(1937) n. In chemistry, analytical technique used for the chemical separation of mixtures and substances. A process in which a gas or liquid solution moves through a calibrated column containing a subdivided solid phase into which some components of the solution are absorbed, smaller molecules more quickly and thoroughly than larger ones. This is followed by pure carrier gas or solvent, the stream being monitored by a differential detector. Larger molecules emerge first, smaller ones later. The detector signal is proportional to the concentration of each species in the effluent. The process is mainly used for analysis of organic mixtures, but also for their separation. The name “chromatography” derives from the work of the Russian botanist N. Tswett, who first used the process to separate chloroplast pigments, obtaining colored bands on filter paper. Some variations of the process are gas chromatography(the gas mixture is passed through a porous bed, or through a capillary tube lined...