Topics - Chromatogram

Chromatogram The word chromatogram comes from two Greek words meaning color and writing (writing, the noun) which, together, literally means color writing. The term arose from the work of Tswett in his separation of plant pigments. Tswett separated some plant extracts on a calcium carbonate column using a dispersive solvent as the mobile phase. The different pigments aligned themselves along the column and, against the white chalk, gave a series of colored bands which Tswett called a chromatogram. In fact, the colored bands depicted the separation that he had obtained. From the same terminology the actual separation technique became known as chromatography vis color writing (writing the verb). To day all connotation between chromatogram and color has virtually been lost and a chromatogram is now understood to be a visual depiction of any chromatographic separation that has been developed. A chromatogram is usually a graph relating concentration (or mass per unit time) of solute leaving a chromatographic column, against time, and takes the form of a series of ever broadening peaks.. The first chromatograms of this form were traced on a recording milli-ammeter by Martin in the early 1950s. The recording milli-ammeter, however, was soon replaced by the potentiometric recorder. Today most chromatograms are presented on a computer screen and/or printed out on a computer printer.