Analytical Chemistry Commons^™

The Extraction And Chemical Characterization Of The Avian Pigments Turacin And Turacoverdin, Sarah R. Bekkali

Honors Scholar Theses

Bird coloration is a trait that extends beyond mere aesthetics as it has an extensive range of biological significance. Plumage patterns and hues can influence camouflage, mate choice, social dominance, and physiological performance. Bird fitness, their ability to survive and reproduce, is greatly dependent on color. Melanins, carotenoids, and pterins are well-studied pigment systems that are commonly found across many avian species’. Alternatively, porphyrin-based pigments are rare and less-studied as they only found in turacos a sub-Saharan African bird belonging to the family Musophagidae. This thesis focuses on two pigments of interest: turacin, the deep crimson-red pigment found in …

The Influence Of Fermentation Duration And Secondary Fermentation Conditions On The Bioactive Compound Profile Of Kombucha, Jordan Vereen

Honors Theses

Kombucha is a fermented sweet tea produced using a symbiotic culture of bacteria and yeast (SCOBY) and has gained widespread popularity due to its proposed health benefits. Kombucha has been studied to understand these advantages in cardiovascular support, improved metabolism, increased antioxidant effects, enhanced antimicrobial properties, and even potentially slowing the progression of certain diseases. Despite its increasing popularity, the way in which the specific bioactive compounds responsible for these effects and the fermentation conditions that influence their production remain unclear. The present study, conducted in collaboration with Dr. Budner, focuses on quantifying bioactive compounds in kombucha to better understand …

Tissue-Specific Heavy Metal Accumulation And Sediment–Mangrove Dynamics In Port Everglades, Florida, Dimitrios Giarikos, Amy Hirons, Jason Gershman, Sophie Welch

SECLER Data

Coastal wetlands near industrialized waterways face increasing heavy metal contamination, yet the role of mangroves as biogeochemical buffers remains poorly understood. This study quantified 16 heavy metals in sediments and red mangrove (Rhizophora mangle) tissues (roots, branches, and leaves) across four sites near Port Everglades, Florida, examining tissue-specific partitioning, contamination patterns, and sediment-to-plant transfer. The South Turning Basin (STB) was the principal contamination hotspot, with geometric mean (GM) concentrations of arsenic (As; 27.8 µg/g) and zinc (Zn; 203 µg/g) exceeding threshold effect levels, while Cu exceeded its probable effect level (PEL; 193 µg/g). Mercury (Hg) exceeded its PEL …

Chemometric Analysis Of Dissolved Organic Matter Using Fluorescence, Dani Fellner, Ken Overway

Honors Projects

Univariate spectroscopic techniques have been utilized to measure dissolved organic matter (DOM), but challenges arise in the separation and characterization due to similarities in chemical structures and spectral overlap. Multivariate techniques utilize a combination of known analytes with their unique excitation and emission spectra from fluorescence measurements to quantify amount of each analyte present in the mixture using parallel factor analysis. Tryptophan, tyrosine, and phenylalanine are common amino acids found in environmental samples and can be quantified due to their intrinsic fluorescence qualities. These amino acids can be utilized to estimate the amount of DOM in a sample since proteins …

Limit Of Detection Variations In Polyphenol Mixtures Using Parafac-Feem Spectroscopy, Ken Overway, Brockton Zorn

Honors Projects

Polyphenols are chemical compounds commonly found in food products like olive oil and red wine. Research suggests that their presence in such foods conveys positive cardiovascular and cognitive health benefits. This group of compounds is often difficult to quantify in such samples due to an overlap in the chemical signals and the presence of interferences, such as coloring, found naturally in the food. Use of 3D Fluorescence Excitation Emission Matrix (EEM) measurements combined with pH sensitivity could establish a method in which polyphenols are identified more easily in mixtures. Binary and ternary mixtures of polyphenols were analyzed without the additional …

High Throughput Phenomics Pipeline For Pulse Crop Nutritional Breeding, Amod Udayanga Madurapperumage

All Dissertations

Dry pea (Pisum sativum L.), lentil (Lens culinaris Medik.), and chickpea (Cicer arietinum L.) are major pulse crops valued for their high nutritional composition and importance to global food systems. Pulses are rich in carbohydrates, protein, and essential minerals, making them ideal whole foods and critical contributors to food and nutrition security. Due to these advantages, pulse breeding programs are increasingly focusing on enhancing nutritional traits, such as protein quality, amino acid balance, and micronutrient density, through the process of biofortification. However, improvement of agronomic traits remains equally essential. Characteristics such as plant height, standability, stress tolerance, …

Urea-Based Boronium Salts As Antimicrobial Agents, Gabriel Allen Merchant

Honors Theses

Quaternary ammonium compounds (QACs) are widely used in disinfectants due to their ability to inhibit the growth of and eliminate microbes. The potency, broad-spectrum activity, and low cost of QACs have made them a cornerstone of modem hygiene. In recent years, QACs have garnered many health and safety concerns due to their overuse and subsequent accumulation in the environment. The increased use of QACs has further led to an increase in antimicrobial-resistant bacteria, making the synthesis of novel antibacterial compounds vital to combat this growing threat. Recent advances in boronium salts offer a unique alternative to address these adverse effects. …

Stability Of Paraffin-Insulated Nitrogen-Doped Carbon Fiber Ultramicroelectrodes, Maxwell H. Kwakwah

Electronic Theses and Dissertations

Nitrogen-doped carbon materials can facilitate the reduction oxygen-oxygen bonds, a key step in electroreduction of both O₂ (an important reaction in energy applications) and H₂O₂ (an important reaction in sensing and biosensing). Our lab previously demonstrated that thermal decomposition of urea in the presence of carbon fiber (CF) results in an N-doped carbon material that exhibits good electrocatalytic properties for H₂O₂ reduction. However, previous methods of insulating single N-doped CF via laser heating of borosilicate capillaries and epoxy to prepare ultramicroelectrodes (UMEs) seemed to adversely affect surface nitrogen contents and electrocatalytic properties. More recent work that utilized paraffin to …

Multiplexing Reductive Alkylation Of Peptides For Quantitative Proteomics, Kevin C. Souza

Honors Scholar Theses

Reductive alkylation is a robust and commonly used labeling technique for quantifying proteins and peptides in complex samples using mass spectrometry. This technique involves the attachment of alkyl groups to an amino group at the N-terminus and lysine residues of a peptide, causing a mass shift that is detectable using mass spectrometry. This work aims to explore the application of reductive alkyl labeling in multiplexed quantitative proteomics. The first part of the study investigates the effectiveness of the labeling of peptides using a variety of aldehydes via reductive alkylation. The aldehydes were chosen, such that they provided various degrees of …

Taking A Deeper Look: Attributing Tonal Values Of Photolumens To Their Emulsions Using Scanning Electron Microscopy, Anna M. Moore

All Theses

This thesis examines whether tonal variation in photolumens made with historic silver gelatin photographic papers can be linked to differences in elemental composition. Photolumens are cameraless photographic images created by placing objects directly on light-sensitive paper and exposing them to ultraviolet light. Because expired and historic darkroom papers often produce unpredictable colors and tones, this study asks whether visually defined tonal groups also show measurable chemical differences.

Twenty historic paper samples were exposed, documented, and sorted into five tonal groups based on visible image characteristics. Each sample was then analyzed using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) …

Energetic Eutectics: An Experimental And Computational Investigation On Explosive Deep Eutectic Solvents, Connor J. Parker

All Theses

This study reports on the incorporation an extreme gradient boosting (XGBoost) machine learning strategy tailored to identifying potential high-energy, insensitive explosive deep eutectic solvents. 1,1-diamino-2,2-dinitroethylene (FOX-7) was investigated as the explosive of interest in our eutectic modeling. The resulting predictions highlighted a wide range of binary compositions demonstrating significant depression from the FOX-7 melting temperature with >70% probabilities of formation. Subsequent computational investigation into select mixtures provided underlying stabilization energies and optimized mixture geometries, which were then assessed experimentally with near simulant compounds oxalyldihydrazide and 1-methyl-3- nitroguanidine replacing FOX-7.

Experimental results with these chosen simulants did not demonstrate classical eutectic …

Investigation Of Curing And Degradation Mechanisms In Lead White Oil Paint Systems: Impact Of Methyl Linoleate On Paint Matrix Formation And Solvent Extractability, Andrea Serrano Trujillo

Theses, Dissertations and Culminating Projects

Oil-based paints composed of drying oils and lead-containing pigments undergo complex chemical transformations during curing that influence long-term stability and degradation. Despite centuries of use, the molecular mechanisms governing oxidative polymerization and additive incorporation in lead white oil paint systems remain incompletely understood. This study investigates the role of methyl linoleate, a monoester analog of linoleic acid, in the curing and degradation pathways of lead carbonate and linseed oil paint films. A deep focus was placed on determining whether methyl linoleate becomes chemically integrated into the developing polymeric network or remains as an extractable and unbound component, as this distinction …

Degradation And Metabolic Analysis Of Synthesized Quorum-Sensing Signals By The Model Eukaryote Chlamydomonas Reinhardtii, Adam Josef Bach

Theses and Dissertations

Bacterial organisms can “talk” with one another on a colony-wide scale using a communication system known as quorum-sensing (QS) via chemical signals. These signals are produced at a basal rate throughout the life of the bacteria and are classified as autoinducers, which diffuse across the cell membrane. Once the critical concentration is reached, they begin to diffuse back into the cell and initiate a phenotypic change. As these signals exist outside the membrane of their producer, they are also accessible to other organisms. It has already been noted that some plant species uptake these compounds through their roots and break …

Nanoscale Electrochemical Measurements: Theory, Instrumentation, And Operation, Kamsy Lerae Anderson

Graduate Theses and Dissertations

Electrochemical processes underpin many modern technologies (e.g., batteries, fuel cells, and corrosion protection systems), and because these processes are often controlled by interactions that occur at the nanoscale, gaining insight into nanoscale electrochemical behavior is essential to advancing these technologies. Nanoscale electrochemical imaging probes measure electrochemical activity with nanoscale spatial resolution and have enabled researchers to gain new insights into diverse experimental systems. However, limitations remain, including a lack of methods for direct quantitative interpretation, the influence of atmospheric conditions on experimental reproducibility and stability, and a knowledge barrier resulting from limited accessible resources, all of which continue to restrict …

Advancement In Electrochemical Generation-Collection: Snapshot Redox Cycling Voltammetry For Rapid Analysis At Chip-Based, Individually Addressable Microband Electrode Arrays, Blake Aleck Sterling

Graduate Theses and Dissertations

Snapshot redox cycling voltammetry (Snapshot RCV) is introduced as a rapid electrochemical technique that reconstructs the current-potential profile of a redox active species using a microband electrode array. By simultaneously biasing individual generator electrodes alternating in the array to different voltages across the analyte’s potential range while individually holding collector electrodes at a reversing potential, “spatial” voltammetry is achieved in as little as 1 s with the temporal speed of chronoamperometry, rapidly capturing the steady-state redox cycling (RC) profiles. During RC (a mode of generation-collection), the analyte is oxidized (or reduced) at generator electrodes and converted back at neighboring collector …

Analysis Of The Flavonoid Composition Of Honey Using High-Performance Liquid Chromatography, Bryce Phillips

Honors Theses

Honey is a naturally occurring substance that has a complex composition including compounds such as flavonoids, that contribute to potential health benefits. Quantitative analysis of flavonoids in honey can be challenging due to their similar structural characteristics, matrix effects, and chromatographic peak separation issues. This study aimed to establish calibration curves for five flavonoids–kaempferol, luteolin, chrysin, myricetin, and quercetin– to estimate their concentrations in five honey samples from varying geographic origins. Liquid-liquid extraction was used to isolate the flavonoids from honey. High Performance Liquid Chromatography was utilized to establish calibration curves and analyze honey samples. The calibration curves assembled demonstrated …

Laser Ablation-Atomic Absorption Spectroscopy Of Yttrium Plasma, Dawn Gipson

Create@State

Laser ablation is a widely used sampling method for elemental chemical analysis. Laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively-coupled mass spectrometry (LA-ICP-MS) are the two most common implementations. Application of these techniques is found throughout the sciences, including analysis in archaeological settings, geology, and medical analysis of hard tissue such as teeth or bone. Many applications benefit from the microdestructive nature of the technique. However, the relationship between the laser-ablation crater and the analytical signal is poorly understood. Laser ablation-atomic absorption spectroscopy (LA-AAS) is used in our laboratory to determine the mass of material incorporated into the plasmas in …

Designing Surface-Induced Entatic States In Copper Complexes For Tunable Reactivity, Rachel Kiser

Senior Theses

Copper catalysts play an important role in electrocatalytic oxidation reactions due to their redox flexibility and relative abundance compared to noble metal catalysts. In biological systems, copper metalloenzymes often achieve enhanced reactivity through an entatic state. Entasis is described as an active site or metal center being constrained to a geometric and electronic state, minimizing primary sphere reorganization energy and achieving higher rates of electron transfer.  This study investigates whether entasis can be achieved in synthetic molecular catalysts by immobilizing Cu(I) complexes onto metal oxide surfaces. Two Cu(I) complexes bearing carboxylate-functionalized ligands were examined both in homogeneous solution and when …

Radicals Transforming Organic Matter: Implications For Non-Pyrogenic Black Carbon And Nitrogen Formation, Molecular Dynamics In Tropical Soils, And Lignin Valorization, João Vitor Dos Santos

Chemistry & Biochemistry Theses & Dissertations

Radicals drive the transformation of organic matter in natural and engineered systems, altering its structure, reactivity, and stability. Condensed aromatic carbon (ConAC) and condensed aromatic nitrogen (ConAN) are among the most persistent forms of organic matter in soils and are traditionally interpreted as products of biomass burning. This dissertation challenges the long-standing assumption that these materials are exclusively pyrogenic, showing that iron-mediated radical chemistry can generate condensed aromatic structures under ambient conditions.

Chapters II and III show that Fenton-like radical oxidation of lignin-rich biomass produces condensed aromatic structures compositionally similar to pyrogenic black carbon and black nitrogen when assessed with …

Anthrone-Based Dummy Molecularly Imprinted Polymer For The Selective Detection Of Fluorene And Phenanthrene In Simulated River Water, Aria Pinandita, Nurrahmi Handayani, Muhammad Iqbal, Untung Triadhi, Rusnadi Rusnadi, Samitha Dewi Djajanti, Muhammad Bachri Amran, Muhammad Ali Zulfikar

Makara Journal of Science

A dummy-template molecularly imprinted polymer (DMIP) was synthesized via precipitation polymerization using anthrone as a template analog for the selective analysis of low-molecular-weight polycyclic aromatic hydrocarbons (PAHs), specifically fluorene and phenanthrene. Styrene, benzoyl peroxide, and ethylene glycol dimethacrylate were employed as the functional monomer, radical initiator, and crosslinking agent, respectively. The synthesized polymers were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and particle size analysis. The imprinting factors were 1.16 and 1.09 for fluorene and phenanthrene, respectively, indicating enhanced affinity of the imprinted sites. High-performance liquid chromatography analysis following DMIP-based solid-phase extraction yielded recoveries of 91.49% ± 3.87% for …