FAST-ATOM-BOMBARDMENT COMBINED WITH MASS-SPECTROMETRY FOR CHARACTERIZATION OF POLYCYCLIC AROMATIC-HYDROCARBONS

A new approach using fast atom bombardment combined with mass spectrometry to characterize polycyclic aromatic hydrocarbons (PAHs) in the range of 128-252 u molecular weight is described. Sulfolane was employed as a liquid matrix for these π-conjugated hydrocarbons. Bombardment of sulfolane solution of certain PAHs with an atom beam produces both radical cation (M+.) and protonated molecule [(M + H)+], with no evidence of fragmentation. Collisional activation of the fast atom bombardment-desorbed M+. ions, however, results in several structure-specific fragment ions. Structural differences in a few isomeric hydrocarbons can be detected using the [(M + H)+]/[M+.] abundance ratio and in the pyrene-fluoranthene pair by the B/E linked-field-collision-activated dissociation data. The [(M + H)+]/[M+.] was found to be compound-specific and correlated well with certain properties (resonance energy, proton affinity, and ionizing energy) of PAHs. © 1990 American Society for Mass Spectrometry.