Analytical Chemistry Commons^™

Classification And Cluster Analysis Of Complex Time-Of-Flight Secondary Ion Mass Spectrometry For Biological Samples, Stephen E. Reichenbach, Xue Tian, Qingping Tao, Alex Henderson

Steve Reichenbach

Identifying and separating subtly different biological samples is one of the most critical tasks in biological analysis. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is becoming a popular and important technique in the analysis of biological samples, because it can detect molecular information and characterize chemical composition. ToF-SIMS spectra of biological samples are enormously complex with large mass ranges and many peaks. As a result the classification and cluster analysis are challenging. This study presents a new classification algorithm, the most similar neighbor with a probability-based spectrum similarity measure (MSN- PSSM), which uses all the information in the entire ToF- SIMS …

Hydrogen Exchange Mass Spectrometry For Studying Protein-Ligand Interactions, Modupeola A. Sowole

Electronic Thesis and Dissertation Repository

Hydrogen deuterium exchange (HDX) coupled with mass spectrometry is widely used for probing protein structure and dynamics. Protein-ligand interactions usually induce a reduction in the measured HDX rates an effect that may be ascribed to stabilization of the protein structure. This work aims to improve the general understanding of the changes in HDX patterns associated with ligand binding.

We initially applied HDX for studying differences between oxy-hemoglobin (Oxy-Hb) and aquomet-hemoglobin (Chapter 2). The results show that the α and β subunits respond differently to the oxy to aquomet transition with the heme binding pocket being destabilized in both cases. The …

Impurity Diffusion As A Possible Metal Chronometer For Pre-Detonation Nuclear Forensics, Edward T. Peskie, Howard L. Hall

International Journal of Nuclear Security

The ability to determine the age of seized nuclear material—that is, the time that has passed since it was formed— would provide crucial data to be used in its investigation. This paper reviews the methods and mathematical reasoning behind the use of diffusion theory, as previously applied to analysis of metals in ancient artifacts and other objects, to modern investigations in nuclear science. We here examine the time-dependent processes of diffusion, including grain boundary diffusion and discontinuous precipitation, and we assess the utility of examining the profiles of impurity and alloying element concentrations for use as a tool in pre-detonation …

Mangiferin As A Biomarker For Mango Anthracnose Resistance, Herma Pierre

FIU Electronic Theses and Dissertations

Mangos (Mangifera indica L.) are tropical/subtropical fruits belonging to the plant family Anacardiaceae. Anthracnose is the most deleterious disease of mango both in the field and during postharvest handling. It is most commonly caused by the Colletotrichum gloeosporioides complex. Mangiferin, a xanthanoid compound found in at least twelve plant families worldwide (Luo et al., 2012), is present in large amounts of the leaves and edible mangos. Even though this compound plays a pivotal role in the plant’s defense against biotic and abiotic stressors, no correlations been made between the compound and mango anthracnose resistance.

Mangos were collected, grouped …

Determining % Proliss 100 In Keratin Mousse Using Iodine Solution Method, Quiana Moore

All Capstone Projects

The objective of this experiment is to quantitatively determine the amount of active raw material Proliss 100 manufactured and supplied by a formulation company. The goal is to reproduce the percent of Proliss in Keratin Mousse production sample provided to consumers and provide measurements to be used to assess the accuracy of production with comparison to provided percent formulation for each batch. An iodine solution titration method was performed for this experiment due to the reduction-oxidation reactivity of the Proliss 100. This experiment is still undergoing further testing due to the confidentiality agreement between the manufacturer and formulator.

In Vitro Microdialysis Sampling Collection Of Volatile Organic Compounds (Voc's), Dodecafluoropentane (Ddfp) And Isoflurane, Valerie Shannon Mckinney

Graduate Theses and Dissertations

Death by stroke occurs every four minutes to human beings. Strokes cause necrosis within the tissue of the brain due to deprivation of oxygen. Perfluorocarbons have the ability to transport oxygen to tissue and in return decrease cell death. Dodecafluoropentane (DDFP) is a volatile fluorocarbon and collection in vivo can be a challenge since this compound evaporates at room temperature. There is currently not an efficient collection method in vivo for compounds that are volatile. Without a method to collect DDFP it is impossible to be approved for clinical use since exact concentrations of the drug within the body will …

Artificial Maturation Studies Of Polymethylenic Plant Biopolymers: Investigating The Chemical Alterations From Plant Material To Coal, Blaine Elizabeth Hartman

Chemistry & Biochemistry Theses & Dissertations

The thermal maturation and alternation of vascular plant material into coals and as expelled petroleum-like compounds is the main focus of this dissertation. Utilizing artificial maturation studies, like hydrothermal liquefaction, yields useful information regarding how plant material is preserved in coals and the potential certain plant biopolymers possess to generate liquid fuels is acquired. The studies within this dissertation focus on utilizing the aliphatic biopolymers, cutin, cutan, and suberan, found in the epidermis of certain plants. These biopolymers contain minimal amounts of heteroatoms and are comprised of long polymethylenic chains, which are desirable characteristics in generating bio-oils. Additionally, understanding the …

Fundamental Studies Of Magnetoconvective Forces And Density Gradients In A Microfluidic Environment, Adam James Kreidermacher

Graduate Theses and Dissertations

Magnetoconvection is a promising phenomenon for developing new electrochemical-based microfluidic flow devices with unique capabilities, such as easily switching flow direction and adjusting flow speeds and flow patterns as well as avoiding bubble formation. In order to develop these devices it is necessary to study the underlying forces. Four contributions toward fluid flow were considered. The first and foremost is the magnetohydrodynamic force, which is the magnetic component of the Lorentz force and governed by the right hand rule. It generates the majority of the convention, and is the most well-known. The second is the gravitational force, which causes convection …

Target And Non-Target Techniques For The Quantitation Of Drugs Of Abuse, Identification Of Transformation Products, And Characterization Of Contaminants Of Emergent Concern By High Resolution Mass Spectrometry, Nubia Vanesa Heuett

FIU Electronic Theses and Dissertations

Development and application of target and non-target techniques for routine analysis, identification of transformation products, and characterization of unknown compounds in water matrices using liquid-chromatography high-resolution mass spectrometry (HRMS) were explored in this dissertation. A novel analytical method based on online-SPE-LC-HRMS was developed for the detection of 18 drugs of abuse (DOAs) in raw sewage water from a college campus. Results showed the presence of 14 DOAs for which amphetamine and 11-nor-9-carcoxy-THC (THC metabolite) were the most prevalent and had the highest potential consumption rates.

A second study dedicated to the identification of transformation products (TPs) generated from DOAs was …

Using Ion Mobility Spectrometry To Study Protein Conformations In The Gas Phase, Yu Sun

Electronic Thesis and Dissertation Repository

The question whether electrosprayed protein ions retain solution-like conformations remains a matter of debate. One way to address this issue involves comparisons of collision cross sections measured by travelling wave ion mobility spectrometry (TWIMS) with the values calculated for model structures. It is often implied that nanoESI is more conducive for the retention of solution structure than regular ESI. Focusing on four different proteins we demonstrated that collision cross section values and collisional unfolding profiles are virtually indistinguishable under both conditions. Calibration can be challenging because differences in the extent of collisional activation for TWIMS and drift tube calibrant data …

The Best Of Both Worlds: Building On The Copus And Rtop Observation Protocols To Easily And Reliably Measure Various Levels Of Reformed Instructional Practice, Travis J. Lund, Matthew Pilarz, Jonathan B. Velasco, Devasmita Chakraverty, Kaitlyn Rosploch, Molly Undersander, Marilyne Stains

Chemistry Department: Faculty Publications

Researchers, university administrators, and faculty members are increasingly interested in measuring and describing instructional practices provided in science, technology, engineering, and mathematics (STEM) courses at the college level. Specifically, there is keen interest in comparing instructional practices between courses, monitoring changes over time, and mapping observed practices to research-based teaching. While increasingly common observation protocols (Reformed Teaching Observation Protocol [RTOP] and Classroom Observation Protocol in Undergraduate STEM [COPUS]) at the postsecondary level help achieve some of these goals, they also suffer from weaknesses that limit their applicability. In this study, we leverage the strengths of these protocols to provide an …

The Investigation Of The Low Temperature Combustion Of Mesitylene And Tert-Amyl Methyl Ether By Synchrotron Photoionization Mass Spectrometry, Martin Yu-Hin Ng

Master's Theses

This thesis describes the combustion experiments performed at the Chemical Dynamics Beamline of the Advanced Light Source (ALS) located at the Lawrence Berkeley National Laboratories (LBNL). The need for renewable fuel sources, the need for the study of their combustion in the contexts of homogenous charge combustion ignition (HCCI) engines can be found in Chapter 1. The components of the experimental set-up used throughout this thesis—time-of-flight mass spectrometer, Excimer laser, vacuum pumps and other components—and the components of ALS responsible in synchrotron radiation generation and processing—the linear accelerator, the booster ring, insertion devices, gas filters and monochromator are explained in …

Nanodiamond Extraction At A Potential Impact Location, Joel Kathan

DePaul Discoveries

Meteoritic or cometary impacts create the temperature and pressure conditions necessary to form nanodiamonds (NDs). The presence of extracted NDs from rocks of the time and locations of extinctions, fires, or known environmental changes are commonly used to confirm that a theorized cosmic impact occurred to trigger those events. Samples were obtained from an archeological site described in the Old Testament of the Bible as having been destroyed by the God of the Old Testament.† To see if the historical description of Biblical events might have been triggered by a cometary impact or explosion, an attempt was made to …

Diol-Mediated Versus Water-Mediated Proton Transfer Reactions, Angela Moses

DePaul Discoveries

The triple-proton-transfer reactions of 8H-1,8-naphthyridin-2-one (8H-naph) have been investigated by employing different ab initio quantum mechanical methods. The proton transfer reactions studied were facilitated through an adjacent 1,3-propanediol molecule or two adjacent water molecules. Identical proton transfer reactions were studied using a model system of 8H-naph to investigate the validity of computational approaches that use model systems to study more complex systems. The solvent effects on the structures were investigated for comparison to the initial gas phase calculations. The potential energy, reaction force, and work profiles were studied along the intrinsic reaction coordinate to monitor the developing proton transfer reactions.

Quechers (Quick, Easy, Cheap, Effective, Rugged, And Safe) Extraction – Gas Chromatography For The Analysis Of Drugs, Michelle L. Schmidt

Seton Hall University Dissertations and Theses (ETDs)

QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) is an extraction technique developed by Anastassiades and co-workers initially for the extraction of veterinary drugs from animal tissue. Since its inception, it was discovered that this method is particularly adept for the extraction of polar and basic compounds, thus the majority of research previously performed using QuEChERS involves the extraction of pesticides from various matrices, especially fruits, vegetables, and other food products. Combining a liquid-liquid extraction (LLE) and a dispersive solid phase extraction (d-SPE) clean up, QuEChERS provides a clean sample for analysis by gas chromatography (GC) or liquid chromatography (LC) …

Monitoring Dissolution Of Nonsteroidal Anti-Inflammatory Drugs Using Infrared Spectroscopy, Julianne Berger

Seton Hall University Dissertations and Theses (ETDs)

A comparison study was conducted to look at the formulation of three brands of naproxen sodium. These brands included Bayer Aleve ®, CVS All Day Pain Relief and Walgreens All Day Pain Relief. The active and inactive ingredients were the same yet the size and shape of the tablets differ among the three brands. S-naproxen was extracted from the tablets and evaluated by GC-MS to determine the purity of naproxen in the tablets. Dissolution was monitored by an IR probe for eight hours while using 0.1M phosphate buffer pH 7.4, 0.05M phosphate buffer pH 4.5 and simulated gastric fluid pH …

Surface-Engineered Magnetic Nanoparticles For Sample Preparation And Analysis Of Proteins And Peptides, Parisa Pirani

University of New Orleans Theses and Dissertations

Sample preparation as an essential step in mass spectrometry-based analysis, plays a critical role in proteomics studies. Magnetic nanoparticles (MNPs) have been widely used in protein and peptide sample preparation due to their magnetic properties, biocompatibility, easy synthesis and surface functionalization. MNPs loaded with analyte or analyte modification reagent can be easily separated from the reaction medium by an externally applied magnetic field. The small size of MNPs provides high analyte loading and extraction capacity. Additionally, MNP can be decorated with different functional groups to achieve selective modification or extraction of analyte. In this study we have utilized silica coated …

Analysis Of Nitrogen And Phosphorus Nutrients In Lake Sediment, Kelsey L. Berrier

Senior Honors Projects, 2010-2019

Analytical methods for the determination of nitrogen and phosphorus nutrients (NO₃-N, NH₄-N and PO₄-P) in sediment were studied with the goal of developing extraction steps compatible with analysis by ion chromatography (IC). Research focused on extractant solution composition, Dionex OnGuard^® sample pretreatment cartridges for salt removal, and chromatographic resolution. Aqueous test samples, lake sediment samples and spiked lake sediment samples were analyzed. Dionex Ag, Ag/H, and H cartridges were studied for the pretreatment step. Silver (Ag) cartridges were found effective in removing >99% of interfering chloride ion to allow NO₃-N determination …

An Investigation Of Inorganic Compound Scattering., Karl Jay Bernstein

Doctoral Dissertations

Raman and its associated forms of spectroscopy are powerful tools that have been under-utilized. Presented within are three inorganic compounds studied with some form of Raman spectroscopy: normal Raman, hyper-Raman (HR), surface-enhanced Raman spectroscopy (SERS), surface-enhanced hyper-Raman spectroscopy (SEHRS), or resonance Raman spectroscopy (RR).

The first study involves the investigation of phosphine binding with silver metal. Phosphines find wide use in synthetic circles yet have had little study into their method of binding, unlike similar compounds comprised of sulfur. In order to understand the binding of phosphines, several tertiary phosphines, secondary phosphines and secondary phosphine oxides are examined with SERS. …

Oxygen Reduction Reaction By Copper Complex Based Electrocatalysts, Congling Zhang

Doctoral Dissertations

My research focuses on catalysis of oxygen reduction reaction (ORR) by a series of Cu(II) [copper with positive two valence] -1,2,4-triazole complex-based electrocatalysts at the cathode of PEMFC (polymer electrolyte membrane fuel cell), an efficient and environmental friendly energy conversion system compared to internal combustion engines in use today. The sluggish kinetics of ORR considerably limited the performance of PEMFCs. Understanding of ORR mechanism is important for developing affordable, active and durable ORR catalysts for such devices.

The first part of my work focused on improving the ORR performance of Cu(II)-1,2,4-triazole complex-based catalysts in an acidic environment by exploring synthesis …