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10
ERDC/CRREL TR-02-1
3
SAMPLE PRESERVATION, EXTRACTION, AND
ANALYSIS
To obtain reliable analytical results for soil and water samples contaminated
with explosives, the pre-extraction maximum holding time (MHT) for a specific
set of conditions, listed in Appendix E, should be observed. Because EM-
contaminated sites may contain many types of energetic compounds, the methods
and techniques used in the extraction and analysis of samples must be robust.
Numerous studies have addressed the optimization of the extraction of explosives
from soil and water matrices (Jenkins et al. 1986, Bauer et al. 1986, Liquid
Chromatographic Method 1986, Jenkins and Grant 1987, Army Environmental
Sciences 1989). The accepted soil extraction procedure is the EPA 8330 sonica-
tion method that is covered in Appendix F. Aqueous samples require an initial
preconcentration step before analysis to transfer the explosives into the appro-
priate solvent and to enable measurement in the low parts-per-billions (g/L)
range. Two methods are available for groundwater extraction: the salting-out
method that can be found in Appendix F and the solid-phase cartridge extraction
(SPE) method that is described in Appendix G. In the past, the preconcentration
method of choice was the salting-out technique; more recently, the SPE
technique (Appendix G) is preferred because of its speed, reproducibility, and
ease of use.
For precise determination of the analytes in a wide range of matrices, U.S.
EPA Method 8330 is preferred (Grant et al. 1993a, b; Appendix F). When ana-
lyzing samples suspected of being contaminated with trace levels of EM in both
soil and water matrices, gas chromatography coupled with an electron capture
detector (GC-ECD, U.S. EPA Method 8095, Appendix F) provides greater
sensitivity than Method 8330 (Walsh and Ranney 1998, 1999). Detection limits
for Method 8095 are typically two to three orders of magnitude lower than
Method 8330 for comparable sample extracts (Table 2). Furthermore, Method
8095 is applicable to all of the analytes covered by Method 8330 along with NG,
PETN, and 3,5-dinitroaniline (3,5-DNA).
Field Screening Methods
Field analytical chemistry (FAC) is a rapidly growing application that allows
sample analysis to be performed on site. Traditionally, sample analysis has been
undertaken at a remote site, therefore requiring sample transportation and storage
prior to analysis. These additional steps represent important delays because days
and often weeks elapse before information on the identity and quantities of
chemicals in the sample become available, deferring the ability to make vital
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