ABSTRACT
The very first detector used in chromatography by Tswett was the human eye and, to this day, the eye is still the most frequently used detector in thin layer chromatography. In Tswett's original experiments a number of plant pigments were separated and, because they were of colors that varied, the separated components were easily visible as colored bands in the column of absorbent. Today, chromatography is applied to almost all classes of chemical compounds, of which very few are colored, and consequently visual detection requires some chemical modification that will produce substances that will either reflect or absorb visible light. After separation on a thin layer plate, the individual substances contained in the mixture occur as invisible spots dispersed along the plate. If the chromatography was successful, the spots will be well separated from one another and if not, some spots will be merged with their neighbors.
