Recovery of Mass and Biological Activity

The primary concerns of the process chromatographer are final product purity and process economy. This can be interpreted as selectivity and productivity as defined by capacity and speed. The choice of the chromatographic media has a dramatic effect on the overall performance of the process separation and is therefore critical if these objectives are to be achieved. There are now available many different types of polymeric packings (Table 5-3) which enable options to be considered but which only a few years ago where not available. 

Toyo Soda Hydrophilic vinyl polymer TSKgel PW 

For separations based on molecular size in solution, ie, size exclusion chromatography, the semi-rigid hydrophilic gels, dextran, agarose or cellulose based, are normally the materials of choice. In order to improve mechanical stability some cross-linking has been carried out which has increased the throughput of the fractionation process. The highly cross-linked synthetic polymers are not yet widely used on a process scale. 

In interactive chromatography, such as ion exchange, the productivity of the separation depends upon a number of related variables. The binding capacity of the media and the maximum operational flow rate are the most important. With the natural polymers, such as dextran, agarose and cellulose, which have high available surface areas and hence capacities, the compressibilities of the gels limits the operational flow rates which can be used so restricting the amount of product which can 

When developing a process, initial studies will be carried out at laboratory-scale. Here, the selection of chromatographic techniques will be made such that a series of steps starting from crude feedstock and resulting in purified product will be iden- 

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SEC offers several advantages that make it a desirable technique for both preparative and analytical applications. First, separations are rapid with an 8 x 300 mm analytical column operated at 1 ml/min, all analytes elute in about 10 min. Second, because the stationary phase is designed to eliminate interactions with the sample, SEC columns exhibit excellent recovery of mass and biological activity. Third, because all separations are performed under isocratic conditions, peak area and retention time precision are high. 

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