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METHOD 529, DETERMINATION OF EXPLOSIVES AND RELATED COMPOUNDS IN DRINKING WATER BY SOLID PHASE EXTRACTION AND CAPILLARY COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY
Munch, J W. METHOD 529, DETERMINATION OF EXPLOSIVES AND RELATED COMPOUNDS IN DRINKING WATER BY SOLID PHASE EXTRACTION AND CAPILLARY COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY. U.S. Environmental Protection Agency, Washington, DC, 2005.
To develop an analytical method for monitoring RDX and other explosives in drinking water, which will be suitable for use by OGWDW to collect nationwide occurrence data under the UCMR. Ideally, the method should be simple and rugged enough to be applicable to compliance monitoring in the event that RDX becomes a regulated contaminant under the Safe Drinking Water Act (SDWA). The method should be sensitive enough to provide accurate and precise data below 2 Fg/L.
Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a military explosive which is known to have contaminated groundwater on and near military installations where it has been used and stored. Historical disposal practices such as open burning and detonation have contributed to environmental contamination. EPA has classified RDX as a possible human carcinogen, and has established a Lifetime Health Advisory of 2 g/L. The project focus was to develop a sensitive and specific analytical method for the analysis of RDX in drinking water. Existing analytical methods for measuring RDX are sensitive but not very specific. The need for this project arose from the 1998 Contaminant Candidate List (CCL) which was developed in response to the 1996 amendments to the Safe Drinking Water Act. The CCL, published by EPA'S Office of Ground Water and Drinking Water, identifies potential drinking water contaminants that might be regulated by EPA at some future date. RDX was identified as a CCL chemical on the 1998 list. The analytical method developed will be proposed for the collection of nationwide occurrence data for RDX, and possibly other explosives and related chemicals, in the next Unregulated Contaminant Monitoring Rule (UCMR) scheduled for 2004. In the event that a decision is made to regulate RDX in drinking water, the method could also be used for compliance monitoring.
Approach The research goal was to develop a method for measuring RDX and up to 16 additional explosives, degradation products, and manufacturing by-products. The initial method detection limit goal for RDX was 0.5 g/L, well below the Lifetime Health Advisory of 2 g/L. As the project progressed, new health information indicated that additional sensitivity may be necessary. The approach involved developing procedures for (1) sample collection, preservation, shipping and handling, (2) extraction and concentration of the target analytes from an aqueous solution, (3) separation of the analytes chromatographically, and (4) detection and quantification. Solid phase extraction techniques were investigated for the extraction of explosives and related compounds from aqueous samples. Gas chromatography/mass spectrometry (GC/MS) was investigated for the chromatographic separation and detection steps, because of its specificity.
Results and Implications
The analytical method developed from this research can be used to measure RDX and 13 additional explosives and related chemicals in drinking water samples. The method detection limit for RDX ranges from 0.006 - 0.12 g/L depending upon the various options selected within the method protocol. The most sensitive procedure employs Selected Ion Monitoring (SIM) GC/MS. These concentrations are expected to be below those needed for drinking water monitoring, based upon currently available health effects information. This method is an improvement over other published methods for RDX in the following ways: (1) use of the mass spectrometer as the detector provides positive identification of all method analytes without the use of additional confirmatory techniques, and (2) the sample preservation protocol ensures sample stability between the time of sample collection and analysis. These improvements will significantly enhance the use of this methodology in the collection of nationwide occurrence data to support regulatory decision making for chemicals on the CCL.
This research project directly supports ORD's research under the Government Performance and Results Act (GPRA) Goal 2- Clean and Safe Water, Objective 2 - Ensure Safe Drinking Water and Recreational Waters, Sub-objective 7 - Safe Drinking Water Act Research. The results of this project address GPRA annual performance goal (APG) 27 ["Produce scientific reports on unregulated drinking water contaminants, in support of the development of the next list of chemicals and pathogens for potential regulatory action (i.e., Contaminant Candidate List #2). These reports will help ensure that future drinking water regulations address the contaminants of greatest public health concern."], and annual performance measure (APM) 78 ["Improved methods for CCL related chemicals in drinking water for use in the Unregulated Contaminant Monitoring Rule"].