Evaluation of chiral separation ability and separation principle of β-cyclodextrins-based supramolecular deep eutectic solvent in capillary electrophoresis

A series of supramolecular deep eutectic solvents (SURPADESs) consisting of β-cyclodextrin (β-CDs) (β-CD, HP-β-CD, M-β-CD) and l-lactic acid were synthesized and employed as chiral selector to investigate their chiral selectivity in capillary electrophoresis. Key elements influencing the separation efficiency, such as the ratio of HBA/HBD of SUPRADESs, the concentration of SUPRADESs, and buffer pH were thoroughly examined and deliberated upon. Under the optimum enantioseparation conditions, three SUPRADESs systems showed markedly enhanced chiral separation of model chiral drugs, in comparison with single CDs and dual chiral selectors composed by adding its two constituents CDs and l-lactic acid separately. Additionally, the Benesi-Hildebrand plot was employed to determine the binding constant for the inclusion complexes, and molecular modeling was used to explore the mechanisms behind the increased chiral separations in SUPRADESs. Results demonstrated that SUPRADESs exhibit significantly improved chiral selectivity efficiency by enhancing the host-guest encapsulation of the constituent β-CDs, which is attributed to the increased hydrogen bonding and hydrophobic interactions between chiral analytes and β-CDs and HBD of SUPRADESs. This work provides a possibility for SUPRADESs to be used as chiral selection in CE.