Capillary electrophoretic separations of peptides using micelle-forming compounds and cyclodextrins as additives.

The value of electrokinetic capillary chromatography for separating structurally similar model peptides and tryptic digests is demonstrated. The behavior of model peptides in buffer systems containing dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate and two cyclodextrins as additives is described. These additives, under different analytical circumstances, exhibit certain beneficial effects for peptides with similar net charges but different hydrophobicities. Separations of underivatized peptides, utilizing UV detection, are presented. In addition, separation of fluorescent products of peptides derivatized with o-phthalaldehyde, fluorescamine, and a new reagent, 3-(4-carboxybenzoyl)-2-quinolinecarboxaldehyde, are demonstrated and discussed. Beneficial spectroscopic detection effects with cyclodextrin are also noted.