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Abstract
Although some aqueous three-phase systems have been tested, they have never been combined with a countercurrent distribution (CCD) technique in order to create a new separation method.
Partitioning of bovine serum albumin (BSA) in an aqueous double countercurrent distribution (DCCD) using a three-phase system was studied and compared with the countercurrent distribution using a two-phase system. The two-phase system was composed of Dextran and Polyethylene glycol (PEG) solutions, and the three-phase system consisted of Dextran, Ficoll, and PEG solutions. These solutions have low polymer concentration (about 10% w/w), and are normally gentle to extractants and safe for our environment.
In the double countercurrent distribution experiment, BSA was partitioned from the stationary bottom phase into the moving middle and top phases. Two peaks were formed on the distribution curve. The relationship between the tube numbers and the peaks, and the relationship between the two peaks are characteristics of the partitioned substance BSA. These characteristics not only provide quantitative analysis of the distribution, they also help in qualitative analysis of the partitioned substance.
This DCCD method has shown advantages over the traditional CCD method. More BSA was extracted from the bottom phase, and the selectivity as well as the purity can be higher also.
