Effect of sodium chloride on solute-solvent interactions in aqueous polyethylene glycol-sodium sulfate two-phase systems.

•Solvent properties of PEG-8000-Na2SO4 ATPS containing 0.215M NaCl and 0.5M osmolyte (sorbitol, sucrose, TMAO) and PEG-10000–Na2SO4–0.215M NaCl are characterized.•Partitioning of eight organic compounds and six proteins in the systems are examined.•Partition behavior of all solutes is considered in terms of solute-solvent interactions.•It is established that NaCl additive interacts with the solutes in the presence of exceeding amount of Na2SO4.