Use of charged and neutral cyclodextrins in capillary zone electrophoresis: Enantiomeric resolution of some 2-hydroxy acids

Enantiomers of racemic 2-hydroxy acids, namely 2-phenyllactic, 3-phenyllactic, mandelic, m-hydroxymandelic, p-hydroxymandelic and 3,4-dihydroxymandelic acid, were resolved by capillary zone electrophoresis. The separation was achieved by using the background electrolyte with addition of cyclodextrins. The effects of the type of cyclodextrin, the pH of the electrolyte and the shape of analyte compounds on the migration time and resolution were studied. Good resolution was obtained with background electrolytes in the pH range 5-7, supplemented with 2-hydroxypropyl, 6(A)-methylamino- and 6(A),6(D)-dimethylamino-?-cyclodextrin.