Evaluation of the alpha-phenylvinyl cation as a chemical ionization reagent for the differentiation of isomeric substituted phenols in an ITMS

Ion-molecule reactions between the α-phenylvinyl cation and isomeric naturally occurring phenols were investigated using a quadruple ion trap mass spectrometer. The α-phenylvinyl cation m/z 103, generated by chemical ionization from phenylacetylene, reacts with neutral aromatic compounds to form the characteristic species: [M + 103]+ adduct ions and the trans-vinylating product ions [M + 25]+, which correspond to [M + 103]+ adduct after the loss of benzene. Isomeric differentiation of several ring-substituted phenols was achieved by using collision-induced dissociation of the [M + 103]+ adduct ions. This method also showed to be effective in the differentiation of 4-ethylguaiacol from one of its structural isomers that displays identical EI and EI/MS/MS spectra. The effects of gas-phase alkylation with phenylvinyl cation on the dissociation behavior were examined using mass spectrometryn and labeled derivatives.