If in-vial sample handling and analysis meth-
MATERIAL
ods work as intended, then VOCs present as va-
Each Gore-Sorber module consists of long
por, sorbed, or liquid (pure product or mixture)
(≈120-cm) hollow Gore-Tex membrane cord that
should be included in the measurement. There-
allows for installation and retrieval, and contains
fore, using in-vial sample handling and analysis
three separate granular Tenax-TA sorbent packs
procedures should increase the chances of estab-
(40 mg) positioned at one end. The Gore-Tex mem-
lishing a relationship with a vapor survey method.
brane, which also serves as a wrapping for each
To test this hypothesis, soil mass concentrations
pack, is an expanded polytetrafluoroethylene
established using an in-vial handling and analy-
(ePTFE), transparent to gases while preventing
sis method were compared to soil vapor analyte
direct contact of the sorbent with solid or aque-
amounts obtained with a passive collector, Gore-
ous matrices. Thus, during deployment in the
Sorber modules. Use of Gore-Sorber modules is a
field, the sorbent module is both wrapped and
relatively new method of performing a passive
sheathed in an inert, hydrophobic, microporous
soil gas survey for VOCs and some semivolatile
membrane, allowing only for the penetration of
organic compounds (Wrigley 1995). The sorbent
vapors.
present in the modules used in this study was
Tenax-TA, a material that has strong affinity for a
broad range of organic compounds, independent
of sample moisture. Experimentally, comparisons
EXPERIMENTAL
between the Gore-Sorber modules and well-es-
tablished grab sample VOC measurement meth-
Laboratory-fortified soil
ods were performed with both laboratory-forti-
The capabilities of the Gore-Sorber module,
fied and field-contaminated soils.
headspace gas chromatography (HS/GC), and
Table 1. VOC concentrations (g/g) established for vapor-fortified QA
soil samples.
Aqueous
Methanol
extraction
extraction
Tenax-TA TD/GC/MS***
(g/g)
HS/GC
PT/GC/MS
(g/g)
(g/g)
†
Analyte*
1d
9d
15 d
5.50.6**
5.80.55
TDCE
0.73
1.81
1.68
510.9
51.71.21
CDCE
8.1
15.6
14.5
895.0
85.31.58
CF
17.4
30.2
30.0
44.31.01
ND††
C-tet
11.7
18.4
18.2
630.4
61.71.49
Ben
14.2
26.4
24.2
8.00.3
8.30.44
TCE
3.24
4.56
3.99
6.30.31
1,1,2 TCA
ND
2.74
3.54
3.44
560.6
49.71.76
Tol
22.4
30.8
27.5
913.0
74.20.96
PCE
57.6
70.1
47.6
130.1
11.70.31
E-Ben
7.10
9.00
8.64
260.4
22.70.32
p-Xyl
13.5
16.9
15.6
410.7
36.90.85
o-Xyl
22.5
27.2
22.8
100.1
12.40.31
1,4 DCB
9.45
11.5
9.85
121.0
9.30.76
Napht
4.24
7.69
7.01
* TDCE, trans-1,2-dichloroethylene; CDCE, cis-1,2-dichloroethylene; CF, chloroform;
C-tet, carbon tetrachloride; Ben, benzene; TCE, trichloroethylene; 1,1,2 TCA,1,1,2
trichloroethane; Tol, toluene; PCE, tetrachloroethylene; E-Ben, ethylbenzene; p-
Xyl, para Xylene; o-Xyl, ortho Xylene; 1,4 DCB, 1,4 dichlorobenzene; Napht, naph-
thalene
** Mean and standard deviation of sample triplicates
† Equilibration period (days)
†† Not detectable by instrumental configuration.
*** Thermal desorption gas chromatography mass spectrometry.
2
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