Abstract:

The electrospray ionization(ESI) mass spectrometry was used to study the fragmentation pathway of kaempferol. The fragmentation pathway of kaempferol was also theoretically studied by means of Density Functional Theory(DFT). The structures of all the fragment ions and the corresponding bond dissociation energies(BDEs) were analyzed by virtue of DFT at ROB3LYP/6-311++G(2d,2p)/B3LYP/6-31G(d) levels. Based on the comparison with the calculated BDEs, the structure and the origin of each fragment ion were determined, and then the whole fragmentation pathway was deduced. The calculated results show that the fragment ions at m/z 284.7, 256.7, 228.7, 210.7, 184.8, 168.7 and 150.7 of kaempferol mainly formed by the cleavage of the C ring. And the BDE of fragment ion at m/z 210.7 is the lowest, while the BDE of fragment ion at m/z 150.7 is the highest, suggesting that the former is evidently easier to form from the parent ion, and the latter is comparatively more difficult to form.

Key words: kaempferol,ESIMS,fragmentation pathway,BDE,quantum chemistry