site was the environmental conditions under which this
Table 10. Comparison between GC-TID (field
instrument was operated during the ETV verification
and laboratory) and GC-ECD laboratory
test. The instrumentation was often exposed to direct
(Method 8095) results for tetryl in solvent
sunlight and the average temperature and humidity were
extracts of ETV soil samples.
83F and 58%, respectively. These environmental con-
ditions may further challenge this instrument's ability
Tetryl (mg/kg)
to detect HMX. Recently, it was observed that an oven
program of 145C, hold for 0.75 min., ramp to 170C
GC/TID
ECD
at 20C/min., ramp to 230C at 30C/min., ramp to
On site
Lab
Lab
245C at 10/min., improved the response for HMX
(sharper peak [Fig. 6]). Using this temperature program,
1.
15
12
11
several of the sample extracts were reanalyzed by GC-
2.
0.6
1.1
0.9
TID at CRREL. Samples were selected after receiving
3.
18
16
13
4.
3.0
3.4
3.8
the HMX values estimated by the reference laboratory.
5.
87
73
52
Table 12 shows that comparison of the HMX con-
6.
44
40
38
centration estimates for both laboratories is again
7.
35
33
27
very promising, as it was for the pre-demonstration
8.
23
24
19
samples.
Median and range of the % differences for analysis
pairs (ECD reference value, and the on-site GC-TID)
with analyte concentrations.
SUMMARY
Tetryl
During three separate field trials the GC-TID was
Median
25.3
observed to be a robust field analytical system capable
Range
33.3 to 67.3
of producing results comparable to Methods 8330 and
8095 for the determination of several explosives com-
pounds in soil. In particular, participation in EPA's
Environmental Technology Verification Program, a
a change in response between the 40 and 20 mg/L cali-
well-orchestrated and designed third-party evaluation,
bration standards was an anomaly unique to the ETV
demonstrated that this on-site method produced results
verification test. Foremost, it should be noted that be-
that were in very good agreement with those from a
cause HMX has a very low vapor pressure, it is one of
reference laboratory using Method 8330. Indeed, a close
the most difficult explosives analytes on the 8330
inspection of the data shows that the on-site GC-TID
analyte list to determine by GC (Walsh and Ranney
method provided more accurate results for reference
1998, Hewitt et al. 2000). Indeed, this compound tends
samples and showed better overall precision for the en-
to degrade in the injection port and as it passes through
vironmental and reference samples than the reference
the chromatographic system. A possible factor in the
laboratory using Method 8330.
poor performance of the GC-TID to analyze HMX on-
Table 11. Pre-demonstration results for HMX. Samples labeled C-1 and
C-2 are duplicates, as are D-1 and D-2.
Soil results for HMX (mg/kg)
Blank
C-1
C-2
D-1
D-2
Anticipated result
0
297
297
458
458
Acceptance range
0
151443
151443
240676
240676
*ORNL
<1.0
316
301
381
408
GC-TID
<2.5
220
380
460
400
*ORNL used Method 8330.
15
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