Terms normal phase and reverse phase for chiral columns

[smansani42]

Hello everyone,
This is my first post on chromatography forum, and I have a question about chiral columns. I am working on a chiral column, and in the column manual it's mentioned that it is a reverse phase column. This column has ionic, hydrophilic, and hydrophobic interactions, and my question is why it's called reverse phase column when all kinds of interactions are involved. In a few postings in this forum, they mentioned that normal phase and reverse phase terms are not used for chiral columns. If not, why it's given in the column manual as a reverse phase column. And also in the column manual, they suggested not to increase the organic phase higher than 15%. Thanks in advance for your reply.

[tom jupille]

It's a case of loose terminology. "Normal phase" simply means that the column (stationary phase) is more polar than the solvent (mobile phase). "Reversed phase" is, as you might expect, the reverse: the solvent is more polar than the column.

These gross oversimplifications imply certain *primary* retention mechanisms (reversed-phase, for example, is arguably driven more by sample-solvent interactions, while normal-phase is driven more by sample-column interactions). Once you can get compounds retained, the actual selectivity (the ability to discriminate between similar compounds) is affected strongly (in the case of chiral compounds, actually, entirely controlled) by secondary interactions.

[DR]

^... which means that it is still a function of analytes having different partition coefficients and that chiral column interactions result in an exploitable difference in partition coefficients between enantiomers. (to keep it all in the simplest possible vein - right?)

[smansani42]

Thanks for your reply,,,, Mr. Tom Jupille