Date of Award

2005

Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Dr. Kevin J. James

Abstract

The impact of phycotoxins on human and animal health is of important concern for worldwide authorities and the scientific community. Domoic acid (DA) is a neurotoxin produced by phytoplankton {Pseudonitzchia spp.). It enters the food chain through the consumption of shellfish that feed on toxic diatoms. DA has been responsible for several outbreaks affecting humans and animals all around the world. Yessotoxin (YTX) is produced by dinoflagellate species {Protoceratiuni reticulatum) which are globally distributed. Its toxicity is low when ingested orally. However, the co-extraction of YTX with diarrhetic shellfish poisoning (DSP) toxins, derives false positives when the mouse bioassay is employed in monitoring programmes. This causes unnecessary closures of shellfish production sites that could be avoided if toxin levels were monitored using analytical methods.

Liquid chromatography-mass spectrometry (LC-MS) techniques have been developed over the last 20 years, and the study of marine biotoxins has benefited through its application. Among the mass spectrometers available at present, three MS were used in the studies presented here, namely triple stage quadrupole (QqQ), quadrupole ion trap (QIT) and time-of-flight (TOP). All mass spectrometers combine ion formation, mass analysis, and ion detection. Each mass analyzer has its own special characteristics and applications. The capabilities of each instrument complement each other, and together allow more complete knowledge of the analyte, in this case the marine biotoxins, DA and YTX.

One of the main difficulties that has to be overcome for the development of instrumental techniques, is the lack of reference material. In this thesis an isolation protocol was developed in order to provide purified and semi-purified DA and three of its isomers from contaminated scallops {P. maximus). The isolates were characterised by 'H NMR and mass spectrometry. LC-UV and LC-MS methods were developed for the rapid and quantitative determination of DA, YTX and some of their analogues in both phytoplankton and shellfish.

Access Level

info:eu-repo/semantics/openAccess

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