Sarin mass spectra

Alkylphosphonochloridates may be used as starting materials for the synthesis of the corresponding alkylphosphonofluoridates. Two of these compounds, chlorosarin and chlorosoman (see Table 1), are placed on the CWC Schedule 1 list. The main peaks in the El mass spectrum of chlorosarin (MW 156) at mlz 115/117 (loss of C3H5) and mlz 141 (loss of CH3) are in accordance with the fragmentation pattern of sarin. The same analogy applies to chlorosoman (MW 198) with abundant ions at m/z 142/144 (loss of C4H8) and m/z 115/117 (loss of CsHn), and soman (10). 

Another interesting development is comprehensive GC-MS. Comprehensive GC offers great selectivity and resolution and is ideal for complex samples such as biomedical samples. Its combination with time-of-flight mass spectrometry offers the possibility to analyze in full-scan mode, not target-directed, with the availability of a full mass spectrum that will meet the forensic standards. The utility has been demonstrated for the detection of CWAs in complicated matrices such as fuel (Reichenbach et al., 2003). The method has also been used for the analysis of regenerated sarin in inhibited plasma (van der Meer et al., 2010). Finally, it may be expected that the sample preparation will be more or less automated. Recently, a promising result was published by Carol-Visser et al. (2008), who described the digestion and analysis of sulfur mustard adducts in albumin and the sarin adduct to BuChE. 

Fidder et al. introduced an electrospray-ionization tandem mass spectrometry method for diagnosing OP exposure by measuring the mass of the OP-labeled active site peptide of human butyrylcholinesterase (Fidder et al, 2002). His starting material was 0.5 ml of human plasma from a victim of the Tokyo subway attack. The mass of the active site peptide was higher by 120 atomic mass units, compared to the mass of the unlabeled active site peptide. This added mass was exactly the added mass expected from sarin. The peptide s MS-MS fragmentation spectrum yielded the sequence of the peptide, and verified that the OP label was on serine 198, the active site serine. Examples of the MS-MS spectra from tryptic peptides of pure, OP-labeled human butyrylcholinesterase are shown in Figure 56.1. 

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