Abstract

Nerve agents are acetylcholinesterase inhibitors and among the most toxic chemical warfare agents ever synthesized. Detection of these chemicals is critical for the protection of populations and strategic resources. G-series nerve agents are volatile compounds. V-series nerve agents are persistent phosphonothioate compounds. Persistent nerve agents do not readily volatilize and can contaminate environmental resources for extended periods. While nerve agents are inherently non-electroactive, they can be hydrolyzed to electroactive products compatible with electrochemical sensing. Zr(IV) MOFs are next-generation nanoporous materials, which have been shown to rapidly catalyze nerve agent hydrolysis. In this work, the catalytic processes of MOF-808, a specific Zr(IV) MOF, towards nerve agents are leveraged to develop novel Zr(IV) MOF-enabled electrochemical sensors capable of sensitively detecting both G-series and V-series nerve agents. Initially, a Zr(IV) MOF-enabled potentiometric sensor was developed for G-series nerve agent detection. The potentiometric sensor was tested using G-series nerve agent simulants, dimethyl methylphosphonate (DMMP) and diisopropyl fluorophosphate (DIFP). The potentiometric sensor had a limit-of-detection (LOD) of 185 and 20 ÂµM for DMMP and DIFP, respectively. Following the potentiometric sensor, a Zr(IV) MOF-enabled voltammetric sensing strategy using sequential hydrolysis and detection for low-concentration detection of V-series nerve agents was developed. The full range of operation for the V-series nerve agent sensor was demonstrated using MOF-808 and a V-series nerve agent simulant, demeton-S methylsulphon (DMTS). MOF-808 was shown to rapidly, selectively, and completely hydrolyze DMTS into electroactive products. A LOD of 30 nM for DMTS was measured for this preliminary sensor. A sensor platform was developed to improve sensor applicability with smaller sample sizes and concurrent hydrolysis and detection. Furthermore, various alkaline buffers were studied to minimize background currents. The response of the developed sensor was evaluated for both DMTS and VX and demonstrated an LOD of 4 ÂµM and 10 ÂµM, respectively. The sensor also detected the presence of DMTS and VX from environmental samples in a simulated warfare scenario. This work demonstrates the feasibility of sensitive, rapid, and robust electrochemical sensing of both G-series and V-series nerve agents for in-field applications.

Degree

PhD

College and Department

Ira A. Fulton College of Engineering; Chemical Engineering

Rights

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