https://doi.org/10.1351/goldbook.10195
Separation of close-boiling liquids by fractional distillation in the presence of a low-volatility solvent or salt that selectively interacts with one or more components of the mixture, increasing the difference in vapour pressure of the sample components.
Note: If the separation solvent forms an azeotrope with one or more sample components the process is called azeotropic distillation.