Liquid Chromatography - Macrocyclic Glycopeptide Phases 2

Vancomycin is very stable with a relatively high sample capacity, and, when covalently bonded silica gel has multiple linkages to the silica gel surface. It can be used as a reversed phase, with mobile phases having a high water content, or, alternatively, as polar stationary phase with a mobile phase of high solvent content (e.g., when used as a reversed phase, strongly polar THF–water mixtures are very effective mobile phases. Conversely, when used as a polar stationary phase, n-hexane–ethanol mixtures are appropriate. Vancomycin has a number of ionizing groups and thus can be used over a range of different pH values (pH 4.0 to 7.0) and exhibit a wide range of retention characteristics and chiral selectivities. Ammonium nitrate, triethylammonium acetate and sodium citrate buffers have all been used satisfactorily with this stationary phase.

 

An example of the use of the stationary phase to separate the enantiomers of 3-methyl-5-phenylhydantoin is shown in figure 50.

 

 

 

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 50. The Separation of the Enantiomers of 3-Methyl-5-Phenylhydantoin Using Polar and Dispersive Interactions