Stevenson R.L.,American Laboratory Laboratory Compare
American Laboratory | Year: 2013
A stable expanded bed is achieved when the adsorbent particles are levitated by balancing gravity with the frictional force of the upwelling liquid according to Stokes law. In first-generation EBA, even at a low flow rate some of the adsorbent found its way into the waste vessel. Over the intervening years, the advent of specialized high-density column packings coupled with improved column design has opened the operating window wide. The heavier particles were synthesized by encasing a dense tungsten carbide core with cross-linked agarose. The selectivity of the adsorbent particles depends on the ligands bonded to the agarose. Sulfonyl propyl groups selectively adsorb cations by cation exchange. Protein A uses bioaffinity chromatography to capture antibodies. A mixed-mode phase combines hydrophobic and cation exchange selection. The agarose layer is open on the exterior surface, which improves binding capacity.