Verification Of Chemical Weapons Convention Research Articles

Extraction of Novichoks from aqueous samples for verification analysis of Chemical Weapons Convention

ABSTRACT The study was undertaken with the objective of evaluating the different procedures for the extraction of the Novichok class of chemicals from aqueous samples for the verification of Chemical Weapons Convention (CWC). These classes of chemicals are recently added to the scheduled list of CWC, which necessitates the optimisation of analytical protocols for their verification analyses in different environmental samples. Three analytes, namely N-(1-(diethylamino)ethylidene)-P-methylphosphonamidic fluoride (A230), methyl N-(1-(diethylamino)ethylidene)phosphoramidofluoridate (A232) and ethyl N-(1-(diethylamino)ethylidene)phosphoramidofluoridate (A234), were taken as representative chemicals in aqueous samples and extracted with established protocols, such as liquid–liquid extraction (LLE), solid phase extraction (SPE), solid-supported liquid extraction (SLE) and liquid phase microextraction (LPME) techniques. The extraction efficacies were evaluated in terms of the recoveries of analytes as well as the removal of background interferences. Amongst the extraction techniques, SLE offered the least (43.2–66.7%) and LLE and SPE-HLB offered the best recoveries (79.1–92.9%) of the analytes with adequate sample clean-up. LPME techniques produced much better detection limits, going down to 7.6 ng/mL for A234. LPME methods were also found advantageous in terms of high enrichment factors, ease of operation, minimal waste generation and individual safety for handling the toxic chemicals.

Polyelectrolyte functionalized multi-walled carbon nanotubes as strong anion-exchange material for the extraction of acidic degradation products of nerve agents

Extraction, enrichment and gas chromatography mass spectrometric analysis of degradation products of nerve agents from water is of significant importance for verification of Chemical Weapons Convention (CWC) and gathering forensic evidence of use of nerve agents. Multi-walled carbon nanotubes (MWCNTs) were non-covalently functionalized with poly(diallyldimethylammonium chloride) (PDDA) to afford the cationic functionalized nano-tubes, which were used as solid-phase anionic-exchanger sorbents to extract the acidic degradation products of nerve agents from water. Extraction efficiencies of MWCNTs-PDDA were compared with those of mixed mode anion-exchange (HLB) and silica based strong anion-exchange (Si-SAX) cartridges. Optimized extraction parameters included MWCNTs-PDDA 12 mg, washing solvent 5 mL water and eluting solvent 3 mL of 0.1M aqueous HCl followed by 3 mL methanol. At 1 ng mL(-1) spiking concentration of mono- and di-basic phosphonic acids, MWCNTs-PDDA exhibited higher extraction efficiencies in comparison to Si-SAX and HLB. The limits of detection were achieved down to 0.05 and 0.11 ng mL(-1) in selected ion and full scan monitoring mode respectively; and limits of quantification in selected ion monitoring mode were achieved down to 0.21 ng mL(-1).

The convergence of biology and chemistry: Implications for arms control verification

As biological and chemical production technologies grow increasingly interrelated, the implications of this convergence for preventing the spread of biological and chemical weapons are becoming more serious. The author writes that the routine verification regime of the Chemical Weapons Convention (CWC) does not cover biologically mediated production processes or the synthesis of most natural toxins by chemical means—gaps, he says, that are likely to expand as these technologies advance. To address the implications of convergence for biological and chemical disarmament, CWC member states should enhance the treaty’s verification measures. The author suggests that a panel of experts should examine the technical feasibility and cost-effectiveness of using biotechnological methods to produce classical chemical warfare agents; that CWC parties should increase the total number of inspections of declared chemical industry facilities that can be conducted per year in a member state; and that the scope of CWC verification should be broadened to cover production by chemical or biological means of natural peptides and structurally related molecules, some of which are highly toxic. Although efforts to update the CWC verification regime will face political resistance, he writes, it would be short-sighted to ignore this problem until determined cheaters start using undeclared biotechnology plants to manufacture chemical warfare agents, or exploit the chemical synthesis of bioactive peptides to develop a new generation of biochemical warfare agents.

Gas chromatography-mass spectrometric analysis of trimethylsilyl derivatives of toxic hydrolyzed products of nerve agent VX and its analogues for verification of Chemical Weapons Convention

The formation of trimethylsilyl (TMS) derivative of hydrolyzed product of nerve agent VX, namely S-2-(N,N-diisopropylaminoethyl) methylphosphonothiolate (EA-2192), was reported to be hampered due to its zwiterionic character. Contrary to this assumption, we have synthesized and analyzed the TMS derivative of EA-2192 and its analogues. Initially, the problem of non-detectability in GC-MS analysis was found to be due to their condensation followed by decomposition on GC column. An optimized temperature program, starting from 175 °C column temperature, favours partitioning of TMS derivatives of EA-2192 and its analogues into mobile phase, which facilitates their detection. It reduces their on-column condensation and decomposition. Excellent reproducibility (<1% RSD) of TMS derivatives of S-2-(N,N-dialkylaminoethyl) alkylphosphonothiolates was achieved by GC-MS analysis with temperature program of 175 °C (2 min)–10 °C min−1– 300 °C (5 min). Under the optimized conditions LODs ranged from 8–10 μg mL−1 for different analytes at a split ratio of 1 : 10.

Gas Chromatography Electron Ionization Mass Spectrometric Analysis of O-Alkyl Methylphosphinates for Verification of Chemical Weapons Convention

We describe the gas chromatography/mass spectrometric (GC/MS) analysis of O-alkyl methylphosphinates (AMPs), which are included in schedule 2B4 chemicals in the Chemical Weapons Convention (CWC). GC/MS analysis of variety of AMPs and their deuterated analogues revealed that their fragmentations were determined by alpha-cleavages, McLafferty +1 and hydrogen rearrangements. Based on the obtained electron ionization mass spectra of AMPs the fragmentation routes were rationalized, which were substantiated by the GC/MS analysis of deuterated analogues.

Enhanced detectability of fluorinated derivatives of N, N-dialkylamino alcohols and precursors of nitrogen mustards by gas chromatography coupled to Fourier transform infrared spectroscopy analysis for verification of chemical weapons convention

N, N-Dialkylamino alcohols, N-methyldiethanolamine, N-ethyldiethanolamine and triethanolamine are the precursors of VX type nerve agents and three different nitrogen mustards respectively. Their detection and identification is of paramount importance for verification analysis of chemical weapons convention. GC–FTIR is used as complimentary technique to GC–MS analysis for identification of these analytes. One constraint of GC–FTIR, its low sensitivity, was overcome by converting the analytes to their fluorinated derivatives. Owing to high absorptivity in IR region, these derivatives facilitated their detection by GC–FTIR analysis. Derivatizing reagents having trimethylsilyl, trifluoroacyl and heptafluorobutyryl groups on imidazole moiety were screened. Derivatives formed there were analyzed by GC–FTIR quantitatively. Of these reagents studied, heptafluorobutyrylimidazole (HFBI) produced the greatest increase in sensitivity by GC–FTIR detection. 60–125 folds of sensitivity enhancement were observed for the analytes by HFBI derivatization. Absorbance due to various functional groups responsible for enhanced sensitivity were compared by determining their corresponding relative molar extinction coefficients ( ε ′ max ) considering uniform optical path length. The RSDs for intraday repeatability and interday reproducibility for various derivatives were 0.2–1.1% and 0.3–1.8%. Limit of detection (LOD) was achieved up to 10–15 ng and applicability of the method was tested with unknown samples obtained in international proficiency tests.

Application of cation-exchange solid-phase extraction for the analysis of amino alcohols from water and human plasma for verification of Chemical Weapons Convention

The analysis of nitrogen containing amino alcohols, which are the precursors and degradation products of nitrogen mustards and nerve agent VX, constitutes an important aspect for verifying the compliance to the CWC (Chemical Weapons Convention). This work devotes on the development of solid-phase extraction method using silica- and polymer-based SCX (strong cation-exchange) and MCX (mixed-mode strong cation-exchange) cartridges for N, N-dialkylaminoethane-2-ols and alkyl N, N-diethanolamines, from water. The extracted analytes were analyzed by GC–MS (gas chromatography–mass spectrometry) in the full scan and selected ion monitoring modes. The extraction efficiencies of SCX and MCX cartridges were compared, and results revealed that SCX performed better. Extraction parameters, such as loading capacity, extraction solvent, its volume, and washing solvent were optimized. Best recoveries were obtained using 2 mL methanol containing 10% NH 4OH and limits of detection could be achieved up to 5 × 10 −3 μg mL −1 in the selected ion monitoring mode and 0.01 μg mL −1 in full scan mode. The method was successfully employed for the detection and identification of amino alcohol present in water sample sent by Organization for Prohibition of Chemical Weapons (OPCW) in the official proficiency tests. The method was also applied to extract the analytes from human plasma. The SCX cartridge showed good recoveries of amino alcohols from human plasma after protein precipitation.

N,N′-Dichlorobis(2,4,6-trichlorophenyl)urea (CC-2): an Efficient Reagent for the Synthesis of Chemical Weapons Convention-Related Dialkyl-N,N-dialkylphosphoramidates from Dialkylphosphites

The present paper describes the one-pot synthesis of dialkyl N,N-dialkylphosphoramidates (DADAP) from dialkylphosphites and dialkylamines using N,N′-dichlorobis(2,4,6-trichlorophenyl)urea (CC-2) as chlorinating reagent. DADAP belong to the schedule 2.B.6 category of the Chemical Weapons Convention (CWC), as they are the important markers of the chemical warfare agent tabun and its analogues. The study was undertaken to develop the spectral database of DADAP for verification of CWC. The reported synthetic strategy can be adopted to rapidly synthesize several analogues of DADAP during official proficiency tests.

In situ derivatization hollow fiber mediated liquid phase microextraction of alkylphosphonic acids from water

Alkylphosphonic acids (APAs), particularly the methyl-, ethyl-, isopropyl- and n-propyl-phosphonic acids are important markers of extremely toxic nerve agents. Hence, their detection and identification is of vital importance to verification of chemical weapons convention (CWC). Verification analysis of CWC requires development of fast, reliable, simple and reproducible sample preparation methods of water and soil samples. Present investigation is focused on the optimization of alkylation of APAs in water with subsequent extraction of alkylated acids by hollow fiber liquid phase microextraction (HF-LPME). This simple and sensitive sample preparation of APAs from water offered better recoveries in comparison to conventionally used extraction technique. Under optimized conditions, the APAs were detected at the concentration of 0.5–0.75 μg/mL with S/N ratio ≥5, whereas the LODs for alkyl APAs (monobasic APAs) were achieved up to 0.1 μg/mL. The developed method was finally tested with water samples supplied in 19th official proficiency test conducted by the OPCW.

Applications of Deactivated GC Columns for Analysis of Nitrogen-Containing Chemicals Related to the Chemical Weapons Convention

Nitrogen-containing chemicals are one of the important families of compounds relevant to the purposes of the Chemical Weapons Convention (CWC). Several applications, using various injection modes, of new deactivated columns specially designed for basic compounds are presented. These columns prove remarkably well-suited to the gas chromatographic (GC) analysis of the chemicals of interest, even to underivatized amino-alcohols, whose analysis on conventional GC columns is often difficult and hindered by poor resolution and high detection limits. Such a deactivated phase can even replace the typical GC phases used for CWC verification purposes.

Electrospray ionisation mass spectral studies on hydrolysed products of sulfur mustards

Off-site detection of the hydrolysed products of sulfur mustards in aqueous samples is an important task in the verification of Chemical Weapons Convention (CWC)-related chemicals. The hydrolysed products of sulfur mustards are studied under positive and negative electrospray ionisation (ESI) conditions using an additive with a view to detecting them at trace levels. In the presence of cations (Li(+), Na(+), K(+) and NH(4) (+)), the positive ion ESI mass spectra of all the compounds include the corresponding cationised species; however, only the [M+NH(4)](+) ions form [M+H](+) ions upon decomposition. The tandem mass (MS/MS) spectra of [M+H](+) ions from all the hydrolysed products of the sulfur mustard homologues were distinct and allowed these compounds to be characterised unambiguously. Similarly, the negative ion ESI mass spectra of all the compounds show prominent adducts with added anions (F(-), Cl(-), Br(-), and I(-)), but the [M-H](-) ion can only be generated by decomposition of an [M+F](-) ion. The MS/MS spectra of the [M-H](-) ions from all the compounds result in a common product ion at m/z 77. A precursor ion scan of m/z 77 is shown to be useful in the rapid screening of these compounds in aqueous samples at trace levels, even in the presence of complex masking agents, without the use of time-consuming sample preparation and chromatography steps. An MS/MS method developed to measure the detection limits of the hydrolysed products of sulfur mustards found these to be in the range of 10-500 ppb.

On-matrix derivatisation–extraction of precursors of nitrogen- and sulfur-mustards for verification of chemical weapons convention

Development and refinement of sample preparation protocols for retrospective detection and identification of chemical warfare agents (CWAs) and their markers is of paramount importance from verification point of view of chemical weapons convention (CWC). Precursors of nitrogen- and sulfur-mustards (NMPs and SMPs) are polar adsorptive markers of vesicant class of CWAs. Their detection in a given environmental sample may imply past contamination with mustards. For the efficient extraction of NMPs and SMPs from soil, on-matrix derivatisation–extraction (OMDEX) method was developed and optimized. The method involved trifluoroacetylation of analytes on soil itself, followed by extraction with suitable solvent. The extracted samples were analyzed by gas chromatography–mass spectrometry (GC–MS). This virtually single-step sample preparation offered better recoveries of NMPs and SMPs in comparison to conventionally used extraction, evaporation and derivatisation. The best recoveries of analytes were obtained with acetonitrile by OMDEX method. Dynamic linearity range of trifluoroacetylated (TFA) derivatives of NMPs and SMPs was 1–12 μg/L in GC–MS analysis in SIM mode. Repeatability and reproducibility of this technique containing 5 and 10 μg analytes/gm soil was <3.3% and <4.6%, respectively. OMDEX technique was finally applied for the detection of TFA derivatives of NMPs in the soil sample supplied in 16th official proficiency test conducted by OPCW in October 2004.

Gas chromatography–mass spectrometry analysis of trifluoroacetyl derivatives of precursors of nitrogen and sulfur mustards for verification of chemical weapons convention

Trifluoroacetylation reactions were optimized for gas chromatography–mass spectrometric (GC–MS) analysis of precursors of nitrogen and sulfur mustards using newly developed N-trifluoroacetylbenzimidazole (TFABI) and known N-trifluoroacetylimidazole (TFAI) and N-trifluoroacetylbenzotriazole (TFABT) reagents. TFAI and TFABI gave the best results in terms of yields and reaction time. Trifluoroacetyl derivatives showed clean total ion chromatograms in GC–MS analysis than trimethylsilyl (TMS) derivatives. The negative ion chemical ionization analysis of these derivatives gave pseudo molecular weight information, with low limit of detection.