Use of the new, single-isomer, hexakis(2,3-diacetyl-6-O-sulfo)-α-cyclodextrin in acidic methanol background electrolytes for nonaqueous capillary electrophoretic enantiomer separations

The new, single-isomer, sulfated α-cyclodextrin, the sodium salt of hexakis(2,3-diacetyl-6-O-sulfo)-α-cyclodextrin (HxDAS), was used for the first time in acidic methanol background electrolytes (BGEs) to separate the enantiomers of weak base analytes by nonaqueous capillary electrophoresis (NACE). The concentration dependence of the effective mobilities and separation selectivities followed trends similar to those observed earlier in acidic methanol background electrolytes with heptakis(2,3-diacetyl-6-O-sulfo)-β-cyclodextrin (HDAS) and octakis(2,3-diacetyl-6-O-sulfo)-γ-cyclodextrin (ODAS). In general, interactions between the weak base analytes and HxDAS were weaker than with HDAS and ODAS. For some of the weak base analytes, separation selectivities observed in acidic aqueous and acidic methanol background electrolytes were complementary to each other, permitting the eventual separation of enantiomers that could not be achieved otherwise.