Studies on paper chromatography

A study with filter paper strips partially impregnated with the precipitating agent with or without colloid as the fixing agent reveals that in the case of spotted strips run in aqueous alcoholic mixture as the solvent, uniform bands of the precipitate are formed. In these cases, chromatographic observations such as measurement of ‘S’ and ‘Rf’ values is possible. Rhythmic structures can also be obtained with these strips when the reactant solution is used as the solvent. In the absence of colloids rhythmic structures are obtained at a high concentration and the bands obtained have to be washed and repeatedly dipped in hot water in order to clear the structure of rings present underneath. In the presence of colloid, rhythmic vertical bands are obtained at a much lower concentration and the clear interspaces are visible even without washing. Thus an independent method for obtaining rhythmic structures on filter paper with a technique very similar to chromatography has been developed.