Differences in collision-induced dissociation of the protonated molecules of isomeric alkyl phenols.

It is shown that isomeric ortho- and para-substituted alkyl phenols are characterized by significant differences in the collision-induced dissociation (CID) mass spectra of their protonated molecules formed at chemical ionization using methane as a reagent gas. Mass spectra of p-substituted isomers contain intensive peaks of characteristic ions [M + H − HO], which are absent from the spectra of o-isomers. Such principal differences in CID mass spectra permit us to distinguish ortho-alkyl phenols from other isomers without using the MS reference data and/or chromatographic retention parameters. [ABSTRACT FROM AUTHOR]