Liquid phases:

There is no fool-proof method for selecting the best liquid phase for a particular separation. The right selection is based majorly on experience and / or trial and error. Subsequent are the primary requirements of a liquid phase.

• It should be a good absolute solvent for sample solutes. If solutes are sparingly soluble within the liquid phase, they will elute rapidly and separation will be poor.
• It should exhibit differences within solubilities for different solutes in the sample.
• It should have low vapour pressure (0.01 to 0.1 mm) at operating temperatures for a reasonable column life.
• It should be thermally stable.
• It should be chemically inert toward solutes of interest at the column temperature.