Types of chromatography
This technique is mostly used for the separation of amino acids, sugars, sugars derivatives and also for the separation of chemicals by this type of chromatography.
Stationary phase in paper chromatography is Whatman No. 1 or Whatman No. 3 filter papers while Mobile phase is the mixture of water, organic solvents and of various additives.
In paper chromatography mixture of compounds to be separate is allowed to rise up and apply on the upward position (called ascending chromatography) at end of filter paper (usually 2 cm above the paper) by a capillary action or move down by a capillary action on the paper (called descending chromatography).
Solution of mixture to be separated applied on filter paper and migration of molecules present in solution occur and after some time paper is dried and dipped in solvent to visualize spots on paper with specific coloring reagents.
Since the speed of migrating molecules is depends on their relative solubility in the organic solvents, the total distance
covered by individual spot relative to the distance moved by the solvent is calculated and is known as Rf(Relative flow).
Sometimes, it is not possible and challenging to separate a complex mixture of substances by a single run with one solvent system. Like such a case, a second run is implemented by an other
solvent system, in a direction perpendicular to the first run. This is known as two dimensional
chromatography which increase the
separation of a mixture into the
individual components.
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