Investigation of retention behavior of natural cannabinoids on differently substituted polysaccharide-based chiral stationary phases under reversed-phase liquid chromatographic conditions

Abstract

The growing popularity of cannabis products and recent legalization of cannabis for recreational purposes have contributed to the increase of the demand for analytical methods able to give a detailed characterization of cannabis samples and derivatives. In this context, one of the aspects that is strongly emerging is about the hazardous potential of uncharacterised minor cannabinoids, including chiral ones, for which achiral potency testing methods currently employed do not give any information. For this reason, there is a growing interest towards the development of liquid chromatographic methods for the enantioseparation of cannabinoids. Much work is needed in this field where one of the major limitations is the lack of optically pure standards. This manuscript reports about the chromatographic behavior of five popular cannabinoids (including the cannabichromene racemate, CBC) on nine immobilised polysaccharide-based chiral stationary phases (CSPs) differently substituted, under reversed phase conditions. Results showed that chemo-selectivity of CSPs is not affected by changes in mobile phase composition, in the range of mobile phase investigated. In addition, the presence of electron withdrawing groups on the CSPs systematically leads to shorter retention times compared to when electron donating groups are present. An application of separation of cannabinoids from a real hemp extract on two of the chiral columns employed in this work revealed the presence of both CBC enantiomers in the sample.