Methane-enhanced negative chemical ionization mass spectrometry ofs-triazines

A Hewlett-Packard 5988A quadrupole mass spectrometer was tuned systematically using a protocol for establishing the negative chemical ionization (NCI) operating conditions. The methane-enhanced NCI mass spectra of 22 s-triazines were then measured at ion source temperatures of 100°C and 250°C and are reported here. For 20 of the compounds the M−. or [M – 1]− ion was observed. Fragmentation patterns for 2-Cl, 2-SCH3 and 2-OCH3 substituted s-triazines are contrasted. For the 2-Cl substituted compounds fragment ions are more abundant at 250°C than at 100°C. For the 2-SCH3 substituted s-triazines, on the other hand, several fragment ions are noted at greater abundance at 100°C than at 250°C. In addition to the fragment ions observed, a number of unusual adduct ions are noted, including [M + 13]−, [M + 14]−, [M + 25]− and [M + 28]−.