Novel colorimetric mustard sensing in surfactant and microemulsion systems

Thomas, Bria 2022. Novel colorimetric mustard sensing in surfactant and microemulsion systems. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Chemical warfare agents (CWAs) have an unfortunately long history with various military and terrorist groups choosing to employ these highly toxic chemicals. The unrestricted stockpiling and development of CWAs led to the introduction of the Chemical Weapons Convention (CWC) in 1993 which outlawed these practices. Despite this, their unlawful deployment has continued resulting in substantial threat levels of possible chemical attack by international terrorists. This has led to an increased interest in the development of colorimetric sensors for the determination of these chemicals. Current methods of CWA verification are predominantly equipment-based and thus suffer from limitations including non-portability, high cost and complicated operations. Hence, there is high demand for inexpensive and lightweight colorimetric sensors that are simple to use for first responders. The development of sensitive and selective colorimetric devices for blister agents is investigated in this thesis. The first section of the thesis focuses on the development of sensors for mustard detection. Firstly, this research aimed to improve the mustard detection response of 4- (4-nitrobenzyl)pyridine (NBP) reported by Epstein. The incorporation of reagents in an anionic microemulsion eliminated the stepwise addition of reagents and the need for elevated temperatures. Exposure to various interfering agents revealed the high selectivity of NBP towards mustard simulants. Furthermore, the alkylation of NBP by anionic surfactant initiated an investigation into an alternative anionic surfactant to improve the shelf-life of the formulation. Furthermore, the preliminary research into self-assembled sensors for mustard detection was reported. An alternative merocyanine chromophore exhibited a moderate colour response upon exposure to CEES. However, the initial yellow-brown colour of the merocyanine in solution is undesirable and demonstrated the further work required to create a reliable analyte-induced sensor. The second section of the thesis presents the development of smart devices containing the NBP anionic microemulsion formulation, reported in Chapter 2, for use in real-life scenarios. Swab technologies were manufactured and tested with CEES alongside the detection of contaminated soil.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	31 March 2023
Last Modified:	31 Mar 2024 01:30
URI:	https://orca.cardiff.ac.uk/id/eprint/158262

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