Types of chromatography
1. Liquid chromatography (LC): In this technique, the sample mixture is dissolved in a liquid solvent and passed through a column filled with a stationary phase. The constituents of the sample mixture migrate at different speeds based on their affinity to the stationary phase, allowing for their separation.
2. Gas chromatography (GC): GC involves the separation of volatile compounds by passing them through a column filled with a stationary phase. The sample is first vaporized and then carried through the column by a carrier gas. The compounds in the mixture interact differently with the stationary phase, leading to separation.
3. Thin-layer chromatography (TLC): TLC is a simple and inexpensive type of chromatography wherein a sample mixture is applied as a spot or streak onto a thin layer of adsorbent material (stationary phase) coated on a glass plate or sheet. The plate is then developed in a solvent, and the components of the mixture move at different rates, allowing for separation.
4. High-performance liquid chromatography (HPLC): HPLC is a more advanced version of liquid chromatography. It uses high-pressure pumps to force the sample mixture through a column with an extremely fine stationary phase. This results in faster separation with higher resolution.
5. Ion exchange chromatography: In this type of chromatography, the stationary phase has an affinity for charged molecules. The sample mixture containing ions is passed through a column containing an ion exchange resin, and the separation is based on the differing affinities of the ions to the stationary phase.
6. Affinity chromatography: In affinity chromatography, a stationary phase with specific affinity for a target molecule is used. The sample mixture is passed through the column, and the target molecule selectively binds to the stationary phase. The other non-target molecules are eluted, and the target molecule is then released from the column for further analysis.
7. Size exclusion chromatography (SEC): SEC separates molecules based on their size. The sample mixture is passed through a column filled with porous beads, which allow smaller molecules to enter the beads while larger molecules are excluded and therefore eluted faster.
8. Chiral chromatography: Chiral chromatography is used to separate enantiomers, which are mirror-image isomers of a molecule. The stationary phase used in this technique is chiral, and it selectively interacts with one enantiomer, allowing for separation.
9. Paper chromatography: Paper chromatography is a technique similar to TLC, but instead of a glass plate, a special paper is used as the stationary phase. The sample is applied as a spot or streak, and the separation is achieved by capillary action as the solvent moves up the paper, carrying the components with it.
10. Supercritical fluid chromatography (SFC): SFC uses a supercritical fluid (commonly carbon dioxide) as the mobile phase instead of a liquid or gas. The supercritical fluid exhibits properties of both liquids and gases, allowing for efficient separation of compounds.