Impurity Profiling of a Chemical Weapon Precursor for Possible Forensic Signatures by Comprehensive Two-Dimensional Gas Chromatography/Mass Spectrometry and Chemometrics

摘要

In this report we present the feasibility of using analyticalnand chemometric methodologies to reveal and exploit thenchemical impurity profiles from commercial dimethylnmethylphosphonate (DMMP) samples to illustrate thentype of forensic information that may be obtained fromnchemical-attack evidence. Using DMMP as a modelncompound of a toxicant that may be used in a chemicalnattack, we used comprehensive two-dimensional gasnchromatography/time-of-flight mass spectrometry (GC ×nGC/TOF-MS) to detect and identify trace organic impuri-nties in six samples of commercially acquired DMMP. ThenGC × GC/TOF-MS data was analyzed to produce impuritynprofiles for all six DMMP samples using 29 analytenimpurities. The use of PARAFAC for the mathematicalnresolution of overlapped GC × GC peaks ensured cleannspectra for the identification of many of the detectednanalytes by spectral library matching. The use of statisticalnpairwise comparison revealed that there were trace im-npurities that were quantitatively similar and differentnamong five of the six DMMP samples. Two of the DMMPnsamples were revealed to have identical impurity profilesnby this approach. The use of nonnegative matrix factoriza-ntion indicated that there were five distinct DMMP samplentypes as illustrated by the clustering of the multiplenDMMP analyses into five distinct clusters in the scoresnplots. The two indistinguishable DMMP samples werenconfirmed by their chemical supplier to be from the samenbulk source. Sample information from the other chemicalnsuppliers supported the idea that the other four DMMPnsamples were likely from different bulk sources. Thesenresults demonstrate that the matching of synthesizednproducts from the same source is possible using impuritynprofiling. In addition, the identified impurities commonnto all six DMMP samples provide strong evidence thatnbasic route information can be obtained from impuritynprofiles. Finally, impurities that may be unique to the sole