31P MAS NMR: a useful tool for the evaluation of VX natural weathering in various urban matrixes.

The fate of chemical warfare agent VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate) in various urban matrixes was monitored utilizing 31P MAS NMR. Chosen matrixes represent buildings, roads, pavement, and earth found in urban environments. In view of the high toxicity of VX, solid state NMR afforded a fairly safe experimental mode, omitting any chance for evaporation. Moreover, due to the nondestructive nature of these experiments, measurements could be repeated over and over using the same samples. Degradation rates of VX were obtained and compared to provide a list of relative reactivity toward VX: concrete > desert sand > beach sand > asphalt approximately to bitumen sheet. Chemical interactions between VX, its degradation products, and the matrixes were often expressed by widening of the peaks to the extent that mass balance could not be achieved. It is noteworthy that these experiments were usually carried out on crushed or milled specimens, allowing high reactivity and rapid reactions.