Quantitative analysis of ephedrine analogues from Ephedra species using 1H-NMR

Four ephedrine analogues such as ephedrine, pseudoephedrine, methylephedrine, and methylpseudo-ephedrine were determined by H-1-NMR from Ephedra species. In the region of delta 5.0-4.0, the signals of H-1 attached to the same carbon with a hydroxyl, were well separated from each other in CDCl3. The amount of each alkaloid was calculated by the relative ratio of the intensity of H-1 signal to the known amount of internal standard, 200 mug of anthracene. This method allows rapid determination of the quantity of four ephedrine alkaloids from Ephedra species. The amount of these alkaloids was in the range of 1.0-2.0% of dry weight depending on the plant materials.