Simultaneous UHPLC/MS Analyses of Explosive Compounds

Significance of the Topic

Explosive residues pose environmental and security threats due to toxicity, carcinogenicity, and risk of water contamination. Rapid, selective detection in complex matrices is vital for compliance, forensic investigations, and hazard mitigation.

Study Objectives and Overview

This work aimed to develop an ultra-high performance liquid chromatography/mass spectrometry (UHPLC/MS) method capable of simultaneous separation, detection, and quantitation of four classes of explosive compounds (nitroaromatics, nitroamines, nitrate esters, and peroxides) in soil and standard samples.

Methodology and Sample Preparation

• Standard solutions spanning 0.01–20 mg/L were prepared in acetonitrile/water.
• Soil samples were spiked at 2–500 µg/kg, extracted with acetonitrile, sonicated, and concentrated.
• UHPLC separation using a Hypersil GOLD PFP (1.9 µm, 2.1 × 100 mm) column with a water/methanol gradient containing 1 mM ammonium formate.
• MS detection by APCI in positive/negative modes using selected ion monitoring (SIM) and full scan (50–400 amu).

Instrumentation Used

• Thermo Scientific Accela UHPLC system with pump and autosampler.
• Thermo Scientific MSQ Plus single‐quadrupole mass detector with APCI source.
• Hypersil GOLD PFP analytical column.

Main Results and Discussion

• Baseline separation of 17 analytes achieved within 13 minutes, including isomer pairs 2,4-/2,6-DNT and 4-A-2,6-/2-A-4,6-DNT.
• Calibration curves exhibited linearity over four orders of magnitude (correlation coefficients ≥0.997).
• LOQs and LODs reached ppb levels; TATP sensitivity improved 35-fold over previous LC/MS methods.
• Soil matrix recoveries exceeded 82% at 10 µg/kg and 94% at 500 µg/kg, with method LODs down to 0.2–0.6 µg/kg.
• Mass spectral library matching enhanced compound confirmation beyond retention-time based approaches.

Benefits and Practical Applications

This UHPLC/MS approach delivers fast, sensitive, and selective detection of a broad range of explosives, supporting environmental monitoring, forensic analysis, and homeland security operations. The method reduces analysis time and improves confirmation confidence.

Future Trends and Applications

• Integration of high‐resolution MS and automated data processing for real‐time field analysis.
• Miniaturization of instrumentation for on‐site screening.
• Expansion of spectral libraries to cover emerging novel explosives and degradation products.

Conclusion

The developed UHPLC/MS method offers a robust, high‐throughput solution for comprehensive explosive analysis in complex matrices, outperforming conventional approaches in selectivity, sensitivity, and throughput.

References

• D.R. Felt et al., Talanta, 76 (2008) 21–28.
• R. Tachon et al., J. Chromatogr. A (2007), doi:10.1016/j.chroma.2007.03.059.
• Agilent Application: Analysis of Trace Residues of Explosive Materials by TOF LC/MS.
• A. Gapeev et al., Rapid Commun. Mass Spectrum. 17 (2003) 943–948.