Ternary Aqueous solutions of poly(vinylpyrrolidone) (PVP) and certain electerolytes seperate into a PVP-rich and a salt-rich phase over part of the composition space. Aqueous two-phase systems of this nature are useful for the separation and purification of biomaterials where the employment of a nonpolar solvent/aqueous phase system whould lead to degredation of biological activity [1 , 2].
