Enantiomeric purities are determined for binary mixtures of D-pseudoep
hedrine with the L-enantiomer and with the (+)- and (-)-ephedrines in
bulk solutions using circular dichroism (CD) detection in the visible
range. The molecules are individually derivatized by ligand exchange w
ith tartrate in the first coordination sphere of Cu(II) metal complexe
s. Chiral-chiral interactions, after substitution, are specific enough
to uniquely discriminate among all four enantiomers using spectra for
the mixed complexes. A univariate calibration model is used to predic
t enantiomeric purities for mixtures of the pseudoephedrines, and mult
ivariate models are used for all three binary mixtures. Results for en
antiomeric ratios that lie in the mole fraction range 0.95-1.00 are an
improvement over current methods. Achiral mesotartrate is the optimum
host ligand to use for the analysis of binary mixtures of diastereois
omers.