Nerve agents characteristics

Solvents have been added to nerve agents to facilitate handling, to stabilize the agents, or to increase the ease of percutaneous penetration by the agents. Percutaneous enhancement solvents include dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylpalmitamide, N,N-dimethyldecanamide, and saponin. Color and other properties of these solutions may vary from the pure agent. Odors will vary depending on the characteristics of the solvent(s) used and concentration of nerve agent in the solution. 

Characteristics Nerve agents are liquid under temperate conditions, but, when dispersed, the more volatile ones constitute both a vapor and a liquid hazard. However, the less volatile nerve agents represent primarily a liquid hazard (mainly, the G-agents are more volatile than the nerve agent VX, while sarin (GB) is the most volatile and nerve agent GF is the least volatile of the so-called G-agents. GB has an LCt-50 of 100 (vapor toxicity of mg-min/m3), an ICt-50 of 75 (vapor toxicity of mg-min/m30, and an MCt-50 of 3 (vapor toxicity of mg-min/m3). The LD-50 on skin is 1700mg. 

P=0 Thomas and Chittenden (5,38 441 have carried out a thorough series of studies on the identification of organophosphorus compounds. The group frequency tables in these studies enable interpretation of many of the characteristic features in the spectra of nerve agents and related chemicals. Several structure-spectrum relationships give specific information on the molecule. One very valuable relation discovered by Thomas is the dependence of the position of the P=0 bond stretching vibration, vp=0, on the substituents on the phosphorus, represented by n constants ... 

A PPy/PQQ modified GC electrode was used for amperometric detection of V-type nerve agent decomposition products. The electropolymerization of pyrrole was efficiently used for immobilization of the biocatalyst, PQQ. The introduction of CaCl2 as a supporting electrolyte during electrodeposition significantly improves the response of the sensor to DMAET and DEAET. Amperometric studies targeted to detection of DMAET and DEAET by PPy/PQQ electrode were performed at a constant potential set at 0.25 V, and the electrode characteristics such as sensitivity and the analyte detection limit were determined. 

Interaction of CarbE with nerve agents follows a kinetic of first order characterized by inhibition of CarbE at the active site serine residue described by a bimolecular rate constant, ki (Maxwell and Brecht, 2001). For noncharged nerve agents (e.g. sarin and soman) the ki of rat serum CarbE was found to be >10 M min whereas cationic substrates (e.g. VX) are converted with poor reactivity (ki < 10" M min ). This specificity is explained by the electrostatic characteristics of the large active site containing only a few cation-II bonding and anionic residues (Maxwell and Brecht, 2001 Satoh and Hosokawa, 2006). 

Both the toxicodynamics and toxicokinetics of OP nerve agents can be explained by their biochemical characteristics of interacting with cholinesterases and other hydrolases. Inhibition of cholinesterases in the blood is the first target for OPs according to the principle of first come, first served (Benschop and de Jong, 2001). 

Although miosis is a characteristic sign of exposure to the nerve agent, rhinorrhea may be the first indication. It severity is dose dependent. 

---