Capillary electrophoretic separation of weak base enantiomers using the single-isomer heptakis-(2,3-dimethyl-6-sulfato)-beta-cyclodextrin as resolving agent and methanol as background electrolyte solvent

The sodium salt of the single-isomer, heptakis-(2,3-dimethyl-6-sulfato)-bet a-cyclodextrin (HDMS-beta CD) was used as resolving agent in the capillary electrophoretic (CE) separation of weak base enantiomers in pure methanol b ackground electrolytes (BEs). According to the requirements of the charged resolving agent migration model of CE enantiomer separations (CHARM model), a high buffer-capacity, low pH methanolic BE was created from 25 mM phosph oric acid and 12.5 mM NaOH. In this BE, the solubility of HDMS-beta CD was as high as 50 mM, permitting the realization of very high separation select ivities and short separation times for the fully protonated weak base enant iomers. (C) 1998 Elsevier Science B.V. All rights reserved.