Figure 3. Vapor signature of 1966 military-grade TNT.
not observe this phenomenon when standards of
TNT in acetonitrile were injected into the GC, and
we postulate that the metal housing surrounding
the SPME fiber catalyzed this reduction in the
presence of hydrogen in the injection port. When
helium was substituted for hydrogen as the
carrier gas, the two peaks corresponding to these
compounds disappeared. For samples where
2ADNT and 4ADNT were measured, the concen-
tration values were stoichiometrically converted
to, and added to, the TNT concentration.
An example GC-ECD chromatogram of the
equilibrium vapor above military-grade TNT
(Picatinny Arsenal, 1966 vintage), sampled with a
polyacrylate SPME fiber for 3 minutes, is pre-
sented in Figure 3. The major peaks correspond to
2,4-DNT, 1,3-DNB, 1,2-DNB, 2,3,6-TNT, and 2,4,6-
TNT, and several other isomers of DNT. These
results are consistent with those presented by
Murrmann et al. (1971) and Leggett et al. (1977)
for vapors from various samples of military-
grade TNT. Several of the early eluting peaks that
were reported as unknowns by Leggett et al.
(1977) were probably 1,2-DNB and 1,3-DNB.
The qualitative nature of the vapor signature in
the headspace above the buried TNT is modified
Figure 4. Vapor signature above low-moisture sand
held at 4C for 35 days.
TNT. Figure 4 presents the GC-ECD chromato-
gram for the SPME fiber (polyacrylate) sample of
is the reduction in the peaks corresponding to 2,4,6-
the headspace vapor above TNT that was buried
TNT and 2,3,6-TNT above the buried TNT, relative
in Ottawa sand for 35 days at 4C. The most obvi-
to the peak for 2,4-DNT and those corresponding to
ous difference between the vapor collected over the
the isomers of DNB. The differences in absolute
responses in Figures 3 and 4 are not meaningful