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Systematic evaluation of the factors affecting LC-MS detection of some saponins and sapogenins associated with hepatogenous photo-sensitisation diseases in livestock, as determined using a Thermo Finnigan LCQ Advantage mass spectrometer, showed that ion responses could be substantially improved by careful selection of analysis parameters. Eluent composition, capillary temperatures and flow rate were found to significantly affect the ionisation of the target analytes. Optimisation of ionisation conditions resulted in a more than 100 fold (2 orders of magnitude) improvement in the detection of the model sapogenins and sapogenin glycosides relative to conditions utilised in previous studies at the University of Waikato. Optimal ESI and APCI responses were achieved using formic acid buffered acetonitrile-water eluent mixtures which posses...
The hypothesis that NIR might be capable of discriminating one floral source from another was explored. No prior analysis of NIR for New Zealand honeys has been reported. A visual inspection of the NIR spectra of ten New Zealand honey types indicates that beech honeydew honey is significantly different from nectar honeys. Rata honey is the most unique nectar honey with very little variability seen in the NIR spectra compared to other honey types. Both beech honeydew and rata honey can be distinguished from other floral types using Linear Discriminant analysis (LDA) on selected wavelengths. A degree of clustering within other honey types is achieved, however none of these are fully resolved. A Partial Least Squares (PLS) model successfully classified all main New Zealand unifloral honeys with an average correct classification of 93%. 10...
This thesis reports the mass spectral identification and characterisation of three new groups of algal compounds. A series of novel pectenotoxins (PTXs) were identified in retained sub-samples of Irish mussel extracts that had previously been utilised to obtain bulk quantities of some other algal toxins. The first eluting of the novel pectenotoxins, when analysed on a C-18 column using an MeCN-H2O gradient, afforded MNH4+ and MNa+ ions at m/z 864 and 869 respectively. This compound was designated as PTX-i. Three minor isomers (possibly storage artefacts) of the dominant PTX-i compound were also detected in the retained extracts, together with several later eluting sulfonated and sulfonated fatty acid ester analogues of PTX-i. The dominant fatty acid analogues were found to be the 16:0 esters. Sulfonated PTX-i isomers and their 16:0 fa...
Compound 1, which occurs in the flavonoid fraction of m??nuka honey and showed a statistical correlation with the non-peroxide antibacterial activity of the honeys, was extracted from fifteen kilograms of m??nuka honey using Amberlite XAD-2 resin and liquid-liquid extraction, and isolated by a combination of Sephadex-LH20 column chromatography and HPLC. Characterization of 1 was achieved by one and 2D- 1H and 13C NMR spectroscopy and GC-MS and 1 was identified as 2-formyl-5-(2-methoxyphenyl)-pyrrole. In addition to 1, two other non-flavonoids were isolated from the flavonoid fraction and their identities confirmed as caffeic acid and p-coumaric acid. Synthesis of 9 (3-hydroxy-1-(2-methoxyphenyl)-3-(oxazol-4-yl) propan-1-one), an intermediate in the route to 1, gave a yield of 67.5% as a pale yellow crystals after crystallization from C...
This investigation was carried out on behalf of the Momentive Specialty Chemicals Pty Ltd, Mt Maunganui. The aim of the investigation was to develop a method to analyse the formation of melamine formaldehyde resins via an in situ real time NMR experiment leading to quantitative NMR intensities of the resin up to the stages of its Industrial Resin Endpoint (IRE). In order to run an in situ reaction for the melamine formaldehyde resin system and monitor it in real time, both qualitative and quantitative NMR acquisition methods were required. The qualitative method was power gated and used to obtain results in situ and in real time. However to render it quantitative, it was necessary to develop a quantitative method which was initially executed to obtain a conversion factor for relating the qualitative results obtained in the in situ ex...
Since its arrival in New Zealand the clover root weevil (Sitona lepidus (syn. flavescens) (Coleoptera: Curculionidae) (CRW) has caused serious damage to New Zealand???s agricultural sector. The introduction of the biocontrol agent, Microctonus aethiopoides has caused a significant reduction in the population of CRWs. During their research on the CRW, AgResearch scientists discovered that the abdominal fat body and lipids present in the haemolymph in adult CRW varied with season, sex, insect age and parasitism. Parasitism has been reported to change the lipid composition of other species of insects. The purpose of the present study was to compare the chemical composition of the lipids present in parasitised and non-parasitised CRW adults, and determine how these lipids change with physiological state and parasitoid development. The ...
Veterinary antibiotics are used worldwide for prevention and treatment of various diseases of livestock animals. After administration, the majority of antibiotics are excreted in urine and faeces as unchanged parent compound, and/or as their metabolites. With increases in the intensive use of antibiotics in New Zealand agriculture and direct land application of waste as manure, there is concern that excreted compounds could migrate to the receiving environment with potential impact on surface and groundwater. Antibiotic residues in soil could give rise to a variety of ecotoxicological problems and could also confer antibiotic resistance. As a first step towards assessing the risk of these compounds, it is important to investigate their fate and behaviour in the soil environment. The focus of this work was to determine the fate and tran...
Nucleotides have been routinely supplemented to infant formulas due to the important roles they play in metabolism and to replicate the higher concentrations typically found in human milk. A method utilising anion exchange solid-phase extraction clean-up and liquid chromatography was developed for the rapid, routine determination of supplemented cytidine 5′ monophosphate, uridine 5′ monophosphate, inosine 5′ monophosphate, guanosine 5′ monophosphate, and adenosine 5′ monophosphate in bovine milk-based infant formula. Chromatographic analyses were performed using a C18 stationary phase with gradient elution, UV detection, and quantitation by an internal standard technique. A single-laboratory validation was performed, with recoveries of 92–101% and repeatability of 1.0–2.3%. An extension study demonstrated the expansion in scope to ...
As part of a detailed study of the nomenclature and taxonomy of the New Zealand species of Pseudocyphellaria it has been noted that the chemistry of the P. impressa (Hook & Taylor) Vainio aggregate, that is species with a markedly faveolate (honeycomb- like) upper surface and a green algal phycobiont, is particularly complex. The 45 lichen substances detected fall into four distinct groupings, here designated as 'Codings'. The aim of this contribution is to investigate suitable methods for revealing this chemical assemblage by t.l.c. and, as far as is currently possible, to identify the range of substances. No conscious attempt is made to assign the four chemical Codings to particular taxa or species groupings; the taxonomy of the group will be discussed elsewhere. The four Codings proved to be remarkably uniform and constant consideri...
Shellfish are considered a delicacy by many consumers. In NZ, as in many overseas countries, there is a now thriv¬ing shellfish industry servicing both domestic and inter-national markets. Periodically shellfish accumulate harm¬ful levels of a variety of algal toxins, including domoic acid, yessotoxins, pectenotoxins and brevetoxins. When this occurs, regulatory authorities may impose harvesting closures which have a consequential economic impact on both farmers and staff employed to harvest and market shellfish products.
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