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Title: Stable-carbon isotope ratios for sourcing the nerve-agent precursor methylphosphonic dichloride and its products

Abstract

The ability to connect a chemical threat agent to a specific batch of a synthetic precursor can provide a fingerprint to contribute to effective forensic investigations. Stable isotope analysis can leverage intrinsic, natural isotopic variability within the molecules of a threat agent to unlock embedded chemical fingerprints in the material. Methylphosphonic dichloride (DC) is a chemical precursor to the nerve agent sarin. It is converted to methylphosphonic difluoride (DF) as part of the sarin synthesis process. We used a suite of commercially available DC stocks to both evaluate the potential for δ13C analysis to be used as a fingerprinting tool in sarin-related investigations and to develop sample preparation techniques (using chemical hydrolysis) that can simplify isotopic analysis of DC and its synthetic products. We demonstrate that natural isotopic variability in DC results in at least three distinct, isotope-resolved clusters within the thirteen stocks we analyzed. Isotopic variability in the carbon feedstock (i.e., methanol) used for DC synthesis is likely inherited by the DC samples we measured. We demonstrate that the hydrolysis of DC and DF to methylphosphonic acid (MPA) can be used as a preparative step for isotopic analysis because the reaction does not impart a measureable isotopic fractionation. MPAmore » is more chemically stable, less toxic, and easier to handle than DC or DF. Further, the hydrolysis method we demonstrated can be applied to a suite of other precursors or to sarin itself, thereby providing a potentially valuable forensic tool.« less

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1452866
Report Number(s):
PNNL-SA-130651
Journal ID: ISSN 0039-9140; 45304036B
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Talanta; Journal Volume: 186; Journal Issue: C
Country of Publication:
United States
Language:
English

Citation Formats

Moran, James J., Fraga, Carlos G., and Nims, Megan K. Stable-carbon isotope ratios for sourcing the nerve-agent precursor methylphosphonic dichloride and its products. United States: N. p., 2018. Web. doi:10.1016/j.talanta.2018.04.021.
Moran, James J., Fraga, Carlos G., & Nims, Megan K. Stable-carbon isotope ratios for sourcing the nerve-agent precursor methylphosphonic dichloride and its products. United States. doi:10.1016/j.talanta.2018.04.021.
Moran, James J., Fraga, Carlos G., and Nims, Megan K. Wed . "Stable-carbon isotope ratios for sourcing the nerve-agent precursor methylphosphonic dichloride and its products". United States. doi:10.1016/j.talanta.2018.04.021.
@article{osti_1452866,
title = {Stable-carbon isotope ratios for sourcing the nerve-agent precursor methylphosphonic dichloride and its products},
author = {Moran, James J. and Fraga, Carlos G. and Nims, Megan K.},
abstractNote = {The ability to connect a chemical threat agent to a specific batch of a synthetic precursor can provide a fingerprint to contribute to effective forensic investigations. Stable isotope analysis can leverage intrinsic, natural isotopic variability within the molecules of a threat agent to unlock embedded chemical fingerprints in the material. Methylphosphonic dichloride (DC) is a chemical precursor to the nerve agent sarin. It is converted to methylphosphonic difluoride (DF) as part of the sarin synthesis process. We used a suite of commercially available DC stocks to both evaluate the potential for δ13C analysis to be used as a fingerprinting tool in sarin-related investigations and to develop sample preparation techniques (using chemical hydrolysis) that can simplify isotopic analysis of DC and its synthetic products. We demonstrate that natural isotopic variability in DC results in at least three distinct, isotope-resolved clusters within the thirteen stocks we analyzed. Isotopic variability in the carbon feedstock (i.e., methanol) used for DC synthesis is likely inherited by the DC samples we measured. We demonstrate that the hydrolysis of DC and DF to methylphosphonic acid (MPA) can be used as a preparative step for isotopic analysis because the reaction does not impart a measureable isotopic fractionation. MPA is more chemically stable, less toxic, and easier to handle than DC or DF. Further, the hydrolysis method we demonstrated can be applied to a suite of other precursors or to sarin itself, thereby providing a potentially valuable forensic tool.},
doi = {10.1016/j.talanta.2018.04.021},
journal = {Talanta},
number = C,
volume = 186,
place = {United States},
year = {Wed Aug 01 00:00:00 EDT 2018},
month = {Wed Aug 01 00:00:00 EDT 2018}
}