Some thoughts on the coupling of dissimilar chiral columns or the mixing of chiral stationary phases for the separation of enantiomers

Consideration of some basic aspects of the separation of enantiomers on chiral stationary phases suggests that the coupling of dissimilar chiral columns to afford a broad-spectrum screen for the separation of otherwise pure enantiomers cannot be recommended. However, this arrangement can sometimes be useful for the separation of enantiomers in complex mixtures. An analysis of various arrangements is discussed, including tandem column arrangements containing dissimilar chiral packings, columns containing mixed packings or mixed selectors, and the use of columns containing selectors of varying degrees of enantiopurity.