Fast and Direct Detection of Explosives using SICRIT®-MS

Significance of the topic

Rapid and reliable detection of explosives is essential for homeland security, counter-terrorism and critical-infrastructure protection. Conventional approaches often rely on chromatographic separation or canine sniffers, which can be time-consuming or resource-intensive. A soft ionization method that enables direct mass spectrometric analysis of trace levels of explosive compounds promises faster, more versatile screening both in the laboratory and in the field.

Objectives and overview of the study

This application note explores the suitability of the SICRIT® soft ionization source for direct mass spectrometric detection of seven relevant explosives. The study aims to demonstrate the ionization efficiency, selectivity and potential integration of SICRIT® with existing LC-MS platforms for rapid explosive screening.

Methodology and instrumentation

The experiment employed a 3 ppm mixture of Tetryl, TNT, FOX-7, PETN, HMX, RDX and TATP (3 ng each). A 1 µL aliquot was injected into the SICRIT® GC/SPME module (200 °C) using a PAL3 RTC autosampler. The carrier gas was humidified nitrogen. Ionization was performed at 1.5 kV/15 kHz. Mass analysis was carried out on a Thermo Fisher LTQ Orbitrap XL in full-scan mode (50–500 m/z, 30 000 FWHM), operating in negative-ion mode for nitro-based explosives and positive-ion mode for TATP.

Main results and discussion

All seven explosives produced clear, characteristic signals under soft-ionization conditions:

• Tetryl yielded a dominant [M-NO2]– ion at m/z 241.0210.
• TNT showed both [M-H]– at m/z 226.0099 and a secondary [M-NO]– at m/z 197.0198.
• FOX-7, PETN, HMX and RDX predominantly formed [M+NO3]– adducts at their respective masses (m/z 210.0112, 377.9999, 358.0238 and 284.0225).
• TATP was effectively detected in positive mode as an [M+NH4]+ adduct at m/z 240.1432.

The full-scan spectra confirm the soft-ionization nature of SICRIT®, preserving molecular information for unambiguous identification.

Benefits and practical applications

• Direct analysis without chromatographic separation accelerates throughput.
• Ambient sampling (“sniffing”) capability allows in situ screening of air, surfaces or swabs.
• Plug-and-play integration with any LC-MS system facilitates adoption in existing laboratories.
• No need for consumable gases supports continuous, mobile or remote operation.

Future trends and possibilities

Further studies should address detection limits, quantitation and matrix effects in realistic scenarios. Miniaturized MS platforms combined with SICRIT® could enable handheld explosive sensors. Integration into walk-through portals, cargo scanning systems or unmanned aerial vehicles offers potential for automated, real-time security screening.

Conclusion

The SICRIT® soft ionization source delivers efficient, gentle ionization of key explosive compounds, generating informative mass spectra without chromatographic steps. These promising results support its use for rapid, on-site explosive detection and point to new MS-based sensor solutions in security and defense applications.