SPME GC-TOFMS of Smokeless Powders

Significance of the topic

Smokeless powders are widely used propellant materials in ammunition, and their volatile components provide critical information for forensic investigations and quality control. Profiling these volatiles allows analysts to differentiate powder formulations, trace sources, and ensure product consistency.

Aims and study overview

This application snapshot evaluates the use of solid-phase microextraction (SPME) coupled with gas chromatography–time-of-flight mass spectrometry (GC-TOFMS) to characterize the volatile organic compounds emitted by two smokeless powder formulations (Powder A and Powder B). The goal is to demonstrate a rapid, solvent-free approach for comprehensive profiling of nitrate esters, stabilizers, and nitroaromatic additives.

Methodology

Samples of each powder were heated to 90 °C in a vial, and headspace volatiles were collected using a 50/30 µm DVB/Car/PDMS SPME fiber. After equilibration, the fiber was desorbed in the GC inlet.

Instrumentation used

• Gas chromatograph fitted with a 20 m × 0.25 mm × 0.71 µm RTx-TNT capillary column.
• LECO Pegasus GC-TOFMS system operating at 10 spectra/s across m/z 45–550.
• 50/30 µm DVB/Car/PDMS SPME fiber for headspace sampling.

Main results and discussion

TIC chromatograms for Powder A revealed dominant peaks corresponding to nitroglycerin, diphenylamine, p-nitrodiphenylamine, and dinitrotoluene. Powder B showed a distinct profile with relative intensities shifted among these compounds. The high resolution and mass accuracy of TOFMS enabled clear identification of isobaric species. Comparative analysis highlights differences in stabilizer and aromatic content between formulations.

Benefits and practical applications

• Rapid, solvent-free sampling reduces preparation time and environmental impact.
• Comprehensive detection of nitrate esters and nitroaromatic stabilizers enhances forensic differentiation of powder sources.
• High spectral acquisition rates ensure accurate deconvolution of coeluting compounds.
• Suitable for QA/QC in ammunition manufacturing to monitor consistency and detect impurities.

Future trends and applications

Advancements may include automated SPME-GC-TOFMS workflows with robotic sampling, machine learning algorithms for pattern recognition, and miniaturized portable TOFMS systems for field deployment. Development of novel fiber coatings could expand the range of detectable low-volatility compounds.

Conclusion

The combination of SPME headspace sampling with GC-TOFMS offers a powerful, efficient platform for profiling volatile constituents of smokeless powders. This approach supports forensic investigations, quality assurance, and research into new propellant formulations.