High Pressure Liquid Chromatography and Ultra‐high Pressure Liquid Chromatography of Plants: Basic Concepts

Abstract

High‐performance liquid chromatography (HPLC) is an essential method in plant analysis. Although it is primarily a separation method, it offers also the possibility of on‐line quantitative analysis during the separation. It can be used for both, the investigation of classes of compounds as well as of individual substances. HPLC is an instrumental method of great flexibility with regard to the separation conditions and to the detection principle. In any case, high pressure is needed; conventional HPLC acts up to about 350 bar. As the available pressure limits the speed of analysis and its separation power, the more recent technology of ultra high‐performance liquid chromatography (UHPLC) works at pressures up to 1000 bar. It allows very fast analyses or high peak capacity (i.e., the number of resolved compounds) or a combination of both demands. The separation environment can be aqueous, for example, in reversed‐phase or ion‐exchange HPLC, or nonpolar with organic solvents in adsorption chromatography, thus allowing a great choice of investigative principles.