ABSTRACT
Aqueous biphasic systems (ABSs) consist of two immiscible phases formed when certain water-soluble polymers [e.g., polyethylene glycol (PEG), dextran] are combined with one another or with certain inorganic salts [e.g., (NH4)2SO4, K3PO4)] in specific concentrations [1–5]. As two-phase systems, they are suitable for carrying out liquid/liquid separations of various solutes, such as biomolecules, metal ions, and particulates. In an ABS, the major component in each of the two phases is water, and because of this nondenaturing environment, these systems have been widely employed in biological separations since the first investigation of the partitioning of biomolecule particulates in 1956 using PEG/K3PO4 ABSs [6]. Surprisingly, however, a liquid/liquid extraction technology that holds the possibility of completely eliminating the use of volatile organic compounds (VOCs) has been virtually ignored for all separations except biomolecules [7,8].
