Abstract: | The three mono substituted N-(E)-3-(4-hydroxyphenyl)prop-2-enoyl]spermidines 1–3 have been studied by positive-ion electrospray-ionization tandem mass spectrometry (ESI-MS/MS). Because of the neighboring-group participation, the MS/MS of 1 + H]+ and 2 + H]+ are essentially similar, while compound 3 can be easily distinguished from 1 and 2 because of the characteristic ions at m/z 218. However, with the source collision-induced dissociation (source-CID) MS/MS technique, the compounds 1 and 2 can be unambiguously distinguished by the signal of the pyrrolidinium ion (m/z 72) from their daughter ion (m/z 275). The source-CID MS/MS of the labeled compound N-(4-aminobutyl)-N-(3-aminopropyl)-N-3-(4- hydroxyphenyl)prop-2-en15N]amide] (15N(4)]- 2 ) provide more information on the decomposition mechanisms and proved the occurrence of a partial transamidation reaction 2→1 during the measurement. |