Kevin M. Morrissey

Identification of chemical-weapons-related compounds in decontamination solutions and other matrices by multiple chromatographic techniques

Abstract Several applications have arisen for the high confidence identification of chemical weapons agents and related compounds in toxic waste or other complex matrices. Three examples of analysis of agents or byproducts are presented: GA (ethyl N,N-dimethylphosphoramidocyanidate, or tabun) and synthetic byproducts in an complex organic liquid solution; HD [bis(2-chloroethyl)sulfide, or mustard gas] in a decontamination solution; and VX (S,2-diisopropylaminoethyl ethyl methylphosphonothioate) and a toxic hydrolysis product (S,2-diisopropylaminoethyl methylphosphonothioic acid, also known as EA-2192). Multiple chromatographic methods were used to unequivocally identify low concentrations of agent with high confidence, including results from gas chromatographic analysis with mass spectral detection (with electron impact or chemical ionization), infrared detection, atomic emission detection and flame photometric detection, as well as liquid chromatography–tandem mass spectrometry.

Multiple-technique analytical characterization of a mixture containing chemical-weapons simulant from a munition

An amber yellow organic liquid was found in a munition shell at Dugway Proving Grounds, UT, USA, that was likely used as a simulant of chemical weapons. The primary analytical techniques to characterize the mixture were gas chromatography-infrared detection-mass spectral detection (GC-IR-MS); liquid chromatography-mass spectrometry (LC-MS); nuclear magnetic resonance (NMR) using the nuclei 1H, 13C and 31P; and gas chromatography-atomic emission detection (GC-AED). Six major phosphorus-containing components were identified and confirmed by at least three techniques, and several additional phosphorus-containing components of lower concentration have been identified by GC-IR-MS and LC-MS. Five major non-phosphorus components, including ethyl acetate, diethyl sulfide and dibutylamine, have been identified by multiple techniques. The major phosphorus compound (23.9+/-0.4 wt.%) was O,O,O-triethyl phosphorothioate (I) and the second most abundant (14.4+/-0.2 wt.%) was O,O,S-triethyl phosphorothioate (III). No VX, G-agent, or pesticide was observed in the sample, although III may be a cholinesterase inhibitor which produces delayed toxic response. III also produces a false hit for the pesticide cyanthoate when analyzed by GC-MS-EI. The mixture appears to have been formulated as a chemical warfare agent simulant, most likely as a challenge of agent detection techniques.

A decontamination system for chemical weapons agents using a liquid solution on a solid sorbent

A decontamination system for chemical warfare agents was developed and tested that combines a liquid decontamination reagent solution with solid sorbent particles. The components have fewer safety and environmental concerns than traditional chlorine bleach-based products or highly caustic solutions. The liquid solution, based on Decon Greentrade mark, has hydrogen peroxide and a carbonate buffer as active ingredients. The best solid sorbents were found to be a copolymer of ethylene glycol dimethacrylate and n-lauryl methacrylate (Polytrap 6603 Adsorber); or an allyl methacrylate cross-linked polymer (Poly-Pore E200 Adsorber). These solids are human and environmentally friendly and are commonly used in cosmetics. The decontaminant system was tested for reactivity with pinacolyl methylphosphonofluoridate (Soman, GD), bis(2-chloroethyl)sulfide (Mustard, HD), and S-(2-diisopropylaminoethyl) O-ethyl methylphosphonothioate (VX) by using NMR Spectroscopy. Molybdate ion (MoO(4)(-2)) was added to the decontaminant to catalyze the oxidation of HD. The molybdate ion provided a color change from pink to white when the oxidizing capacity of the system was exhausted. The decontaminant was effective for ratios of agent to decontaminant of up to 1:50 for VX (t(1/2) < or = 4 min), 1:10 for HD (t(1/2) < 2 min with molybdate), and 1:10 for GD (t(1/2) < 2 min). The vapor concentrations of GD above the dry sorbent and the sorbent with decontamination solution were measured to show that the sorbent decreased the vapor concentration of GD. The E200 sorbent had the additional advantage of absorbing aqueous decontamination solution without the addition of an organic co-solvent such as isopropanol, but the rate depended strongly on mixing for HD.

On-line monitoring system for chemical warfare agents using automated capillary micellar electrokinetic chromatography

We present an automated analysis system for the detection of the chemical warfare blister agents, sulfur mustard (HD) and lewisite (L), in aqueous samples without any chemical derivatization. The system is compact in size and designed to operate in the field in a safe, autonomous manner for near real-time monitoring applications. It uses anionic surfactant-based capillary micellar electrokinetic chromatography (MEKC) to separate the sample followed by UV detection. The analysis time is sufficiently fast to allow direct detection of HD which enabled the estimation of effective hydrolysis rates in the aqueous sample matrix. The estimated hydrolysis half-life of HD in our system was 4.85 ± 0.05 min. The detection limit of HD was determined to be 10 ppm with a signal to noise ratio of 5. By contrast, L hydrolyzed too rapidly in aqueous samples to enable direct detection. Instead the first hydrolysis product 2-chlorovinyl arsonous acid (CVAA), also considered a blister agent, was detected with a detection limit of 0.7 ppm with a signal to noise ratio of 5.

Reaction of VX and GD with gaseous ozone

Attempts at decontaminating nerve agents VX {O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate} and GD (pinacolyl methylphosphonofluoridate) with gaseous ozone are described. VX reacts like a tertiary amine with oxidation occurring at carbons adjacent to the nitrogen. In this manner a variety of novel VX derivatives still possessing intact P–S bonds are generated, and as such, must be considered to retain formidable toxicity. The major product is O-ethyl S-[2-(isopropylamino)ethyl] methylphosphonothioate. No reaction of GD with ozone occurs under the conditions employed.