[Chiral separation of dipeptides by capillary electrophoresis]

Peptides are increasingly used as pharmaceutical agents. Many small peptides are the essential compounds in biological systems. Direct chiral separation of dipeptide derivatives using 9-(2-carbazole) ethyl chloroformate (CEOC) as the derivatizing agent by capillary electrophoresis (CE) with beta-cyclodextrin (beta-CD) and sodium deoxycholate (SDC) as chiral selectors has been developed. It has been well recognized that the combination of the binary selectors can enhance the selectivity and resolution instead of either beta-CD or SDC alone. The molar ratio of the binary chiral selectors, the buffer concentration and pH of Tris-H3PO4, organic modifier were studied and optimized. Complete chiral separations for 14 dipeptide derivatives using beta-CD and SDC as binary chiral selectors were obtained. The results indicated that each pair of D/L chiral resolution was more than 3.63, and the highest resolution for Gly-Ala was 43.14.