Part 1: Tracing Russian VX to its synthetic routes by multivariate statistics of chemical attribution signatures

Unveiling Impurity Profiling of Synthetic Pathways of Organophosphorus Chlorpyrifos Through LC-HRMS Metabolomics-Based Approaches

Sourcing in chemical forensic science refers to the attribution of a sample to a specific source using a characteristic signature. It relies on the identification of chemical attribution signatures (CAS), including chemical markers such as residual synthetic precursors, impurities, reaction by-products and degradation products, or even metabolites. Undertaking CAS for chemical threat agents (CTA) can be used to provide an evidentiary link between the use of a given chemical and its precursor(s) to support forensic investigations. Organophosphorus compounds, a class of nerve agents, can be produced by different, more or less complex synthesis routes that can lead to specific CAS. Chlorpyrifos (CPF), an organophosphorus pesticide, was selected as model compound. To assess the specificity of impurity markers originated from a chemical synthesis, untargeted fingerprints of crude CPF from different synthesis pathways were analyzed as a first use-case using metabolomics-based trace discovery strategies. Seven different CPF synthesis routes were considered, and their crude mixtures were analyzed with a minimal sample preparation. Analyses were performed on a trapped ion mobility spectrometry (TIMS) coupled to liquid chromatography (LC) and high-resolution mass spectrometry (HRMS). Chemometrics analyses were conducted with multivariate methods to extract discriminating features (i.e., relevant impurities), annotate, and identify them. Then, unknown samples were analyzed in blind conditions without any information of the synthesis pathway employed. The aim is to validate the methodology seeking some discriminating impurities identified in the first section to attribute and classify them according to the synthesis route.

75 years of forensic profiling: A critical review

The interest in characterization of drugs abused started in 1948 with the aim of determining the origin of opium. After 75 years there is still a great interest in this approach, called geo-profiling, chemical or forensic profiling in the following decades. Recently chemical attribution signatures (CAS) were proposed by the authors who studied "synthesis precursors and byproducts, impurities, degradation products, and metabolites in various biological matrices" of fentanyl. Forensic profiling evolved during these decades: new analytical approaches were tested and it was applied to more and more products, which threaten the health and security of citizens worldwide. In substances of natural origins (e.g. opium, cannabis and cocaine), it is possible to exploit the great variability of both elements and organic chemical compounds and to study chemical compounds such as reagents and solvents, by-products, and cutting agents used in the production chain. Profiles can be used to classify products from different seizures into groups of similar samples (tactical intelligence) or to determine the origin of samples (strategic intelligence). Chromatographic approaches coupled to mass spectrometry are very common to determine organic profiles, while elemental profiles are obtained by nuclear activation analysis, inductively coupled plasma mass spectrometry or ion beam analysis. A very important role in the field is played by isotope ratio analysis. Approaches to obtain forensic profiles are available also for chemical warfare agents, explosives, illegal medicines, doping agents, supplements, food. Chemometrics can be particularly useful to establish the authenticity of products and for the interpretation of large amount of forensic data. The future of forensic profiling is a challenge for forensic sciences. Organized crime is involved in the manufacturing of a large number of illegal products and forensic profiling is a very powerful tool to support the health of citizens and the administration of justice worldwide.

Use of carbonyldiimidazole as a derivatization agent for the detection of pinacolyl alcohol, a forensic marker for Soman, by EI-GC-MS and LC-HRMS in official OPCW proficiency test matrices

Pinacolyl alcohol (PA), a key forensic marker for the nerve agent Soman (GD), is a particularly difficult analyte to detect by various analytical methods. In this work, we have explored the reaction between PA and 1,1'-carbonyldiimidazole (CDI) to yield pinacolyl 1H-imidazole-1-carboxylate (PIC), a product that can be conveniently detected by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Regarding its GC-MS profile, this new carbamate derivative of PA possesses favorable chromatographic features such as a sharp peak and a longer retention time (RT = 16.62 min) relative to PA (broad peak and short retention time, RT = 4.1 min). The derivative can also be detected by LC-HRMS, providing an avenue for the analysis of this chemical using this technique where PA is virtually undetectable unless present in large concentrations. From a forensic science standpoint, detection of this low molecular weight alcohol signals the past or latent presence of the nerve agent Soman (GD) in a given matrix (i.e., environmental or biological). The efficiency of the protocol was tested separately in the analysis and detection of PA by EI-GC-MS and LC-HRMS when present at a 10 μg/mL in a soil matrix featured in the 44th PT and in a glycerol-rich liquid matrix featured in the 48th Official Organization for the Prohibition of Chemical Weapons (OPCW) Proficiency Test when present at a 5 μg/mL concentration. In both scenarios, PA was successfully transformed into PIC, establishing the protocol as an additional tool for the analysis of this unnatural and unique nerve agent marker by GC-MS and LC-HRMS.

Application of chemical attribution in matching OPNAs-exposed biological samples with exposure sources- based on the impurity profiles via GC × GC-TOFMS analysis

Chemical attribution is a vital tool to attribute chemicals or related materials to their origins in chemical forensics via various chemometric methods. Current progress related to organophosphorus nerve agents (OPNAs) has mainly focused on the attribution of chemical sources and synthetic pathways. It has not yet been applied in matching exposed biological samples to their sources. This work used chemical attribution to explore organic impurity profiles in biological samples exposed to various OPNAs. Chemical attribution was first used to identify the exposure source of biological samples based on the full-scan data via comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometer (GC × GC-TOFMS). Taking peak area as the only variable, it can quickly match exposed samples to their sources by applying unsupervised or supervised models, screen difference compounds via one-way ANOVA or t-tests, and then identify valuable impurities that can distinguish different types of exposed samples. To further obtain the impurity profile only applicable to a certain weapon' samples, the irrelevant components were removed via conventional methods. The findings showed there were 53 impurities that can promote distinguishing six groups of OPNA exposed samples, as well as 42 components that can be used as valuable impurities to distinguish class G and class V samples. These were all unique impurities that appear in a certain weapon' samples. The outcomes can be a reference for tracing the source for OPNA-exposed samples, which was beneficial to the further development in source matching of forensic samples. Moreover, the chemical attribution for impurity profiles in biological samples after weapons exposure may inspire research into the characteristics of impurity profile in biological samples as well as practical applications of chemical attribution for OPNA-exposed samples, that may expand potential biomarkers and break the limits of existing markers in the future.

Gas chromatography tandem mass spectrometric analysis of alkylphosphonofluoridic acids as verification targets of nerve agents

Alkylphosphonofluoridic Acids (APFA) are the major thermal degradation products of G- and A-series nerve agents and thus play a vital role in the verification analysis of Chemical Weapons Convention. Present study focuses on the development of sample clean-up, derivatization procedures and gas chromatography tandem mass spectrometric analysis of APFA in aqueous samples. APFA were found to be much more delicate than the corresponding alkylphosphonic acids and thus required subtle optimizations. Retention of analytes on silica and polymer-based anion exchangers followed by elution under alkaline conditions yielded best recoveries. Elution under acidic conditions led to partial or complete degradation of the analytes to alkylphosphonic acids. Silylation reactions, particularly with MTBSTFA were found the best in terms of chromatographic responses and resolution of the derivative peaks. Methylations with diazomethane, which requires acidic reaction media, failed to produce desired yields of the derivatives. Under optimized conditions, the analytes produced the recoveries ranging from 76.9 to 94.5% with RSD ≤9.2%. The best LOD's in the tandem mass spectrometric analysis ranged from 13 to 56 ng/ml. The applicability of the method was tested by spiking the analytes in the retained aqueous samples received for the 52nd proficiency test conducted by the Organization for the Prohibition of Chemical Weapons (OPCW).

Chemical, Physical, and Toxicological Properties of V-Agents

V-agents are exceedingly toxic organophosphate nerve agents. The most widely known V-agents are the phosphonylated thiocholines VX and VR. Nonetheless, other V-subclasses have been synthesized. Here, a holistic overview of V-agents is provided, where these compounds have been categorized based on their structures to facilitate their study. A total of seven subclasses of V-agents have been identified, including phospho(n/r)ylated selenocholines and non-sulfur-containing agents, such as VP and EA-1576 (EA: Edgewood Arsenal). Certain V-agents have been designed through the conversion of phosphorylated pesticides to their respective phosphonylated analogs, such as EA-1576 derived from mevinphos. Further, this review provides a description of their production, physical properties, toxicity, and stability during storage. Importantly, V-agents constitute a percutaneous hazard, while their high stability ensures the contamination of the exposed area for weeks. The danger of V-agents was highlighted in the 1968 VX accident in Utah. Until now, VX has been used in limited cases of terrorist attacks and assassinations, but there is an increased concern about potential terrorist production and use. For this reason, studying the chemistry of VX and other less-studied V-agents is important to understand their properties and develop potential countermeasures.

Forensic analysis of the deuterium/hydrogen isotopic ratios of the nerve agent sarin, its reaction by-product diisopropyl methylphosphonate and their precursors by 2H SNIF-NMR

The Deuterium/Hydrogen (D/H) isotope ratios of sarin (5), diisopropyl methylphosphonate (3) and their precursors Isopropanol (1), methylphosphonic acid dichloride (2) and methylphosphonic acid difluoride (4) were measured by the ²H SNIF-NMR technique. The D/H isotope ratios of 1 show a large variation. It is shown, that the formation of 3 by reaction of 1 with 2, the fluorination of 2 to form 4 and the reaction of 4 with 1 to form 5, the D/H isotope ratios of the methyl and isopropyl moieties in 3, 4 and 5 are not significantly changed compared to 1 and 2.

Benzyl trichloroacetimidates as derivatizing agents for phosphonic acids related to nerve agents by EI-GC-MS during OPCW proficiency test scenarios

The use of benzyl trichloroacetimidates for the benzylation of phosphonic acid nerve agent markers under neutral, basic, and slightly acidic conditions is presented. The benzyl-derived phosphonic acids were detected and analyzed by Electron Ionization Gas Chromatography-Mass Spectrometry (EI-GC-MS). The phosphonic acids used in this work included ethyl-, cyclohexyl- and pinacolyl methylphosphonic acid, first pass hydrolysis products from the nerve agents ethyl N-2-diisopropylaminoethyl methylphosphonothiolate (VX), cyclosarin (GF) and soman (GD) respectively. Optimization of reaction parameters for the benzylation included reaction time and solvent, temperature and the effect of the absence or presence of catalytic acid. The optimized conditions for the derivatization of the phosphonic acids specifically for their benzylation, included neutral as well as catalytic acid (< 5 mol%) and benzyl 2,2,2-trichloroacetimidate in excess coupled to heating the mixture to 60 °C in acetonitrile for 4 h. While the neutral conditions for the method proved to be efficient for the preparation of the p-methoxybenzyl esters of the phosphonic acids, the acid-catalyzed process appeared to provide much lower yields of the products relative to its benzyl counterpart. The method's efficiency was tested in the successful derivatization and identification of pinacolyl methylphosphonic acid (PMPA) as its benzyl ester when present at a concentration of ~ 5 μg/g in a soil matrix featured in the Organisation for the Prohibition of Chemical Weapons (OPCW) 44th proficiency test (PT). Additionally, the protocol was used in the detection and identification of PMPA when spiked at ~ 10 μg/mL concentration in a fatty acid-rich liquid matrix featured during the 38^th OPCW-PT. The benzyl derivative of PMPA was partially corroborated with the instrument's internal NIST spectral library and the OPCW central analytical database (OCAD v.21_2019) but unambiguously identified through comparison with a synthesized authentic standard. The method's MDL (LOD) values for the benzyl and the p-methoxybenzyl pinacolyl methylphosphonic acids were determined to be 35 and 63 ng/mL respectively, while the method's Limit of Quantitation (LOQ) was determined to be 104 and 189 ng/mL respectively in the OPCW-PT soil matrix evaluated.

Retrospective detection for V-type OPNAs exposure via phosphonylation and disulfide adducts in albumin

Organophosphorus nerve agents (OPNAs) that damage the central nervous system by inhibiting acetylcholinesterase activity, pose severe threats to human health and life security. Reliable biomarkers that quickly and accurately detect OPNAs exposure are urgently needed to help diagnose quickly and treat in time. Albumins that covalently bind to OPNAs could serve as important targets for retrospective verification of OPNAs exposure. The goal of this study is to explore the potential biomarkers in albumins with high reactivity and good stability and expand the group of potential biomarkers in different species for detecting the exposure of V-type OPNAs including O-ethyl S-(2-(diisopropylamino)ethyl) methylphosphonothioate (VX), O-isobutyl S-(2(diethylamino)ethyl) methylphosphonothioate (VR), and O-butyl S-(2-(diethylamino)ethyl) methylphosphonothioate (Vs). Taking human serum albumin (HSA), bovine serum albumin (BSA) and rabbit serum albumin (RSA) as the research objectives, multiple active sites including phosphonylation and disulfide adduct sites were observed in albumins from different species. Numerous phosphonylation sites labeled by all agents in one type of albumin were found. Among the different species, four shared phosphonylation sites with high reactivity include K499, K549, K249, and Y108. In addition, Y108 on ETY*GEMADCCAK, Y287 on Y*ICENQDSISSK, Y377 on TY*ETTLEK and Y164 on YLY*EIAR in HSA were stably phosphonylated by all agents in gradient concentration, making them stable and suitable potential biomarkers for V-type OPNAs exposure. Notably, Y108 on ETY*GEMADCCAK in HSA, on DTY*GDVADCCEK in RSA, and on ETY*GDMADCCEK in BSA were highly reactive to all V-type agents, regardless of species. It was also successfully labeled in HSA exposed to class V agents in gradient concentration. Y108 is expected to be used to screen and identify the exposure of V-type agents in the retrospective research. Disulfide adducts sites, consisted of four sites in HSA and two sites in BSA were also successfully labeled by V-type agents, and characteristic ion fragments from these disulfide adducts were also identified by secondary mass spectrometry. Molecular simulation of the stably modified sites were conducted to discover the promoting factors of covalent adduct formation, which help further clarify formation mechanism of albumin adducts at active sites.

Chemical forensic profiling and attribution signature determination of sarin nerve agent using GC-MS, LC-MS and NMR

Sarin is a highly toxic nerve agent classified by the Chemical Weapon Convention as a Schedule 1 chemical with no use other than to kill or injure. Moreover, in recent times, chemical warfare agents have been deployed against both military and civilian populations. Chemical warfare agents always contain minor impurities that can provide important chemical attribution signatures (CAS) that can aid in forensic investigations. In order to understand the trace molecular composition of sarin, various analytical approaches including GC-MS, LC-MS and NMR were used to determine the chemical markers of a set of sarin samples. Precursor materials were studied and the full characterisation of a synthetic process was undertaken in order to provide new insights into potential chemical attribution signatures for this agent. Several compounds that were identified in the precursor were also found in the sarin samples linking it to its method of preparation. The identification of these CAS contributes critical information about a synthetic route to sarin, and has potential for translation to related nerve agents.

Source Attribution of the Chemical Warfare Agent Soman Using Position-Specific Isotope Analysis by 2H NMR Spectroscopy: From Precursor to Degradation Product

Position-specific isotope analysis (PSIA) by NMR spectroscopy is a technique that provides quantitative isotopic values for every site—a so-called isotopic fingerprint—of a compound of interest. The isotopic fingerprint can be used to link samples with a common origin or to attribute a synthetic chemical to its precursor source. Despite PSIA by NMR being a powerful tool in chemical forensics, it has not yet been applied on chemical warfare agents (CWAs). In this study, different batches of the CWA Soman were synthesized from three distinctive pinacolyl alcohols (PinOHs). Prior to NMR analysis, the Soman samples were hydrolyzed to the less toxic pinacolyl methylphosphonate (PMP), which is a common degradation product. The PinOHs and PMPs were applied to PSIA by ²H NMR experiments to measure the isotopic distribution of naturally abundant ²H within the pinacolyl moiety. By normalizing the ²H NMR peak areas, we show that the different PinOHs have unique intramolecular isotopic distributions. This normalization method makes the study independent of references and sample concentration. We also demonstrate, for the first time, that the isotopic fingerprint retrieved from PSIA by NMR remains stable during the production and degradation of the CWA. By comparing the intramolecular isotopic profiles of the precursor PinOH with the degradation product PMP, it is possible to attribute them to each other.

Forensic signatures of a chemical weapon precursor DMPADC for determination of a synthetic route

Chemical forensics has been widely recognized as an important tool to investigate alleged use of chemical weapons and/or to identify the illicit production of chemical warfare agents. This paper describes the use of gas chromatography and mass spectrometry (GC-MS) to determine chemical attribution signatures (CAS) N,N-dimethylphosphoramidic dichloride (DMPADC), a key precursor of tabun, for tracking the production of tabun. Synthetic samples were identified and classified by using GC-MS and chemometrics. Analysis samples (n = 27) were collected from three synthetic DMPADC routes; 20 potential CAS were identified, and the structures of five CAS were assigned. Principal component analysis (PCA) was performed to summarize the distribution trend of the samples and to check for the presence of outliers. A Partial least squares discriminant analysis (PLSDA) model was established to discriminate and classify the synthetic samples. The proposed model in this paper has high predictive ability, and the test set samples can be correctly categorized.

Analysis of Organophosphorus-Based Nerve Agent Degradation Products by Gas Chromatography-Mass Spectrometry (GC-MS): Current Derivatization Reactions in the Analytical Chemist's Toolbox

The field of gas chromatography-mass spectrometry (GC-MS) in the analysis of chemical warfare agents (CWAs), specifically those involving the organophosphorus-based nerve agents (OPNAs), is a continually evolving and dynamic area of research. The ever-present interest in this field within analytical chemistry is driven by the constant threat posed by these lethal CWAs, highlighted by their use during the Tokyo subway attack in 1995, their deliberate use on civilians in Syria in 2013, and their use in the poisoning of Sergei and Yulia Skripal in Great Britain in 2018 and Alexei Navalny in 2020. These events coupled with their potential for mass destruction only serve to stress the importance of developing methods for their rapid and unambiguous detection. Although the direct detection of OPNAs is possible by GC-MS, in most instances, the analytical chemist must rely on the detection of the products arising from their degradation. To this end, derivatization reactions mainly in the form of silylations and alkylations employing a vast array of reagents have played a pivotal role in the efficient detection of these products that can be used retrospectively to identify the original OPNA.

Gas Chromatography-Mass Spectrometry Analysis of Synthetic Opioids Belonging to the Fentanyl Class: A Review

The rising number of deaths caused by fentanyl overdosing in the US due to the overwhelming illicit use of this synthetic opioid has started a global campaign to develop efficient ways to control its production and distribution as well as discovering efficient antidotes to mitigate its lethal effects. Another important vein of focused research established by various agencies lies in the development of efficient and practical protocols for the detection of this opioid and analogs thereof in various matrices, whether environmental or biological in nature, particularly in the field of gas chromatography-mass spectrometry (GC-MS). The following review will cover the literature dealing with the detection and identification of synthetic opioids belonging to the fentanyl class by GC-MS means and hyphenated versions of the technique. Detailed descriptions will be given for the GC-MS methods employed for the analysis of the opioid, starting with the nature of the extraction protocol employed prior to analysis to the actual findings presented by the cited reports. Great effort has gone into describing the methods involved in each paper in a detailed manner and these have been compiled by year in tables at the end of each section for the reader's convenience. Lastly, the review will end with concluding remarks about the state of GC-MS analysis with regards to these powerful opioids and what lies ahead for this analytical field.

Mass spectrometric analysis of adducts of sulfur mustard analogues to human plasma proteins: approach towards chemical provenancing in biomedical samples

The primary aim of this study was to identify biomarkers of exposure to some so-called Schedule 1 sulfur mustard (HD) analogues, in order to facilitate and expedite their retrospective analysis in case of alleged use of such compounds. Since these HD analogues can be regarded as model compounds for possible impurities of HD formed during synthesis processes, the secondary aim was to explore to which extent these biomarkers can be used for chemical provenancing of HD in case biomedical samples are available. While the use of chemical attribution signatures (CAS) for neat chemicals or for environmental samples has been addressed quite frequently, the use of CAS for investigating impurities in biomedical samples has been addressed only scarcely. Human plasma was exposed to each of the five HD analogues. After pronase or proteinase K digestion of precipitated protein and sample work-up, the histidine (His) and tripeptide (CPF) adducts to proteins were analyzed, respectively. Adducts of the analogues could still be unambiguously identified next to the main HD adducts in processed plasma samples after exposure to HD mixed with each of the analogues, at a 1% level relative to HD. In conclusion, we have identified plasma protein adducts of a number of HD analogues, which can be used as biomarkers to assess an exposure to these Schedule 1 chemicals. We have shown that adducts of these analogues can still be analyzed after work-up of plasma samples which had been exposed to these analogues in a mixture with HD, supporting the hypothesis that biomedical sample analysis might be useful for chemical provenancing.

Investigating the chemical impurity profiles of fentanyl preparations and precursors to identify chemical attribution signatures for synthetic method attribution

From an analytical chemistry standpoint, determining the chemical attribution signatures (CAS) of synthetic reaction mixtures is an impurity profiling exercise. Identifying and understanding the impurity profile and CAS of these chemical agents would allow them to be exploited for chemical forensic information, such as how a particular chemical agent was synthesised. Being able to determine the synthetic route used to make a chemical agent allows for the possibility of batches of the agent, and individual incidents using that agent, to be forensically linked. This information is of particular benefit to agencies investigating the nefarious and illicit use of chemical agents. One such chemical agent of interest to law enforcement and national security agencies is fentanyl. In this study two acylation methods for the final step of fentanyl production, herein termed the Janssen and Siegfried methods, were investigated by liquid chromatography- high resolution mass spectrometry (LC-HRMS) and multivariate statistical analysis (MVA). From these data, fifty-five chemical impurities were identified. Of these, ten were specific CAS for the Janssen method, and five for the Siegfried method. Additionally, analytical data from four different literature methods for production of the fentanyl precursor 4-anilino-N-phenethylpiperidine (ANPP), were compared to the results obtained from the method of production (Valdez) used in this study. Comparison of the LC-HRMS data for these five methods allowed for four Valdez specific impurities to be identified. These may be useful CAS for the Valdez method of ANPP production.

Adduct of the blistering warfare agent sesquimustard with human serum albumin and its mass spectrometric identification for biomedical verification of exposure

Apart from the well-known sulfur mustard (SM), additional sulfur-containing blistering chemical warfare agents exist. Sesquimustard (Q) is one of them and five times more blistering than SM. It is a common impurity in mustard mixtures and regularly found in old munitions but can also be used in pure form. Compared to the extensive literature on SM, very little experimental data is available on Q and no protein biomarkers of exposure have been reported. We herein report for the first time the adduct of Q with the nucleophilic Cys34 residue of human serum albumin (HSA) formed in vitro and introduce two novel bioanalytical procedures for detection. After proteolysis of this HSA adduct catalyzed either by pronase or by proteinase K, two biomarkers were identified by high-resolution tandem mass spectrometry (MS/HR MS), namely a dipeptide and a tripeptide, both alkylated at their Cys residue, which we refer to as HETETE-CP and HETETE-CPF. HETETE represents the Q-derived thio-alkyl moiety bearing a terminal hydroxyl group: "hydroxyethylthioethylthioethyl." Targeting both peptide markers from plasma, a micro liquid chromatography-electrospray ionization tandem mass spectrometry method working in the selected reaction monitoring mode (μLC-ESI MS/MS SRM) was developed and validated as well suited for the verification of exposure to Q. Fulfilling the quality criteria defined by the Organisation for the Prohibition of Chemical Weapons, the novel methods enable the detection of exposure to Q alone or in mixtures with SM. We further report on the relative reactivity of Q compared to SM. Based on experiments making use of partially deuterated Q as the alkylating agent, we rule out a major role for six-membered ring sulfonium ions as relevant reactive species in the alkylation of Cys34. Furthermore, the results of molecular dynamics simulations are indicative that the protein environment around Cys34 allows adduct formation with elongated but not bulky molecules such as Q, and identify important hydrogen bonding interactions and hydrophobic contacts. Graphical abstract.

Methylation protocol for the retrospective detection of isopropyl-, pinacolyl- and cyclohexylmethylphosphonic acids, indicative markers for the nerve agents sarin, soman and cyclosarin, at low levels in soils using EI-GC-MS

A practical and efficient protocol for the derivatization and detection by GC-EI-MS of isopropyl-, pinacolyl- and cyclohexylmethylphosphonic acids, key diagnostic degradation products of the nerve agents sarin, soman and cyclosarin respectively, in six different types of soil matrices is presented. The method involves the in situ conversion of the phosphonic acids to their respective methyl esters using trimethyloxonium tetrafluoroborate when present in the soils at low levels (10 μg g^-1) without any prior extractions or soil preparation. The soils employed in our study were Nebraska EPA soil, Georgia soil, silt, Virginia type A soil, regular sand and Ottawa sand and were chosen for their vast differences in composition and physical features. Appealing attributes of the protocol include its rapidity (t < 30 min), mildness (ambient temperature), and practicality that includes the production of the phosphonic methyl esters that can be easily detected by GC-EI-MS and corroborated with the instrument's internal NIST spectral library or the Organisation for the Prohibition of Chemical Weapons (OPCW) central analytical database (OCAD v.21_2019). The overall efficacy of the protocol was then tested on a soil sample featured in the 44th OPCW PT that our laboratory participated in. After preparing the soil so as to give pinacolyl methylphosphonic acid at a 5 μg g^-1 concentration, the acid was successfully methylated and detected by GC-EI-MS. The protocol's performance mirrors that of the universally employed diazomethane protocol but accomplishes this without any of the explosive hazards and time consuming reagent preparation commonly associated with it.

Source attribution profiling of five species of Amanita mushrooms from four European countries by high resolution liquid chromatography-mass spectrometry combined with multivariate statistical analysis and DNA-barcoding

Source attribution profiling of five species of Amanita mushrooms from four European countries was performed using Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS) combined with multivariate statistical analysis. Initially, species determination was carried out morphologically and was verified by DNA-analysis. This data was then combined with chemical profiling, generated from LC-HRMS full scan analysis. The untargeted data was processed and the 720 most abundant peaks in the LC-HRMS chromatogram were used to build a multivariate PLS-DA model. The two independent methods for species determination showed 100% correlation, indicating the potential use of chemical profiling as a supporting technique to genetic methods. When specimens of one species were studied, significant variation related to the region of growth was found. The potential of the geo-positioning was shown for A. phalloides from Sweden, Denmark and UK and A. virosa from Sweden and Denmark. Additionally, A. virosa specimens could be attributed to three geographically different regions of Sweden.

Part 3: Solid phase extraction of Russian VX and its chemical attribution signatures in food matrices and their detection by GC-MS and LC-MS

Chemical attribution signatures indicative of O-isobutyl S-(2-diethylaminoethyl) methylphosphonothioate (Russian VX) synthetic routes were investigated in spiked food samples. Attribution signatures were identified using a multifaceted approach: Russian VX was synthesized using six synthetic routes and the chemical attribution signatures identified by GC-MS and LC-MS. Three synthetic routes were then down selected and spiked into complex matrices: bottled water, baby food, milk, liquid eggs, and hot dogs. Sampling and extraction methodologies were developed for these materials and used to isolate the attribution signatures and Russian VX from each matrix. Recoveries greater than 60% were achieved for most signatures in all matrices; some signatures provided recoveries greater than 100%, indicating some degradation during sample preparation. A chemometric model was then developed and validated with the concatenated data from GC-MS and LC-MS analyses of the signatures; the classification results of the model were > 75% for all samples. This work is part three of a three-part series in this issue of the United States-Sweden collaborative efforts towards the understanding of the chemical attribution signatures of Russian VX in crude materials and in food matrices.

Part 2: Forensic attribution profiling of Russian VX in food using liquid chromatography-mass spectrometry

This work is part two of a three-part series in this issue of a Sweden-United States collaborative effort towards the understanding of the chemical attribution signatures of Russian VX (VR) in synthesized samples and complex food matrices. In this study, we describe the sourcing of VR present in food based on chemical analysis of attribution signatures by liquid chromatography-tandem mass spectrometry (LC-MS/MS) combined with multivariate data analysis. Analytical data was acquired from seven different foods spiked with VR batches that were synthesized via six different routes in two separate laboratories. The synthesis products were spiked at a lethal dose into seven food matrices: water, orange juice, apple purée, baby food, pea purée, liquid eggs and hot dog. After acetonitrile sample extraction, the samples were analyzed by LC-MS/MS operated in MRM mode. A multivariate statistical calibration model was built on the chemical attribution profiles from 118 VR spiked food samples. Using the model, an external test-set of the six synthesis routes employed for VR production was correctly identified with no observable major impact of the food matrices to the classification. The overall performance of the statistical models was found to be exceptional (94%) for the test set samples retrospectively classified to their synthesis routes.