Unexpected carbonate salt formation during isolation of an enantiopure intermediate by supercritical fluid chromatography.

•Resolution of enantiomers by supercritical fluid chromatography.•Turning an inefficient chromatographic method to a sustainable one.•Recycling of mobile phase components.•Awareness of equilibria in a CO2-based mobile phase.•Formation of carbonate salt, due to increased apparent pH in the mobile phase.