DEFINITION & HISTORY OF CHROMATOGRAPHY
Chromatography is a modem technique used for the examination and separation of mixture of chemical substances. It facilitates the purification, isolation and comparison of compounds. It may be employed with all kinds of volatile and soluble substances, organic and inorganic, polar and non polar, and it may he adopted to use with various quantities under many different conditions.
According to the International Union of Pure and Applied Chemistry (IUPAC), in 1993 Chromatography is defined as, “A method for the separation of components of a sample, in which the components are distributed between two phases, one of which is stationary while the other moves in definite direction. The stationary phase may be a solid or a liquid supported on a solid or gel. The mobile phase may be gaseous or liquid.
The beginning of chromatography started with the work of Russian chemist and botanist Michael Semenovich Tswett (1872-1919) who in 1906 first used the term chromatography (colour. writing). He used the technique for separation of pigments based on selective adsorption. In 1937 Zechmeister published the first book on chromatography (paper and thin layer chromatography). Then in 1941 Martin and Synge introduced the idea of partitioning and in 1944 they replaced silica gel by the strips of paper. This led to the use of paper chromatography. James and Martin coined the idea of gas liquid chromatography in 1952. They got the Nobel prize on this work. Then the liquid-liquid partition chromatography was developed and it was based on a high performance liquid chromatography (HPLC). Later in 1959 Porath and Flodin used gels of cross-linked dextrans for separating the biological materials. Yet another achievement in the field of chromatography is the introduction of the technique of electrophoresis. The basis of separation by this* method is the migration of ions towards the oppositely charged electrodes under the influence of an electric field. This finds its use in the separation of peptides, purification of – enzymes, and isolation of nucleotides. Electrophoresis. however, is not considered to be included into chromatography these days.
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