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METHOD DEVELOPMENT FOR THE DETERMINATION OF HEXAHYDRO-1,3,5-TRINITRO-1,3,5-TRIAZINE (RDX) IN DRINKING WATER
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.
RDX is an explosive that is commonly found in and around military installations. RDX can contaminate groundwater, creating the potential for it to occur in drinking water. RDX was listed as a contaminant on the 1998 Contaminant Candidate List (CCL). The CCL lists potential drinking water contaminants that EPA is evaluating for possible regulation under the Safe Drinking Water Act. In order to make a regulatory determination on RDX, EPA must have reliable nationwide occurrence data for RDX in drinking water. Under this task, one or more analytical methods will be developed for the determination of RDX in drinking water. The method(s) will be used by the Office of Ground Water and Drinking Water to gather occurrence data for RDX under its Unregulated Contaminant Monitoring Rule (UCMR). The occurrence data obtained will support EPA's regulatory determination process. The lifetime health advisory concentration for RDX in drinking water is 2 Fg/L. In addition, there is some indication that RDX may be a carcinogen, with an estimated lifetime cancer risk of 1 in 100,000 associated with a drinking water concentration of 3 Fg/L.
Current literature references indicate that immunoassay and biosensor techniques as well as gas chromatography (GC) and high performance liquid chromatography (HPLC) have been used in analytical methods to measure RDX in ground water matrices. Immunoassay techniques are relatively insensitive and subject to false positive results due to cross reactivity with chemicals similar in structure to RDX. These characteristics make these methods unsuitable for UCMR monitoring. Existing GC and HPLC methods require two chromatographic columns to separate and measure common explosive contaminants, and they use non-specific detectors which increases the potential for false positive results. A method based on solid phase extraction followed by GC/MS analysis will be the initial approach for this project, because this approach is expected to provide the sensitivity and selectivity needed for occurrence monitoring. A final method will be delivered to OGWDW by Sept. 2002.