General Characteristics of Membrane Chromatography

In contrast to chromatographic supports based on beaded resins with dead end pores, membrane chromatographic supports have through-pores and lack interstitial space. Mass transfer is mainly governed by forced convection and pore diffusion is negligible. The observed back-pressures are normally quite low, and high flow rates and thus high throughputs and fast separations become possible without the need for high pressure pumps or equipment. As the association time for an antibody-antigen complex is typically about 1 s or less, but the diffusion of a protein molecule to the centre of a 50 |im porous bead takes tens of seconds, in a membrane support, the low diffusional limitation leads to faster adsorption kinetics and higher throughput efficiency. Little deterioration of the separation efficiency occurs even at elevated flow rates. On the other hand, with affinity membranes the formation of the affinity complex can become the rate-limiting process at high flow rates.

A problem often encountered in membrane chromatography is extra-cartridge back-mixing, which can severely degrade membrane performance. This phenomenon is due to dead volumes outside the membrane, in tubing, fittings and valves, and leads to peak broadening and dilution. It is more pronounced in membrane chromatography systems compared to conventional columns packed with beaded supports, owing to the larger throughput/bed volume ratio.

Although the specific surface area of membranes is typically only 1% of that of conventional chromato-graphic resins, microporous membrane systems have high internal surface areas and reasonably high capacities. The open-pore structure of membranes increases the accessibility of affinity ligands and reduces steric hindrance compared to small-pore adsorbents.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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