In this study

ultra performance liquid chromatography tandem three four quadrupole time-of-flight mass spectrometry (UPLC-Triple-TOF-MS) was used to discriminate three isomers(congmunosides VI

Ⅶ and B) in Aralia elata. Through the analysis of MS2 spectra of[M+Na]+(CE=90 eV) on congmunosides VI and Ⅶ (1 and 2)

both produced the same fragmentation ion peaks at m/z 981.498 2[Y0α+Na]+

819.439 1[Y0α-Glc+Na]+

527.161 4[C3β+Na]+

509.150 4[B3β+Na]+and 365.105 7[C3β-Glc+Na]+

while the MS2 spectrum of congmunoside B (3) of[M+Na]+(CE=90 eV) produced two different characteristic fragmentation ion peaks of m/z 671.198 2 and 689.208 7

corresponding to the[B4β+Na]+and[C4β+Na]+. Thus

the structure of congmunoside B(3) could be effectively distinguished with other two isomers of saponins(1 and 2) via[B4β+Na]+and[C4β+Na]+ions. Through the further analysis MS2 spectrum of[M+NH4]+and[M+H]+(CE=40 eV) for congmunosides Ⅵ and Ⅶ(1 and 2) yielded same ions at m/z 455.350 7 and 437.341 2

belonging to the[A-H2O+H]+and[A-2H2O+H]+. The aglycone of congmunoside Ⅵ(1) was echinocystic acid with the ion intensity ratio of[A+H-2H2O]+(m/z 437.34) to[A+H-H2O]+(m/z 455.35) ascribed to<1.The aglycone of congmunoside Ⅶ(2) was hederagenin with the ion intensity ratio of[A+H-2H2O]+(m/z 437.34) to[A+H-H2O]+(m/z 455.35) ascribed to >1.Based on the above fragmentations of[M+NH4]+and[M+H]+ions

congmunosides Ⅵ and Ⅶ(1 and 2) could be further distinguished. The study results demonstrated that three isomers from A. elata could be distinguished rapidly

easily and accurately by electrospray ionization tandem mass spectrometry.