Paper chromatography is a chromatography technique used to separate mix of chemical compounds into its unique compounds. Paper chromatography is used to educate TLC or other chromatography because it is extremely similar to TLC. All chromatography follow the exact same principle. Paper Chromatography is composed of two stages one mobile phase and one neighboring hive stage. The stationery phase a newspaper and the mobile gasoline is solvent. The compound mixture moves together with the mobile phase through stationery stage and divides depending on the different level of adhesion on the paper of each element in the sample or the chemical mixture. The paper chromatography is very like Thin layer chromatography. Difference is, rather than using a thin layer of silica on metal, it uses a special sort of chromatography paper as stationery phase.
Cellulose is a polymer of simple sugar, glucose. Cellulose includes -OH group like the silica or alumina on the TLC plate. The surface of cellulose is therefore very polar. So the chemicals can form hydrogen bond or may interact with van der waals dispersion forces and dipole dipole forces. Two way paper chromatography gets round the issue of separating out substances that have very similar Rf values. You can perfectly well do so with colorless chemicals but you must use quite a great deal of creativity in the explanation of what is happening! This time a chromatogram is made starting from one spot of mix put towards one end of the bottom line. It is stood in a solvent as before and left until the solvent front gets near the peak of the paper. If you look carefully, you might have the ability to understand that the large central place in the Paper Chromatography is partially blue and partially green.
Two dyes in the mix have the exact same Rf values. They could equally well, of course, both are the identical color in which case you could not tell if there was one or more dye within that spot. What you do today is to wait for the newspaper to dry out completely, and then rotate it through 90°, and produce the chromatogram again in another solvent. It is quite improbable that the two confusing stains are going to have the exact same Rf values from the second solvent in addition to the first, and thus the stains will proceed by another amount. The job of the second solvent front can be marked. If You Would like to identify the spots from the mixture, you Obviously cannot do it with comparison materials on exactly the exact same chromatogram as we Consider earlier with the pens or amino acids illustrations. It is possible, however, work out the Rf values for all those spots in both solvents, and then compare these values which you have measured for known chemicals under the exact same conditions.