Analytical Chemistry Commons^™

Facilitating Conceptual Learning In Quantitative Chemistry, Sarah R. Johnson

Electronic Theses and Dissertations

Traditional chemistry laboratory courses have a manual consisting of “step-by-step” experiments; instructions are given to complete experiments, requiring minimal information/concepts processing to be successful. This experience leaves students unprepared for the real-world, where critical thinking skills are needed to conduct research. This study focused on building analytical techniques, conceptual knowledge, and critical thinking skills used to solve research problems. A new quantitative chemistry laboratory manual was developed to transition students from traditional to inquiry-based experiments, requiring analytical method development. Data showed students having less difficulty using the new manual (0.8281 average difficulty) on method development exam questions and experiments, compared …

Development Of Electrochemical Sensors Suitable For In Vivo Detection For Neurotransmitters, Mengjia Hu

Graduate Theses and Dissertations

The electrochemical method of redox cycling was exploited to achieve new discoveries in neurotransmitter detection and to advance its suitability toward in vivo use. Redox cycling has advantages in signal amplification, selectivity of species based on their electrochemical reaction mechanisms, and limited or no background subtraction. Distinction of dopamine from norepinephrine in a mixture with an electrochemical method at unmodified electrodes was demonstrated for the first time in vitro. This ability resulted from a series of fundamental studies of redox cycling behavior of the catecholamines (dopamine, norepinephrine and epinephrine) using different electrode configurations. Taking advantage of the ECC’ mechanism associated …

Lipid Content And Biomass Analysis In Autotrophic And Heterotrophic Algal Species, Addie M. Lauder, Daniel P. Jones, Thomas E. Walker, Todd Allen

Montview Journal of Research & Scholarship

Biofuels are a form of renewable energy derived from living matter, typically plants. The push for biofuels began in order to decrease the amount of carbon dioxide (CO2) released into the atmosphere, as biofuels are essentially carbon neutral. The idea is the same amount of CO2 the plants took in to perform photosynthesis will then be released in the burning of the biofuels. Algae is an excellent source of biofuels because it grows quickly and is versatile in terms of the type of fuel it can produce. The two most common mechanisms for algae growth are heterotrophic or photoautotrophic. Heterotrophically …

Binding Of Oxygen To Human Hemoglobin Within The Erythrocyte Using Icam Spectrophotometry, Kyle K. Hill

Department of Chemistry: Dissertations, Theses, and Student Research

Many of the spectrophotometric techniques used to determine the properties of intracellular human hemoglobin cannot be utilized due to the turbidity of erythrocyte suspensions. An Integrating Cavity Absorption Meter, or ICAM, allows for absorption measurements of strongly scattering samples in the visible-light region of the spectrum. The spectrum of oxygenated hemoglobin within erythrocytes is significantly different from the absorption spectrum of oxygenated hemoglobin in solution. Studies of the oxygen binding to hemoglobin in erythrocytes allowed the four sequential binding constants (Adair constants) to be determined and compared with those of hemoglobin in solution. The Adair constants for hemoglobin in solution …

Time Travel: Scientists And Their Contributions Towards The Discoveries Of The Atom And Atomic Properties, Austin Wright

GS4 Student Scholars Symposium

The discovery of the atom and its associated components and properties paved the way for laying the foundation of chemistry related knowledge. However, the historical discoveries of each individual component are often forgotten or ignored due to the students‰Ûª innate belief of it ‰Û÷being difficult‰Ûª to remember such specific information. To assist students with grasping the properties of the atom and its components, a timeline-assisted chronology of atomic discoveries was created. Our objective is to present the scientists, with their individual contributions to atomic theory, along with the year it was discovered in an interactive manner. Using this timeline, students …

Photocatalytic Properties Of G-C3n4–Tio2 Heterojunctions Under Uv And Visible Light Conditions, Rachel Fagan, Declan Mccormack, Steven J. Hinder, Suresh Pillai

Articles

Graphitic carbon nitride (g-C3N4) and titanium dioxide (TiO2) were chosen as a model system to investigate photocatalytic abilities of heterojunction system under UV and visible light conditions. The use of g-C3N4 has been shown to be effective in the reduction in recombination through the interaction between the two interfaces of TiO2 andg-C3N4. A simple method of preparing g-C3N4 through the pyrolysis of melamine was employed, which was then added to undoped TiO2 material to form the g-C3N4–TiO2 system. These materials were then fully characterized by X-ray diffraction (XRD), Brunauer Emmett Teller (BET), and various spectroscopic techniques including Raman, X-ray photoelectron …

Photocatalytic Reduction Of Fumarate To Succinate On Zns Mineral Surfaces, Ruixin Zhou, Marcelo I. Guzman

Chemistry Faculty Publications

The reductive tricarboxylic acid (rTCA) cycle is an important central biosynthetic pathway that fixes CO₂ into carboxylic acids. Among the five reductive steps in the rTCA cycle, the two-electron reduction of fumarate to succinate proceeds nonenzymatically on the surface of photoexcited sphalerite (ZnS) colloids suspended in water. This model reaction is chosen to systematically study the surface photoprocess occurring on ZnS in the presence of [Na₂S] (1–10 mM) hole scavenger at 15 °C. Experiments at variable pH (5–10) indicate that monodissociated fumaric acid is the primary electron acceptor forming the monoprotic form of succinic acid. The following …

The Effect Of Nitrate On The Release Of Glucose Into The Hemolymph Of Crayfish, Procambarus Clarkii, Alec R. Flores, Lee Kats, David Green, Gary Bucciarelli

Seaver College Research And Scholarly Achievement Symposium

Pollutants can change the behaviors of invertebrate stream animals. The level of one common pollutant, nitrate (NO3), has been rising in many local rivers and streams throughout the United States due to increases in anthropogenic sources. Nitrate, heavily regulated for its toxic effects to human health, namely the aiding in the development of cancer, also dangerously affects aquatic species by converting oxygen-carrying pigments to forms that are incapable of carrying oxygen. To understand the stress effects of ambient nitrate exposure on P. clarkii, we collected hemolymph samples from red swamp crayfish (Procambarus clarkii) over a 48-hour period after exposure to …

Advances In Solid Phase Microextraction For The Analysis Of Volatile Compounds In Explosives, Tire Treatments, And Entomological Specimens, William D. Kranz

Open Access Dissertations

Solid phase microextraction is a powerful and versatile technique, well-suited to the analysis of numerous samples of forensic interest. The exceptional sensitivity of the SPME platform, combined with its adaptability to traditional GC-MS systems and its ability to extract samples with minimal work-up, make it appropriate to applications in forensic laboratories.

In a series of research projects, solid phase microextraction was employed for the analysis of explosives, commercial tire treatments, and entomological specimens. In the first project, the volatile organic compounds emanating from two brands of pseudo-explosive training aids for use in detector dog imprinting were determined by SPME-GC-MS, and …

Folate-Peg-Histidine For Use In Detection, Capture, And Analysis Of Fr+ Cells, Sean Dwyer

All Capstone Projects

Folate receptor alpha is a membrane-bound protein displaying high affinity for folic acid. This receptor serves as a receptor-mediated transport system of folic acid into cancer and cells associated with inflammation (e.g., macrophages). Folate is a basic component of cell metabolism in both the synthesis of DNA and proteins, which is hypothesized to be necessary for maintaining adequate processes during increased metabolic demand. Interestingly, most normal cells in the body have little or no high affinity folate receptor alpha. Based on these attributes, folate based drug delivery, imaging systems, and diagnostic systems are in several stages of development worldwide. To …

Feasibility Study Of Waste Isolation And Characterization By Instrumental Methods, Janith A. Wiehe-Wazio

All Capstone Projects

The original focus of this project was to develop an in house procedure for the recovery of commonly used science laboratory solvents consisting of Acetone, Ethyl (Ethanol) Alcohol, Hexane, Methanol and Hydrochloric Acid from everyday laboratory waste. However, the projects scope shifted a little further back to basics when it was discovered that Laboratory Waste Safety and Accounting practices were insufficient. It was assumed that identification of waste products was being recorded accurately. It became apparent with the very first waste bottle analysis that chemicals recorded on the standardized waste log sheets were not always what was in the waste …

Purification And Preparation Of Intrinsically Disordered Proteins For Nmr Spectroscopy, Kyle Chamberlain

Open Access Theses

NMR spectroscopy has recently become a promising field for protein characterization and dynamic studies. As the technology and pulse sequences improve for tracking proteins, a greater demand for developing effective purification protocols to produce NMR grade protein samples have arisen. This thesis explores two proteins: histone H4 tail and Mucin 1; Two very different proteins that require different methods of expression and purification to achieve a high enough yield for NMR analysis. H4 is a water soluble protein that weighs ~2.7 kDa, and has no extinction coefficient. Since the protein is too small for many methods of expression and purification, …

Targeted Metabolomics On The Shikimate And Aromatic Amino Acid Biosynthetic Pathways, Robert E. Wheeler

Open Access Theses

The shikimate and aromatic amino acid biosynthesis pathways are some of the most studied biosynthetic pathways in nature due to their fundamental importance. Interest in this field stems from synthesis of the essential amino acids, tryptophan, tyrosine and phenylalanine. The pathways also are important as generating the precursors of thousands of secondary metabolites and lignin. Inhibiting the pathway has led to discovery of herbicides, pesticides as well as tuberculosis drugs. However there is currently a lack of a comprehensive targeted method for detecting and quantifying the majority of the intermediates in these pathways. Often multiple extraction and detection methods are …

Direct Drug Screening And Lipid Profiling Using Ambient Mass Spectrometry, Yuan Su

Open Access Dissertations

Mass spectrometry (MS) stands in an outstanding position in analysis of biological specimens owing to its abundant structural information, high accuracy, incomparable sensitivity, high speed, and the large variety of its applications. The ion source, an instrumental part for converting the analyte into ions, has played an important role in analyzing biological specimens by MS. However, the performance of conventional spray-based ionization methods always suffers from chemical interferences derived from complex biological matrices. A series of sample extraction, purification, and separation steps is required before the ionization, so as to ensure excellent performance of MS analysis. In order to simplify …

Alignment For Comprehensive Two-Dimensional Gas Chromatography (Gcxgc) With Global, Low-Order Polynomial Transformations, Davis Rempe, Stephen Reichenbach, Stephen Scott

UCARE: Research Products

As columns age and differ between systems, retention times for GC x GC may vary between runs. In order to properly analyze chromatograms, it is often desirable to align chromatographic features between chromatograms. This alignment can be characterized by a mapping of retention times from one chromatogram to the retention times of another chromatogram. Alignment methods can be classified as global or local, i.e., whether the geometric differences between chromatograms are characterized by a single function for the entire chromatogram or by a combination of many functions for different regions of the chromatogram. Previous work has shown that global, low-degree …

Ruthenium-Catalyzed Amination Of Secondary Alcohols Using Borrowing Hydrogen Methodology, Kostiantyn O. Marichev, James M. Takacs

Department of Chemistry: Faculty Publications

A new ruthenium complex catalyzes the amination of primary and secondary alcohols and the regioselective mono- and sequential diamination of diols via the borrowing hydrogen pathway. Several variations on new intra- and intermolecular cyclizations of aminoalcohols, diols and diamines lead to heterocyclic ring systems.

The Marine Cyanate Cycle, Brittany Widner

OES Theses and Dissertations

Cyanate (OCN-) is a reduced nitrogen compound with the potential to serve as a nitrogen and carbon source for marine microbes. Evidence from genomes and culture studies indicated that several marine cyanobacterial groups, including representatives of the globally important genera Synechococcus and Prochlorococcus, might be capable of cyanate assimilation. However, prior to this study, the distribution, bioavailability, and production pathways of cyanate were unknown in natural systems due to the absence of a sensitive cyanate assay; and the ability of organisms to assimilate cyanate on relevant timescales was unknown because we lacked a suitable tracer for measuring uptake. I developed …

Αβ-Peptide Mimics Of Z-Domain Peptides, Samuel H. Gellman, James W. Checco

Department of Chemistry: Faculty Publications

Described are αβ-peptide mimics of Z-domain scaffold pep tides, methods of making them, and methods of using them. The αβ-peptide mimics include B-amino acid residues and, optionally, disulfide bonds to stabilize the conformation of the mimics. The compounds may be truncated as compared to conventional Z-domain scaffold peptides and are resistant to proteolytic degradation due to the presence off-amino acid residues. The mimics can be made so as to bind selectively to a desired target.

An Effective Method For The Preparation Of High Temperature Stable Anatase Tio2 Photocatalysts, Rachel Fagan, Declan Mccormack, Suresh Pillai, Damian Synnott

Articles

An efficient, rapid and straightforward method for the preparation of nitrogen and fluorine (N, F) codoped high temperature stable anatase using a microwave pre-treatment is reported. Using a single source, ammonium fluoride (NH₄F) for both nitrogen and fluorine, effective doping of the precursor titanium isopropoxide (TTIP) was possible. These samples were characterised for their structural and optical properties using X-ray diffraction (XRD), Fourier transform IR (FTIR), Raman spectroscopy and UV-vis spectroscopy. In terms of the anatase to rutile transition enhancement using a novel microwave assisted technique, the sample prepared in a composition of 1:8 TiO₂: NH …

Characterization Of Α‑Synuclein Multimer Stoichiometry In Complex Biological Samples By Electrophoresis, Bryan A. Killinger, Anna Moszczynska

Pharmaceutical Sciences Faculty Publications

The aberrant aggregation of α-synuclein in the brain is a hallmark of Parkinson’s disease (PD). In vivo soluble α-synuclein occurs as a monomer and several multimers, the latter of which may be important for the biological function of α-synuclein. Currently, there is a lack of reproducible methods to compare α-synuclein multimer abundance between complex biological samples. Here we developed a method, termed “multimer-PAGE,” that combines in-gel chemical cross-linking with several common electrophoretic techniques to measure the stoichiometry of soluble α-synuclein multimers in brain tissue lysates. Results show that soluble α-synuclein from the rat brain exists as several high molecular weight …

Electrochemical H2O2 Sensor Based On The Co-Immobilization Of Phosphmolybdic Acid And Graphene On Pedot Film Electrode With Nafion, Hao-Xian Zhou, Jun-Ming Zhang, Zhi-Yu Qu, Pan-Yu Zhang, You-Jun Fan

Journal of Electrochemistry

With a glassy carbon electrode (GCE) as the substrate, the poly(3,4-ethylenedioxythiophene) (PEDOT) film electrode was prepared through the electrochemical polymerization method, then a novel non-enzymatic electrochemical H₂O₂ sensor was fabricated by co-immobilizing phosphomolybdic acid and graphene with Nafion on the PEDOT/GCE electrode. The modified electrodes were characterized by scanning electron microscopy (SEM), while the responsive properties of the sensor to H₂O₂ were investigated by cyclic voltammetry and chronoamperometry. The results demonstrated that, under the optimized conditions, the sensor exhibited good electrocatalytic performance for H₂O₂ reduction. The current response of the sensor …

Adsorption Behavior Of Rhodamine 6g On Silver Surfaces Studied By Electrochemical Surface-Enhanced Raman Spectroscopy, Chan-Juan Chen, Cheng Zong, Guo-Kun Liu, Bin Ren

Journal of Electrochemistry

Rhodamine 6G (R6G) is one of the most common probe molecules employed in single molecule surface-enhanced Raman spectroscopy (SM-SERS). The study in adsorption behavior of R6G will help understand the interactions between R6G and surface. In this paper, we used electrochemical surface-enhanced Raman spectroscopy (SERS) to study the potential-dependent adsorption behavior of R6G on silver electrodes. Our results show that when the potential moved negatively, the orientation of R6G on silver surface changed from vertical to inclined adsorption. This result indicates that the abnormal SM-SERS spectra of R6G observed in the former SM-SERS studies from other research groups are due …

Electrochemical Detection Of Hydrogen Peroxide At Aunps Modified Electrode Using P-Hydroxyphenylboronic Acid As A Precursor, Chun-Yan Wang, Xiao-Qiu Liu, Ying-Xin Qi

Journal of Electrochemistry

We developed a new method for electrochemical detection of hydrogen peroxide (H₂O₂) based on boronate oxidation of p-hydroxyphenylboronic acid. This method using p-aminophenol which is produced from the reaction of H₂O₂ and p-aminophenylboronic acid as a well electrochemical probe, combined with a gold nanoparticles (AuNPs) modified electrode for an indirect detection of H₂O₂. Because of the large surface area and enhanced electrocatalytic behavior by the AuNPs modified electrode, the detection sensitivity was improved. The method could detect H₂O₂ in the concentration range of 1 ~ 100 …

Fabrication Of Riboflavin Electrochemical Sensor Based On Au Nanoparticles/Polydopamine/Carbon Nanotubes Modified Glassy Carbon Electrode, Hua-Ping Peng, Mei-Ling Yu, Xin Liu, Pan Liu, Wei Chen, Ai-Lin Liu, Xin-Hua Lin

Journal of Electrochemistry

A novel electrochemical platform for the high sensitivity detection of riboflavin was constructed by Au nanoparticles/polydopamine/carbon nanotubes (Au-PDA-MWCNTs) nanocomposite modified glassy carbon electrode. The Au-PDA-MWCNTs nanocomposite was synthesized by in situ reduction method. The characteristics of the as-prepared Au-PDA-MWCNTs nanocomposite modified electrodes were investigated by using UV-Vis spectroscopy, scanning electron microscopy (SEM) and electrochemical methods. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study the electrochemical behavior of riboflavin (RF) at Au-PDA-MWCNTs nanocomposite modified electrodes. The results demonstrated that the present electrochemical sensor exhibited a wide linear range from 5×10^-9 mol•L^-1to 1×10^-5 mol•L …

Variable Van Der Waals Radii Derived From A Hybrid Gaussian Charge Distribution Model For Continuum-Solvent Electrostatic Calculations, Renlong Ye, Xuemei Nie, Chung Wong, Xuedong Gong, Yan Wang, Thomas Heine, Baojing Zhou

Chemistry & Biochemistry Faculty Works

We introduce a hybrid Gaussian charge distribution model (HGM) that partitions the molecular electron density into overlapping spherical atomic domains. The semi-empirical HGM consists of atom-centered spherical Gaussian functions and discrete point charges, which are optimized to reproduce the electrostatic potential on the molecular surface as well as the number of electrons in atom-centered and certain off-atom-centered spherical regions as closely as possible. In contrast, our previous Gaussian charge distribution model [J. Chem. Phys. 129, 014509 (2008)] contained only spherical Gaussian functions and was not required to reproduce the number of electrons in off-atom-centered regions. Variable van der Waals (vdW) …

The Effects Of Rain On Elemental Transport In Soils, Laura Schoenfeld

STAR Program Research Presentations

Mini Landscape Evolution Observatory (miniLEO) is a model landscape slope composed of granular basalt used to conduct small scale experiments to more clearly understand how elemental transport occurs during simulated rain events. For this experiment, rain events occurred three times a day in two hour increments at a rate of 30 mm/hr for 14 days to determine if exchangeable ions and target elements dissolve over time. An auto sampler collected the waterseepage every half hour at the bottom of the slope of miniLEO. Each seepage sample was tested or the amount of elements present in solution using ion chromatography and …

Development And Validation Of Uplc/Ms/Ms Methods For Quantification Of Gangliosides In The Clinical Study Of Ganglioside Gm3 Synthase Deficiency, Qianyang Huang

ETD Archive

Gangliosides are a large subclass of glycosphingolipids that structurally characterized by the addition of mono- or poly-sialyated carbohydrate moieties onto the ceramide scaffold. They are presented at significant abundance in the central nervous system of vertebrates. Their interactions with trans-membrane receptors, especially receptor tyrosine kinase, are believed to play critical roles in modulating signal transduction events during cell proliferation, differentiation, migration, and adhesion. Furthermore, the disruption and dysfunction on their metabolism have been found to be associated with various neurodegenerative disorders, such as Alzheimer disease, Parkinson’s disease, and GM3 synthase deficiency. GM3 synthase deficiency (GSD) is a newly identified neurological …

Study Of Electron Transfer Through The Reductase Domain Of Neuronal Nitric Oxide Synthase And Development Of Bacterial Nitric Oxide Synthase Inhibitors, Yue Dai

ETD Archive

Crystal structure of neuronal Nitric Oxide Synthase reductase (nNOSr) implies that large-scale domain motion is essential for electron transfer. However, the details are not well understood. To address this, we generated a functioning “Cys-lite” version of nNOSr and then replaced the nNOSr Glu816 and Arg1229 residues with Cys in the FMN and FAD domains (CL5SS) in order to allow cross-domain disulfide bond formation under pH 9 or to cross-linking using bis-maleimides. Cross-linked CL5SS exhibited a =95% decrease in cytochrome c reductase activity and reduction of the disulfide bond restored the activities. The results demonstrate that a conformational equilibrium involving FMN …

Application Of Advanced Analytical Technologies To Drug Development Studies And Cancer Detection, Ramakrishna Reddy Voggu

ETD Archive

In the past decade, bioanalytical method development has become an integral part of the clinical diagnosis, biomarker discovery, and drug discovery and development. The new and emerged bioanalytical techniques allow the quantitative and qualitative analysis of bio molecules with remarkably high sensitivity and specificity. Specifically, these bioanalytical methods based on LC-MS and methylation-specific PCR are well suited for detecting low-abundance metabolites in various biological fluids and DNA in plasma and tissues for biomarker investigation. They offer great clinical promise for early disease diagnosis and therapeutic intervention. This dissertation broadly organized into two parts, part one talks about the application of …

Determination Of Hexavalent Chromium (Cr(Vi)) Concentrations Via Ion Chromatography And Uv-Vis Spectrophotometry In Samples Collected From Nacogdoches Wastewater Treatment Plant, East Texas (Usa), Kefa Karimu Onchoke, Salomey A. Sasu

Faculty Publications

The concentration of hexavalent chromium (Cr(VI)), a toxic environmental pollutant and carcinogen, was determined in samples collected from Nacogdoches Wastewater Treatment Plant (NWWTP) using ion chromatography and UV-visible spectrophotometry (IC, UV-Vis). On reaction with 1,5-diphenylcarbazide (DPC) Cr+6 forms a 1,5-diphenylcarbazide-Cr(VI) complex, which is then analyzed at 530nm and 540nm, respectively. Via ion chromatography Cr(VI) concentrations were in the range of 0.00190 ± 0.0020 and 0.0010 ± 0.0006ppm at the influent and effluent, respectively. With the use of standard addition wastewater samples were spiked with a 0.5ppm Cr(VI) standard of various amounts and subsequently analyzed with UV-Vis spectrophotometry. The spiked concentrations …