Sarin detection limits

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). 

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). 

The active site of organophosphorus hydrolase (OPH) contains two metal atoms (zinc in the wild-type enzyme) and catalyzes hydrolysis of numerous organophos-phate compounds including pesticides as well as chemical warfare agents such as sarin and soman. Rates of OPH catalyzed hydrolysis of organophosphates exceed those of chemical hydrolysis by NaOH at 4°C by factors of 40 to 2450 [41-43]. The enzyme has been described for use in sensor systems with exceptional detection limits reported for response times on the order of 10 seconds [44-48]. However, the presence of OP/CWA is detected by the inhibition of enzymatic rate determined by comparing rate measnrements in the presence and absence of the analyte. 

As reversible, competitive inhibitors of enzymes, porphyrins can be used for identification and quantification of a substrate or other competitive inhibitors of enzymes. This approach has been successful in the development of cholinesterase and organophosphorus hydrolase bearing glass surfaces for the detection of substrates and inhibitors, including organophosphate compounds. The technique has demonstrated detection limits for sarin (GB) below the Immediately Dangerous to Life or Health levels mdicated by CDC/NIOSH. 

The detection limit at 220 nm was 0.2 mmol, i.e.0.028 Mg/ml for Sarin at the saisitivity of the UV detector 2 a.u.f s. This sensitivity respcmds to the concentration of Sarin 28 pg/1 of original sample and it was possible to improve it about two order by utilization of higher sensitivity of the detectitm. 4-nitro-phenol is stabile compound. The dhromatograms are showed on Figure 3 and 4. 

Reverse phase column with water/methanol as mobile phase Detection limits 10 pg for sarin (GB), 60 pg tabun (GA)... 

Usually detection limits for sulfur mustard are in the region of 0.1 mg m [41-46]. An interesting application of a miniaturized aspiration condenser-type ion mobility spectrometer for fast detection of chemical warfare agents has been reported. The device was tested at the Armed Forces Scientific Institute for Protection Technologies-NBC-Protection, Germany, to evaluate the analytical performance. The spectra of different chemical warfare agents, such as Sarin, Tabun, Soman, US-VX, Sulfur Mustard, Nitrogen Mustard and Lewisite were recorded at various... 

Apart from the Chirasil-L-Val method, sarin enantiomers were also separated by a 2D-GC technique on chiral Cyclo-dex B material prior to NPD monitoring (Spruit et al., 2000, 2001). An additional GC-based approach allowed baseline separation of cyclosarin enantiomers on a GAMMA DEX column monitored by EI-MS (Reiter et al, 2007). VX enantiomers were chromatographed on a Chiracel OD column by LC coupled to an electrochemical detector yielding a lower limit of quantification of about lOng/ml blood (Van der Schans et al, 2003). To our knowledge no chiral HPLC-MS separation of OPCs has been described so far although mobile phases are compatible with MS detection. 

The common nerve agents that are encountered in chemical warfare agent-filled munitions are isopropyl methylphosphonofluoridate (GB or sarin), pinacolyl methylphosphonofluoridate (GD or soman), and O-ethyl, S-(N,N-diisopropyl)aminoethyl methylphosphonothio-late (VX). These compounds are acutely toxic, with median lethal dose (LD50) values on the order of tens of micrograms per kilogram for humans, which make detection of trace quantities extremely important, and also render them difficult to handle in conducting analytical experiments. Given this limitation, the small size and ease of operation are favorable attributes of the... 

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