Bilinear least squares (BLLS) and molecular fluorescence in the quantification of the propranolol enantiomers

The quantification of mixtures of (R)- and (S)-propranolol (PRO) in the pure form and in the pharmaceutical preparations is described. The methodology is based on chiral recognition of propranolol by formation of an inclusion complex with β-cyclodextrin (CD), a chiral auxiliary, in the presence of 1-butanol. The excitation–emission fluorescence surface and second-order multivariate calibration such as bilinear least squares (BLLS) and parallel factor analysis (PARAFAC) were used in the model development. BLLS performed better than PARAFAC, presenting relative mean error in the order of 3.5%, analytical sensitivity of 0.07% and 0.08%, detection limit of 0.23% and 0.28% and quantification limit of 0.71% and 0.84% for the pure form and pharmaceutical preparations, respectively. These results indicate that the proposed methodology can be an alternative for the determination of propranolol enantiomeric composition.