 0.9998. The proposed method was applied to the determination of BUP in pharmaceutical products and the results were satisfactory in comparison with the official method. (C) 2011 Elsevier B.V. All rights reserved.