Principle of chromatography - Purification of organic compounds

The method of chromatography is based on the difference in the rates at which the components of a mixture move through a porous medium (called stationary phase) under the influence of some solvent or gas (called moving phase). So, this technique contains two phases- one is a stationary phase of large surface area whereas the second is a moving phase which is permitted to move slowly over the stationary phase. The stationary phase is either a liquid or a solid when the moving phase may be a liquid or a gas.