Table 1. Methods for the detection of explosives recommended by the U.S. EPA.
Method no./vendor
Analyte*: Interferences and cross-reactivities
Method 8515 / EnSys RIS
TNT: TNT = TNT + TNB + DNB + DNTs + tetryl
Method 8510 / EnSys RIS
RDX: RDX = RDX + HMX + PETN + NQ + NC + NG
Method 4050 / D TECH
TNT: tetryl = 35%†; TNB = 23%; 2AmDNT = 11%;
2,4-DNT = 4%
Method 4051 / D TECH
RDX: HMX = 3%
Methods 8330
TNT, TNB, DNB, 2,4-DNT, 2,6-DNT, Tetryl, 2AmDNT
4AmDNT, NT (3 isomers), NB, RDX, HMX
Method 8095
TNT, TNB, DNB, 2,4-DNT, 2,6-DNT, Tetryl, 2AmDNT
4AmDNT, NT (3 isomers), NB, RDX, HMX, PETN,
NG, 3,5-DNA
*Analyte abbreviations and names:
TNT--2,4,6-trinitrotoluene;
TNB--1,3,5-trinitrobenzene;
DNB--1,3-dinitrobenzene;
2,4-DNT--2,4-dinitrotoluene;
2,6-DNT--2,6-dinitrotoluene;
Tetryl--Methyl-2,4,6-trinitrophenylnitramine;
2AmDNT--2-amino-4,6-dinitrotoluene;
4AmDNT--4-amino-2,6-dinitrotoluene;
NT--ortho, meta, and para nitrotoluene;
3,5-DNA--3,5-dinitroaniline;
NB--Nitrobenzene;
RDX--Hexahydro-1,3,5-trinitro-1,3,5-triazine;
HMX--Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine;
PETN--Pentaerythritol tetranitrate;
NQ--Nitroquanidine;
NC--Nitrocellulose;
NG--Nitroglycerin.
†Percent cross-reactivity
injection port, and an internal air compressor. The in-
evaluated for use with a field-portable GC. However,
strument sells for less than K, but also requires a per-
overall they were not found to be as sensitive or as se-
sonal computer (
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K) for controlling the oven tempera-
lective as the TID detector (Hewitt and Jenkins 1999,
ture program and for the collection and handling of data.
Hewitt et al. 2000). The TID is an electrically heated
Separations were performed on a Crossbond 100% dim-
emission source made in the shape of a bead composed
ethyl polysiloxane column, 15-m 0.53-mm i.d., 1.5
of an alkali metal impregnated into a ceramic material
m (DB-1). Injections of 1 L were made manually
(Patterson 1986). When compounds containing nitro
with a 10-L glass syringe (SGE) equipped with an extra
functional groups impinge on the bead's surface, they
long needle (6.0 to 7.0 cm). The oven temperature pro-
are ionized, the negative ions move to a collector elec-
gram, carrier gas and flow rate, detector voltage, and
trode, and the ion current at this electrode is measured
the use of a supply of air to the detector were specific
with an electrometer. Therefore, this detector will re-
spond not only to nitroaromatics and nitramines, but to
to the analytical objectives of the different field trials.
nitrate esters as well. This report compares on-site GC-
For the first field trial the target analytes were TNT,
TID results to those obtained in the laboratory using ei-
2,4-DNT (2,4-DNT is a manufacturing impurity in the
ther Method 8330 or 8095, for three different field trials.
production of TNT), and two environmental transfor-
mation products of TNT, i.e., 2AmDNT and 4AmDNT.
For this group of analytes a high level of sensitivity is
METHOD AND MATERIALS
achieved when using the settings originally recom-
mended by the instrument manufacturer. Air was used
as the carrier gas and the potential of the TID bead was
In this study we used a field-transportable SRI Model
set at 2.80 V (Hewitt et al. 2000). The air pressure for
8610C gas chromatograph equipped with a heated
the on-board air compressor was set at 10 psi for a car-
(250C) TID detector, a heated (225C) on-column
rier gas flow rate of approximately 25 mL/min. The
2
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