non, New Hampshire, or groundwater samples
schemes, but neutralization prior to analysis can
be performed if necessary.
from Vershire (PT), Hartland (TR), or Weathersfield
The second stabilization method selected for
(MW), Vermont. Groundwater samples were ob-
evaluation was addition of acetonitrile as a bio-
tained in duplicate from the Naval Surface War-
cide by itself or in combination with pH adjust-
fare Center in Crane, Indiana. One sample of each
ment to 3.5 with acetic acid. Miller et al. (1983)
duplicate was collected in a bottle containing so-
tested and recommended a variation of this
dium bisulfate such that the solution concentra-
method. Addition of acetonitrile is already a part
tion was 1.5 g/L. A second sample of each dupli-
of the salting-out solvent extraction method and
cate was collected without acidification.
hence disposal problems should not be increased.
This method would be less easily implemented in
Analyte spiking
the field, however, and the minimum concentra-
All analyte spiking solutions were prepared in
tion of acetonitrile required for effective preserva-
water. SARMs for each analyte were placed in in-
tion is not known.
dividual brown glass jugs, reagent-grade water
was added, and the contents were stirred continu-
ously at room temperature for a week. The solu-
tions were then filtered through 0.45-m nylon
EXPERIMENTAL MATERIALS
membranes into clean, brown glass jugs. No sol-
vents other than water were used in the prepara-
Chemicals
All standards and test solutions were prepared
tion of these solutions. The concentration of analyte
from Standard Analytical Reference Materials
in each aqueous spike solution was determined
(SARMs) obtained from the U.S. Army Environ-
against standards prepared in methanol or
mental Center, Aberdeen Proving Ground, Mary-
acetonitrile and diluted 1:1 with reagent-grade
land. Methanol used in preparation of analytical
water prior to analysis (EPA 1992).
standards and HPLC eluent was HPLC grade from
Baker. HPLC eluent was prepared by combining
equal volumes of methanol and water and vacuum
ANALYSIS
filtering through a 0.45-m nylon membrane to
degas and remove particulate matter. Acetonitrile
All water samples were analyzed by RP-HPLC
at either the U.S. Army Cold Regions Research
used in preparation of stock standards and as a
chemical preservative was HPLC-grade from
and Engineering Laboratory (CRREL) or the U.S.
Baker. Glacial acetic acid, used to acidify water
Army Engineer Waterways Experiment Station
(WES). At CRREL, analysis was conducted on a
samples, was reagent-grade from Baker. Sodium
modular system composed of a Spectra-Physics
Model SP8810 isocratic HPLC pump, a Spectra-
obtained from Aldrich. Humic acid, sodium salt,
Physics SP8490 UV variable-wavelength detector
was technical-grade from Aldrich.
set at 254 nm (cell path 1 cm), a Spectra-Physics
SP8875 autosampler equipped with a Rheodyne
Solid-phase extraction materials
Model 7010 Sample Loop Injector (100 L), a
Prepacked cartridges of Porapak RDX (Sep-Pak,
6 cc, 500 mg) were obtained from Waters Corpora-
Hewlett Packard 3376 digital integrator, and a
tion; they were precleaned by eluting with 15 mL
Linear strip-chart recorder. At WES, primary
analysis was conducted using a Waters Model
of acetonitrile followed by 30 mL of reagent-grade
600 system controller, Model 610 fluid unit,
water. Empore SDB extraction membranes (47 mm)
Model 717 plus Auto Injector set for a 50-L in-
were obtained from 3M Corporation; they were
jection, a 486 UV Variable Wavelength Detector
precleaned in the same manner as the Porapak
set at 245 nm, and a Maxima Chromatography
cartridges. Experimental Empore SDB-LS (extra
Work Station. Confirmation was conducted on
clean) membranes were used for samples from
a Waters LC Module 1 with a 486 UV Variable
the Naval Surface Warfare Center; they were
Wavelength Detector (245 nm), a 717 plus Auto
cleaned as described above.
Injector (50 L), and a Maxima 820 Chromatog-
raphy Work Station.
Water samples
Blank water samples were either reagent-grade
Depending on the specific test conducted, wa-
ter samples were either analyzed using the direct
water from a Milli-Q Type I water system, surface
method specified in SW846 Method 8330 (EPA
water from the Connecticut River in West Leba-
3
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