Earth’s Field NMR for Organophosphate Chemical Warfare Agent Detection

Organophosphorus (OP) nerve agents are a group of lethal small molecules. Fieldable detection of nerve agents is an on-going challenge that typically relies on mass spectrometry and infrared spectroscopy but not nuclear magnetic resonance (NMR) spectroscopy because of the portability limitations of superconducting magnets. However, Earth’s field NMR (EFNMR) demonstrates a unique signature space for OP compounds and can be made into a portable detector for OP nerve agents. Here we demonstrate a systematic study to develop the EFNMR signature space of 31 nerve-agent-related OP compounds, including surrogates, simulants, synthetic precursors, decomposition products, pesticides, and threat agents identified by the National Institutes of Health. The EFNMR spectral signatures are a diagnostic fingerprint of the molecular structure, and this study establishes the structure–signature relationships of this relatively unexplored signature space. The results indicate that EFNMR is a powerful analytical capability to distinguish and identify the unique structure of OP compounds, including nerve agents. While aimed at detection of nerve agents, this study also lays the foundations of using EFNMR for detection of any OP compound in the laboratory or in the field.