Analytical Chemistry Commons^™

Elastic Properties Of 2d Ti3c2tx Mxene Monolayers And Bilayers, Alexey Lipatov, Haidong Lu, Mohamed H. Alhabeb, Babak Anasori, Alexei Gruverman, Yury Gogotsi, Alexander Sinitskii

Department of Chemistry: Faculty Publications

Two-dimensional (2D) transition metal carbides and nitrides, known as MXenes, are a large class of materials that are finding numerous applications ranging from energy storage and electromagnetic interference shielding to water purification and antibacterial coatings. Yet, despite the fact thatmore than 20 different MXenes have been synthesized, the mechanical properties of a MXene monolayer have not been experimentally studied. We measured the elastic properties of monolayers and bilayers of the most important MXene material to date, Ti₃C₂T_x (T_x stands for surface termination).We developed amethod for preparingwell-strainedmembranes of Ti₃C₂T_x monolayers …

Environmental Forensics Study Of Crude Oil And Petroleum Product Spills In Coastal And Oilfield Settings: Combined Insights From Conventional Gc-Ms, Thermodesorption-Gc-Ms And Pyrolysis-Gc-Ms, Michael A. Kruge, José Luis Gallego, Azucena Lara-Gonzalo, Noemi Esquinas

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

A representative set of five oil spill samples from four different regions displayed different product characteristics and different levels of weathering. Three of them were taken along shorelines affected by marine oil spill events, viz., Aboño and Prestige (Spain) and Deepwater Horizon (USA) and the other two were taken at inland oil spill sites (Angola and Kuwait). A multi-faceted environmental forensics approach revealed key molecular features. In addition to the conventional GC/MS analysis of saturated and aromatic fractions, the polar fractions also were analyzed, revealing a complex series of linear alkanones in those oil samples particularly enriched in aliphatics. Thermodesorption-GC-MS …

Oil Dries: A New Absorbent Material For Collection Of Ignitable Liquids From Semi-Porous Material, Jessica Sosa

Online Theses and Dissertations

Extraction of an ignitable liquid sample from a semi-porous surface such as concrete is especially difficult. For this purpose, two different solid oil dry absorbent materials, Instazorb and MAXXAbsorb, were researched for use of collection of ignitable liquid samples at a fire scene. These oil dries were spiked with different ignitable liquids (Coleman fuel, gasoline, kerosene, and diesel). Isolation of the ignitable liquid from the oil dry absorbent was accomplished by passive headspace isolation. Data was obtained by gas chromatography coupled with flame ionization detection (GC-FID) and gas chromatography coupled with mass spectrometry (GC-MS). Chromatograms obtained from both oil dries …

Development Of Multi-Class Analytical Methods For Agrochemical Contaminants, Sarah Tuck

Theses

In this project, cost-effective multi-class analytical methods were developed to detect a range of antiparasitic, feed additive and pesticide substances in foodstuffs of animal origin. These substances have the potential to enter the food chain through their occurrence as residues either through the animals themselves or other routes e.g. contamination. To ensure the continued safety of food destined for human consumption regulatory control limits have been established for permitted levels of these residues in foods of animal origin. Despite these controls the continued monitoring of foodstuffs is necessary to ensure these limits are not breached and that substances are not …

Synthesis, Characterization And Molecular Dynamic Simulations Of Aqueous Choline Chloride Deep Eutectic Solvents, Sampson Asare

Electronic Theses and Dissertations

Various forms of deep eutectic solvents have been synthesized with advantages of 100% atom economy, low vapor pressure, ease of preparation, cost efficiency, low toxicity, and tunability. Though several DESs have been synthesized and characterized, including binary and ternary solvents, none of the binary DESs have been formulated with water as the sole hydrogen bond donor(HBD). This is due to a couple of opinions. First, water is disruptive to the eutectic bond in tertiary DES. Secondly, the ubiquity and concentration of water even in natural systems have led to the assertion that a solution rather than a eutectic solvent will …

Development Of A High Performance Liquid Chromatography Method For The Analysis Of Next-Generation Cyanide Antidote, 3-Mercaptopyruvate, In Plasma, Elaf Alzhrani

Electronic Theses and Dissertations

Although the current FDA approved cyanide antidotes (i.e., sodium nitrite, sodium thiosulfate, and hydoxocoboalamine) are effective for treating cyanide poisoning, each individual antidote has major limitations, including large effective dosage, delayed onset of action, or dependence on enzymes generally confined to specific organs. To overcome these current limitations, next-generation cyanide antidotes are being investigated, including 3-mercaptopyruvate (3-MP). Analytical methods capable of detecting 3-MP from plasma are essential for the development of 3-MP as a nextgeneration cyanide antidote. Although 3-MP has been analyzed by LC-MS-MS, this instrument is not widely available. Therefore, a high performance liquid chromatography (HPLC) method with fluorescence …

Exploring New Synthetic Strategies By Using Novel Manganese Carboxylate Complexes Along With Two Alkoxide Based Ligands, 2-(Hydroxymethyl)-Pyridine And 4,5-Bis(Hydroxymethyl)-2-Methylpyridin-3-Ol In The Area Of Polynuclear Coordination Chemistry, Michael A. Reagan

College of Graduate Studies: Theses & Dissertations

Manganese carboxylate complexes have been well studied in the past, due to their relevance in bioinorganic chemistry and as well as their behavior as nanoscale magnetic materials that is called single-molecule magnets (SMMs). SMMs are special class of magnetic materials in which magnetism is intrinsic to the molecule. Polynuclear manganese clusters often possess high spin ground states as well as large and negative magnetoanisotropy, a combination which leads to an energy barrier for the reversal of the magnetization direction. The paramagnetic nature of manganese at its common oxidation states with an ample number of unpaired electrons often leads to high-nuclearity …

Biosensing And Catalysis Applications Of Nanoporous Gold (Npg) And Platinum-Speckled Nanoporous Gold (Npg-Pt) Electrodes, Christopher J. Freeman

Theses and Dissertations

The importance of porous materials has risen substantially in the last few decades due to their ability to reduce the size and cost of bioanalytical devices and fuel cells. First, this work aims to describe the fabrication of nanoporous gold (NPG) electrodes that are resistant to electrode passivation due to fibrinogen biofouling in redox solutions. The effect on potentiometric and voltammetric experiments was seen as a deviation from ideal behavior on planar gold electrodes, whereas NPG electrodes were consistently behaving in a Nernstian fashion at low concentrations of ferri-ferrocyanide (£100 mM). An improvement in electrode behavior on NPG electrodes versus …

Fast Isotope Ratio Mass Spectrometry (Firms): A Tandem Mass Spectrometry Technique For The Rapid And Semi-Comprehensive Evaluation Of Isotope Ratios, Fredrick Ochieng

Electronic Theses and Dissertations

Isotope ratios (IRs) are a measure of the variation in abundance of light isotopes versus heavy isotopes of an element, e.g. ¹H/²H,¹²C/¹³C, and ¹⁴N/¹⁵N. Because IRs change as a molecule undergoes certain chemical and physical processes, they represent unique fingerprints that can be used to trace the source of a chemical compound. Current techniques for determination of IRs each have major limitations, such as loss of structural information, vulnerability to contamination, high cost, large sample size requirements, low precision, limited applicability, and lengthy analysis. Fast Isotope Ratio Mass Spectrometry (FIRMS) …

Technology Development For Detection Of Circulating Disease Biomarkers From Liquid Biopsies Using Multifunctional Nanomaterials, Mustafa Balcioglu

Legacy Theses & Dissertations (2009 - 2024)

Despite the advance health care, devastating health conditions such as cancer and infectious diseases that affect populations worldwide are too often not diagnosed until morbid symptoms become apparent in the late phase. Obtaining an early and accurate diagnosis that reveal a hidden lethal threat before the disease becomes complicated may dramatically reduce the severity of its impact on the patient’s life and increase the probability of survival. For example, in the case of ovarian cancer, which is the fifth most common malignancy and the fifth leading cause of cancer mortality in women in the US, the 5-year relative survival is …

A Consideration Of Ancient Residues And Their Analysis, Jennifer A. Cardinal

Legacy Theses & Dissertations (2009 - 2024)

Identification of specific use(s) of ancient pottery vessels through empirical verification is currently very limited for archaeological investigations. Although we can postulate a range of purposes or functions for certain vessels, empirical confirmation of actual use has been determined only for a minuscule portion of the available vessels. This thesis will provide a broad review of organic analyses as applied to foodstuff residues left on ancient artifacts as well as discuss several considerations for such analysis that are unique to their application to archaeological specimens.

Application Of Group I Metal Adduction To The Separation Of Steroids By Traveling Wave Ion Mobility Spectrometry, Alana L. Rister, Tiana L. Martin, Eric D. Dodds

Department of Chemistry: Faculty Publications

Steroids represent an interesting class of small biomolecules due to their use as biomarkers and their status as scheduled drugs. Although the analysis of steroids is complicated by the potential for many isomers, ion mobility spectrometry (IMS) has previously shown promise for the rapid separation of steroid isomers. This work is aimed at the further development of IMS separation for the analysis of steroids. Here, traveling wave ion mobility spectrometry (TWIMS) was applied to the study of group I metal adducted steroids and their corresponding multimers for five sets of isomers. Each set of isomers had a minimum of one …

Magnetic Assembly Of Soft Robots With Hard Components, Sen Wai Kwok, Stephen A. Morin, Bobak Mosadegh, Ju-Hee So, Robert F. Shepherd, George M. Whitesides

Department of Chemistry: Faculty Publications

Reconfigurable soft robotic actuators with hard components are described. Magnetic attraction is used to couple flexible molded bodies capable of actuation upon pressurization with other flexible molded bodies and/or with hard components (e.g., frames and connectors) to form a seal for fluidic communication and cooperative actuation. Pneumatic decoupling chambers built into the hard components to decouple the hard components from the magnetically-coupled soft molded bodies are described. The use of magnetic self- alignment coupling and pneumatic de-coupling allows for the remote assembly and disassembly of complex structures involving hard and soft components. The magnetic coupling allows for rapid, reversible reconfiguration …

Flexible Thin Robotic Actuators, Aaron D. Mazzeo, Stephen A. Morin, Robert F. Shepherd, George M. Whitesides, William B. Kalb

Department of Chemistry: Faculty Publications

Some embodiments of the disclosed subject matter includes a laminated robotic actuator. The laminated robotic actuator includes a strain-limiting layer comprising a flexible, non extensible material in the form of a sheet or thin film, a flexible inflatable layer in the form of a thin film or sheet in facing relationship with the strain-limiting layer, wherein the inflatable layer is selectively adhered to the strain-limiting layer, and wherein a portion of an un-adhered region between the strain-limiting layer and the inflatable layer defines a pressurizable channel, and at least one fluid inlet in fluid communication with the pressurizable channel. The …

Mechanistic Studies Of Proton-Coupled Electron Transfer Reactions Involving Antioxidants, Kejie Meng

Theses and Dissertations

The objective of the research was to investigate proton-coupled electron transfer (PCET) reactions involving antioxidants to gain insight into the detailed mechanisms of glutathione (GSH), Trolox, and α-tocopherol (α-TOH). PCET reactions are complex redox reactions that transfer electrons and protons sequentially or in concert. These reactions are ubiquitous in natural or artificial processes that produce electrochemical energy that is extractable as electricity or as chemical fuels of high energy content. Examples of processes based on PCET are photosynthesis, respiration, nitrogen fixation, carbon dioxide reduction, redox fuel cells, and artificial photosynthesis. Antioxidants were selected as a PCET model to understand the …

Synthesis And Kinetic Activity Analysis Of Substituted Pyrazole, Pyrazoline, And Pyrazolidine Alcohol Dehydrogenase Inhibitors, Meagan E. Hackey

Chemistry Theses

Alcohol dehydrogenase inhibitors may be employed for the treatment of parasitic infection in humans. A series of substituted pyrazoline derivatives were synthesized to elucidate the pharmacophore for the inhibition of ADH. Targeted structure modification was used to alter the electronic and steric interactions associated with the enzyme active site. This study identified several effective N-aryl-carboxamide derivatives with horse liver ADH inhibition, comparable to that of 4-methylpyrazole, a known ADH inhibitor. The identification of pharmacophoric regions will allow for the methodological modification of these compounds to improve enzyme affinity and targeted inhibition. Future research may include additional solubility, toxicity and …

Integrating Microscale Enzyme And Lectin Reactions Using Nanogel Assisted Capillary Electrophoresis, Srikanth Gattu

Graduate Theses, Dissertations, and Problem Reports (ETD)

Protein glycosylation is one of the most prevalent post-translational modifications which plays an important role in determining the structure, stability, and function of proteins. Changes in glycosylation patterns are a hallmark of cancer and other diseases. Characterizing glycosylation is difficult because these structures vary in their linkage and monomer sequence, which gives rise to vast microheterogenity that could affect the function of the molecule. A novel method using capillary gel electrophoresis by integrating microscale enzymes and lectin reactions in the capillary was developed to verify glycan structure by analyzing monosaccharides. Capillary electrophoresis (CE) improves upon conventional methods of glycan structure …

Development And Characterization Of A Paper Based Analytical Device For Heparin Quantification, Carolanne Norris

Undergraduate Honors Thesis Projects

Paper-based analytical devices (PAD) have gained popularity in the past ten to fifteen years due to many favorable mechanical properties.1 They have largely been used to analyze small ionic species, such as Na+ and Li+, but little research has been done on their capability of to analyze large polyionic species, for instance the highly sulfonated polysaccharide heparin.2,3 This study explores adaptation of a traditional optode design to a low cost PAD that employs a smartphone as a detector. Throughout the study variables, such as membrane composition, pH, volume of solution, time, addition of a polymer, use of different cell phone …

Characterization Of Fragrant Chemical Components Of Essential Oils Of Lavender, Violet, And Bergamot By Gas Chromatography-Mass Spectrometry, Akeem Babalola Opakunle

Chemistry Theses

The characterization of fragrant chemical composition of commercial samples of lavender, violet and bergamot essential oil were analyzed using gas chromatography-mass spectrometry (GC-MS) techniques. The analysis led to the characterization of a total of 28 compounds for lavender oil, 17 compounds for violet oil, and 11 compounds for bergamot oil. The commercial sample of lavender essential oil has shown to be abundant in linalool, (21.40%), linalyl acetate (18.96%), trans-β- ocimene (7.41%), endo-borneol (6.53%), β-ocimene (6.43%), geranyl acetate (6.15%), β-myrcene (5.88%), terpinen-4-ol (5.70%) and cis-β-farnesene (4.40%). For commercial sample of violet essential oil, the major components in abundant were α-longipinene (37.35%), …

Determination Of The Oxidative Capacity Of Soot Toward Gsh And Characterization Of Soot Physicochemical Properties, Kaylee Troth

All Master's Theses

Fine atmospheric particulate matter (PM_2.5) emitted during the combustion of fossil and biomass fuels is known to adversely affect human health. While the underlying mechanisms are thought to be driven by the generation of reactive oxygen species (ROS), specific particle characteristics responsible for this detrimental effect are not well understood. In this research, the quantitative determination of the biologically relevant antioxidant, glutathione (GSH), was optimized for use as an indicator of oxidative stress to shed light on relevant particle characteristics. This was accomplished via fluorescent spectroscopy for GSH determination by way of reaction with o-phthalaldehyde (OPA), a …

Characterization Of Coacervate Systems Using Redox Sensitive Dyes, Caleb Kaiser

All Master's Theses

Coacervates are systems that spontaneously form when two oppositely charged polyelectrolytes are mixed in a concentrated salt solution. When coacervates form, a biphasic equilibrium occurs in the sample with two phases present in the solution. The two phases are described as the dense phase and the lean phase, named after the amount of polyelectrolyte material in each phase. Coacervates have been topics of interest to researchers in a variety of fields including biomedical applications, drug delivery devices, and more. This thesis worked towards the characterization of coacervate systems on the molecular level by investigating the interaction of the polyelectrolytes and …

Stability Of Bimetallic Clusters In Protein Model Systems, Sean Hartnett

Master’s Theses

Heterobimetallic cofactors are commonly found in proteins and allow them to perform unique chemical processes that would otherwise not be possible. The interactions between these metals allow the protein to accomplish difficult chemical transformations. Previously, the thermodynamic stability of a Fe^II /Mn^II cluster in the dinucleating ligand F-HXTA (5-fluoro-2-hydroxy-1,3-xylene-α,α′-diamine-N,N,N′,N′-tetraacetic acid) has been investigated in our lab as a model of cluster assembly in the proteins ribonucleotide reductase (RNR) and R2-like ligand binding oxidases (R2lox). By measuring equilibrium concentrations of F-HXTA complexes via ¹⁹F-NMR, it was found that the equilibrium for metal exchange between the homobimetallic …

Integrated Immunoassays On Paper/Polymer Hybrid Microfluidic Devices For Low-Cost Detection Of Disease Biomarkers, Sanjay Sharma Timilsina

Open Access Theses & Dissertations

Infectious diseases and cancers have been the major cause of global death and disability causing a significant impact on global health and economies. Enzyme-linked immunosorbent assay (ELISA) is one of the most widely used laboratory diagnostic methods for infectious diseases and cancer. ELISA detects proteins based on their binding to immobilized antibodies or antigen. Even though most ELISAs performed today in 96-well plates are well suited for high throughput assays, performing ELISA in low-resource settings is limited by several factors, such as long incubation time, large volumes of precious reagents, and well-equipped laboratories. Herein, we have developed multiple simple, miniaturized …

Interfacial Corrosion Of Copper And The Formation Of Copper Hydroxychloride, Mary Teague, Shengxi Li, Hongbo Cong

Williams Honors College, Honors Research Projects

Electrical circuitry is an industry, among many others, heavily using the element of copper. Ensuring the mechanical integrity of Cu is crucial, especially in salt environments, for the multifaceted composition of circuits. 4N NaCl solution (equilibrium concentration in ~84% RH) simulated this three-phase system. Rectangular Cu samples were partially immersed in both ambient and continuous lab air sparging atmospheres to understand waterline corrosion of the metal. Open circuit potentials (OCP) were continuously taken during the immersion testing for a maximum of 5 days. A scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDS), Raman spectroscopy, and 3-D …

Tandem Mass Spectrometry (Ms/Ms) For Determination Of Architecture Of Synthetic Polymers, Shoumik Saha

Williams Honors College, Honors Research Projects

Tandem Mass Spectrometry (MS/MS) was used to determine the architecture of synthetic polymers and they are difluorene-N₃, 3-difluorene-N₃ and VPOSS-3-difluorene. VPOSS materials usually exhibit electrochemical properties and the research was performed to determine their accurate structure and to provide evidence of their proper synthesis. The compounds were mixed with a matrix solution, DCTB, and a silver salt to enable proper protonation. The solvent mixture was on a MALDI plate and then put into the mass spectrometer. The mass spectrum generated was analyzed and each fragment was identified to structures with the synthetic polymers via ChemDraw. Thus, trial …

Abnormal Phase Transition Between Two-Dimensional High-Density Liquid Crystal And Low-Density Crystalline Solid Phases, Wenbin Li, Longjuan Kong, Baojie Feng, Huixia Fu, Hui Li, Xiao Cheng Zeng, Kehui Wu, Lan Chen

Xiao Cheng Zeng Publications

Some two-dimensional liquid systems are theoretically predicted to have an anomalous phase transition due to unique intermolecular interactions, for example the first-order transition between two-dimensional high-density water and low-density amorphous ice. However, it has never been experimentally observed, to the best of our knowledge. Here we report an entropy-driven phase transition between a high-density liquid crystal and low-density crystalline solid, directly observed by scanning tunneling microscope in carbon monoxide adsorbed on Cu(111). Combined with first principle calculations, we find that repulsive dipole–dipole interactions between carbon monoxide molecules lead to unconventional thermodynamics. This finding of unconventional thermodynamics in two-dimensional carbon monoxide …

Toward The Detection Of The Triatomic Negative Ion Spn−: Spectroscopy And Potential Energy Surfaces, Tarek Trabelsi, Majdi Hochlaf, Joseph S. Francisco

Department of Chemistry: Faculty Publications

High level theoretical calculations using coupled-cluster theory were performed to provide an accurate description of the electronic structure, spectroscopic properties, and stability of the triatomic negative ion comprising S, N, and P. The adiabatic electron affinities (AEAs) and vertical detachment energies

(VDEs) of PNS, SPN, PSN, and cyc-PSN were calculated. The predicted AEA and VDE of the linear SPN isomer are large: 2.24 and 3.04 eV, respectively. The potential energy surfaces (PESs) of the lowest-lying electronic states of the SPN isomer along the PN and SP bond lengths and bond angle were mapped. A set of spectroscopic parameters for …

Characterization Of Solution-Phase Drug-Protein Interactions By Ultrafast Affinity Extraction, Sandya Beeram, Xiwei Zheng, Kyungah Suh, David S. Hage

Department of Chemistry: Faculty Publications

A number of tools based on high-performance affinity separations have been developed for studying drug-protein interactions. An example of one recent approach is ultrafast affinity extraction. This method has been employed to examine the free (or non-bound) fractions of drugs and other solutes in simple or complex samples that contain soluble binding agents. These free fractions have also been used to determine the binding constants and rate constants for the interactions of drugs with these soluble agents. This report describes the general principles of ultrafast affinity extraction and the experimental conditions under which it can be used to characterize such …

Systems And Methods For Actuating Soft Robotic Actuators, Robert F. Shepherd, Adam Stokes, Stephen A. Morin, Ludovico Cademartiri, Jacob Freake, Rui Nunes, Xin Chen, George M. Whitesides

Department of Chemistry: Faculty Publications

Systems and methods for providing a soft robot is provided. In one system , a robotic device includes a flexible body having a fluid chamber, where a portion of the flexible body includes an elastically extensible material and a portion of the flexible body is strain limiting relative to the elastically extensible material. The robotic device can further include a pressurizing inlet in fluid communication with the fluid chamber, and a pressurizing device in fluid communication with the pressurizing inlet, the pressurizing device including a reaction chamber configured to accommodate a gas producing chemical reaction for providing pressurized gas to …

Tin Nanoparticles Encapsulated Carbon Nanoboxes As High-Performance Anode For Lithium-Ion Batteries, Ziming Yang, Hong-Hui Wu, Zhiming Zheng, Yong Cheng, Pei Li, Qiaobao Zhang, Ming-Sheng Wang

Department of Chemistry: Faculty Publications

One of the crucial challenges for applying Sn as an anode of lithium-ion batteries (LIBs) is the dramatic volume change during lithiation/delithiation process, which causes a rapid capacity fading and then deteriorated battery performance. To address this issue, herein, we report the design and fabrication of Sn encapsulated carbon nanoboxes (denoted as Sn@C) with yolk@shell architectures. In this design, the carbon shell can facilitate the good transport kinetics whereas the hollow space between Sn and carbon shell can accommodate the volume variation during repeated charge/discharge process. Accordingly, this composite electrode exhibits a high reversible capacity of 675 mAh g^{−1 …}