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ERDC/CRREL TN-05-2
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BACKGROUND
Explosives are classified as "primary" or "secondary" based on their
susceptibility to initiation. Primary explosives, which include lead azide, lead
styphnate, and mercury fulminate, are highly susceptible to ignition and are often
used to ignite secondary explosives. Secondary explosives are much more
prevalent on military sites than primary explosives. They include trinitrotoluene
(TNT), 1,3,5-hexahydro-1,3,5-trinitrotriazine (RDX), and octahydro-1,3,5,7-
tetranitro-1,3,5,7-tetrazocine (HMX). These are used as the main destructive
explosive in ammunition (Thiboutot et al. 2002). TNT is the most commonly
used, either independently or in varying compositions where Composition B
contains TNT and RDX, and octol contains TNT and HMX. HMX is also found
as a manufacturing by-product of RDX.
The most commonly used organic chemicals for rocket, artillery, and mortar
propellants are nitroglycerin (NG) and nitrocellulose (NC). The residues most
often detected at the firing points are NG and dinitrotoluene (DNT) (Jenkins et al.
2003). These compounds also can be found downrange in rocket impact areas
because there often is unburned propellant remaining when the rockets detonate.
Characterization of impact areas and firing points consists of collecting
surface soil samples from a location of interest and placing these into a container,
either a bag or jar (Pennington et al. 2002). These samples may be either discrete
(one sample unit for the given area) or composite (multiple sample units from a
given area), and can range in weight from 50 to 5000 grams. Discrete samples are
generally small (50100g) and can be directly extracted with solvent without pre-
processing. Composite samples are generally much larger and require extensive
processing (i.e., sieving and grinding) to more evenly distribute the explosives
residue particle(s) throughout the sample. The composites are then subsampled to
obtain a representative fraction that can be extracted with solvent prior to instru-
mental analysis.
During sampling there are few indicators that an area may have high
concentrations of explosives residues. Munition fragments, non-detonated
munitions, discolored soil, discolored ponded water, or unburned propellant lying
in the vicinity of an impact area or firing point may indicate relative concentra-
tions. Yet with these indicators it is impossible to determine whether dilution of
extracts will be necessary prior to analysis. To quickly determine the approxi-
mate concentration of either a nitramine or nitroaromatic residue in a soil or
water sample, we have employed the use of an Expray Explosives Detection Kit
(Fig. 1). The cost of the full kit is approximately $U.S. 270 and it takes approxi-
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