This thesis is concerned with the preparation of regiospecifically labelled compounds by homogeneous metal catalysed hydrogen isotope exchange reactions. The features of homogeneous hydrogen isotope exchange reactions are discussed in Chapter 1, along with other exchange methods; acid, base, heterogenous metal, radiation, enzymic and zeolite catalysis. In Chapter 2, homogeneous rhodium trichloride is investigated for regiospecificity of tritium labeling in a wide range of aromatic compounds. High regiospecificity of labelling ortho to carboxyl, carboxamide and methanamide groups is found, with the regiospecificity determined by 3H nmr spectroscopy. Also discussed is a study to determine whether any other Group VIII metal complexes will catalyse the ortho tritiation of benzoic acid, in addition to rhodium trichloride. The results of detritiation studies performed on benzoic acids using ruthenium acetylacetonate as catalyst as a model for rhodium trichloride are presented in Chapter 3, A possible reaction mechanism is also presented. Finally, an application of the rhodium trichloride system to the labelling of biologically useful molecules is discussed in Chapter 4. The deuteration and tritiation of a number of drugs and metabolites containing known ortho directing groups is described. In a large number of cases, the regiospecificity for ortho labelling is very high.

The field of quadrupole mass spectrometry has grown enormously since the early 1980's. The invention of the triple quadrupole mass spectrometer led to the development of tandem quadrupole mass spectrometers of many different configurations. A large number of tandem quadrupole mass spectrometers have also been developed by linking one or more quadrupole mass filters to a traditional magnetic or electric filter. The versatility of multiple quadrupole mass spectrometers along with their potential to rapidly produce a huge amount of data on a particular ion makes them ideal instruments for routine analytical analysis as well as for fundamental research The quinquaquadrupole mass spectrometer has been developed as an extension to the available multiple quadrupole systems. It offers the possibility to obtain even more data on the fragmentation of ions as well as enabling the study of novel ions to be carried out. The development of the quinquaquadrupole mass spectrometer forms the main part of this thesis. Also discussed are the reactions studied to evaluate the instrumental performance. The the ion molecule reactions of some halogen containing cations with saturated and unsaturated hydrocarbons performed on the triple quadrupole mass spectrometer are also discussed.

Intermolecular energy transfer occurs between Tb(aa)3.3H20 and Ln(aa)3.3H2O complexes (Ln = Pr, Nd, Sm, Eu, Dy, Ho or Er; aa = acetylacetonate) in n-butanol solution at 293K. Measurement of the decay time of the Tb3+ 5D4level indicates that transfer occurs from this level to excited levels of the Ln3+ ions with bimolecular rate constants within the range 0.5 - 4.9 x 105 dm3 mol s −1. Data from similar measurements on a mixed crystal EuxTb(1-x)(aa)3.3H2O and other considerations indicate that this is a very short range electron-exchange transfer. Similar measurements of the Tb3+ ion phosphorescence yield indicate the presence of a further intermolecular transfer process between a higher excited state of the Tb3+ complex and the added Ln3+ complexes. The Stern-Volmer Quenching constants vary from 11 dm3 mol−1 for Ho and Sm to 110 dm3 mol−1 for Pr. It is concluded that this transfer is unlikely to occur from either the ligand singlet or triplet levels and it is proposed that a higher Tb3+ level such as the 5D3 may be involved in both inter- and intramolecular energy transfer. Intermolecular energy transfer between excited state Tb3+ ions in Tb(aa)3.3H2O and Ln3+ ions in Ln(aa)3.3H2O, where Ln = Eu and Sm, is shown to be markedly solvent dependent. It is proposed that the Tb3+ → Ln3+ energy transfer occurs in mixed metal dimers where the Tb-Ln distance is likely to be ca. 0.4 nm. The solvent dependent behaviour is related to the relative concentrations of monomeric and dimeric species in the various solvents. The rate controlling step in the intermolecular energy transfer is probably that, of monomer-dimer reaction which at 273K is of the order of 105 dm3 mol−1 s−1. The activation energy of this reaction between Tb, Eu and Sm acetylacetonates is estimated to be ca. 23 kJ mol−1. 1H NMR spectra of Lu(aa)3.2H2O in several solvents are reported. The spectral profiles are temperature dependent in benzene and toluene solutions and the multiplicity of ligand methyl resonances is attributed to slow exchange between non-equivalent methyl groups in a dimeric structure. The temperature dependence in acetone solution is consistent with the presence of a monomer-dimer equilibrium with △H° = -28.2 ± 1.5 kJ mol−1 and △S° = -74.5 ± 4.5 J K −1 mol−1. The single ligand-methyland 3-H resonances in the' strongly coordinating solvents dimethyl sulphoxide and pyridine indicate the sole presence of solvated monomers. Previous proposals about the anomalous spectrum of Mg(aa)2 in CDCl3 are also discussed. The extremely low efficiency of the intermolecular enrgy transfer process in europium acetylacetonate compared with the corresponding terbium acetylacetonate is attributed to the presence of a charge-transfer excited state lying below the ligand singlet states. This is supported by the anomalous absorption spectrum of the Eu3+complex and the effects of added anions in other ligand systems. The phosphorescence spectra of the Group I and Group II metal acetylacetonates (Metal = Li, Na, K, Rb, Gs, Mg, Ca, Sr and Ba) have all been measured in solid Ethanol glass solutions at 77K and found to have profiles similar to that of Al(aa)3. The phosphorescence decays are non-exponential and this behaviour is attributed to the presence of both coordinated and free acetylacetonate anion. Time resolved spectroscopy and other considerations indicate that the energies of the lowest excited ligand singlet and triplet states of the aa− ion are, unlike the triplet state lifetime, little affected by coordination. Solvolysis is reported in ethanol solution which invalidates some previously-reported spectral parameters.

The principal objective of the research was to model the outflow results of multiple tracer outflow dilution (M.T.O.D.) techniques from the canine tibia so as to obtain a more precise understanding of the physiological mechanisms underlying mineral exchange in bone. To date, M.T.O.D. techniques have been performed on the tibiae of greyhound dogs but the subsequent outflow results have produced information mainly at the capillary level for the diffusible tracers concerned such as capillary permeability-surface area PSC products from the widely used Crone-Renkin formulation. Back diffusion and heterogeneous capillary flow rates lacking from the formulation, however, have impaired the accuracy of PS(C). Outflow results from two series of previously performed M.T.O.D. experiments were modelled. In the first experimental series, outflow results from the ipsilateral femoral vein concerning l25l-albumin reference and 85Sr (Ca analogue), 86Rb (K analogue) diffusible tracers were used ; the tracers having being injected into the tibial nutrient arteries. In the second experimental series, 125l-albumin and 85Sr outflow results were used from parathyroidectomised dogs in which both tracers had been injected together before and after a dose of 0.0005 mg bovine parathyroid hormone (PTH). The problem of back diffusion was alleviated by optimising a homogeneous flow model to M.T.O.D. data. The model produced informative parameter estimates for 85Sr and 86Rb concerning fluid spaces and associated boundaries in Haversian systems largely comprising the diaphyseal cortex. Exchange was assumed to take place there by virtue of injecting the tracers into the tibial nutrient artery. Blood flow rates, known to be influential in governing the extent of tracer exchange in the diaphysis, were investigated using the microsphere technique. Flow rate heterogeneity was found to be substantial, as adjudged by distributions of relative deposition densities of microspheres in 40 pieces of cortex and 10 marrow samples in 6 tibiae. For the cortex, the distributions were positively skewed with a relative dispersion of around 40%. Additional work involving light microscopy suggested that the distribution of cortical flow rates were not attributable to particular changes in capillary density, which were relatively uniform at 2682 + 510 capillaries/cm2 (4 tibiae ; 240 observations). The findings concerning flow rate heterogeneity, together with the deduction that the cortex and marrow respectively received 65% and 35% of tibial nutrient artery flow, prompted the development of a parallel multicapillary model in which 4 capillary systems were alloted to the cortex and 1 such system to the marrow. Input to the model was a suitable form of the reference tracer outflow profile which describes the large vessel transport behaviour assumed identical for all tracers concerned. Parameter estimates (mean + s.d.) found by optimisation for 85Sr and 86Rb (n=6) were PSC = 0.045 + 0.021 and 0.047 + 0.022 ml/s respectively. Apparent volumes of distribution (n=5) for the interstitial fluid were 0.90 + 0.36 (85Sr) and 0.69 + 0.22 ml of diaphysis (86Rb). Additional studies involving gamma variates showed that model inputs were robust in terms of varying degrees of large vessel dispersion. Furthermore, simulation studies involving the effect of asymmetric transport on the resulting parameter estimates in the context of modelling the PTH data provided speculative evidence for the concept of a bone-lining cell membrane controlling uptake to bone surfaces.

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Thesis (MTech (Electrical Engineering))--Peninsula Technikon, Cape Town, 2002 / The problem for wastewater treatment is very important these days because of population increase and industry development. Ion exchange technology has proved its positive qualities in domestic lives and industry, but the ion exchange process still needs deeper understanding and improving. That is why a new pilot plant has been built in Chemical Engineering Department at Peninsula Technikon. In addition to the treatment of domestic effluents there are other processes which the ion exchange is suited for, such as the recovery and the reuse of industrial effluents. The proposed control system is developed in such a way that it does not have to depend on a certain effluent. The selection of the process and the development of techniques for its control fall into the national needs of improving people's lives (e.g. giving them excess to clean water) and quality of the environmental conditions (treatment of toxic waste substances). There is a need for an application area for modeling and control methods developed in the field of control engineering for the Department of Electrical Engineering; on the other hand a need of control techniques for the development in the Department of Chemical Engineering technological process. This multidisciplinary liaison between the two Engineering departments promotes joint research activities and relevance between them. It also equips the graduating engineer with the relevant experience into working in a team of multidisciplinary engineering fields.Community and industrial relevance of the research study is that in addition to treatment of domestic effluents, the ion exchange process is also particularly well suited for: the desalination of hard waters, combined neutralization and desalination of alcohol effluents, such as mine drainage, acid mineral tailings, paper bleach affluent. the pretreatment of reverse osmosis feed for the removal of organic and colloidal particulate.

Thesis (MTech(Chemical engineering))--Cape Technikon, Cape Town,1996 / Metal cyanide complexes are a toxic pollutant in waslewater originating from various industrial and mining activities. The removal/retrieval ofcyanide and metal cyanide complexes has been studiedby researches for many years, leading to the establishment of a variety of patents. The mechanisms used by these patents vary from purely chemical techniques to those using ion exchange Iesins. In this thesis, ,the feasIbility ofthe recovery ofmetal cyanide complexes by using a strong base macroreticular resin, in a fluidized bed configuration, has been investigated. The resin in question is presently used in the sugar indnstry where its main application is the recovery oflarge organic molecules similar in nature to metal cyanides. The selected resin was contacted with synthetic solntions of various metal cyanide complexes. for the purposes of evaluating performance in the adsorption th..."feOf. It was found that polyvalent metal cyanide molecules were adsOlbed efficiently, while divalent metal cyanide molecules were adsorbed satisfactorily. The loaded resin was also evalnated for the ease with which the metal cyanides conId be removed. It was discovered that a brine solntion ofpH 7, conId effectively remove all metal cyanide complexes. This test-work was of particular importance as it is well !moon that the removal ofmetal cyanides from strong base metals is not easily achieved. To distingnish the fluidization characteristics of the selected resin (or any resin for that matter), a method of modelling the expansion of a flnidized resin bed was proposed, that takes into account the diflicnIties associated with the byclrod:)nantic charncteristics of a macroporous resin of this nature. The technique is based on the Serial Afadel which is a discretised application of the Z3ki and Richardson equation. From the interpretation of the resnIts of a matrix of fluidization tests, it was fonnd that the algorithm proposed conId effectively model the expansion of a fluidized bed of ion exchange resin, independently of the dimensions ofthe accomodatiog receptical. Finally. it was shown that the change in the fluidization characteristics of the selected resin, between its chloride and metal cyanide states, could clearly be modelled by the technique referred to above.

Thesis (MTech (Chemical Engineering)--Cape Technikon, Cape Town,1996 / Acetylene Black IACB) IS a pure form of carbon which is used in the battery, plastics, printing and rubber industries. It is extensively used in the battery industry to absorb electrolyte and to lower the electrical resistance of dry cell batteries. It is the attempt of this thesis, to investigate the surface characteristics '---------._-- -,- ...• -...•--- .. ------.. _.. --- "'- and structure of ACB by using it as an adsorbent for cyanide complexes, in particular gold cyanide. The thesis is predominantly aimed at identifying the mechanism of metal cyanide adsorption onto ACB, viz. ion exchange and/or physical adsorption. In order to quantify the mechanism of adsorption, comparative studies with other adsorbents currently used in the mining industry, such as activated carbon, were conducted. These studies revealed various similarities in the metal adsorption process between ACB and activated carbon, thus indicating physical adsorption rather than ion exchange to be the dominant mechanism for metal adsorption from solution. The rate of metal adsorption onto acetylene black was relatively fast compared to activated carbon. Furthermore, adsorption profiles revealed that intraparticle diffusion was negligible when a metal was adsorbed onto ACB from solution. This indicates that acetylene black has a predominantly amorphous structure, although X-ray diffractrometry indicates a certain degree of graphitisation associated with ACB. The small surface area of ACB, together with the lack of intraparticle diffusion, resulted in the rapid attainment of the equilibrium metal loading on ACB. Moreover, this equilibrium metal loading was far less than that of activated carbon and ionexchange resin. While pH, temperature and strong oxidizing agents had a marked effect on the adsorption profile of metal cyanides onto ACB, the effect of oxygen enrichment and organic solvents was negligible. Furthermore, the adsorption of gold onto ACB is best explained by a Freundlich-type isotherm. As is the case with activated carbon and ion exchange resin, gold is eluted from ACB by a NaOH solution. It was also found that the elution efficiency is influenced by a change in temperature. Changes in operating variables in the production of ACB had an effect on the absorption stiffness of the product. Both an increase in acetylene feed rate and operating temperature reduced the absorption stiffness of the product.

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