High-performance liquid chromatographic determination of alpha-acetyldigoxin in Digitalis lanata leaves.

An analytical method for the determination of alpha-acetyldigoxin in Digitalis lanata leaves by HPLC has been developed. The procedure consists of extraction of dry leaf powder with 50% methanol and cleanup by a Sep-Pak C18 cartridge prior to HPLC analysis. The quantitation is carried out by the incorporation of beta-methyldigoxin as an internal standard. HPLC is performed on an octylsilyl bonded silica column with acetonitrile/methanol/water (100/11/188, v/v). The effluent is monitored by uv absorption at 220 nm. The amount of alpha-acetyldigoxin per 100 mg of dry leaf powder is estimated at 5.55 +/- 0.21 micrograms (mean +/- SD). The average recovery of alpha-acetyldigoxin from added samples is 97.2%. The present method is sensitive, reliable, and relatively simple. Application of this HPLC method to the analysis of samples obtained by fermentation of the leaf powder is also demonstrated.