Analytical Chemistry Commons^™

Measurement Of Atmospheric Ammonia Species : Development, Validation, And Field Applications Of An Analytical Method, Jian Hou

Legacy Theses & Dissertations (2009 - 2024)

Ammonia is the primary base in the atmosphere. It reacts readily with atmospheric acids such as sulfuric acid, nitric acid, and hydrochloric acid to form ammonium salts that occur predominantly in the fine aerosol particle (PM2.5) fraction. The ability to measure ammonia species (NHx, the sum of gaseous NH₃ and particulate NH₄+) is essential for the investigation of atmospheric behaviors of NHx. In this dissertation work, a highly sensitive technique has been developed for the measurement of atmospheric NHx species. The method is based on aqueous scrubbing of the atmospheric NH₃ and NH₄+ using …

Biomonitoring For Exposure To Trace Elements In Utero : Analysis Of The Human Placenta, Pamela Catherine Kruger

Legacy Theses & Dissertations (2009 - 2024)

The placenta forms in eutherian mammals, and is responsible for the nutrition of the developing fetus. However, maternal exposure to environmental pollutants both before and during pregnancy may result in the passage of toxins through the placental barrier and into fetal tissues. The placenta is the only organ derived from both maternal and fetal tissues, and establishes a link between the fetus and the environmental exposures of the mother. The analysis of placentae for the presence of environmental pollutants offers the possibility of exposure measurements in both the mother and the developing fetus. Specifically, trace element determination in human placentae …

Immobilization Method For Producing Active Α1-Acid Glycoprotein, David S. Hage, Hai Xuan

Department of Chemistry: Faculty Publications

A method and kit for immobilization of a glycoprotein. The method may include activating an affinity Support. The affinity Support may be activated by reacting the affinity Support with a compound that is reactive with one or more functional groups included within the glycoprotein. The method may also include oxidizing the glycoprotein in which oxidation conditions are selected to yield an oxidized glycoprotein that is biologically active and contains a Sufficient number of reactive aldehyde groups for coupling to a Support. For example, the oxidized glycoprotein may include five reactive aldehyde groups. In addition, the method may include reacting the …

Preparation And Characterization Of Some Substituted Benzyl N-Nitrosocarbamates Containing An N-2-(Methylthio)Ethyl Or A Bis(2-Aminoethyl)Sulfide Functionality, Satya Venkata, Eric Shamo, Vladimir Benin

Chemistry Faculty Publications

The synthesis and characterization of some substituted benzyl N-nitrosocarbamates with an N-2-(methylthio)ethyl or a bis(2-aminoethyl)sulfide functionality is reported, as a part of a long-term goal to design and prepare novel photolabile structures that could be used as substances for controlled release of alkylating and/or crosslinking agents. The synthesis was accomplished by reaction of benzyl chloroformates with the corresponding amines, resulting in the preparation of carbamates. The latter were subsequently nitrosated, utilizing two different N-nitrosation methods, to yield the target structures.

Partial Ion Yield Sspectroscopy Around The Cl 2p And C 1s Ionization Thresholds In Cf3cl, D. Ceolin, Maria Novella Piancastelli, Wayne C. Stolte, Dennis W. Lindle

Chemistry and Biochemistry Faculty Research

We present a partial ion yield experiment on freon 13, CF₃Cl, excited in the vicinity of the C 1s and Cl 2p ionization thresholds. We have collected a large amount of cationic fragments and a few anionic fragments at both edges. We have observed a strong intensity dependence of Rydberg transitions with ion fragment size for the CF_nCl⁺ and CF_n⁺/F⁺ (n=0–3) series at both the Cl 2p and C 1s ionization edges. Selectivity in the fragmentation processes involving the C–Cl and C–F bonds are highlighted by the intensities of the C …

Yttrium And Hydrogen Superstructure And Correlation Of Lattice Expansion And Proton Conductivity In The Bazr0.9y0.1o2.95 Proton Conductor, A. Braun, A. Ovalle, V. Pomjakushin, A. Cervellino, S. Erat, Wayne C. Stolte, T. Graule

Chemistry and Biochemistry Faculty Research

Bragg reflections in Y-resonant x-ray diffractograms of BaZr_0.9Y_0.1O_2.95 (BZY10) reveal that Y is organized in a superstructure. Comparison with neutron diffraction superstructure reflections in protonated/deuterated BZY10 suggests that both superstructures are linked, and that protons move in the landscape imposed by the Y. The thermal lattice expansion decreases abruptly for protonated BZY10 at T≥648±20 K, coinciding with the onset of lateral proton diffusion and suggesting a correlation of structural changes and proton conductivity. The chemical shift in the Y L₁-shell x-ray absorption spectra reveals a reduction from Y³⁺ toward Y²⁺ upon …

Earth Field Magnetic Resonance Imaging And Paramagnetic Contrast Agents, Saideh Sadat Mortazavi

Open Access Theses & Dissertations

The goal of this research was to visualize the uptake of copper by plants to aid phyto-remediation research. The hypothesis was that regions of the plant with more copper will have an enhanced NMR signal using copper as a paramagnetic contrast agent.

As the name implies, Earth Field Magnetic Resonance Imaging (EFMRI) spectrometry uses a magnetic field 300,000 times weaker than a 600 MHz Nuclear Magnetic Resonance (NMR) spectrometer. Just like in conventional human MRI, this portable instrument is capable of recording one, two and three dimensional images though the sample size is much smaller.

The enhancement of signal was …

Salsola Kali (Tumbleweed): A Possible Biomonitoring Device For The Detection Of Airborne Heavy Metals, Tenoch Benitez

Open Access Theses & Dissertations

Vehicular congestion generates particulate matter and contaminants such as lead, cadmium, copper, chromium, nickel, and zinc which have been detected in the U.S.-Mexico border region. To overcome the inconvenience of expensive sampling techniques, scientists started to assess air quality by using bioindicator plants, a technique called biomonitoring. Biomonitoring is an inexpensive and environmentally friendly approach to determine inorganic contaminants at trace levels. The purpose of this project was to determine the effectiveness of tumbleweed (Salsola kali) plants, sprayed with chelating agents, as a passive monitoring device to determine the possible presence of heavy metals in the ambient air around international …

Towards More Reliable Extrapolation Algorithms With Applications To Organic Chemistry, Jaime Nava

Open Access Theses & Dissertations

One of the main objectives of science and engineering is to predict the results of different situations. For example, in Newton's mechanics, we want to predict the positions and velocities of different objects (e.g., planets) at future moments of time.

In this Thesis, as a case study, we take the problem of predicting the properties of new chemical substances. One of the main objectives of chemistry is to design new molecules (and, more generally, new chemical compounds) which are useful for various practical tasks. New substances have already resulted in new materials for buildings and for spaceships, new explosives and …

Androgen-Stimulated Udp-Glucose Dehydrogenase Expression Limits Prostate Androgen Availability Without Impacting Hyaluronan Levels, Qin Wei, Robert Galbenus, Ashraf Raza, Ronald Cerny, Melanie A. Simpson

Ronald Cerny Publications

UDP-glucose dehydrogenase (UGDH) oxidizes UDP-glucose to UDP-glucuronate, an essential precursor for production of hyaluronan (HA), proteoglycans, and xenobiotic glucuronides. High levels of HA turnover in prostate cancer are correlated with aggressive progression. UGDH expression is high in the normal prostate even though HA accumulation is virtually undetectable. Thus, its normal role in the prostate may be to provide precursors for glucuronosyltransferase enzymes, which inactivate and solubilize androgens by glucuronidation. In this report, we quantified androgen dependence of UGDH, glucuronosyltransferase, and HA synthase expression. Androgen dependent and independent human prostate cancer cell lines were used to test the effects of UGDH …

A Multi-Step Nmr Screen For The Identification And Evaluation Of Chemical Leads For Drug Discovery, Kelly A. Mercier, Matthew D. Shortridge, Robert Powers

Department of Chemistry: Faculty Publications

A multi-step NMR based screening assay is described for identifying and evaluating chemical leads for their ability to bind a target protein. The multi-step NMR assay provides structure-related information while being an integral part of a structure based drug discovery and design program. The fundamental principle of the multi-step NMR assay is to combine distinct 1D and 2D NMR techniques, in such a manner, that the inherent strengths and weakness associated with each technique is complementary to each other in the screen. By taking advantage of the combined strengths of 1D and 2D NMR experiments, it is possible to minimize …

Anhydrous Fluoride Salts And Reagents And Methods For Their Production, Stephen G. Dimagno, Haoran Sun

Department of Chemistry: Faculty Publications

Anhydrous organic fluoride salts and reagents prepared by a method comprising the nucleophilic Substitution of a fluorinated aromatic or fluorinated unsaturated organic compound with a salt having the formula: [Q_nM]^x+A_x^- in an inert polar, aprotic solvent; wherein M is an atom capable of supporting a formal positive charge, the n groups Q are independently varied organic moieties, n is an integer such that the [Q_nM] carries at least one formal positive charge, x is an integer defining the number of formal positive charge(s), +, carried by the [Q_nM], A^{- …}

The Effect Of Adsorbent Geometry And Surface Chemistry On Hplc Retention, Zhaoxia Liu

Seton Hall University Dissertations and Theses (ETDs)

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Analytical Method Development For Determination Of Volatile Organic Compounds In Calcareous Desert Soil, Mary F. Turner

UNLV Theses, Dissertations, Professional Papers, and Capstones

Soil sample preservation for volatile organic compound analysis generally requires short sample holding times or preservation of the sample's chemical constituents with sodium bisulfate (NaHSO 4 ). Calcareous soils cannot be preserved using NaHSO4 because effervescence will promote the loss of analytes, and short holding times before analysis are not practical for remote sampling locations. An experimental approach was developed for determination of volatile organic compounds (VOCs) in soil that utilizes solid sorbents for sample preservation and solid-phase microextraction (SPME) sample preparation technique coupled with gas chromatography/mass spectrometry (GC/MS) for analysis. Solid sorbents are used to sequester readily extractable (vapor …

Optimization Of The Microprecipitation Procedure For Nuclear Forensics Applications, Lyndsey Renee Kelly

UNLV Theses, Dissertations, Professional Papers, and Capstones

Microprecipitation has become one of the most widely used sample preparation techniques for alpha spectroscopy. Many factors during the precipitation process can affect the yield and energy resolution by adding unwanted mass to the sample. Current applications in nuclear forensics call for an optimization of energy resolution and yield in order to improve identification and quantify specific radionuclides. The purpose of this research is to determine the optimal parameters used for microprecipitation. The optimal solution temperature, precipitation time, carrier amount, and hydrofluoric acid amount are used to investigate the influence of varying the type of carrier, as well as, the …

Desert Varnish As An Indicator Of Modern-Day Air Pollution In Southern Nevada, Piotr Nowinski

UNLV Theses, Dissertations, Professional Papers, and Capstones

Rock varnish, often called desert varnish, is a slow-growing, manganese-rich coating that accumulates on exposed rock surfaces. The mechanism of varnish formation is not fully understood, however, most authors agree that varnishes derive their components from the atmosphere. The main goal of this study was to demonstrate the potential use of desert varnish as a passive environmental monitor of present and past atmospheric pollution. Analysis of varnishes is a new field that can potentially provide records of pre-anthropogenic levels of atmospheric metals and other environmental pollutants. To evaluate the potential of desert varnish as an environmental monitoring tool, the following …