cumulate at the surface, aliquots were taken well
Teflon-faced butyl rubber septum (Wheaton). One
below the water/air interface, and the stainless
of these samples was prepared at the beginning,
steel needle was wiped prior to inserting into the
middle and end of the soil sample spiking pro-
ampoule's neck. Before transferring a spike, each
cess to estimate spiking solution concentration
ampoule was placed in a metal tension clamp so
and homogeneity. It took approximately 1 hr to
it could be heat-sealed with a propane torch im-
spike and seal the 42 soil samples, after which
mediately after spiking. Once sealed, every am-
each one was hand shaken, mixing their contents.
poule contained 1 g of soil and the moisture con-
The first, middle, and last spiked soil samples,
tent had been returned to 24%. In addition to
with and without NaHSO4, were selected for the
preparing the soil samples, a 200-L aliquot of the
initial analysis. For trials 1 through 3, the initial
spiking solution was placed into each of three
analysis was performed on the day of treatment
auto sampler headspace vials (22 mL, Tekmar)
(day 0). However, there was a 24-hr or greater
containing 15 mL of type 1 water. Each vial was
period of refrigerated equilibration between spik-
immediately capped with a crimp-top cap and
ing and the initial analysis for trials 4 and 5. After
the initial analysis, 12 sealed ampoules contain-
ing only fortified soil remained refrigerated (4C);
Table 2. Sample holding and storage conditions.
all of the other subsamples were held at room
For each trial, 27 ampoules contained soil and 15
temperature (22C). Triplicates from these three
contained soil and 0.25 g NaHSO4, prior to spiking.
subsample sets (22C preserved and unpreserved,
4C unpreserved) were selected at random and
Set 1,trial 1
Day 0
analyzed after various storage periods up to 28
Spiked: 42 soil subsamples.
days. The samples in ampoules were prepared for
Stored: 12 soil samples refrigerated (4C), 30 held at 22C.
analysis by placing them in auto sampler vials (22
Analyzed: 3 VOA vials, 3 soil samples, 3 soil samples pre-
mL) that contained 14 mL of type 1 water (MilliQ,
served with NaHSO4.
Millipore Corp.). After sealing with a crimp-top
Day 5, 9, 14, 21
cap, each vial was vigorously hand shaken, caus-
Analyzed: 3 samples stored at 4C, 3 samples stored at 22C,
ing the ampoule to break and allowing the treat-
3 samples preserved with NaHSO4.
ed soil to be completely dispersed. To facilitate an
Set 2, trial 2
HS equilibration condition, shaking continued for
Day 0 (same as set 1, trial 1 )
another two minutes after the ampoule was bro-
Day 4, 8, 14, 28 (same as set 1, trial 1 )
ken, and prior to placing in the auto sampler for
analysis. Table 2 describes the holding and stor-
Set 3, trial 3
age conditions for each of the five trials covered
Day 0 (same as set 1, trial 1 )
in this study.
Day 3, 6, 13, 28 (same as aet 1, trial 1 )
Set 1, trial 4
Day -2
ANALYSIS
Spiked: 42 soil samples
All samples were analyzed with a headspace
Day 0 (after two days storage at 4C).
Stored: 12 soil samples remained refrigerated (4C), 30 held
auto sampler (Tekmar 7000), coupled to a GC (SRI,
at 22C.
model 8610-0058) equipped with a 15-m DB1 0.53
Analyzed: 3 VOA vials, 3 soil samples, 3 soil samples pre-
capillary column. The auto sampler parameters
served with NaHSO4.
were 1) platen temperature 25C and equilibra-
tion time 20 min., 2) loop size 1 mL, 3) loop and
Day 1 , 2, 3, 5
Analyzed: 3 samples stored at 22C
line temperature 100C, 4) pressurization time 0.20
min., 5) pressurization equilibration time 0.10 min.,
Day 5, 13, 21, 28
Analyzed: 3 samples stored at 4C, 3 samples preserved with
6) loop fill time 0.25 min., 7) loop equilibration
NaHSO4.
time 0.10 min., 8) inject time 1.0 min. and 9) vial
pressurization 7.5 psi. The HS sample was trans-
Set 4, trial 5
ferred to the GC for separation and flame ioniza-
Day -1
tion detection (FID). For the first two sets of ana-
Spiked: 42 soil samples
lytes (set 1 and 2), the GC temperature sequence
Day 0 (after one day storage at 4C). (same as set 1, trial 4)
started with the injection, stayed at 40C for 1
min., then increased to 100C in 6 min., and was
Day 5, 10, 14, 28 (same as set 1, trial 1 )
3
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