On-site Screening of Explosive Materials by Portable SPME-GC/MS and CME-GC/MS

Significance of On-site Screening of Explosive Materials

Detecting homemade explosives and improvised explosive devices rapidly and accurately at or near the point of threat is essential for security forces and first responders. The chemical complexity of modern threats, including primary energetic compounds, stabilizers, propellants and tagging agents, requires versatile field-ready analytical techniques. Portable gas chromatography–mass spectrometry (GC/MS) combined with solid phase microextraction (SPME) and coiled microextraction (CME) offers a broadly applicable approach to screen for both volatile and semi-volatile components of explosive formulations.

Objectives and Study Overview

This study demonstrates the field application of Custodion SPME and CME sampling devices paired with the Torion T-9 portable GC/MS system for on-site detection and identification of explosive materials and associated chemical markers. Specific goals include establishing sampling protocols for a range of pure explosive compounds, metabolites, stabilizers, propellants and tagging agents, and assessing the capability of each extraction technique in realistic screening scenarios.

Methodology and Used Instrumentation

All analyses were performed using a PerkinElmer Torion T-9 portable GC/MS, with data processing and deconvolution in Chromion PC software. Reference materials at 1000 and 100 µg/mL were prepared in headspace vials for SPME sampling and in methanolic solutions for CME. Key parameters:

• SPME fiber: DVB/PDMS 65 µm; headspace exposure at 37 °C (or 70 °C) for 5 min
• CME wire: direct immersion for ~5 s, drying for 60 s
• GC column: MXT-5, 5 m × 0.1 mm, 0.4 µm film; temperature ramp 40–280 °C at 2 °C/s, hold 60 s
• Injector: splitless at 175 °C; transfer line 175 °C; helium carrier gas 0.2 mL/min
• MS: in-trap electron impact ionization, toroidal ion trap analyzer, mass range 41–500 Da

Results and Discussion

Combination of SPME and CME sampling extended detection to a broad chemical space:

• Volatile stabilizers, tagging agents and propellants were reliably detected by SPME within 5 min, enabling rapid initial screening.
• Six of twelve primary explosives yielded sufficient signal by SPME; remaining high-boiling explosives required CME liquid injection for robust detection.
• CME sampling produced a 400-fold signal increase for TNT over SPME, highlighting its advantage for semi-volatile compounds.
• Direct immersion CME of methanolic soil extracts enabled identification of TNT metabolites (e.g. 1,3,5-trinitrobenzene, amino-dinitrotoluenes).
• Tagging agents such as EGDN and DMNB were readily profiled by headspace SPME, supporting canine and instrument detection strategies.

Practical Benefits and Applications

This workflow supports rapid on-site decision making, offering:

• Minimal sample preparation and fast analysis times
• Detection of both primary explosives and secondary chemical markers
• Portability for checkpoints, field investigations and environmental monitoring
• Data-driven risk assessment to prioritize safety measures

Future Trends and Opportunities

Advances likely to enhance field screening include integration of ion mobility or alternative ionization sources, expansion of miniaturized GC/MS systems, automated spectral matching with machine learning, and remote real-time data sharing. Application of these techniques to other threat classes, such as narcotics or chemical warfare agents, will broaden the utility of portable SPME/CME-GC/MS platforms.

Conclusion

The combined use of Custodion SPME and CME sampling with the Torion T-9 portable GC/MS delivers comprehensive on-site screening capability for explosive materials and related chemical indicators. This approach balances speed, sensitivity and versatility, empowering security personnel to assess and mitigate explosive threats in diverse operational environments.

References

1. Vogelsanger, B. Chemical Stability, Compatibility and Shelf Life of Explosives. Chimia 2004, 58 (6), 401–408.
2. Heinlein, T. Rapid Field Identification of Explosives, Tagging Agents and Metabolites by the Portable Torion T-9; 2017.
3. Heinlein, T. Determination of Explosive Compounds in Soil Samples Using the Torion T-9 GC/MS with SPME sampling. 2017.