Metal-Ion Catalyzed Alcoholysis Based Disclosure Solution for the Detection of CW Nerve Agents on Sensitive Materials for Spray and Wipe-Based Applications
Chemical warfare agents (CWA) are defined by the Chemical Weapons Convention as "any chemical which, through its chemical effect on living processes, may cause death, temporary loss of performance, or permanent injury to people and animals." Chemical warfare agents, such as the nerve agents and vesicants still pose a threat to global security and western interests. State and non-state actors continue to develop, stockpile, and weaponize these agents due to their mass effect on life, their ability to deny territory, and the ability to cause social and psychological distress. Since World War 1, CWA detection methodologies have been researched and implemented. They permit security forces and first responders to obtain early warning and adopt force protective measures. Briefly summarized is the chemistry of past and in-service chromogenic CWA detection systems, followed by a literature review of chromogenic and fluorogenic chemical-based detection methodologies currently being researched for nerve agents and vesicants. It is concluded that presently there is no suitable universal disclosure system or approach which can undergo an immediate, sensitive, and practical chromogenic response in the presence of CW nerve agents; phosphonofluoridates, phosphonocyanidates, and phosphonothioates. As a result, a novel and practical strategy is proposed and developed which combine La(III) metal-ion catalyzed alcoholysis (MICA) and chromogenic sensors. Since the strategy utilizes alcohol at neutral conditions, it can be employed to disclose CWA on sensitive materials. Three novel strategies are investigated for the detection of the phosphonofluoridates, two of which detect for F- produced via MICA. First, the cleavage of silylated ethers with a chromophoric core, and second, a displacement mechanism where F- interacts with La(III) resulting in the displacement of a metal-associated chromophoric sensor into solution. The third strategy focuses on the production and detection of H+, another product of MICA. The detection of phosphonocyanidates is adapted to this H+ strategy by the addition of a borderline M(II) that associates with the –CN product. Furthermore, a compatible sensor, 83, based on thiol-disulfide interchange, is developed and investigated for the detection of phosphonothioates. Finally, the sensors and methodologies are integrated into a stable universal solution, and its effectiveness demonstrated.