ABSTRACT
During the early development of modern analytical chemistry, the study of natural materials was a primary concern of organic chemists and biologists. Chromatography (literally “color writing”) is a physical or physicochemical technique for separation of mixtures into their components on the basis of their molecular distribution between two immiscible phases. In modern instrumental applications of chromatography, the stationary phase is either a solid or a liquid, and the mobile phase either a liquid or a gas. In gas–liquid chromatography, the stationary phase is a high-boiling liquid, coated to a few percent by weight on an inert granular support such as silica, firebrick, diatomaceous earth, or Teflon. The theory of the influence of carrier gas on the separation process was given by van Deemter, Zuidweg, and Klinkenberg. The thermal conductivity detector or katharometer was one of the earliest gas chromatography detectors and utilizes the change in thermal conductivity of a gas mixture with composition.
