Lab & analytical techniques · Reference
What is chromatography?
Chromatography separates the components of a mixture by their differing affinities for a stationary phase versus a moving mobile phase. Components travel at different speeds and emerge separately.
The separation principle
Every chromatographic method relies on the same idea. A mobile phase — a liquid or a gas — carries the sample over or through a stationary phase, which may be a solid surface or a liquid film fixed in a column or on a plate. Each component distributes itself between the two phases according to its chemistry; substances that prefer the stationary phase are held back, while those that prefer the mobile phase move quickly. This differential partition spreads the components out, so they reach the end of the system at different times and can be collected or detected separately.
History
Chromatography was developed by the Russian-Italian botanist Mikhail Tswett (Tsvet) in the early 1900s. He separated plant pigments by passing a solvent through a column packed with powdered chalk, producing coloured bands — the observation that gave the method its name, from the Greek for "colour writing". The principle was later generalised far beyond coloured substances, becoming a cornerstone of analytical chemistry.
Types of chromatography
Chromatographic methods are classified by the physical form and by the nature of the phases. Paper and thin-layer chromatography use a flat stationary phase; column methods pack the stationary phase into a tube.
The most powerful instrumental forms are gas chromatography, where the mobile phase is an inert gas, and high-performance liquid chromatography, where a liquid is forced through under high pressure. Detectors at the column outlet — often coupled to mass spectrometry — identify and quantify the separated components.
Key facts
At a glance
- Separates: mixture components by differential partition
- Two phases: a stationary phase and a mobile phase
- Named by: Mikhail Tswett, early 1900s (plant pigments)
- Name meaning: "colour writing" (Greek)
- Major instrumental forms: GC and HPLC
- Output: separated components for identification and measurement
Common questions
FAQ
How does chromatography separate a mixture?+
A mobile phase carries the mixture over a stationary phase, and each component partitions between the two phases differently. Components that bind the stationary phase more strongly move slowly, so the substances travel at different speeds and separate.
Who invented chromatography?+
Chromatography was developed by the botanist Mikhail Tswett in the early twentieth century, who used it to separate the coloured pigments of plants on a column of powdered chalk. The technique was later generalised to colourless substances.
Going deeper
Related on CASRAI
- What is HPLC? →
- What is gas chromatography? →
- What is mass spectrometry? →
- Laboratory & analytical techniques →
- Research methods →
Sources
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