Effect of the crosslinker type on the enantioseparation performance of β-cyclodextrin functionalized monoliths prepared by the one-pot approach

Low column efficiency for enantioseparations in capillary liquid chromatography (CLC) is a major problem commonly encountered with,beta-cyclodextrin (beta-CD) functionalized polymer-based monoliths. In order to investigate the effect of the crosslinker type on enantioseparation performance, three commonly used crosslinkers, i.e. 1,4-bis(acryloyl)piperazine (PDA), ethylene dimethacrylate (EDMA) and N,N-methylenebisacrylamide (MBA), were copolymerized using the one-pot approach with glycidyl methacrylate-mono-6-amino-6-deoxy-beta-CD (GMA-NH2-beta-CD) as functional monomer. The three monolithic columns, including poly(GMA-NH2-beta-CD-co-PDA) and poly(GMA-NH2-beta-CD-co-MBA), as well as the previously reported column poly(GMA-NH2-beta-CD-co-EDMA) were systematically compared with respect to morphology, permeability, beta-CD density, retention mechanism and efficiency. The enantioseparation ability of each column was evaluated using 14 chiral compounds, including mandelic acid derivatives, profens, N-derivatized amino acids, and herbicides, as test substances. The beta-CD-functionalized monolith with MBA as crosslinker was found to exhibit higher polarity, higher column efficiency and better enantioseparation performance than those with PDA or EDMA as crosslinker. (C) 2016 Elsevier B.V. All rights reserved.