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Fractionation makes it possible to isolate more than two components in a mixture in a single run. This property sets it apart from other separation techniques. Fractionation is widely employed in many branches of science and technology. Mixtures of liquids and gasses are separated by fractional distillation by difference in boiling point.
In chemistry, fractional crystallization is a stage-wise separation technique that relies on the liquid–solid phase change. This technique fractionates via differences in crystallization temperature and enables the purification of multi-component mixtures, as long as none of the constituents can act as solvents to the others.
Field-flow fractionation, abbreviated FFF, [1] is a separation technique invented by J. Calvin Giddings. The technique is based on separation of colloidal or high molecular weight substances in liquid solutions, flowing through the separation platform, which does not have a stationary phase .
AF4 and other FFF methods have been extensively used in environmental research on the impact of nano materials [2] and to characterize condensed tannins oxidation. [3] For high molar mass and branched polymers, AF4 has been shown to achieve good separation, whereas SEC fails, [4] and AF4 has been applied to polyolefines at temperatures above ...
In most cases the fractionation of polymers on a preparative scale is based on chromatographic methods (e.g. preparative SEC or Baker-Williams fractionation).Therefore, the production is normally limited to few grams only.
Fractional freezing is a process used in process engineering and chemistry to separate substances with different melting points. It can be done by partial melting of a solid, for example in zone refining of silicon or metals, or by partial crystallization of a liquid, as in freeze distillation, also called normal freezing or progressive freezing.
A fraction in chemistry is a quantity collected from a batch of a substance in a fractionating separation process. In such a process, a mixture is separated into fractions, which have compositions that vary according to a gradient. A fraction can be defined as a group of chemicals that have similar boiling points.
Measurement of natural variations in the abundances of stable isotopes of the same element is normally referred to as stable isotope analysis. This field is of interest because the differences in mass between different isotopes leads to isotope fractionation, causing measurable effects on the isotopic composition of samples, characteristic of their biological or physical history.