Analytical Chemistry Commons^™

The Chemistry Of New Garlic-Derived Organosulfur Compounds And The Molecular Basis Of Olfaction, Berenice Dethier

Legacy Theses & Dissertations (2009 - 2024)

Garlic is a very popular condiment that has been used around the world for centuries. It is also a source of a remarkably extensive range of organosulfur compounds, whose chemistry is the focus of this thesis. The central reaction in formation of these compounds is the enzymatic cleavage of alk(en)yl cysteine sulfoxides by alliinases, which leads to sulfenic acids. The latter can then undergo condensation and rearrangement into various organosulfur compounds. Three aspects of the chemistry of garlic have been investigated in this thesis.

The Use Of Ion Mobility Spectrometry-Mass Spectrometry For The Structural Elucidation Of Progressively Larger Nucleic Acids, Jennifer Lynn Lippens

Legacy Theses & Dissertations (2009 - 2024)

The biomedical community and pharmaceutical industry have come to rely in ever

Processes And Reagents For Making Daryliodonium Salts, Stephen Dimagno

Department of Chemistry: Faculty Publications

This invention relates to processes and reagents for making diaryliodonium salts, which are useful for the preparation of fluorinated and radiofluorinated aromatic compounds.

Tandem Mass Spectrometric Analysis Of Phosphoamino Acid-Metal Ion Complexes, Urmi Patel

All Capstone Projects

The complex of phosphoamino acid with metal ions was prepared by mixing both solutions and analyzed using ESI MS/MS technique. In this study, O-phospho-L-serine and O-phospho-L-tyrosine were used as phosphoamino acids and single charged metal ions such as Li+, Na+, K+, Rb+, Cs+ and Ag+ were used to study the dissociation patterns when combined with phosphoamino acid. The complexes were successfully fragmented in mass spectra using ESI MS/MS technique and the fragmentation products were studied and the dissociation patterns were proposed.

In Vitro And In Vivo Measurments Of Serotonin For Ecological And Mental Health Via Fast Scan Cyclic Voltammetry, Matthew Nicholas Jackson

Wayne State University Theses

Fast Scan Cyclic Voltammetry has been proven to be a highly valuable technique in analysis and detection of neurotransmitters. With this technique, two novel applications are being explored to protect natural water sources as well as furthering the efficacy of antidepressants. Despite setbacks, promising data has been collected to further understand the mechanisms involved in the phototactic response observed in Daphnia Magna. Electrochemical modification of carbon fiber microelectrodes has proven to be inefficient as a means to effectively differentiate between serotonin and its metabolite. As such, this unsuccessful attempt has further narrowed down the list of candidates to electrochemically differentiate …

Hydrogen Bonding And Orientation Effects On The Accommodation Of Methylamine At The Air-Water Interface, Ross D. Hoehn, Marcelo A. Carignano, Sabre Kais, Chongjing Zhu, Xiao Cheng Zeng, Joseph S. Francisco, Ivan Gladich

Xiao Cheng Zeng Publications

Methylamine is an abundant amine compound detected in the atmosphere which can affect the nature of atmospheric aerosol surfaces, changing their chemical and optical properties. Molecular dynamics simulation results show that methylamine accommodation on water is close to unity with the hydrophilic head group solvated in the interfacial environment and the methyl group pointing into the air phase. A detailed analysis of the hydrogen bond network indicates stronger hydrogen bonds between water and the primary amine group at the interface, suggesting that atmospheric trace gases will likely react with the methyl group instead of the solvated amine site. These findings …

Carinata Fame Production Process And Biofuel Oxidation, Benoit Kindo

Honors College Theses

In this experiment, the contribution of a standard production method for biofuels on their oxidative stability was investigated. Peroxide values were measured at different steps of the production process of Brassica carinata and peanut-based biofuels. The washing and drying steps in this production method showed significant increases in peroxide values for both biofuels and was identified as a major contributor of biofuel oxidation. Further analyses of the physical and thermal properties showed a more pronounced affect in the biofuel from Bassica carinata, and indicated an unusual composition much higher in saturated fatty acids much longer than those found in peanut. …

Determination Of Mln0128, An Investigational Antineoplastic Agent, In Human Plasma By Lc–Ms/Ms, Sandeep R. Kunati, Yan Xu

Chemistry Faculty Publications

MLN0128, an mTOR kinase inhibitor, is currently undergoing clinical investigation for treatment of a variety of cancers. To support this work, an LC–MS/MS method has been developed for the determination of MLN0128 in human plasma. A structural analog STK040263 was used as the internal standard. Both MLN0128 and the IS were first extracted from plasma using methyl tert-butyl ether; then separated on a Waters XTerra® MS C18 column using a mobile phase consisting of methanol–acetonitrile–10.0 mm ammonium formate (34:6:60, v/v/v) at a flow rate of 0.300 mL min−1. Quantitation of MLN0128 was done by positive electrospray ionization tandem mass spectrometry …

Plasma Temperature Measurements In The Context Of Spectral Interference, Brandon Seesahai

Honors Undergraduate Theses

The path explored in this thesis is testing a plasma temperature measurement approach that accounts for interference in a spectrum. The Atomic Emission Spectroscopy (AES) technique used is called Laser Induced Breakdown Spectroscopy (LIBS) and involves focusing a laser pulse to a high irradiance onto a sample to induced a plasma. Spectrally analyzing the plasma light provides a "finger print" or spectrum of the sample. Unfortunately, spectral line broadening is a type of interference encountered in a LIBS spectrum because it blends possible ionic or atomic transitions that occur in plasma. To make use of the information or transitions not …

Purification And Characterization Of Bromocresol Purple For Spectrophotometric Seawater Alkalinity Titrations, Taymee A. Brandon

Undergraduate Theses, Professional Papers, and Capstone Artifacts

The topic of my research is the purification of the sulfonephthalein indicator bromocresol purple (BCP). BCP is used as an acid-base indicator in seawater alkalinity determinations. Impurities in sulfonephthalein indicator salts often result in significant errors in pH values³. High-precision inorganic carbon (i.e. CO₂) measurements are necessary to document the changes in ocean chemistry and pH due to anthropogenic CO₂­ uptake by the earth’s oceans³. In order to reduce the error in seawater pH determinations and the general understanding of the CO₂ cycle, BCP must be purified and characterized. Previous work …

Tracking Silver, Gold, And Titanium Dioxide Nanoparticles Through Drinking Water Systems By Single Particle - Inductively Coupled Plasma - Mass Spectrometry, Ariel Renee Donovan

Masters Theses

"Single particle (SP)-ICP-MS methods were developed to characterize and quantify Ti-containing, titanium dioxide, silver, and gold NP concentration, size, size distribution and dissolved metal element concentration in surface water and treated drinking water. The effectiveness of conventional drinking water treatments (including lime softening, alum coagulation, filtration, and disinfection) to remove NPs from surface water was evaluated using six-gang stirrer jar test simulations. Six-gang stirrers were used to simulate drinking water treatments including lime softening, alum coagulation, powdered activated carbon sorption, filtration, and disinfection by free chlorine. Lime softening effectively removed most nanoparticles added. Source and drinking waters from three large …

Measurement Of Antioxidant Activity Toward Superoxide In Natural Waters, D. Whitney King, Emma Berger, Zachary Helm, Eleanor Irish, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

Antioxidants are a class of molecules that provide a protective function against reactive oxygen species (ROS) in biological systems by out competing physiologically important molecules for ROS oxidation. In natural waters, the reactivity of antioxidants gives an estimate of oxidative stress, and may determine the reactivity and distribution of reactive oxidants. We present an analytical method to measure antioxidant activity in natural waters through the competition between ascorbic acid, an antioxidant, and MCLA, a chemiluminescent probe for superoxide. A numerical kinetic model of the analytical method has been developed to optimize analytical performance. Measurements of antioxidant concentrations in pure and …

3d Printing Applications Within Spectrophotometry, Eric J. Stanczyk

Williams Honors College, Honors Research Projects

Ultraviolet-visible spectroscopy is a tool used throughout the field of chemistry and in chemical labs across the world. Spectrophotometers are a core technology in analytical chemistry, and are used to obtain accurate data on solution concentration. Unfortunately spectrophotometers can be difficult to obtain due to their high cost and low availability outside of a laboratory; this is especially true in either high school or lower grades where buying a spectrophotometer could be considered unreasonable due to price. There are ways to obtain cheaper spectrophotometers, but they can have a high initial cost or low overall quality. This paper will discuss …

Mutagenesis-Based Active-Site Characterization Of The Diabetes Drug Target Mitoneet, Lisa Mickley

Williams Honors College, Honors Research Projects

This project investigates the cluster stability of an outer mitochondrial membrane protein mitoNEET under mutational stress and drug binding analysis. MitoNEET is a part of a class of proteins that coordinate an Fe-S molecule into its tertiary structure. This protein is believed to facilitate the oxidative capacity of the electron transport chain by reversible loss of its coordinated Fe-S molecule. The research of this paper uses site directed protein mutagenesis to selectively alter the three cysteine, one histidine cluster coordination into more common coordination patterns such as two cysteine, two histidine or four cysteine. The ultimate goal is to optimize …

Medium-Sized Au40(Sr)24 And Au52(Sr)32 Nanoclusters With Distinct Gold-Kernel Structures And Spectroscopic Features, Wen Wu Xu, Yadong Li, Yi Gao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We have analyzed the structures of two medium-sized thiolateprotected gold nanoparticles (RS-AuNPs) Au₄₀(SR)₂₄ and Au₅₂(SR)₃₂ and identified the distinct structural features in their Au kernels [Sci. Adv., 2015, 1, e1500425]. We find that both Au kernels of the Au₄₀(SR)₂₄ and Au₅₂(SR)₃₂ nanoclusters can be classified as interpenetrating cuboctahedra. Simulated X-ray diffraction patterns of the RS-AuNPs with the cuboctahedral kernel are collected and then compared with the X-ray diffraction patterns of the RS-AuNPs of two other prevailing Au-kernels identified from previous experiments, namely the Ino-decahedral kernel and icosahedral kernel. …

Correction: Surprising Impact Of Remote Groups On The Folding–Unfolding And Dimer-Chain Equilibria Of Bifunctional H-Bonding Unimers, Rui Liu, Shuang Chen, Erin S. Baker, Richard D. Smith, Xiao Cheng Zeng, Bing Gong

Xiao Cheng Zeng Publications

The authors regret that in the original article the spelling of one author’s surname is incorrect. The correct name of the author is ‘Shuang Chen’.

The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

Surprising Impact Of Remote Groups On The Folding–Unfolding And Dimer-Chain Equilibria Of Bifunctional H-Bonding Unimers, Rui Liu, Shuang Cheng, Erin S. Baker, Richard D. Smith, Xiao Cheng Zeng, Bing Gong

Xiao Cheng Zeng Publications

Oligoamide 1, consisting of two H-bonding units linked by a trimethylene linker, was previously found to form a very stable, folded dimer. In this work, replacing the side chains and end groups of 1 led to derivatives that show the surprising impact of end groups on the folding and dimer-chain equilibria of the resultant molecules.

Unraveling The Hidden Function Of A Stabilizer In A Precursor In Improving Hybrid Perovskite Film Morphology For High Efficiency Solar Cells, Zhengguo Xiao, Dong Wang, Qingfeng Dong, Qi Wang, Wei Wei, Jun Dai, Xiwei Zheng, Jinsong Huang

Xiao Cheng Zeng Publications

The morphology of the organometal trihalide perovskite (OTP) plays a critical role in the performance of solar cell devices. Nevertheless it has been frequently reported that the morphology of OTP films tends to be different in different laboratories even with the same film preparation procedure, which makes it very difficult to compare and understand the material and device physics. Here, we unravel a critical role of the H₃PO₂ stabilizer in HI, which has been largely ignored, in controlling the morphology of the perovskite films. The H₃PO₂ stabilizer in HI solution introduces MAH₂PO …

Two-Dimensional Interlocked Pentagonal Bilayer Ice: How Do Water Molecules Form A Hydrogen Bonding Network?, Weiduo Zhu, Wen- Hui Zhao, Lu Wang, Di Yin, Min Jia, Jinlong Yang, Xiao Cheng Zeng, Lan-Feng Yuan

Xiao Cheng Zeng Publications

The plethora of ice structures observed both in bulk and under nanoscale confinement reflects the extraordinary ability of water molecules to form diverse forms of hydrogen bonding networks. An ideal hydrogen bonding network of water should satisfy three requirements: (1) four hydrogen bonds connected with every water molecule, (2) nearly linear hydrogen bonds, and (3) tetrahedral configuration for the four hydrogen bonds around an O atom. However, under nanoscale confinement, some of the three requirements have to be unmet, and the selection of the specific requirement(s) leads to different types of hydrogen bonding structures. According to molecular dynamics (MD) simulations …

Near-Barrierless Ammonium Bisulfate Formation Via A Loop-Structure Promoted Proton-Transfer Mechanism On The Surface Of Water, Lei Li, Manoj Kumar, Chongqin Zhu, Jie Zhong, Joseph S. Francisco, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

In the atmosphere, a well-known and conventional pathway toward the formation of ammonium sulfate is through the neutralization of sulfuric acid with ammonia (NH₃) in water droplets. Here, we present direct ab initio molecular dynamics simulation evidence of the formation of ammonium bisulfate (NH₄HSO₄) from the hydrated NH₃ and SO₃ molecules in a water trimer as well as on the surface of a water droplet. This reaction suggests a new mechanism for the formation of ammonium sulfate in the atmosphere, especially when the concentration of NH₃ is high (e.g., ∼10 μg …