A simultaneous determination of norephedrine, pseudoephedrine, ephedrine and methylephedrine in Ephedrae Herba and oriental pharmaceutical preparations by ion-pair high-performance liquid chromatography.

Abstract

A new, simple and rapid analytical method using ion-pair high-performance liquid chromatography was developed for simultaneous determination of norephedrine, pseudoephedrine, ephedrine and methylephedrine in Ephedrae Herba and oriental pharmaceutical preparations. A reversed-phase system consisting of an ODS chemically bonded silica gel column and a mixture of water, acetonitrile, sodium dodecyl sulfate and phosphoric acid (65 : 35 : 0.5 : 0.1) as the mobile phase was used. The four components extracted with the mobile phase could be completely separated within 15 min. The detection limits for the four components were 20 ng at a signal-to-noise ratio of 3 : 1.