This operation simulates a PBA column loading step in bind-and-elute chromatography where (typically but not necessarily) the target protein binds to the column and impurities flow through. The main objectives of this operation are to estimate the time for loading a column, account for bound mass in the column and, if in Design Mode, estimate the number and size of columns required.
● Packed Bed Adsorption (PBA) Chromatography Procedure (Detailed) in Bind-and-Elute Mode
In this operation you need to specify the resin’s binding capacity. This refers to the maximum mass of all components (except those ‘ignored in sizing’ as explained below) that can bind to the resin, divided by the resin (bed) volume. Its value can be either measured experimentally or approximated using Scopes' correlation, provided that the molecular weight of the main components is known (Scopes, 1982; p.105, Fig. 5.3).
You also need to specify the retained mass % for each component. This is the percentage of the mass of that component in the feed stream that is retained in the resin. By default, all retained mass is considered bound to the resin. If a component’s retained mass is not bound, or if that component is not considered when the binding capacity is determined, you can instruct the program to ignore that component in sizing calculations by checking the ‘Ignore in Sizing ?’ box next to it.
The required bed volume per cycle, V, can be calculated as:
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Where:
● Q is the volume of material processed by the bed per plant batch time.
● n is the number of cycles per batch.
● k is the total number of components in the feed stream.
● Ci is the concentration of component ‘i’ in the feed stream.
● Fi is the retained % that is assigned to component ‘i’ for equipment sizing purposes; if the ‘Ignore in Sizing ?’ option is checked, Fi is set to 0.0; if the ‘Ignore in Sizing ?’ option is not checked, Fi is set equal to the specified retained %.
● C is the resin binding capacity per volume.
● ODF is the overdesign factor.
When the bed height (L) and the maximum bed (or column) diameter (Dmax) are specified, the bed (or column) diameter is calculated by the following equation:
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If D > Dmax, then multiple columns are assumed in parallel. Similarly, the user may decide to fix the diameter and have the program calculate the height.
The process time can be either set by user or calculated based on loading flowrate and feed volume as follows:
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If the process time is set by user then the above equation is used to calculate the absolute loading flowrate.
If the loading time is calculated based on loading flowrate, you can choose among four different options for specifying the loading flowrate: you can specify the feed’s linear velocity, or its volumetric flowrate, or its relative flowrate (in bed volumes) in the bed, or the empty bed contact time (the amount of time it takes for a feed volume of material to flow through an empty bed). Any variable that is not specified will be calculated by the program based on the following relations:
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If the loading time is set by the user, then the program will first calculate the absolute flowrate from eq. (A.166) and then it will calculate the linear velocity, relative flowrate, and empty bed contact time from eq. (A.163), eq. (A.164), and eq. (A.165), respectively.
For each component, a percentage of the corresponding amount in the feed stream equal to the specified retained mass % for that component is retained in the bed. Everything else ends up in the specified outlet (wate) stream.
The cost associated with resin replacement is estimated as for all consumables (see Consumables Cost). For resins that last several years, the user may decide to depreciate the first resin fill-in by checking the ‘Is First Resin capitalized’ check box in the equipment consumables tab.
1. R.K. Scopes (1987). Protein Purification, Springer-Verlag.
2. H. Johansson, M. Ostling, G. Sofer, H. Wahlstrom, and D. Low (1988). Chromatographic Equipment for Large-Scale Protein and Peptide Purification. in “Advances in Biotechnological Processes”, Vol. 8, Edited by: A. Mizrahi, Published by Alan R. Liss, Inc.
3. R.W. Yost, L.S. Ettre, and R.D. Conlon (1980). Practical Liquid Chromatography - An Introduction. The Perkin-Elmer Corporation.
The interface of this operation has the following tabs:
● Oper. Cond’s, see PBA Column Loading: Oper. Conds Tab
● Labor, etc, see Operations Dialog: Labor etc. Tab
● Description, see Operations Dialog: Description Tab
● Batch Sheet, see Operations Dialog: Batch Sheet Tab
● Scheduling, see Operations Dialog: Scheduling Tab
