Dissertation

The utilization of liquid chromatography tandem mass spectrometry and related techniques for the analysis and identification of emerging contaminants in aqueous matrices

Reichert, Matthew

2016

Overview

Environmental pollutants can be found in many ecosystems and cover many different compound classes. The Environmental Protection Agency is responsible for monitoring and regulating several of these classes of compounds which daily enter the environment. However, there are still hundreds, if not thousands, of compounds present in the environment which have yet to be regulated or even identified. The discovery and identification of these unknown emerging pollutants is crucial for the prevention of potential human health risks and irreversible ecological damage. The research presented is divided into two projects. The first part of this research investigates the disinfectant 3-Bromo-1-chloro-5,5-dimethylhydantoin, which is often used in the treatment of hot tubs. Treating the water with this chemical is intended to protect the swimmer from harmful bacteria that may be present in the water. However, the reaction of the disinfectant with other organic compounds found in the water can lead to the formation of potentially toxic disinfection by-products. The use of thermal desorption negative chemical ionization time-of-flight mass spectrometry allows for a wider range of compounds to be ionized than conventional gas or liquid chromatography. The high resolution mass data were used to infer a molecular formula that could be used in database searches to find potential structural matches. The mass spectra indicated the presence of ions containing one and two bromine atoms. The second study investigated the oxidation of the prevalent environmental contaminant triclosan. Triclosan is known to oxidize to form 2,4-dichlorophenol, which is carcinogenic and displays some estrogenic activity. While other oxidation products have been hypothesized, such as other dichlorophenols, none have been positively identified. Analysis of reactions of triclosan and hydrogen peroxide at high pH indicate the presence of three compounds that appear to all be dichlorophenols. One compound has been identified as 2,4-dichlorophenol. Additionally, 2,5-dichlorophenol and 3,4-dichlorophenol have been identified. A late eluting peak has fragmentation consistent with the dichlorophenols. However, it does not coelute with the dichlorophenol standards. This compound is hypothesized to be a semi-quinone. The effects of pH on the oxidation product profile of triclosan are also presented.

• Publisher: ProQuest Dissertations & Theses
• Subject: Analytical chemistry / Chemistry / Environmental science
• ISBN: 1369573472, 9781369573473