Paper Chromatography- Definition, Types, Principle, Steps, Uses


Paper chromatography is a type of planar chromatography that uses a paper as the stationary phase and a liquid solvent as the mobile phase. It is a simple, inexpensive and widely used technique for separating and identifying the components of a mixture based on their different affinities for the two phases.

Paper chromatography can be used for qualitative or quantitative analysis of organic and inorganic compounds, such as amino acids, sugars, dyes, drugs, pesticides, etc. It can also be used for testing the purity of substances, detecting adulterants or contaminants, and studying biochemical reactions.

The principle of paper chromatography is mainly partition rather than adsorption. The paper contains cellulose fibers that hold water molecules as the stationary phase. The solvent moves up the paper by capillary action, carrying the sample with it. The sample components will separate according to how strongly they bind to the water molecules versus how readily they dissolve in the solvent. The more polar a component is, the more it will stay close to the water phase and move slowly up the paper. The less polar a component is, the more it will prefer the solvent phase and move faster up the paper.

The separation of sample components in paper chromatography can be visualized by different methods, such as staining with reagents, exposing to ultraviolet light, or measuring radioactivity or fluorescence. The degree of separation can be quantified by calculating the retention factor (Rf) for each component, which is the ratio of the distance traveled by the component to the distance traveled by the solvent front. The Rf value is a characteristic property of a component under specific experimental conditions, such as the type of paper, solvent, temperature, etc.

Paper chromatography has several advantages over other chromatographic methods, such as simplicity, low cost, high resolution, and minimal sample and solvent requirements. However, it also has some limitations, such as low accuracy, sensitivity, and reproducibility compared to more advanced techniques like high-performance liquid chromatography (HPLC) or gas chromatography (GC).