been available, and no third-party evaluations of
utes at very low cost using the highly portable kit.
the performance of this kit have been reported thus
This nonquantitative test kit was developed at Los
far.
Alamos National Laboratory and has been used
to screen soil to ensure that explosives contamina-
tion does not exceed the 10% levels prior to ship-
Additional considerations
Other important factors in the selection of an
ping to an analytical laboratory for analysis (Baytos
on-site method are the size and type of working
1991, Haywood et al. 1995, McRea et al. 1995).
area required, the temperature of the working area,
A semiquantitative method for identifying
the need for electricity and refrigeration, the
explosives using thermal desorption followed by
amount of waste produced, the need to transport
ion mobility spectroscopy has been developed for
solvents, the degree of portability, etc. Immunoas-
security applications (Rodacy and Leslie 1992). The
say methods are more sensitive than colorimetric
ion mobile spectroscopy method has been tested
methods to freezing and elevated temperatures,
on small quantities of soil samples and is currently
and the ambient temperature affects the speed at
being evaluated for soil extracts (Atkinson et al.
which color development takes place on some
1997). Research on this method is continuing.
immunoassay methods. Most tests are best run out
The use of a mobile laboratory screening
of the weather, in a van, field trailer, or nearby
method for detecting high explosives has been
building. High humidity has caused problems
described (Swanson et al. 1996). Ten-gram soil
with clumping of the zinc dust in the colorimetric
samples are extracted with 10 mL of acetone by
RDX tests.
shaking for 1 hour, and the extract is filtered.
Analysis is by high performance liquid chroma-
tography using a photo-array detector, and takes
Emerging methods
about 15 minutes per sample. It quantifies TNT,
and other literature reviewed
Several other screening procedures exist that
HMX, RDX, TNB, tetryl, 1,3-DNB, 2-AmDNT, 4-
have not been included in Table 3 because of the
AmDNT, 2,4-DNT, 2,6-DNT, and all three NTs at
limited information available on published meth-
detection limits of about 1 ppm.
ods or commercial availability.
A thermal desorption/Fourier transform infra-
The Naval Research Laboratory Center for Bio/
red spectroscopy screening technique was under
Molecular Science and Engineering has conducted
investigation by Argonne National Laboratory for
developmental research on an antibody-based
the U.S. Army Environmental Center. The esti-
continuous-flow immunosensor for TNT and RDX
mated detection limit was about 80 ppm without
and a fiber optic biosensor for TNT in water
further modifications to the procedure (Clapper-
(Whelan et al. 1993, Shriver-Lake et al. 1995). Both
Gowdy et al. 1992, Clapper et al. 1995), and no
methods have been evaluated as quantitative
further research is being conducted.
methods for explosives in groundwater at two sites
Fast determination (100 samples/10 h/person)
(Craig et al. 1996). These methods reportedly tol-
of explosives in soil (TNT, DNT, and NT) using
erate a certain percentage of acetone, and are cur-
thermal desorption followed by gas chromatog-
rently being evaluated for quantifying soil extracts
raphy/mass spectrometry analysis has been re-
containing explosives. Research of and instrument
ported. While no technical report on screening
development for these methods are continuing.
explosives in soil is available, the approach has
The U.S. Army has been sponsoring the devel-
been described in the literature for use with other
opment of a cone penetrometer capable of detect-
contaminants (Abraham et al. 1993, McDonald et
ing explosives in situ in soil, at levels determined
al. 1994).
to be 0.5 ppm in laboratory tests (Adams et
An initial study was completed on the use of a
al. 1995). Field tests have been conducted in which
simple thin-layer chromatographic method for use
a probe is hydraulically pushed to depth by a
as a confirmation test following colorimetric-based
20-ton truck, samples are pyrolized in situ, and
procedures (Nam 1997). This method can be ap-
a sensor selective to nitrogen oxide is used to
plied to extracts that test positive for TNT or RDX
detect explosives. Research on this method is
to discriminate among the several analytes that
continuing.
may be present.
A very simple spot test (colorimetric) kit can be
A study was recently published where x-ray
assembled to detect elevated levels of TNT and
fluorescence was evaluated for use in screening
RDX (>100 ppm) on filter paper swipes of surfaces
for metals-containing primary explosives (Hewitt
and soil. Samples can be analyzed in 1 to 2 min-
1997).
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