Spectrofluorimetric study of the β-cyclodextrin–ibuprofen complex and determination of ibuprofen in pharmaceutical preparations and serum

The inclusion complexation of ibuprofen in β-cyclodextrin (β-CD) has been examined by means of spectrofluorimetry at both acid and alkaline pH. The results suggest that stable 1:1 complexes are formed in both media. The analysis of the pKa values for ibuprofen in both the absence and presence of β-CD (4.12 and 4.66, respectively) suggests that in the inclusion complex the carboxylic group is located outside the cyclodextrin (CD) but interacting with it. Further structural characterization of the complex was carried out by means of am1 semiempiral calculations. Based on the obtained results, a spectrofluorimetric method for the determination of ibuprofen in the presence of β-CD at 10 °C was developed in the range of 4.7–58 μg ml−1. Better limits of detection (1.6 μg ml−1) and quantification (4.7 μg ml−1) were obtained in this latter case with respect to those obtained in the absence of β-CD. The method was satisfactorily applied to the quantification of ibuprofen in pharmaceutical preparations. A novel spectrofluorimetric determination of ibuprofen in the presence of β-CD was also developed for serum samples at concentration levels between 5 and 70 μg ml−1. It uses second-order fluorescence excitation–emission matrices coupled to an algorithm based on self-weighted alternating trilinear decomposition (SWATLD), and avoids resorting to separative instrumental analyses.