Analytical Chemistry Commons^™

Novel Applications Of Mass Spectrometry For Quantitation And Reaction Mechanism Elucidation, Pengyi Zhao

Dissertations

Mass spectrometry (MS) has been growing as one of the most widely used tools in the field of analytical chemistry. Various applications have been developed to harness the high sensitivity and specificity of mass spectrometric analysis. In this dissertation, two major challenges are addressed. By developing mass spectrometric-based methods, absolute quantitation of proteins/peptides have been achieved. Elucidation of various reaction mechanisms are also enabled. These are the focuses of this dissertation.

In Chapters 2 to 4, a novel quantitation method is developed, titled as coulometric mass spectrometry (CMS). The strength of this method is that no reference standard or isotope-labeled …

Novel Electrochemical Sensor Based On Integration Of Nanoporous Gold With Molecularly Imprinted Polymer For Detection Of Arsenic Ion(Iii), Wu-Wei Ma, Qi-Gang Chang, Xiong-Fang Shi, Yan-Bin Tong, Li Zhou, Bang-Ce Ye, Jian-Jiang Lu, Jin-Hu Zhao

Journal of Electrochemistry

Arsenic, a toxic chemical element, is detrimental to environment and human health in particular. Therefore, the development of simple, fast, and accurate arsenic ion (As³⁺) detection methods has attracted extensive attention. In this work, an electrochemical sensor based on molecular imprinted polymer (MIP) and nano-porous gold (NPG) modified indium tin oxide (ITO) electrode (MIP/NPG/ITO) was developed for determination of As³⁺ in water with different quality. NPG with high conductivity, large specific surface area and high biocompatibility was prepared in situ on ITO surface by a green electrodeposition method using simple and controllable steps. Then, a layer of …

Functionalized Materials From Atom Transfer Radical Processes, Sean Fischer

Electronic Theses and Dissertations

This work is focused on the synthesis, characterization, and application of functionalized materials prepared from atom transfer radical processes. Atom transfer radical processes encompass both atom transfer radical addition (ATRA) and polymerization (ATRP) reactions, both of which are catalyzed by ppm amounts of copper complexes. The synthetic efforts of ATRA include increasing adduct selectivity through optimization of reaction conditions to generate small molecules in high to moderate yields. ATRA provides retention of the halogen moiety, which is an attractive functional group that can be further modified with other transformations. Specifically, the copper-catalyzed azide-alkyne [3+2] cycloaddition (CuAAC) allows for the realization …

Accurate Quantitation Of Hexavalent Chromium For Reference Standard Certification And Quality Control Testing Using Speciated Isotope Dilution Mass Spectrometry, James E. Henderson

Electronic Theses and Dissertations

The ability to perform accurate, repeatable, and defensible elemental and molecular speciated analysis is immensely significant for measurements that support human health, environmental science, and industry. This is especially true since trivalent chromium [Cr(III)] is necessary for proper nutrition, while hexavalent chromium [Cr(VI)] is extremely toxic, genotoxic, and carcinogenic. The main challenges associated with speciated analysis are related to reactive species that are continuously transformed or converted to other species during sample processing. Accurate determination of Cr(III) and Cr(VI) species require a method that is capable of monitoring and correcting for interconversion, bias, and instrumental error. Traditional quantitative methods, such …

Identification Of Degradation Products Formed From Glycerol And Terpenes In Aromatherapy Vaporizers, Alisha Ortiz

University Honors Theses

Degradation chemistry has been widely studied to assess the safety of aerosols in many fields. The study herein investigates the degradation products formed from MONQ personal aromatherapy devices- a new non-nicotine aromatherapy vape pen device on the market. These pens are marketed to alleviate symptoms of an unrecognized medical syndrome called “terpene deficiency”. These pens contain a glycerin (GL), or glycerol (VG), base and a blend of terpene-rich essential oils. Previous studies have investigated the degradation of both VG and terpenes and have shown that concerning compounds are released in the gas phase, including benzene, benzaldehyde, methacrolein and methyl vinyl …

Carbon Dots As Artificial Peroxidases For Analytical Applications, Shih-Chun Wei, Yang-Wei Lin, Huan-Tsung Chang

Journal of Food and Drug Analysis

Nanozymes have become attractive in analytical and biomedical fields, mainly because of their low cost, long shelf life, and less environmental sensitivity. Particularly, nanozymes formed from nanomaterials having high surface area and rich active sites are interesting since their activities can be tuned through carefully controlling their size, morphology, and surface properties. This review article focuses on preparation of carbon dots (C dots) possessing peroxidase-like activity and their analytical applications. We highlight the important roles of the oxidation states and surface residues of C dots and their nanocomposites with metal, metal oxides, or metal sulfides playing on determining their specificity …

Functionalized Gold Nanoparticles For Sensing Of Pesticides: A Review, Wei-Bin Tseng, Ming-Mu Hsieh, Che-Hsie Chen, Tai-Chia Chiu, Wei-Lung Tseng

Journal of Food and Drug Analysis

Pesticides are a family of non-biodegradable chemical compounds which widely used in agriculture to control pests and increase yield production. However, overuse or abuse of pesticides and their metabolites may cause potential toxicity for the environment as well as human health and all other living organisms, even at deficient concentrations. Consequently, the development of sensors for monitoring these compounds is significant. Recently, nanoparticles-based sensors have been extensively employed as a potential alternative or complementary analytical tool to conventional detection methods for pesticides. Among them, gold nanoparticles (AuNPs) owing to their unique optical properties have been developed as smart sensors with …

Observed Defects Of Swiss Cheese Based On The Microbiome Contribution To The Production Of Organic Acids, Vannessa D. Campfield

Boise State University Theses and Dissertations

The United States Department of Agriculture downgrades on the order of 17% of all Swiss cheese produced in the United States due to defects. Many of these defects are related to improper eye formation, number, distribution, or size; leading to an industry loss of over $69 million per annum. The microbiome in Swiss-type cheeses plays a significant role in eye development due to production of organic acids and gaseous emissions contingent on bacterial abundance and phenotype. The relationship between bacteria and the organic acids they produce leading to Swiss cheese defects can be correlated using Next-generation sequencing and high-performance liquid …

Design, Synthesis And Application Of Janus Gold Nanoprisms For Directed Self-Assembly., Md. Emtias Chowdhury

Electronic Theses and Dissertations

Colloidal Janus particles that possess more than one type of surface chemistry or functionalities have drawn significant interest due to their enormous potential in bottom-up synthetic strategies for complex superstructures. Moreover, the property of molecular recognition, tunability, and predictability of the DNA-mediated interactions enable a high degree of control over particle assembly to generate highly ordered nanostructures with emergent applications. In this dissertation, we present our works on the synthesis of Janus particles from anisotropic gold nanoprisms, and DNA- mediated assembly of nanoprisms and polymer beads in four major areas: 1) Facet selective asymmetric functionalization of gold nanoprisms for Janus …

The Application And Development Of Metabolomics Methodologies For The Profiling Of Food And Cellular Toxicity, Jade Woods

Department of Chemistry: Dissertations, Theses, and Student Research

Metabolomics is a rapidly growing field of study. Its growth reflects advancements in technology and an improved understanding of the impact of the environment on metabolism. As a result, metabolomics is now commonly employed to investigate and characterize human and plant metabolism. The first chapter of this thesis provides an introduction to metabolomics and an overview of the protocols for sample preparation, data collection and statistical analysis. The second thesis chapter describes in explicit detail the step-by-step process of extracting and analyzing metabolites collected from mammalian cells, specifically brain tissue with a focus on Parkinson’s disease. The chapter highlights important …

Fundamental Studies Of Nanomaterial-Mediated Photothermal Effects And Novel Applications In Visual Quantitative Disease Diagnoses, Wan Zhou

Open Access Theses & Dissertations

Infectious diseases and cancers frequently cause public health concerns and high burdens on health care globally. Early diagnosis of these diseases can provide an important guide on prevention, treatment, and prognosis in clinical practice. However, current laboratory diagnostic methods, such as nucleic acid- and protein-based detection methods, require sophisticated infrastructure, expensive and bulky instrumentation, well-trained personnel, and time-consuming processes, which significantly leads to high cost of detection assays and limit their wide accessibility, especially in low-resource settings. To address these issues, we have developed multiple simple, low-cost, and visual quantitative diagnostic methods based on nanomaterial-mediated photothermal effects for the detection …

Deep-Ultraviolet Laser Ablation For Biomolecular Analysis, Oluwaremilekun Omowunmi Lawal

LSU Doctoral Dissertations

New sampling and ionization techniques were developed using a deep-ultraviolet (DUV) laser at 193 nm wavelength for analysis of large biomolecules. A micrometer spatial resolution DUV laser ablation and capture system was constructed to sample tissue biomolecules. The spot size measurements of the focused beam showed that subcellular spots with ca. 2 μm diameter can be readily achieved with this wavelength. To demonstrate the extraction of tissue biomolecules with the DUV laser, regions of tissue sections were ablated and captured for offline proteomic and genomic analysis. The proteomic studies revealed that the tissue proteins were ejected without fragmentation and that …

Structure And Dynamics Of Phospholipid Vesicles And The Dependence On Nanoscale Interactions With Molecules Of Varying Complexity, Lakshapathy Widanelage Judith Upeka De Mel

LSU Doctoral Dissertations

In this dissertation, molecular interactions and changes imposed by nano-scale structures on phospholipid vesicles were investigated. 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) large unilamellar vesicles (LUVs) were used as the model system. Understanding changes of the bilayer structure, interfacial properties, lipid dynamics, and self-assembly, allows bridging relationships between biological cell membrane structure and dynamics to cellular functionalities. For example, membrane curvature changes are linked to membrane protein functions, although the exact mechanisms of control are not yet understood. Moreover, the knowledge gained from vesicle models allows exploring novel strategies for drug delivery applications. To achieve this, DOPC LUVs were synthesized and characterized by a …

A New Lc-Ms/Ms Technique For Separation Of Gangliosides Using A Phenyl-Hexyl Column: Systematic Separation According To Sialic Acid Class And Ceramide Subclass, Ashta Lakshmi Prasad Gobburi, Eric Wekesa Kipruto, Denise M. Inman, David J. Anderson

Chemistry Faculty Publications

A LC-MS/MS technique separated the bovine and mouse brain gangliosides monosialotetrahexosylgangliosides (GM1), disialotetrahexosylgangliosides (GD1a), trisialotetrahexosylgangliosides (GT1b) and tetrasialotetrahexosylgangliosides (GQ1b) using a phenyl-hexyl HPLC column and employing a linear methanol gradient in water, which is 0.028% in ammonium hydroxide. The gangliosides were separated according to sialic acid class, and within a particular class, gangliosides having different ceramide carbon chain lengths were also separated. All gangliosides of a particular sialic acid class eluted in characteristic retention time windows in the order of GQ1b, (earliest), GT1b, GD1a, and GM1 (latest). Within each specific retention time window for a particular ganglioside class, gangliosides were …

Fundamentals Of Distribution Of Relaxation Times For Electrochemical Impedance Spectroscopy, Jia Wang, Qiu-An Huang, Wei-Heng Li, Juan Wang, Quan-Chao Zhuang, Jiu-Jun Zhang

Journal of Electrochemistry

Electrochemical impedance spectroscopy (EIS) is a powerful electrochemical characterization technology, which has been widely used in the field of electrochemical energy, such as lithium-ion batteries, supercapacitors, fuel cells, etc. Distribution of relaxation time (DRT) is an EIS deconvolution technique which does not depend on the prior knowledge of the targeted research object. Furthermore, DRT can serve to separate and analyze physical and chemical processes which are highly overlapped in their EIS data. In order to encourage the application and popularization of DRT deconvolution technology, several core questions are addressed in this paper: (1) DRT deconvolution principle, implementation steps and important …

Graphene-Based Electrochemical Aptasensor For The Detection Of Salmonella Typhimurium, Shalini Muniandy

Student Works (2020-2029)

Recent foodborne outbreaks in multiple locations necessitate the continuous development of highly sensitive and specific biosensors that offer rapid and sensitive detection of foodborne pathogens. The emergence of electrochemical aptasensor which is a compact analytical device with a combination of an aptamer as the biorecognition element integrated on the transducer surface created a breakthrough in the detection of foodborne bacterial pathogens. Graphene has emerged as a promising nanomaterial for reliable detection of pathogenic bacteria due to its exceptional properties such as high electrical conductivity, large surface to volume ratio, high mechanical strength and its unique interactions with DNA bases of …

Developing Novel Tale-Based Rapid Detection Of Pathogenic Dna Utilizing 2d Graphene Oxide Nanosheets And Quantum Dots, Narayan Neupane

Masters Theses & Specialist Projects

A faster method of quantitative detection of specific dsDNA of pathogenic bacteria such as the Shiga toxin 2 gene (stx2) present in E. coli O157:H7 is of great importance. There is a need for a simple and facile method for sensitive detection of pathogenic gene which is crucial for the prevention and earlier treatment of any infectious diseases. A Transcriptional Activator-Like Effector (TALE) is a novel class of DNA-binding proteins with the unique modularity, flexibility and easy programmability compared to previously discovered DNA- binding proteins. TALEs can bind to any DNA sequences through its unique variable di- residues …

Hexacyanoferrate-Based Nanocomposites For The Electrochemical Sensing Of Hydrogen Peroxide And Nicotine, Lee Pui Kee

Student Works (2020-2029)

Metal hexacyanoferrate (MeHCF) is a unique material that not only acquired immense research interest in electrochemical sensing field but also possesses potential as energy storage material. As such, the present thesis sought to investigate the facile method to synthesis MeHCF-based nanocomposites and explore its possible applications. First, comparative research on the synthesis of Prussian blue-polypyrrole (PB-PPy) nanocomposite by novel self-assembly (SA) method and conventional electrodeposition technique was performed. PB-PPy nanocomposites were prepared by the novel self-assembly method and via the electrodeposition approach. The nanocomposites were compared in term of surface morphology and its electrochemical and electrocatalytic characteristics. The results indicated …

Development Of Ultrasonic-Based Ambient Desorption Ionization Mass Spectrometry, Linxia Song

USF Tampa Graduate Theses and Dissertations

Ambient desorption/ionization techniques (ADI) have drawn significant attention in mass spectrometric instrumentation development. The analyte classes that are successfully studied by any ADI mass spectrometry (MS) method strongly depends on how gas-phase ions are generated. Spray-based techniques may ionize molecules across a wide range of mass-to-charge ratios, but are commonly used for polar analyte, however, suffers from severe matrix effect. Contrastingly, methods employing electric (or laser) plasmas are capable of ionization of polar and nonpolar analytes suffering from less matrix effect, but primarily targeting those with low molecular masses. Thus far, developments of universal ionization methods, which do not depend …

Synthesis And Characterization Of Water-Soluble Polyaniline For Hydrazine Detection / Hazira Hussin, Hazira Hussin

Student Works (2020-2029)

In this study, polyaniline (PAni) was synthesized through the chemical oxidation method using aniline (Ani) as a monomer, hydrochloric acid (HCl) as a dopant, and ammonium persulphate (APS) as an initiator. PAni was rendered water soluble through treating with cellulose derivatives. Cellulose derivatives such as methylcellulose (MC), hydroxypropyl cellulose (HPC), and hydroxypropyl methylcellulose (HPMC) were used as a stabilizer to improve the solubility of PAni in an aqueous medium. The water-soluble PAni-cellulose derivative was applied as a chemical sensor for hydrazine detection. The chemical structures and electrical conducting behaviours of PAni-cellulose derivatives were investigated using Fourier transform infrared (FTIR) and …

Inversion Modeling Of Japonica Rice Canopy Chlorophyll Content With Uav Hyperspectral Remote Sensing, Yingli Cao, Kailun Jiang, Jingxian Wu, Fenghua Yu, Wen Du, Tongyu Xu

Electrical Engineering Faculty Publications and Presentations

Chlorophyll content is an important indicator of the growth status of japonica rice. The objective of this paper is to develop an inversion model that can predict japonica rice chlorophyll content by using hyperspectral image of rice canopy collected with unmanned aerial vehicle (UAV). UAV-based hyperspectral remote sensing can provide timely and cost-effective monitoring of chlorophyll content over a large region. The study was based on hyperspectral data collected at the Shenyang Agricultural College Academician Japonica Rice Experimental Base in 2018 and 2019. In order to extract the salient information embedded in the high-dimensional hyperspectral data, we first perform dimension …

Detection Of Melamine Based On The Suppressed Anodic Response Of Uric Acid By A Au-Ag Nanoparticles Modified Glassy Carbon Electrode, Yu-Hui Peng, Tsunghsueh Wu, Yang-Wei Lin

Journal of Food and Drug Analysis

We demonstrated a sensitive electrochemical method for the determination of non-electroactive melamine (Mel) using a modified glassy carbon electrode (GCE), with uric acid (UA) as the signal reporter. To increase the anodic response of UA, GCE was coated with Au–Ag nanoparticles and a Nafion thin film (Au–Ag/Nafion/GCE). The sensing mechanism was based on the competitive adsorption behavior of Mel on the Au–Ag/Nafion/GCE, which reduces the electroactive surface area of nanoparticles and thus hinders anodic response of UA. Under optimal conditions and the use of an analytical method of differential pulse voltammetry, this modified electrode detected Mel concentrations ranging from 2.5 …

Spatiotemporal Patterns Of Polychlorinated Dibenzo-P-Dioxins And Dibenzofurans And Dioxin-Like Polychlorinated Biphenyls In Foodstuffs In Air Quality Regions In Taiwan, Ching-Chang Lee, Wei-Hsiang Chang, Hsin-Tang Lin, Jung-Wei Chang

Journal of Food and Drug Analysis

High-fat food intake is the main source of dioxin-like compounds for humans, such as consumption of meat, dairy and eggs, and seafood products. Fruits, vegetables, and cereals have relatively low levels of dioxin-like compounds, but because of high consumption they also contribute to the food-borne intake. It is necessary to clarify dietary dioxin exposure affected by different food contamination levels and dietary habits among different geographic areas. We aimed to evaluate chronic dietary PCDD/Fs and DL-PCBs exposure in 725 individual foods in 14 categories in 6 Taiwan air quality regions (AQRs) and a total of 2,441 foods from 2004 and …

Isolation, Structure Elucidation, And Synthesis Of Natural Products From Marine Cyanobacteria, Keren Solomon

Electronic Theses and Dissertations

This thesis describes the isolation, structure elucidation, and synthesis of natural products from marine cyanobacteria. A crude extract from a cyanobacterium collected in Curacao showed selective affinity for the dopamine D₅ receptor in a screen against a panel of CNS receptors. Due to the high similarity of the D₅ and D₁ receptor, to date there are no known ligands that differentiate them. Attempts to purify the compound responsible for this affinity led to the isolation of the known compound caylobolide A. A second extract from a cyanobacterium collected in Panama underwent bioassay-guided fractionation and yielded the novel …

Electrostatic Denaturation Of Dna-Cisplatin Adducts, Eddie Madrigal

Master's Theses

In this thesis, electrochemical approaches are used to determine the properties of deoxyribonucleic acid (DNA) by electrostatic denaturation. The electrochemical routine involves an application of a destabilization potential, an equilibration potential, and a square wave voltammogram (SWV) to monitor the extent of melting. Our method uses a monolayer consisting of thiol modified DNA and mercaptohexanol on a gold electrode. These electrodes are then incubated in a complementary sequence tagged with methylene blue. By using our electrostatic denaturation technique, different parameters are explored, such as surface densities, surface coverages, and ionic strengths. As proof of concept, these techniques were applied toward …

Structural Characterization Of Organic Matter In Oil Shales Using Multiple Nuclear Magnetic Resonance Spectroscopic Techniques, Wenying Chu

Chemistry & Biochemistry Theses & Dissertations

Oil shale is a promising source of hydrocarbon fuel that is distributed throughout the world. The petroleum generating potential of oil shale is related to the molecular structure of the organic matter in source rock. The major fraction of organic matter of oil shale is termed kerogen, and due to its insolubility in organic solvents, ¹³C solid-state nuclear magnetic resonance (NMR) spectroscopy is one of the best ways to directly measure the insoluble organic matter without changing its chemical structures. This dissertation investigated oil shale samples using advanced solid-state ¹³C NMR spectroscopy techniques and high resolution magic angle …

Application Of Carbon Nanoparticles As Dna Detection Probe And Fluorescent Ink, Luckio Frank Owuocha

Graduate Theses/Dissertations

There is a significant interest in developing a sensitive, selective, efficient, and inexpensive method for rapid molecular diagnostic tests. This research aims to develop an inexpensive nucleic acid detection method by using DNA-conjugated carbon nanoparticles that exhibit fluorescence in the visible region. Carbon nanoparticles of this class can be detected without specialized equipment and have great promise toward the development of analytical methods that can be used in resource-limited environments with a lack of access to proper diagnostic and healthcare. We employed EDC-NHS (two-step) and EDC (one-step) coupling techniques to prepare DNA-conjugated carbon nanoparticles. The dot blotting method was adapted …

A Simple Predictive Model For Estimating Relative E-Cigarette Toxic Carbonyl Levels, Shawna Vreeke, Xijing Zhu, Robert Strongin

Chemistry Faculty Publications and Presentations

E-cigarette devices are wide ranging, leading to significant differences in levels of toxic carbonyls in their respective aerosols. Power can be a useful method in predicting relative toxin concentrations within the same device, but does not correlate well to inter-device levels. Herein, we have developed a simple mathematical model utilizing parameters of an e-cigarette’s coil and wick in order to predict relative levels of e-liquid solvent degradation. Model 1, which is coil length/(wick surface area*wraps), performed in the moderate-to-substantial range as a predictive tool (R² = 0.69). Twelve devices, spanning a range of coil and wick styles, were analyzed. …

Toward Development Of A Paper-Based Microanalytical Device For Heavy Metal Ion Detection By Enzyme Inhibition, Adjoa Otubea Adams

Graduate Theses/Dissertations

In recent years, paper-based microanalytical devices have attracted great attention in broad application areas including the colorimetric detection of heavy metal ions. The simplicity, portability, and low cost of the devices offer unique advantages over conventional instrumental analysis. This project utilizes the inhibition of an enzyme-catalyzed reaction by metal ions to develop a paper-based analytical device for the detection of heavy metal contaminants such as mercury. I selected alkaline phosphatase for this study. This enzyme possesses Mg and Zn ions in its active site. Therefore, the competitive displacement of these metal ions and/or denaturation of the enzyme by heavy metal …

Visualization Without Vision – How Blind And Visually Impaired Students And Researchers Engage With Molecular Structures, Croix J. Laconsay, Henry B. Wedler, Dean J. Tantillo

Journal of Science Education for Students with Disabilities

This article examines the tools and techniques currently available that enable blind and visually impaired (BVI) individuals to visualize three-dimensional objects used in learning chemistry concepts. How BVI individuals engage with and visualize molecular structure is discussed and recent tactile (or haptic) and auditory methods for visualization of various chemistry concepts are summarized. Remaining challenges for chemistry education researchers are described with the aim of highlighting the potential value of educational research in further enabling BVI students to pursue careers in science, technology, engineering, and mathematics (STEM) fields.