Question

Can you distinguish enantiomers from HPLC? If so, how?

Answer 1

On Chiral HPLC one can separate the enantiomers as it has chiral stationary phase which can intereact with the pair of enantiomers differently to get them resolved. One can not use normal HPLC to separate the enantiomers as enantiomers have same physical & chemical properties.

The formation of the diasteromeric complex on equilibration on stationary phase helps to resolve the two enantiomers. The other physiochemical interactions with the stationary phase like hydrogoen bongding, pi-pi intereaction, dipole-dipole interaction, ionic interaction etc. are also involved.

Stationary phase in the chiral HPLC is made of synthetic polymer (methacrylate, polycyclic amine-3), natural polymer (cellulose, amylose, proteins) & small molecule ligands (cyclodextrin-12, crown ether, copper complex-2).

By running chiral HPLC one can calculate the enatiomeric excess which is used to measure the percent purity of the one enantiomer over the other.

%ee = area of enatiomer 1-area of enatiomer 2/area of enatiomer 1 + area of enatiomer 2 x 100

If the standard of each enatiomers is availble one can compare the enatiomers with respect to retention time on the chromatogram.