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APCI
Abundance
227
380000
360000
340000
320000 M-
300000
280000
260000
240000
220000
200000
180000 226
160000
140000
120000
100000
80000
60000 210
40000 182 197
20000 97 125 137 152 167 244 258 236 327 350
m/z-> 0
100 120 140 160 180 200 220 240 260 280 300 320 340
Electrospray
Abundance
226
55000
(M-1)-
50000
45000
40000
35000
30000
25000
20000
15000
208
10000
5000 183 239 288 393
102 137 164 255 297 335 369 381 430 445
m/z-> 0
100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420
Figure 6.3 APCI and ESI mass spectra of TNT. (From Schilling, A. B., The
analysis of explosives constituents and metabolites with electrospray and APCI
LC/MS, presented at 44th ASMS Conference on Mass Spectrometry and Allied
Topics, Portland, OR, 1996. With permission).

propanol–water. The isopropanol was kept constant at 10% through the run;
methanol was held at 30% for the first 25 min, before starting a 2-min linear
gradient from 30 to 85%, at which it was held for 3 min. The mobile phase
was returned to its initial condition within 2 min and held for 3 min before
starting a new run. For the standard mixture of four of the DNT isomers,
three DNB isomers and TNB (Schemes 2 and 3), the separation was carried
out by an isocratic run of methanol–water (57:43). Figure 6.5 shows the mass
chromatograms of the TNT, DNB, DNT, and TNB isomers. When 2,5-DNT
was included in the standard mixture of TNB, DNB, and DNT, a linear
gradient elution with methanol–isopropanol–water was used, keeping a con-

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