title: Impurity profiling to match a nerve agent to its precursor source for chemical forensics applications.
abstract: Chemical forensics is a developing field that aims to attribute a chemical (or mixture) of interest to its source by the analysis of the chemical itself or associated material constituents. Herein, for the first time, trace impurities detected by gas chromatography/mass spectrometry and originating from a chemical precursor were used to match a synthesized nerve agent to its precursor source. Specifically, six batches of sarin (GB, isopropyl methylphosphonofluoridate) and its intermediate methylphosphonic difluoride (DF) were synthesized from two commercial stocks of 97% pure methylphosphonic dichloride (DC); the GB and DF were then matched by impurity profiling to their DC stocks from a collection of five possible stocks. Source matching was objectively demonstrated through the grouping by hierarchal cluster analysis of the GB and DF synthetic batches with their respective DC precursor stocks based solely upon the impurities previously detected in five DC stocks. This was possible because each tested DC stock had a unique impurity profile that had 57% to 88% of its impurities persisting through product synthesis, decontamination, and sample preparation. This work forms a basis for the use of impurity profiling to help find and prosecute perpetrators of chemical attacks.
authors: Pacific Northwest National Laboratory, Richland, Washington 99352, United States. carlos.fraga@pnnl.gov
authors: Carlos G
authors: CG
authors: Fraga
authors: Gabriel A Pérez
authors: GA
authors: Acosta
authors: Michael D
authors: MD
authors: Crenshaw
authors: Krys
authors: K
authors: Wallace
authors: Gary M
authors: GM
authors: Mong
authors: Heather A
authors: HA
authors: Colburn
mesh_terms: D002619:Chemical Warfare Agents / Q000032:analysis* / Q000138:chemical synthesis; D016000:Cluster Analysis; D005554:Forensic Medicine; D008401:Gas Chromatography-Mass Spectrometry; D009943:Organophosphorus Compounds / Q000032:analysis / Q000138:chemical synthesis; D012524:Sarin / Q000032:analysis / Q000138:chemical synthesis
chemical_list: D002619:Chemical Warfare Agents; D009943:Organophosphorus Compounds; C046675:methylphosphonic difluoride; D012524:Sarin