BUFFER EXCHANGE-USING SIZE-EXCLUSION CHROMATOGRAPHY, COUNTERCURRENT DIALYSIS, AND TANGENTIAL FLOW FILTRATION - MODELS, DEVELOPMENT, AND INDUSTRIAL APPLICATION

There are three major methods for buffer exchange of proteins at indus trial scale: size exclusion chromatography (SEC), tangential flow filt ration (TFF), and countercurrent dialysis (CCD). In order to determine the optimal technology for a given process, a study was done to compa re these technologies on a technological and economic basis. This comp arison required that new mathematical models be developed which enable the common features of each unit operation to be directly compared. T he new concept of a diavolume equivalent for SEC, defined as the inver se of the fractional loading, was also introduced to aid in this compa rison. Variables that were examined for each unit operation included r ange of buffer exchange, dilution of protein solution, yield, buffer r equirements, total operating time, throughput, plant space, capital, r aw materials, and labor costs. It was found that TFF and CCD have a gr eater range of buffer exchange than SEC. TFF also provides the advanta ge that concentration of the protein can readily be accomplished in th e same step. For processes of equal batch size and yield, TFF and CCD also provide a two- to fivefold improvement in each of the remaining v ariables. The major economic advantage in using TFF and CCD over SEC i s the decreased plant size required for manufacturing and thus the lon ger term use of existing facilities. Situations where SEC (or CCD) wou ld be favored over TFF are when protein denaturation occurs in TFF but does not occur in SEC. (C) 1995 John Wiley & Sons, Inc.