ABSTRACT
The interest of micellar electrokinetic chromatography (MEKC) and microemulsion electrokinetic chromatography (MEEKC) for the resolution of four cardiac glycosides is demonstrated. First, the influence of some parameters on the resolution of the solutes in MEKC such as the concentration of the surfactant, pH, addition of organic modifiers and urea is discussed. Then, results are compared with those obtained in MEEKC using different microemulsion compositions. Results indicate that MEEKC possesses several advantages over MEKC for the separation of relatively hydrophobic compounds such as digitalic compounds. First, microemulsions allow a better manipulation of the migration time window and of the retention of the solutes. Moreover, efficiency is improved with shorter analysis time.
Subject(s)
Cardiac Glycosides/analysis , Cardiotonic Agents/analysis , Electrophoresis, Capillary/methods , Micelles , Acetyldigitoxins/analysis , Acetyldigitoxins/chemistry , Acetyldigoxins/analysis , Acetyldigoxins/chemistry , Cardiac Glycosides/chemistry , Cardiotonic Agents/chemistry , Deslanoside/analysis , Deslanoside/chemistry , Digoxin/analysis , Digoxin/chemistry , Emulsions , Hydrogen-Ion Concentration , Spectrophotometry, UltravioletABSTRACT
An extraction process is reported that employs a near-supercritical mixture of CO2 and MeOH to extract the cardiac glycoside, digoxin, from the Digitalis lanata leaf. The method development of the sample preparation procedure is presented in detail, and reasons for trends that occur in the natural products extraction are given.
Subject(s)
Acetyldigoxins/analysis , Digitalis/chemistry , Digoxin/analysis , Plant Leaves/chemistry , Plants, Medicinal , Plants, Toxic , Acetyldigoxins/isolation & purification , Chromatography, High Pressure Liquid , Digoxin/isolation & purification , Hydrolysis , Plant Extracts/analysisABSTRACT
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.
