Principles and Practice of Chromatography - Chromatography Applications > Liquid Chromatography Applications > Analysis of β-blockers > Page 96


to 1.85 min. to 2.80 min.
k1 0.78 k1 1.57
k2 1.32 k2 2.13
a 1.69 a 1.35
R 2.18 R 3.0


Courtesy of ASTEC Inc.


Figure 54 The Separation of the Enantiomers of 3-Methyl-5-Phenylhydantoin Using Polar and Dispersive Interactions


It follows that the remaining dominant retentive forces will be polar or ionic in nature. In the second case, the mobile phase is predominantly water and thus provides very strong polar interactions with the solute but very weak dispersive interactions. It also follows, that the retention forces of the stationary phase, in this case, will be dominantly dispersive in nature. This demonstrates the very useful selective flexibility of Vancomycin. By adjusting the mobile phase composition, selectivity can be made to depend largely on dispersive interactions (hydrophobic) or, alternatively, to depend largely on polar interactions (hydrophilic).