Thesis (Ph. D.)--Pennsylvania State University, 1968. / Includes bibliographical references.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants and are mostly products of the incomplete combustion of organic material. PAHs are often found in environmental samples as a complex mixture of isomers. In addition, the same sources that produce complex PAH mixtures also produce other poorly characterized mixtures of organic compounds, commonly referred to as an unresolved complex mixture (UCM), that act as matrix interferences in the chromatographic analysis of samples. Conventional one-dimensional chromatographic techniques, such as gas chromatography coupled to mass spectrometry (GC/MS), are not sufficient for the analysis and quantitation of complex PAH mixtures present in environmental samples due to the high degree of overlap in compound vapor pressures, boiling points, and mass spectral fragmentation patterns. Therefore, the separation and quantitation of complex mixtures of individual PAH compounds in environmental samples requires high chromatographic resolution. Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC��GC/ToF-MS) was used for this study. GC��GC/ToF-MS uses two different gas chromatographic columns, with different separation mechanisms, for the analysis of complex environmental samples. In theory, the peak capacity in GC��GC/ToF-MS is equivalent to the product of the individual peak capacities of each column used. However, in practice, this is rarely obtained because of the existing correlation between the two GC columns used. This dissertation is a compilation of three studies related to analytical method development for the identification and quantitation of complex PAH mixtures (including parent-PAHs, alkyl-PAHs, oxy-PAHs, nitro-PAHs, thio-PAHs, chloro-PAHs, bromo-PAHs and PAHs with molecular weight higher than 300 Da) that may be present in environmental samples using novel column combinations in GC��GC/ToF-MS. The use of a liquid crystal column (LC-50) in the first dimension, followed by a nano-stationary phase column (NSP-35) in the second dimension, was evaluated for the separation of a standard PAH mixture containing 97 different PAHs. Two standard reference materials purchased from NIST (NIST SRM1650b ��� Diesel Particulate Matter and NIST SRM1975 ��� Diesel Extract) were used, after extraction and cleanup, for method validation and comparison between the commonly used non-polar �� polar column combination and the LC-50 �� NSP-35 column combination with high orthogonality. As part of the method validation, an aliquot of NIST SRM1975 (Diesel extract), without sample cleanup was also analyzed for PAHs, showing that the LC-50 �� NSP-35 column combination was accurate (with an average absolute percent difference of approximately 30%) for the identification and quantitation of complex PAH mixtures in environmental samples, with reduced sample preparation prior to analysis. In addition, the LC-50 �� NSP-35 column combination was used for the analysis of PAHs sorbed to polystyrene pellets deployed in an urban bay area as passive water samplers because one-dimensional GC/MS was ineffective due to the presence of a strong unresolved complex mixture (UCM) and matrix interferences. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from Dec. 27, 2012 - June 27, 2013

Tripeptidyl peptidase II (TPPII) is an exopeptidase which cleaves tripeptides from theN-terminus of peptides. The exact functional role of TPPII is still a matter of investigation. Itis believed that the enzyme is primarily involved in intracellular protein degradation, where itcooperates with the proteasome and other peptidases to degrade proteins into free aminoacids. These amino acids can subsequently be used in the production of new proteins. The aimof this work was to express murine wild type TPPII using E. coli and thereafter purify theenzyme from the bacterial lysate. Methods used for the purification included protein andnucleic acid precipitation, anion exchange chromatography, hydrophobic interactionchromatography and gel filtration. The presence of TPPII was determined using activityassay, western blot and SDS-PAGE. Despite the fact that some modification is still needed,the purification yielded a total of 34μg TPPII with a purity of approximately 60%. Thispurified enzyme can be used for future functional characterization.

Thesis (Ph. D.)(Chemistry)--University of Pretoria, 2003. / Includes bibliographical references.

Thesis (MTech. degree in Environmental management.)-Tshwane University of Technology, 2008. / Aims to determine the presence and levels of DDT and its metabolites in human breast milk samples using supercritical fluid extraction and liquid-liquid extraction techniques.

No description available.

Proteome analysis techonologies are commonly employed for discovery-based biomarker identification studies. This thesis aims to help bridge the gap between analytical technology development and clinical application by improving and appling a proteomics workflow for biomarker discovery in congenital urinary tract obstruction (UTO). By accentuating the importance of experimental design, and evaluating the biological relevance of quantitative proteome analyses, the results of this research provide confidence in a number of identified candidate biomarkers of UTO. A sensitive method for quantification of proteome samples was developed using temperature controlled reversed-phase liquid chromatography (TPLC). The TPLC system provides high recovery (> 90 %), as well as high accuracy and precision in estimating the concentration across a number of protein sample types (CV < 10 %). The need for extensive fractionation strategies coupled with LC-MS analysis challenges the throughput of the overall experiment. Development of a dual column LC-MS interface reduced the total analysis time by a factor of 2 over conventional single column LC-MS systems. The system was applied to a quantitative proteome analysis of proximal tubule cells exposed to mechanical stretch, mimicking the conditions they experience during UTO and a urinary exosomal proteome analysis for candidate biomarker identification of this disease. A total of 1636 proteins were identified in the whole cell proteome analysis, of which 317 were found to be significantly altered in abundance. Analysis of the urinary exosomal proteome yielded 318 proteins, of which 189 were found to be altered in abundance due to obstruction. Western blot confirmation of a few select proteins provided backing to the quantitative proteome analysis, while gene ontology and KEGG pathway analysis yielded functional information. The results from the quantitative analyses of the urinary exosomes and proximal tubule cells identified candidates for both diagnosis and prognosis of UTO. In addition, activation of a novel pathway was identified, presenting a potential drug target which could be exploited to improve recovery of children following relief of UTO. This thesis therefore contributes useful technological and methodological advancements towards routine proteome analysis, as well as providing candidate biomarker identification for the leading cause of renal functional loss in children.

Thesis (Ph. D.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 23, 2008) Includes bibliographical references.

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 15, 2008) Vita. Includes bibliographical references.

Thesis (Ph.D)--Baylor University, 2007. / Includes bibliographical references (p. 137-142).