Chromatographic techniques for separating lipids

1 The principles of chronnatography are based on distribution between two phases, one moving, the other stationary. 

A chromatogram (so-named by its Polish inventor, Tswett, because he used the technique to separate plant pigments) consists of two immiscible phases. One phase is kept stationary by either being held on an inert microporous support or being itself a microporous or particulate adsorbent solid the other phase is percolated continuously through the stationary phase. Various phase pairs are possible although liquid-solid and gas-liquid are the most common. 

If we take any single substance and mix it with any of these phase pairs, it will distribute itself between the two phases, the ratio of the concentrations in the two phases (at equilibrium) being known as the partition coefficient. 

Only infrequently can every component of a complex mixture be resolved with one solvent system. However, by using two-dimensional development, i.e. first by one solvent system in one direction, then after drying the plate by running a different solvent at right angles, refined separations can be achieved. 

2 Gas-liquid chromatography is a particularly useful method for volatile derivatives of lipids 

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Chromatographic techniques for separating lipids 19 Table 2.2 Separation of complex lipids on silicic acid columns... 

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