Question

What is chromatography? Give an example.

Answer 1

Hint: Chromatography is a technique used for the separation of mixtures. The mixtures are separated by their distribution between two phases: Stationary phase and mobile phase.

Complete step by step answer:
Definition: The process of separating the components from a mixture by passing the mixture in form of solution or suspension through a stationary medium in which the components move at different rates.
Chromatography has two phases:
Mobile phase: The fluid in which the mixture to be separated is dissolved is known as mobile phase.
Stationary phase: The phase over which the mobile phase is passed is known as stationary phase.
Types of Chromatography: There are various types of chromatographic techniques as follows:
1.Paper chromatography
2.Ion-exchange chromatography
3.Gel-permeation chromatography
4.Affinity chromatography
5.Column chromatography
6.Thin layer chromatography
7.Gas chromatography (GC)
8.High performance liquid chromatography (HPLC)
Example: Consider paper chromatography.
In paper chromatography, paper sheets are used as the stationary phase and a mobile phase is allowed to run over the sheets. Paper chromatography can be used to separate different chemical substances having different rates of migration across the paper sheets.
The procedure for paper chromatography is as follows:
1.Select a suitable filter paper sheet as a stationary phase. Select the filter paper sheet depending on its pore size and the sample quality.
2.Dissolve the sample in a suitable solvent. The solvent should be the same as the solvent used in the mobile phase.
3.Spot the sample on the paper at a proper position with the help of a capillary tube.
4.Immerse the paper in the mobile phase. The mobile phase moves over the sample on the paper.
5.Dry the paper using a drier.
6.Identify the spots of the sample chromatogram.

Note:
The principle of chromatography is based on applying the mixture to a solid stationary phase and separating it by passing a mobile phase through it. The factors affecting the separation of the components of mixture are: adsorption of the components on the stationary phase, partition and differences in affinity and molecular weights of the components.