Highly sensitive splitless programmed temperature vaporizing (PTV)-large volume injection (LVI)-GC-MS-negative chemical ionization (NCI) method was developed and validated for the trace detection of explosives and related compounds from environmental matrices.

The human respiratory system is a highly complex matrix that exhales many volatile organic compounds (VOCs). Breath‐exhaled VOCs are often “unknowns” and possess low concentrations, which make their analysis, peak digging and data processing challenging. We report a new methodology, applied in a proof‐of‐concept experiment, for the detection of VOCs in breath. For this purpose, we developed and compared four complementary analysis methods based on solid‐phase microextraction and thermal desorption (TD) tubes with two GC–mass spectrometer (MS) methods. Using eight model compounds, we obtained an LOD range of 0.02–20 ng/ml. We found that in breath analysis, sampling the exhausted air from Tedlar bags is better when TD tubes are used, not only because of the preconcentration but also due to the stability of analytes in the TD tubes. Data processing (peak picking) was based on two data retrieval approaches with an in‐house script written for comparison and differentiation between two populations: sick and healthy. We found it best to use “raw” AMDIS deconvolution data (.ELU) rather than its NIST (.FIN) identification data for comparison between samples. A successful demonstration of this method was conducted in a pilot study (n = 21) that took place in a closed hospital ward (Covid‐19 ward) with the discovery of four potential markers. These preliminary findings, at the molecular level, demonstrate the capabilities of our method and can be applied in larger and more comprehensive experiments in the omics world.

The measurement of a temperature‐dependent volatilization rate of the nerve agent GB (sarin) from various common matrices, using a laboratory‐designed wind tunnel (model system), is described. Small GB droplets are dispersed on the matrices surfaces, and samples are collected from the model system and analyzed utilizing a solid phase extraction/gas chromatography analytical method. Profiles demonstrating the vapor concentrations as a function of time are calculated. The results indicate that asphalt blocks relatively conserve GB, exhibiting a slow‐release mode of action over at least 2 weeks. Nevertheless, using standard decontamination procedures such as super tropical bleach may prevent this secondary evaporation risk. The concentration profile of commercial sidewalk bricks show a moderate decay, probably due to the existence of basic sites in the cement‐containing bricks. Fast clearance of GB is measured from smooth surface tiles, as these porous tiles both adsorb and/or degrade GB droplets very quickly.

We developed and optimized surface-enhanced Raman spectrometry (SERS) methods for trace analysis of explosive vapour and particles using a hand-held Raman spectrometer in the field.

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