John R. Stuff

Atomic emission detection for the quantitation of trimethylsilyl derivatives of chemical-warfare-agent related compounds in environmental samples

Abstract Quantitation of nerve agent degradation products is needed to develop methods for analysis of environmental samples for verification of the Chemical Weapons Convention. A procedure has been characterized which involves formation of the trimethylsilyl esters of alkylmethylphosphonic acids using 1% trimethylchlorosilane in bis-(trimethylsilyl)trifluoroacetamide as a derivatizing agent. Eight phosphorus-containing acids were extracted from spiked water, wipes, and two soil samples at low ppm levels, prepared using solid-phase extraction with a strong anion-exchange column, and derivatized. A gas chromatograph (GC) interfaced to an atomic emission detector (AED) was used to quantitate the derivatives in order to determine the extraction and derivatization efficiencies for environmental sample preparation. Because elemental response factors for the AED are independent of the type of compound, quantitation can be accomplished using an external standard, for which dimethylmethylphosphonate (DMMP) is used. The derivatization efficiencies ranged from 80% to 110% (six trials, with R.S.D. in the range 2–7%). The extraction efficiencies ranged from 13% to 99% in water, and they were lower from the soil and wipes. Gas chromatography-mass spectrometry of the derivatives was used to provide positive identifications.

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.

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.

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.

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.

Separation of cations in buffered 1-methyl-3-ethylimidazolium chloride-aluminum chloride ionic liquids by ion chromatography

Abstract Ion chromatography was used to separate sodium and 1-methyl-3-ethylimidazolium cations in the buffered 1-methyl-3-ethylimidazolium chloride—aluminum chloride room-temperature molten salt system. The calibration curves for the two species were linear over three decades and the accuracy of the method was ±2.8% relative error.

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.