Chromatography

The term chromatography is derived from two Greek words; the first, chroma translates into “color,” and the second one, graphein, is the verb “to write.” Chromatography is the collective term for a set of laboratory procedures used in the separation of mixtures. The mixture is typically dissolved in a fluid, in a step known as the mobile phase. The mobile phase carries the mixture through a structure that holds another material, which is called the stationary phase.

The various components of the mixture travel through the phases at different speeds, and this difference in speed causes the components to separate. This separation is based on differential partitioning between the mobile phase and the stationary phase. Differential retention on the stationary phase—and therefore, the change in the separation—can stem from the subtle differences in a specific compound’s partition coefficient.

There are two main kinds of chromatography: preparative chromatography and analytical chromatography. Preparative chromatography is used to separate the components of a certain mixture for a more advanced use, and many scientists, researchers, and technicians use this technique in order to purify a mixture. On the other hand, analytical chromatography is done with relatively smaller amounts of the material, and is used for measuring the relative proportions of analytes in a specific mixture.

Chromatography has been used since the 1900’s, when it was first employed by a Russian scientist named Mikhail Tsvet. He used chromatography to separate plant pigments such as carotenes, chlorophyll, and xanthophylls. These plant pigments have different colors and therefore gave the technique its present name. During the 1930’s and the 1940’s, new types of chromatography have been developed and made the technique useful for many other separation processes.

This section contains scientific information on chromatography, the collective term for a set of laboratory procedures used in the separation of mixtures.