Orientador : Pedro Faria dos Santos Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-07T19:57:18Z (GMT). No. of bitstreams: 1 Dantas_JosivaniaMarisa_M.pdf: 785971 bytes, checksum: 956ebcdc7258f32b05a05a39e08b2596 (MD5) Previous issue date: 2006 / Resumo: A análise sistemática de cátions é uma prática comum nos laboratórios de Química Analítica tanto na análise qualitativa realizada no meio acadêmico quanto na indústria, na identificação dos mais diferentes tipos de amostras desconhecidas. Esta prática é fruto de um vasto conhecimento de química acumulado de décadas por inúmeros pesquisadores e cientistas que conheciam a reatividade de muitas classes de compostos orgânicos e inorgânicos, bem como a propriedade de muitos deles. Em termos de ilustrar os métodos básicos de separação e identificação de íons, esta análise atinge seu objetivo. Contudo, não se conhece até o presente, nenhum texto que discute os conceitos químicos envolvidos em cada uma das etapas de separação e identificação de cátions. Neste trabalho foi elaborado um material didático para ser utilizado por alunos das várias modalidades dos cursos de Química. Nele foram enfatizados os fundamentos, conceitos e teorias envolvidos em cada um dos métodos explorados na análise sistemática de cátions. A produção deste material complementar aos já existentes não implica, de forma alguma, substituir o material utilizado atualmente. Para isto é utilizada a mesma divisão em grupos de cátions, apresentada em livros de Química Analítica Qualitativa. O material didático elaborado foi aplicado nas aulas desta disciplina no Instituto de Química da Unicamp e os resultados foram coletados por meio de questionários, participação e observação nas aulas / Abstract: The systematic cations analysis is a common practice in analytical chemistry laboratory for undergraduate students and also at the industry, for identification of different kinds of unknown samples. This practice is a result of a vast knowledge in chemistry acumulated during decades by researchers and cientists who knew the reactivity of several classes of organic and inorganic compounds, as well as its properties. In order to show the basic methods of ions identification and separation, this systematic analysis attain the desired objective. However, it is not known so far any text that discuss the chemistry concepts that relates the stages of cations separation and identification. In this work a didactic material was elaborated for undergraduate students, emphasiting the fundaments, concepts and theories involved in each one of the methods of systematic cations analysis. This supplementary didactic material was created in order to improve the currently used material. The same division of cations groups presented in the qualitative analytical chemistry books was mantained. The elaborated didactic material was applied in classes of this subject at Chemistry Institute of Unicamp and the results were collected by means of questionnaires and also classes participation and observation / Mestrado / Quimica Analitica / Doutor em Quimica

Thesis (MSc)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The equilibrium distribution coefficients of 42 elements [Li(I), Na(I), K(I), Rb(I), Cs(I), Sc(III), Ti(IV), V(IV), V(V), Mn(II), Fe(III), Ni(II), Zn(II), Al(III), Ga(III), As(V), Y(III), Zr(IV), Nb(V), Mo(VI), Cd(II), In(III), Sn(IV), Sb(V), Ta(V), W(VI), Pb(II), Bi(III), La(III), Ce(III), Th(IV), U(VI), Co(II), Ag(I), Ge(IV),Mg(II), Sr(II), Ba(II), Tb(III), Yb(III), Cr(III) and Cu(II)] on Bio Rad AG MP-50 macroporous cation exchange resin in varying citric acid – nitric acid mixtures were successfully determined. The equilibrium distribution coefficients of these selected elements were determined in 0.1 M and 0.25 M citric acid at various concentrations of nitric acid, namely, 0.2 M, 0.5 M, and 1.0M, respectively. Two component [Mo(VI)-Y(III); Zr(IV)-La(III) and As(V)-Zn(II)] and three component [Nb(V)-Ta(V)-V(V)] elemental separations on a 10 ml AG MP-50 resin column were successfully determined to illustrate how the results of the above equilibrium distribution coefficients can be utilised. From the equilibrium distribution coefficients obtained for magnesium(II) and sodium(I), a proposal was put forward to modify the current sodium-22 production performed at iThemba LABS. While the results did not predict a possible separation between the two elements, a theory concerning the use of citric acid in the production was proven not to hold under the chosen conditions. / AFRIKAANSE OPSOMMING: Die ewewig verdelingskoëffisiënte van 42 elemente [Li(I), Na(I), K(I), Rb(I), Cs(I), Sc(III), Ti(IV), V(IV), V(V), Mn(II), Fe(III), Ni(II), Zn(II), Al(III), Ga(III), As(V), Y(III), Zr(IV), Nb(V), Mo(VI), Cd(II), In(III), Sn(IV), Sb(V), Ta(V), W(VI), Pb(II), Bi(III), La(III), Ce(III), Th(IV), U(VI), Co(II), Ag(I), Ge(IV),Mg(II), Sr(II), Ba(II), Tb(III), Yb(III), Cr(III) en Cu(II)] is op Bio Rad se AG MP-50 makroporeuse kationiese uitruilerhars in verskillende sitroensuur – salpetersuur mengsels met sukses bepaal. Die verdelingskoëffisiënte is in 0.1 M en 0.25 M sitroensuur met verskillende konsentrasies van salpetersuur (0.2 M, 0.5 M en 1.0 M) bepaal. Twee-komponent [Mo(VI)-Y(III); Zr(IV)-La(III) en As(V)-Zn(II)] en drie-komponent [Nb(V)-Ta(V)-V(V)] skeidings op ’n 10 ml AG MP-50 harskolom is suksesvol bepaal om te demonstreer hoe die verdelingskoëffisiëntresultate gebruik kan word. As ’n uitvloeisel van die verdelingskoëffisiëntresultate vir Mg(II) en Na(I), is ’n voorstel ingedien om die huidige natrium-22 produksiemetode, tans in gebruik by iThemba LABS, te modifiseer. Die resultate het nie ’n skeiding tussen die twee elemente voorspel nie, maar het bewys dat ’n teorie oor die gebruik van sitroensuur in die produksie nie heeltemal korrek was onder die huidige toestande nie.

Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Capillary electrophoresis (CE) has recently attracted considerable attention as a promising analytical technique for the separation of cations and anions in complex matrices. Determination of ions in aqueous samples using capillary electrophoresis can be accomplished with indirect UV detection. Most inorganic ions have weak absorption profiles in the UV-Vis wavelength range. These mostly non-absorbing species are commonly detected by indirect UV absorbance through addition of an absorbing co-ion (chromophore) into the electrolyte. Inorganic cations most often require an additional complexing agent to selectively alter their similar mobilities and proper separation. For optimal determination of alkali, alkaline, and transition metal ions, several electrolytes systems were studied. These include pyridine, imidazole and 4- aminopyridine as UV-absorbing species and glycolic acid, a-hydroxyisobutyric acid and their mixture were used as complexing reagents. A mixture of 10 metal ions (K+, Na+,Ca2+, Mg2+, Mn2+, Fe2+, Cd2+, Pb2+, Ni2+and Zn2+) was successfully separated. Detectionwas performed at 210,214 and 254 nm. In the anion determination chromate and 2, 6 pyridine dicarboxylic acids (PDC) were used as back ground electrolytes for inorganic ions (F-, CI- en SO₄² ̄ ) and organic acids (tartaric acid, malic acid, succinic acid and citric acid) separations respectively. Electroosmotic flow (EOF) was reversed in the direction of the anode by adding Cetyltrimethylammonium bromide (CTAB) to the electrolyte. Highly alkaline conditions were used to confer a negative charge on inorganic and organic anions to promote their migration towards the anode. The detection wavelength was 200 nm. All peaks were completely resolved and well separated. The limit of detection (LOD) of cations and anions were in the range of 0.5 - 3 ppm and 2 - 3.5 ppm respectively. The described methods were used successfully in routine analysis of real samples. This includes the qualitative and quantitative analysis of an environmental water samples from the areas surrounding Stellenbosch, beverages and orange juice. / AFRIKAANSE OPSOMMING: Kapillêre Elektroforese (CE) het in die onlangse verlede heelwat aandag getrek as "n belowende analitiese tegniek vir die skeiding van katione en anione in komplekse monsters. Die bepaling van ione in waterige medium met kapillêre elektroforese word gedoen deur indirekte Ultraviolet (UV) deteksie aangesien meeste anorganiese ione swak absorbsie in die die sigbare UV (UV-Vis) golflengtegebied toon. Deteksie van hierdie meestal nie-absorberende spesies word algemeen gedoen deur indirekte UV absorbansie deur die byvoeging van "n ko-ioon (chromofoor) tot die elektroliet. Anorganiese katione benodig dikwels "n addisionele komplekserings reagens om selektief hulle eenderse mobiliteite te verander en sodoende goeie skeiding te bewerkstellig. Vir die optimale bepaling van alkali-, alkali-aard- en oorgansmetaal ione is verskeie elektrolietsisteme bestudeer. Hierdie sluit in piridien, imidasool en 4-aminopiridien as UV absorberende spesies en glikoliensuur, a-hydroksie-isobottersuur asook "n mengsel van die twee as komplekserings reagense. "n Mengsel van 10 metaalione (K+, Na+, Ca2+, Mg2+, Mn2+, Fe2+, Cd2+, Pb2+, Ni2+ en Zn2+) is sukselvol op hierdie wyse geskei. Deteksie is gedoen by golflengtes van 210, 214 en 254 nm. Vir die anioon bepaling is chromaat en 2,6-piridiendikarboksielsuur gebruik as agtergrond elektroliete vir die skeiding van anorganiese anione (F-, CI- en SO₄² ̄ ) en organiese sure (tartaarsuur, malonsuur, suksiensuur en sitroensuur), onderskeidelik. Elektroosmotiese vloei (EOF) is omgekeer na die rigting van die anode deur byvoeging van setieltrimetielammoniumbromied (CTAB) by die elektroliet. Sterk alkaliese kondisies is gebruik om 'n negatiewe lading op die anorganiese en organiese anione te konsentreer en sodoende hul migrasie na die anode te bevorder. Die deteksiegolftengte hier gebruik was 200 nm. Volkome resolusie en goeie skeiding is gerealiseer vir al die pieke. Die deteksielimiete (LOD) vir die katione en die anione was 0.5 - 3 ppm en 2 - 3.5 ppm, onderskeidelik. Die metodes wat beskryf word is suksesvol aangewend vir roetiene analise van werklike monsters. Dit sluit in kwalitatiewe sowel as kwantitatiewe analise van omgewingswater monsters uit die Stellenbosch area, koeldranke en lemoensap.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

Layered double hydroxides (LDH) have been principally known as anion-exchanging, clay-like materials for several decades, and continues to be the main driving force for current and future research. The chemical interactions of LDH, with transition metallocyanides, have been a popular topic of investigation for many years, partly due to the use of powder x-ray diffraction and infrared spectroscopy as the main characterization tools. Each transition metallocyanide has a characteristic infrared stretching frequency that can be easily observed, and their respective sizes can be observed while intercalated within the interlayer of the LDH. The ability of LDH to incorporate metal cations or any ions/molecules/complexes, that have a postive charge, have not been previously investigated, mainly due to the chemical and physical nature of LDH. The possibility of cationic incorporation with LDH would most likely occur by surface adsorption, lattice metal replacement, or by intercalation into the LDH interlayers. Although infrared spectroscopy finds it main use through the identification of the anions incorporated with LDH, it can also be used to study and identify the various active and inactive bending and stretching modes that the metal hydroxide layers have.

Aldol cyclotrimerizations have been used to achieve the rational chemical synthesis of both fullerenes and fullerene fragments in the past. Under certain conditions this reaction produces the corresponding cyclotetramer which has sometimes been regarded as an undesired byproduct. This work details efforts to synthesize and use these cyclotetramers toward a synthesis of a C240 fullerene fragment. One principal focus in this work is tridecacyclene, a cyclic tetramer of acenaphthylene given its name by our group for its thirteen rings. Relatively low yields for the synthesis of tridecacyclene and its derivatives drove us to investigate the mechanism of its formation and attempt to optimize its production. During this process, novel dione products were isolated from the attempted cyclotetramerization of two dimeric species. Characterization of these products by X-ray crystallography gave valuable insight into the reaction pathway, leading us to a new proposed mechanism of formation for the cyclotetramerization products observed in these aldol reactions. β-hydroxy-α-diazoketones are suitable progenitors to vinyl cation intermediates whose use in chemical synthesis is relatively unexplored. As part of an extensive project to develop the chemistry of vinyl cations for use in carbon-carbon bond forming reactions to build important molecular scaffolds, a range of β-hydroxy-α-diazoketones containing a pendent nucleophilic alkene were synthesized. Treatment of these compounds with Lewis acids gave either lactone or cyclopentenone products depending on the substrate used. Proposed herein is a mechanism involving a key acylium intermediate which, depending on the position of the pendent alkene, results in different product outcomes. In a collaborative effort to further investigate the known anti-cancer properties of fusarochromanone, a fungal metabolite that is isolated from Fusarium-infected feed from cold climates, a large-scale synthesis of this natural product was explored. An efficient, scalable synthesis of the previously prohibitively expensive amidochromanone starting material has been achieved and its elaboration to fusarochromanone has been demonstrated.

Membrane processes are increasingly used in water treatment. Experiments were performed using stirred cell equipment, polymeric membranes and synthetic surface water containing natural organics, inorganic colloids and their aggregates, and cations. All processes could remove a significant amount of natural organics. Pretreatment with ferric chloride was required to achieve significant organic removal with MF and high MWCO UF. Additionally, fouling mechanisms for the three processes were investigated. Crucial parameters were aggregate characteristics (fractal structure, stability, organic-colloid interactions), solubility of organics and calcium, and hydrodynamics. In MF, fouling by pore plugging was most severe. Variations in solution chemistry changed the aggregation state of the colloids and/or natural organic matter and dramatically affected rejection and fouling behaviour. UF membrane fouling was mainly influenced by pore adsorption and could improve natural organics rejection significantly. Coagulant addition shifted fouling mechanism from pore adsorption to cake formation. Aggregate structure was most significant for flux decline. In NF, rejection of natural organics involved both size and charge exclusion. Fouling was caused by precipitation of a calcium-organic complex. Fouling could be avoided by pretreatment with metal salt coagulants. Thorough chemical characterisation of the organics used demonstrated that only size and aromaticity can be related to fouling. The study is concluded with a process comparison based on a water quality parameter and a cost comparison. Treatment cost of microfiltration with chemical pretreatment was similar to that of nanofiltration at a comparable natural organics rejection.

Aim of thesis: Immuno-stimulating complexes (ISCOMs) are particulate vaccine delivery systems composed of Quillaja saponins, cholesterol and phospholipid. ISCOMs are typically spherical cage-like structures with a diameter of 40 nm and carry a negative charge. Incorporation of the respective vaccine antigen into the particles generates more potent vaccines than a simple mixture of both vaccine components. This requires the antigen to display either hydrophobic domains or positive charges, which allow interaction with the ISCOM particles. However, not all antigens fulfil this requirement and modification of these becomes necessary. Hence, the aim of this study was to design novel preparations of ISCOMs with a positive charge, suitable for adsorption of native hydrophilic antigens and poly-nucleotides, and test their potential as a novel vaccine carrier platform. Methods: Two cationic lipids, DC-cholesterol and DOTAP, were selected to prepare the cationic modifications of ISCOMs. DC-cholesterol substituted for cholesterol in classical ISCOMs, whereas DOTAP substituted for their phospholipid component. The phase behaviour of colloidal systems containing Quil-A, phosphatidylcholine (PC) and DC-cholesterol and of colloidal systems comprised of Quil-A, cholesterol and DOTAP was studied by transmission electron microscopy (TEM). Lipid-film hydration was utilised as the first method to prepare these colloidal systems. Selected compositions containing either DC-cholesterol or DOTAP were also prepared by dialysis as second method. A novel third method for preparing homogenous dispersions of classical ISCOMs was developed utilising ethanol injection. This method was also applied in an attempt to prepare cationic modifications of ISCOMs including DC-cholesterol and DOTAP. As in the colloidal systems comprising Quil-A, PC and DC-cholesterol transformations of structures were observed upon dilution with aqueous solutions, these transitions were also studied on classical ISCOMs using TEM and dynamic light scattering techniques. Loading of cationic colloidal structures composed of Quil-A, PC and DC-cholesterol was performed with the model protein antigen ovalbumin (OVA) and a model plasmid, and the resulting structures were analysed by fluorescence spectroscopy, TEM and gel electrophoresis. The immunological properties of non-loaded and OVA-loaded structures were studied in terms of their ability to activate murine bone marrow derived dendritic cells (mBMDC) as antigen presenting cells (APC) and OVA-specific CD8+ T cells in vitro. Results: Substitution of cholesterol in classical ISCOMs with DC-cholesterol resulted in the formation of cationic cage-like structures similar to the classical particles. These were observed in pseudo-ternary Quil-A:PC:DC-cholesterol systems and even in pseudo-binary Quil-A:DC-cholesterol systems prepared by lipid-film hydration. Compositions at which cage-like structures were observed included high weight proportions of DC-cholesterol (> 60%). However, samples were relatively heterogeneous, and aggregation of colloidal structures was observed at equimolar ratios of Quil-A and DC-cholesterol. The ionic strength, pH and composition of the hydration buffer were demonstrated to be important variables influencing the formation of cage-like structures. Morphological changes of pre-formed cationic cage-like structures were observed upon dilution. However, classical anionic ISCOMs showed a similar behaviour. The numbers of cationic cage-like structures appeared to increase upon prolonged storage of samples. Purification of structures and longitudinal analysis of their composition suggested an increased formation of stoichiometrically defined DC-cholesterol:Quil-A:PC complexes over time, rather than a change in composition. The substitution of phospholipid in classical ISCOMs with DOTAP also resulted in heterogeneous dispersions, and aggregation of colloidal structures was observed at equimolar ratios of Quil-A and DOTAP. Phase separation phenomena were proposed based on TEM observations. However, the formation of cage-like particles with a positive [zeta]-potential was not observed. Although ethanol injection was introduced as a novel method to prepare classical ISCOMs, its application did not result in more homogenous dispersions of cationic colloidal structures containing DC-cholesterol or DOTAP. Dialysis also failed to produce higher numbers of well-defined cationic particles, although using this method homogeneous, anionic ISCOM-like particles containing DOTAP were obtained. The efficient adsorption of OVA and plasmid DNA onto cationic structures containing Quil-A, PC and DC-cholesterol was demonstrated. The adsorption process was accompanied with a decrease in [zeta]-potential, aggregation of structures and changes in the ultra-structure, particularly at high protein:lipid ratios. The in vitro immunogenicity of dispersions containing Quil-A, PC and DC-cholesterol was equivalent to that of classical ISCOMs in terms of activation of mBMDC and OVA-specific CD8+ T cells, even though smaller amounts of Quillaja saponins and total lipid were co-delivered with OVA. Furthermore, the uptake of OVA by BMDC appeared to be more efficient in conjunction with the novel cationic dispersions. Conclusions: Cationic colloidal structures containing Quillaja saponins offer great potential as vaccine delivery systems. Their advantages thus far include simple and efficient adsorption of antigen, efficient uptake by APC and immunological activity in vitro. With further development, cationic carriers containing Quillaja saponins may constitute a very potent vaccine delivery platform suitable for a variety of subunit antigens, and suffice both pharmaceutical and immunological requirements.

Includes bibliographies. / xi, 240 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The complexation of a range of monovalent and divalent metal ions by the aliphatic bridge cryptands C22C2 and C22C8; and the complexation of alkali metal ions by the pendant arm tetraaza macrocycle 1,4,7,10-tetrakis(2-methoxyethyl)1,4,7,10-tetraazacyclododecane, and the factors effecting complex stability and lability, have been investigated. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemistry, 1995