1. Paper Chromatography

In this chromatography technique, the substance is analyzed by allowing the flow of solvents on a a specially designed filter paper. Due to capillary action, the solvent rises up on the paper and due to differential migration of the substances of a mixture, the separation is achieved.

In this type of chromatographic technique, Whatman Paper I is extensively used and this paper is available in different grades. The sample is prepared by using proper solvent and is applied on the paper as bands.

The sample is applied in drops on the spots with the help of a capillary tube. The spotting is done slowly and carefully in such a way that spots occupy only small areas.

Selection of Solvents:

Depending on the nature of the substances, the number of solvents are used for the separation. Using minimum number of solvents is preferable. Solvents used should be shaken well when more than one components of solvents is mixed. and by keeping in mind that, solvents should be used in specific rations to separate different substances.

Chromatogram Development
Image Source: Wikipedia

Location of Spots:

The developed paper is kept on a hot plate for drying for few minutes. There are two types of methods that can be used to locate the spots.

1) Physical Methods, where ultraviolet light and radioactive elements are used.

2) Chemical Methods, where locating reagents are used which may be liquids, solids or gases, here, the colorless spots are made colored by reagents to locate them.

Note: The method described above is ascending paper chromatography, where the solvent flows upwards on the paper by capillary action.
In descending paper chromatography, the solvent is allowed to flow down by gravitational pull on a paper by keeping the solvent at the top of the chromatographic chamber and by capillary action.

Next: 2. Thin Layer Chromatography (TLC)

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