Core samplers were placed in a refrigerator (4
of the syringe barrel was wiped before the final
2C). After two days, five were prepared for analy-
weight of sample was recorded. In the first experi-
sis and the 10 remaining En Core samplers were
ment the syringe contents were slowly extruded
transferred to a freezer held at 12 3C. A set of
into 40-mL VOA vials. After preparing 24 repli-
five was analyzed after five and the last set was
cates in this fashion, a 0.500-mL aliquot of an aque-
analyzed after 12 days of freezer storage.
ous solution containing the aforementioned nine
analytes at a concentration of approximately 50
Field experiments
mg/L was spiked onto the surface of each sample
Ten field experiments were performed with the
and the VOA vial was immediately capped. In
5-g En Core sampler. Each experiment consisted
addition to treating the 24 soil samples, three
of taking 10 or 12 samples in close proximity (Fig.
aliquots of the aqueous spiking solution were
6). Half of the samples were collected with a modi-
transferred to 40-mL VOA vials containing 5 mL
fied 10-mL syringe and half with En Core sam-
of MeOH to establish the concentration of the spik-
plers. Samples taken with the modified syringes
ing solution. These three solutions were prepared
served as the controls and were immediately trans-
after the first, thirteenth, and last soil samples were
ferred (in the field) to weighed VOA vials contain-
treated.
ing either 5.0 or 10.0 mL of MeOH, to establish the
After all the samples had been prepared, 5.00
D0 concentrations. A syringe was used for these
mL of MeOH was introduced to the first, thir-
samples so as not to deplete the supply of En Core
teenth, and last, so as to estimate the D0 concen-
samplers. Samples that were taken with the En
trations. The MeOH was added by piercing each
Core sampler were held for either two or seven
septum with a 23-gauge Luer Lok needle (B-D)
days at 4 2C, or for two days at 4 2C fol-
attached to a 5.00-mL glass syringe (SGE) with a
lowed by 12 additional days at 12 3C, prior to
Luer connector. Of the remaining 21 samples, nine
were stored at room temperature (21 2C), six
being extruded into weighed VOA vials contain-
were refrigerated (4 2C), and six were placed in
ing the appropriate amount of MeOH. Additional
a freezer (12 3C). After three days, MeOH was
information concerning this type of field experi-
ment has been presented elsewhere (Hewitt
introduced to sample triplicates that had been
1997b).
stored at room temperature. This process was re-
peated for sample triplicates stored at room tem-
perature, refrigerated, and frozen after holding
Empty VOA vials
Only laboratory studies have been performed
periods of seven and 14 days (Table 1).
In a second experiment, after obtaining 5.0 0.1 g
with the empty VOA vial approach to sample
transportation and storage. All experiments used
of soil in the syringe as described previously, a
soils from area with low (<0.01 mg/kg) concen-
pilot hole was made with a needle into the middle
of the soil plug. Then a 10-L glass syringe was
trations of TCE. After mixing in an aluminum pie
pan, discrete 5.0 0.1 g samples were transferred
used to transfer a 5.00-L aliquot of aqueous solu-
into empty 40-mL VOA vials by partially filling a
tion containing approximately 50 mg/L of the
5-mL modified syringe. The weight of each soil
same nine analytes into this cavity. Then the sy-
plug was established by taring the empty syringe
ringe barrel was inserted into the mouth of the
and adjusting the amount collected. The exterior
VOA vial, the sample extruded, and the vial was
~5 cm
Figure 6. Sampling pattern used for the En Core sampler trials.
8
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