Mass spectra of seven related N-heterocyclics, introduced by direct exposure probe, were determined in electron impact (EI) and positive-and negative-ion chemical ionization (PCI and NCI) modes. Proton adducts were the predominant molecular ion species in the EI and PCI modes. In addition, a variety of fragment-molecule adduct ions were observed for each compound in one or more of the modes. The propensity of 1,3,9trinitrohexabydro-1,3,9triazine for fragment-molecule adduct formation was high in all three ionization modes. Fragmentation processes were documented by collision-induced dissociation experiments.
Table 3. Principal fragment ions of cyclic N-acetylamines and related nitramines mi.? (relalive abundance (%)) Compound El-PCI NCI lc 170 (6) (lo), 154 (36) (64). 143 (5) (15) 142 (4) (14). 129 (36) (56). 100 (100) (100) 225 (1) (8), 214 (1) (6). 213 (3) (2). 170 (3) (14), 156 (18) (as), 154 (6) (14), 143 (8) (48), 129 (16) (55). 113 (25) (61). 101 (23) (33). 100 (100) (100) 249 (2) (2). 244 (0) (2), 215 (6) (7). 202 (6) (6). 173 (55) (35). 170 (91) (97) 146 (49) (31). 128 (100) (67), 99 (69) (100) 239 (3) (14). 211 (4) (17), 197 (7) (26) 169 (8) (20). 168 (5) (14). 154 (90) (SS), 153 (14) (38). 126 (17) (53). 112 (76) (100). 1 1 1 (16) (48). 101 (100) (1) 183 (5) (71, 170 (6) (8). 169 (5) (71, 153 (22) (26). 141 (9) (10). 128 (9) (9). 126 (10) (11). 113 (100) (100). 99 (69) (57) 171 (lo), 154 (2), 143 (100) 101 (2). 100 (6) 242 (33). 214 (loo), 171 (49), 156 (17). 144 (69). 143 (100). 131 (21). 114 (26). 102 (56). 101 (35). 100 (41) 249 (100). 245 (29). 220 (94) 217 (62). 187 (19), 174 (23) 170 (11). 146 (22). 113 (41) 212 (87), 154 (13) 170 (10) 2c 2d 247 (l), 244 (3), 197 (100). 173 (87) 3 4 198 (13), 183 (26). 170 (28). 153 (6). 142 (100). 127 (4). 113 (19) a Numbers in parentheses denote relative abundances observed at two different source temperatures, 80 and 150ยฐC. respectively.