Characterization of equimolar VX–water reaction product by gas chromatography–mass spectrometry

Rohrbaugh, D. K.

doi:10.1016/s0021-9673(98)00148-4

Cited by 33 publications

(21 citation statements)

References 10 publications

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“…EMPA is a well-known hydrolysis product of VX (Rohrbaugh 1998). We confirmed, experimentally, that Pyro A was produced by reaction of VX and EMPA by preparing a DCM solution containing both VX and EMPA, each at 50 ppm and then monitoring the solution composition over the course of several days.…”

Section: Comment On Vx Stabilitysupporting

confidence: 67%

Stability Study for Ultra-Dilute Chemical Warfare Agent Standards

Leif¹,

Koester²,

Mulcahy³

2012

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Executive SummaryUltra-dilute (10 ppm) chemical warfare agent (CWA) standards are being supplied to the Environmental Response Laboratory Network (ERLN) laboratories to allow the use of authentic standards to assist in analyses required in the aftermath of a terrorist attack with CWAs. It is critical for the ERLN laboratories to be able to work with authentic CWA standards to allow the unambiguous identification and quantification of CWAs. The ultradilute standards are synthesized in-house for use in analytical method development by the ERLN laboratories. However, data regarding the long-term stability of the ultra-dilute standards are lacking. For this reason, a study was undertaken to monitor the concentrations of CWAs in ultra-dilute standards as a function of time, under normal conditions of storage and use. The data collected in such a study could then be used to estimate reliable holding times for the ultra-dilute standards.CWAs in single-component and five-component standard solutions, containing 510 ppm each CWA in hexane and dichloromethane (DCM), were studied. The CWAs studied included sarin (GB), soman (GD), cyclohexylsarin (GF), sulfur mustard (HD), and O-ethyl-S-(2-diisopropylaminoethyl) methylphosphonothioate (VX). The specific objectives were the following:1. Measure the stability, over the course of 12 months, of single-component ultradilute (10 ppm) CWA standards that were stored at 4 C in the dark, 2. Measure the stability over the course of 12 months of multiple-component ultradilute (510 ppm) CWA standards that were stored at 4 C in the dark, 3. Determine if CWA stability differs in single-and multiple-component mixtures, 4. Determine if solvent choice (hexane versus DCM) affected holding time, and 5. Compare the stabilities of CWA standards stored in flame-sealed amber glass ampoules versus CWA standards stored in amber glass vials closed with Teflonlined, silicone septa screw caps that were opened and closed periodically.After the CWA standards were prepared in the desired solvent, 1-mL aliquots were transferred to amber glass ampoules and flame-sealed or transferred to screw-capped vials. All ampoules and vials were stored at 4°C ± 2 °C in a refrigerator. Duplicate ampoules/vials were opened at predetermined times and CWA concentrations were measured using a gas chromatograph coupled with a flame photometric detector (GC-FPD). CWA concentrations were plotted as a function of time over the course of one year. Selected samples were also analyzed by gas chromatography/mass spectrometry (GC/MS) to identify contaminants/degradation products.Estimated holding times for CWA standards under different conditions were determined using Dunnett's Test (Hsu 1996) to identify the time point before which a statistically significant decrease in analyte concentration occurred; see Table 1. Results for individual standards stored in sealed ampoules showed that the CWA standards made in DCM were stable for a year. Individual standards of CWAs stored in hexane and in sealed ampoules showed varying stabili...

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Section: Comment On Vx Stabilitysupporting

confidence: 67%

Stability Study for Ultra-Dilute Chemical Warfare Agent Standards

Leif¹,

Koester²,

Mulcahy³

2012

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“…At pH values of < 6 and > 10, cleavage of the P-S bond predominates, resulting in formation of ethyl methylphosphonic acid (EMPA) and diisopropylethyl mercaptoamine (DESH). The latter compound can be oxidized to bis(2-diisopropylaminoethyl) disul Rohrbaugh (249) identified the following impurities in a stored ton container of VX (identification was by direct gas chromatography-mass spectrometry analysis): diisopropylamine (0.7%), 0, 0-diethyl methylphosphonate (0.6%), 0,0-diethyl methylphosphonothioate (0.4%), 2-(diisopropylamino) ethane thiol (1.4%), 0,5-diethyl methylphosphonothioate (0.6%), 2-(diisopropylamino)ethyl vinyl sulfide (0.1%), 2-(diisopropylamino)ethyl ethyl sulfide (0.2%), 0, 0-diethyl dimethylpyrophosphonate ethyleneimmonium ion (CH2)2N + (C3H7)2 to form bis(2-diisopropylaminoethyl) sulfide. In a solution of 0.01 M VX and aqueous 0.1 M NaOH, VX was hydrolyzed to EMPA and S-(2-diisopropylaminoethyl) methylphosphonothioic acid (EA 2192) ions in a ratio of 87% to 13%, respectively; under these conditions, the half-life of VX was 31 min (253).…”

Section: Gdmentioning

confidence: 99%

The sources, fate, and toxicity of chemical warfare agent degradation products.

Munro

Talmage

Griffin

et al. 1999

Environ Health Perspect

527

501

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We indude in this review an assessment of the formation, environmental fate, and mammalian and ecotoxicity of CW agent degradation products relevant to environmental and occupational health.These parent CW agents indude several vesicants: sulfur mustards [undistilled sulfur mustard (H), sulfur mustard (HD), and an HD/agent T mixture (HT)]; nitrogen mustards [ethylbis(2-chloroethyl)amine (HN1), methylbis(2-chloroethyl)amine (HN2), tris(2-chloroethyl)amine (HN3)], and Lewisite; four nerve agents {O0ethyl S.[2-(diisopropylamino)ethyl] methylphosphonothioate (VX), tabun (GA), sarin (GB), and soman (GD)}; and the blood agent cyanogen chloride. The degradation processes considered here include hydrolysis, microbial degradation, oxidation, and photolysis. We also briefly address decontamination but not combustion processes. Because CW agents are generally not considered very persistent, certain degradation products of significant persistence, even those that are not particularly toxic, may indicate previous CW agent presence or that degradation has occurred. Of those products for which there are data on both environmental fate and toxicity, only a few are both environmentally persistent and highly toxic. Major degradation products estimated to be of significant persistence (weeks to years) indude thiodiglycol for HD; Lewisite oxide for Lewisite; and ethyl methyl phosphonic acid, methyl phosphonic acid, and possibly S.(2-diisopropylaminoethyl) methylphosphonothioic acid (EA 2192) for VX. Methyl phosphonic acid is also the ultimate hydrolysis product of both GB and GD. The GB product, isopropyl methylphosphonic acid, and a dosely related contaminant of GB, diisopropyl methylphosphonate, are also persistent. Of all of these compounds, only Lewisite oxide and EA 2192 possess high mammalian toxicity. Unlike other CW agents, suifur mustard agents (e.g., HD) are somewhat persistent; therefore, sites or conditions involving potential HD contamination should include an evaluation of both the agent and thiodiglycol.

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“…1B. Thus, efforts to identify VX degradation products using mass spectral interpretation often have relied on CI mass spectrometry [4][5][6][7] as knowledge of pseudomolecular ions [M+X] + (where X is a proton or expected CI reagent adduct) is of great help in unambiguously identifying these analytes. To protect the health of military forces, first responders, or the general public in a scenario where VX exposure is possible, a small field-portable GC-MS system capable of separating and identifying these molecules would be useful.…”

Section: Introductionmentioning

confidence: 99%