Three Phase Purification Strategy

With background information, assays and sample preparation procedures in place the Three Phase Purification Strategy can be considered. 

Imagine the purification has three phases Capture, Intermediate Purification and Polishing. 

In the Three Phase Strategy specific objectives are assigned to each step within the process  

In the capture phase the objectives are to isolate, concentrate and stabilise the target product. 

During the intermediate purification phase the objective is to remove most of the bulk impurities such as other proteins and nucleic acids, endotoxins and viruses. 

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With background information, assays, and sample preparation and extraction procedures in place the Three Phase Purification Strategy can be applied (Figure 3). This strategy is used as an aid to the development of purification processes for therapeutic proteins in the pharmaceutical industry and is equally efficient as an aid when developing purification schemes in the research laboratory. 

A guide to the suitability of each purification technique for the stages in the Three Phase Purification Strategy is shown in Table 4. 

Table 4. Suitability of purification techniques for the Three Phase Purification Strategy...

In the Three Phase Strategy a specific objective is assigned to each step. The purification problem associated with a particular step will depend greatly upon the properties of the starting material. Thus, the objective of a purification step will vary according to its position in the process i.e. at the beginning for isolation of product from crude sample, in the middle for further purification of partially purified sample, or at the end for final clean up of an almost pure product. 

A basic difficulty that we find with the LHASA - SECS - REACT strategies is that the reaction paths are more typical of a discrete step-wise laboratory procedure. The use of named organic chemical transforms leads to a bench scale procedure. Reactions of industrial interest on the other hand are generally carried on in one to three continuous steps, with a minimal use of reagents and purification steps. Solid catalyzed vapor or liquid phase reactions are favored. Intermediates and raw materials are far more limited in variety on the scale of industrial production. 

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