Robin M. Black

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, sulphur mustard and their degradation products.

Samples of clothing, grave debris, soil and munition fragments, collected from the Kurdish village of Birjinni, were analysed by GC-MS with selected ion monitoring (SIM) for traces of chemical warfare agents and their degradation products. Positive analyses were confirmed, where possible, by full scan mass spectra, or at low concentrations by additional GC-MS-SIM analysis using chemical ionisation, by higher resolution GC-MS-SIM, and by GC-tandem mass spectrometry using multiple reaction monitoring. Sulphur mustard and/or thiodiglycol were detected in six soil samples; isopropyl methylphosphonic acid and methylphosphonic acid, the hydrolysis products of the nerve agent sarin, were detected in six different soil samples. Trace amounts of intact sarin were detected on a painted metal fragment associated with one of these soil samples. The results demonstrate the application of different GC-MS and GC-MS-MS techniques to the unequivocal identification of chemical warfare agent residues in the environment at concentrations ranging from low ppb to ppm (w/w). They also provide the first documented unequivocal identification of nerve agent residues in environmental samples collected after a chemical attack.

Derivatisation reactions in the chromatographic analysis of chemical warfare agents and their degradation products

The analysis of chemical warfare agents and their degradation products is an important component of verification of compliance with the Chemical Weapons Convention. Gas and liquid chromatography, particularly combined with mass spectrometry, are the major techniques used to detect and identify chemicals of concern to the Convention. The more polar analytes, and some of the more reactive or highly volatile agents, are usually derivatised to facilitate chromatography, and to impart properties beneficial for detection. This review focuses on derivatisation reactions used in the chromatographic analysis of chemical warfare agents, their degradation products and metabolites.

The interaction of sarin and soman with plasma proteins: the identification of a novel phosphonylation site

Abstract Incubation of both sarin and soman with human plasma has shown that binding occurs to a tyrosine residue. Similar binding occurs when sarin and soman are incubated with human serum albumin. This binding may provide an important biological marker, which retains full structural information concerning the identity of the agent, in cases of allegations of chemical warfare use.

Detection of trace levels of thiodiglycol in blood, plasma and urine using gas chromatography-electron-capture negative-ion chemical ionisation mass spectrometry

A sensitive method has been developed for the detection and quantitative determination of thiodiglycol in blood, plasma and urine. Samples were extracted from Clin Elut columns and cleaned up on C18 Sep-Pak cartridges (blood, plasma) or Florisil Sep-Pak cartridges (urine). Tetradeuterothiodiglycol was added to the sample prior to extraction as internal standard. Thiodiglycol was converted to its bis-(pentafluorobenzoate) derivative and analysed by capillary gas chromatography-electron-capture negative-ion chemical ionisation mass spectrometry using selected ion monitoring. Levels of thiodiglycol down to 1 ng/ml (1 ppb) could be detected in 1-ml spiked blood and urine samples; calibration curves were linear over the range 5- or 10-100 ng/ml. Blood and urine samples from a number of control subjects were analysed for background levels of thiodiglycol. Concentrations up to 16 ng/ml were found in blood, but urine levels were below 1 ng/ml.

Improved methodology for the detection and quantitation of urinary metabolites of sulphur mustard using gas chromatography-tandem mass spectrometry

Gas chromatography-tandem mass spectrometry (GC-MS-MS) with selected-reaction monitoring was applied to the analysis of urinary metabolites of sulphur mustard, derived from the beta-lyase pathway and from hydrolysis. In the case of beta-lyase metabolites, a limit of detection of 0.1 ng/ml was obtained, compared to 2-5 ng/ml using single stage GC-MS with selected-ion monitoring. GC-MS-MS methodology was less useful when applied to the analysis of thiodiglycol bis(pentafluorobenzoate) using negative-ion chemical ionisation although selected-reaction chromatograms were cleaner than selected-ion chromatograms. The advantage of using GC-MS-MS was demonstrated by the detection of low levels of beta-lyase metabolites in the urine of casualties who had been exposed to sulphur mustard.

Analysis of clothing and urine from moscow theatre siege casualties reveals carfentanil and remifentanil use

On October 26, 2002, Russian Special Forces deployed a chemical aerosol against Chechen terrorists to rescue hostages in the Dubrovka theatre. Its use confirmed Russian military interest in chemicals with effects on personnel and caused 125 deaths through a combination of the aerosol and inadequate medical care. This study provides evidence from liquid chromatography-tandem mass spectrometry analysis of extracts of clothing from two British survivors, and urine from a third survivor, that the aerosol comprised a mixture of two anaesthetics--carfentanil and remifentanil--whose relative proportions this study was unable to identify. Carfentanil and remifentanil were found on a shirt sample and a metabolite called norcarfentanil was found in a urine sample. This metabolite probably originated from carfentanil.

Application of headspace analysis, solvent extraction, thermal desorption and gas chromatography-mass spectrometry to the analysis of chemical warfare samples containing sulphur mustard and related compounds

Abstract Samples of soil, munition fragments and wool, associated with a chemical warfare incident involving sulphur mustard, were analysed using headspace, solvent extraction and thermal desorption techniques combined with full scanning gas chromatography—mass spectrometry. Quantitative analysis was undertaken for sulphur mustard, mustard sulphoxide and thiodiglycol, using solvent extraction and gas chromatography—mass spectrometry with selected ion monitoring. In a soil sample contaminated at ppm (w/w) levels all methods gave positive results for mustard and related compounds. Selected ion monitoring and thermal desorption were the more useful techniques at low ppb (w/w) levels. Cyclic decomposition products 1,4-thioxane and 1,4-dithiane appear to be useful indicators of mustard contamination when using thermal desorption analysis. The hydrolysis product thiodiglycol and hydrolysis/elimination product 2-(vinylthio)ethanol appear to be useful indicators of mustard contamination in soil samples when employing extraction methods.

Methods for the analysis of thiodiglycol sulphoxide, a metabolite of sulphur mustard, in urine using gas chromatography —mass spectrometry

Two methods have been developed for the analysis of thiodiglycol sulphoxide, a metabolite of sulphur mustard, in urine. The first method recovers thiodiglycol sulphoxide from urine by extraction from a solid absorbent tube and clean up on Florisil. In the second method thiodiglycol sulphoxide is reduced to thiodiglycol with acidic titanium trichloride prior to extraction. This method detects thiodiglycol, thiodiglycol sulphoxide, and their acid-labile esters, as the single analyte thiodiglycol. In both cases the recovered analytes were converted to the bis(pentafluorobenzoyl) derivative of thiodiglycol and detected by gas chromatography-mass spectrometry using negative ion chemical ionisation. The limits of detection were 1 ng per 0.5-ml sample of urine. Urine from five normal human subjects showed low background levels of thiodiglycol sulphoxide in the range 2-8 ng/ml. However, a sixth subject was found to be excreting levels of thiodiglycol sulphoxide as high as 36 ng/ml. The first method has been used in toxicokinetic studies of sulphur mustard and the second method is intended to be used for the retrospective confirmation of mustard poisoning in casualties of chemical warfare.

History and perspectives of bioanalytical methods for chemical warfare agent detection

This paper provides a short historical overview of the development of bioanalytical methods for chemical warfare (CW) agents and their biological markers of exposure, with a more detailed overview of methods for organophosphorus nerve agents. Bioanalytical methods for unchanged CW agents are used primarily for toxicokinetic/toxicodynamic studies. An important aspect of nerve agent toxicokinetics is the different biological activity and detoxification pathways for enantiomers. CW agents have a relatively short lifetime in the human body, and are hydrolysed, metabolised, or adducted to nucleophilic sites on macromolecules such as proteins and DNA. These provide biological markers of exposure. In the past two decades, metabolites, protein adducts of nerve agents, vesicants and phosgene, and DNA adducts of sulfur and nitrogen mustards, have been identified and characterized. Sensitive analytical methods have been developed for their detection, based mainly on mass spectrometry combined with gas or liquid chromatography. Biological markers for sarin, VX and sulfur mustard have been validated in cases of accidental and deliberate human exposures. The concern for terrorist use of CW agents has stimulated the development of higher throughput analytical methods in support of homeland security.

Detection of trace levels of trichothecene mycotoxins in environmental residues and foodstuffs using gas chromatography with mass spectrometric or electron-capture detection

Methods are described for the simultaneous detection of a wide range of trichothecenes, including the most polar ones and some macrocyclics, using either gas chromatography-mass spectrometry with selected ion monitoring, or gas chromatography with electron-capture detection. Trichothecenes were extracted directly from the various matrices, or from Clin Elut columns, and cleaned up on Florisil Sep-Pak cartridges. Macrocyclics and neosolaniol were detected after hydrolysis to verrucarol and T-2 tetraol respectively. For optimum sensitivity (0.5-10 ng per sample) over the range, trichothecenes were detected, both before and after hydrolysis of ester groups, as their heptafluorobutyrate derivatives using a quadrupole mass spectrometer and negative ion chemical ionisation. The use of a magnetic sector instrument with electron-impact ionisation gave comparable sensitivity for most trichothecenes, but was less useful for the simultaneous detection of verrucarol in the presence of other trichothecenes. The methods were used to detect the presence of scirpentriol, nivalenol and 15-monoacetoxyscirpendiol in sorghum from Thailand. Trichothecenes in less complex matrices could be detected, after hydrolysis, using gas chromatography with electron-capture detection.