Methane‐enhanced negative chemical ionization mass spectrometry of s ‐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‐SCH 3 and 2‐OCH 3 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‐SCH 3 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] − .