Caffeic acid derivatives are one group of active constituents in Echinacea. Their distribution is variable and complex, and they may be used for identification of Echinacea species in commercial preparations. The characteristic chemical fingerprints of E. angustifolia, E. pallida and E. purpurea were examined by micellar electrokinetic chromatography (MEKC), a technique that has the advantage of higher resolution than either reversed-phase chromatography or capillary electrophoresis alone. The technique can be used to identify Echinacea species in combinations, or applied to quality control.
Pietta P, Mauri P, Bauer R. MEKC analysis of different Echinacea species. Planta Medica 1998; 64:649-652.
