Chiral analysis by multivariate regression modeling of spectral data using cyclodextrin guest–host complexes—Methods for determining enantiomeric composition with varying chiral analyte concentration

The determination of the enantiomeric composition of samples by chemometric modeling of UV spectral data was investigated for samples of phenylalanine and norephedrine over a total concentration range of approximately 6–9 mM using β-cyclodextrin as a chiral auxiliary. Three different methods of compensating for variation in total analyte concentration were studied, and the results of all three are compared. This study shows that total analyte concentration need not be held constant during the analysis, as in previous studies, but can be allowed to vary within a given range and still give acceptable results. The choice of method depends on the analyte, and even raw data analysis without adjustment for concentration may be sufficient in some cases. Structural differences in the analytes may contribute to the degree of success for each of the three methods.