A new theory has been proposed for stationary phase formation of chemically modified chromatographic adsorbents. This theory consists of a model in which the bonded hydrocarbon moiety, silica substrate, and their respective solvation layers all participate in stationary phase formation. Stationary phase formation was found to be dependent on three parameters: (1) Solvent strength of the mobile phase components for the bonded organic moiety and the silica substrate; (2) the type of organic moiety covalently bound to the surface; and (3) the bound moiety density or surface coverage. Binary aqueous-organic mobile phases were investigated for LiChrosorb RP-8 and RP-18. For RP-8 the solica substrate played a more important role in stationary phase formation. Whereas, for RP-18 the longer bound hydrocarbon chain dominated stationary phase formation. With different organic modifiers in the mobile phase, the modifier with the larger solvent strength for the bound hydrocarbon was selectively enriched in the stationary phase solvation layer for RP-18. Ternary mobile phase systems were also investigated for RP-18. The second modifier was found to exert a large influence on stationary phase formation. Temperature's role in stationary phase formation was studied with a ternary mobile phase of 40/45/15 methanol, water, THF with RP-18. In this specific case, changing the temperature of the system did not impact on stationary phase formation. A new type of column structure was investigated. This structure involved a totally porous silica gel as compared to a column packed with totally porous silica microparticles. These silica gel columns were characterized both thermodynamically and kinectically. Under Normal Phase chromatographic conditions the silica gel column was found to have a higher selectivity but poorer efficiency for the separation of aniline from nitrobenzene than a packed column. The silica gel can be chemically modified by silane reaction and its bonded phase characteristics were investigated. The gel also showed ion-exchange properties which were investigated using sodium nitrite.

Environmental and safety concerns have prompted an active quest for ―green‖ alternatives to / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009.

No description available.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2016. / The presence of estrogenic hormones in the environment has been a subject of concern in recent years; they have been classified as “emerging pollutants” and may pose a potential risk for human consumption. Hormones have been detected in ground and surface water at low concentrations. These compounds contaminate the surface and ground water via waste water treatment plants (WWTP) and may elicit endocrine disruption to organisms. Because these compounds are available at low concentration, robust analytical methods are required to quantify these compounds in water and environmental samples. The common method for the analysis of hormones in water samples is Gas Chromatography (GC) coupled to Mass Spectrometer (MS). The challenge with GC-MS is the required lengthy derivatisation step that involves toxic chemicals. The first part of this case study was to develop a method to determine trace concentrations of the Estrone (E1), 17α-Estradiol (E2α), 17 β-Estradiol (E2β) and 17α-Ethinylestradiol (EE2) hormones using Ultra-Fast Liquid Chromatography Mass Spectrometry (UFLC-MS-MS). Using the developed method, the second part of the case study was to determine the concentrations of the hormones in raw and potable water samples from the Vaal River catchment area in the South of Johannesburg, South Africa. Analytes were extracted by solid phase extraction (SPE C18 Sorbent, 200 mg/6mℓ cartridges) and subjected to Ultra-Fast Liquid Chromatography coupled to Mass Spectrometer (UFLC-MS-MS) for identification and quantification. Optimum SPE parameters were 1000 mℓ of sample percolated, at flow rate of 10 mℓ/min, sample pH of above 7, 7.5 mℓ of methanol as elution solvent followed by solvent reduction to 250 μℓ. The limits of quantification were in a range of 0.24 to 0.32 ng/ℓ for all analytes. Accuracy was 95.6, 93.8, 97.6 and 100.9% for 17α-Ethinylestradiol, 17α-Estradiol, 17β-Estradiol and estrone, respectively. In raw water samples taken during the rainy wet season, estrone was detected at concentrations of 0.90 and 4.43 ng/ℓ. However, drinking water samples no presence of hormones with the exception of M-B12 sample point where the estrone amount of 2.88 ng/ℓ was detected. This is potentially due to fact that conventional water treatment plants are able to remove the compounds during water purification process depending on the concentration levels. / LG2017

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%.

Membrane chromatography is a promising process for the isolation, purification, and recovery of proteins, enzymes, and nuclear acids. Comparing with traditional beads column chromatography, membrane chromatography can faster, easier and cheaper to mass-produce. And also, it is easy to set up and scale up. In this thesis, we are trying to study the performance of membrane chromatography, and the mixture of HSA and chicken egg white is used as an example. We are investigating the purification of Human serum albumin (HSA) from chicken egg white in terms of precondition, dilution, purification method, product recovery, product purity and product cost. HSA, is a very important clinical protein. In order to obtain low cost, high efficiency and less risk HSA, recombinant DNA technology is used. Many kinds of host organism have been used to produce recombinant HSA (rHSA). In this thesis, a kind of ion-exchange membrane (Mustang Q membrane capsule) chromatography was used. The membrane capsule is disposable because it is designed for use in pharmaceutical production. For this project, a cleaning method was used which made the membrane capsule reusable. Washing with 4 mL 1 M NaCl and 4 mL NaOH was sufficient for this purpose. Since the egg white protein solution was very viscous, it needs to be diluted before loaded on FPLC. Dilute experiment was done to find the best dilution level. In this thesis, we found that 5 times dilution was best not only for high efficiency but also for FPLC operation. After getting the basic conditions, some purification experiments were done to find the optimal operation condition to purify HSA form chicken egg white protein solution by changing buffer pH, salt concentration in elution buffer and gradient used to elute proteins. The best purification condition for loading buffer is Tris-HCl buffer A (4.75g/L, pH 9.5) and the elution buffer is Tris-HCl buffer A + 0.2M NaCl. The purity of HSA recovered was 93% on the Mustang Q membrane capsule at 1 ml/min when the mixture of HSA and chicken egg white was diluted 10 times. And the yield was 85%. The impurity is probably ovoglobulin as suggested by the result of SDS-PAGE, whose molecular weight is close to 40kd. To characterize the separation capability of the Mustang Q membrane capsules, equilibrium adsorption and breakthrough curve studies were made using bovine serum albumin (BSA). 1mg/mL BSA solution was used to get the breakthrough curve with different flow rate ranging from 1 to 4 ml/min. With a flow rate is 1 ml/min, breakthrough curve were obtained with different concentrations of BSA ranging from 1 to 16 mg/mL. The dynamic binding capacity was found to be from 9.1 to 119.1 mg/mL. The equilibrium adsorption isotherm showed Langmuir isotherm behavior with dissociation constant and a maximum adsorption capability. According to the result of isotherm adsorption, a multi-plate mathematical model was used to get the theoretical breakthrough curve. By fitting the theoretical breakthrough curve to the experimental breakthrough curve, constants in the multi-plate model were obtained and were used to estimate the axial dispersion coefficient of the membrane capsule. The estimated axial dispersion coefficient of 2.45*10-6 cm2/s is very small which means that the axial ispersion is not significant. The adsorption process is therefore controlled by radial radius dispersion or film dispersion.

No description available.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O FÃsforo à um dos elementos essencial no corpo humano requerido pelas cÃlulas para o seu funcionamento; sendo o maior constituinte dos ossos do corpo humano, na forma de fosfato de cÃlcio. A determinaÃÃo de fÃsforo pode ser efetuada utilizando-se diferentes tÃcnicas tais como espectrofotometria de absorÃÃo molecular, cromatografia iÃnica, fosforescÃncia, espectrometria de emissÃo atÃmica, entre outras. Este trabalho tem como objetivo desenvolver uma metodologia para determinaÃÃo de fÃsforo em digeridos de amostras orgÃnicas por espectrometria de emissÃo Ãptica com plasma indutivamente acoplado. A metodologia desenvolvida estudou quatro linhas de emissÃo deste elemento e duas configuraÃÃes instrumentais, axial e radial. Somente os comprimentos de onda 213,617 e 214,914nm apresentaram sensibilidade adequada para o estudo. A faixa linear investigada foi de 50 a 300 mg.L-1 . A investigaÃÃo do efeito interferente foi realizado com os metais alcalinos (Na e K) e alcalinos terrosos (Ca e Mg) no sinal de fÃsforo. Mostrando-se aditiva para todos os metais estudados, com aumento do sinal em atà 50% para o potÃssio como interferente. Para resoluÃÃo desse efeito interferente investigou-se o aumento da potÃncia da radiaÃÃo do plasma gerado e uso de padrÃo interno. O uso do padrÃo interno mostrou-se mais adequado, no caso o Sc, com correÃÃes de 90 % de reduÃÃo da interferÃncia. A metodologia desenvolvida foi avaliada em amostras certificadas interlaboratoriais e os resultados obtidos foram compatÃveis com erros inferiores a 10%. O teor de fÃsforo foi determinado em amostras de banana submetidas a um tratamento de fertilizaÃÃo, sendo os valores obtidos na ordem de 765 e 1.167 mg.L-1 / The Phosphorus is an essential element for in body human required by cells for the operation; is the largest constituent of the bones of the human body in the form of calcium phosphate. The determination of phosphorus can be using different techniques is like Molecular Absorption Spectrophotometry, Ion Chromatography, Phosphorescence, Atomic Emission spectrometry, among others. This work has a goal to develop a methodology for determination of phosphorus in digest of organic samples by optical emission spectrometry with plasma inductive coupled. The methodology developed studies 4 lines of emission of this element and two instrumental settings, axial and radial. Only a wavelength 213.617 and 214.914nm had sensitivity suitable for the study. The linear range investigated was 50 to 300 mg. L-1. The investigation of the interference effect was studied by alkali metals (Na and K) and alkali earth (Ca and Mg) in the sign of phosphorus. The positive interference was obtained for all metals investigated with increase in the signal in up to 50% for potassium with interference. To resolve this effect interfering was investigated the increased power of radiation from the plasma generated and use of internal standard. The use of internal standard has been more appropriate, in case the Sc, with corrections of 90% reduction of interference. The methodology developed was evaluated in interlaboratory certified samples and the results were compatible with errors less than 10%. The content of phosphorus was determined in samples of banana subjected to a treatment of fertilization, and the values obtained in the order of 765 and 1.167mg.L-1

Silk fibroin from silkworm cocoons is found in numerous applications ranging from textiles to medical implants. Its recent adoption as a biomaterial is due to the material's strength, biocompatibility, self-assembling behavior, programmable degradability, optical clarity, and its ability to be functionalized with antibodies and proteins. In the field of bioengineering it has been utilized as a tissue scaffolding, drug delivery system, biosensor, and implantable electrode. This work suggests a new application for porous silk in a microscale chromatography column. We demonstrate in situ cryotropic polymerization of highly porous structures in microscale geometries by freezing aqueous silk with a solvent. The resulting cryogels are experimentally characterized using flow parameters common in chromatography design; tortuosity, global pressure drop, pore diameter, and porosity. These empirical parameters are put into porous flow models to calculate an order-of-magnitude increase in functional surface area over the blank capillaries and packed-sphere columns used in traditional designs. Additionally, the pressure requirements to produce relevant flow rates in these structures are found not to threaten the integrity of microfluidic seals or connectors.

Thesis (Ph. D.)--Georgia State University, 2007. / Title from file title page. Gabor Patonay, committee chair; A.L. Baumstark, G. Davon Kennedy, Gregg Pratt, committee members. Electronic text (170 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed Dec. 10, 2007. Includes bibliographical references.