Analytical Chemistry Commons^™

Arsenic Speciation Analysis Of Biological Fluids : A Study Of Liquid Chromatography Coupled To Analytical Atomic Spectrometric Instrumentation, Kanna Ito

Legacy Theses & Dissertations (2009 - 2024)

Arsenic exists as many different chemical forms including inorganic, methylated and dietary species. The toxicity of these species varies: some are highly toxic and can cause adverse health effects in many parts of the body; others are considered relatively non-toxic. Monitoring arsenic exposure is usually accomplished by its direct measurement in biological fluids. Urine is the specimen of choice for assessing arsenic exposure, because of its short biological half-life in blood. There have been very few studies of arsenic species in blood, yet such research can provide valuable information on arsenic distribution and its metabolism in the body.

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

Department of Chemistry: Faculty Publications

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 …

Corrosion Of Steel Shipwrecks In The Marine Environment: Uss Arizona—Part 2, Donald L. Johnson, Brent M. Wilson, James D. Carr, Matthew A. Russell, Larry E. Murphy, David L. Conlin

Department of Chemistry: Faculty Publications

This article is a continuation of Part 1 (October 2006 MP) on the USS Arizona hull. It discusses additional methods being investigated for use in determining corrosion rates with a minimal impact on the existing structure. Marine biofouling (concretion) has accumulated on the hull. Concretion samples have been studied using x-ray diffraction, environmental electron microscopy, and corrosion potential (E_corr) to characterize the relationship between concretion and the steel substrate. The data presented in this study confirm the viability of concretion analysis as a minimum-impact procedure to estimate the corrosion rate of mild steel in seawater.

Corrosion Of Steel Shipwreck In The Marine Environment: Uss Arizona—Part 1, Donald L. Johnson, Brent M. Wilson, James D. Carr, Matthew A. Russell, Larry E. Murphy, David L. Conlin

Department of Chemistry: Faculty Publications

The USS Arizona has remained submerged in Pearl Harbor, Hawaii, since the Japanese attack on December 7, 1941. The ship presents a potential hazard from fuel oil still present in the ship’s hull. As an important factor in management decisions, the effect of corrosion after nearly 65 years is being studied to determine the integrity of the ship’s structure. Coupon samples from the hull revealed decreasing corrosion rates from ~1 to 3 mpy (0.03 to 0.08 mm/y) from just below the water surface to the mudline. This is about one-third of that expected in the absence of biofouling or concretion. …

Method For Monitoring The Stereoselectivity And Relative Rate Of Organic Chemical Reactions, David R. Berkowitz, Sangeeta Dey, Kannan R. Karukurichi, Weijun Shen

Department of Chemistry: Faculty Publications

A method for monitoring the stereoselectivity of at least one organic chemical reaction and the relative rate of at least one organic chemical reaction, wherein the reaction produces a product that can exist as at least two stereoisomers, is provided herein. Also disclosed are methods for identifying and preparing catalysts for the above reactions.

Supramolecular Self-Assembly Strategies Involving Water Soluble Calixarenes., Irene Ling

Student Works (2010-2019)

Fundamental investigations of host-guest interactions on the supramolecular self-assembly involving water-soluble p-sulfonatocalix[4]arene, with a series of imidazolium-based cations and pyrrolidinium cation with variable alkyl chain lengths, which featured extensively in ionic liquids have been established. Combinatorial studies incorporating multiple components concerning p-sulfonatocalix[4]arene, imidazolium cations or pyrrolidinium cation, phosphonium cations and lanthanide ions have been developed, which yielded diverse solid state motifs with a common structural characteristic that the imidazolium or pyrrolidinium cation resides in the cavity of the calixarene. Shorter terminal alkyl chain of mono-imidazolium molecules, i.e. n-ethyl and n-butyl imidazoliums are confined in the „molecular capsule‟, being encapsulated by …

Toxicodynamics And Biotransformation Of Azaspiracids Incorporating Liquid Chromatography-Tandem-Mass Spectrometry (Lc-Ms/Ms) Techniques., Daniel O'Driscoll

Theses

Azaspiracids (AZAs) are a family of lipophilic polyether marine biotoxins, that have caused a number of human intoxication incidents in Europe since 1995, which was the first incident reported following the consumption by consumers of intoxicated shellfish {Mytilus edulis). This class of phycotoxins has been responsible for extended closures of shellfisheries in various locations around Europe, where levels of AZAl-3 are regulated in shellfish. Since their discovery in 1995, AZAs have become the focus of extensive research, resulting in the discovery of numerous analogues. Only AZAl and AZA2 have been found in phytoplankton and all the other analogues are believed …

Application Of Liquid Chromatography - Tandem Mass Spectrometry For The Determination Of Veterinary Drug Residues In Food Of Animal Origin, Brian Kinsella

Theses

The QuEChERS (quick, easy, cheap, effective, rugged and safe) sample preparation approach was evaluated for the extraction of anthelmintic residues from bovine milk and tissues. Liquid chromatography coupled to tandem mass spectrom.etry (LC- MS/MS) was used for detection and quantification of residues, which included the benzimidazoles (BZs), macrocyclic lactones (MLS) and the generally overlooked flukicides.

Initial work focused on the optimisation of a QuEChERS method to effectively extract anthelmintic residues from milk and liver. The method involves the extraction of residues with acetonitrile (MeCN) in the presence of salts (MgS04 and NaCl) to induce phase separation. After shaking and centrifugation, …

A New Green Chemistry Method Based On Plant Extracts To Synthesize Gold Nanoparticles, Milka Odemariz Montes Castillo

Open Access Theses & Dissertations

Extraordinary chemical and physical properties exhibited by nanomaterials, as compared to their bulk counterparts, have made the area of nanotechnology a growing realm in the past three decades. It is the nanoscale size (from 1 to 100 nm) and the morphologies of nanomaterials that provide several properties and applications not possible for the same material in the bulk. Magnetic and optical properties, as well as surface reactivity are highly dependent on the size and morphology of the nanomaterial. Diverse nanomaterials are being widely used in molecular diagnostics as well as in medicine, electronic and optical devices. Among the most studied …

Study Of Pbdes In Wastewater, Water And Sludge Of El Paso Del Norte Border Region Using Sbse Td/Gc-Ms, Beatriz Adriana Rocha-Gutierrez

Open Access Theses & Dissertations

Polybrominated diphenyl ethers (PBDEs) are a group of brominated compounds widely used as flame retardants. PBDEs are structurally similar to polychlorinated biphenyls (PCBs), and appear to act similarly in the environment. Due to their persistence and lipophilicity, PBDEs are found to be bioaccumulated and biomagnified in the food chain. Current research in PBDEs is focused on their occurrences, concentration, fate and transport in the environment, and the impact in the ecosystem and human health. Since PBDEs are not regulated in the USA, large amounts of these harmful chemicals are being dumped indiscriminately into the drainage system. As a result, these …

Application Of Solid-Phase Microextraction For The Analysis Of Polycyclic Aromatic Hydrocarbons In Hyophila Involuta As A Natural Biosensor., Elizabeth Fong Yew Mei

Student Works (2010-2019)

This work describes a simple and rapid extraction method by using solid-phase microextraction (SPME) technique for the determination of polycyclic aromatic hydrocarbons (PAHs) from mosses of Hyophila involuta which is found commonly and abundantly throughout Peninsular Malaysia. Mosses have been chosen in our study since they are effective bioindicators as they take up nutrients and pollutants directly from the atmosphere and they have no root system. These properties make them ideal for evaluating pollutant levels in the air over a monitored period of time. This study has been developed and optimized based on the extraction of the analytes of interest …

Studies Of Antioxidant Activity Of Bioactive Compounds Derived From Ardisia Crispa., Hassan Mahmood Kzar Jindal

Student Works (2010-2019)

In recent times, researches have focused on medicinal plants in order to extract natural and low cost antioxidants that can help protect the human body against oxidative stress, and replace the synthetic additives that might be carcinogenic. In present study, the crude extracts of leaves and fruits from Ardisia crispa were investigated for their chemical constituents and antioxidant activity. Preliminary phytochemical screening of the crude extracts via TLC analysis revealed the presence of several secondary compounds mainly, terpenoids and phenolic compounds in addition to alkaloids and saponins. HPLC analysis showed the possibility of presence of gallic acid in the fruits …

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 …

Chromium(Iii/Vi) Binding To Magnetite (Fe3o4), Hausmannite (Mn3o4), And Jacobsite (Mnfe2o4) Nanomaterials, Jeffrey Edward Hernandez

Open Access Theses & Dissertations

Chromium is a very versatile metal that is used for many applications in the world. Two of the most common ions of chromium that occur naturally are Cr(III) and Cr(VI). These two oxidation states have very different heath effects in living organisms. Cr(III) is relatively non-toxic to living organisms; however, Cr(VI) is very toxic to most living organisms This study was conducted to find a simple and cost effective method to sequester these two common ionic species of chromium from sources of water that are adjacent to or that are affected by other water sources contaminated by these two ions. …

Optimization Of Solid-Phase Microextraction For The Determination Of Organo-Phosphorus And Organo-Chlorine Pesticide Residues In Natural Water Near Aquaculture Farms., Chan Chun Foong

Student Works (2010-2019)

The global shrimp farming industry had a rapid growth in the 1980s due to the high demand for shrimp. Apart from the destruction of mangroves and wetlands, the intensive operation of shrimp aquaculture deteriorated the water quality in the region. Variety of chemicals and biological products were used to prevent the outbreaks of diseases in the intensively managed shrimp ponds. Pesticides were used as disinfectands to kill unwanted organisms in the pond. SPME-GC-ECD method was developed for the determination of azinphos-ethyl, chlorphyrifos-methyl, diazinon, dichlorvos, endosulfan-I, endosulfan-II, endosulfan sulfate and malathion from water samples of shrimp aquaculture area in Manjung district, …

Synthesis, Characterization And Electrochemical Studies Of Cu(Ii), Fe(Ii), Fe(Iii) And Ni(Ii) Complexes Of Someo-Phenylenediamine Schiff Bases., Abdulaziz Ali Alomari

Student Works (2010-2019)

Four Schiff base ligands, N,N’-1,2-benzene-1,2-diyl-bis(5-chlorosalicylideneimine) (H2L1), N,N’-1,2-benzene-1,2-diyl-bis(4-bromosalicylideneimine) (H2L2), N,N’-1,2- benzene-1,2-diyl-bis(4-hydroxysalicylideneimine) (H2L3), and N,N’-1,2-benzene-1,2-diyl-bis(3-bromo-5-chlorosalicylideneimine) (H2L4) were obtained in good yields from the condensation reaction of o-phenylenediamine with 5-chlorosalicylaldehyde, 5-bromosalicylaldehyde, 4-hydroxysalicylaldehyde and 3-bromo-5-chlorosalicylaldehyde respectively. These Schiff bases formed complexes with copper(II), iron(II) and nickel(II) ions in good yields. The structures of these complexes are mainly square planar, which is confirmed by the crystal structure of nickel(II) complex of bis-N,N’-3-chloro-5-bromosalicylideneamine-,2-diaminobenzene. Attempts to prepare the corresponding iron(III) complexes were unsuccessful. The ligands were characterized by Fourier transform infrared spectroscopy, elemental analysis, 1H-Nuclear magnetic resonance spectroscopy and UV-vis spectroscopy, while the complexes were characterized by …

Explorations In Homeoviscous Adaptation And Mass Spectral Analysis Of Membrane Lipids, Michael Douglas Timmons

University of Kentucky Doctoral Dissertations

The focus of this dissertation is centered on the mass spectral analysis of lipids and changes occurring in keeping with the concept of homeoviscous adaptation [1]. Homeoviscous adaptation is the process of modification of membrane lipids in response to environmental stimuli [1]. Dissertation investigations applied this concept to prokaryotic and eukaryotic organisms, and expanded the perception of environmental factors from exogenous organic solvents to intracellular environment.

The field of lipidomics deals with the analysis of phospholipid and fatty acid components of membranes the changes that occur due to environmental stimuli and their biological significance [2-6]. The high sensitivity of mass …

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

Chemistry and Biochemistry Faculty Research

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.