Some of the most extensive and versatile chiral stationary phases (CSPs) are those based on polysaccharide derivatives (cellulose and amylose) coated onto macroporous silica. Each derivative can exhibit subtly different enantioselectivity for a variety of chiral compounds. Chiral column switching is a very useful analytical tool and ideally suited to these CSPs since they are all used with isopropanol-hexane or ethanol-hexane mixtures, with small additions of acid or base modifiers where appropriate. The technique lends itself to rapid method development where automated overnight runs can be set up to scout for a column and find separation conditions for racemic compounds. The usefulness and potential of chiral column switching using twelve different CSPs arranged in two banks of six columns is illustrated with several chiral molecules. Examples where peak reversal has occurred are highlighted to show the advantages this presents the analyst in final quantitation and enantiomeric excess determination. When scale-up is a consideration the main priority is to achieve high selectivity. Chiral column switching can be used to great effect to search for a column that will fulfil this need. This optimised separation can then be translated to a comparable preparative chiral column for isolation of milligram quantities of each enantiomer.
