AchyranthosideI and Achyranthoside Ⅱ which were considered to be effective constituents from Achyranthes bientata BI were identified by electrospray ionization tandem mass spectrometric (ESI-MSn) methods after macro-porous adsorbent chromatographic separation.Their molecule masses were detected and ESI-MSn date were obtained, and fragmentation mechanisms were proposed. Their characteristic mass spectra can be use as fingerprint for the identification of AchyranthosideI and Achyranthoside Ⅱ. This method is ...