16
ERDC/CRREL TR-02-12
Volatile organics
This section describes the methods used for the VOCs in the high-level and
low-level VOC studies and for TCE in the field study. Samples were collected in
glass 40-mL VOA vials, being careful to eliminate any bubbles or headspace, and
sealed with Teflon-lined caps. These vials were stored in a refrigerator until the
samples were analyzed. At that time, an aliquot was transferred to a glass, 1.8-
mL autosampler vial using a glass Pasteur pipet. Most samples were analyzed
within 24 hours and all within 48 hours.
Analytical determinations were performed using reversed-phase HPLC (RP
HPLC) using the same modular system that was employed in the explosives
study. The UV detector was set at 215 nm, and separations were obtained on a
25-cm 0.46-cm (5-m) LC-18 column (Supelco) and eluted with 2.0-mL/min.
of 65/35 (v/v) methanol/water. The detector response was obtained from the
digital integrator operating in the peak height mode.
For the high- and low-level VOC studies, 2000 mg/L primary standards for
each compound were made by adding a known amount of the neat chemical into
methanol in a 50-mL glass volumetric flask and then weighing the flask. A mixed
primary standard was made by adding 10 mL of the individual primary standards
to methanol in 100-mL flasks (200 mg/L) in the low-level study or 20 mL of
each individual primary standard (400 mg/L) in the high-level study. These
standards were kept in the freezer. On analysis days, working standards were
made by dilution of the mixed standard into deionized water. These standards
ranged in concentration from 2.0 to 0.2 mg/L in the low-level study and from 20
to 150 mg/L in the high-level study. For the field study the standards for TCE
were prepared in a similar fashion. Working standards in water ranged from 100
to 7.5 mg/L.
Metals
The items used in this study (e.g., high-density polyethylene [HDPE] sample
bottles, polypropylene (PP) Eppendorf pipet tips and volumetric flasks, etc.) were
acid-cleaned by soaking in a 10% solution (v/v) of nitric acid and deionized
water for several days, rinsing with deionized water, soaking in deionized water
for several more days, rinsing with deionized water, and air-drying. Samples
were collected in HDPE sample bottles (10 mL) and were acidified with concen-
trated (redistilled) nitric acid to a pH of less than 1 (acid concentration 2% v/v).
The chilled and acidified samples were sent in a cooler (with ice) by overnight
delivery to another of the Engineer Research and Development Center's labora-
tories, the Environmental Laboratory in Vicksburg, Mississippi, for analyses. The
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