ABSTRACT
Chromatography in principle is based on the equilibrium distribution of a sample between two phases. The phases are composed of compounds other than the sample components. The separation of a sample by chromatography is achieved by the distribution of substances between mobile and stationary phases. Chromatographic methods may be classified according to type of mobile phase with the subdivision due to stationary phase used, method of sample movement through the bed, and technique. The basic nomenclature of column chromatography is shown by a hypothetical chromatogram. Chromatography is a separation method whose aim is the resolution of mixture components. The ability of a chromatographic system to separate two substances from the standpoint of thermodynamics is given by the quantity a, called selectivity ratio. The selectivity ratio compares the capacity factors of two components; or, simply, it is the ratio of adjusted retention volumes.
