Comparison of charge state distribution in commercially available sulfated cyclodextrins used as chiral resolving agents in capillary electrophoresis

The charge state distributions of randomly sulfated cyclodextrins from Sigma–Aldrich and Beckman-Coulter, as well as single isomer sulfated cyclodextrins from TM Chemicals LP were investigated using hydrophilic interaction liquid chromatography (HILIC). A cross-linked diol phase and an unbonded silica phase were used as HILIC stationary phases. Groups of sulfated cyclodextrins with different charge states were resolved from each other, while regioisomers in a charge group were partially separated. A ladder of sulfated cyclodextrins having a charge state distribution from 1 to 14 was prepared and was used to determine the charge state heterogeneity of the commercially available sulfated cyclodextrin samples. Wide charge state and regioisomer distributions are seen for the randomly sulfated cyclodextrins, while HILIC analysis of every single isomer sulfated cyclodextrin sample indicates the presence of a single species.