18 Dec 2024

The Effects of Physical Form, Moisture, Humic Acids, and Mixtures on the Photolysis of Insensitive Munitions Compounds

Abstract: The explosive formulations IMX-101 and IMX-104 are replacing conventional explosives in munitions, making them safer to transport and handle. However, munitions manufacturing and military training can lead to the environmental release of constituent insensitive munitions compounds. These IMCs absorb ultraviolet light and transform photochemically into products with potentially greater toxicity. This study explores the effects of physical form, moisture, humic acids, and compound mixtures on the photolysis of solid and dissolved IMCs under UV-A and UV-B light. Irradiation of dry vs. moist solid IMC crystals yielded few measured products, and while photolysis rates were not significantly different, they were orders of magnitude slower than for aqueous IMCs. There was no significant difference in photolysis rates for aqueous IMCs irradiated with 0, 0.4, and 4 mg L-1 humic acids, but 40 and 400 mg L-1 humic acids inhibited NTO and enhanced NQ photolysis. Although organic and inorganic products were detected in the mixtures, an average of 15–35 % of the theoretical starting IMC masses was not accounted for. Overall, aqueous IMCs transformed 4–48 times faster than the solid IMCs, but the environmentally-relevant conditions tested were found to play a minor role in IMC photolysis.

30 Jul 2020

PUBLICATION NOTICE: Environmental Analysis of Aqueous 3-Nitro-1,2,4-Triazol-5-One (NTO) by Ion Chromatography with Conductivity Detection

Abstract:  The newly fielded insensitive high-explosive compound 3-nitro-1,2,4-triazol-5-one (NTO) is mobile in the environment due to its high water solubility and low affinity for soils. The weak acidity of NTO (pKa 3.67) presents a challenge to environmental analysis by high-performance liquid chromatography but enables direct separation by ion chromatography (IC). Here we developed an IC method for NTO in natural water, soil, and postdetonation residue. A gradient potassium hydroxide separation effectively resolved the inorganic anions (F−, Cl−, NO2−, Br−, SO42−, NO3−, and PO43−) and NTO in 18 minutes. Suppressed conductivity of aqueous NTO was linear from 10 µg/L to 10 mg/L with a detection limit of 3 µg/L and quantitation limit of 9 µg/L. Recoveries of NTO-spiked natural water samples were 93%–118% at concentrations of 30, 100, and 500 µg/L. Recoveries of NTO-spiked soil samples were 91%–114% using deionized water (DI) extraction. NTO was completely recovered with DI-extraction in two postdetonation residue samples of IMX-101 but only partially recovered (58% and 69%) in two higher-concentration residues, potentially due to incomplete dissolution of the energetic particle matrix. These results support IC for confirmation analysis of environmental samples and for screening natural water samples while simultaneously analyzing inorganic ions.