Liquid Chromatography - Liquid Chromatography Applications 8


Due to their method of manufacture, the pore volume of the micro-reticulated polystyrene gels may be significantly lower than that of silica gel. Consequently, some gels may have neither the peak capacity nor the loading capacity normally experienced with silica. However, this is generally not a problem in analytical LC. An example of the separation of some phthalate esters is shown in figure 61. The column was 30 cm long and 7.8 mm diameter. In exclusion chromatography, a large diameter column is necessary to provide adequate peak capacity (see Plate Theory and Extensions). The particle diameter of the packing was 6 mm and thus, at the optimum velocity, an efficiency of about 25000 theoretical plates should be produced. It is seen in figure 61 that the dead volume time is about 19 minutes and a flow-rate of 1.0 ml/min this would be equivalent to a dead volume of 19.5 ml.

A more typical application of micro-reticulate resins in exclusion chromatography is shown by the separation of a standard protein mixture depicted in figure 62.


Courtesy of Asahipak Inc.

Figure 62. The Separation of a Standard Protein Mixture by Exclusion Chromatography on a Vinyl Alcohol-Styrene Co-Polymer Hard Gel