Principles and Practice of Chromatography - Chromatography Applications > Liquid Chromatography Applications > Analysis of β-blockers > Page 92

The reagents reacted quantitatively with primary and secondary amino functional groups, under mild conditions (55˚C for 10 min.), in the presence of triethylamine, to produce the corresponding fluorescent thiourea derivatives. The purity of the reagents were ascertained by separation on a cyclodextrin column and the results are shown in figure 50.

The separation was carried out on a derivatized cyclodextrin column (ES-PhCD) 15 cm long and 6 mm I.D., packed with 5 mm particles. Chromatogram A shows the elution of the (R)-()-NBD-PyNCS isomer, B, the elution of the (R)-(+)-NBD-PyNCS isomer and C, the separation of the racemic mixture. The mobile phase was a mixture of acetonitrile/methanol/water : 3/3/4 v/v/v. Chromatogram D shows the elution of the (R)-()-DBD-PyNCS isomer, E, the elution of the (R)-(+)-DBD-PyNCS isomer and F, the separation of the racemic mixture. In this case, the mobile phase consisted of a mixture of acetonitrile/water : 8/2 v/v. It is seen that the cyclodextrin based stationary phase elegantly resolves both pairs of enantiomers.

 

 

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

 

Figure 50 The Separation of Enantiomeric Pairs of NBD-PyNCS and DBD-PyNCS on Utron ES-PhCD, a Cyclodextrin Based Stationary Phase