Chromatography is a method used to separate different components of a mixture. The principle of chromatography is based on the entrainment of a dissolved sample by a mobile phase (also called eluent) through a stationary phase (also called fixed phase). Each molecule will be more or less rapidly entrained according to its affinity for, respectively, the stationary phase and the mobile phase, allowing the separation of the different constituents present.
Analytical and Preparative Chromatography
Chromatography can be analytical (identification of the compounds present) or preparative (separation of the compounds from a mixture).
Types of Chromatography
- By mobile phase: gas (GC), liquid (LC)
- By interaction type: absorption, ion exchange, exclusion, affinity
- By support type: column, paper
Chromatography is faster with gas chromatography (GC) than with liquid chromatography (LC): a separation takes a few seconds or minutes with the former, a few minutes or hours with the latter. Moreover, the detection sensitivity is better with gas chromatography. The only limitation is that the solute must be volatile, which is not always the case for organic substances. The use of high temperatures also induces risks of denaturation of organic compounds. However, the major problem remains the choice of the mobile phase.
