Coring tool for the collection and transfer of discrete soil samples, e.g., dispos-
able 10-mL plastic syringes with the Luer Lok tip and rubber plunger cap re-
moved or an equivalent metal tube and plunger.
A portable photoionization detector (PID) analyzer with a 10.6-eV or greater
electrode discharge tube, digital display, inlet flow rate of greater than 300 mL/
min., and sample inlet tube of 3- to 4-mm o.d., at least 3 cm in length.
A 10-L syringe.
Reagent grade, water, i.e., water with no detectable VOCs, polypropylene gly-
col (PPG) and principal VOC(s) of site interest.
A cylinder of calibration gas for the PID, e.g., 100 ppm of isobutylene.
STANDARDS
A stock standard is prepared by transferring the VOC of interest into PPG. The
stock standard concentration should be based on the density of the analyte of inter-
est, so that a 1- to 3-L volume transferred to a 40-mL VOA vial containing 10 mL of
reagent water and 10 g of the site specific soil matrix results in a 0.2-mg VOC/kg
working standard.
Example:
Stock standard: 1.34* g/mL 2.0 L/ 2.5 mL = 1.1 mg TCE/mL
Working standard: 1.1 mg TCE/mL 1.8 L/ 10 g soil = 0.2 mg TCE/kg.
Immediately after spiking, these working standard vials are covered with a single
sheet of aluminum foil, which is tightly held in position with a septum with a hole
punched in the middle and a screw cap (Fig. A1). The vial contents of the working
standards should be thoroughly mixed by hand shaking, then transported to the
location of the sampling activity, stored out of direct sunlight, and allowed to equili-
brate for 1 hr prior to use. Working standards should be prepared daily. The PID
response to the working standard should be at least 10 greater than its response to
a blank (reagent water, contamination-free site-specific matrix, and appropriate
volume of PPG).
SAMPLE COLLECTION AND ANALYSIS
Prior to the field sampling episode, 10 mL of reagent water is added to the modi-
fied VOA vials. Once prepared, the VOA vials for screening samples should be
transported to the sampling location and stored with the working standards until
they are used. The location of samples taken for both screening purposes and labo-
ratory analysis should be as close as possible to each other (generally within 10-cm
radius), and from the same stratum. Prior to preparing (or exposing) a fresh sam-
pling surface, for instance opening a split spoon or scraping away the top layer of
a material, the cap and aluminum foil should be removed from the screening VOA
vial. After retrieving a discrete sample with a coring tool, the barrel should be in-
serted into the mouth of the screening VOA vial and the sample extruded. Once the
sample has been extruded, the aluminum foil and cap should immediately be re-
placed on the vial. If 10 g cannot easily be obtained in a single transfer, more than
one corer can be used, or two transfers with a single corer can be made. This collec-
tion and transfer process should take less than 10 seconds, and the sample weight
only has to approximate 10 g plus or minus 2 g.
*Density of TCE.
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