Table 3. QA coupon wiping experiment using cotton ball moistened with 1.0
mL of acetone (g/coupon).
TNT
RDX
HMX
923 23
857 15
755 61
Spike*
Cotton balls (n = 3)
760 96
713 85
620 96
Aluminum
(82%)
(83%)
(82%)
763 46
677 25
560 20
Rusted steel
(82%)
(79%)
(74%)
*Spike, aliquots added directly to acetone
†Percent recovery relative to spike concentration.
better when the cotton balls were moistened with 1 mL
The results of wiping a hand grenade with a
of acetone. These analyte recoveries were much greater
solvent-moistened cotton ball are shown in Table 4. The
than the results obtained with the cotton balls shown in
surface that was wiped was covered with small, approxi-
Table 2. These higher analyte recoveries for cotton balls
mately 2-mm-high cones with small crevasses between
moistened with 1 mL of acetone can be attributed to
them. This initial range scrap trial showed that the cot-
ton ball wipes recovered on average 84% (3.2%) of
better control of the solvent wetting during the wiping
process. When 2 mL of solvent was present in the cot-
the TNT, RDX, and HMX that was present on the sur-
ton ball, as in the earlier experiment shown in Table 2,
face. This hand grenade contained Composition B,
the excess solvent ran off the top surface of the coupon
which is a mixture of TNT and RDX; HMX is a manu-
and spilled onto the table during wiping. This is a
facturing impurity (about 10%) in RDX.
mechanism for analyte loss.
Overall, cotton balls were superior to filter papers
Table 4. Hand grenade fragment wiping experiment using cotton
balls moistened with acetone (g/fragment).
TNT
RDX
HMX
Wipes
A
2300
1500
240
B
2800
1900
320
C
620
340
54
Fragement*
A (3.1 cm2)
420
330
35
B (4.1 cm2)
570
480
84
C (3.0 cm2)
92
50
BQ**
Wipe Recovery†
A
85%
82%
87%
B
83%
80%
79%
C
87%
87%
Average and standard deviation of analyte wipe recovery 84 3.2%.
*Amount of explosive remaining on fragment after wiping.
**Below quantitation.
†Percent of analyte present on metal fragment that was recovered in the
wipe sample.
8
Previous Page
