Principle:

The technique of paper chromatography consists of a sheet of cellulose filter paper which serves as a stationary phase or separation medium. A small amount (usually a few micrograms) of solute is placed in a small area near the end of strip. A solvent is allowed to move from the end of the paper by capillary action and after equilibration for some fixed period, a solute migrates from its initial point of application. The components of mixture are separated completely or partially in distinct coloured zones or are located by the application of different reagents or by applying ultra-violet fluorescence.

At first, PC was considered as simply a form of liquid-liquid partition. The hydrophilic fibers of paper can carry (or bind) water in humid atmosphere such that a large percentage of water, say > 20% through weight, might be held in filter paper. Therefore, paper was considered to be the analog of a column containing a stationary aqueous phase whence solute molecules get partitioned between this water and the mobile immiscible organic solvent. At last, this model was considered to be too simple because separations were also obtained where mobile phase was miscible along with water or in other cases where it was just aqueous phase. Therefore, it cannot be considered as simply liquid-liquid partition mechanism. Alternatively, besides adsorption and hydrogen bonding, interactions among solutes and the cellulose support are involved. In During the pulping and carboxylate bleaching operations of paper and other ionizable groups are introduced within cellulose that makes the paper as ion exchanger.