Detection of Explosives using a Portable SPME/GC-Cylindrical Ion Trap Mass Spectrometer

Amber L. Russell1, Anthony J. Bednar2, Denise K MacMillan3, Charolett A. Hayes1, Beth Porter1, Nate D. Nulherin4, and Louise Parker4

1SpecPro, 3532 Manor Dr. Vicksburg, MS 39180, 2Engineer Research and Development Center, 3909 Halls Ferry Rd, Vicksburg, MS 39180, 3Environmental Protection Agency, 109 TW Alexander Drive, RTP, NC 27711

4Cold Regions Research and Engineering Laboratory, 72 Lyme Rd, Hanover, NH 03755

INTRODUCTION:

Long term monitoring at Department of Defense sites is required to demonstrate successful remediation and regulatory compliance. The monitoring programs are expensive with the majority of the costs related to sampling, shipping, and analysis. Field analytical technologies can reduce monitoring costs compared to fixed laboratories, however the field instruments must produce data that are acceptable for regulatory purposes. The goal of this work is to test a field analytical method for munitions constituents found in ground water at a formerly used Department of Defense site.

RESULTS & DISCUSSION:

A Griffin Analytical Technologies Minotaur 300 cylindrical ion trap (CIT) was used to develop an analytical method for the detection of munitions constituents. The munitions constituentsof interest were TNB, RDX, 1,3-DNB, TNT and 2,4-DNT, all known contaminants of the field site. Concentrations of the munitions constituents in the ground water of the site ranged from ~40 ppb to 16 ppm.

CONCLUSION:

The results of this work demonstrate a successful field analytical technology for the detection of munitions constituents in groundwater. We are currently investigating other techniques for improved detection of RDX and HMX.

PROCEDURE:

Standard low flow sampling was used to collect water from monitoring wells at the site (Figure 1). Samples were extracted with SPME fibers and analyzed immediately on the Minotaur 400. The method developed on the Minotaur 300 was transferred to the field ruggedized Griffin Analytical Technologies Minotaur 400 mass spectrometer for the field work. Additionally 500 mL samples were transported to our fixed laboratory for analysis by the traditional method for explosives, SW-846 EPA Method 8330.

The CIT was equipped with a Restek RTX-TNT heated gas chromatography capillary column, which allowed for confident identification of the target analytes and separation from interferences. Target analytes were identified by comparison to the retention times and mass spectra of known standards. Solid phase micro-extraction (SPME) fibers were chosen to eliminate chemical waste generated in the field and reduce sample volumes.

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The results from the samples that were extracted and analyzed immediately in the field show better detection of the low level constituents, compared to SPME fibers collected in the field and run later in the lab (Figures 3 & 4). The traditional EPA method for explosives was able to identify more compounds of interest than the GC-MS SPE results from on the Minotaur 400. We are able to detect RDX but not HMX using direct injection followed by analysis using the Minotaur 400 GC-MS. RDX was not detected from the SPE extractions of the well water. HMX is also a known contaminant of the site.

Figure 1: Sampling well water at a formally used DOD site

Figure 2: Griffin Analytical Technologies Minotaur 400 Mass Spectrometer

Figure 3: Results from GC-MS and HPLC Analysis of well water

Figure 4: Chromatograms from GC-MS analysis of well 104

TNTTNB1,3-DNB1,4-DNT

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TNTTNB1,4-DNT

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TNT

TNBMystery Peak