Control of enantiomer migration order in capillary electrophoresis separations using sulfobutyl ether...

The control of enantiomer migration order in capillary electrophoresis (CE) by use of sulfobutyl ether beta-cyclodextrin (SBE-beta-CD) was investigated. At high pH, electroosmotic flow (EOF) dominated and the enantiomer most strongly associated with the anionic cyclodextrin was detected last. At low pH (and reversed polarity), EOF was minimal and SBE-beta-CD functioned as a carrier. Under such conditions, the enantiomer migration order for a neutral chiral compound was reversed. Factors involved in optimization (cyclodextrin and organic modifier concentration) were studied. The impact of migration order on quantitation of low levels (below 1%) of one enantiomer in the presence of the other was also investigated. The precision of peak area ratios (minor/major enantiomer) was evaluated for samples of both enantiomers run by each method. The migration of minor before major enantiomer yielded better quantitation precision in each case.