Degradation of the chemical warfare agents HD, GD, thickened GD, and VX on ambient and moist environmental substrates

Abstract

The rates, products, and mechanisms of the degradation of the chemical warfare agents GD, thickened GD, HD and VX on environmental substrates were determined using Solid State Magic Angle Spinning Nuclear Magnetic Resonance (SSMAS NMR). Increases in temperature were found to increase the rates of the reactions. The addition of water affected b oth the rate of the reactions and the products formed. The alkalinity or acidity of the substrate was also observed to affect t he products formed and the mechanism of the reaction. The chemical warfare agents VX (O-ethyl S-(2-N,N-(diisopropylamino)ethyl) methylphosphonothio- late), sulfur mustard (bis(2-chloroethyl) sulfide, HD), So man (GD, pinacolyl methylphosphonofluoridate, O-1,2,2-trimethylpropyl methylphosphonofluoridate), an d thickened GD (TGD, which is GD with�3% polymeric thickener added) are of interest due to the possibility of use by terrorist organizations and in global conflicts. Sulfur mustard was used during WWI and WWII (1), and in the Iran-Iraq war of the 1980's (2). Sulfur mustard is known for persistence in the en vironment, especially at the bottom of the ocean (3,4). The terrorist organization Aum Shinrikyo used Sarin (GB) in the Tokyo subway in March, 1995, killing 13 civilians, and VX in 1994 to kill a disgruntled ex-member (5). The results discussed here are part of a series of experiments performed to determine the degradation rates of agents on the environmentally prevalent substrates concrete, sand, asphalt and soil, and to determine any chemical properties of the substrates that may influence the degradation rates of the agents. This article summarizes the agent-substrate inter actions observed to date by the authors and other researchers, and highlights the influence the substrate has on the observed agent reactivity.