Raymond J. Clarke

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.

Biological fate of sulphur mustard: identification of valine and histidine adducts in haemoglobin from casualties of sulphur mustard poisoning

1. Analytical methods were developed for the detection of N-terminal valine and histidine adducts in haemoglobin alkylated with sulphur mustard. 2. N-(2-hydroxyethylthioethyl)-N-terminal valine was selectively cleaved from globin with the Edman reagent pentafluorophenyl isothiocyanate. The resulting thiohydantoin derivative was analysed by high resolution gc-ms using negative ion chemical ionization. An alternative procedure, involving acid hydrolysis of globin to its constituent amino acids and conversion of the adduct to its di-TBDMS derivative, was less sensitive. 3. N-(2-hydroxyethylthioethyl)histidine was analysed, after acid hydrolysis of globin, as its fluorenylmethyloxycarbonyl derivative by lc-ms-ms using electrospray ionisation and selected reaction monitoring. 4. N-(2-hydroxyethylthioethyl)valine and (2-hydroxyethylthioethyl)histidine were detected in globin isolated from a rat treated percutaneously with sulphur mustard, and in globin from five blood samples collected from human casualties of sulphur mustard poisoning. The adducts are proposed as biological markers of sulphur mustard poisoning. in addition to urinary metabolites and DNA adducts.

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.

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.

THE CHEMISTRY OF 1,1′-THIOBIS(2-CHLOROETHANE) (SULPHUR MUSTARD) PART II.1 THE SYNTHESIS OF SOME CONJUGATES WITH CYSTEINE, N-ACETYLCYSTEINE AND N-ACETYLCYSTEINE METHYL ESTER

Abstract The syntheses of a number of conjugates of 1,1′-thiobis(2-chloroethane) (“sulphur mustard”) and its simple derivatives with cysteine, N-acetylcysteine and N-acetylcysteine methyl ester are described. These compounds were synthesised for use as reference compounds to support metabolite identification in metabolic studies and, in some cases, to provide standards for analytical procedures being developed for the retrospective confirmation of exposure to sulphur mustard.

The metabolism of dibenz[b,f]-1,4-oxazepine (CR): in vivo hydroxylation of 10,11-dihydrodibenz[b,f]-1,4-oxazepin-11-(1OH)-one and the NIH shift.

Studies of the in vivo metabolism of 10,11-dihydrodibenz[b,f]-1,4-oxazepin-11-(1OH)-one (2) specifically deuteriated at C-7 implicate an arene oxide intermediate during the conversion to 7-hydroxy-2 (4) as evidenced by the observation of the NIH shift.

Preparation of the eight monohydroxydibenz[b,f][1,4]oxazepin-11(10H)-ones

The eight possible isomeric monohydroxydibenz[b,f][1,4]oxazepin-11(10H)-ones have been prepared and their mass spectra determined. With the exception of the 7-hydroxy-derivative the fragmentation patterns of the isomers were similar, although the relative line intensities allowed distinctions between the isomers to be made. The syntheses of several irritant monomethoxydibenz[b,f][1,4]oxazepines are also described.