Continuous Affinity Chromotography

One specific type of operation that would lend itself to a totally new approach to continuous operation is Affinity Chromatography. Affinity Chromatography, in which sites on the packing, or beads, have specific binding properties with the material of interest, provides a powerful means to selectively purify a material. The affinity of this material to these sites is usually dependent on the properties of the material passing through the column, with binding occurring at one salt type or concentration and un-binding, or releasing occurring at another. This specific two-step process is unique enough to form the basis for a continuous chromatography system that could totally eliminate the need for packed columns.

Figure 1 shows such a system. To the Broth containing the Product, solvent, and impurities, affinity beads with specific binding properties are added. These beads are contacted with the Broth either by mechanical agitation in a container or by recirculation in a loop to facilitate good contact between the broth and the bead surface. The Product is now "bound" to the surface of these beads, a solid. Now comes the key to this operation, the broth and bead mixture is pumped to the Disposable Rotary Drum Filter that physically separates the solid beads carrying the Product and the liquid Broth including the impurities. These Product-carrying beads are now re-suspended in a solution that releases the Product from the beads. Again contact between the releasing solution and the beads must be provided in a like manner as it was originally done in the initial Broth. This Releasing Solution / Bead mixture is now sent to another Disposable Rotary Drum Filter that separates the two leaving the Product in the liquid and the washed beads as the solid. The product is now taken on to further processing and the beads can go to waste or reuse.

If contaminants are initial bound to the beads, filtrate from the first solid / liquid separation becomes the product. The second solid / liquid separation is only needed if the beads are to be recovered.

The beauty of this system is that it can be either conducted in a batch mode, that is already a great advantage over traditional chromatography columns, or in a fully continuous mode. This later mode is easily produced by feeding Affinity Beads, Broth, and Releasing Solution continuously into their respective containers. As a result, this method could continuously produce product until the feed to the Broth container is exhausted. This would usually consist of a "lot" of material.

Steadfast Equipment supplies two basic components for the Disposable Rotary Drum Filter, the Filter itself which is a single use disposable unit, and the Drive and Holder assembly, which is reusable.