Objective: To study the fragmentation pathways of forsythoside A and forsythin by electrospray ionization mass spectrometry. Method: A syringe pump was used for the direct roop injections of reference compounds.Forsythoside A and forsythin were analyzed using LTQ orbitrap MS in positive ion mode.The first and multi-stage mass spectrum diagrams of forsythoside A and forsythin were obtained. Result: These were the fragmentation characteristics in the positive LTQ orbitrap MS. Forsythoside A was easy to lose C6H10O4 (rhamnose) or C9H8O4 (caffeicacid)

in the MS3 spectra there were two kinds of different sources of m/z 321 ion at the same time

We inferred that fragment ions were from m/z 501 or m/z 467 ion respectively losing caffeic acid or rat lee sugar cracking.Forsythin was easy to lose C6H10O5 (glucose)

in multi-stage fracture it was easy to lose H2O. We inferred that ester and glycosidic bond and hydroxyl may contribute to it in the molecular structure. Conclusion: It first reported the fragmentation pathways of forsythoside A and forsythin by LTQ Orbitrap-high resolution mass spectrometer in positive ion mode. The characteristic fragment ions were can be recognized as a rapid identification features of these compounds.Meanwhile

the study can provide accurate data support for further research of metabolites and modifying structure of these compounds.