A practical and efficient protocol for the derivatization and detection by EI-GC-MS of isopropyl-, pinacolyl- and cyclohexyl methylphosphonic acids, key diagnostic degradation products of the nerve agents sarin, soman and cyclosarin respectively, in six different types of soils will be presented. The method involves the in situconversion of the phosphonic acids to their respective methyl esters using trimethyloxonium tetrafluoroborate when present at low levels (10 μg g-1). The soils employed in our study were Nebraska EPA soil, Georgia soil, silt, Virginia type A soil, regular sand and Ottawa sand and were chosen for their vast differences in composition and physical attributes. Appealing attributes of the protocol include its rapidity (t &lt; 30 min.), mildness (ambient temperature), and practicality that includes the production of the phosphonic methyl esters that can be easily detected by EI-GC-MS and corroborated with the instrument’s internal NIST spectral library or the Organisation for the Prohibition of Chemical Weapons (OPCW) central analytical database (OCAD v.21_2019). The overall efficacy of the protocol was then tested on a soil sample featured in the 44thOPCW PT that our laboratory participated in. After preparing the soil so as to give pinacolyl methylphosphonic acid at a 5 μg g-1concentration, the acid was successfully methylated and detected by EI-GC-MS.

Practical derivatization protocol for phosphonic acid markers of G-agents at low levels in various soils

2019 Fall National Meeting

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