Analytical Chemistry Commons^™

Characterization Of L-Band Resonators And Relaxation Times Of Soₓ- Radicals At X-Band, Georgina Naa Odey Amassah

Electronic Theses and Dissertations

Electron Paramagnetic Resonance (EPR) analysis requires resonators optimized for specific experimental challenges. Volume resonators enclose samples, while surface coil resonators allow imaging of larger subjects. For in vivo studies, L-band frequencies are commonly used because they offer a good balance between signal-to-noise ratio (S/N) and the ability to penetrate tissue. Rapid Scan (RS) EPR at L-band frequencies was chosen for my studies of resonators because of this balance but presents a challenge for sensitivity.

The spatial position dependence of signal intensity was evaluated for selected paramagnetic samples using 10 mm and 30 mm surface coils. The 10 mm coil, with …

Electrochemical And Electrocatalytic Properties Of Screen-Printable Carbon Inks Featuring Pyridinic Nitrogen-Containing Polymeric Binder, Albert Sam Junior

Electronic Theses and Dissertations

Screen-printable conductive inks have been widely applied to prepare electrodes for electrochemical sensing. These inks generally consist of conductive metal or carbon particles, solvents, and polymeric binders. Low-cost, carbon-based, screen-printable conductive inks are especially popular. However, screen-printed carbon electrodes (SPCEs) must often be modified after they are printed to impart the necessary characteristics (e.g., sensitivity, selectivity, stability) for the desired application. For example, nitrogen-doping of SPCEs, especially in ways that introduce pyridinic or pyrrolic nitrogen species, can impart electrocatalytic properties towards reduction of O₂, H₂O₂, and CO₂. While our previous work done …

Visceral, Neural, And Immunotoxicity Of Per- And Polyfluoroalkyl Substances: A Mini Review, Pietro Martano, Samira Mahdi, Tong Zhou, Yasmin Barazandegan, Rebecca Iha, Hannah Do, Joel Burken, Paul Ki-Souk Nam, Qingbo Yang, Ruipu Mu

Chemistry Faculty Research & Creative Works

Per- and polyfluoroalkyl substances (PFASs) have gained significant attention due to their widespread distribution in the environment and potential adverse health effects. While ingestion, especially through contaminated drinking water, is considered the primary route of human exposure, recent research suggests that other pathways, such as inhalation and dermal absorption, also play a significant role. This review provides a concise overview of the toxicological impacts of both legacy and emerging PFASs, such as GenX and perfluoro butane sulfonic acid (PFBS), with a particular focus on their effects on the liver, kidneys, and immune and nervous systems, based on findings from recent …

Progress Towards Uranium Isotope Ratio Measurements Directly From Cotton Swipes With The Liquid Sampling – Atmospheric Pressure Glow Discharge (Ls-Apgd) Ionization Source, Joseph V. Goodwin

All Dissertations

The liquid sampling – atmospheric pressure glow discharge (LS-APGD) ionization source is a novel microplasma ionization source capable of ionizing a diverse set of both inorganic and organic chemical species including, ionic metal constituents as well as ligated metallic species, polyaromatic hydrocarbons (PAH), halogens, proteins, and even per/poly fluorinated alkyl substances (PFAS). The ability to generate ions from diverse chemical species, known as combined atomic and molecular (CAM) ionization, is not found with traditional ionization sources. In addition, the LS-APGD is capable of coupling with mass spectrometer platforms typically reserved for “organic” mass spectrometry, such as the high-resolution Orbitrap mass …

Advanced Analytical Biosensing For Cancer Detection And Neural Diagnostics Using Tapered Optical Fiber (Tof), Protonic, And High Throughput Microplate –Based Technologie, Bayan Hassan Alharbi

Chemistry & Biochemistry Theses & Dissertations

This dissertation investigates the development and application of advanced biosensing technologies to enhance early disease detection, neurological diagnostics, and bioactive compound evaluation. The research spans four key areas. First, it introduces tapered optical fiber (TOF)-based plasmonic biosensors for the non-invasive detection of prostate cancer, demonstrating high sensitivity and specificity compared to conventional diagnostic methods.

Second, it explores the use of fluorescent biosensors to test the Transmembrane Electrostatically Localized Proton (TELP) theory, shedding light on the role of localized protons in neuronal signaling and energy transfer. Third, the work presents a high-throughput, microplate-based biosensing platform for analyzing mitochondrial function under nanosecond …

Highly Contaminated Sediments From The Gowanus Canal (New York) Superfund Site: An Environmental Forensic Approach, Michael A. Kruge, Kevin K. Olsen, Eric A Stern, Maria Mastalerz, Albert Permanyer

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The 2.5 km long Gowanus Canal (Brooklyn, NY, USA) is a severely contaminated urban waterway dating from the mid-19th century, listed as a US Environmental Protection Agency (USEPA) Superfund site since 2010. Applying an environmental forensics approach to the extensive USEPA data set, we detect systematic variations in parent PAH ring number distributions in the canal sediments, as well as an extraordinary enrichment in organic carbon. We subjected a supplemental sample set to a more detailed analysis by quantitative pyrolysis-GC-MS, Rock-Eval pyrolysis, and organic petrology. With these sensitive methods, we can confirm the alkyl-PAH fingerprint of coal tar (a legacy …

Numerical Simulation Of The Pitting Corrosion Behavior Of Stainless Steel Bellows Influenced By Varying Liquid Film Thicknesses, Lu-Jun Ren, Guo-Min Li, Zhen-Xiao Zhu, Hai-Yan Xiong, Bing Li

Journal of Electrochemistry

To advance the understanding of the corrosion behavior of stainless steel bellows in marine atmospheric environments and enhance the precision of service life predictions, this study employs finite element simulations to investigate the pitting corrosion rates and pit morphologies of bellows peaks and troughs under varying electrolyte film thicknesses. The model incorporates localized electrochemical reactions, oxygen concentration, and homogeneous solution reactions. For improved computational accuracy, the fitted polarization curve data were directly applied as nonlinear boundary conditions on the electrode surface via interpolation functions. Simulation results reveal that the peak regions exhibit faster corrosion rates than the trough regions. With …

Ionic Liquid Enhanced Proton Transfer For Neutral Oxygen Evolution Reaction, Ming-Xing Chen, Nian Liu, Zi-He Dua, Jing Qi, Rui Cao

Journal of Electrochemistry

The development of highly active catalyst in pH-neutral media for oxygen evolution reaction (OER) is critical in the field of renewable energy storage and conversion. Nevertheless, the slow kinetics of proton-coupled electron transfer (PCET) hinders the overall OER efficiency. Herein, we report an ionic liquid (IL) modified CoSn(OH)₆ nanocubes (denoted as CoSn(OH)₆-IL), which could be prepared through a facile strategy. The modified IL would not change the structural characteristics of CoSn(OH)₆, but could effectively regulate the local proton activity near the active sites. The CoSn(OH)₆-IL exhibited higher intrinsic OER performances than the pristine …

Nanoporous Gold Nanoparticles And Model Membrane Systems Applied To The Study Of Lipopolysaccharide (Lps), Dhanbir Lingden

Dissertations

Lipopolysaccharide (LPS), a key structural component of Gram-negative bacteria, is a major trigger of sepsis and septic shock, the systemic inflammatory conditions responsible for millions of deaths annually. Even at concentrations as low as 1 ng/mL, LPS can activate the immune system and initiate inflammatory cascades. According to the Global Burden of Disease Study 2017, sepsis accounted for 48.9 million cases globally, with 11 million deaths, emphasizing the urgent need for improved diagnostic and therapeutic strategies.

Accurate and rapid detection of LPS is vital for early intervention and improved clinical outcomes. While traditional detection methods are still widely used, modern …

Signal And Noise Analysis In An Undergraduate Instrumental Analysis Laboratory, Ken Overway

Chemistry Faculty Scholarship

Understanding the difference between signal and noise in a measurement is fundamental to analytical chemists. The typical instruments found in an undergraduate chemistry department can be used to teach this concept, as well as signal averaging, by giving students hands-on experience with measurements and data processing. This work presents an undergraduate laboratory module (homework and experiment) that provides specific instructions for using gas chromatographs, fluorometers, a nuclear magnetic resonance spectrometer, an atomic absorption spectrophotometer, and an infrared spectrometer to collect replicate measurements and a framework for calculating the noise level, baseline, signal level, signal-to-noise ratio (SNR), and the signal thresholds …

Modified 2-Quinolinones For Photocatalysis: The Fluorescence Quantum Yield (Φf) Of Novel 2-Quinolinone Derivatives, Reggina Moreno Trevino, Graham Griffin

DePaul Discoveries

The photophysical properties of novel 2-quinolinone derivatives were examined to evaluate their potential as photocatalysts using fluorescence and UV-Vis absorbance spectroscopy. The fluorescence quantum yields were determined via the relative comparative method, using target absorbance values at a specific wavelength to prepare solutions and comparing these measurements to the reference molecule carbostyril-124. Molar absorptivity values were also calculated to assess the light absorption properties for each compound. Among the derivatives, PAV-3 presented with the highest molar absorptivity and fluorescence quantum yield values (ε= 15297.3 M-1 cm-1, ΦF= 17.1%), while PAV-5 showed the lowest (ε= 4796.2 M-1 cm-1, ΦF= 2.3%). The …

Electrochemistry Behind Pfas: Mechanistic And Analytical Approach For Sensing And Degradation Strategies, Jonathan Josue Calvillo Solis

Open Access Theses & Dissertations

Understanding the fundamental electrochemistry of perfluoroalkyl substances (PFAS) is key to developing effective water remediation and sensing strategies. This work explores the thermodynamics and kinetics of perfluorooctanoic acid (PFOA) electroreduction, focusing on C-F bond cleavage. These insights were applied to design a highly sensitive electrochemical sensor for detecting trace levels of PFOA in water. This dissertation focuses on the electrochemical investigation of the reduction reaction of PFOA in aqueous and organic media employing different electrode materials. This exploration allows to understand the defluorination reaction of PFAS to further propose potential strategies for water treatment and PFOA electrosensing. Through electrochemical, spectroscopical …

Quantifying Biomass Burning Impacts On Soil Nox Emissions And Reactive Nitrogen Cycling, Olivia Rae Steinbeck

Theses and Dissertations

Nitrogen oxides (NOx = NO + NO₂) are trace gases that play a critical role in the atmosphere by influencing air quality, oxidation chemistry, and the deposition of fixed nitrogen. Historically, NOx emissions have been primarily linked to anthropogenic sources such as fossil fuel combustion, industrial activities, and agriculture. However, as successful legislation has significantly reduced these emissions, the relative importance of natural NOx sources has become an increasing concern. Soil NOx emissions are of particular interest due to their strong temperature dependence and their connection to global climate change. Rising global temperatures are expected to accelerate soil NOx emissions …

Quinone-Mediated Extracellular Electron Transfer In Escherichia Coli During Glucose Oxidation Metabolism, Megan Danielle Whisonant

Theses and Dissertations

The growing global demand for energy, ongoing reliance on fossil fuels, and increasing water pollution from industrial and anthropogenic sources present significant environmental challenges. In response to these issues, renewable and sustainable energy sources offer substantial potential for reducing dependence on fossil fuels and ensuring access to clean water. Microbial electrochemical systems (MESs) have emerged as promising, eco-friendly solutions for energy-efficient wastewater treatment and bioremediation. A key challenge in MESs development is facilitating effective electron transfer between microorganisms and electrode surfaces. The first chapter of this thesis discusses the fundamentals of MES types, explains mechanisms of extracellular electron transfer, and …

Characterizing Dissolved Organic Matter Composition In A Southeastern United States Watershed, Gwendolyn Marcelette Hopper

Theses and Dissertations

Dissolved organic matter (DOM) has important roles in many biogeochemical cycles. DOM is primarily composed of dissolved organic carbon (DOC), nitrogen, and phosphorus, and the processing of DOM is important for nutrient regulation and carbon cycling. In the coastal plains of the southeastern United States, there are many rivers and streams known as “blackwaters” with exceptionally high concentrations of chromophoric dissolved organic matter (CDOM) leached from terrestrial soils, coinciding with a region experiencing some of the nation’s highest rates of development. As changes in land use and climate continue to occur, DOM composition from natural to anthropogenically impacted systems can …

Pm Irras Studies Of Organized Molecular Films At A Gold Electrode Surface, Zhang-Fei Su, Ai-Cheng Chen, Jacek Lipkowski

Journal of Electrochemistry

This feature article illustrates the potential of polarization modulation infrared reflection absorption spectroscopy (PM IRRAS) to provide molecular-level information about the structure, orientation and conformation of constituents of thin films at electrode surfaces. PM IRRAS relies on the surface selection rules stating that the p-polarized IR beam is enhanced, while the s-polarized beam is attenuated at the metal surface. The difference between p- and s-polarized beams eliminates the background of the solvent and provides IR spectra at a single electrode potential. In contrast, two other popular in situ IR spectroscopic techniques, namely, subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS) …

Redox-Active Monolayers On Ito Prepared By Post-Amidation And Direct Esterification And Their Spectroelectrochemical Characterization, Takamasa Sagara, Sae Nakai, Ryusuke Yofu, Shota Kojin

Journal of Electrochemistry

A redox-active monolayer on an optically transparent electrode constitutes a typical platform for spectroelectrochemical sensing. The necessity for its sophistication arises from the availability of multi-dimensional sensing signals. Simultaneous monitoring of the redox current and color change synchronized with the oxidation state change significantly enhances sensitivity and selectivity. This study aimed to elucidate the modification of an indium tin oxide (ITO) electrode with a viologen monolayer with an ordered orientation. Novel methods were developed to immobilize a viologen molecule bearing a carboxyl group to form assembled monolayers through a condensation reaction using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide with N-hydroxy-succinimide (EDC/NHS). In the two methods …

Chemical And Physical Characterization Of Verbenaceae Essential Oils Using Modern Analytical Methods And Chemometrics, Aleksandra N. Hilliard

Master's Theses

Essential oils have been used for generations to treat various health issues, including mitigating insomnia, reducing stress, inflammation, and preserving foods, to mention a few. Essential oils have complex chemistry, which defines the essence of the host plant. Recently, increased commercial uses of essential oils have prompted attention at the governmental level to monitor the chemical, physical, or biological activity of essential oils. This study is an attempt to add new information for consumers to the understanding of the composition of essential oils.

Modern analytical techniques including FTIR-ATR, GC-MS, LC-MS-MS, multivariate analysis statistics, and physio-chemical techniques (electrochemistry, DPPH, TRC, and …

Advances In And Applications Of Capillary Scale Liquid Chromatography, Samuel William Foster

Theses and Dissertations

Analytical-scale high performance liquid chromatography (HPLC) is one of the most widely used analytical techniques in the world. Efforts have been made to reduce the mobile phase consumption of HPLC by reducing the inner diameter (I.D.) of the column. By using capillary-scale columns (< 0.5 mm I.D.), separations can be performed with orders of magnitude less solvent consumption. This work describes advances made to capillary scale instrumentation as well as applications enabled by these advances. A compact capillary-scale LC was used for the analysis of numerous pharmaceutical and illicit drug compounds for point of need analysis. A miniaturized mass spectrometer was coupled to this instrument for on-line reaction monitoring within a standard chemical fume hood. Kinetic profiles of commercially available capillary columns were developed in order to provide guidance to others during column selection. The implementation of a column oven improved the analysis of large biopharmaceuticals. Several critical quality attributes of monoclonal antibodies including fragmentation, charge variants, and glycosylation profiles were able to be determined on the capillary scale. These results will help to make capillary-scale liquid chromatography a more viable solution for chromatographic analysis.

Characterizing Electrospray Performance Of Hydroxylammonium Nitrate (Han) And 2-Hydroxyethylhydrazinium Nitrate (Hehn) Ionic Liquids By Mass Spectrometry And Dynamics Simulations, Wenjing Zhou

Dissertations, Theses, and Capstone Projects

Dual-mode propulsion combines chemical and electric propulsion methods into a single compact system by sharing hardware and propellant for both modes, offering complementary advantages tailored to specific mission needs. A promising propellant candidate for dual-mode propulsion is a binary mixture of hydroxylammonium nitrate (HAN) and 2-hydroxyethylhydrazinium nitrate (HEHN) ionic liquids (ILs). Each of the two ILs was developed as a greener alternative to the traditional, yet toxic, hydrazine monopropellant used in chemical propulsion. Recently, their potentials in electrospray propulsion have garnered attention. This thesis focused on the investigation of reaction dynamics and kinetics of HAN, HEHN and their binary mixture …

Early-Stage Detection Of Copper Ion Release From Bronze Corrosion Using Uv/Vis Spectroscopy And Hydrogel Sensing, Hibah Khan

University Honors Theses

Detecting copper(I) (Cu⁺) release at early corrosion stages is important for preserving bronze heritage materials. This study investigated the use of neocuproine (NC), a Cu⁺-specific ligand, for simple and selective colorimetric detection of Cu⁺ in solution. NC reacts with Cu⁺ to form a Cu(NC)₂ complex, which produces a distinct orange-red color with peak absorbance at 455 nm. Solutions were prepared with varying concentrations of Cu⁺ generated by reducing Cu²⁺ with excess ascorbic acid. Ultraviolet/Visible (UV/Vis) spectroscopy was used to quantify absorbance changes. The absorbance at 455 nm increased linearly across the tested Cu⁺ concentration range (6.25–200 µM) with an R² …

Bio-Based Composites With Enhanced Mechanical Strength And Flame Retardancy, Riya Patel

Electronic Theses & Dissertations

Composites are versatile and useful in many fields, including aerospace, automotive, construction, and healthcare, due to their high mechanical strength. It is common practice to synthesize these materials using petroleum-based chemicals. Nonetheless, in the twenty-first century, scientists are more interested in using renewable resources to create composites. The greatest substitute for petroleum-based chemicals is vegetable oil. It has unsaturated double bonds that are modifiable chemically. In the present study, bio-polyol was synthesized using castor oil, an inedible vegetable oil. A ring-opening process was used to modify it and produce castor oil-based polyol. The synthesized castor oil-based polyol was characterized by …

Trade-Off Between Limonene & Geraniol-Based Reprocessable And Non-Reprocessable Epoxy Thermosets: Role Of Aliphatic Diamines In Polymer Networks Design, Priyankkumar Kanubhai Patel

Electronic Theses & Dissertations

The growing demand for sustainable materials, driven by environmental concerns and the rapid depletion of fossil fuels, has garnered significant attention in the fabrication of bio-based epoxy thermosets as renewable alternatives to petroleum-derived thermosetting polymers. The present study focuses on the synthesis and characterization of epoxy prepolymer resins derived from limonene and geraniol via a two-step process, followed by the fabrication of thermally cross-linked flexible epoxy thermoset films using various traditional aliphatic diamine curing agents, namely 1,2-ethylenediamine (EDA), 1,4-butylenediamine (BDA), and 1,6-hexamethylenediamine (HDA). Additionally, the incorporation of cystamine, a disulfide-containing diamine, enabled the formation of a covalent adaptable network through …

Structure Determination Of Mg2tihn And Mg3tihn (N=1-25) Clusters, Meagan Dobbs

Honors College Theses

Fossil fuels are a resource that is used in everyday life. A major problem with the reliance on fossil fuels lies in their major contributor to global warming. When fossil fuels are burned, they release greenhouse gases into the atmosphere and warm the Earth. In order to decrease the amount of greenhouse gases being emitted new fuel sources are being considered, and a leading candidate is hydrogen. This project looks at magnesium hydride clusters doped with a titanium atom. Specifically, the Mg₂TiH_n (n =1-25) and Mg₃TiH_n (n =1-25) clusters are considered. The …

Molecular Insights: Advances In Single Molecule And Single Particle Detection For Analysis Of Chemical, Physical, And Biological Phenomena, James Ethan Batey

Chemistry & Biochemistry Undergraduate Honors Theses

This thesis is focused on recent advancements made in the field of chemical imaging, optical microscopy, and recent developments that have improved spatial, temporal, or spectral resolution or have made certain techniques more accessible and cost effective for their wider adoption. This thesis is organized based on the systems of interest we studied with each new technique. Although, it is important to note that many of the methods here can be used with a multitude of systems even if not explicitly mentioned. The first chapter of this thesis will discuss the current state of chemical imaging, common terminology, and important …

Development Of Mixed O/S-Donor Imidazole Thione Ligands For Trivalent Lanthanide/Actinide Separations, Rhianna Wolsleger

All Dissertations

Separation of lanthanides and actinides is difficult due to their very similar size and charge. Increasing selectivity for actinides over lanthanides is possible by incorporating a softer, more polarizable donor atom into a chelating ligand, since the softer donor atom is capable of greater orbital overlap with the 5f orbitals of the actinides vs the 4f orbitals of the lanthanides. Sulfur-containing imidazole thione chelating ligands have not been investigated for this purpose but possess a resonance structure that puts significant negative charge on the sulfur, enabling it to form strong metal-sulfur bonds compared to other sulfur-containing ligands such as thioethers …

A Spectroscopic Survey Of Atmospheres Of Super-Earths, Luke Brust

Honors Theses

Recent research has made it possible to use spectroscopy to analyze the composition of the atmospheres of exoplanets, planets that orbit other stars. Most projects thus far have focused on the atmospheres of gas giants, as it is less challenging to observe them with available equipment. This project studies the atmospheres of four Super- Earths, planets that have a mass greater than the Earth but smaller than Neptune. This is accomplished by processing the raw spectroscopic data from the Hubble Space Telescope and modeling the atmosphere using the program 𝝉-Rex3. This survey found clear results from two of the selected …

Mechanistic Investigation Of Ring-Opening Polymerization Of Polycaprolactone Using Tin(Ii) Catalysts: Ligand Effects And Biomedical Applications, Eva-Larue M. Barber

Honors Scholar Theses

This research explores the mechanistic aspects of ring-opening polymerization (ROP) of ε-caprolactone (CL) to produce polycaprolactone (PCL), a biodegradable polymer widely used in biomedical applications. The study investigates how light exposure and catalyst concentration influence polymerization efficiency, using tin(II) 2-ethylhexanoate [Sn(Oct)₂] as the catalyst in a non-polar toluene solvent at 90 °C. Reactions were conducted under either ambient light or black light bulb (BLB) illumination, with monomer-to-catalyst ratios of 1:1 and 200:1.

Proton nuclear magnetic resonance (¹H NMR) spectroscopy was used to analyze conversion efficiency by tracking the disappearance of monomer signals and appearance of characteristic PCL peaks. Results revealed …

Kinetic Analysis Of Hydrolysis And Hydrothermal Conversion Of Methyl Cellulose To Dodecane, Joseph Olembo Were

Electronic Theses and Dissertations

Environmental pollution due to emission of greenhouse gases and increasing global energy demand are some of the concerns associated Analysis with the use of fossil fuels. These concerns have triggered the exploration of sustainable and efficient methods for renewable energy production. One such method is the conversion of cellulosic biomass to hydrocarbon fuels using hydrogen bronze metals. Cellulose is the most abundant biomass globally, and thus its utilization can lead to more sustainable energy production. Previous studies have reported the conversion of cellulose to hydrocarbons at high temperatures and hydrogen pressure. This work focuses on the conversion of methyl cellulose …

A Kinetic Analysis On Hydrolysis And Hydrothermal Conversion Of Cellulose To Dodecane, Joel Nyangoka Onyancha

Electronic Theses and Dissertations

Cellulose, the most abundant biomass on Earth, offers a promising pathway for alternative energy through conversion into alkane hydrocarbons. Traditional methods rely on high temperatures and high-pressure hydrogen, often derived from petroleum. In this study, we investigated the conversion of Microcrystalline Cellulose using hydrogen metal oxides (bronzes) under milder conditions. Following ASTM E3417-24 hydrolysis protocols, we employed hydrogen bronzes with toluene for product extraction. This approach enabled conversion at lower temperatures without pressurized hydrogen. Products were analyzed using Gas Chromatography Mass Spectrometer for identification and Gas Chromatography Flame Ionization Detector for quantification. Our findings revealed the formation of a possible …