A perspective on enantioselective chromatography by comparing ultra-high performance supercritical fluid chromatography and normal-phase liquid chromatography through the use of a Pirkle-type stationary phase

Since their discovery, the Pirkle-type chiral stationary phases, and in particular the Whelk-O1, have been used in a large number of applications and theoretical studies. Although they can be used in many elution modes, their main field of application is in normal phase liquid chromatography and more recently in supercritical fluid chromatography. In this review, we tried to compare the two techniques using the Whelk-O1 stationary phase as a trait d'union. The main milestones obtained in the last decades of research in enantioselective chromatography and possible lights and shadows of the two techniques have been described. There is still a long way to go to achieve the full potential in the field of enantioselective separations, and especially ultra-high supercritical fluid chromatography, given its great potential, is a technique still to be improved.