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Currently, there exists no standardized method for the analysis of insensitive munitions (IM) in environmental matrices such as water, soils, and tissues. However, standardized methods for legacy munitions exist for water and soil matrices (i.e., United States Environmental Protection Agency [EPA] Method 8330B). The lack of standardized methods for IM analysis results in a wide variety of incomplete and overlapping analytical methodologies being modified from EPA Method 8330B for IM or use of methods developed for neat munitions compound analysis.
The overall project’s first phase was conducted under SERDP project ER-2722, with the objective to develop and optimize methods to address these methodological gaps by creating analytical methods for simultaneous analysis of IM and legacy munitions in water, soil and tissue matrices. Under ESTCP project ER19-5078, validation efforts built upon this previous work. The methods were validated and submitted to the EPA for inclusion as a possible addendum to EPA method 8330B. Lastly, these combined insensitive and legacy munitions methods have been published as a peer-reviewed journal article and the validation study results reported here will also be submitted for publication.
Project Summary
Inter-laboratory batch studies were used during method validation consisting of a series of round-robin studies with participating laboratories from the following:
Aqueous matrix studies were performed in three round robin formats (detailed in the Inter-laboratory Testing Methods section of the Final Report) separated by sample preparation technique: Round-robin 1 (direct injection), Round-robin 2 (solid phase extraction [SPE]), Round-robin 3 (low level SPE). The first aqueous round-robin study had eight participating laboratories, the second round-robin study had five participating laboratories, and the third round-robin study had four participating laboratories. Soil and tissue matrix round robin studies were conducted separately to ensure laboratories (three participants for soil matrices and four participants for tissues) had the ability to execute the number of samples generated. Soil and tissue round robin studies had three and four laboratories participating, respectively. Detailed methods developed through SERDP project ER-2722 were provided to participant laboratories alongside troubleshooting support and ample time to implement methods (six months minimum) on their specific instrumentation. ERDC-EL was responsible for preparing and distributing the samples in a “double-blind” manner, with sample pre-processing following EPA Method 8330B.
The round robin testing structure produced distinct groupings of data within each extraction method. The first was a synthetic group used to establish recovery ranges (in reagent water, American Society for Testing and Materials [ASTM] Fat Clay, or clean earthworm and ryegrass tissue) at a given tolerance interval. The first group was accompanied by spiked natural matrices (groundwater, surface water, and clean field collected soils) to assess whether natural matrices behaved similarly and recovered within the recovery ranges. The second group, an aqueous semi-synthetic group, was generated by diluting waters from Iowa Army Ammunition Plant (IAAAP) known to contain legacy and IM compounds. These IAAAP waters were fortified prior to dilution with the compounds that are included in ESTCP project ER19-5078, but weren’t detected in the waters. Lastly, a set of low-level samples were created by spiking reagent waters or ASTM Fat Clay to determine method performance near regulatory limits.
The calculated recovery ranges are generally wider than the control limits for EPA Method 8330B found in DoD QSM 5.4. However, the ranges are still within reason and likely reflect the increased difficulty in execution of these complex methods. The spiked natural matrices and the semi-synthetic results support this assessment and are also satisfactory, with infrequent issues occurring on a per-laboratory or per-analyte basis. Method performance degrades, as expected, as analytes are near instrument detection limits; however the calculated recoveries are broadly acceptable, albeit some analytes exhibit bias toward >100% recovery. A broad view of method performance, with laboratory data aggregated, reveals that the methods are effective, and that inter-laboratory variability is the main driver of varying analyte recoveries.
The validation of these methodologies is necessary to ensure that the techniques can be successfully implemented by other laboratories with varying instrumentation and analysts. Validation studies were used to assess method repeatability and reproducibility and are a requirement prior to their addition to EPA Method 8330B. These methods add the following benefits to EPA Method 8330B: (1) addition of 7 IM/IM degradation products, (2) addition of a surrogate (o-nitrobenzoic acid), (3) separate extraction procedures for soil and tissues, and (4) combined extraction and analysis of legacy and IM. These additions provide greater applicability and efficiency to monitoring efforts at firing ranges, demilitarization, and manufacturing facilities, and at any site where munitions are tested, manufactured, or detected. Analytical methods like these will also prove useful in environmental fate and transport studies requiring the analysis of both IM and legacy munitions.
Crouch, R.A, J.C. Smith, B.S. Stromer, C.T. Hubley, S. Beal, G.R. Lotufo, A.D. Butler, M.T. Wynter, A.L. Russell, J.G. Coleman, K.M. Wayne, J.L. Clausen, A.J. Bednar. 2020. Methods for Simultaneous Determination of Legacy and Insensitive Munition (IM) Constituents in Aqueous, Soil/Sediment, and Tissue Matrices. Talanta, 217:121008. doi.org/10.1016/j.talanta.2020.121008.
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, B.C. Giordano, M.T. Montgomery, A.J. Bednar. 2019. Development and Optimization of Extraction and Analytical Methods for Simultaneous Determination of IM and Legacy Explosive Compounds. U.S. Army Engineer Research and Development Center Technical Report, AD1084243.
Scircle, A., A. Kimble, J. Smith, B. Stromer, S. Beal, J. Clausen, T. Georgian, A. Mumford, G. Giarmo, M. Peterson, H. Hedgpeth, R. Crouch, and A. Bednar. 2023. Validation and Standardization of SPE and HPLC-UV Methods for Simultaneous Determination of Legacy and Insensitive Munitions. Environmental Nanotechnology, Monitoring and Management, 20:100837. doi.org/10.1016/j.enmm.2023.100837.