Structural analyses of carbon chains in 5-alk(en)ylresorcinols of rye and wheat whole flour by tandem mass spectrometry

The locations of double bonds and the linearity of each carbon chain in 5-alk(en)ylresorcinols present in rye and wheat whole flour were determined from collision-activated dissociation (CAD) spectra by tandem mass spectrometry. Among the determined alk(en)ylresorcinols, eleven alkenylresorcinols (C-17 to C-23) and four alkadienylresorcinols (C-19 to C-25) had not been previously identified. In this study, we found that identification of a radical-anion fragment peak due to a simple allylic cleavage on the methyl side was essential for determining the locations of double bonds in positionally isomeric alkenylresorcinols. In addition, an analysis of the CAD spectra of lithium-adduct cations as precursor ions was useful for determining the locations of the homoconjugated (Z,Z)-diene group in alkadienylresorcinols.