Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: Protein separation. Includes bibliographical references (p. 76-79).

Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 31.

Thesis (M.S.)--Brigham Young University. Dept. of Chemistry and Biochemistry, 2008. / Includes bibliographical references.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: expanded bed chromatography; Pichia pastoris. Includes bibliographical references (leaves 44-45).

Thesis (Ph.D.)--Duquesne University, 2006. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 134-153) and index.

A lack of methods for the separation and determination of air-sensitive Cr(II) and stable Cr(III) complexes in aqueous and organic phase motivated this study. The formation of kinetically stable Cr(III) complexes with common anions was studied using ion chromatography coupled to inductively-coupled plasma emission spectrometry (ICP-OES). Distribution diagrams for the complex species were determined from the results. Estimations of the stability constants were made from these diagrams and compared with stability constants published in the literature. Separation and determination of Cr(II) and Cr(III) and their complexes with PDCA and EDTA in aqueous phase was investigated using ion chromatography. ICP-OES was used for detection purposes. The separation and determination of Cr(II) and Cr(III) complexes with a ligand, bis-(2-decylsulphanyl-ethyl)amine, developed by Sasol Technology (Pty) Ltd., was attempted. The study was undertaken as the Cr(III) complex is used as a catalyst in the trimerisation of ethylene to 1-hexene. The mechanism is still unknown and determining which species are present in the catalytic cycle could clarify which oxidation-reduction couple is involved during the cycle. Reversed phase HPLC was investigated as a possible method for the separation of these complexes. No separation of the species was, however, achieved. / Prof. P.P. Coetzee

M.Tech. / Homoeopathic mother tinctures have an extensive therapeutic history and as the emphasis of health is becoming a worldwide trend, homoeopathic preparations are becoming increasingly popular. However, the quality control and quality assurance still remains a challenge because of the high variability of chemical components involved (Pande and Pathak, 2006). Homoeopathic mother tinctures, singularly and in combinations, contain a copious number of compounds in complex matrices in which no single active constituent is responsible for the overall efficacy. This creates a challenge in establishing quality control standards for raw materials and standardization of finished herbal drugs, resulting in varying standards for these preparations globally (Chitlange, 2008). Various homoeopathic mother tinctures were selected for comparative analysis and consisted of: Artemisia absinthium, Rosmarinus officinalis e foliis recentibus, Sambucus nigra and Salvia officinalis are all manufactured according to the German Homoeopathic Pharmacopoeia method 3a, indicating the use of fresh plant material to produce the mother tincture (German Homoeopathic Pharmacopoeia, 2003). Many factors influence the quality of homoeopathic mother tinctures and many parameters must be met when assessing the quality of these products (Bandaranayake, 2006). Through thin layer chromatography analysis of the selected homoeopathic mother tinctures one is able to determine whether the active components of the samples are present and deduce whether the sample complies with the minimum standard quality stipulated in the German Homoeopathic Pharmacopoeia as well as the Good Manufacturing Practice (Waksmundzka-Hojnos et al., 2008). Samples of each homoeopathic mother tincture, purchased from both local and international manufacturers, were decanted into amber glass bottles, randomized and relabeled. The colour of each sample was assessed and compared to the standard colour stated in the German Homoeopathic Pharmacopoeia. For the thin layer chromatographic analysis, each sample together with reference sample were prepared and developed on both aluminum backed TLC plates and glass backed HPTLC plates. Photographs of the resultant chromatograms were taken, the presence of the active components were identified and the quality of each homoeopathic mother tincture was deduced.

Sugar complexes with anions and cations are reviewed. Evidence is presented for the formation of a complex of stoichiometry 1:1 in aqueous solution between methyl-α-Dglucopyranoside and magnesium perchlorate. The complex may be detected by the method of continuous variations. Measurements of changes in the proton chemical shifts of the glucoside in dauterium oxide, indicate that the complex is probably formed between the vicinal hydroxyl groups at C-2 and C-3 of the pyranoside ring and the hydrated cation. At elevation temperatures there is evidence for the presence of a complex of stoichiometry 2:1. Experiments conducted on cellulose indicate the possible formation of cellulose - magnesium-ion complexes . These complexes provide an explanation for the "protective action" of mEgnesium compounds on the cellulose portion of pulp during alkali-oxygen bleaching.

β-N-methylamino-L-alanine (BMAA) is a non-proteinogenic amino acid associated with human neurodegenerative disease. Due to the cosmopolitan nature of cyanobacteria, detection of BMAA in cyanobacteria has caused concerns about human exposure risk. This study was therefore based on the hypothesis that BMAA poses a health risk to humans either by direct ingestion or by indirect exposure to BMAA from a cyanobacterial source via a freshwater food chain. A validated gas chromatography-mass spectrometry (GC-MS) BMAA analysis method and a confirmatory liquid chromatography-mass spectrometry (LC-MS) method, with improved sensitivity, were developed in addition to a LC-MS/MS method for analyte confirmation. These methods were used to quantify BMAA in South African cyanobacteria, isolated from various potable water reservoirs. The majority of the isolates tested, contained BMAA. Possible human exposure by direct consumption of BMAA released from cyanobacterial blooms was investigated by the development of a robust solid phase extraction (SPE) method used for BMAA concentration and quantification in raw and treated tap water. Despite the use of the SPE method that facilitated the concentration of BMAA from large quantities of water, no free dissolved BMAA was detected in raw or processed fresh water. The fate of exogenous BMAA was therefore investigated firstly by evaluating the efficacy of standard water treatment processes employed in South Africa and secondly by investigating the possibility of BMAA bioaccumulation and biomagnification in aquatic food chains. Standard water treatment processes proved highly efficient at removing free dissolved BMAA, explaining the absence of BMAA in treated tap water. However, the cause of the BMAA absence in raw potable water remained unknown. Uptake of BMAA by model aquatic organisms was investigated in controlled experiments. BMAA uptake was documented in both Ceratophyllum demersum and Daphnia magna, however, BMAA-protein association and biomagnification were not observed in D. magna. BMAA had an inhibitory effect on the oxidative stress enzyme acitivties of both organisms tested (as well as human S9 extracts), resulting in accumulation of detrimental reactive oxygen species (ROS) in the cells. Exposure of crop plants to BMAA in controlled experiments resulted in BMAA uptake, protein association, and subsequent inhibition of the antioxidative enzyme activities. However, BMAA was detected in neither free nor protein-associated form in natural crop plants irrigated with known BMAA-containing bloom water. Post-mortem liver samples of Clarias gariepinus (Catfish) and Crocodylus niloticus (Crocodile), from a natural fresh water ecosystem that experienced frequent cyanobacterial blooms, contained both free and protein-associated BMAA. Higher BMAA concentrations were found in crocodile liver samples compared to fish liver samples, strongly suggesting biomagnification from one trophic level to the next. BMAA concentrations corresponded to crocodile age. This is the first report of bioaccumulation and biomagnification in two trophic levels in a fresh water ecosystem. These findings strongly suggest possible human exposure via aquatic food chains of cyanobacterial origin. Direct BMAA exposure via drinking water is not plausible due to the efficiency of standard water treatment processes to remove BMAA. The use of raw water for agricultural and recreational use, however, remains a problem. The development of management strategies as well as daily tolerable levels for BMAA is urgently required.

Bibliography: pages 117-120. / A series of para-phenyl substituted N,N-dialkyl-N'-benzoylthioureas where para-phenyl substituents are H, Cl, Br, I, NO₂ and OCH₃ and alkyl chains are -CH₂CH₃, -(CH₂)₃CH₃ and and -CH₂C₆H₅ as well as their corresponding neutral bis complexes of type cis [ML₂] where M = Pd(II) and Pt(II) have been prepared and characterized. The structures of these compounds has been studied using high resolution nuclear magnetic resonance technique. Studies were also carried out to investigate possible use of these N,N-dialkyl-N-benzoylthioureas as ligands suitable for the chromatographic separation of Pt(II), Pd(II), Ni(II) and Cu(II). To this end the possible selective extraction of these complexes from acidic aqueous phases was examined. This layer normal phase chromatography has been mainly used, using a variety of organic phases as eluent. A preliminary investigation of the suitability of using normal phase HPLC for the separation of the platinum and palladium complexes was undertaken.