No standard method currently exists for analyzing insensitive munitions (IM) compounds in environmental matrices (with or without concurrent legacy compounds). Lacking established methods, contract and research laboratories either do not measure IM compounds at all; quantify some but not all, using US Environmental Protection Agency (USEPA) Method 8330B developed for legacy compounds (leading to inaccuracies for certain IM compounds and degradation products [Felt et al., 2016]); or, use methods originally developed for neat materials with no proven performance metrics. The primary objective of this project was to develop new methods of extraction, pre-concentration, and analytical separation/quantitation of 17 legacy and seven IM compounds, daughter products of IM, and other munitions compounds absent from USEPA Method 8330B. The final product is a single standardized method for simultaneous analysis in environmental matrices, leading to cost savings with minimal increase in environmental monitoring and no change to existing sample collection procedures.
Currently accepted methods of analysis (high-performance liquid chromatography [HPLC], micellar electrokinetic chromatography [MEKC], capillary electrophoresis [CE] and extraction [solid phase extraction and solvent extraction]) were modified for applicability to the proposed list of 24 analytes. New methods of extraction, pre-concentration, and analytical separation/quantitation of the proposed list were developed for simultaneous analysis of legacy and IM compounds in environmental matrices. The methods were verified in laboratory-spiked water, soil, and tissue samples. Stability studies were performed to investigate applicability of current extraction and analysis hold times. Inter-laboratory studies were performed using batch-spiked water and soil samples to investigate extraction and analytical method transfer from the originating laboratory.
Two HPLC separation methods with ultra violet detection were developed that allow the detection and quantitation of 24 legacy and IM compounds (plus two surrogates), with μg/L detection limits. A liquid chromatography–mass spectrometry method was developed as an alternate confirmatory analysis. Alternate analytical methods using MEKC and CE were developed to detect compounds of interest present at higher concentrations. Extraction methods for water and solid matrices were developed by modification of existing USEPA Method 8330B and previously developed U.S. Army Engineer Research and Development Center methods. The developed solid phase extraction method was tested on five water sources, including river, sea, and ground water, with a majority of compounds recovered within current Department of Defense quality systems manual (QSM) Version 5.2 limits. A 2-step solvent extraction method was developed for soils, which included testing of five field soils. Recoveries of all 24 compounds of interest (and two surrogates) for all soils were within QSM limits. A single 18-h solvent extraction method was developed for tissues, including a soil-dwelling invertebrate, freshwater vertebrate, marine invertebrate, and perennial plant. In order to address observed analytical interferences, a post-extraction preparative chromatographic method was developed, which allowed for improved recoveries of several compounds in tissues, including nitroguanidine and 5-nitro-1,2-dihydro-1,2,4-triazol-3-one. A majority of compounds were recovered within QSM limits, with generally low recovery only for tetryl.
The development of methods to simultaneously analyze legacy and IM compounds is necessary to enable monitoring of each component at firing ranges, demilitarization and manufacturing facilities, and environmental sites, where munitions compounds are tested, produced, and detected (Felt et al., 2013; Walsh et al., 2014). New methods for extraction and analysis of the legacy and IM compounds of interest were developed. New HPLC methods reduce total analytical run time by approximately 25% versus the use of separate legacy and IM methods. Simultaneous extraction and preparation of one rather than two sets of analytical samples could reduce labor and supply costs by 50%. Products of this work will assist in conducting fate and transport studies for IM compounds by providing a standardized method for quantitation of concurrent IM and legacy materials. This is needed to determine long-term environmental impacts.
Crouch, R. A., J. C. Smith, B. S. Stromer, C. T. Hubley, S. Beal, G. R. Lotufo, A. D. Butler, M. T. Wynter, D. A. Rosado, A. L. Russell, J. G. Coleman, K. M. Wayne, J. L. Clausen, and A. J. Bednar. 2020. Development and Optimization of Extraction and Analytical Methods for Simultaneous Determination of IM and Legacy Explosive Compounds. Talanta, 217:121008. .
Crouch, R. A., J. C. Smith, B. S. Stromer, C. T. Hubley, S. Beal, G. R. Lotufo, A. D. Butler, M. T. Wynter, D. A. Rosado, A. L. Russell, J. G. Coleman, J. L. Clausen, and A. J. Bednar. 2021. Development and Optimization of Extraction and Analytical Methods for Simultaneous Determination of IM and Legacy Explosive Compounds. US Army Corps of Engineers, Engineer Research and Development Center, Environmental Laboratory, ERDC TR-21-12. http://dx.doi.org/10.21079/11681/41480.