Analytical Chemistry Commons^™

Surface Structuring Strategies For Micro-Cantilever Sensing Platforms And Applications For Hydrogen Related Issues, James F. Patton

Doctoral Dissertations

Recent developments in microelectro-mechanical systems have enabled the exploration of transduction modes that involve mechanical energy and are based primarily on mechanical phenomena. As a result an innovative family of chemical and biological sensors has emerged which utilize a transducer in the form of microcantilevers (MCs). MCs offer greater sensitivity than comparable mass-responding sensors due in large part to their small dimension. These low cost devices can be deployed for remote testing, providing real-time information for the analyst. An additional advantage is the ability to employ MCs in an arrayed fashion adding a unique selectivity not available to many sensing …

New Approaches To Electroanalysis Of Metals And Pretreatment Of Biological And Environmental Samples, Stefanie Bragg

Doctoral Dissertations

Biological and environmental sample pretreatment followed by electrochemical sensing are the focus of this dissertation. The Advanced Oxidation Process (AOP) treatment using aqueous hydrogen peroxide and UV irradiation with acid deactivation of the enzyme catalase in blood has been developed and optimized. The kinetics of whole blood AOP in a single-cell reactor was studied, and the effect of pH on the AOP process has been investigated. A new method of dry ashing whole blood has been developed and optimized for trace metal analyses. The new method and subsequent metal analyses in the blood samples has been used to confirm results …

A Novel Approach To Assess Environmental Changes In Marine Ecosystems Via Spectroscopic Analyses Of Microalgae, Rebecca Burke Horton

Doctoral Dissertations

Chemical analyses for environmental monitoring encounter many challenges which are imposed by a multitude of chemically complex and interrelated processes. For such investigations, innovative analytical methodologies must be developed which characterize chemical shifts of key environmental parameters in order to deduce insights into their ecological relevance. This dissertation is driven by an analytical chemistry perspective to develop chemical sensing techniques with the ultimate goal of gaining a deeper understanding of environmental changes and their chemical origins.

In order to overcome limitations inherent to any chemical sensor designed for a specific task, new paths are pursued which are based on the …

Improving Analytical Utility Of Surface Enhanced Raman Spectroscopy Through Unique Lithographic Substrate Development, Sabrina Marie Wells

Doctoral Dissertations

Surface enhanced Raman spectroscopy (SERS) has the potential to be a useful analytical technique due to large signal enhancements. Unfortunately, SERS has several drawbacks, including a lack of reproducibility, which inhibits it from being a practical option. These large signals often arise from “hot spots” of extremely high enhancement on nanofeatured metallic substrates, the most common being comprised of aggregated silver colloid. It is difficult to reproducibly create these hot spots due to the randomness of the colloid substrates. However, through controlled substrate fabrication, many problems associated with SERS analysis can be overcome. Electron beam lithography (EBL) combined with reactive-ion …

The Fabrication And Integration Of Pillar Array Channels For Chip Based Separations And Analysis, Lisa Christine Taylor

Doctoral Dissertations

The fundamental motivations for scaling existing technological platforms down to lab on chip dimensions are applicable in nearly all scientific disciplines. These motivations include decreasing waste, improving throughput, and decreasing time consumption. Analytical tools, such as chromatographic separation devices, can additionally benefit from system miniaturization by utilizing wafer-level fabrication technology, allowing for the rational design and precise control of variables which ultimately affect separation performance. With the use of microfabrication techniques, we have developed an original processing sequence for the fabrication of silicon oxide enclosed pillar arrays integrated within a fluidic channel. These pillar arrays create a highly uniform submicron …

The Itinerant Position Of Yttrium As Evidenced By Carboxylic Acid Extractions, Dustin C Collier

Doctoral Dissertations

The rare-earth elements Y and La-Lu share many similar physical and chemical properties. These similarities are reflected by the difficulty in the complete separation of the rare earths, often requiring hundreds to thousands of stages for the production of pure rare earths. Yttrium, traditionally known to be separated with Ho, has also been observed to be separated with other elements within the lanthanide series, and even outside the bounds of the lanthanide series itself. Previous publications by several authors have indicated that steric factors could influence the position of Y in solvent extractions of the rare earths using carboxylic acid …