Search

Supercritical fluid chromatography (SFC) has proven to be widely applicable for the separation of enantiomers on chiral stationary phases. Many of the chiral selectors utilized in gas and liquid chromatography have also been transferred to SFC. This article provides an overview of the types of separations reported on different classes of chiral stationary phases in SFC and includes comparisons of SFC to other chromatographic techniques. The importance of various chromatographic parameters in obtaining successful enantioseparations in SFC is also discussed.

A comparison of liquid (LC) and sub- or supercritical fluid chromatography (SFC) was performed using naphthylethylcarbamoylated-β-cyclodextrin chiral stationary phases (NEC-CD CSPs). Compounds resolved in the normal-phase, reversed-phase and polar organic modes on the NEC-CD CSPs in LC were also separated on the same columns in SFC with a carbon dioxide-alcohol eluent. Advantages of SFC for chiral separations on these CSPs included simple eluents, rapid optimization of selectivity and improved resolution compared to LC results for the same columns. The effect of alcohol modifier was also investigated and the results provided insights into the chiral recognition mechanisms in SFC. The versatility of the NEC-CD CSPs in SFC was demonstrated by performing separations representative of the three distinct mobile phase modes in LC in a single analysis in SFC.

A method is proposed for the direct enantiomeric analysis of chiral drugs in human serum by HPLC. The method is based on a commercially available β-cyclodextrin bonded phase which incorporates diol as well as cyclodextrin moieties. The proteinaceous components of the serum, which are shown to elute with the void volume, are well separated from the enantiomeric analytes. This allows for the rapid determination of the enantiomeric composition of the drugs.

A significant number of the organic components of foods, flavorings, pharmaceuticals, and pesticides are chiral molecules (Ariens, 1988). The role of stereochemistry in biological processes was first recognized more than 100 years ago by Pasteur and van’t Hoff’Le Bel (Pasteur, 1901). Much of the stereoselectivity of these chemicals has remained shrouded in mystery, however, because techniques for chiral separations were not well developed. The fact that enantiomers exhibit identical physical and chemical properties in an achiral environment renders their separation extremely difficult.