Characterization of [M + 14] and [M + 28] anions formed during negative chemical ionization mass spectrometry of 2-chloro-s-triazines

The results of a systematic study of the [M + 14]−. and [M + 28]−. adducts observed in the methane-enhanced negative ion mass spectra of several 2-chloro-s-triazine compounds are presented. Using argon and methane-d4 as alternative enhancement gases for negative chemical ionization, as well as high-resolution accurate mass measurements, it is shown that the methane gas is the source of the species responsible for formation of the adducts. Data from collisionally activated decomposition tandem mass spectrometric experiments and from some model compounds suggest that the NH bond of the s-triazine is the site on the substrate for reaction with the methane gas.