Table 9. Average and standard deviation (n = 3) of analyte concentrations
for the sample spike and samples after various holding periods in VOA
vials under different storage conditions (D1, D2, and D5 at 4 2C, and
from D2 to D9 or D14 at 12 3C).
Analyte concentrations (g/kg)
12C storage after 2 days
4C storage
of 4C storage
Cmpd
Spike
D0
D1
D2
D5
D9
D14
TDCE
32
32a*
28b
26c
26c
26c
26c
1
1
2
1
1
1
1
88%†
81%
81%
81%
81%
CDCE
47
47a
40b
36c
32d
34c,d
35c
3
1
2
3
2
1
1
85%
79%
68%
72%
74%
Ben
30
30a
26b
23c
20d
24c
24c
1
1
1
1
1
2
1
86%
77%
67%
80%
80%
TCE
49
49a
49a
49a
50a
50a
52a
1
1
1
1
2
3
2
100%
102%
102%
102%
106%
Tol
32
32a
29b
25c
21d
25c
25c
1
1
1
1
1
2
1
91%
78%
66%
78%
78%
PCE
33
33a
33a
31a
32a
31a
31a
1
1
1
1
1
2
1
100%
94%
97%
94%
94%
E-Ben
23
22a,b
23a
18c,d
15d
19b,c
19b,c
1
1
4
2
3
2
1
105%
82%
68%
86%
86%
p-Xyl
23
21a,b
22a
18b,c
15c
19a,b
18b,c
1
1
2
2
3
3
1
105%
86%
71%
90%
86%
o-Xyl
28
28a
29a
26a
20b
27a
26a
1
1
2
1
3
1
2
104%
93%
71%
96%
93%
*Values with common letter are not significantly different at the 95% confidence interval
(ANOVA and Fisher's Protected LSD).
†Percent recovery relative to D0 sample concentration.
stored using En Core samplers or a modified sy-
screened or analyzed formally and the analytes
ringe and empty VOA vials. The first sample pre-
were not detected or a low concentration of VOCs
pared for analysis could be extracted with MeOH
was established, a collocated sample could be re-
and could be either screened or formally analyzed
moved from the freezer and run directly by a va-
using an accepted method. When screened and
por partitioning method of analysis using only an
found to have a high concentration of VOCs, an
aqueous solution. Because lower detection meth-
aliquot from the same sample could then be run
ods typically allow for only a single analysis to be
using an accepted method of analysis. If initially
performed per sample, a third collocated sample
analyzed by an accepted procedure and if the
would serve as a backup. One caveat when using
this approach is that a stirring bar should be in-
range, sample analysis would be finished. When
cluded in VOA vials prior to transferring a sample
17