Analytical Chemistry Commons^™

Survey Of Flavonoids And Their Distribution In Different Kinds Of Onions Using High Performance Liquid Chromatography And Gas Chromatography Mass Spectrometry., Archana Racharla

Electronic Theses and Dissertations

This research is done to determine the distribution of flavonoids in diverse varieties of onions (commercial and wild onions). Reflux extraction method was done on dried onions and the abstracts were analyzed subsequently by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GCMS). Statistical calculations were done to see if there are significant differences in the varieties of onions studied from the chromatographic profiles obtained. The chromatograms obtained were patterned using visual observations, scatter plot study, correlation co-efficient, and ANOVA to evaluate the significant difference of the distribution of flavonoids in varieties of onions. The organic white onions seem …

Determination Of Select Metal Ions In Commercially Available Conventional And Organic Baby Foods., Neva S. Winters

Electronic Theses and Dissertations

The goal of this study is to determine whether or not there is an appreciable difference between concentrations of various metal ions present in conventionally grown and processed and organically grown and processed baby foods. Two prominent, commercially available brands were chosen to undergo comparative studies between both their own conventional and organic varieties of second stage green beans and carrots. Samples were tested for cadmium, calcium, iron, lead, nickel, and zinc. Two containers of each variety of baby food were sampled in triplicate, with purchases of foods being made in separate areas to ensure that each set came from …

Development Of A Novel Electron-Transfer Secondary Reaction Matrix, Characterization Of The Site–Specificity Of Novel Bilin-Lyase, And Fundulus Grandis Protein Expression Investigation Using Mass Spectrometry, Mohamed N. Boutaghou

LSU New Orleans Theses and Dissertations

Reported in this dissertation are the results of investigations performed at the New Orleans Center for Mass Spectrometry at the University of New Orleans. The projects that are detailed in the coming pages take on a variety of subjects, but a common thread is that each employs matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to solve a problem. Fundamental aspects of MALDI in-plume ionization are implicated in the introduction of a newly developed electron-transfer secondary ionization matrix. The remaining projects are related to the ever expanding field of proteomics. Mass spectrometry was used to investigate the site specificity of a newly …

Affinity Chromatography In Environmental Analysis And Drug-Protein Interaction Studies, Efthimia Papastavros

Department of Chemistry: Dissertations, Theses, and Student Research

This dissertation will examine the use of novel affinity sorbents to extract emerging contaminants from water. These contaminants include carbamazepine, an anti-epileptic drug which is resistant to natural degradation in the environmental and to drinking water treatment procedures. This drug has been found in fish, drinking water, estuarine and coastal waters, and river sediment and has been used as a general marker of contaminants in wastewater. Carbamazepine was one of the most commonly detected compounds in surface-water and groundwater samples in a recent reconnaissance study of untreated drinking water sources in the U.S. Besides using this drug as a representative …

Development And Optimization Of Organic Based Monoliths For Use In Affinity Chromatography, Erika L. Pfaunmiller

Department of Chemistry: Dissertations, Theses, and Student Research

Affinity chromatography is an important and useful tool for studying biological interactions, such as the binding of an antibody with an antigen. Monolithic supports offer many advantages over traditional packed bed supports in affinity chromatography, including their ease of preparation, low back pressures and good mass transfer properties. Monoliths can be broken down into two basic categories: organic (polymer) and inorganic (silica) monoliths. There are many varieties of polymer based monoliths; however, a large focus has been on co-polymers of glycidyl methacrylate (a functional monomer) and ethylene dimethacrylate (a cross-linking agent). The solvents of choice for making this type of …

Chemical Modification On Gold Slides To Gain Better Control Of Patterning Techniques, Ragini Vuppalapati

Masters Theses & Specialist Projects

Nanolithography is a rapidly evolving field that requires new combinations of techniques to improve patterning and to assist in fabricating electromechanical devices. An increasing number of applications require surfaces with defined regions of different chemical functionality. In our previous project optimum conditions for lithographic patterning were determined and potential blockers were identified to reduce force on the tip.

This work is focused on identifying good chemical modifications that will allow better control of basic patterning and to investigate the minimum force of patterning required while using each chemical system. The primary aim is to gain better control of basic pattern …

Method Development And Validation Of The Quantitation Of 19 Antipsychotics Using Deuterated Internal Standards, Anthony S. Epps

Chemistry Theses

Antipsychotic drugs or neuroleptics are used primarily for psychiatric disorders such as schizophrenia, psychosis, and bipolar disorder. In forensic science antipsychotics are drugs of considerable interest because of their potential abuse, involvement in suicides, and they are frequently associated with sudden death investigations. Well-characterized and fully validated analytical data is necessary to generate reproducible and reliable results. As a result, data can be correctly interpreted and objectively demonstrate in its applicability for the intended use. This research has developed and validated a method that is selective, sensitive and accurate using liquid chromatography–tandem mass spectrometry (LC–MS/MS) for the simultaneous determination of …

The Tetrafluoroborate Salt Of 4-Methoxybenzyl N-2-(Dimethylamino)Ethyl-N-Nitrosocarbamate: Synthesis, Crystal Structure And Dft Calculations, Helene Hedian, Vladimir Benin

Chemistry Faculty Publications

The tetrafluoroborate salt of 4-methoxybenzyl N-2-(dimethylamino)ethyl-N-nitrosocarbamate was prepared in two steps, via the corresponding carbamate. Its crystal structure is monoclinic, space group P21/c. The unit cell dimensions are: a = 19.499(8) Å, b = 5.877(3) Å, c = 15.757(7) Å, α = 90°, β = 110.019(7)°, γ = 90°, V = 1696.5(12) Å3, Z = 4. The structure exhibits an unexpected, pseudo-gauche conformation with respect to the C2–C3 bond, due to a stabilizing hydrogen bond between the carbonyl oxygen (O1) and the hydrogen atom at the trialkylammonium center (H3n), with a distance between them of …

Visualizing The Spatial Localization Of Active Matrix Metalloproteinases (Mmps) Using Maldi Imaging Ms, Sasirekha Muruganantham

Graduate Theses and Dissertations

Biomaterial implantation induces the foreign body response (FBR). Development of longer-term implants relies on the thorough understanding of the FBR. The progression of the FBR is regulated by a number of biomolecules including cytokines, chemokines, and matrix metalloproteinases (MMPs). The nature of the FBR requires the spatial and temporal regulation of these mediators. MMPs are an extremely large and diverse group of enzymes that play key roles in regulating the FBR. Precise spatiotemporal regulation of MMPs defines their proteolytic activities. The aim of this project is to develop a new bioanalytical method to visualize the localization of active MMPs at …

Preparation And Characterization Of Biomimetic Hydroxyapatite-Resorbable Polymer Composites For Hard Tissue Repair, Kristopher R. Hiebner

Department of Chemistry: Dissertations, Theses, and Student Research

Autografts are the orthopedic “gold standard” for repairing bone voids. Autografts are osteoconductive and do not elicit an immune response, but they are in short supply and require a second surgery to harvest the bone graft. Allografts are currently the most common materials used for the repair of segmental defects in hard tissue. Unlike autografts, allografts can cause an undesirable immune response and the possibility of disease transmission is a major concern. As an alternative to the above approaches, recent research efforts have focused on the use of composite materials made from hydroxyapatite (HA) and bioresorbable polymers, such as poly-L-lactide …

Influence Of Ionic Mobile Phase Additives With Low Charge Delocation On The Retention Of Ionic Analytes In Reversed Phase Hplc, Cesar Florez

Seton Hall University Dissertations and Theses (ETDs)

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Dynamics And Catalytic Resolution Of Selected Chiral Organolithiums, Timothy Kum Beng

Graduate Theses and Dissertations

One of the most important developments of the last decade has been the emergence of new methods to dynamically resolve racemic organolithiums using stoichiometric amounts of the chiral ligand. When this concept is implemented successfully, it obviates the need for covalently attached chiral auxiliary based methods, asymmetric deprotonation, and asymmetric synthesis of a precursor stannane as ways to access enantioenriched organolithium compounds for use in asymmetric synthesis. Since certain electrophiles consume the chiral ligand, it is desirable to render this process catalytic in the chiral ligand.

As part of a larger study on the amenability of chiral organolithiums to a …

Intragroup Separation Of Trivalent Lanthanides And Actinides For Neutron Capture Experiments In Stockpile Stewardship Sciences, Narek Gharibyan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Knowledge of low-energy cross sections for stable and unstable nuclei in neutron-, γ- and ion induced reactions is important in both the simulation and radiochemistry diagnosis of nuclear device performance. This dissertation explores extraction chromatography and ion chromatography methods for the intragroup separation of trivalent actinides and lanthanides in support of cross section measurements for isotopes of interest. For trivalent actinides, americium (Am(III)) and curium (Cm(III)), separation is necessary to assist in experiments related to the measurement of neutron capture cross section for ²⁴¹ Am and the production of ^{242 m} Am/^242g Am isomeric ratio. Extraction chromatography resins …

Electrochemistry Of Pani/Metal Composites In Basic Solutions, Tamthinhan Quy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Polyaniline (PANI) has been extensively investigated due to its unique conductivity, which is primarily dependent on the oxidation state of the material and the solution pH. PANI is an insulator when it is oxidized, and the solution pH exceeds four. Numerous attempts to extend PANI's conductivity to neutral and alkaline environments have been unsuccessful. However, our previous study has demonstrated that PANI/Pd composite is conductive and catalytically active in a basic solution, pH ∼ 12. Therefore, the conductivity and the electrochemical properties of PANI composites including PANI/Au, PANI/Pd and PANI/Pt were evaluated in basic solutions. The fundamental studies of PANI/metal …

Studies Toward The Development Of A Microelectrode Array For Detection Of Dopamine Through Redox Cycling, Anupama Aggarwal

Graduate Theses and Dissertations

Redox cycling is an electrochemical technique that cycles the reversible redox species between its oxidative states repeatedly on generator and collector electrodes. Two or more individually-addressable microelectrodes located close to each other allow redox cycling to be possible. Electrochemical behavior of a biologically important molecule, dopamine is examined under redox cycling conditions. To our knowledge, this is the first report on detection of physiological concentration of dopamine in presence of up to 100 times excess ascorbate with the use of redox cycling, without the involvement of polymer coating such as Nafion®.

Microfabrication was used to produce different geometries (parallel bands …

Dynamic Modeling And Characteristic Analysis Of Proton Exchange Membrane Fuel Cell, Qiu-Hong Jia, Ming Han, Bin Deng, Cai-Zhi Zhang

Journal of Electrochemistry

In this paper, a dynamic model of PEMFC is developed to estimate the dynamic performance of PEMFC by analyzing in detail the influence factors of voltage of PEMFC including various losses. The partial pressure of hydrogen and oxygen is obtained using the differential form of the ideal-gas equation in this model. The steady-state model is obtained by setting reasonable parameter values. The simulation results and experimental results have good consistency, which shows that the simulation model is correct, reasonable and effective. It analyzed the dynamic response characteristics of the output voltage and the partial pressure of hydrogen in condition of …

Preparation And Characterization Of A Composite Of Gold Nanoparticles And Single-Walled Carbon Nanotubes And Its Potential For Heterogeneous Catalysis, Anne Shanahan, James Sullivan, Mary Mcnamara, Hugh Byrne

Articles

A single-walled carbon nanotube-supported gold nanoparticle composite was prepared and characterized by X-ray diffraction, scanning transmission electron microscopy/scanning electron microscopy/transmission electron microscopy, energy-dispersive X-ray analysis, atomic absorption spectroscopy, nitrogen adsorption, Raman spectroscopy, and ultraviolet-visible spectroscopy. The Au particles were found to be crystalline, with a well-defined and narrow particle-size distribution, centered around 7 nm. The activity and selectivity of the composite for solventless aerobic oxidation of a secondary alcohol were examined, and a conversion efficiency of 95% was obtained.

An Lcms Based Assay For Detection And Quantification Of Bacterial Cell Wall Intermediates, Chandra Sekhar Arigapudi

All Capstone Projects

The main objective of my project is to determine the bacterial cell wall intermediates in E.coli and develop an LCMS method that Phosphomycin is a PEP analogue that irreversibly inhibits UDP-GluNAc-enolpyruvate transferase (MurA enzyme), which prevents the formation of N-acetyl muramic acid, which is an essential element in the Peptidoglycan cell wall. Antibacterial agents have a tremendous impact on human health. Most of the antibacterial agents, including beta lactams target the bacterial cell wall biosynthesis.The pathway for Escherichia coli is shown in page 19. Among the most widely used antibiotics, beta lactams inhibit the penicillin binding protein (PBPs)which block the …

Evaluation And In Vitro Studies Of Folate Peg Biotin And Other Peg Agents, Vikram Reddy Kasarala

All Capstone Projects

Folate is an essential component for cell growth and cell division, playing a major role in DNA synthesis. It is common sense that the rapidly dividing cells synthesize more DNA, including cancer cells. Also, it was reported that cancer cells over express Folate receptors and this was the basis for our probe for cancer cells. We used long PEG biotin in conjugation with Folate. Previous studies in our group showed that the PEG could be used in the sensor to detect and capture cancer cells. The present study was aimed at evaluating the effect of Long PEG containing Folate based …

Evaluation And In Vitro Studies Of Folate Peg Biotin And Other Peg Agents, Christopher E. Zmudka

All Capstone Projects

Folate receptor alpha is a membrane-bound protein displaying high affinity for folic acid. This receptor is believed to serve as a receptor-mediated transport system of folic acid into cancer and cells associated with inflammation. Interesting, most normal cells in the body have little if 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.

Numerous methods have been explored in the literature in an attempt to detect low levels of free folate receptor and/or rare circulating cancer cells. In an attempt to further exploit …