paper chromatography

Paper chromatography
Presented by – Miss. Shruti Vilas Kharat.
SYBSc / FS13164
History-
Paper Chromatography (PC) was first introduced by German scientist Christian Friedrich Schonbein (1865).
PC is considered to be the simplest and most widely used of the chromatographic techniques because of its applicability to isolation, identification and quantitative determination of organic and inorganic compounds.
Definition-
Paper chromatography is an analytical method technique for separating and identifying mixtures that are or can be coloured, especially pigments. This can also be used in secondary or primary colours in ink experiments.
Principle behind paper chromatography-
Paper chromatography operate base on difference of compound diffusion in medium. Paper chromatography consist of paper as stationary phase, the carrier which could be water or alcohol. The carrier carry the compound through paper and since different compound do interact differently with the paper and had different diffusion in the liquid carrier medium so it was carry at different speed. Result is the mixture separated to different colour of compound.
Working-
Chromatography is a separation technique. On the piece of chromatography paper using pencil draw a line 1cm above the bottom of the paper. Make small spots of different colours or pigments at specific distance. Place this paper in a beaker with solvent. Take care that the spots should not dip in the solvent solution. As solvent absorbed it separates multiple components of the pigments.
The chromatography paper is called stationary phase. And the solvent is called mobile phase as it moves up on the chromatography paper.
Component which is more soluble travels greater distance up the chromatography paper. And the component which is less soluble travels shorter distance up the chromatography paper.

Retention factor (Rf) - In paper chromatography the results are represented by Fry value which represent the movement or migration of solute relative to the solvent front. Rf = Distance travelled by the solute Distance travelled by the solvent front
Larger the Rf value, more is the solubility of the component.
Smaller the Rf value, less is the solubility of the component.

Types of paper chromatography-
1. Descending Paper Chromatography-In this type, development of the chromatogram is done by allowing the solvent to travel down the paper is called Descending Chromatography. Here the mobile phase is present in the upper portion.
2. Ascending Paper Chromatography-Here the solvent travel upward direction of the Chromatographic paper. Both the Descending and Ascending Paper Chromatography are used for separation of Organic and Inorganic substances.

3. Ascending-Descending Paper Chromatography-It is the hybrid of both the above technique. The upper part of the Ascending chromatography can be folded over a rod and allowing the paper to become descending after crossing the rod.

4. Horizontal Paper Chromatography-It is also called as Circular chromatography. Here a circular filter paper is taken and the sample is given at the centre of the paper. After drying the spot the filter paper tied horizontally on a Petridish containing solvent. So that Wick of the paper is dipped inside the solvent. The solvent rises through the wick and the component get separated in form of concentrate circular zone.

5. Two-Dimensional Paper Chromatography-In this technique a square or rectangular paper is used. Here the sample is applied to one of the corners and development is performed at right angle to the direction of first run.

Uses and applications of paper chromatography-
Paper chromatography is specially used for separation of mixture having polar and non-polar compounds.
For separation of amino acids.
It is used to determine organic compounds, biochemical in urine etc.
In pharma sector for determination of hormones, drugs.
Sometimes used for evaluation of inorganic compounds like salts and complexes.