Membrane chromatography capacity

In addition, it has been shown that membrane adsorbers are competitive in bind-and-elute applications for large solutes such as DNA, RNA, and viruses. Most bead chromatographic media have pore sizes that are too small, which exclude large molecules from entering and binding to specific sites. Under these circumstances, membrane chromatography exhibits a competitive binding capacity for these molecules, such as DNA. 

MA systems can easily add a module to increase membrane capacity or resolution. Alternatively, the series addition of a traditional chromatography column for improvement of capacity or resolution is seldom practiced. Thus, membrane chromatography offers the chromatographer a new flexibility of easy expansion of inadequate systems. Alternatively, the easy connectibility also enables a simple way to couple multiple units of different chemistries for a mixed-mode separation.43 The next section describes these configurations in greater details. 

Membrane chromatography proved to be a successful tool especially for separation of macromolecules. The large-size proteins cannot enter the small pores of the particles in the packed-bed columns, while in membrane-based processes they have access to a much higher binding surface due to the macroporous nature of the supports. One problem may nevertheless appear for membranes with large pore distribution. Suen [182] reported that a variation of 12% in porosity can be responsible for a loss of 50% of adsorption capacity at the breakthrough point. For variations in the membrane thickness a three times less-sensitive behavior was found. 

Adoption of membrane chromatography will require increases in binding capacity without an increase in cost. Moreover, if costs can be reduced sufficiently, single use columns could eliminate the need for some current chromatography steps [82]. Like chromatography, improvement in virus filters, especially for use in industry preferred normal flow filtration, will require increases in capacity/throughput and reduction in costs. 

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