Chromotography

Chromatography
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Pictured is a sophisticated gas chromatography system. This instrument records concentrations of acrylonitrile in the air at various points throughout the chemical laboratory.
Chromatography (from Greek χρῶμα chroma "color" and γράφειν graphein "to write") is the collective term for a set of laboratory techniques for the separation of mixtures. It involves passing a mixture dissolved in a "mobile phase" through a stationary phase, which separates the analyte to be measured from other molecules in the mixture based on differential partitioning between the mobile and stationary phases. Subtle differences in a compound's partition coefficient result in differential retention on the stationary phase and thus changing the separation.
Chromatography may be preparative or analytical. The purpose of preparative chromatography is to separate the components of a mixture for further use (and is thus a form of purification). Analytical chromatography is done normally with smaller amounts of material and is for measuring the relative proportions of analytes in a mixture. The two are not mutually exclusive.
Contents[hide]   * 1 History   * 2 Chromatography terms   * 3 Techniques by chromatographic bed shape       * 3.1 Column chromatography       * 3.2 Planar chromatography           * 3.2.1 Paper chromatography         * 3.2.2 Thin layer chromatography   * 4 Displacement chromatography   * 5 Techniques by physical state of mobile phase       * 5.1 Gas chromatography       * 5.2 Liquid chromatography   * 6 Affinity chromatography       * 6.1 Supercritical fluid chromatography   * 7 Techniques by separation mechanism       * 7.1 Ion exchange chromatography       * 7.2 Size-exclusion chromatography   * 8 Special techniques       * 8.1 Reversed-phase chromatography       * 8.2 Two-dimensional chromatography       * 8.3 Simulated moving-bed chromatography       * 8.4 Pyrolysis gas chromatography...