Mass Spectrometric Identification of Chemical Defence Compounds in Soil Extracts

Paul A. D'Agostino, James R. Hancock and Claude L. Chenier
Defence Research Establishment Suffield
P.O. Box 4000 Stn. Main, Medicine Hat, Alberta, CANADA, T1A 8K6

Abstract

More than 140 State Parties have ratified the Chemical Weapons Convention (CWC) and agreed not to develop, produce, stockpile, transfer or use chemical weapons and agreed to destroy their own chemical weapons and production facilities. The CWC has reduced the likelihood of chemical weapons use by State Parties, but there remains a serious concern that other parties may make use of these weapons against civilian or military targets. Analytical methods need to be developed to ensure that suspect samples collected under these scenarios can be analysed for the presence of chemical warfare agents in a timely manner.

Gas chromatography has been used extensively for the separation and identification of the chemical warfare agents, with GC-MS being used most frequently for the characterization of compounds scheduled under the CWC. GC separation, while suitable for the analysis of organophosphorus chemical warfare agents in organic extracts, is usually not preferred for the direct analysis of aqueous samples. Aqueous samples containing chemical warfare agents and/or their nonvolatile hydrolysis products normally require additional sample handling steps and derivatization prior to GC-MS analysis. Increasingly, researchers have turned to LC-MS methods to allow direct analysis of aqueous samples and extracts.

A sample handling and packed capillary LC-ESI-MS analysis method was developed for the identification of chemical warfare agents, their hydrolysis products and related compounds in aqueous extracts of contaminated soil samples. The method was compared to the existing GC-MS method using soil samples spiked at the 10 mg/g with sarin, soman and their hydrolysis products and was recently applied to the analysis of soil samples collected from a former mustard storage site as part of an environmental assessment. Hydrolysis products of mustard and longer chain sulfur vesicants, including thiodiglycol, were detected and characterized during LC-ESI-MS analysis of these samples.