Extraction of Nerve Agent VX from Soils

Abstract

The development and optimization of a method allowing the extraction of intact organophosphorus chemical warfare agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX) from several types of soils are presented here. This involved the selection of an appropriate buffer to bring the sample to a pH close to the pK(a) of VX but sufficiently low to avoid its basic hydrolysis. Buffering with Tris (pH 9) and subsequent extraction of the aqueous layer by a 85:15 (v/v) hexane/dichloromethane mixture allows rapid and sensitive flame photometric detection of VX at spiking levels lower than 10 microg x g(-1), even after 3 months of aging. Extraction yields were close to 60% in complex matrixes. This method also allows recovery and identification of a characteristic degradation product of VX, bis(2-diisopropylaminoethyl) disulfide, which appears to be formed during the aging process. The performance of this method is far better than that of OPCW reference operating procedure, which does not allow extraction of detectable amounts of VX (spiked at 10 microg x g(-1)) in one of the soils used for this study.

Analysis of nerve agent degradation products in high‐conductivity matrices by transient ITP preconcentration and CZE separation coupled to ESI‐MS

“…Electrophoresis 2009,30,[1522][1523][1524][1525][1526][1527][1528][1529][1530] configuration) and to the fact that, as already observed, the ionization efficiency decreases upon decreasing molecular size [28,[37][38][39]. As for soil extracts, repeatability of migrations times was very satisfactory, with RSD values (n 5 6) comprised between 1.79 and 1.87% (Table 2).…”

“…Blank soil extracts were prepared from 10 g of local soil samples that were submitted to pressure-assisted solvent extraction with water at 150 bar and 1001C in a Dionex ASE 200 instrument (Dionex, Voisins-le-Bretonneux, France) [30]. The obtained aqueous soil extracts were next percolated through a cation exchange cartridge (AG50WX8 resin, BioRad Laboratories, Marnes-la-Coquette, France), then concentrated by partial evaporation to a volume of 2 mL (corresponding to an enrichment factor of 5) or to a volume of 1 mL (corresponding to an enrichment factor of 10).…”

Evidence of VX nerve agent use from contaminated white mustard plants

“…Generally, the smaller the particles the longer a nerve agent persists due to absorption over a larger surface area. However, the relationship between particle size and persistence in soil is complex, because persistency depends on the organic content, clay content and pH [17,[31][32][33]. Organic matter in soil varies from 1% to more than 50% and an increasing amount usually increases persistency.…”

Nerve Agents and Their Detection

“…Soils contaminated with Vseries agent was extracted with mixture of DCM and hexane. The analysis was accomplished with high sensitivity based on gas chromatography (GC) with flame photometric detection (FPD) [46].…”