Dimethyl ether and dimethyl‐d6 ether chemical ionization mass spectrometry of polynuclear aromatic hydrocarbons

Abstract

AbstractDimethyl ether (DME) chemical ionization mass spectrometry of a number of polynuclear aromatic hydrocarbons (PAHs) gave rise to a variety of fragment–molecule adduct ions resulting from ion–molecule reactions with the reagent gas. In 18 out of 22 cases, it was possible to differentiate among non‐nitrogenous PAHs on the basis of the identities and relative abundances of these adduct ions alone. For 14 nitrogen‐containing PAHs, adduct ion profiles were less distinct and differentiation among isomers was limited but possible in certain cases. With DME‐d6 as the reagent gas, the corresponding perduterio adduct ions were seen in substantially reduced abundances relative to their unlabeled counterparts, and there was no scrambling of deuterium. For the majority of the non‐nitrogenous PAHs and all of the nitrogen‐containing PAHs the most abundant ion was the methoxymethylene cation [M + 45]+. Collision‐induced dissociation studies of these ions demonstrated that fragmentation can take place according to three major pathways.