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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Amino acid analysis : hydrolysis, color reagent, and sensitivity

Jones, Max Albert January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
12

Coordination studies of inositols with aluminium and related cations

Chokazinga, Davlin January 2003 (has links)
In this work cis-inositol, epi-inositol and myo-inositol carbonate were successfully synthesised and used for coordination studies. The preparation of cis-inositol was achieved by reduction of tetrahydroxybenzoquinone via hydrogenation with palladium hydroxide as the catalyst and was purified by chromatographic separation using Dowex resin. The synthesis of epi-inositol was achieved by the nitric acid oxidation of myo-inositol to form epi-inosose which was subsequently reduced by hydrogenation using palladium hydroxide as the catalyst. myo-Inositol was converted into its mono-orthoformate derivative and the equatorial hydroxy group was then protected as a tertiary-butyldimethylsilyl ether. The carbonate group was introduced onto this protected inositol and then the protecting groups were removed by acid hydrolysis. The coordination characteristics of four inositols, viz cis-inositol, epi-inositol, myo-inositol and myo-inositol carbonate with calcium, aluminium, gallium, lanthanum and samarium ions have been investigated. Interactions of the aluminate anion with epi-inositol and myo-inositol in deuterated sodium hydroxide were also investigated. Three methods were used in the study of complexation behaviour of these systems. namely, [superscript]13C NMR spectroscopy, HPLC and ion exchange chromatography. [superscript]13C NMR spectroscopy was found to be most useful for determining possible complexation behaviour of the inositols. Chemical shift changes of the resonance signals in the [superscript]13C NMR spectra on sequential addition of cations to solutions of the inositols at near neutral pH, have led to determination of possible coordination sites of the inositols. In general, large induced chemical shift changes have been interpreted to signify strong cation-inositol interaction at specific hydroxy groups. / Triaxial sites of the inositols have shown a preference to coordinate small ions with ionic size of at least 60 pin, smaller ions than this displayed very weak interactions. Likewise large ions (90-100 pm) imparted weak interactions on triaxial sites of the inositols. These large ions coordinated well with the axial-equatorial-axial sites of the inositols although it was observed that calcium ions appeared to form a 2:1 ligand:cation complex with cis-inositol at the triaxial site despite being a large cation (100 pm). The detection of complex formation by HPLC showed a possible formation of very stable complexes of epi-inositol complexes with calcium ions. However, a change of refractive index of the solution on sequential addition of the cation may have caused an interference in the results such that direct interpretation was not possible. Ion exchange chromatography provided the quickest guide on how strongly the inositols interact with a particular cation. However, determination of complex stoichiometry and or structure was not possible using this technique.
13

Indirect photometric chromatography of iodide ion in aqueous solutions /

Allyn, M. Liz. January 1987 (has links)
Thesis (M.S.)--Rochester Institute of Technology, 1987. / Typescript. Includes bibliographical references (leaves 59-60).
14

Aplicacao da cromatografia de ions no controle de materiais de interesse nuclear

PIRES, MARIA A.F. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:32:50Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:43Z (GMT). No. of bitstreams: 1 03535.pdf: 3650830 bytes, checksum: bbc8f2898c5bbb98e5ef60f35f76a159 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Química - Universidade de São Paulo - IQ/USP
15

Aplicacao da cromatografia de ions no controle de materiais de interesse nuclear

PIRES, MARIA A.F. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:32:50Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:43Z (GMT). No. of bitstreams: 1 03535.pdf: 3650830 bytes, checksum: bbc8f2898c5bbb98e5ef60f35f76a159 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Química - Universidade de São Paulo - IQ/USP
16

Ostrich calpastatin purification and partial characterization of the liver inhibitor

Roman, Henry James January 2000 (has links)
The isolation and purification of calpastatin from ostrich liver is presented, along with its physicochemical and kinetic properties. By using extraction from liver, ion-exchange chromatography on DEAE-Toyopearl, heating to 90 °C for 10 min and rechromatography on Toyopearl Super-Q 650 S, ostrich calpastatin was isolated and purified from ostrich liver. The purified intact calpastatin showed homogeneity on SDS-PAGE (Mr of 105.6 K). Amino acid analysis showed that ostrich calpastatin resembled that of rabbit liver and human erythrocyte calpastatin. An N-terminal sequence could not be obtained because the N-terminus was found to be blocked by an as yet unknown amino acid residue. The Mr values of degradative forms of ostrich liver calpastatin were determined to be 56 K and 90 K. By using PAG-IEF the pI of the intact form was determined to be 5.1. Ostrich liver calpastatin behaved characteristically like other calpastatins during kinetic analysis. Calpastatin inhibited calpain from pH 6 to 9 and was found to be unaffected by temperatures as high as 100 °C. Calpastatin also inhibited calpain activity at Ca2+ concentrations ranging from 1 to 10 mM. The inhibitor was shown to be phosphorylated because after incubation with alkaline phosphatase there was a decrease in inhibitory activity. No inhibitory effects were detected against other proteases such as chymotrypsin and trypsin, with both proteases inactivating calpastatin completely. Ostrich liver calpain was shown to have a pH optimum of 7.5 and a temperature optimum of 30 °C. In terms of its thermodynamic properties it resembled that of other ostrich proteases; DH, DS and DG being 47.07 kJ/mol, -91.1 J/mol/K and 74.237 kJ/mol, respectively. Ostrich liver calpain showed a Km of 0.14 % (w/v). The enzyme was active at both milli- and micro-molar concentrations of Ca2+. Ostrich liver calpastatin showed many physical, chemical and kinetic properties similar to those of other known calpastatins.
17

Chemical characterisation of atmospheric aerosols in Soweto, Bethlehem and Thohoyandou using energy dispersive x-ray fluorescence spectroscopy and ion chromatography

Lumka, Mandisile 05 March 2012 (has links)
M.Sc. / Aerosol samples were collected at stations using simple filter unit, loaded with a 4 7 mm diameter pore size Nuclepore membrane filter. The sampling duration was 24 hours for each sample, with the total of 11 samples: seven for Thohoyandou and four for Bethlehem. The samples were analyzed with energy dispersive X-ray fluorescence spectrometry for up to 20 elements. Comparison for elemental concentrations of the data showed that the samples fall into three clusters on average (major: Ca, Cl, Si. S, Fe and AI; intermediate: K, Ti, Pb, Brand Zn; minor: Mn, Cr, As, Sr, Ni and Cu), with the samples collected from Bethlehem having high concentrations in all clusters. High concentrations in the samples collected on Bethlehem were attributed to entrainement of dust particles during the dry winter period. The results also show that the elements are associated with anthropogenic emissions. Therefore, the sampling station at Thohoyandou is considered as a background station due to the low aerosol concentration. The aerosol concentration levels at Thohoyandou can be attributed to biogenic sources because of the large presence of large forest areas in the region and in the vicinity of the sampling location. The samples collected in both regions reveal highly enriched sulphur, chlorine, zinc and lead. It is clearly proved that these elements come from local soil. Chromium and copper were both slightly enriched in Thohoyandou, but the concentration data for these two elements are not available. However it is supposed that these elements come from local soil as well. In another aerosol analysis, passive (diffusive) samplers were used to measure concentration levels for sulphur dioxide and nitrogen dioxide. The measurement campaign was carried out from Soweto in Johannesburg and Bohlokong in Bethlehem with the campaign lasting for two months during the w~nter season. A very clear result derived for sulphur dioxide was the dominating source contribution from use of coal for heating and cooking in both areas. For nitrogen dioxide, it was found that contribution from traffic in highly populated areas and from industrial activities in the neighbourhood of the two areas was the source. The role played by wood burning, is also another additional source used for domestic heating and even cooking.
18

Studies in ion exchange chromatography

Polite, Lee Nicholas January 1988 (has links)
This dissertation investigates three major problems in IC, ranging from the practical to the theoretical. The first is of interest to the field of quantitative analysis. Since ion chromatography is primarily a quantitative technique, the linear range of the detector is of particular interest. The linear range was determined to be nearly five orders of magnitude for several common ions. The probes used were fluoride, chloride, sulfate, sodium, and potassium with concentrations ranging from 10 ppb to 1000 ppm. This portion of the dissertation describes the first attempt made to elucidate the linear detection range in ion chromatography using micro-membrane suppression. The Iinearity experiments demonstrate the versatility of ion chromatography with respect to quantifiable concentrations. However, a major problem is encountered when attempting to determine a trace ion concentration in the presence of a high concentration of a similarly charged ion (matrix ion). The second part of this dissertation offers a solution to this problem. In ion chromatography, the large excess of a matrix ion affects not only the ions expected in that region of the chromatogram, but also destroys the chromatographic exchange process. One objective of this study was to develop a rapid quantitative method to determine 5 ppm chloride in the presence of 100,000 ppm sulfate. A standard anion exchange column will completely lose resolution between chloride and sulfate at a sulfate concentration of approximately 2500 ppm. The apparatus designed and built by the author uses two analytical ion—exchange columns coupled in series by a high pressure switching valve. ln order to complete the system, the author designed and built y a high pressure conductivity detector cell to monitor the conductivity of the effluent from the first column. The system works by overloading the first column and then allowing the effluent to pass onto the second column. When the trace chloride in on the second column, the first column is switched out of line. This process allows the trace chloride to be separated from the residual sulfate. The column switching study brought to light several theoretical questions about the inner workings of the packing materials used in ion chromatography. These questions include the effects that flow rate and temperature have on capacity and efficiency in ion chromatography separations. Using chloride and sulfate as probes, the chromatographic efficiency was shown to decrease from 30° to 60° C. Even more surprising was the result that sulfate retention increased with increasing temperature while chloride retention decreased under the same conditions. Detailed studies as well as possible explanations are included in the third part of this dissertation. / Ph. D.
19

Detector Comparison for Simultaneous Determination of Organic Acids and Inorganic Anions

Pannell, Daniel K. (Daniel Kirk) 08 1900 (has links)
The research reported here is a study of detector systems to determine those most suited for simultaneous organic acid, inorganic anion determination. Comparisons are made on the basis of detection limits and sensitivities for conductivity, UV/Vis, photoconductivity, and derivative conductivity detection systems. The investigation was made using a constant chromatographic system with the only variable component being the detector system. Eluant optimization conditions for each detector are reported along with tables reporting detection limits and sensitivities for each detector system. Various chromatograms are also shown to provide a visual comparison between detector results.
20

Ion Chromatography of Soluble Cr(III) and Cr(VI)

Huang, Julie Shiong-Jiun 08 1900 (has links)
Ion chromatography coupled with a conductivity detector was used to investigate the analysis of Cr(III) and Cr(VI) in aqueous samples. An IC methodology for Cr(III) was developed using a cation column and an eluent containing tartaric acid, ethylenediamine, and acetonitrile at pH 2.9. The detection limit of this method can reach 0.1 ppm level with good precision. Several operational parameters were evaluated during the regular use of the method. Comparison of the IC method with AA method showed good agreement between the two methods. The anion exchange column was used for Cr(VI) determination. The best results were obtained with an eluent containing sodium gluconate, borate buffer, glycerin, and acetonitrile. The retention time for the Cr207 2 - sample was 11 min. and the calibration curve was linear between 1.0 and 100 ppm.

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