H. Dupont Durst

Quantitation of Chemical Warfare Agents Using the Direct Analysis in Real Time (DART) Technique

Direct analysis in real time (DART) is an ion source that permits rapid mass spectrometric detection of gases, liquids, and solids in open air under ambient conditions. It is a unique technology in the field of chemical weapons detectors in that it does not require a vapor pressure, does not require sample preparation, and is nondestructive to the original sample. While the DART technique has had success as a first line instrument of detection, there have been lingering doubts over the techniques quantitative reliability and reproducibility. Here, we demonstrate its capability to produce linear calibration curves (R(2) = 0.99 or better) for the nerve agents GA, GB, and VX as well as the blister agent HD. Independently prepared check standards measured against these curves typically have recovery errors less than 3%. We show the DART instrument response to be linear over roughly 3 orders of magnitude. Furthermore, this study shows that averaging as few as three measurements for each data point is sufficient to produce high quality calibration curves, thus reducing data collection time and providing quicker results.

Separation of sulfur containing chemical warfare related compounds in aqueous samples by micellar electrokinetic chromatography

Abstract A method is described in which micellar electrokinetic chromatography (MEKC) is used to separate thiodiglycol, 2,2′-sulfinyldiethanol, 1,4-dithiane, 1,4-thioxane, O-isobutyl methylphosphonothioic acid and O-ethyl methylphosphonothioic acid in aqueous samples. Detection limits range from 1 to 10 μg/ml and the calibration curves are linear over two orders of magnitude. The compounds are separated in under 10 min. The method fulfills our requirements for a rapid, on-site screening technique for these compounds.

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.

Thermal separation to facilitate Direct Analysis in Real Time (DART) of mixtures

We explore a thermal separation technique for use with Direct Analysis in Real Time (DART). By applying gas temperature ramping, we are able to disburse a mixture of compounds in time. The three components were selected to create a challenging mixture that would not likely be discerned solely using exact mass capabilities. While the thermal separation technique is of low resolution, it preserves the inherent rapid, non-contact, ambient characteristics of the ion source.

Detection of the chemical warfare agents bis-(2-chloroethyl)ethylamine (HN-1) and tris-(2-chloroethyl)amine (HN-3) in air

This paper describes the method development and validation for detection of the chemical warfare agents HN-1 and HN-3 in air using C8 solid-phase extraction disks followed by liquid desorption and analysis by gas chromatography. The method is contrasted to the standard approach which uses solid sorbent tubes followed by thermal desorption and analysis by gas chromatography.

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.

Vapor-Phase Infrared Spectral Study of Analogs of the Nerve Agent Sarin

Abstract Analogs of the chemical warfare agent Sarin were synthesized using a microscale technique and analyzed with a gas chromatograph equipped with a light pipe Fourier Transform infrared spectrometer. Produced as byproducts of the chemical warfare agents, a variety of related organophosphonate byproducts were often also observed. Similarities and differences among the spectra within the classes are noted, including some distinguishing characteristics of the infrared spectra not previously cited in the literature.

Group 13 chelates in nerve gas agent and pesticide dealkylation

Schiff base boron and aluminium bromides have been used to cleave organophosphate nerve agents and pesticides and their simulants: salben(tBu)[BBr2]2 was very effective in cleaving the VX simulants EMPPT and DEPPT and nerve agent VX; salen(tBu)AlBr was effective in cleaving the nerve agents VX and Soman and the pesticideDiazinon.

Aluminium sulfate and sodium aluminate buffer solutions for the destruction of phosphorus based chemical warfare agents

Nerve agents VX and GB (sarin) are sequestered and removed by aluminium sulfate and sodium aluminate mixtures adjusted to pH 4 in solution. The products of hydrolysis are removed with the alum floc below NMR detection limits over time depending and the amount of aluminium molar excess relative to agent. Half-lives for GB decomposition are 3.1 h and 1.1 h, respectively, for a 120 and a 1200 molar excess. For VX, the half-lives are 8.5 d and 2.9 d for a 240 and a 5000 molar aluminium excess. In the case of GB, fluorine is sequestered as the hexafluoroaluminate ion. In the case of VX, no phosphorus containing hydrolysis products including the very toxic S-[2-(diisopropyl-amino)-ethyl]methylphosphonothiolate (EA-2192) are detected in the hydrolysate.

Further studies into the feasibility of using aqueous alum solutions in the destruction of VX

The destruction of phosphorus based chemical warfare agents using aqueous buffer mixtures of aluminum sul- fate (alum) and sodium aluminate is pursued. The production of VX (O-ethyl-S-(2-(diisopropylamino)ethyl)-methylphos- phonothiolate) hydrolysis products ethyl methyl phosphonic acid (EMPA), an aluminum complex of EMPA, and S-(2- (diisopropylamino)ethyl)methylphosphonothiolate (EA-2192) is characterized in acidic and basic alum buffers. The study employs 31 P high resolution magic angle nuclear magnetic resonance spectroscopy (HRMAS NMR) for both quantitative and qualitative analysis. The acidic buffer results in a slower reaction rate and is less effective than the basic buffer.