Analytical Chemistry Commons^™

Newly-Developed Nanostructured Microcantilever Arrays For Gas-Phase And Liquid-Phase Sensing, Zhou Long

Doctoral Dissertations

The microcantilever (MC) has become a common transducer for chemical and biological sensing in gas phase and liquid phase during recent years. MC sensors provide superior mass sensitivity by converting weak chemical and biological stimuli into high mechanical response. Moreover, other advantages such as small size, low cost and array format have made MCs more attractive than other comparable sensors.

Selectivity in MC sensors can be enhanced by creating a differentially functionalized MC array (MCA) with responsive phases (RPs). A well-designed array should incorporate RPs exhibiting a variety of possible interactions with the analytes, and a specific analyte should induce …

Comparison Of Rna Quality From Stressed And Unstressed Recombinant Escherichia Coli, Mary Alice Salazar

All Theses

High quality, intact RNA is required for DNA microarray studies, cloning, and reverse transcriptase polymerase chain reaction (rt-PCR) analysis. There are several analytical methods used to assess the RNA quality. The RNA Integrity Number (RIN) from the Agilent Bioanalyzer is one quality control assay used to evaluate RNA. For recombinant Escherichia coli cultured under stressful conditions the RNA profiles obtained using the Agilent Bioanalyzer indicate RNA degradation; however, RNA obtained and purified in parallel from unstressed recombinant cultures indicate acceptable RNA values without significant degradation. We proposed that for stressed E. coli the RIN value is not necessarily indicative of …

Chemical Characterization Of Botanical Products: Comprehensive Speciation By Liquid Chromatography Particle Beam Mass Spectrometry, Joaudimir Castro Georgi

All Dissertations

The dietary supplement industry has expanded and many of these supplements have become an important aspect of people's everyday lives. In 1994, the U.S. Dietary Supplement Health and Education Act (DSHEA) classified numerous nutraceutical/botanical products as dietary supplements because of their beneficial medicinal properties and provided the necessary regulation to the supplement producers. Since then, the interest of the scientific community towards dietary supplements has grown intensively and numerous studies have been carried out in order to understand the chemical behavior of the active molecules in the human body. The development towards analytical methods for the quantification of the active …

Analysis Of Ammonia And Volatile Organic Amine Emissions In A Confined Poultry Facility, Hanh Hong Thi Dinh

All Graduate Theses and Dissertations

The National Air Emission Monitoring Study (NAEMS) project was funded by the Agricultural Air Research Council (AARC) to evaluate agricultural emissions nationwide. Utah State University (USU) is conducting a parallel study on agricultural emissions at a Cache Valley poultry facility. As part of this parallel study, samples of animal feed, eggs and animal waste were collected weekly from three manure barns (designated: manure barn, barn 4 - manure belt and barn 5 - high rise) from May 2008 to November 2009. These samples were analyzed to determine ammonia content, total Kjeldahl nitrogen content and ammonia emission. The yearly average calculated …

A Synthetic Biological Engineering Approach To Secretion- Based Recovery Of Polyhydroxyalkanoates And Other Cellular Products, Elisabeth Linton

All Graduate Theses and Dissertations

The costs associated with cellular product recovery commonly account for as much as 80% of the total production expense. As a specific example, significant recovery costs limit commercial use of polyhydroxyalkanoates (PHA), which comprise a class of microbially-accumulated polyesters. PHAs are biodegradable compounds that are of interest as a sustainable alternative to petrochemically-derived plastics. Secretion-based recovery of PHAs was studied to decrease PHA production costs. Type I and II secretory pathways are commonly used for the translocation of recombinant proteins out of the cytoplasm of E. coli. Proteins were targeted for translocation using four signal peptides (HlyA, TorA, GeneIII, …

Preparation And Characterization Of Extraction Chromatography Resins Using N-Donor Extractants For Trivalent Actinide And Lanthanide Separations, Christopher L. Klug

UNLV Theses, Dissertations, Professional Papers, and Capstones

Actinide and lanthanide elements exist in the geosphere and biosphere due to both natural abundances and anthropogenic activities. The investigation of the presence and transport of actinides through the environment is of great scientific interest. In order to prepare environmental samples for precise measurements, the individual actinides must be separated from the chemically similar lanthanides, and from neighboring actinides. Existing extraction chromatography resins are either poorly suited for this separation, have bleeding problems, are not reusable, or fail the CHON principle. In an effort to resolve these issues, malonamides and N-donor extractants from the BTP and BTBP classes of solvent …

Classification And Fertility Of Soils In The Big South Fork National River And Recreation Area Based On Landscape Position And Geology, Ryan H. Blair

Masters Theses

The Big South Fork National River and Recreation Area encompasses more than 50,585 hectares (125,000 acres) of the Cumberland Plateau along the border of Tennessee and Kentucky. Highly dissected and steep terrain have made accessibility to much of the park limited, thus little work has been done to investigate the formation of these soils. Seven native soil profiles were selected for chemical and physical analysis representing Pennsylvanian-aged acidic sandstone and shale geology and landforms. The objectives of this study included the characterization of selected native profiles by physical and chemical analysis, as well as classification using US Soil Taxonomy, to …

Field And Smog Chamber Studies Of Agricultural Emissions And Reaction Products, Derek J. Price

All Graduate Theses and Dissertations

Agricultural emissions are an important contributor to atmospheric aerosol. These emissions include nitrogen containing organic compounds, primarily as amines, which have not been well investigated to date. Although there have been several studies that have looked at the emission of gas phase amines, there are only a few studies that have focused on ambient amine-based aerosol. There have also only been a handful of smog chamber studies that have investigated amine aerosol chemistry. Kinetic studies have looked at the reactions of amines with OH and ozone. However, amine reactions with nitrate radical (NO₃) are not well understood. Several …

Pulsed-Laser Excited Photothermal Study Of Glasses And Nanoliter Cylindrical Sample Cell Based On Thermal Lens Spectroscopy, Prakash Raj Joshi

All Graduate Theses and Dissertations

The research in this dissertation presents Pulsed-Laser Excited photothermal studies of optical glasses and cylindrical sample cell.

First, a study of a photothermal lens experiment and the finite element analysis modeling for commercial colored glass filters is done. The ideal situation of a semiinfinite cylinder approximate model used to describe the photothermal lens experiment requires the boundary condition that there is no transfer of heat from the glass to surrounding when the glass is excited with a laser. The finite element analysis modeling for photothermal signal with coupling heat with surrounding shows the thermal heat transfer between the glass surface …

Chromatographic Studies Of Drug-Protein Binding In Diabetes, Kathryn (Krina) S. Joseph

Student Research Projects, Dissertations, and Theses - Chemistry Department

Drug-protein binding can have a dramatic impact on the distribution and metabolism of a drug. This manuscript describes the use of high-performance affinity chromatography to examine the binding of various compounds to human serum albumin (HSA) in normal and diabetic disease states.

The first study examined the use of four coumarin compounds as possible alternatives to warfarin as a probe for Sudlow site I on HSA. High-performance affinity chromatography and immobilized HSA columns were used to compare and evaluate the binding properties of these probe candidates. It was found from this group that 4-hydroxycoumarin was the best alternative to warfarin …

Characterization Of Glycation Sites On Human Serum Albumin Using Mass Spectrometry, Omar S. Barnaby

Student Research Projects, Dissertations, and Theses - Chemistry Department

The modification of proteins by reducing sugars is a process that occurs naturally in the body. This process, which is known as glycation, has been linked to many of the chronic complications encountered during diabetes. Glycation has also been linked to changes in the binding of human serum albumin (HSA) to several drugs and small solutes in the body. While these effects are known, there is little information that explains why these changes in binding occur. The goal of this project was to obtain qualitative and quantitative information about glycation that occurs on HSA. The first section of this dissertation …

An Electrochemical Cell For The Efficient Turn Around Of Wafer Working Electrodes, Nicholas Wozniak, Alyssa Frey, Lucas Osterbur, Timothy Boman, Jennifer R. Hampton

Faculty Publications

We present a new design for an electrochemical cell for use with wafer working electrodes. The key feature of the design is the use of half turn thumb screws to form a liquid-tight seal between an o-ring and the sample surface. The assembly or disassembly of the cell requires a half turn of each thumb screw, which facilitates the quick turn around of wafer samples. The electrochemical performance of the cell is demonstrated by cyclic voltammetry and double step chronoamperometry measurements of the ferricyanide/ferrocyanide couple.

An Examination Of Factors Influencing The Thermodynamics Of Correlation-Gas Chromatography As Applied To Large Molecules And Chiral Separations, Dmitry Lipkind, James S. Chickos

James Chickos

No abstract provided.

The Construction And Optimization On An Ion Mobility Spectrometer For The Analysis Of Explosives And Drugs, Hanh Tuyet Lai

FIU Electronic Theses and Dissertations

Today, over 15,000 Ion Mobility Spectrometry (IMS) analyzers are employed at worldwide security checkpoints to detect explosives and illicit drugs. Current portal IMS instruments and other electronic nose technologies detect explosives and drugs by analyzing samples containing the headspace air and loose particles residing on a surface. Canines can outperform these systems at sampling and detecting the low vapor pressure explosives and drugs, such as RDX, PETN, cocaine, and MDMA, because these biological detectors target the volatile signature compounds available in the headspace rather than the non-volatile parent compounds of explosives and drugs. In this dissertation research volatile signature compounds …

A Bland–Altman Comparison Of The Lead Care® System And Inductively Coupled Plasma Mass Spectrometry For Detecting Low-Level Lead In Child Whole Blood Samples, Christina Sobin, Tanner Schaub, Natali Parisi, Eva De La Riva

Christina Sobin, Ph.D.

Chronic childhood lead exposure, yielding blood lead levels consistently below 10 μg/dL, remains a major public health concern. Low neurotoxic effect thresholds have not yet been established. Progress requires accurate, efficient, and cost-effective methods for testing large numbers of children. The LeadCare® System (LCS) may provide one ready option. The comparability of this system to the “gold standard” method of inductively coupled plasma mass spectrometry (ICP-MS) for the purpose of detecting blood lead levels below 10 μg/dL has not yet been examined. Paired blood samples from 177 children ages 5.2–12.8 years were tested with LCS and ICP-MS. Triplicate repeat tests …

The Analysis Of Cyanide And Its Breakdown Products In Biological Samples, Brian A. Logue, Diane M. Hinkens, Steven I. Baskin, Gary A. Rockwood

Chemistry and Biochemistry Faculty Publications

Cyanide is a toxic chemical that may be introduced into living organisms as a result of natural processes and/or anthropogenic uses (legal or illicit). Exposure to cyanide can be verified by analysis of cyanide or one of its breakdown products from biological samples. This verification may be important for medical, law-enforcement, military, forensic, research, or veterinary purposes. This review will discuss current bioanalytical techniques used for the verification of cyanide exposure, identify common problems associated with the analysis of cyanide and its biological breakdown products, and briefly address the metabolism and toxicokinetics of cyanide and its breakdown products in biological …

Sulfur K-Edge Photo-Fragmentation Of Ethylene Sulfide, Wayne C. Stolte, Gunnar Ohrwall

Chemistry and Biochemistry Faculty Publications

We have investigated the photofragmentation properties of the three-membered ring heterocyclic molecule ethylene sulfide or thiirane, C₂H₄S, by time-of-flight mass spectroscopy. Positive ions have been collected as a function of photon energy around the S K ionization threshold. Branching ratios were derived for all detected ions, which are informative of the decay dynamics and photofragmentation patterns of the core-excited species. We present a new assignment of the spectral features around the S K-edge.

Iron And Manganese Based Nanomaterials For The Removal Of Selenite And Selenate From Aqueous Solution, Christina Marie Gonzalez

Open Access Theses & Dissertations

Selenium, a naturally occurring element in the environment, is an essential nutrient for humans and animals. However, there is a narrow range between selenium deficiency and toxicity. Selenium in natural waters generally has a concentration of < 10 ppb (parts per billion); however, in the San Joaquin Valley of California concentrations of selenium ranging from 140 to 1400 ppb have been observed. Anthropogenic practices such as agricultural irrigation drainage, coal burning power plants, combustion of fossil fuels, and mining operations are increasing selenium concentrations in aqueous environments. Once in aqueous environments, selenium exists primarily as the two inorganic oxoanions selenite (SeO32-) and selenate (SeO42-). Both of these selenium oxoanions are known to bioaccumulate and can cause embryotoxic and teratogenic effects to waterfowl. There has been a variety of treatment technologies developed for remediation of both selenium oxoanions in water including bacterial reduction, membrane filtration, chemical reduction, reverse osmosis, and solar ponds. However, these treatment technologies are not cost efficient. In this study an alternative treatment technique known as adsorption was used with three synthetic nanomaterials consisting of an iron oxide, manganese oxide, and an iron/manganese oxide. The pH profiles, time dependencies, competitive anion effects, and adsorption isotherms were performed with each of the nanomaterials for both selenite and selenate. In addition, X-ray absorption spectroscopy (XAS) studies were performed to determine both the oxidation state and binding coordination of the selenium oxoanion binding to the nanomaterials.

The investigation revealed the non microwave-assisted and microwave-assisted synthetic Fe3O4 and Mn3O4 nanomaterials, as well as the non microwave-assisted synthetic MnFe2O4 nanomaterial had the phases of magnetite, hausmannite, and Jacobsite, while the grain sizes were 27, 25, 25, 34, and 27 nm, respectively. The optimal binding of selenium oxoanions for all nanomaterials examined was reached at pH 4. Both non microwave-assisted and microwave-assisted Fe3O4 …

Transition States In Ei Reactions, Charles A. Kingsbury

Faculty Publications -- Chemistry Department

The pyrolysis of amine oxides, sulfoxides, selenoxides, and esters to form alkenes is believed to be a concerted reaction with a cyclic transition state. Phosphine oxides, sulfones, and nitro compounds are unreactive. This study seeks to identify reasons for the lack of reactivity of the latter. Transition states were located for all substrates progressing from RHF/3-21G* to the MP2/6-31+G(d,p) level (in certain cases). For sulfones and nitro compounds, two possible reasons for lack of reactivity were considered: (1) Atoms approaching one another in the transition state may be considered to participate in a local n_O→σ*_{CH …}

Self-Assembled Heteroleptic Chiral Ligands, Asymmetric Catalyst Systems And Methods, James M. Takacs

Faculty Publications -- Chemistry Department

A method of synthesizing a heteroleptic, multiple metal containing metallocyclic catalyst, particularly Suited for asymmetric catalysis, comprising combining a plurality of plural functional group-containing, monodentate ligands of complementary chirality, said plural functional groups being tethered to each other by tethers in the presence of a scaffold structural metal Ms or derivative thereof, wherein at least one functional group on each ligand combines to ligate M to form a bidentate, M_s centered ligand scaffold containing the remaining functional groups and combining said bidentate ligand scaffold with a catalytic metal M_c or derivative thereof whereby the remaining functional groups combine …