The separation was carried out under two conditions, the first used pure ethanol as the mobile phase, which is strongly dispersive, and in the second, the mobile phase that contains 90% of water. In the first case, the ethanol provides strong dispersive interactions in the mobile phase which would significantly exceed any dispersive interactions involved with the stationary phase. Consequently, the remaining dominant retentive forces will be polar or ionic. In the second case, the mobile phase is predominantly water and thus provides strong polar interactions with the solute but weak dispersive interactions. It also follows, that the dispersive forces will dominate in the stationary phase. These two examples demonstrate the useful flexibility of Vancomycin.
Another macrolytic glycopeptide used in chiral chromatography is the amphoteric glycopeptide Teicoplanin which is commercially available under the trade name of CHIROBIOTIC T.
A, B, C and D are inclusion cavities. Molecular weight 1885. Chiral
centers 20, Sugar moieties 3, and R is CH3-decanoic acid
Courtesy of ASTEC Inc.
Figure 51. The Proposed Structure of Teicoplanin
