<unk>  is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. It is a special type of<unk> . Generally the component parts boil at less than 25°C from each other under a pressure of one atmosphere (atm). If the difference in boiling points is greater than 25°C, a simple<unk>  is used.
Fractional distillation
Solid phase extraction
Liquid-liquid extraction
Gas diffusion method
Ion chromatography
Kick chart
Freeze drying
International Union of Pure and Applied Chemistry nomenclature