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 [autonomic drugs] 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 4 components extracted with the mobile phase could be completely separated within 15 min. The detection limits for the 4 components were 20 ng at a signal-to-noise ratio of 3:1.