Highlighting the role of the hydroxyl position on the alkyl spacer of hydroxypropyl-β-cyclodextrin for enantioseparation in capillary electrophoresis

This work investigates the resolving power of 2,3-dihydroxypropyl-beta-CD (2,3-DHP-beta-CD) and 3-hydroxypropyl-beta-CD (3-HP-beta-CD) as chiral mobile phase additives (CMPAs) using CE. The effects of experimental parameters (CD concentration, buffer pH, and buffer concentration) on enantiorecognition were investigated. More than 20 basic chiral drugs were resolved with satisfactory enantio selectivity. Comparison with 2hydroxypropyl-beta-CD (2-HP-beta-CD) showed that one or both of the two new chiral selectors show enhanced enantiorecognition for several molecules with bulky substitutes, such as Zopiclone and Mianserin, however, 2-HP-beta-CD has higher enantiorecognition for most of the analytes. Further studies on the structures of analytes and CMPAs showed that the OH moiety on the propyl spacer plays an important role in the separation of some chiral drugs