Liquid Chromatography - Liquid Chromatography Applications 7


The column packing was a strong anion exchange resin designated as TSKgel Sugar AXG. It had a particle diameter of 10 m and contained quaternary ammonium ions as the ion exchange moiety. The column was 15 cm long, 4.6 mm in diameter and had a potential efficiency of about 7,500 theoretical plates. The mobile phase consisted of three borate buffer solutions which were used in a stepwise gradient. The first buffer solution was a 0.5 M borate buffer (pH 7.7), the second a 0.7 M borate buffer (pH 7.3) and the last a 0.7 M borate buffer (pH 8.7) and the flow rate was 4 ml/min .

The last example clearly broaches an decidedly different approach to the sample separation. It is just as feasible for the solutes to be modified to suit a particular phase system as it is to choose or modify a phase system to suit the solutes. This emphasizes the wide range of variables and alternative approaches that liquid chromatography provides for the analyst.

Before ending an example needs to be include that utilizes Micro-reticulated polystyrene gels as a stationary phase. Micro-reticulated polystyrene gels, as already discussed, are formed from cross-linked styrene-divinyl benzene polymers and can be manufactured with a wide range of different pore sizes. Micro-reticulated polystyrene gels, however, are not used solely for the separation of large multi-interactive molecules (e.g., protein and polypeptide mixtures), but can be used for the same type of analyses as silica gel.

Courtesy of Supelco Inc.

Figure 61. Separation of Some Phthalate Esters by Exclusion Chromatography on Styrene-Divinyl Benzene Based Gel