Tuesday, 23 April 2013

Paper Chromatography

Let us see Paper Chromatography, (Stationary phase-Paper, Sample is applied to the edge of Paper) It is  Chromatographic method. The paper chromatography is  used for the testing of purity of compounds and identifying substances and a very useful method as it is quick and very small quantities of materials used. This method is used to separate mixture of compounds which are coloured, for example  coloured pigments can be separate out by this process. Like other chromatographic methods , even here stationary phase and mobile phase are used and based on the properties of the compound mixture they are separated out.

Stationary phase used here is a very thin and uniform absorbent paper and the Mobile phase is a suitable liquid or solvent mixture. Now here the spot of sample is applied on the stationary phase, then the mobile phase is passed through the stationary phase which carries the spot sample mixture along with it. Based on the amount of distance traveled by the sample mixture the compound is identified. Rf value is used to measure the sample traveled on the paper. The principle is same as thin layer chromatography.

Paper chromatography definition
Paper Chromatography

You can see the three samples which are applied at the base line then after some time mobile phase is passed through the  paper chromatography the mixture started to travel in upward direction and , you can also see the different colors separated out. Now based on the Retention factor (Rf value) the sample is identified out. Different mixture have different rf value and hence this paper chromatography will help you to find out the exact compound mixture.