Page 288 - Advances in Forensic Applications of Mass Spectrometry - Jehuda Yinon

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100
530.4
95
[2M+75]
90
85
80
75
70
65
Relative abundance 55
60
50
45
40
35
30
25
[M+75] [2M+59]
20
302.6
[2M+35]
15 [M+59]
514.4
10 [M+45]
490.4
286.7
5
226.6 272
0
200 250 300 350 400 450 500 550 600 650 700 750 800
m/z
Figure 6.17 ESI mass spectrum of N 6 -RDX. (From Gapeev, A., Sigman, M.
15
and Yinon, J., LC/MS of explosives: RDX adduct ions, Rap. Comm. Mass Spec-
trom., 17, 943, 2003. © John Wiley & Sons Ltd. Reproduced with permission).
to be the origin of this adduct ion. When using purge-and-trap-grade
44
distilled methanol, instead of HPLC grade, the abundances of the [M + 45] –
and [M + 59] ions were found to be lower. 44
–
In APCI, which is a soft gas-phase ionization technique, part of the RDX
molecules decompose, yielding NO species which in turn cluster with a
–
2
–
second RDX molecule, producing abundant [M + NO ] cluster ions. This
2
44
–
was confirmed by using N -RDX. The ion [M + 45] in the APCI mass
15
6
15
spectrum of RDX was shifted by 7 mass units, when using N -RDX, which
6
supports the [M + NO ] interpretation. Addition of 0.1 mM formate or
–
2
chlorate in the mobile phase suppressed NO formation, thus making pos-
2
sible the formation of a desired adduct ion.
6.3.3 Nitrate Ester Explosives
Three well-known explosives in this group are pentaerythritol tetranitrate
(PETN), nitroglycerin (glycerol trinitrate, NG), and ethylene glycol dinitrate
(EGDN) (Scheme 7).
PETN is a white, crystalline explosive used as a base charge in blasting
caps and detonators, as the core explosive in commercial detonating cord, in
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