Soman detection

Acoustic wave sensors are also used to detect nerve and blister agents. The surface acoustic wave chemical agent detector (SAW Mini-CAD) is a commercially available, pocket-sized instrument that can monitor for trace levels of toxic vapors of sulfur-based mustard agents (e.g., distilled mustard) and G nerve agents (e.g., tabun, sarin, soman) with a high degree of specificity. Colorimetric tubes are the... 

Jenkins AL, Uy OM, Murray GM. Polymer-based lanthanide luminescent sensor for detection of the hydrolysis product of the nerve agent Soman in water. Anal Chem 1999 71 373-378. 

Jenkins et al. produced a fiber optic based luminescence sensor designed to measure a hydrolysis product of the nerve agent soman (GD) in water. The sensor exhibited high selectivity, no interference from organophophorous (OP) herbicides or pesticides, and high sensitivity, with a limit of detection of 600 fg/mL in water (10). 

Branching of the O-alkyl ester chain of organo-phosphorus compounds may introduce an asymmetric center, which together with an asymmetric substituted phosphorus atom creates a number of stereoisomers. Diastereoisomers may even be separated on a conventional capillary GC column. This is, for instance, the case with the nerve gas soman, which usually produces two peaks in a gas chromatogram. Although this is characteristic for identifying soman, it also increases the GC/MS detection limit by a factor of two. 

The development of procedures for the identification of CW agents in biomedical samples is ongoing and existing procedures are continuously improved. Quantization is also an important factor, and an isotope dilution GC/MS/MS method was developed for the quantitative determination of five organophosphorus acids derived from the nerve agents VX, tabun, sarin, soman, and cyclohexyl sarin in urine samples. The acids were isolated and converted into their methyl esters by diazomethane. Detection limits in the low p,g I. 1 were obtained using CID of the protonated molecular ion peaks obtained with isobutane Cl(58). 

P.A. D Agostino and L.R. Provost, Detection of sarin and soman in a complex airborne matrix by capillary column ammonia chemical ionization gas chromatography-mass spectrometry and gas... 

Sarin and soman have been shown to bind to a tyrosine residue present in a blood protein (51). The precise site of this residue has not yet been confirmed but it is associated with the albumin fraction. An LC/ESI/MS/MS (triple quadrupole) method was developed for its detection after digestion of the albumin fraction with Pronase and clean up on a C18 SPE (solid-phase extraction) cartridge. A... 

It is unlikely that the unchanged nerve agent would be detected in the blood or tissues of a casualty unless samples were collected very soon after the exposure. A number of methods have been reported for the analysis of nerve agents in blood, for application to animal studies. These involve simple liquid or SPE extraction, for example, using chloroform (sarin, soman) (47), C18 SPE (sarin, soman) l48 49 , ethyl acetate (VX) (50), usually after precipitation of proteins, and analysis by GC/MS or gas chromatography/nitrogen-phosphorus detection (GC/NPD). Sarin bound to cholinesterase and displaced with fluoride ion was extracted by C18 SPE (see Part B) (51). 

H.C. De Bisschop and E. Michiels, Assay of the nerve agent soman in serum by capillary gas chromatography with nitrogen-phosphorus detection and splitless injection, Chromatographia, 18, 433-436 (1984). 

After Pronase digestion of plasma, the analytes were concentrated on a C18 or C8 cartridge and analyzed by LC/MS/MS. The adducts have been detected in the blood of guinea pigs 24 h after being exposed to 0.5 LD50 doses of sarin and soman. It is not known if they are formed in cases of human exposure. 

Sarin and its corresponding nontoxic hydrolysis products (IMPA, and additional methyl phosphonic acids) are predominantly eliminated via the kidneys which are thus more important for detoxification than the liver (Little et al, 1986 Waser and Streichenberg, 1988). Urinary excretion happens quite rapidly as demonstrated for single dose s.c. application of sarin, cyclosarin, and soman to rats (Shih et al, 1994). The terminal elimination half-life was found to be 3.7 =E 0.1 h for sarin and 9.9 0.8 h for cyclosarin. In contrast soman showed a biphasic elimination with terminal half-fives of about 18.5 h and 3.6 h (Shih et al, 1994). Maximum peak levels of sarin metabolites in urine were detected 10-18 h after exposure (Minami et al, 1997) and after 2 days hydrolyzed sarin metabolites had been excreted nearly quantitatively (Shih et al, 1994). In contrast, even at 5 days post-exposure soman metabolite recovery was only 62% (Shih et al, 1994). Excretion of soman from blood, fiver, and kidney compartments following cfiemical and enzymatic hydrolysis is considered a first-order elimination process (Sweeney et al, 2006). 

Adams, T.K., Capacio, B.R., Smith, J.R., Whalley, C.E., Korte, W.D. (2004). The application of the fluoride reactivation process to the detection of sarin and soman nerve agent exposure in biological samples. Drug Chem. Toxicol. 27 77-91. 

The recent study of Williams et al (2007) found that sarin, soman, cyclosarin, and tabun phosphylate a tyrosine residue on albumin in human blood. The tyrosine adducts with soman and tabun were detected in guinea pigs receiving therapy 7 days following subcutaneous administration of five times the LD50 dose of the respective nerve agent. VX also forms a tyrosine adduct in human blood in vitro but only at high concentrations. 

Soman Urine PMPA Detected in urine of rhesus monkeys GC-NPD, FPD, MS LC-MS Riches et al (2005)... 

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