The research on nonaqueous two-phase systems, i.e., ternary nonaqueous systems with a liquid–liquid phase split induced by a solid component, is discussed. Previous scattered reports are reviewed and summarized. The first systematic studies are described in detail. These included qualitative testing of numerous ternary systems (a solid component and two liquid solvents, significantly different in polarity) to determine whether a liquid–liquid phase split occurred. Some correlations between this occurrence and the Hofmeister series were suggested. The liquid–liquid equilibrium was determined experimentally in a few systems, and the problems encountered during this determination are discussed. Possible applications and further topics of investigation are suggested.
Hofman et al. (2026) studied this question.