Rapid Quantification of Ammonium Nitrate and Urea Nitrate Using Liquid Chromatography-High-Resolution Orbitrap Mass Spectrometry.

Resolution and sensitivity improvements in mass spectrometry technology have enabled renewed attempts at solving challenging analytical issues. One such issue involves the analysis of energetic ionic species. Energetic ionic species make up an important class of chemical materials, and a more robust and versatile analytical platform would provide tremendous value to the analytical community. Initial attempts at quantification of energetic ionic species employed high-resolution time-of-flight measurements with crown ether (CE) complexation and flow injection analysis (FIA). In this investigation, ammonium nitrate (AN) and urea nitrate (UN) in the presence of a crown ether complexation agent were explored by using high-resolution orbitrap mass spectrometry. Product ion scans of these signature complexes reveal positive identification of these energetic ionic species. Finally, quantification was demonstrated for both flow injection and liquid chromatography-mass spectrometry (LC-MS) analysis, suggesting the capability for routine and rapid analysis of these energetic ionic materials.

From the laboratory to the field: Chemical analysis of colored smoke pyrotechnic formulations via mass spectrometry techniques.

Smoke dyes are complex molecular systems that have the potential to form many molecular derivatives and fragments when deployed. The chemical analysis of smoke samples is challenging due to the adiabatic temperature of the pyrotechnic combustion and the molecular complexity of the physically dispersed reaction products. Presented here is the characterization of the reaction byproducts of a simulant Mk124 smoke signal on a multigram scale, which contain the dye disperse red 9 (1-(methylamino)anthraquinone), by ambient ionization mass spectrometry. Our previous work has examined the thermal decomposition of a simplified smoke system consisting of disperse red 9, potassium chlorate, and sucrose by anaerobic pyrolysis gas chromatography mass spectrometry performed at the laboratory milligram scale. The results from the lab scale test were compared with a fully functioned Mk124 in the field. To achieve this, Mk124 smokes were functioned in the presence of sampling swabs that collected byproduct residues from the smoke plume in the ambient environment. These swabs were then analyzed using ambient ionization mass spectrometry to identify the expended pyrotechnic residues, with particular interest in halogenated species. Previous work determined the toxicity of unforeseen byproducts identified on the laboratory scale, which were also detected in the field demonstrating the correlation of the laboratory testing to the fielded systems. By understanding the chemical composition of smokes and their reaction products, potential toxicity effects can be easily assessed, leading to safer formulations with improved performance. These results can help assess how smoke byproducts may impact Warfighter performance, personnel health, and the environment.

Detection and toxicity modeling of anthraquinone dyes and chlorinated side products from a colored smoke pyrotechnic reaction.

"Green" pyrotechnics seek to remove known environmental pollutants and health hazards from their formulations. This chemical engineering approach often focuses on maintaining performance effects upon replacement of objectionable ingredients, yet neglects the chemical products formed by the exothermic reaction. In this work, milligram quantities of a lab-scale pyrotechnic red smoke composition were functioned within a thermal probe for product identification by pyrolysis-gas chromatography-mass spectrometry. Thermally decomposed ingredients and new side product derivatives were identified at lower relative abundances to the intact organic dye (as the engineered sublimation product). Side products included chlorination of the organic dye donated by the chlorate oxidizer. Machine learning quantitative structure-activity relationship models computed impacts to health and environmental hazards. High to very high toxicities were predicted for inhalation, mutagenicity, developmental, and endocrine disruption for common military pyrotechnic dyes and their analogous chlorinated side products. These results underscore the need to revise objectives of "green" pyrotechnic engineering.