A comparison of LC and SFC for cellulose‐ and amylose‐derived chiral stationary phases

This paper presents a systematic comparison of liquid chromatography (LC) and supercritical fluid chromatography (SFC) for Chiralcel OD and Chiralpak AD chiral stationary phases (CSPs), performed using various chiral compounds having a known or potential pharmaceutical activity. The chiral recognition mechanisms involved in LC and SFC for the enantiomeric separation of β‐blockers have been studied more particularly. As a general rule, it appears that the presence of polar functions, like primary or secondary hydroxyl or amine functions, may result in marked discrepancies in selectivity between LC and SFC. This result is peculiar to cellulose‐ and amylose‐derived CSPs, for which the interactions involved in chiral recognition mechanism are not always well balanced, contrary to what happens for independent CSPs. In the case of chiral resolution of polar solutes or polymer‐type CSPs, the analyst should try both the LC and SFC techniques to be able to choose the more stereoselective one.