Once again, the ratio of diastereomers is the same as that of the original enantiomers. High-pressure liquid chromatography has been used in a similar manner and has wider applicability.210 The direct separation of enantiomers by gas or liquid chromatography on a chiral column has also been used to determine optical purity.
Other methods212 involve isotopic dilution, kinetic resolution, C NMR relaxation rates of diastereomeric complexes, and circular polarization of luminescence.