Investigations of the fragmentation behavior of 11 isoflavones with ESI-IT-TOF-MSn
The fragmentation behavior of isoflavones was studied using electrospray ionization-ion trap-time of flight mass spectrometry (ESI-IT-TOF-MSn). It was found that the isoflavone glycoside bond was easily broken. The fragmentation occurred mostly on the C-ring, and the fragment ions of A1,3+ produced bythe RDA cracking will predict the hydroxylation replacement on A-ring or B-ring. In addition, four carbonyl groups on the C-ring were fragmented through neutral loss of 28 (-CO). A and B-rings primarily lose substituents which including a neutral losses of 32 (-CH3OH), 16 (-CH4), or 16 (-O), and 18 (-H2O). A-ring in the presence of adjacent hydroxylation, also easily made to be a neutral losses of 28 (-CO) or 18 (-H2O). It is likewise common to see methoxy replaced with a neutral losses of 16 (-CH4) or 32 (-CH3OH) in B-ring, also the hydroxylation on benzene ring can occasionally results with the neutral loss of 28 (-CO).