Sarin detection

There are no measurements of the actual concentrations of diisopropyl methylphosphonate in groundwater at the RMA during the years of active production of the nerve gas Sarin (i.e., 1953-1957) (EPA 1989). The first actual measurements of the concentration of diisopropyl methylphosphonate in the groundwater on the arsenal and surrounding property to the north and west were made in 1974 (Robson 1981). The concentrations of diisopropyl methylphosphonate in the groundwater ranged from 0.5 g/L (analytical detection limit) to as much as 44,000 g/L near the abandoned waste disposal ponds. Diisopropyl methylphosphonate was discharged into a lined reservoir at the RMA in 1956 and was still present 20 years later in concentrations of about 400,000 g/L (Robson 1977). 

Exposure. No biomarkers of exposure were identified that were specific to diisopropyl methylphosphonate. Although standard procedures exist for identifying diisopropyl methylphosphonate s primary metabolite (IMP A) in plasma, urine, and feces (Weiss et al. 1994), the detection of IMP A is not unique to diisopropyl methylphosphonate exposure. IMPA is also a major metabolite of GB (Sarin) (Little et al. 1986). In addition, IMPA is cleared from the body rapidly, making it a useful indicator for recent exposure only. 

Polhuijs, M., Langenberg, J.P., and Benschop, H.P. (1997). New method for retrospective detection of exposure to organophosphorus anticholinesterases application to alleged sarin vicitims of Japanese terrorists. Toxicol. Appl. Pharmacol., 146, 156-161. 

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... 

In Japan, a number of years ago, a terrorist attack with sarin killed a dozen individuals confined to a subway car out of roughly a thousand people in the nearby vicinity. Sarin has little effect on the skin, due to rapid evaporation. It is true that the Iraqis killed many Kurds with nerve gas, but the victims were unprepared, had no training, no detection devices, no masks or other protection, no antidote and no practical way to avoid the gas. None of these vulnerabilities would be the case in a conflict with American troops. 

K.J. Ewing, B. Lemer, Infrared detection of the nerve agent sarin (isopropyl methylpho-sphonofluoridate) in water using magnesium oxide for preconcentration. Appl. Spectrosc. 55, 407M11 (2001)... 

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... 

Fidder and coworkers (50) developed a versatile procedure that identifies phosphylated butyrylcholi-nesterase. Adducted butyrylcholinesterase is isolated from plasma by affinity chromatography (procainamide column), digested with pepsin, and a nonapep-tide containing the phosphylated active-site serine residue detected using LC/ESI/MS/MS (quadrupole-TOF hybrid instrument). A C18 150 x 0.3-mm LC column was used, eluted with a gradient of water-acetonitrile-0.2 % formic acid. The method was applied successfully to casualties of sarin poisoning from the Tokyo subway attack (see Chapter 17). 

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). 

Very high levels of MPA and /-PrMPA were detected as their TBDMS derivatives by GC/FPD in the urine of a Matsumoto casualty rendered unconscious and with low-blood AChE activity (42). Urine was collected over a 7-day period. Concentrations of i-PrMPA and MPA respectively were day 1, 760 ng/ml and 140 ng/ml day 3, 80 ng/ml and 20 ng/ml day 7, 10 ng/ml, MPA not detected (no standard of i -PrMPA was available and quantitation was based on detector response to MPA). The exposure was estimated as 2.79 mg of sarin, making crude assumptions on the percentage that would be excreted, i -PrMPA was detected as the... 

TMS derivative by GC/FPD in urine collected over 7 days from casualties of the Tokyo attack (43). Concentrations were not reported but the estimated exposures were 0.13-0.25 mg of sarin in a comatose patient and 0.016-0.032 mg in less severely intoxicated patients. Using LC/MS/MS and a more rigorous method of quantitation, /-PrMPA was detected underivatized in serum at concentrations of 3-136ng/ml in four casualties of the Matsumoto incident and 2-100ng/ml in 13 casualties of the Tokyo attack (59). All samples were taken within 2.5 hours of hospitalization. High levels of /-PrMPA correlated with low levels of butyryl-cholinesterase activity. Other positive analyses associated with these incidents were obtained by identification of inhibited cholinesterase, and are reported in Part B. 

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