30
2.5% ACN
1.0%
0.5%
20
Acidified
Control (%)
10
Unacidified
Control (%)
0
20
40
Storage Time (days)
Figure 4. Stability of TNB as a function of the acetonitrile concentration
for samples also acidified to pH 3.5.
50
pH 2.0
40
3.5
30
20
Unacidified
10
0
20
40
Storage Time (days)
Figure 5. Stability of TNT in samples acidified to pH2, pH 3.5, and left
unacidified.
34 days were 7.6 g/L, 6.3 g/L, and <d, respec-
of ACN of 7.5% (Fig. 3) or 10% (not shown), which
appeared to be as effective as acidification to pH 2
tively. Acidification did reduce the rate of loss of
for TNB stabilization in this matrix.
TNB relative to samples containing the same per-
The concentration at which ACN was effective
cent ACN but without acidification (Fig. 3 and 4).
in retarding TNB loss was reduced when the
The effects of the various chemical treatments
samples were also acidified to pH 3.5 with acetic
were very similar for TNT, except the rates of
acid (Fig. 4). For this combination, no observable
change were reduced in all cases. For example,
TNB loss or increase in 3,5-DNA concentration
after four days, the TNT concentration in the con-
trol sample was reduced from 41.3 g/L to 26.5
was found for samples containing ACN concen-
g/L for a reduction of about 36% (Fig. 5). For
trations of 2.5% or higher. For samples containing
1.0%, 0.5%, and 0.1% ACN, TNB concentrations at
TNB over the same period, the reduction was about
7
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