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    The analytical geochemistry of platinum group metals in cretaceous/tertiary boundary clays : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in chemistry at Massey University
    (Massey University, 1991) Wilson, Shane Malcolm
    The Cretaceous tertiary boundary controversy is discussed. The importance of the platinum group metals (PGM) as markers of extraterrestrial material in sediments is explained. The use of inductively coupled plasma source mass spectroscopy (ICP-MS), and graphite furnace atomic absorption spectroscopy (GF-AAS), to determine PGM in geological materials, was investigated. Both techniques require the analyte to be substantially separated from the geological matrix before instrumental analysis is performed. Separation schemes involving fire-assay, ion exchange chromatography, solvent extraction, and coprecipitation, were investigated. A standard ore (PTC- 1) was successfully analysed for Rh and Pd using a separation scheme involving Te coprecipitation followed by dissolution and determination by ICP- MS . The same ore was successfully analysed for Pd using GF-AAS after a separation procedure involving solvent extraction of a Pd-ammonium pyrrolidine dithiocarbamate complex. Sedimentary rock samples were collected from a newly discovered K/T boundary site (Flaxbourne River) in New Zealand. Determinations of Pd in Flaxbourne River sediments were made using GF-AAS after matrix separation using solvent extraction. Elevated levels of Pd at the K/T boundary were found contiguous with elevated levels of Ir. Besides these PGM, a further twenty elements were determined in Flaxbourne River K/T boundary sediments. The results of this geochemical survey are discussed with respect to the impact and volcanism theories (theories which seek to explain the palaeontological, geochemical, and geological changes occurring at the K/T boundary).
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    The platinum group metals in iron meteorites : thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry, Department of Chemistry and Biochemistry, Massey University, Palmerston North, New Zealand
    (Massey University, 1990) Hoashi, Maki
    Solvent extraction methods have been developed for the determination of Ru, Pd and Pt in iron meteorites. The method for Ru is based on the oxidation of this element in HCl solutions with sodium periodate followed by extraction of the tetroxide into CHCl3. The CHCl3 phase is then removed to a HNO3-NaIO4 "keeper" solution for storage up to 17 hours prior to analysis. The method for Pd and Pt entails simultaneous extraction of their stable iodocomplexes into methylisobutyl ketone after removal of Fe(III) as the chlorocomplex. The digestion of the samples with reference to these elements has also been investigated. All three elements were determined by the graphite furnace atomic absorption spectrometry technique. The limit of detection was lowered by increasing the volume of organic phase placed in the graphite furnace. The lowest absolute detection limits achieved in this study were 0.5 ng for Ru, 0.5 ng for Pd and 5 ng for Pt. The platinum group metal values for 108 authentic iron meteorites were subjected to Principal Components Analysis and Discriminant Analysis. These procedures confirmed the validity of the classification of iron meteorites developed over the past 25 years, but highlighted poor fits for some individual iron meteorites within a group. Possible reclassification of these members was evaluated after consideration of the meteorite's morphological features. The cases for the merging of some groups were investigated and discussed with reference to the chemical features of those groups. The data obtained also revealed several cases of meteorite pairings (related members of a single meteorite shower catalogued as separate meteorites), instances of the mislabelling of museum fragments and two putative meteorites which proved to consist of man-made materials.