Simultaneous UHPLC–MS Analyses of Explosive Compounds

Explosive compounds are widely used in warfare, mining industries, terrorist attacks, and civil constructions. Explosive contaminated soils are mostly found on firing points, impact areas, and training ranges. The explosive contaminates in soil are possible sources for surface and ground water contaminations, posing environmental and public health risks due to the compounds' toxicity, carcinogenicity, and mutagenicity.

Instrumentation

An ultra high performance liquid chromatography-mass spectrometry (UHPLC–MS) method was developed to efficiently separate, detect, and quantitate all four classes of explosive compounds, including eight nitroaromatics, two nitroamines, five nitrate esters and two peroxides. The explosives were separated on a Hypersil GOLD PFP 1.9 μm, 2.1 × 100 mm column and detected by selected ion monitoring (SIM) on an MSQ Plus Mass Detector — a fast scanning, single-quadrupole mass spectrometer.

Results

The simultaneous separation and detection of 17 explosive compounds was achieved through UHPLC–MS, using the Thermo Scientific Accela system with a fast scanning, single quadrupole mass spectrometer (Figure 1). The sensitivities were achieved at ppb level for TNB, 1,3-DNB, TNT, 2,6-DNT, 2,4-DNT, TATP, and TETRYL. This represents a 35 times improvement in the detection sensitivity for TATP relative to the detection sensitivity of the Agilent instrument and method. The detection sensitivities obtained by the UHPLC–MS method with library matching of APCI mass spectra was more than 10-fold versus the EPA 8330 method.

Figure 1

Conclusions

The simultaneous analyses of nitroamines, nitroaromatics, nitrate esters, and peroxide explosives by UHPLC-MS were accomplished utilizing sub-2-μm particles, improved the separation efficiencies and resolutions. The MS detection method offered improved sensitivities, good selectivity, and additional MS confirmations. The detection sensitivities were further increased by the preconcentration step implemented in the sample preparation process. The more confirmative identifications of explosives were achieved by comparing all of the collected APCI mass spectra to the comprehensive MS spectra library of the explosive residues. Improved separation performance, increased detection sensitivity, and better selectivity were demonstrated, compared to the current USEPA 8330 method with 35 times detection sensitivity for TATP compared to the alternative instruments and methods (1).

Reference

(1) Agilent Application: Analysis of Trace Residues of Explosive Materials by Time-of-Flight LC–MS.

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