Radial flow chromatography

Alternative Chromatographic Columns Commercial radial-flow chromatography (RFC) columns first appeared in the mid-1980s. RFC is an alternative to the conventional axial-flow chromatography for preparative- and large-scale applications. In a RFC column, the mobile phase flows in the radial direction rather than the axial direction. Computer simulation proves that RFC is somewhat equivalent to a pancakelike axial-flow column [Gu, in Flickinger and Drew (eds.). 

Saxena, V., Subramanian, K., Saxena, S., and Dunn, M., Production-scale radial flow chromatography, Biopharmacology, 36, 46, 1989. 

Weaver, K., Chen, D., Walton, L., Elwell, L., and Ray, R, Uridine phosphorylase purified from total crude extracts of E. coli using Q Sepharose and radial-flow chromatography, Biopharmacology, 37, 25, 1990. 

If a pancake column is rolled into a tube, the result is radial-flow chromatography. This geometry has already been commercialized for... 

Saxena, V. Dunn, M "Solving Scaleup Radial-flow Chromatography" Bio/Technology. 1989, 7, pp 250-255. 

Another alternative chromatographic procedure for preparative separations is radialflow chromatography. The radial flow chromatography columns consist of two concentric porous cylindrical... 

The Simulated Moving Bed Preparative Chromatography System Radial Flow Chromatography... 

In radial flow chromatography, the adsorbent is packed between two concentric cylindrical porous frits. Eluent and feed flow via capillary channels from the top of the instmment to the outer cylinders through the stationary phase to the inner porous cylinder and then to the exit port of the column, see Fig. 12. The separation path length is therefore comparatively short, i.e., equal to the thickness of the annulus. Radial chromatography has been developed to overcome backpressure problems that can arise when a process is scaled up from the laboratory to the production scale. A unit is easily scalable because the length of the cylinder may be increased while the sample path/backpressure stays constant. Column backpressures... 

McCartney, J. E., Rapid purification of a recombinant protein using tandem radial flow ion-exchange column chromatography, BioTechniques, 11,648,1991. 

Figure 27.7 Radial-flow thin-layer electrochemical cell for microbore chromatography.

FIGURE 8 Arrangement of multiple radial flow modules to increase capacity and flow rate. Two 8 m2 modules were connected in parallel, with one 4 m2 module in series, in conjunction with a final I m2 module in series. Total membrane area is 21 m2. (Adapted from Journal of Chromatography, Vol. 852, W. Demmer and D. Nussbaumer, Large-scale membrane adsorbers, 73-81. Copyright 1999 with... 

Planques, Y., Pora, H., and Menozzi, F. D. (1991). Affinity purification of plasminogen by radial-flow affinity chromatography. ]. Chromatogr. 539, 531-533. 

Radial compression uses radial pressure applied to a flexible-wall column to lessen wall effects. The mobile phase has a tendency to flow slightly faster near the wall of the column because of decreased permeability. The solute molecules that happen to be near the wall are carried along faster than the average of the solute band, and, consequently, band spreading results. Preparative scale radial compression chromatography columns have been found to possess efficiencies close to those of analytical-scale columns when an adequate radial compression level is used. Radial compression technology also helps lower the cost by substituting reusable column holders in place of expensive steel columns. 

The use of annular cylindrical beds, fed through a central channel and drained at the periphery, is of potential interest in cases where high throughput rates and wide but shallow beds are desired. Radial-flow geometry is also characteristic of one operating method used in paper chromatography. 

The most common column system used in preparative chromatography is the axial flow cylindrical column and consequently this type of column will be considered first and in some detail. Radial flow columns, and simulated moving bed columns are also used very effectively in preparative chromatography, but these systems constitute very special and expensive apparatus. In addition, initial work with traditional columns will need to be carried out to evaluate and justify the necessary expense that is involved with these more sophisticated type of preparatiye separation systems. 

The Separation of Some Large Biomolecules Using Radial -Flow Reverse Phase Chromatography... 

An alternative approach was suggested by Podgomik et al. They implemented radial flow mode and introduced monolithic columns of a well defined thickness. A similar idea was later implemented for the preparation of agarose monolithic columns, which were applied to pseudoaffinity chromatography using Cibacron Blue 3GA as a ligand and as bioreactors with the immobilized enzyme (3-galactosidase. 

A solution of this nondispersive packed-bed adsorption with radial flow is available (Lapidus and Amundson, 1950) under the condition of elution chromatography (we... 

If the position of sample application and the point of entry of the mobile phase are at the center of the plate and the flow of mobile phase is towards the periphery of the plate, then this node of development is called circular chromatography [6,110]. Samples can be injected into the mobile phase, in which case they will be separated as a series of concentric rings. If the samples are applied as a cluster of spots in a radial pattern around the solvent entry position, after development, spots near the origin remain symmetrical and compact trtiile those near the solvent front are compressed in the direction of development and elongated at right angles to this direction. Figure 7.10(A). 

New designs for axial flow process chromatography columns have been examined using ovalbumin separation on Whatman Express-Ion Exchanger Q with a 16 L Side-Pack and a 24 L IsoPak column.38 The Side-Pak column is packed in the transverse direction, so radial inhomogeneity is minimized. 

Turner and Warnock [56] determined miconazole in human saliva using high performance liquid chromatography. Deproteinated human saliva samples containing miconazole was chromatographed on a C8 reversed-phase radial compression column using 77% methanol in 0.01 M EDTA with 0.005 M w-nonylamine at a flow... 

Thus in turbulent flow, the dispersion coefficient is independent of the diffusion coefficient, but in laminar flow, the dispersion coefficient depends inversely on the diffusion coefficient. This counterintuitive inverse dependence, the result of axial convection coupled with radial diffusion, is the foundation of the Goulay equation describing peak spreading in chromatography. We now return from this dispersion tangent back to diffusion and in particular, to mass transfer. 

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