Principles and Practice of Chromatography - Chromatography Applications > Liquid Chromatography Applications > Analysis of β-blockers > Page 93

The separation of the diastereomers formed by reacting the reagents with some chiral drugs is shown in figure 51. The column was the Intersil ODS 80A, 15 cm long, 4.6 mm I.D., packed with 5 mm particles. The largest peak in the chromatogram was the reagent itself. Peak 1 was (R)-(+)-Propanolol, peak 2 was (S)-(-)-Propanolol, peak 3 (R)-(+)-Alprenolol and peak 4 (S)-()-Alprenolol. Each peak, except that of the reagent, represents 25 ng of the original drug.

Courtesy of the Royal Society of Chemistry, [Ref. 15]


Figure 51 The Separation of the Diastereomers of Propanolol and Alprenolol on a Reversed Phase Column


Another group of chiral stationary phase are the macrocyclic glycopeptide phases. The macrocyclic glycopeptides were first introduced by Armstrong [16]. One way of preparing the glycopeptide phases is to covalently bond Vancomycin to the surface of silica gel particles. Vancomycin contains 18 chiral centers surrounding three 'pockets' or 'cavities' which are bridged by five aromatic rings. Strong polar groups are proximate to the ring structures to offer strong polar interactions with the solutes. This type of stationary phase is stable in mobile phases containing 0100% organic solvent. The proposed structure of Vancomycin is shown in figure 52.