APPENDIX A: FIELD METHOD FOR RAPID SOIL VAPOR VOC ANALYSIS*
foil liners and hole-punched septums
I. Summary
A. Analytes: This method is suitable for estimat-
(slightly larger than o.d. of analyzer sam-
pling line).
ing the vapor concentration of VOCs in the field
3. 10-mL plastic syringes with their tips, rubber
using battery-operated equipment.
plunger cap, and holding post removed.
B. Matrix: This method is suitable for the esti-
4. 10-L syringe.
mation of total VOC concentration in unsaturated
5. Stock standard containing analytes of inter-
and saturated soil.
est diluted in MeOH. Note: A 1-mL volume
C. General Method: A 10-g (or larger) subsample
would be sufficient for the preparation for
of contaminated soil is manually dispersed within
a capped VOA vial with aluminum foil liner and
more than 200 working standards.
hole-punched septum. A soil VOC vapor deter-
mination is made by piercing the foil liner with
IV. Procedure
the sampling line of a total-VOC analyzer. Com-
Once an undisturbed soil surface is exposed for
parison of the analyzer response to a 0.2-mg/kg
sampling, 10-mL plastic syringes are used to
transfer 5-g plugs of soil to a VOA vial. After cap-
site specific working standard (same volume of
ping with an aluminum foil liner and hole-
soil as sample) to that of the sample serves as a
punched septum, disperse the soil by hand shak-
decision marker for how a collocated grab sample
ing for 10 to 15 seconds. Total VOC vapor is then
should be handled and prepared for laboratory
VOC analysis.
analyzed, after quickly checking for soil aggre-
gates adhering to the foil liner, by shoving the an-
alyzer 's sampling line through this barrier. The
II. Site-specific Working Standard
maximum instrumental response obtained within
A working standard is prepared using the con-
seconds of piercing the foil liner is compared to
taminant-free site-specific soil and the VOC(s) of
the typical response obtained for the site-specific
interest. The instrumental response to the work-
0.2-mg total VOC/kg working standards.
ing standard at the 0.2-mg total VOC/kg concen-
tration should be at least 10 above the normal
In accordance with the protocols recommended
by the SW-846 manual (U.S. EPA 1986), when the
background reading. To achieve this separation in
total VOC vapor response of the sample is greater
instrumental response, different volumes of soils
than that of the working standard, a collocated 5-g
will be necessary for different analytes and their
sample should be transferred with a subcorer (sy-
mixtures. For this study, 10 g was used for TCE
and 20 g for gasoline. A 4-L aliquot of the respec-
ringe) directly to a vessel containing 10 mL of
MeOH. If the response of sample is less than that
tive stock standard (0.53 mg TCE/mL or 1.1 mg
of the working standard, then a previously select-
gasoline/mL) was transferred to VOA vials con-
ed low-level in-vial procedure should be used.
taining soils to make the working standards.
Performing a total vapor analysis and collect-
Working standards should be prepared and used
ing a collocated grab sample from within the same
daily.
soil horizon and vicinity (5 cm) should take less
than 2 minutes. However, in addition to mini-
III. Apparatus and Chemicals
mizing the exposure period, care must also be tak-
1. Field-portable, battery-operated total VOC
en to limit soil structure disaggregation and con-
analyzer with a photo ionization detector
tacting of the soil transfer device with the solu-
and calibration gas cylinders.
tion, if present, in the collection vessels.
2. Clear glass 44-mL VOA vials with aluminum
* AEC protocol format.
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