Table 2. Subsample sets, holding times and storage conditions.
Experiment
Holding time and conditions
Analyte concentration
Day 0
Day 8
Day 14
22C†
22C
22C
(n=2) 3*
(n=2) 3
(n=2) 3
NaHSO4 - HS/GC
Day 0
Day 4
Day 8
Day 14
22C
22/4C
22/4C
22/4C
(n=3) 2
(n=3) 2
(n=3) 2
(n=3)
NaHSO4 - PT/GC/MS
Day 0
Day 5
Day 7
Day 14
Day 21
22C
22C
22C
22C
22C
(n=3)
(n=3)
(n=3)
(n=3)
(n=2)
MeOH immersion
Day 0
Day 14
Day 28
Day 42
22C
22C
22C
22C
(n=3)
(n=3)
(n=3)
(n=3)
† Storage temperature
* Number of subsamples sacrificed for analysis
The ampoules were transferred (with their sealed
cates from each storage condition were sacrificed
tips pointing down) to VOA vials and positioned.
and analyzed by HS/GC after holding periods of
4, 8 and 14 days (Table 2).
Effect of analyte concentration
The first experiment assessed if the analyte con-
PT/GC/MS
centration could inhibit the biodegradation of Ben
Fourteen subsamples were fortified for the low-
level PT/GC/MS holding time study (Table 1).
and Tol. Three sets (A, B, C) of six soil subsamples
These 1.50-g CRREL soil subsamples were acidi-
were vapor-fortified to different analyte levels
fied by adding 0.25 g of granular NaHSO4 to VOA
(Table 1). The storage period was initiated once an
ampoule had been broken and the soil completely
vials containing 3 mL of Type 1 water. As before,
dispersed into 30 mL of water contained in the
both the holding period and the acidification
VOA vial. Breaking the ampoule and dispersing
started once the ampoules' contents had been dis-
the soil was accomplished by hand agitation. Du-
persed inside closed VOA vials. For this experi-
plicates of these soil-water subsamples were sac-
ment the VOA vials were equipped with purge-
rificed and analyzed by HS/GC after 0, 8 and 14
and-trap adapter caps (Associated Design and
days at room temperature (22C) storage (Table 2).
Manufacturing Company, Alexandria, Virginia,
Model PT-6005-0002). Four sets of triplicates and
a set of duplicates were sacrificed and analyzed
Chemical preservation
by PT/GC/MS after 0, 5, 7, 14 and 21 days of stor-
with NaHSO4
age at 22C (Table 2).
HS/GC
Twenty-one soil-filled ampoules were fortified
MeOH immersion
for the holding time study of acidified subsamples
The MeOH immersion experiment was per-
prepared for HS/GC analysis (Table 1). These 1.50-
formed with 12 vapor-fortified soil subsamples
(Table 1). Each subsample was enclosed in a VOA
g subsamples of the CRREL soil were acidified by
vial with a Teflon-faced silicon septum cap, then
adding 0.25 g of granular NaHSO4 (pKa = 1.92) to
shaken to break the ampoule and disperse the con-
VOA vials containing 30 mL of Type 1 water. Both
tents into 10 mL of MeOH. Sets of triplicate
the holding period and the acidification started
subsamples were sacrificed after storage at room
once the ampoules containing the VOC-treated soil
temperature for periods of 0, 14, 28 and 42 days.
had been broken inside closed VOA vials with
Unlike the other experiments, the VOA vial con-
Teflon-faced silicon septa. One set of triplicates was
taining the methanolic-soil slurry was opened and
analyzed on day 0, while the remaining sets were
a 100-L volume was transferred into a VOA vial
split; half were stored at room temperature (22C)
and half were refrigerated (4C). A set of tripli-
containing 30 mL of Type 1 water by piercing the
3
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