High-performance liquid chromatographic determination of cardenolides in Digitalis leaves after solid-phase extraction.

For HPLC analysis of cardenolide glycosides of Digitalis lanata the separation of the main compounds from other constituents is useful. An improved method for doing this, based on solid-phase extraction on a C18 modified poly(styrene-divinylbenzene) polymer, is described. The presented assay permits quantitative estimation of more than 50 cardenolides in about 2 mg of dried leaf powder of Digitalis lanata with high speed and accuracy.