APPLICATION OF THIN LAYER CHROMATOGRAPHY IN THE STUDY OF NATURAL PRODUCTS——Ⅱ.QUANTITATIVE DETERMINATION OF ERGOMETRINE ERGOTAMINE AND ERGOTOXINE

Application of the thin layer chromatographic method to the determination of ergometrine, ergotamine and ergotoxine in ergot has been studied. One gram of defatted ergot was accurately weighed and macerated with a mixture of 10 ml chloroform-methanol-ammonia (90:9:1) for 24 hours in a brown flask (50 ml volume). Five ml of the extract were pipetted into an Erlenmeyer flask (10 ml volume), placed in a vacuum desiccator and pumped to dryness at room temperature. The residue was dissolved in 0.25ml methanol, 0.1 ml being applied onto a 0.05×4.5×19 cm alumina layer and developed with a mixture of benzene-chloroform-absolute alcohol (7:3:0.5). Fluorescent spots of ergometrine, ergotamine and ergotoxine were located under UV light and separately transferred with a collector into reagent tubes. To each of these were added 0.5 ml ethanol, 1.5 ml 0.2N sulphuric acid, and 4ml van Urk's reagent. After shaking and standing for half an hour, the mixture was centrifuged and the clear blue solution determined colorimetrically. Analysis of an ergot sample, repeated six times, gave an average of 0.0255% for ergometrine, 0.0178% for ergotamine and 0.0143% for ergotoxine. Recovery of pure ergot alkaloids and experiments with added alkaloids showed high accuracy by this method. The procedure is simple and requires little organic solvents.