Aqueous biphasic systems (ABS) are usually formed by mixing a kosmotropic solute and a chaotropic solute in an aqueous solution above a certain critical concentration. Both of kosmotropic and chaotropic solutes can be a polymer, salt, ionic liquid and amino acid to form the polymerpolymer, salt-polymer, IL-polymer, salt-IL, aminoacid-polymer, IL-amino acid, … ABS. ABS consist of two immiscible aqueous-rich phases in which each phase contains mainly one of the compounds and a small amount of the other, with water as solvent in both phases with mass fraction (80 to 90) % in the equilibrium phases. The aqueous nature of both phases as well as difference in their properties makes it possible to use them for the partitioning and separation of biological materials both in industry and academia [1]. Although determination of phase equilibrium data of these ABS and their application to purification of a variety of biomolecules has been studied extensively, but experimental efforts aiming at the understanding of the underlying reasons for the formation of aqueous biphasic systems are considerably fewer and there remains considerable uncertainty as to the details of the mechanism of this phase separation. In an attempt to obtain further evidence about the salting effect produced in different aqueous solutions, in the present paper we apply our proposed mechanism for salt effects in aqueous salt-IL [2], salt-polymer [3] and IL-polymer [4] systems to all types of ABS mentioned above and in order to cover a range of kosmotropic and chaotropic behaviors, an extensive series of ternary aqueous systems containing different solutes capable or not of inducing phase separation were investigated.
