Browsing by Subject "Mercury."
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Item Development and application of high-throughput sample preparation methods for solid matrices.(2014-09-05) Aguilar Lázaro, Lissette.; Usenko, Sascha.; Ecological, Earth, and Environmental Sciences.; Brooks, Bryan W.; Oziolor, Elias M.; Matson, Cole W.; Robinson, Eleanor M.; Trumble, Stephen John.; Williams, E. Spencer.; Subedi, Bikram.; Bigorgne, Emilie.; Horstmann-Dehn, Lara.; Baylor University. Institute of Ecological, Earth and Environmental Sciences.This research presents the development and application of high-throughput sample preparation methods for the analysis of organic and inorganic contaminants from solid samples. The approach presented evaluates conventional methods to identify potential areas of improvement. In this sense, conventional methods serve as a framework for the development of high-throughput sample preparation methods. In general, improvements include expansion of target analyte list thereby increase the environmental applicability, reduction of sample preparation steps, and as a result, reduction of sample preparation time. The analytical bottleneck is often associated with sample preparation, especially in the analysis of organic contaminants from environmental samples. Many environmental analytical chemistry methods can be broken down into one or more sample preparation steps followed by one or more chemical analysis steps. Improvement of historical methods has focused on the development of advance instrumentation (i.e. focusing on the chemical analysis). However, recent efforts have focused on the overall reduction of time and/or steps associated with sample preparation. For example, post-extraction cleanup adsorbents can be incorporated into the pressurized liquid extraction step to perform a selective pressurized liquid extraction (SPLE). SPLE methods significantly reduced sample preparation time, solvent requirements, and waste production. Specific examples presented in this dissertation include: 1) the development and application of SPLE methods for the analysis of organic contaminants from sediments and biological tissues; 2) the development and application of a simplified acid digestion method for the analysis of mercury and selenium in rare samples of Pacific walrus (Odobenus rosmarus divergens) muscle (L. dorsi). These examples illustrate the approach for the development of high-throughput sample preparation methods that have successfully combined techniques into a single method, and/or eliminated post-extraction cleanup steps. The availability of these methods increases laboratory’s capacity and preparedness to analyze rapidly large volumes of samples. These methods could find use in routine analysis and monitoring studies of environmental samples, food and pharmaceutical industries, agriculture, toxicology studies, and forensic sciences among others. Lastly, this dissertation discusses a few opportunities that lay ahead for improvement and development in sample preparation.Item Synthesis and coordination studies of [(diphenylphosphino)methyl]pyridine coordination compounds.(2013-09-16) Padron, Daniel A.; Klausmeyer, Kevin Kenneth, 1969-; Chemistry and Biochemistry.; Baylor University. Dept. of Chemistry and Biochemistry.The coordination properties of the bifunctional ligand 2-[(diphenylphosphino)methyl]pyridine, its two corresponding oxides, and the ligand 4-[(diphenylphosphino)methyl]pyridine towards different transition metal salts are described. The ligand 2-[(diphenylphosphino)methyl]pyridine and both of its oxide derivatives, P oxide and N,P dioxide, showed preference to behave in a chelating mode, although bridging behavior was also observed in a few cases such as when silver was the metal center involved. Unusual polymeric structures were obtained demonstrating the functionality of these ligands in the multidimensional network construction. Due to opposite positioning of its donor centers, the ligand 4-[(diphenylphosphino)methyl]pyridine showed an inclination to behave as a bridge, usually in a head-to-tail fashion, rather than as a chelate. The crystal structures were determined by single-crystal X-ray crystallography. With the use of this technique several supramolecular interactions were identified. It was demonstrated that, even though these interactions are rather weak, they play an important role in the control of the overall structure of the molecular array. The anion present and the solvent system used to grow the crystals studied herein were variables with heavy influence in the resulting molecular structures. The synthesized novel complexes were fully characterized by elemental analysis, UV-visible spectroscopy, FT-IR spectroscopy and multinuclear NMR spectroscopy, where the technique was appropriate.