Packed beds, chromatographic column

Horstmann and Chase [35] have used the mass transfer parameters determined in stirred tank experiments to simulate the breakthrough curves of affinity chromatography experiments. Numerical methods using different computer packages were carried out to solve the differential equations of the stirred tank adsorption and to predict the performances of a packed bed chromatographic column. 

Figure 9 shows the value of k as a function of the ratio of bed diameter over particle diameter, as determined from packed gas chromatographic columns (d). It can be seen that k tends to decrease as the diameter ratio increases, which implies that flow becomes more uniform. Whereas at low ratios k is inevitably high (of the same order of magnitude as in laminar flow through empty tubes) due to the wall effect, at higher diameter ratios k can vary more widely since its value depends upon whether the colunm is well or badly packed. 

For ion-exchange packed-bed chromatographic adsorption problems, a generalized adsorption rate model is proposed for multi-component systems without losing generality of conventional rate models. The new model with the exchange probability kernels can describe both active and inactive zones of the chromatographic column. The time-continuous kernels based on the LCC are developed in two respects 1) an adsorption rate becomes zero when adsorbents are not present in the liquid phase, 2) concentrations are not less than zero. The sum kernel is for the former and the product kernel for the latter situation. Consequently, this model is considered as a concentration-dependent rate model. 

The packing method supplied by the manufacturer of the gel filtration medium may need to be revised according to the column being selected. It is therefore important to have an understanding about the basic principles governing the packing of chromatographic beds. 

Each of the PLgel individual pore sizes is produced hy suspension polymerization, which yields a fairly diverse range of particle sizes. For optimum performance in a chromatographic column the particle size distribution of the beads should be narrow this is achieved by air classification after the cross-linked beads have been washed and dried thoroughly. Similarly, for consistent column performance, the particle size distribution is critical and is another quality control aspect where both the median particle size and the width of the distribution are specified. The efficiency of the packed column is extremely sensitive to the median particle size, as predicted by the van Deemter equation (4), whereas the width of the particle size distribution can affect column operating pressure and packed bed stability. 

Similar to all chromatographic processes the band of solute that emerges from the column can be broadened by a number of processes, including contributions from the apparatus, flow of the solution through the packed bed of gel particles, and the permeation process. Corrections for this zone broadening may be made empirically it generally becomes unimportant when the sample has... 

A chromatographic column was wet-packed to half capacity with a pentane slurry of Amberlyst A-29 (oa. 100-125 ml) and a glass-wool plug positioned on top of the resin bed. The remaining volume of the column was wet-packed with a pentane slurry of ferric chloride coated on Attapulgas Clay (120-125 ml). The acid-and base-free material was quantitatively transferred to... 

Several protocols can be used to fabricate packed bed structures for use in CEC. In this chapter, we will discuss the packing techniques and column fabrication protocols that have been used for packing particulate material. We concentrate, therefore, on the different approaches used to deliver chromatographic particles into the capillary column. We present an overview of the different packing protocols available to the practitioner, as well as of the CEC column fabrication method, as performed in our laboratory. Our own experiences, practices, and views regarding packing procedures are also provided, when appropriate. 

In a packed chromatographic column, the separation of a mixture of polar, ionizable biomacromolecules, such as peptides or proteins, is a consequence of two events. The first event, which controls the average retention behavior of the biosolutes, is embodied in the concept of mass distribution as the biosolutes migrate along a chromatographic bed (or column) of length L, operated at a mobile phase flow rate F. As the biosolutes move down the column, individual components interact to different extents with the chemical entities within the stationary phase and the mobile phase. When the interac-... 

Fortunately, the effects of most mobile-phase characteristics such as the nature and concentration of organic solvent or ionic additives the temperature, the pH, or the bioactivity and the relative retentiveness of a particular polypeptide or protein can be ascertained very readily from very small-scale batch test tube pilot experiments. Similarly, the influence of some sorbent variables, such as the effect of ligand composition, particle sizes, or pore diameter distribution can be ascertained from small-scale batch experiments. However, it is clear that the isothermal binding behavior of many polypeptides or proteins in static batch systems can vary significantly from what is observed in dynamic systems as usually practiced in a packed or expanded bed in column chromatographic systems. This behavior is not only related to issues of different accessibility of the polypeptides or proteins to the stationary phase surface area and hence different loading capacities, but also involves the complex relationships between diffusion kinetics and adsorption kinetics in the overall mass transport phenomenon. Thus, the more subtle effects associated with the influence of feedstock loading concentration on the... 

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