The term chromatography was originally used about 100 years ago by a Russian botanist, Mikhail S. Twsett (1872-1919) to describe the separation of bands of plant pigments (chlorophylls) extracted from green leaves. The process used with petroleum ether on calcium carbonate packed in a vertical glass column. Though chromatography (from the Greek word for "color writing") was descriptive of colored bands, most modern chromatographic methods do not involve separation of colored compounds. Chromatography now describes the process of separating compounds and ions by a variety of matrices on large numbers and types of columns. The International Union of Pure and Applied Chemistry has defined chromatography as follows: "A method, used primarily for separation of the compounds of a sample, in which the components are distributed between two phases, one of which is stationary while the other moves. The stationary phase may be a solid, or a liquid supported on...