Aqueous Two-Phase Systems (ATPS) are known since 1896, when Beijerinck reported
the formation of a biphasic system after mixing aqueous solutions of gelatine and agar
or gelatine and starch. However, only in the 50’s, Albertsson showed the potential of
these systems in the separation and purification of several biological constituents.1 In
general, ATPS are obtained by mixing two aqueous solutions of different constituents
that become immiscible above certain critical conditions, like temperature,
concentration, etc. Both phases are composed mainly by water (>80%) and each one is
enriched in a different component. ATPS formed by two polymers or a polymer and a
salt represent the traditional systems. Nevertheless, other alternative biphasic systems
can be obtained using surfactants, micellar compounds or ionic liquids
