Phase diagram of a polar alcohol-salt or sugar aqueous two-phase system by cloud point method

A polar organic solvent-salt/sugar aqueous two-phase system is advantageous due to low cost, high operability, and environmental friendliness. However, there is still a lack of basic research data on the conditions and properties of two-phase formation. The aqueous two-phase formation behavior was investigated and a phase diagram was constructed by the cloud point method. The results of the cloud point method were almost in agreement with those of the component analysis method. The order of aqueous two-phase formation ability was almost consistent with the Hofmeister series, but dihydrogen phosphate ions were an exception, and it was shown that the order cannot necessarily be explained by the Hofmeister series alone. It was shown that the more hydrophobic the polar alcohol is, the more likely it is to form aqueous two-phases. Furthermore, the sugar system was less likely to form two aqueous phases than the salt system, and in mixed systems of salt and sugar, aqueous two-phase formation becomes more difficult as the mole fraction of sugar increases.