Ethanol fractionation of plasma proteins

The problems involved in the use of crystallization to fractionate a number of similar solutes in solution can be illustrated by the current approaches to the fractionation of plasma proteins. Chapter 12 in this book discusses the fundamentals of crystallization of proteins. Here our purpose is to demonstrate how the manipulation of relevant process variables can effect the fractionation of mixtures of pharmaceutical-like compounds. 

In the late 1940s, a method was developed (Cohn et al. 1946) for the fractionation of proteins from blood plasma by means of ethanol (an anti-solvent) addition to aqueous solutions at specified conditions of temperature, pH, and ionic strength. Briefly, a series of five successive batch ethanol precipitations were used to prepare fractions of fibrinogens, globulins, and albumin. The conditions used in each step are in Table 11.1 along with the major protein(s) precipitated at each step. More recently, a method employing a series of MSMPR precipitators has been reported (Chang 1988). 

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TABLE 11.1 Conditions for Ethanol Fractionation of Plasma Proteins... 

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