Definition of Chromatography

Abstract

THE essence of the classical chromatographic method of Tswett¹ is presented by Ratchinsky² in the form of the following definition: “Any liquid or gaseous mixture of the substances is divided into its components during the process of its movement through a layer of sorbent, if there are differences in sorbtion interaction between the components of the mixture and the sorbent”. I believe the relative movement of the phases to be the important feature; in the case of the movement of the dispersed sorbent through a layer of a liquid or gaseous mixture the chromatographic process of Tswett will be inverted. In relation to the aggregate state of the dispersed sorbent the inverted method of Tswett thus embraces three varieties of chromatography: (1) suspension chromatography—when the solid dispersed particles of the sorbent settle or rise through the liquid or gaseous mixture^3,4; (2) emulsion chromatography—when the dispersed drops of liquid move through the liquid or gaseous mixture⁵; (3) foam chromatography when the dispersed bubbles move through the liquid mixture^6,7.