The effect of conductivity tuning in chiral separations by CE; Using hydroxypropyl-beta-cyclodextrin in combination with tetraalkylammonium ions

Different approaches how to handle the electromigration dispersion process that occurs in separation and determination of enantiomers are presented. T he use of cyclodextrins as chiral selectors in resolution enantiomers invol ves the possibility to tune the conductivity of the sample band in order to obtain symmetrical and efficient peaks Determination of impurities that mi grate in the rear part of an overloaded main peak can be accomplished if th e conductivity of the background electrolyte (BGE) is adapted to the conduc tivity of the sample band. This strategy was shown in determination of the content of D-sotalol in a mixture of L and D-sotalol. The efficiency and th e symmetry of the overloaded L-sotalol peak was substantially improved by s ubstitution of tetrabutylammonium ions for tetrapentylammonium ions as cc-i ons in the BGE. In this system it was possible to determine 0.2 % w/w of th e chiral impurity D-sotalol. A resolution model is presented and used quali tatively in the study where the complexation between the tetraalkyllammoniu m ions and the cyclodextrins is taken into account.