📝 Chromatography

Task

🎧️ Listen to the recording and mind pronunciation of words.

Chromatography is a technique used to separate the components of a mixture. In chemistry, a component is one of the compounds or elements in a mixture. Chromatography works by dividing the components of a mixture between two phases - a stationary phase and a mobile phase. We call this partitioning.
In paper chromatography, the stationary phase is water absorbed onto the cellulose matrix of the paper. The mobile phase is usually an organic liquid or a mixture of solvents.
In thin-layer chromatography, a liquid solvent is allowed to flow up a piece of TLC plate coated with a solid. The mixture is placed in a small area on the plate and allowed to flow up the plate with the solvent. The distance travelled by a component compared to the solvent is called the retention time and can be used to identify the component.
In column chromatography a column is packed with a solid and a solvent moves down the column. The component is added to the solvent at the top of the column. The time it takes for a component to exit the base of the column is called the retention time and can be used to identify the component.
In gas chromatography a gaseous mixture is allowed to flow, under pressure and at high temperature, through a column lined with a solid or a solid coated with a liquid. Volatile liquids can also be vaporised and then allowed to flow through the column. The time it takes for a component to exit the column is called the retention time and can be used to identify the component.

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