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A simple, sensitive, and reliable method using gas chromatography (GC)-mass spectrometry (MS) is developed for the simultaneous determination of ephedrine alkaloids and 2,3,5,6-tetramethylpyrazine (TMP) in  Ephedra sinica  Stapf. The sample is extracted with ethyl ether and submitted to GC-MS for identification and quantitation without derivatization. The column used for GC is an HP-5 (30.0 m × 250 µm × 0.25 µm, 5% phenyl methyl siloxane), and the carrier gas is helium. The detection limits for ephedrine, pseudoephedrine, and TMP are 0.4 ng, 0.7 ng, and 0.02 ng (signal-to-noise ratio of 3), respectively. The reproducibility of the total procedure is proved to be acceptable (RSD &lt; 2%), and the recoveries are above 93%.

Separation and Determination of Ephedrine Alkaloids and Tetramethylpyrazine in Ephedra sinica Stapf by Gas Chromatography-Mass Spectrometry