Table 6. MDL study of 1-L reagent grade water samples fortified
with five target analytes and analyzed by solid phase extraction
and GC-NPD.
Found concentration (g/L)
Rep.
2,4-DNT
TNT
RDX
4ADNT
2ADNT
1
1.55
2.11
2.08
2.33
1.83
2
1.66
1.98
1.73
1.91
1.57
3
1.88
2.16
1.82
2.11
1.74
4
1.61
1.74
1.72
1.82
1.51
5
1.67
1.82
2.02
1.68
1.42
6
1.65
1.91
1.91
1.66
1.43
7
1.74
1.68
2.08
2.27
1.88
Mean
1.68
1.91
1.91
1.97
1.63
Std. dev.
0.106
0.181
0.156
0.273
0.190
MDL
0.32
0.54
0.47
0.82
0.57
of HMX was performed using a CN column. The
between batches of the extraction disks, or (2) a
results in Table 7 show that there was usually very
need to reduce the flow of the aqueous solutions
good agreement between these two methods of
through these membranes.
analysis, particularly for TNT and RDX. The
highly significant correlation (r2 = 0.998) between
Comparison of results for GC-NPD vs. RP-HPLC
these instrumental methods for all explosive
for field-contaminated soils
A method comparison was performed by ana-
analytes is also shown in Figure 5. In a few cases,
lyzing the same acetone extracts of field-contami-
there was poor agreement between the methods
nated soil samples by both RP-HPLC and GC-
and the failure of the GC-NPD analysis to iden-
NPD. To obtain determinations for all of the
tify a compound that was determined by RP-
analytes of interest, two RP-HPLC analyses were
HPLC analysis. This occurred for 2ADNT and
performed. With the exception of HMX, the com-
4ADNT when HMX was present at some two to
pounds were quantified by RP-HPLC analysis
four orders of magnitude higher in concentration,
using a C8 column. The RP-HPLC determination
and therefore they were not completely resolved
Table 7. Comparison between GC-NPD and RP-HPLC results for the solvent extracts of
field-contaminated soil samples.
Found concentration (mg/kg)
2,4-DNT
TNT
RDX
4ADNT
2ADNT
HMX
Sample
GC / HPLC
GC / HPLC
GC / HPLC
GC / HPLC
GC / HPLC
GC /HPLC
E
BDL†/ 0.027
1.3 / 0.72
0.50 / 0.43
ND / 0.43
0.38 / 0.45
NQ / 3000†
F
BDL / 0.032
2.4 / 2.1
0.25 / 0.22
ND / 0.52
0.27 / 0.53
NQ / 2800†
K
BDL / 0.045
28† / 25†
0.48 / 0.30
0.52 / 0.39
ND / 0.31
NQ / 1500†
M
5.5 / 4.5
140† / 150†
13† / 10
ND / 0.34
ND / 0.43
ND / NA
N
1.3 / 2.0
250† / 300†
120† / 130†
ND / 1.4
ND / 3.5
ND / NA
O
2.5 / 2.8
440† / 540†
1.7 / 2.1
2.7 / 0.93
2.5 / 1.6
ND / NA
T
0.92 / 1.2
0.39 / 0.68
0.28 / 0.30
ND / 0.16
ND / 0.19
NQ / 1800†
U
1.6 / 1.7
0.43 / 0.28
0.10 / 0.085*
ND / 0.11
ND / 0.11
NQ / 1100
*Below GC-NPD detection level.
†Above calibration curve.
ND Not detected.
NA Not analyzed.
NQ Not quantitated.
10
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