“…The acquisition of liquid–liquid equilibrium data for new green ATPS with greater hydrophobicity, investigating the effect of the hydrophobic/hydrophilic balance of the macromolecule on the formation of the systems, can assist in elucidating the mechanisms that lead to their formation to expand the potential applications in the field of separation/purification. Different electrolytes have been used in the literature to obtain ATPS composed of macromolecules, such as sulfates, − phosphates, , citrates, , thiocyanates, and tartrates. ,,, However, as far as we know, liquid–liquid equilibrium data made up of ammonium thiosulfate are not related in the literature. Two studies reporting the use of sodium thiosulfate to obtain ATPS with PEO with a molar mass of 1500, 4000, or 6000 g mol –1 . , The use of ammonium thiosulfate ((NH 4 ) 2 S 2 O 3 ) as the electrolyte is an excellent strategy for the separation of analytes, mainly metal ions, because, compared to many other salts, it is inexpensive and nontoxic and has reducing and complexing characteristics.…”