Enantioseparation of aromatic dipeptides using carboxymethyl-beta-cyclodextrin polymer as chiral selector by capillary electrophoresis

Chiral separation of peptides is of interest because of the different biolo gical activity of enantiomers. in this report, several underivatized dipept ides with benzene moieties were optically resolved by employing carboxymeth yl-beta-cyclodextrin polymer (CM-beta-CD polymer) as chiral selector. The e ffects of different cyclodextrin types, selector concentration, buffer pH, and organic additive were examined. Selector concentration and buffer PPI p layed significant roles in resolution. Enantioseparation was found to be ne gatively influenced by adding the organic additive into running buffer and even completely lost at the organic additive content of 16%. It was also no ted that the dipeptides with short chain in the vicinity of the second chir al carbon atom showed better chiral resolution by using CM-beta-CD polymer than by using either carboxyethyl-beta-CD or succinylated-beta-CD. Simultan eous chiral separation of a mixture of DL-Ala-DL-Phe and DL-Leu-DL-Phe was also obtained using 27 mg/ml CM-beta-CD polymer in the running buffer at pH 5.12.