'n Kritiese evaluering van ioonchromatografiese metodes vir die bepaling van Cr(III) en Cr(VI) in industriële afloop
- Authors: De Beer, Hannelie
- Date: 2015-02-12
- Subjects: Ion exchange chromatography
- Type: Thesis
- Identifier: uj:13299 , http://hdl.handle.net/10210/13317
- Description: M.Sc. (Chemistry) , Please refer to full text to view abstract
- Full Text:
- Authors: De Beer, Hannelie
- Date: 2015-02-12
- Subjects: Ion exchange chromatography
- Type: Thesis
- Identifier: uj:13299 , http://hdl.handle.net/10210/13317
- Description: M.Sc. (Chemistry) , Please refer to full text to view abstract
- Full Text:
Chromium speciation analysis by ion chromatography coupled with ICP-OES
- Authors: Jansen van Vuuren, Samantha
- Date: 2012-09-04
- Subjects: Speciation (Chemistry) , Chromium , Ion exchange chromatography , Chromatographic analysis , Inductively coupled plasma spectrometry
- Type: Thesis
- Identifier: uj:3510 , http://hdl.handle.net/10210/6899
- Description: M.Sc. , The behaviour i.e. the distribution, bioavailability and toxicity of an element depends on the particular species in which it is present. That being said the prediction of the behaviour of species can therefore not be predicted by determination of the total concentration alone. Speciation analysis is thus an important process, which seeks to identify and quantify the species that occur in a sample. By identifying the species one is better equipped to predict the behaviour of the element if it were released into the ecosystem as well as if it were used in industrial processes. The speciation analysis of the dominant chromium species, Cr(III) and Cr(VI), has received much attention as these contradictory species are involved in many industrial processes such as plating and tanning for example. The species have opposing behaviour as Cr(III) is found to be a necessary micronutrient for mammals where as Cr(VI) is known to be toxic. Of the numerous methods developed for chromium speciation analysis, the on-line process of chromatographic preconcentration followed by simultaneous detection with a sensitive detector produces a synergistic effect for the successful speciation analysis of chromium. It was thus decided to study ion chromatography hyphenated with an ICP-OES as a means of studying chromium species. Anion chromatography coupled with ICP-OES was the basis for the development of the first method. Complexation of Cr(III) with EDTA to form a monovalent anion preceded its separation from Cr(VI) as the chromate anion. A carbonate-bicarbonate eluent was used to elute the species from a Dionex AG 9 guard column coupled with an AS 9 separation column. This method proved to be effective and fast, with each analysis taking less than two minutes. The second method was based on cation chromatography in the form of a Dionex CG12A guard column being coupled with an ICP-OES spectrometer as the detector. This method made use of a gradient elution program in which hexavalent chromium was eluted first with ammonium nitrate followed by trivalent chromium with nitric acid. This method was successfully applied to synthetic samples and was found to be effective.
- Full Text:
- Authors: Jansen van Vuuren, Samantha
- Date: 2012-09-04
- Subjects: Speciation (Chemistry) , Chromium , Ion exchange chromatography , Chromatographic analysis , Inductively coupled plasma spectrometry
- Type: Thesis
- Identifier: uj:3510 , http://hdl.handle.net/10210/6899
- Description: M.Sc. , The behaviour i.e. the distribution, bioavailability and toxicity of an element depends on the particular species in which it is present. That being said the prediction of the behaviour of species can therefore not be predicted by determination of the total concentration alone. Speciation analysis is thus an important process, which seeks to identify and quantify the species that occur in a sample. By identifying the species one is better equipped to predict the behaviour of the element if it were released into the ecosystem as well as if it were used in industrial processes. The speciation analysis of the dominant chromium species, Cr(III) and Cr(VI), has received much attention as these contradictory species are involved in many industrial processes such as plating and tanning for example. The species have opposing behaviour as Cr(III) is found to be a necessary micronutrient for mammals where as Cr(VI) is known to be toxic. Of the numerous methods developed for chromium speciation analysis, the on-line process of chromatographic preconcentration followed by simultaneous detection with a sensitive detector produces a synergistic effect for the successful speciation analysis of chromium. It was thus decided to study ion chromatography hyphenated with an ICP-OES as a means of studying chromium species. Anion chromatography coupled with ICP-OES was the basis for the development of the first method. Complexation of Cr(III) with EDTA to form a monovalent anion preceded its separation from Cr(VI) as the chromate anion. A carbonate-bicarbonate eluent was used to elute the species from a Dionex AG 9 guard column coupled with an AS 9 separation column. This method proved to be effective and fast, with each analysis taking less than two minutes. The second method was based on cation chromatography in the form of a Dionex CG12A guard column being coupled with an ICP-OES spectrometer as the detector. This method made use of a gradient elution program in which hexavalent chromium was eluted first with ammonium nitrate followed by trivalent chromium with nitric acid. This method was successfully applied to synthetic samples and was found to be effective.
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Chemical characterisation of atmospheric aerosols in Soweto, Bethlehem and Thohoyandou using energy dispersive x-ray fluorescence spectroscopy and ion chromatography
- Authors: Lumka, Mandisile
- Date: 2012-03-05
- Subjects: Aerosols , X-ray spectroscopy , Ion exchange chromatography
- Type: Thesis
- Identifier: uj:2123 , http://hdl.handle.net/10210/4491
- Description: 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.
- Full Text:
- Authors: Lumka, Mandisile
- Date: 2012-03-05
- Subjects: Aerosols , X-ray spectroscopy , Ion exchange chromatography
- Type: Thesis
- Identifier: uj:2123 , http://hdl.handle.net/10210/4491
- Description: 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.
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Radiochemiese en ioonchromatografiese metodes vir die bepaling van silwerhaliedkomplekse en haliedione in sout- en oliematrikse
- Authors: Taljaard, Immanda
- Date: 2014-03-12
- Subjects: Radiochemistry , Ion exchange chromatography , Chromatographic analysis , Silver halides , Halides
- Type: Thesis
- Identifier: uj:4311 , http://hdl.handle.net/10210/9663
- Description: M.Sc. (Chemistry) , The storage as solid Ag12BI(s) of reactor produced 12BI (t~ = 1.6 x 107 a) in underground respositories can present an environmental problem due to the potential release of radioactive 12BI into the environment over extended storage periods. One process that causes concern is the solubilization of AgI through complexation when brought into contact with underground water, particularly those with high salt content. In this work the charaqterization of the complexation equilibria in the AgI(s)/I-(aq),CI-(aq) system was studied. Solu- I tions containing high CI- and low 1- concentrations were of special interest with regard to the possible formation of ternary complexes. The presence of AgICI22- was indicated experimentally but no evidence of other ternary species like AgI2CI2- or AgIsCIS- could be established. Solubilities were determined radiochemically by using specially prepared 110mAgI. Solubility curves for AgI in different I-/CI- mixtures were adequately explained in terms of models consisting of the species AgCls2-, AgC14S-, AgIs2-, AgI4s- and AgICI22-. Distribution curves were calculated for different I-/CI- mixtures. As an alternative detection mode for silver-determination a flow injection system incorporating a micro-column of activated alumina was used in conjuntion with flame atomic absorption spectrometry for the pre-concentration and determination of silver in water. The procedure was successfully applied to a range of water samples, but no determination of silver in halide or perchlorate media was possible. The limit of detection based on a sample volume of 15 cms was 4.5 ~gdm-3 and the relative standard deviations at 50 and 5 ~gdm-3 were 5.4 and 19%, respectively. In part B of this work a method for the determination of chloride in organic compounds (oils provided by the Atomic Energy Corporation) by using an Parr oxygen bomb and ion chromatography was studied. The combustion products were absorbed in H20. The solution was injected into an ion chromatograph equipped with an anion analytical column, membrane suppressor and conductivity detector. The instrument response was calibrated using different standard solutions. These were prepared from several organic solutions, an organic salt and from sodiumchloride. Calibration curves were linear over a wide range and presented good reproducibility. It differed however according to the type of standard solution used. The limit of detection was 255 ~gdm-3 and the relative standard deviations at 10, 1 and 0.5 ugcm-3 were 0.52, 1.64 and 3.5%, respectively. As an alternative decomposition method wet decomposition within a sealed system (autoclave) was used. Due to the high blank values in this method no analysis of substances could be made in the lower ugcm-3 range.
- Full Text:
- Authors: Taljaard, Immanda
- Date: 2014-03-12
- Subjects: Radiochemistry , Ion exchange chromatography , Chromatographic analysis , Silver halides , Halides
- Type: Thesis
- Identifier: uj:4311 , http://hdl.handle.net/10210/9663
- Description: M.Sc. (Chemistry) , The storage as solid Ag12BI(s) of reactor produced 12BI (t~ = 1.6 x 107 a) in underground respositories can present an environmental problem due to the potential release of radioactive 12BI into the environment over extended storage periods. One process that causes concern is the solubilization of AgI through complexation when brought into contact with underground water, particularly those with high salt content. In this work the charaqterization of the complexation equilibria in the AgI(s)/I-(aq),CI-(aq) system was studied. Solu- I tions containing high CI- and low 1- concentrations were of special interest with regard to the possible formation of ternary complexes. The presence of AgICI22- was indicated experimentally but no evidence of other ternary species like AgI2CI2- or AgIsCIS- could be established. Solubilities were determined radiochemically by using specially prepared 110mAgI. Solubility curves for AgI in different I-/CI- mixtures were adequately explained in terms of models consisting of the species AgCls2-, AgC14S-, AgIs2-, AgI4s- and AgICI22-. Distribution curves were calculated for different I-/CI- mixtures. As an alternative detection mode for silver-determination a flow injection system incorporating a micro-column of activated alumina was used in conjuntion with flame atomic absorption spectrometry for the pre-concentration and determination of silver in water. The procedure was successfully applied to a range of water samples, but no determination of silver in halide or perchlorate media was possible. The limit of detection based on a sample volume of 15 cms was 4.5 ~gdm-3 and the relative standard deviations at 50 and 5 ~gdm-3 were 5.4 and 19%, respectively. In part B of this work a method for the determination of chloride in organic compounds (oils provided by the Atomic Energy Corporation) by using an Parr oxygen bomb and ion chromatography was studied. The combustion products were absorbed in H20. The solution was injected into an ion chromatograph equipped with an anion analytical column, membrane suppressor and conductivity detector. The instrument response was calibrated using different standard solutions. These were prepared from several organic solutions, an organic salt and from sodiumchloride. Calibration curves were linear over a wide range and presented good reproducibility. It differed however according to the type of standard solution used. The limit of detection was 255 ~gdm-3 and the relative standard deviations at 10, 1 and 0.5 ugcm-3 were 0.52, 1.64 and 3.5%, respectively. As an alternative decomposition method wet decomposition within a sealed system (autoclave) was used. Due to the high blank values in this method no analysis of substances could be made in the lower ugcm-3 range.
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Chemie in die bereiding, skeiding en gehaltebeheer van draervrye radioisotope en radiofarmaseutiese middels
- Van der Walt, Tjaart Nicolaas
- Authors: Van der Walt, Tjaart Nicolaas
- Date: 2014-06-02
- Subjects: Ion exchange chromatography , Radioisotopes , Radiopharmaceuticals
- Type: Thesis
- Identifier: uj:11330 , http://hdl.handle.net/10210/10922
- Description: M.Sc. (Chemistry) , This thesis describes the preparation of lead-203 and thallium-201 via proton induced nuclear reactions on natural lead cyclotron targets. The separation of bismuth-206, lead-203 and thallium-201 from the lead target material was investigated in this study. Excellent separations, by ion exchange chromatography, were developed to prepare carrier-free bismuth-206, lead-203and thallium-201. The separation of lead-203 and thallium-201 from thallium cyclotron target material was also investigated in this study, and excellent separations, using ion exchange chromatography, were achieved. The development of spectrophotometric methods for the determination of copper and europium in radiopharmaceuticals was investigated and sensitive methods were compiled. The determination of BIDA, DISIDA, DTPA and HOP in 99-Tc· labelled compounds was also studied in this thesis, and indirect spectrophotometric methods were developed. The determination of BIDA and DISIDA in labelling kits was studied and a complexometric titration, with copper as titrant and eriochrome cyanine R as indicator, was developed. The preparation of calciumtrisodium diethyltriaminepentaacetic acid, for use in DTPA labelling kits, and the development of quality control tests on the product were included in this study. A complexometric method was compiled to determine the calcium and DTPA contents of the CaNa3DTPA. Successive titrations of DTPA (with thorium) and calcium (with DCTA) are carried out using the same sample solution; methyl thymol blue is used as indicator.
- Full Text:
- Authors: Van der Walt, Tjaart Nicolaas
- Date: 2014-06-02
- Subjects: Ion exchange chromatography , Radioisotopes , Radiopharmaceuticals
- Type: Thesis
- Identifier: uj:11330 , http://hdl.handle.net/10210/10922
- Description: M.Sc. (Chemistry) , This thesis describes the preparation of lead-203 and thallium-201 via proton induced nuclear reactions on natural lead cyclotron targets. The separation of bismuth-206, lead-203 and thallium-201 from the lead target material was investigated in this study. Excellent separations, by ion exchange chromatography, were developed to prepare carrier-free bismuth-206, lead-203and thallium-201. The separation of lead-203 and thallium-201 from thallium cyclotron target material was also investigated in this study, and excellent separations, using ion exchange chromatography, were achieved. The development of spectrophotometric methods for the determination of copper and europium in radiopharmaceuticals was investigated and sensitive methods were compiled. The determination of BIDA, DISIDA, DTPA and HOP in 99-Tc· labelled compounds was also studied in this thesis, and indirect spectrophotometric methods were developed. The determination of BIDA and DISIDA in labelling kits was studied and a complexometric titration, with copper as titrant and eriochrome cyanine R as indicator, was developed. The preparation of calciumtrisodium diethyltriaminepentaacetic acid, for use in DTPA labelling kits, and the development of quality control tests on the product were included in this study. A complexometric method was compiled to determine the calcium and DTPA contents of the CaNa3DTPA. Successive titrations of DTPA (with thorium) and calcium (with DCTA) are carried out using the same sample solution; methyl thymol blue is used as indicator.
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Die isolering van Mo-99 uit klowingsmateriaal vir gebruik in 'n 99Mo/99mTc-generator
- Van der Walt, Tjaart Nicolaas
- Authors: Van der Walt, Tjaart Nicolaas
- Date: 2015-10-07
- Subjects: Radiochemistry , Radiopharmaceuticals , Molybdenum , Ion exchange chromatography , Nuclear medicine
- Type: Thesis
- Identifier: uj:14239 , http://hdl.handle.net/10210/14692
- Description: D.Sc. (Chemistry) , Please refer to full text to view abstract
- Full Text:
- Authors: Van der Walt, Tjaart Nicolaas
- Date: 2015-10-07
- Subjects: Radiochemistry , Radiopharmaceuticals , Molybdenum , Ion exchange chromatography , Nuclear medicine
- Type: Thesis
- Identifier: uj:14239 , http://hdl.handle.net/10210/14692
- Description: D.Sc. (Chemistry) , Please refer to full text to view abstract
- Full Text:
Precise 87Sr/86Sr isotope ratio measurement by quadrupole based ICP-MS after ion exchange separation of Rb for provenance determination of agricultural products
- Authors: Vorster, Clarisa
- Date: 2010-04-08T08:33:41Z
- Subjects: Wine and wine making , Strontium isotopes , Inductively coupled plasma mass spectrometry , Ion exchange chromatography , Provenance trials
- Type: Thesis
- Identifier: uj:6750 , http://hdl.handle.net/10210/3158
- Description: M.Sc. , The strontium isotope ratio 87Sr/86Sr in the wine and soil of four wine-producing regions in South Africa has been determined using quadrupole ICP-MS. Isotope ratio measurements with fairly good precision had been obtained and 87Sr/86Sr ratio values in wine and soil samples were statistically evaluated to determine whether the regions investigated could be distinguished. Statistical interpretation of data revealed that the Robertson wine-producing region could be distinguished from Stellenbosch, Swartland and Walker Bay wine regions on the basis of their 87Sr/86Sr ratio. By using a combination of 87Sr/86Sr and multielement data, canonical discriminant functions with very good classification abilities could be obtained to correctly distinguish between wine and soil samples originating from a specific production region. Due to the isobaric overlap of strontium and rubidium at mass 87, a very good strontium-rubidium separation method had to be developed. The chelating properties of EDTA and DCTA in combination with ion exchange chromatography were explored in order to achieve such a separation. Due to the advanced rubidium separation ability of the developed DCTA elution method, it has been employed in all wine and soil sample preparations. Since chromatographic ion exchange procedures are not capable of removing all the rubidium from the sample matrices, 87Sr/86Sr ratio values were mathematically corrected for residual rubidium using an 88Sr correction. Since strontium isotope ratio measurements require very good precision, it is traditionally determined using TIMS. However, due to the ease of operation, shorter analysis time and widespread availability of quadrupole ICP-MS, the technique was evaluated for its merit for determining strontium isotope ratios. The optimization of acquisition parameters for the determination of the 87Sr/86Sr ratio in wine and soil samples with good precision of below 0.1% RSD has been conducted. Furthermore, selected sample matrix components were assessed as possible matrix interferences as well as for their ability to affect the precision of measurements. It was concluded that with adequate optimization of acquisition parameters, proper sample preparation and reliable mathematical correction of data, 87Sr/86Sr ratio measurements with reasonable precision could be obtained using quadrupole ICP-MS.
- Full Text:
- Authors: Vorster, Clarisa
- Date: 2010-04-08T08:33:41Z
- Subjects: Wine and wine making , Strontium isotopes , Inductively coupled plasma mass spectrometry , Ion exchange chromatography , Provenance trials
- Type: Thesis
- Identifier: uj:6750 , http://hdl.handle.net/10210/3158
- Description: M.Sc. , The strontium isotope ratio 87Sr/86Sr in the wine and soil of four wine-producing regions in South Africa has been determined using quadrupole ICP-MS. Isotope ratio measurements with fairly good precision had been obtained and 87Sr/86Sr ratio values in wine and soil samples were statistically evaluated to determine whether the regions investigated could be distinguished. Statistical interpretation of data revealed that the Robertson wine-producing region could be distinguished from Stellenbosch, Swartland and Walker Bay wine regions on the basis of their 87Sr/86Sr ratio. By using a combination of 87Sr/86Sr and multielement data, canonical discriminant functions with very good classification abilities could be obtained to correctly distinguish between wine and soil samples originating from a specific production region. Due to the isobaric overlap of strontium and rubidium at mass 87, a very good strontium-rubidium separation method had to be developed. The chelating properties of EDTA and DCTA in combination with ion exchange chromatography were explored in order to achieve such a separation. Due to the advanced rubidium separation ability of the developed DCTA elution method, it has been employed in all wine and soil sample preparations. Since chromatographic ion exchange procedures are not capable of removing all the rubidium from the sample matrices, 87Sr/86Sr ratio values were mathematically corrected for residual rubidium using an 88Sr correction. Since strontium isotope ratio measurements require very good precision, it is traditionally determined using TIMS. However, due to the ease of operation, shorter analysis time and widespread availability of quadrupole ICP-MS, the technique was evaluated for its merit for determining strontium isotope ratios. The optimization of acquisition parameters for the determination of the 87Sr/86Sr ratio in wine and soil samples with good precision of below 0.1% RSD has been conducted. Furthermore, selected sample matrix components were assessed as possible matrix interferences as well as for their ability to affect the precision of measurements. It was concluded that with adequate optimization of acquisition parameters, proper sample preparation and reliable mathematical correction of data, 87Sr/86Sr ratio measurements with reasonable precision could be obtained using quadrupole ICP-MS.
- Full Text:
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