Date of Award

2014

Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Prof. Kevin J. James

Second Advisor

Dr. Ambrose Furey

Abstract

Cyanobacteria, also known as blue-green algae, are a common component of many freshwater and marine ecosystems and have a potential to produce several different classes of biotoxins. The most common class of cyanobacterial toxins are the microcystins (MCs) and cylindrospermopsins (CYLs). MCs are cyclic heptapeptides that display potent hepatotoxicity and are tumour promoters. CYLs are alkaloids that are cytotoxic and can cause illness and display hepatotoxic effects in animals and humans. Worldwide, these toxins have caused fatal poisonings to animals, birds and fish. Several incidents of human intoxications have been reported and the presence of these toxins in environmental waters that are used for the production of potable waters is of big interest to the drinking water treatment industry.

Traditionally, prior to the analysis of MCs and CYLs, lengthy sample preparation procedures have been required. Solid phase extraction (SPE) is the most commonly used procedure for sample preparation and analyte pre-concentration. These SPE methods are often extremely tedious, lengthy and expensive to carry out, offer variable rates of recovery for MCs, require large amounts of organic solvents and require a lot of operator know-how in the successful day to day operation of methods. In this thesis, automation and the sensitivity of automated and hybrid instrumentation has been exploited to develop rapid and sensitive methods for the analysis of MCs and CYLs in environmental freshwaters. During these studies, an automated analyte preconcentration method with liquid chromatography - tandem mass spectrometry (LC- MS/MS) was developed using triple quadrupole mass spectrometry for a number of MCs. In addition, the features of new hybrid instrumentation were exploited and direct methods were developed using full scan orbitrap mass spectrometry for a suite of MCs in environmental freshwaters. The mass fragmentation pathways of MCs were investigated using high resolution mass spectrometry and the use of desmethylated standards allowed for the reassignment and correction of previously published proposed product ion assignments.

Two more direct methods were developed for the analysis of CYLs in freshwaters using linear ion trap and full scan Orbitrap MS, in both negative and positive ionisation modes as CYL is zwitterionic. In addition, the mass fragmentation pathways of CYLs in both ionisation modes were studied using LIT MS" studies and high mass accuracy data generated using the Orbitrap MS.

Comments

Supervised by: Prof Kevin J. James and Dr. Ambrose Furey

Co-supervised by: Prof John O’Halloran and Dr. Frank van Pelt

Access Level

info:eu-repo/semantics/openAccess

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