Scaling column

Under constant pattern conditions the LUB is independent of column length although, of course, it depends on other process variables. The procedure is therefore to determine the LUB in a small laboratory or pilot-scale column packed with the same adsorbent and operated under the same flow conditions. The length of column needed can then be found simply by adding the LUB to the length calculated from equiUbrium considerations, assuming a shock concentration front. 

One potential problem with this approach is that heat loss from a small scale column is much greater than from a larger diameter column. As a result, small columns tend to operate almost isotherm ally whereas in a large column the system is almost adiabatic. Since the temperature profile in general affects the concentration profile, the LUB may be underestimated unless great care is taken to ensure adiabatic operation of the experimental column. 

Four column systems are available from Amersham Pharmacia Biotech that can be used to pack SEC media for various applications at the laboratory scale. These include C, XK, SR, and HR column systems. All of the laboratory-scale columns are constructed with borosilicate glass tubes. Columns for larger scale process applications include INdEX, BPG, EineLINE, BPSS, and Stack columns. The larger scale columns are constructed to meet stringent validation requirements for the production of biopharmaceuticals. Each of the column types are described. 

As a practical result, the amount of gel to be prepared for a preparative column must exceed the nominal volume of the final column by 10%. For the packing of production-scale columns the maximum pressure rate of the column has to be considered. The large columns consist mostly of borosilicate glass tubes with similar pressure stabilities. For example, a Superformance column with dimensions of 1000 mm in length and 50 mm in width is pressure stable up to 14 bar. Therefore, Fractogel EMD BioSEC should be packed with a... 

In order to determine rigorously the process parameters, a few relevant parameters are to be experimentally determined on a laboratory scale column. 

Process scale columns generally are constructed essentially the same as analytical columns. With larger column diameters, however, this type of construction... 

Chromatographic use of monolithic silica columns has been attracting considerable attention because they can potentially provide higher overall performance than particle-packed columns based on the variable external porosity and through-pore size/skeleton size ratios. These subjects have been recently reviewed with particular interests in fundamental properties, applications, or chemical modifications (Tanaka et al., 2001 Siouffi, 2003 Cabrera, 2004 Eeltink et al., 2004 Rieux et al., 2005). Commercially available monolithic silica columns at this time include conventional size columns (4.6 mm i.d., 1-10 cm), capillary columns (50-200 pm i.d., 15-30 cm), and preparative scale columns (25 mm i.d., 10 cm). 

Figure 12.7 Purification of factor VIII complex using immunoaffinity chromatography. The immobilized anti-factor VIII antibody is of mouse origin. Antibodies raised against specific epitopes on both the VIII C and vWF components have both been successfully used. Industrial-scale columns would often exhibit a bed volume of several litres. Note that the different elements in this diagram are not drawn to the correct scale relative to each other...

Laboratory scale columns tend to make important demands for new material and this fact, coupled with relatively long timescales needed for these studies, contributes to limit the number of small-scale experiments that can be successfully carried out [49, 50], resulting in full-scale processes which are however sub-optimal from both technical and economic perspectives. 

We will neglect any delay time (deadtime) in the vapor line from the top of the column to the reflux drum and in the reflux line back to the top tray (in industrial-scale columns this is usually a good assumption, but not in small-scale laboratory columns). Notice that y T is not equal, dynamically, to x. The two... 

Isolation of Carbohydrates on Analytical-Scale Columns, and Instmmentation Used... 

Isolation of Carbohydrates on Large-Scale Columns, and Instrumentation... 

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