the HPLC method. The same method was used at CRREL for the statistical evaluation
of the energetics in Shaver River Range. The HPLC method was preferred over the
Gas Chromatography method recently published since reproducible results with the
GC/ECD Method were difficult to achieve [22-23]. In our study, the HPLC method
gave us a detection limit of 0.25 ppm for all analytes and this detection limit was
reduced to 0.06 ppm when the sample extracts were concentrated in a Zymark
apparatus.
Soil samples were dried in the dark, homogenized by adding acetone to form a slurry
which was then evaporated. Soils were sieved through 25-mesh sieves and extracted
at DRDC Valcartier according to the following procedure. Eight grams of soil were
put into an amber glass vial and mixed with acetonitrile (10 mL). A vortex was
applied for one minute, followed by a sonication period of 18 hours in an ultrasonic
bath in the dark. The samples were left to settle for 30 minutes. Acetonitrile (2 ml)
was decanted from the vial and diluted with water (2 ml) containing calcium chloride
(1%). The solution was filtered on a 0.45 microns filter to get 1 ml of solution ready
to inject into the HPLC.
Soil extracts were maintained at 4C until analyzed by HPLC according to Method
EPA 8330 update SW 846 (1994). Analyses were performed with a HPLC Agilent HP
1100 equipped with a degasser G1322A, a quaternary pump model G1311A, an
autosampler G1313A and a UV diode array detector model G1315A monitoring at
210, 220 and 254 nm. The injection volume was 20 l and the column was a
Supelcosil LC-8 (25 cm x 3 mm x 5 m) eluted with 15:85 isopropanol/water (v/v) at
a flow rate of 0.75 ml/min. The column temperature was maintained at 25o C during
the analysis. Standards and solvents were diluted 1:2, acetonitrile to water (0.5 ml
Acn /0.5 ml water). When 8 g in 10 ml of acetonitrile were used for the soil
extraction, the detection limit for this method was 0.25 ppm.
In order to obtain lower detection limit ( 0.062 ppm), we concentrated to dryness 2 ml
of acetonitrile from the soil extract with a Zymark evaporator (model TurboVap LV)
in a test-tube. Thereafter, we added 0.5 ml of water and 0.5 ml of acetonitrile and
used this mixture as the extract to inject for the analysis.
The reporting limits obtained for energetic materials in the present study were
typically between 100 to 1000 ppb for soils depending on the analyte. No vegetation
samples were analysed for energetic materials, since no explosives were detected in
another studies [27-28].
For the analyses of the samples collected for the statistical evaluation performed in
Shaver River Range, CRREL used the same HPLC analytical method, but with some
small variations in their protocol. Below is a description of the method used by
CRREL for their analyses of explosives in the discrete samples and the composite
samples collected in front of the Shaver River Range target.
Soil samples were air dried at room temperature. The discrete and composite samples
were processed differently because the sample masses were quite different. Discrete
samples weighed from 48 to 109 grams, while the composite samples weighed over
one kilogram. Discrete samples were dried in the 4-oz amber containers, passed
through a #10 (2-mm) sieve to remove oversize material, and returned to the 4-oz
5
DRDC Valcartier TR 2004-204
Previous Page
