Influence of iron redox abilities on the electrospray ionization collision induced dissociation of iron complexes with methoxylated flavonoids

By using electrospray ionization mass spectrometry two types of iron complexes of methoxylated flavonoids were generated. Depending on the flavonoid structure, the complexes corresponded to the ions [(M-H)2+Fe]+ or [M2+FeCl]+, M stands for the flavonoid molecule. The unpaired electrons obtained as a result of methyl loss and iron reduction were shown to have essential influence on collision induced dissociation of ions [(M-H)2+Fe]+, which may be very useful for determination of the attachment position of methyl group. The loss of M molecule from [M2+FeCl]+ ion and the subsequent decomposition of [M + FeCl]+ enable differentiation between flavone and isoflavone, as well as gives valuable information concerning the positions of hydroxyl and methoxyl groups. [Display omitted] •Complexes of Fe3+ with methoxylated flavonoids were studied by ESI-MS•The complexes corresponded to the ions [(M-H)2+Fe]+ or [M2+FeCl]+•CID-MS/MS spectra of these ions enable the determination of the position of CH3