Development and Application of Analytical Methods for Marine Toxins
|dc.contributor.author||McNabb, Paul Simon|
|dc.identifier.citation||McNabb, P. S. (2014). Development and Application of Analytical Methods for Marine Toxins (Thesis, Doctor of Philosophy). University of Otago. Retrieved from http://hdl.handle.net/10523/4594||en|
|dc.description.abstract||Shellfish accumulate marine toxins from their microalgal diet. The marine toxin tetrodotoxin (TTX) also accumulates in seafood, but via unknown mechanisms. Toxin determinations have traditionally been performed using live mouse bioassay. Due to ethical concerns and the poor analytical performance of these assays, alternatives are needed. During the present study, an LC-MS method for determining six brevetoxins was validated. The recovery ranged from 73% to 112% for most analytes and was 61% for one (PbTx-2). The within lab reproducibility ranged from 14% to 18% for most analytes except PbTx-2, which gave a value of 27%. The sum of the concentrations for all six brevetoxins, when compared to the mouse bioassay, appears to be a conservative measure of toxicity. A receptor binding assay (RBA) was also investigated as a replacement of the paralytic shellfish poisoning mouse bioassay. The assay was subjected to inter-laboratory testing and three spiked samples gave a recovery of 84% to 93% with reproducibility of 29%. Compared to HPLC alternatives, the RBA assay has the advantage of presenting results in a total toxicity format without the need for quantitation of each toxin and the application of toxin equivalence factors. Positive mouse bioassay results were commonly reported for Crassostrea gigas samples from Rangaunu Harbour, Northland, NZ prior to 2000 and have been attributed to the presence of Rangaunu Harbour Toxin (RHT). The nature of this toxin was further investigated using an LC-MS assay in light of the discovery of pinnatoxins (PnTxs) in C gigas from Australia. An LC-MS method was validated, and PnTx recovery ranged from 79% to 81% with reproducibility from 5.8% to 9.8%. Nine samples of C gigas collected between 1993 and 1995 and two samples collected in 2008 were tested for PnTxs using this new LC-MS assay method. All samples were found to contain PnTxs but no other toxins and so it was concluded that RHT is PnTx. A survey of the health of locals consuming shellfish from the area over many years suggested that PnTxs are of no concern for human health. Two LC-MS methods were developed and validated for the detection and quantification of TTX. One relied on direct quantitation of TTX after HILIC chromatography and the other method determined TTX after reaction with NaOH to form the C9 base. The recovery for the direct method at 1 mg TTX/kg was 94% to 120% and RSDR ranged from 9% to 27%. The C9 method demonstrated a recovery of 105% to 109% and RSDR ranged from 17% to 19%. TTX was found in four species during a year-long monitoring programme: Pleurobranchaea. maculata , Astrostole scabra, Crassostrea gigas and Paphies australis. Studies into the source of TTX revealed that TTX concentrations in P. maculata decrease at approximately the same rate in the wild and in aquarium. Feeding studies suggested that TTX could be acquired by P. maculata from their diet.|
|dc.publisher||University of Otago|
|dc.rights||All items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.|
|dc.title||Development and Application of Analytical Methods for Marine Toxins|
|thesis.degree.name||Doctor of Philosophy|
|thesis.degree.grantor||University of Otago|
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