Chiral HPLC versus chiral SFC: Evaluation of long-term stability and selectivity of Chiralcel OD using various eluents

The long-term stability of Chiralcel OD columns under varying HPLC and SFC conditions was evaluated. Two new columns from the same supplier lot were procured, and one was installed in an HPLC system, and the other was installed in an SFC system. Enantiomeric mixtures of trans-stilbene oxide and carbobenzyloxy phenylalaninol were repeatedly injected in both systems over several days. For HPLC, hexane was the primary solvent used, along with IPA EtOH, MeOH/IPA, or EtOH/TFA modifier. Carbon dioxide was the primary SFC solvent, together with the similar modifiers as the HPLC. Column performance was monitored by measuring resolution, theoretical plate number, and α between enantiomeric peaks. It was observed that, when the eluent strengths were adjusted to provide comparable retention times, the Chiralcel OD gave superior enantiomeric resolution when used in the SFC than the HPLC. Equilibration in between solvents was faster with SFC. The columns were demonstrated to be quite stable in both systems.