Development of the HS-SPME-GC-MS/MS method for analysis of chemical warfare agent and their degradation products in environmental samples

After World War II approximately 50,000 tons of chemical weapons were dumped in the Baltic Sea by the Soviet Union under the provisions of the Potsdam Conference on Disarmament. These dumped chemical warfare agents still possess a major threat to the marine environment and to human life. Therefore, continue monitoring of these munitions is essential. In this work, we present the application of new solid phase microextraction fibers in analysis of chemical warfare agents and their degradation products. It can be concluded that the best fiber for analysis of sulfur mustard and its degradation products is butyl acrylate (BA), whereas for analysis of organoarsenic compounds and chloroacetophenone, the best fiber is a co-polymer of methyl acrylate and methyl methacrylate (MA/MMA). In order to achieve the lowest LOD and LOQ the samples should be divided into two subsamples. One of them should be analyzed using a BA fiber, and the second one using a MA/MMA fiber. When the fast analysis is required, the microextraction should be performed by use of a butyl acrylate fiber because the extraction efficiency of organoarsenic compounds for this fiber is acceptable. Next, we have elaborated of the HS-SPME-GC-MS/MS method for analysis of CWA degradation products in environmental samples using laboratory obtained fibers The analytical method for analysis of organosulfur and organoarsenic compounds was optimized and validated. The LOD's for all target chemicals were between 0.03 and 0.65 ppb. Then, the analytical method developed by us, was used for the analysis of sediment and pore water samples from the Baltic Sea. During these studies, 80 samples were analyzed. It was found that 25 sediments and 5 pore water samples contained CWA degradation products such as 1,4-dithiane, 1,4-oxathiane or triphenylarsine, the latter being a component of arsine oil. The obtained data is evidence that the CWAs present in the Baltic Sea have leaked into the general marine environment.     

Utilisation of separation methods in the analysis of chemical warfare agents

Chemical warfare agents and their degradation products represent a broad group of compounds with different chemical properties (polarity, volatility, thermostability, etc.). These chemicals often have to be detected and determined in complex matrices and therefore highly efficient separation techniques hyphenated to selective and sensitive detectors play an indispensable role. This review offers an overview of selected papers devoted to the title subject. It cannot be considered as a comprehensive literature compilation but should allow the reader to obtain an insight into the application of separation techniques in the important area of human protection and control of chemical weapons.     

Gas chromatographic separation of the stereoisomers of organophosphorus chemical warfare agents using cyclodextrin capillary columns

The synthesis of the organophosphorus nerve agents sarin, tabun, and cyclohexyl methylphosphonofluoridate (GF) produces a mixture of two stereoisomers except for soman where four stereoisomers are produced. Significant differences exist in the reported toxicity and AChE inhibition rates of the various stereoisomers. This makes the ability to distinguish between the different stereoisomers desirable. Five different derivatized cyclodextrin stationary phases developed for gas chromatography were tested for their ability to resolve the nerve agent stereoisomers using a gas chromatograph interfaced to an atomic emission detector. Of the five columns that we examined, only the 2,6-di-O-pentyl-3-O-trifluoroacetyl or 2,6-di-O-pentyl-3-O-butyryl γ-cyclodextrins were able to successfully resolve all four soman stereoisomers. The elution order for each column was determined using solutions of isolated soman stereoisomers. Enantiomers of sarin, tabun, and GF were resolved with varying degrees of success on the different cyclodextrin stationary phases. Only the butyryl γ-cyclodextrin was able to separate the enantiomers of all four of the nerve agents examined in this study. The capacity (k) and selectivity (α) factors were determined for each of the chemical warfare agents successfully separated. The TNO Prins Maurits Laboratory in the Netherlands has previously developed several different chromatographic methods to resolve the stereoisomers of soman, sarin, and tabun. The advantage of the method described here is that commercially available cyclodextrin gas chromatography columns were used to resolve the stereoisomers, thereby facilitating rapid and routine analysis of organophosphorus nerve agents.     

荧光法检测化学战剂

化学战剂,包括神经性毒剂(如沙林、VX)和糜烂性毒剂(如芥子气),属于剧毒化学品,能够严重危害国家安全和环境安全.因此,针对各类化学战剂,开发简单、快速、可便携化、高灵敏度和高选择性的荧光检测技术具有重要的意义.本文综述了近年来国内外荧光法检测化学战剂的研究进展,并对该领域所面临的挑战和未来发展方向进行了总结和展望.     

FT-IR analysis of chemical warfare agents

The qualitative and quantitative FT-IR analyses of dilute aqueous solutions of GA (tabun), GB (sarin), GD (soman), and VX were evaluated using the CIRCLE CELL^TM. Infrared spectra were recorded using a Nicolet 60SX FT-IR spectrometer fitted with a liquid nitrogencooled MCTA detector. The CIRCLE CELL^TM used a high pressure micro-flow-through sampling accessory fitted with a ZnSe internal reflection element. Peak heights were evaluated with the Nicolet SUPER QUANT program after spectral subtraction of the solvent. TheP=0 stretching absorption band, centered around 1240 cm^–1 for theG-type agents and 1180 cm^–1 for VX, produced good quantification. At a concentration of 2.0 mg/ml for theG-type agents and 1.0 mg/ml for VX, quantitative analysis produced coefficients of variation of 3% or less. The detection limit was observed to be around 0.1 mg/ml.This work was performed at the US Army Medical Research Institute of Chemical Defense and funded by the US Army Medical Research and Development Command under the provisions of the Intergovernmental Personnel Act of 1970 (P.L. 91-648).The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense     

Heat characteristics of chemical warfare agents

The heat characteristics of sulfur mustard (H), Lewisite (L), LI, LII, LIII, yellow agent (1:1 mass/mass H and L) and H heels were investigated by thermogravimetric - differential thermal analysis (TG-DTA). The object of this study was to provide details of the effectiveness of elevated temperature on the decomposition of these agents in both an active atmosphere (air) and an inert atmosphere (nitrogen). TG-DTA measured object mass change and heat radiation/absorption corresponding to regulated temperature changes of the test materials. All agents, with the exception of one of the H heels, exhibited an endotherm suggesting evaporation of the agents rather than oxidation.     

Rapid screening of precursor and degradation products of chemical warfare agents in soil by solid-phase microextraction ion mobility spectrometry (SPME-IMS)

The use of solid-phase microextraction (SPME) coupled to ion mobility spectrometry (IMS) to detect precursor and degradation products of chemical warfare agents (CWAs) as soil contaminants was investigated. The development and characterization of a system to interface a thermal desorption solid-phase microextraction inlet with a hand held ion mobility spectrometer was demonstrated. The analytes used in this study were diisopropyl methylphosphonate (DIMP), diethyl methylphosphonate (DEMP), and dimethyl methylphosphonate (DMMP). Two SPME fibers with different stationary phases, 100 μm polydimethylsiloxane (PDMS) and 65 μm polydimethylsiloxane divinylbenzene (PDMS/DVB), were evaluated in this study to determine the optimal fiber and extraction conditions. Better results were obtained with the PDMS fiber. SPME-IMS offered good repeatability and detection of the precursor and degradation products in spiked soil at concentrations as low as 10 μg/g. Sample analysis time was less than 30 min for all the precursor and degradation products.     

Hydrogen-bonding interactions in crown-(thio)urea complexes with anions,chemical warfare agents and simulants

ABSTRACT

Benzocrown ethers incorporating phenyl and nitrophenyl urea and thiourea moieties were synthesised. Both the nitrophenyl urea and thiourea derivative gave a fluoride-specific colorimetric response but only the urea derivative bound the organophosphonate nerve agent simulants dimethyl methylphosphonate (DMMP) and diisopropyl methylphosphonate (DIMP). This suggested an application as sensors for the nerve agents sarin, soman and cyclosarin which release fluoride upon hydrolysis. Although no fluoride-induced response was observed in the UV-visible spectrum, binding to soman was determined by ¹H NMR. DFT computational simulations suggested that the two crowns adopt different conformations in which both can bind fluoride but only the urea derivative can bind DMMP, DIMP and soman. The results show that, for this system, simulant- and soman-binding behaviours are in good agreement.     

Analysis of chemical warfare agents in water by solid phase extraction and two-channel capillary gas chromatography

Solid phase extraction with commercial C-18 cartridges has been applied to the analysis of some well known chemical warfare agents in water samples. Different sample pretreatment and cartridge conditioning procedures, and different extraction solvents were tested to study the optimum conditions for efficient extraction and recovery of the compounds of interest. The eluates were analyzed with a two-channel gas chromatograph equipped with an autosampler and a retention index monitoring system. The suitability of this technique for real samples is discussed: the rapid hydrolysis of many of the compounds studied and the poor recoveries of the polar degradation products are practical limitations of the method.     

Determination of chemical warfare agents and related compounds in environmental samples by solid-phase microextraction with gas chromatography

Solid phase microextraction (SPME) is an increasingly common method of sample isolation and enhancement. SPME is a convenient and simple sample preparation technique for chromatographic analysis and a useful alternative to liquid-liquid extraction and solid phase extraction. SPME is speed and simply method, which has been widely used in environmental analysis because it is a rather safe method when dealing with highly toxic chemicals. A combination of SPME and gas chromatography (GC) permits both the qualitative and quantitative analysis of toxic industrial compounds, pesticides and chemical warfare agents (CWAs), including their degradation products, in air, water and soil samples. This work presents a combination of SPME and GC methods with various types of detectors in the analysis of CWAs and their degradation products in air, water, soil and other matrices. The combination of SPME and GC methods allows for low detection limits depending on the analyte, matrix and detection system. Commercially available fibers have been mainly used to extract CWAs in headspace analysis. However, attempts have been made to introduce new fiber coatings that are characterized by higher selectivities towards different analytes of interest. Environmental decomposition of CWAs leads to the formation of more hydrophilic products. These compounds may be isolated from samples using SPME and analyzed using GC however, they must often be derivatized first to produce good chromatography. In these cases, one must ensure that the SPME method also meets the same needs. Otherwise, it is helpful to use derivatization methods. SPME may also be used with fieldportable mass spectrometry (MS) and GC-MS instruments for chemical defense applications, including field sampling and analysis. SPME fibers can be taken into contaminated areas to directly sample air, headspaces above solutions, soils and water.     

Mass spectrometric analysis of chemical warfare agents and their degradation products in soil and synthetic samples

A packed capillary liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method was developed for the identification of chemical warfare agents, their degradation products and related compounds in synthetic tabun samples and in soil samples collected from a former mustard storage site. A number of organophosphorus and organosulfur compounds that had not been previously characterized were identified, based on acquired high-resolution ESI-MS data. At lower sampling cone voltages, the ESI mass spectra were dominated by protonated, sodiated and protonated acetonitrile adducts and/or their dimers that could be used to confirm the molecular mass of each compound. Structural information was obtained by inducing product ion formation in the ESI interface at higher sampling cone voltages. Representative ESI-MS mass spectra for previously uncharacterized compounds were incorporated into a database as part of an on-going effort in chemical warfare agent detection and identification. The same samples were also analyzed by capillary column gas chromatography (GC)-MS in order to compare an established method with LC-ESI-MS for chemical warfare agent identification. Analysis times and full-scanning sensitivities were similar for both methods, with differences being associated with sample matrix, ease of ionization and compound volatility. GC-MS would be preferred for organic extracts and must be used for the determination of mustard and relatively non-polar organosulfur degradation products, including 1,4- thioxane and 1,4-dithiane, as these compounds do not ionize during ESI-MS. Diols, formed following hydrolysis of mustard and longer-chain sulfur vesicants, may be analyzed using both methods with LC-ESI-MS providing improved chromatographic peak shape. Aqueous samples and extracts would, typically, be analyzed by LC-ESI-MS, since these analyses may be conducted directly without the need for additional sample handling and/or derivatization associated with GC-MS determinations. Organophosphorus compounds, including chemical warfare agents, related compounds and lower volatility hydrolysis products may all be determined during a single LC-ESI- MS analysis. Derivatization of chemical warfare agent hydrolysis products and other compounds with hydroxyl substitution would be required prior to GC-MS analysis, giving LC-ESI-MS a definite advantage over GC-MS for the analysis of samples containing chemical warfare agents and/or their hydrolysis products.     

In-line respeciation: an ion-exchange ion chromatographic method applied to the separation of degradation products of chemical warfare nerve agents in soil

The natural background of anions encountered when analyzing soil samples by ion chromatography (IC) present significant problems in the separation, detection and quantification of isopropyl methylphosphonic acid (IMPA) and methylphosphonic acid (MPA), the degradation products of sarin, a chemical warfare nerve agent. Using chemically-suppressed IC with conductivity detection, a commercially available ion-exchange column, and an isocratic binary eluent system, IMPA and MPA were determined in aqueous extracts of soil at sub-ppm (μg/g) concentrations without the need for gradient elution or organic solvent eluent modifiers. Common soil anions such as chloride, nitrate, sulfate and phosphate do not interfere with the analysis method due to the composition of the binary eluent allowing for greater mobilization of multivalent anions (e.g., MPA, carbonate, and sulfate) while monovalent anions (e.g., IMPA and nitrate) are relatively unaffected. Carbonate is selectively removed by in-line respeciation to bicarbonate.     

Mass spectrometric study of selected precursors and degradation products of chemical warfare agents

Selected precursors and degradation products of chemical warfare agents namely N,N-dialkylaminoethane-2-ols, N,N-dialkylaminoethyl-2-chlorides and some of related N-quaternary salts were studied by means of electrospray ionization-multiple tandem mass spectrometry (ESI-MS(n)). Proposed structures were confirmed with accurate mass measurement. General fragmentation patterns of these compounds are discussed in detail and suggested processes are confirmed using deuterated standards. The typical processes are elimination of alkene, hydrogen chloride, or water, respectively. Besides, elimination of ethene from propyl chain under specific conditions was observed and unambiguously confirmed using exact mass measurement and labelled standard. The potential of mass spectrometry to distinguish the positional isomers occurring among the studied compounds is reviewed in detail using two different MS instruments (i.e. ion trap and hybrid quadrupole-time of flight (Q-TOF) analyzer). A new microcolumn liquid chromatography (microLC)/MS(n) method was designed for the cases where the resolution based solely on differences in fragmentation is not sufficient. Low retention of the derivatives on reversed phase (RP) was overcome by using addition of less typical ion pairing agent (1 mM/l, 3,5-dinitrobenzoic acid) to the mobile phase (mixture water : acetonitrile).     

Degradation of chemical warfare agents by nickel doped titanium dioxide powders: Enhanced surface activity

Here, Nickel doped anatase TiO₂ samples were prepared and characterized by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, specific surface area (BET), porosity determination (BJH) and CO₂-TPD experiments. DFT calculation was conducted to investigate the oxygen vacancy formation energies and hydroxyl groups activity. The as-prepared Ni²⁺ doped TiO₂ samples were used for heterogeneous degradation of chemical warfare agents (CWAs) and a high degradation rate, 92.2% and > 99.5% for sulfur mustard (HD) within 1 h and 12 h, > 99.5% for soman (GD) in less than 30 min, and > 99.5% for VX in less than 5 min was achieved, which were significantly enhanced compared with commercial P25 and anatase TiO₂ nanoparticles under identical conditions. The formation of non-toxic hydrolysis products confirmed the nucleophilic hydrolysis pathway via surface reaction. Integration of experimental and computational methods could well illustrate that surface structure changes of TiO₂ after Ni²⁺ doping was the main reason for the superior stoichiometric activity towards CWAs.     

Spectroscopic and inclusion properties of G-series chemical warfare agents and their simulants: a DFT study

A computational protocol to predict the infrared spectra of chemical warfare agents (CWAs) tabun (GA), sarin (GB), soman (GD) and cyclosarin (GF) has been developed. Sarin was used to benchmark the method through gas phase simulations. DFT calculations using the EDF2 functional and diffuse 6-311++G** basis set was found to give the closest match to experimental infrared spectra. Using the same functional the 6-31G (2df, 2p) basis set was found to be superior when hydrated sarin was modelled. GA, GB, GD and GF, together with 11 commonly used simulants, were modelled in the gas and hydrated states. Complexes of GB and a number of CWA mimics with α-cyclodextrin were modelled to give insight into their different modes of inclusion.     

Anaerobic toxicity and biodegradability of hydrolysis products of chemical warfare agents

The toxicity and biodegradability of the main hydrolysis products of chemical warfare agents were investigated under methanogenic conditions. Among the tested substances, only MPhA does not have any toxic effect with regard to the aceticlastic methanogenic activity. The toxicity of other compounds varied between moderate (TDG, mercaptoethanol) to strong (ethanolamine, diisobutyl ester of MPhA). Biodegradability tests showed that all the products of chemical detoxification of mustard gas (ethanolamine, ethylene glycol, TDG, mercaptoethanol) can be biomineralized under methanogenic conditions. On the contrary, phosphorus-containing compounds from the chemical detoxification of nerve warfare agents (Sarin, Soman, V_x-gases) are quite persistent under these conditions.     

Determination of diphenylarsinic acid and phenylarsonic acid,the degradation products of organoarsenic chemical warfare agents,in well water by HPLC–ICP‐MS

Diphenylarsinic acid (DPAA) and phenylarsonic acid (PAA), which were degradation products of organoarsenic chemical warfare agents used as sternutatory gas, were detected in the well water at Kamisu, Ibaraki Prefecture, Japan. The standard material of DPAA was synthesized with aqueous arsenic acid and phenylhydrazine in order to determine organic arsenic compounds in well water. The DPAA showed a protonated ion at m/z 263 [M + H]⁺ and a loss of H₂O ion at m/z 245 [M + H ? H₂O]⁺ from protonated ion by the electrospray ionization time‐of‐flight mass spectrometry. The quantitative analysis of DPAA and PAA was performed by high‐performance liquid chromatography inductively coupled plasma mass spectrometry and the system worked well for limpid liquid samples such as well water. Copyright © 2005 John Wiley & Sons, Ltd.     

Liquid chromatography with mass-spectrometric detection for the determination of chemical warfare agents and their degradation products

This review summarizes the results of high-performance liquid chromatography with mass-spectrometric detection (HPLC-MS) in the identification of chemical warfare agents and their degradation products, obtained in the last 13 years passed since the ratification of the Convention on the Prohibition of the Development, Production, Stockpiling, and Use of Chemical Weapons and on Their Destruction (the Convention). The conditions of the separation and detection of compounds in a variety of ionization techniques (electrospray ionization, atmospheric pressure chemical ionization) and analyzers (time-of-flight (TOF), tandem mass spectrometry, triple quadrupole, ion trap) are considered. The detection limits of the degradation products are given; the possibility of identifying compounds and the methods of sample preparation using contemporary methods of preconcentration (solvent microextraction) and separation (use of various adsorbents, molecularly-imprinted polymers) are described. The features of the HPLC-MS analysis of environmental samples (water, soil) and biological fluids (urine, blood serum) are discussed. The review is focused on the determination of the degradation products and derivatives of nerve agents, that is, alkylphosphonic acids.     

Analysis of degradation products of chemical warfare agents using capillary electrophoresis

Analysis of chemical warfare agents (CWAs), their precursors and degradation products (DPs) is an important verification component in support of the Chemical Weapons Convention and urgently demanding rapid and reliable analytical methods. Considering a growing number of papers presented in the last years in the field of capillary electrophoresis (CE) of DPs, this review article gives an overview on CE techniques which are feasible for the determination of DPs with the advantages of using relatively simple and inexpensive research instrumentation, reduced consumption of potentially toxic samples, shorter sample preparation times, etc. A brief introduction is provided into the chemical background of CWAs followed by a documented appraisal that the CE method is well suited to deal with polar, acidic DPs mostly occurring in aqueous samples or extracts. Applications of CE to the separation of DPs are described, complemented by a critical discussion of the detection techniques, including mostly conductivity, laser-induced fluorescence, UV absorption and mass spectrometry. This review also includes actual development regarding the challenges of CE in analyses of different DPs from real samples, often avoided by in- and off-line pre-concentration techniques or the coupling of CE to selective detection methods. Special emphasis is placed on the miniaturised CE systems that have the potential of being before long developed into a field deployable and potentially disposable platform for routine DP monitoring in environmental samples.     

Determination of nerve agent degradation products in environmental samples by liquid chromatography-time-of-flight mass spectrometry with electrospray ionization

A powerful and rapid method has been developed for the identification and quantitative determination of alkyl methylphosphonic acids, which are the degradation products of nerve agents, using liquid chromatography-time-of-flight mass spectrometry with electrospray ionization. Six alkyl methylphosphonic acids were well separated within 16 min. For quantitative analysis, good linearity, sensitivity and reproducibility were obtained by LC-MS in the selected ion monitoring mode. For unambiguous identification of alkyl methylphosphonic acids, fragment ions were produced by in-source collision induced dissociation (CID), and then exact mass measurement of CID fragment ions was performed. The feasibility of applying this technique for detecting these compounds in spiked environmental waters and soils was demonstrated.