PREPARATION, DERIVATIZATION WITH TRIMETHYLSILYLDIAZOMETHANE, AND GC/MS ANALYSIS OF A “POOL” OF ALKYL METHYLPHOSPHONIC ACIDS FOR USE AS QUALITATIVE STANDARDS IN SUPPORT OF COUNTERTERRORISM AND THE CHEMICAL WEAPONS CONVENTION

Abstract

There are hundreds of nerve agents in the class of alkyl methylphosphonofluoridates covered by Schedule 1 of the CWC (Chemical Weapons Convention). Hydrolysis of these sarin-like nerve agents results in an equal number of alkyl methylphosphonic acids. These alkyl methylphosphonic acids are persistent and provide good evidence of specific agent production or use. In order to support the CWC and counterterrorism activities, it is desirable to have ready access to each of these hydrolysis products for use as qualitative standards. A means for simultaneously producing multiple alkyl methylphosphonates from methylphosphonic acid and the corresponding alcohols was developed. Derivatization of these alkyl methylphosphonic acids with trimethylsilyldiazomethane yields the corresponding methyl esters which are suitable for GC/MS analysis.

Keywords:

• Alkyl methylphosphonic acid
• chemical warfare agents
• counterterrorism
• esterification
• mass spectra
• trimethylsilyldiazo-methane

Notes

*Convention on the Prohibition of the Development, Stockpiling, and Use of Chemical Weapons and on their Destruction, United States Arms Control and Disarmament Agency, Washington, D.C., 1993. As of December 31, 2001 there were 145 State Parties to the CWC, www.opc.org.

** The OPCW is responsible for monitoring the CWC.

*** Prof. Hoffmann, while suggesting alternatives for the term “library,” noted that “pool” was initially used by combinatorial chemists. ³