Applications nerve agents

The recent development and comparative application of modern separation techniques with regard to determination of alkylphosphonic acids and lewisite derivatives have been demonstrated. This report highlights advantages and shortcomings of GC equipped with mass spectrometry detector and HPLC as well as CE with UV-Vis detector. The comparison was made from the sampling point of view and separation/detection ability. The derivatization procedure for GC of main degradation products of nerve agents to determine in water samples was applied. Direct determination of lewisite derivatives by HPLC-UV was shown. Also optimization of indirect determination of alkylphosphonic acids in CE-UV was developed. Finally, the new instrumental development and future trends will be discussed. 

This class of agents is not covered by the Chemical Weapons Convention. Because of the toxicity of the agents and lack of commercial application, carbamate nerve agents would be prohibited based on the Guidelines for Schedules of Chemicals. 

The potential use of foams has also been demonstrated for the decontamination of nerve agents [80]. In these applications, the detoxification of the nerve agent was carried out by immobilizing the enzyme organophosphorous acid anhydrase within either a fire fighting or blast-containment foam carrier. 

Organophosphate and carbamate cholinesterase inhibitors (see Chapter 7) are widely used to kill insects and other pests. Most cases of serious organophosphate or carbamate poisoning result from intentional ingestion by a suicidal person, but poisoning has also occurred at work (pesticide application or packaging) or, rarely, as a result of food contamination or terrorist attack (eg, release of the chemical warfare nerve agent sarin in the Tokyo subway system in 1995). 

Following the first reports in the literature of catalytic imprinted beads, a number of authors also reported applications of this polymer format to several imprinting systems. Busi et al. [64] reported the preparation of catalytic active beads for the Diels-Alder reaction using a TSA as a template. Jakubiak and co-workers developed imprinted beads for the oxidation of phenols based on a Cu(II) complex as catalytic centre [65]. Say and collaborators described the synthesis of microbeads also based on a Cu(II) complex with esterase activity towards paraoxon (60), a potent nerve agent [66]. The imprinted beads enhanced the rate of reaction over the non-imprinted polymer by a factor of 40, as resulted from the ratio of the corresponding kciil. 

Application of in vitro test methods have become advantageous in specific cases, such as structurally defined compounds and delayed neuropathy, since target cell data and biochemical processes associated in delayed neuropathy are known. Microscopic studies reveal that cases of OPIDN have degeneration of axons followed by demyelination of the nervous system.25,26 Epidemiologic studies have indicated mild impairment of the brainstem, spinal cord, and peripheral nerve functions in Gulf War veterans.27 Such studies are consistent with the spectrum of OPIDN syndrome. The main nerve agents have been shown to inhibit NTE in vitro as well as in vivo. Sarin has been shown to produce delayed neurotoxicity when administered at higher doses in protected hens.25-27... 

R.M. Black, R.J. Clarke, R.W. Read and M.T.J. Reid, Application of gas chromatography-mass spectrometry and gas chromatography-tandem mass spectrometry to the analysis of chemical warfare samples, found to contain residues of the nerve agent sarin, sulfur mustard and their degradation products, J. Chromatogr., A, 662, 301-331 (1994). 

Nerve agents hydrolyze sufficiently slowly to be analyzed by LC/MS under reversed phase conditions. Although analyses for nerve agents alone are usually performed by GC-based methods, there are scenarios, for example, screening of water samples, in which LC/MS offers a rapid alternative. LC/MS is particularly useful for combined analysis of agents and degradation products. A number of applications have recently been reported for the... 

It is unlikely that the unchanged nerve agent would be detected in the blood or tissues of a casualty unless samples were collected very soon after the exposure. A number of methods have been reported for the analysis of nerve agents in blood, for application to animal studies. These involve simple liquid or SPE extraction, for example, using chloroform (sarin, soman) (47), C18 SPE (sarin, soman) l48 49 , ethyl acetate (VX) (50), usually after precipitation of proteins, and analysis by GC/MS or gas chromatography/nitrogen-phosphorus detection (GC/NPD). Sarin bound to cholinesterase and displaced with fluoride ion was extracted by C18 SPE (see Part B) (51). 

Environment. Detection of environmental degradation products of nerve agents directly from the surface of plant leaves using static secondary ion mass spectrometry (sims) has been demonstrated (97). Pinacolylmethylphosphonic acid (PMPA), isopropylmethylphosphonic acid (IMPA), and ethylmethylphosphonic acid (EMPA) were spiked from aqueous samples onto philodendron leaves prior to analysis by static sims. The minimum detection limits on philodendron leaves were estimated to be between 40 and 0.4 ng/mm2 for PMPA and IMPA and between 40 and 4 ng/mm2 for EMPA. Sims analyses of IMPA adsorbed on 10 different crop leaves were also performed in order to investigate general applicability of static sims for... 

We have 12 separate filter systems at the site ranging from 333 to 15,000 CFM (Inclosure 23). A typical application is the ADS - the facility used to destroy the nerve agents GB VX by chemical neutralization (Inclosure 2U) GB with NaOH and VX by an acid chlorination process. The actual filter system installation is shown in Inclosure 25 and has a capacity of 15,000 CFM. These filter units consist of a low efficiency particulate prefilter, a high efficiency particulate HEPA filter. 

Applied to cotton in 43 out of 81 cotton producing countries, the nerve agent deltamethrin, is probably the most extensively applied cotton pesticide in the world. Global sales on cotton applications amount to some US 40 million, placing deltamethrin among the top 10 pesticides applied to cotton globally. These sales account for over one quarter of deltamethrin applications within the global crop sector. 

Tak, V. et al. Application of Doehlert design in optimizing the determination of degraded products of nerve agents by ion-pair liquid chromatography electrospray ionization tandem mass spectrometry, J. Chromatogr. A. 2007,1161,198-206. 

It should be further noted that the effects of nerve agents on GABAergic transmission in the CNS may have imph-cations for behavioral effects in laboratory animals and humans, and may also contribute to the induction of convulsions at higher doses (Bakshi et al, 2000). Nevertheless, given the present undefined application of non-cholinergic data to whole-body estimations, reliance on the primary assumption of AChE action is consistent with recognized opinion (Bakshi et al, 2000). 

For comparison, it is usefiil to consider other common guideline sources applicable to short-term nerve agent release events. The US Department of Energy, in their development of 1 h Protective Action Concentrations/ Temporary Emergency Exposure Levels (PAC/TEELS), has chosen to replicate the published nerve agent-specific 1 h AEGL-1, -2, and -3 values as Tier 1, Tier 2, and Tier 3 PAC/TEEL values, respectively (see http //hss.energy.gov/ HealthSafety/WSHP/chem safety/teel.html). 

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