Liquid Chromatography - Introduction 1


Liquid chromatography (LC) was the first type of chromatography to be discovered and, in the form of liquid-solid chromatography (LSC) was originally used in the late 1890s by the Russian botanist, Tswett (1) to separate and isolate various plant pigments. The colored bands he produced on the adsorbent bed evoked the term chromatography (color writing) for this type of separation. Initially the work of Tswett was not generally accepted, partly due to the original paper being in Russian and thus, at that time, was not readily available to the majority of western chemists and partly due to the condemnation of the method by Willstatter and Stoll (2) in 1913. Willstatter and Stoll repeated Tswett's experiments without heeding his warning not to use too "aggressive " adsorbents as these would cause the chlorophylls to decompose. As a consequence, the experiments of Willstatter et al. failed and their published results, rejecting the work of Tswett, impeded the recognition of chromatography as a useful separation technique for nearly 20 years.

In the late 1930s and early 1940s Martin and Synge introduced a form of liquid-liquid chromatography by supporting the stationary phase, in this case water, on silica gel in the form of a packed bed and used it to separate some acetyl amino acids. They published their work in 1941 (3) and in their paper recommended the replacement of the liquid mobile phase with a suitable gas which would accelerate the transfer between the two phases and provide more efficient separations. Thus, the concept of gas chromatography was born. In the same paper in 1941, Martin and Synge suggested the use of small particles and high pressures in LC to improve the separation which proved to the critical factors that initiated the development of high performance liquid chromatography(HPLC).

"Thus, the smallest H.E.T.P. (the highest efficiency) should be obtainable by using very small particles and a high pressure difference across the column".