Analytical Chemistry Commons^™

Comparison Of Atmospheric Pressure Chemical Ionization And Electrospray Ionization Mass Spectrometry For The Direct Analysis Of Hops Bittering Compounds, Chhiring Sherpa

Masters Theses

Hops acids are essential components in the beer brewing process containing alpha acids (α-acids) and beta acids (β-acids) as the major hops bittering compounds. Quantifying these acids is vital for quality control and determining bitterness levels and hops variety profiles. Current industry standards, like High-Performance Liquid Chromatography with Ultraviolet detection (HPLC-UV) and Ultraviolet Spectroscopy (UV-Vis), though effective, are time-consuming and solvent-intensive, providing incomplete information.

This research introduces a novel method using mass spectrometry with atmospheric pressure chemical ionization (APCI-MS) to analyze hops bittering acids without chromatographic separations. This approach offers rapid analysis, high throughput, and eco-friendliness.

Comparison with direct electrospray …

Diagnosing Discharge Events Within A Novel Miniature Simplified Coaxial Ion Trap Mass Analyzer, David Virgil Sirbescu-Stanley

Masters Theses

Mass spectrometry is a technique that organizes material samples by mass to reveal their chemical composition by forming a spectrum. Since their invention, ion trap mass spectrometers have undergone significant enhancements. This work, funded by the National Science Foundation and in collaboration with Brigham Young University, the Simplified Coaxial Ion Trap (SCIT), attempts to simplify ion trap geometry and combine three ion traps into one device. Successful demonstration of the SCIT functionality could reduce costs, reduce manufacturing complexity, and shrink total instrument volume. At the same time, trapping capacity and analytical efficiency will be increased. However, as discussed within, challenges …

Development Of A Chemical Biology Approach To Uncover The Influence Of Sequence Variations On Ces1 Activity In Live Cells, Samuel James Knebel

Masters Theses

Drug metabolism is the biochemical process of modifying drugs to detoxify and remove them through enzymatic transformations. These biotransformation’s occur primarily in the liver and are critical to understanding how pharmaceutical compounds are chemically altered inside the human body. Human carboxylesterases (CESs) catalyze the hydrolysis of esters, amides, thioesters, and carbamates. CES-mediated hydrolysis plays an important role in the metabolism of many drugs including the first FDA approved antiviral treatment for COVID-19, remdesivir (Veklury), the seizure control medication rufinamide (Banzel), and the flu antiviral drug oseltamivir (Tamiflu). CES activity is known to be influenced by a variety of factors including …

Interfacial Electrochemistry In Metallic Film Fabrication, Eric S. Tuala

Masters Theses

An experimental determination of RC constant at the edge and the center of a disk electrode was done using in situ reflectance spectroscopy on a Au electrode immersed in HClO₄ as electrolyte. The RC constant at the edge of the disk electrode was found much smaller than that at the center. Such differences contribute to the selective removal of the deposited Cu on an Au disk electrode.

Furthermore, the electrochemical corrosion of Cu²⁺ towards Co electrode (called cementation reaction) was investigated using a Co/Pt rotating disk electrode. The Open Circuit Potential of Co electrode in CuSO₄ electrolyte …

Synthesis, Characterization And Mechanistic Studies Of Biomimetic Dinuclear Copper(Ii) Complexes, Millaniyage Nuwanthaka Prasad Jayaweera

Masters Theses

Dinuclear copper complexes are significant synthetic targets due to their use as model compounds for the active sites of type 3 copper proteins like catechol oxidase. A distinct class of ligands used in these studies are built on a phenol core to witch various donor side-arms were appended at the 2 and 6 positions of the arene ring. In our quest to quantify the influence of electron donating or withdrawing groups attached to the central arene ring, we have designed a set of ligands that, upon coordination to copper(II) centers, would produce complexes of the general structure. During this research …

Studying Carbon Dioxide Solvent Properties By Microwave Spectroscopic Investigations Of Vinyl Fluoride/Carbon Dioxide Clusters And Developing New Approaches To Decode Rotational Spectra, Prashansa Kannangara

Masters Theses

Supercritical carbon dioxide (sc-C0₂) is an excellent green solvent, but its properties are not thoroughly understood. For example, fluorinated compounds have higher than expected solubility in sc-C0₂. Microwave spectroscopy is one way to learn more about sc-C0₂ because it can be used to determine detailed structures of small clusters of molecules. The purpose of this investigation was to study weak hydrogen bonding interactions in complexes of fluorinated ethylene (solute) with carbon dioxide (C0₂, solvent). Investigations on dimers with one C0₂ molecule and fluorinated ethylene were carried out previously and found two different …

Solvation Properites Of Supercritical Carbon Dioxide Using Chirped-Pulse Fourier-Transform Microwave Spectra Of Carbon Dioxide / 1, 1-Difluoroethene (Dfe) Mixtures, Tulana Ariyaratne Subasinghe Arachchige

Masters Theses

Supercritical carbon dioxide (sc-C0₂) is a highly utilized industrial substance identified as an excellent solvent and a surfactant, which is cheaper and less hazardous than other typical solvents. The higher solubility of fluorinated hydrocarbons than their hydrocarbon (HC) analogs is not well understood and the theory behind the microsolvation of sc-C0₂ cannot be fully explained with the existing chemical information. Microwave spectroscopy is a good method of identifying the structural arrangement of clusters made from fluorinated HCs and C0₂. I n this project, microwave scans of the four different mixtures of 1 , 1-difluoroethene (DFE) …

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 …

Derivatization And Separation Of Natural Estrogens (Estrone, 17Β-Estradiol, And Estriol) Using Gas Chromatography With Flame Ionization Detection (Gc-Fid), Dena L. Guptill

Masters Theses

A major cause of concern for estrogens found in the environment is that even at very low concentrations (10-100 ng/L) they can have a negative effect on aquatic ecosystems by disrupting endocrine systems. Due to the increasing importance of monitoring the levels of estrogens in the environment, a detection method was developed to identify and quantify three natural estrogens (estrone, 17β-estradiol and estriol) using gas chromatography with flame ionization detection (GC-FID). In addition, the efficacy of two derivatizing agents, N,O-bis(trimethylsilyl) acetamide (BSTA) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), was evaluated. The GC detector (FID) was most responsive with E3, followed by E1 and …

Reactions Of Modified Silica Gel Surfaces With Organometallic Compounds: Enhancing Olefin Polymerization Catalysts, Richard E. Diebel Iii

Masters Theses

Pretreated silica gels with distinct silica surfaces containing either isolated silanols, vicinal silanols, siloxanes, or some combinations of the three, were reacted with several organometallic compounds to determine how each compound reacted with the different silica surface species. The organometallic compounds used were trimethylaluminum, triethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, methylaluminoxane, dibutylmagnesium, and bis-cyclopentadienyl dimethyl zirconium.

These reacted silica gels were analyzed using diffuse reflectance infrared Fourier transform spectroscopy and ICP-AES elemental analysis. CH/Metal ratios were calculated using specific peaks in the IR spectra to elucidate the surface bonded species. Elemental analysis was used to determine how much metal was bonded …

An Analysis Of Dissolved Organic Compounds And Their Contribution To Iron Complexation In The Shallow Leachate Plume Of The West Kl Landfill Kalamazoo, Michigan, Eric Fahle

Masters Theses

High concentrations of dissolved iron are present in downgradient groundwater samples adjacent to the western border of the West KL Landfill. Analysis by Rudder (1988) of groundwater samples indicates oversaturation of selected iron oxides, iron sulfides and siderite in monitoring wells TW-4 and M3.

Previous research suggests that pyrogallol, gallic acid, tannic acid and similar organic compounds may retard the oxidation of ferrous iron in the shallow leachate plume of the West KL landfill (Rudder, 1988). Present research utilizing solid phase extraction, reverse phase high performance chromatography, Fourier transform IR spectrophotometry, UV/Visible spectrophotometry, and gas chromatography/mass spectroscopy indicate that pyrogallol, …

Kinetics Of The Metal-Exchange Reaction Between Ortho-Phospho-Dl -Serinenickelate(Ii) And Copper(Ii), Jeffrey M. Peterman

Masters Theses

No abstract provided.

Characterization Of The Lipopolysaccharides From Rhizobium Phaseoli Symbiotic Mutants, Francisca Garcia

Masters Theses

The lipopolysaccharides (LPSs) of the Rhizobium phaseoli CE3 and its mutants CE109, CE309 and the transconjugate Rhizobium leguminosarum LB2/109.11 were isolated and analyzed by gas chromatography (GC) and ¹H nuclear magnetic resonance (NMR) spectroscopy. CE3 is the wild type strain which is nodulation-proficient (Nod⁺). Strain CE109 and CE309 have a transposon, Tn5, inserted into Region I and Region III of their respetive chromosomes. Mutants CE109 and CE309 are defective in nodule development (Ndv^-). Transconjugate R. leg. LB2/109.11 has the DNA of the R. leg. LB2 wild type and also Region I portion of the CE109 …

Kinetics Of The Metal-Exchange Reaction Between N-(2-Pyridylmethyl)Iminodiacetatonickel(N) And Copper(Ii), Kassahun W. Beyene

Masters Theses

The reaction between N-(2-pyridylmethyl)iminodiacetatonickel(II) and copper(II) was studied spectrophotometrically between pH 2.30 and 3.30 over a 10-fold variation in copper concentration at an ionic strength of 1.25M, and a temperature of 25.0+0.1^oC. The reaction is first order in both NiPyIDA and copper(II). Terms involving proton attack and a copper dependent dissociation of the nickel complex were resolved from the data. Evidence is given for a stepwise unwrapping mechanism PyIDA from the nickel complex, followed by copper attack to give a dinuclear intermediate. A general mechanism is presented which is consistent with the kinetic data.

Comparisons to analogous nickel-aliphatic …

High Performance Liquid Chromatographic Determination Of Thromboxane B2 In Human Serum As A Methoxime-Panacyl Ester Derivative, Robert H. Pullen

Masters Theses

No abstract provided.

Reactive Counterion Surfactant Catalysis Of Hydroxamic Acid Hydrolysis With Perfluorooctanoic Acid, Mohamed El-Sayed Ayoub

Masters Theses

A micellar effect upon the rate of hydrolysis of hydroxamic acids in aqueous perfluorooctanoic acid has been demonstrated for hydroxamic acids with chain lengths of six , eight, and ten carbons. In this system the counterion, hydrogenion, is a catalyst. Typical rate constant-surfactant concentration profiles for micellar catalysis were obtained. The results for these hydrolyses are consistent with the pseudo-phase model for micellar effects.

In addition the Arrhenius activation energies were determined for the reaction of octanohydroxamic acid at surfactant concentrations above and below the critical micelle concentration of the surfactant. The activation energy is lower for reaction in the …

The Purification And Partial Characterization Of The Surface Polysaccharides From Three Fast-Growing Rhizobium Japonicum Strains, Madhav P. Yadav

Masters Theses

The fast-growing strains of R. japonicum were originally isolated from China. They are acid-producing Rhizobia and are capable of nodulating soybeans. These isolates share a common host-specificity (Peking soybean) with the slow-growing R. japonicum strains even though their biochemical properties are more closely related to other fast-growing Rhizobium species. The surface polysaccharides from three fast-growing R. japonicum strains--USDA201, USDA205, and HC205--were isolated and partially characterized. Strain HC205 is a nod⁻ mutant of USDA205 which lacks the symbiotic plasmid. These surface polysaccharides consist of extracellular, capsular and lipopolysaccharides (EPSs, CPSs and LPSs). The EPSs from all three strains are very similar …

A Microprocessor Controlled Pulsed Hollow Cathode Lamp For An Atomic Absorption Spectrometer, James B. Schilling

Masters Theses

A Jarrell-Ash Atomic Absorption/Flame Emission 82-360 Spectrometer was interfaced to a Heathkit ETA-3400 microprocessor. The microprocessor is used to pulse the hollow cathode lamp from a "steady" current to a "peak " current during the opening of the chopper. The current from the photomultiplier-tube is converted to a proportional voltage which is supplied to a sample-and-hold circuit. A successive approximation routine is used to convert the voltage to a representative digital value. Digital values are obtained for the "blank" and "sample" and are used to calculate percent absorption values. The system can also be used to obtain emission values.

The …

Internal Rotation Effects And Nuclear Hyperfine Structure In The Microwave Spectrum Of Propyne-Hf, Roger E. Bumgarner

Masters Theses

The microwave spectrum of the weakly bound propyne-HF/DF complex in the region between 6 and 16 GHz was analyzed. The spectrum was characteristic of a distorted T-shaped asymmetric top exhibiting torsional splitting caused by a low barrier to internal rotation of the methyl top relative to the propyne-HF frame. Deuterium substitution of HF confirms that the acid proton of HF is located between the F atom and the propyne triple bond. The spectroscopic constants given below are consistent with the fluorine atom being displaced toward the methyl group from a line perpendicular to and bisecting the propyne triple bond, suggesting …

A Column For The High Pressure Liquid Chromatography Of Some Potentially Hazardous Metal Ions, Stephen R. Friebe

Masters Theses

No abstract provided.

Analysis Of Mixtures Of Chlorine, Chlorine Dioxide And Chlorite, Ying-Chien Chu

Masters Theses

No abstract provided.

Photon Counting System For The Determination Of Creatine Phosphokinase, Steven E. Dueball

Masters Theses

No abstract provided.

The Analysis Of N-Methylscopolamine Bromide By High Speed Ion Pair Partition Chromatography, John L. Nappier

Masters Theses

No abstract provided.

The Response Of The Micro-Adsorption Detector To Inorganic Anions, Maria E. Munera

Masters Theses

No abstract provided.

Spectroscopic Studies Of The Hydrogen-Chlorine Flame, Gonzalo Pizarro

Masters Theses

No abstract provided.

Kinetics Of The Formation Of Nickel(Ii) Complexes With N,N’-Dibenzylethylenediamine And N,N’-Bis(2-Picolyl)Ethylenediamine, Zahid Amjad

Masters Theses

No abstract provided.

The Response Of The Micro-Adsorption Detector To Inorganic Cations, David P. Mckay

Masters Theses

No abstract provided.

The Design, Construction, And Application Of A Multibeam Fiber Optics Photometric Titrator, Marlin George Bensinger

Masters Theses

No abstract provided.

The Stepwise Nature Of The Unwrapping And Transfer Of Ethylenediaminediacetate From Nickel(Ii) To Copper(Ii), Robert Swann

Masters Theses

No abstract provided.

Fluorescence Studies Of Cobalt (Iii) Complexes, Arnold T. Weibel

Masters Theses

No abstract provided.