by Ho Sing Yiu. / Thesis (M. Phil.)--Chinese University of Hong Kong, 1991. / Includes bibliographical references. / ACKNOWLEDGEMENT --- p.i / ABSTRACT --- p.ii / Chapter CHAPTER 1 --- GENERAL INTRODUCTION --- p.1 / Chapter PART I --- DERIVATIVE SPECT3ROPHOTOMETRIC METHOD FOR THE SIMULTANEOUS DETERMINATION OF COPPER AND NICKEL IN ALLOYS / Chapter CHAPTER 2 --- INTRODUCTION --- p.5 / Chapter CHAPTER 3 --- EXPERIMENTAL --- p.14 / Chapter CHAPTER 4 --- RESULTS AND DISCUSSION --- p.18 / Chapter PART II --- X-RAY FLUORESCENCE SPECTROMETRIC METHOD FOR THE SIMULTANEOUS DETERMINATION OF SEVEN METALS IN WATER SAMPLES / Chapter CHAPTER 5 --- INTRODUCTION --- p.43 / Chapter CHAPTER 6 --- EXPERIMENTAL --- p.58 / Chapter CHAPTER 7 --- RESULTS AND DISCUSSION --- p.65 / Chapter CHAPTER 8 --- CONCLUSION --- p.99 / REFERENCES --- p.101

published_or_final_version / Chemistry / Master / Master of Philosophy

Typewritten / Includes bibliographical references / 232 leaves ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1964

Thesis(MTech( Engineering))--Cape Peninsula University of Technology, 2012 / Platinum is a precious metal which may be processed under acidic conditions. Accordingly, the extraction of platinum from an acidic chloride media is of immense practical importance. In this study, the extraction of platinum was investigated in a Pt(IV)-HCl-Cyanex 921 matrix in order to establish the effect of temperature, extractant concentration, pH and the initial platinum concentration which had been used in the evaluated solvent extraction (SX) process. The extractant phase contained a mixture of Cyanex 921 and kerosene. In addition, the extraction mechanism of platinum, and the extracted species, are also described in the study, including the determination of the following: extraction ratio, extractant loading, distribution ratio, thermodynamic parameters, and the kinetic mechanism involved in the Pt(IV)-HCl-Cyanex 921 system used. Inductively coupled plasma emission spectroscopy (ICP-ES) was used to measure the platinum concentration in the aqueous phase with a mass balance being used to determine the concentration of platinum in the organic phase. Using a combination of the variables under investigation, the experiments which were evaluated indicated that it is possible to extract sufficient platinum chlorocomplex under the following conditions: pH of 1, Cyanex 921 concentration of 8% (v/v), temperature of 298 K and an initial platinum concentration of 55.22 mg/L. Under these conditions the maximum organic-phase loading of 253.9 mg/L was achieved as compared to the theoretical loading of 507.24 mg/L. The equilibrium loading of ~50% of the platinum chlorocomplex in the organic phase was achieved after 2400 seconds of reactor operation. In this case, a distribution ratio of 9.4 was achieved. This value was observed to be higher as compared to the other SX conditions evaluated in this study.

The carboxy terminal of the γ-chain of human fibrinogen contains at least three biologically. important functional domains: (i) the fibrinogen γ-chain polymerisation centre, (ii) the platelet receptor domain and (iii) the site for staphyloccocal clumping. The nature of the site specificity of these interactions necessitates the existence of a preferred conformation for this region, the nature of which has yet to be clearly established. A novel zinc metalloproteinase isolated from puff adder venom (PAV protease) capable of specifically cleaving the di-γ-chain of transglutaminase (Factor XIIIa) catalysed crosslinked plasmin derived D-dimer into apparently symmetrical monomers has been described. The activity is fibrin specific and displays an unusual site specificity for the γ-carboxy terminal domains within the crosslink region. The activity was reported to be potentiated by zinc. The effect of zinc on the digestion of D-dimer by PAV protease was evaluated by SDS-PAGE and by a fluorimetric technique utilising a fluorescent dansylcadaverine conjugate of the substrate (f-D-dimer). A differential zinc binding study determined that the potentiation of activity by zinc was due to a zinc-substrate rather than a zinc-enzyme interaction. The binding constant for zinc to D-dimer was determined by Scatchard analysis of zinc titration data. The interaction of zinc and f-D-dimer was confirmed by fluorescence anisotropy determinations. The nature of the coordination capsule around the metal cation was determined by examining a cobalt-fibrin-D-dimer complex and characterising the difference visible absorption spectrum thereof. The donor ligands from the D-dimer fragment for the metal ion were determined as histidines by examining zinc(II) and cobalt(II) binding to diethylpyrocarbonate modified fibrin-D-dimer and hydroxylamine treated DEPC-fibrin-D-dimer. Through this study it has been established that the PAV protease cleavage of the di-γ-chain of the plasmin derived D-dimer fragment is potentiated by zinc(II) ions through the formation of a novel zinc determined conformation of fibrin-D-dimer. This presents the possibility of a fibrinspecific neo-epitope being manifested in the presence of zinc ions that could provide a means to determine fibrin degradation products more specifically. A model for the neo-epitope has been proposed.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016. / The main purpose of this study is to understand the application of ion exchange chromatography on separation of charged ions of elements. Ion exchange chromatography is an analytical method, which is used for the separation of elements, quantitation and qualitation. The use of Amberlyst 15 resin as a source of separation for metal ions has been investigated and studies in various academic disciplines such as chemistry and material science. In this research study, Amberlyst 15 resin was investigated in order to understand the separation of positively charged divalent elements ions (Zn2+, Cu2+, Co2+ and Ni2+). The use of nitric acid and methanol mixture enhanced separation of these metal ions by ensuring that nitric acid is constant and varying methanol concentration. In this study, it was found that the resin has a high affinity for the metal ions at high methanol concentration, hence the distribution coefficient values increase but decreases at low methanol concentrations. The complexities of molecular structure of the salts of the elements provide the more understanding of the metal ion interaction with the resin particle. Furthermore, the role and strength of nitric acid to break the structural bonds and release the metal ions to get sorbed on the resin remains the most essential factor of understanding distribution coefficient values. Method validation parameters such as linearity, precision and accuracy of the method were determined. The method precision and accuracy were determined from the QC samples which is expressed as relative error (%RE) with the total coefficient of variation (%CV’s) were < 20%.

by Wong Chi Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 131-133). / Acknowledgement / Abstract --- p.1 / General introduction --- p.4 / Part I Determination of Some Minor Elements in Cement by Energy Dispersive X-Ray Fluorescence Spectrometry / Introduction --- p.7 / Experimental --- p.14 / Results and discussions --- p.18 / Part II Determination of Mercury in Water by Static Cold Vapour Atomic Absorption Spectrometry / Introduction --- p.78 / Experimental --- p.84 / Results and discussions --- p.89 / Conclusion --- p.130 / References --- p.131

Acid leaching of different natural chrysocolla samples under ambient conditions demonstrated that the chemical and chrystallographic inhomogenity significantly affects the rate and that it is virtually impossible to use the mineral as a model for the kinetics of hydrometallurgical processing of copper ores.Dissolution experiments, stability diagrams,and X-ray powder diffraction studies are undertaken and studied in this research and results are given.It is found that a complete solid solution series exists in Nature with most tungstenian wulfenites and molybdenum stolzites containing a range of compositions. The first occurrence of a molybdenum stolzite from Broken Hill, Australia, which also contains small amounts of chromium is noted.Raman microprobe spectroscopy has proven to be a very quick and effective non-destructive method for semi-quantitative analysis of the wulfenite-stolzite and powellite-scheelite solid-solution series and in detecting very small amounts of substituted chromate in wulfenite, stolzite and anglesite / Doctor of Philosophy (PhD)

Electrochemical methods were researched for the analysis of metals, proteins and the identification of metal binding proteins. Adsorptive cathodic stripping voltamrnetry for metal analysis combines the inherent sensitivity of electrochemical techniques with the specificity of ligands for the nonfaradaic preconcentration of analytes at the electrode. The utility of catechol, resorcinol, 4-methylcatechol and 4-t-butylcatechol as ligands was explored for the sensitive analysis of copper, bismuth, cadmium and lead on a mercury film glassy carbon electrode. Metal complexes of lead, copper and bismuth with resorcinol showed the largest increase in current with increase in metal concentration, whereas complexes of these metals with 4-t-butylcatechol showed the lowest current response. Cadmium showed the highest current responses with 4-methylcatechol. The four metals could be determined simultaneously in the presence of resorcinol, although considerable interference was observed between bismuth and copper. The electroanalysis of cysteine and cysteine containing proteins at carbon electrodes are impaired by slow electron transfer rates at carbon electrodes, exhibiting high overpotentials, greater than 1 V vs Ag! Agel. Metallophthalocyanines have been shown to promote the electrocatalysis of cysteine at lowered potentials. Chemical modification of electrodes with appropriate modifiers is a means of incorporating specificity into electroanalysis, with applications in electrocatalysis. A glassy carbon electrode was modified by electrodeposition of cobalt (II) tetrasulphophthalocyanine [Co(II)TSPct to produce a chemically modified glassy carbon electrode (CMGCE). The CoTSPc-CMGCE catalysed the oxidation of cysteine in the pH range 1 to 10. The significance of this electrode is an application for analysis of proteins at biological pH's. A biscyanoruthenium(II) phthalocyanine CMGCE catalysed the oxidation of cysteine at 0.43 V vs Ag/AgCl a significant lowering in the overpotential for the oxidation of cysteine. Metallothionein, a metal binding protein, is believed to be involved in metal homeostasis and detoxification in the peripheral organs of living systems. A method for the quantitative determination of this protein utilising its high cysteine content was presented. At pH 8.4 Tris-HCl buffer, and using a CoTSPc-CMGCE modified by electrodeposition of the modifier, the anodic peaks for the oxidation of metallothionein was observed at 0. 90 V vs Ag/ AgCI. Ferredoxin is a simple iron-sulphur protein. One tenth of its residues are cysteine. Ferredoxin is involved in simple electron transfer processes during photosynthesis and respiration. Electrochemical studies of spinach ferredoxin were conducted at a CoTSPc-CMGCE. Anodic currents for the oxidation of the cysteine fragment of ferredoxin was observed at 0.85 V vs Ag/AgCl in HEPES buffer at pH 7.4, representing a new method for analysis of this protein. Voltammetric studies of its ferric/ferrous transition have shown quasi-reversible waves atE~ -0.62 V vs Ag/AgCl only in the presence of promoters. At a CoTSPc-CMGCE, a cathodic wave attributed to the reduction of Fe(III)/Fe(II) was observed at Epc -0.34 V vs Ag/AgCl. This represents an alternative method for voltammetric studies of the ferric/ferrous transition at significantly lowered potentials. Melatonin, a pineal gland hormone functions m setting and entraining circadian rhythms and in neuroprotection as a free radical scavenger and general antioxidant. Using adsorptive cathodic stripping voltammetry, the binding affinities of melatonin, serotonin and tryptophan for metals, were measured. The results showed that the following metal complexes were formed: aluminium with melatonin, serotonin and tryptophan; cadmium with melatonin and tryptophan; copper with melatonin and serotonin; iron (III) with melatonin and serotonin; lead with melatonin, tryptophan and serotonin, zinc with melatonin and tryptophan and iron (II) with tryptophan. The studies suggest a further role for melatonin in the reduction of free radical generation and in metal detoxification and may explain the accumulation of aluminium in Alzheimer's disease.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND LINDGREN / Bibliography: leaves 209-226. / by Harlan Wheelock Stockman. / Ph.D.