GB degradation products

Sarin (GB) 1 cylinder, 10 bomblets Water, MEA, GB degradation products, volatile and semivolatile organics, metals... 

Table 2.4 Acute exposure data for GB degradation products and impurities. Table taken from Reference [5] with permission from Environmental Health Perspectives...

Diisopropyl methylphosphonate is an organophosphate compound that was first produced in the United States as a by-product of the manufacture of the nerve gas isopropyl methylphosphonofluoridate (GB, or Sarin) (ATSDR 1996 EPA 1989 Robson 1977, 1981). It is not a nerve gas and is not a metabolite or degradation product (Roberts et al. 1995). Diisopropyl methylphosphonate constitutes approximately 2-3% of the crude GB product, but it is neither a metabolite nor a degradation product of GB (EPA 1989 Rosenblatt et al. 1975b). Diisopropyl methylphosphonate is not normally produced except for its use in research. One method of producing diisopropyl methylphosphonate is to combine triisopropyl phosphite and methyl iodide. The mixture is then boiled, refluxed, and distilled, yielding diisopropyl methylphosphonate and isopropyl iodide (Ford-Moore and Perry 1951). Diisopropyl methylphosphonate may also be prepared from sodium isopropyl methylphosphonate by a reaction at 270° C, but a portion of the resulting diisopropyl methylphosphonate is converted to trimethylphosphine oxide at this temperature (EPA 1989). 

It can be seen that the spectra are very similar. This was also observed within the experimental spectra. For HD and VX theoretical spectra were also used for the cluster analysis. The Clnster Analysis was done by making the assnmption that the theoretical spectra of GB, HD and VX are more closely related to the real spectra of GB, HD and VX than the experimental spectra of the simnlants and degradation products. This assumption is based on the comparisons that were done before and on the fact that this is the procednre nsed by most researchers where the theoretical and experimental spectra are compared nsing DFT °. 

Breakdown of GB results in only a few degradation products (see the Appendix, Table A5) and these are predicted to be relatively nontoxic (Rosenblatt et al, 1995). The hydrolysis products are acids, and their presence increases the rate of hydrolysis. The rate of hydrolysis under natural conditions is accelerated by the presence of certain hydroxy cations in solution, such as Cu(OH)+, Ca(OH)+ andMn(OH)+ (Epstein and Rosenblatt, 1958). Metal cations, such as copper and manganese, in seawater also increase the rate of hydrolysis (Epstein, 1974). 

Table A5. Degradation products, impurities and stabilizers of agent GB ...

LC-MS is a powerful method used to detect and quantify CWAs. The use of LC-MS for CWA and hydrolysis product detection has been reviewed [7,20,26]. LC-MS methods are often used to detect CWA hydrolysis/ degradation products instead of the active agents [27-28]. LC-MS serves as a bioanalytical method for CWA detection in living systems and its contributions have also been reviewed [7, 26, 29]. A LC-MS method using an on-line trypsin digestion is used to identify GB and sulfur mustard adducts with proteins and enzymes like human butyryl cholinesterase [30]. This technique, along with similar techniques, could be applied to confirm CWA exposure when illness is suspected from an unknown toxin. 

Of topical interest is the investigation of Vermillion and Crenshaw [146] on the analysis of nerve gas degradation products in soil samples. They investigated isopropylmethylphosphonic acid (IMPA) and methylphosphonic acid (MPA) that are formed via hydrolysis of GB (sarin) under environmental conditions (Figure 10.64). In the vicinity of former production sites and future incineration plants, these two components pose a potential environmental risk, so a simple... 

Figure 10.65 Separation of the GB (sarin) degradation products IMPA und MPA in soii sam-pies. Separator coiumn 2 Sarasep AN 300 (100mm X 7.5mm i.d.) eiuent lOmmoi/L Na2B407 + 3.75 mmoi/L NaOH flow rate 1.5mL/min detection suppressed conductivity injection volume 250 pU peaks (a)...

Fig. 9-33. Separation of the GB (sarin) degradation products iMPA und MPA in soil samples. - Separator column ...

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