Chromatography is one of the most widely used means of performing chemical analyses in the world. Russian botanist Mikhail Tswett is credited with discovering the technique of chromatography. Using alcohol as a mobile phase and chalk as a stationary phase, Tswett was able to separate various plant extracts.
Figure 1. Example of Tswett’s Experiment
Figure 1 shows how Tswett’s experiment may have taken place. The vertical columns represent the chalk. At 0 minutes a mixture of plant extracts was placed at the top of the column. A steady rate of alcohol was then added to the top of the column. Over the next 10 minutes, as the extracts were pushed through the chalk by the alcohol, the extracts were separated into distinct bands.