Analytical Chemistry Commons^™

Statistical Comparison Of Results Of Redox Titrations Using K-2 Cr-2o-7 And Kio-3 In The Undergraduate Analytical Chemistry Lab, David W. Randall, Luis K. Garibay

Faculty Publications

Reducing the quantity of hazardous substances used and hazardous waste generated by under- graduate laboratory experiments is important. However, simply replacing hazardous compounds with less hazardous reagents may not retain the pedagogical (or analytical) goal of the experiment if the chemistry does not fundamentally work. We evaluated several literature-based replacement oxidants for K2Cr2O7 (potassium dichromate) and identified KIO3 (potassium iodate) as the only che- mically viable alternative for thiosulfate standardizations, consistent with use of iodate by others. Using ANOVA analysis, two years of student results where K2Cr2O7 was used as the oxidant were compared with two years of student results …

Physical And Chemical Attributes Of A Genetically Modified Fruit Pectin, Carl Patrick Littrell

Open Access Theses

Pectin is an important polymer used in the food industry as a thickening and gelling agent. Though pectin is ubiquitous in plants, chemical and structural differences among pectin molecules prevent most from being viable for industrial use. Enzymes found naturally in fruit cell walls during the ripening process impair many desirable attributes of fruit pectins, rendering them unsuitable for industrial applications. Pectin methylesterase (PME) is one such enzyme whose expression can be altered during ripening through the use of recombinant genetic engineering. Reduction in levels of PME results in increased degree of methylation and molecular size of pectin, greatly increasing …

Investigation Into The Control Of Melittin Secondary Structure And Antimicrobial Activity, Zachary B. Molinets

Open Access Theses

Antimicrobial resistance has been an exponentially growing problem since the discovery of antibiotics. Antibiotics have been misused for many years and this misuse has grown into a real problem for the medical community. While there are countless safeguards to prevent infection by a resistant strain of bacteria, there are still many plagued by it and must be treated with sometimes dangerous antibiotics. Melittin, along with many other peptides, contain potent antimicrobial properties, but are also toxic toward enthrocytes. The control of the secondary structure of peptides provides the key to adjusting their activity.

Synthesis And Characterization Of Crystalline Iron Nanoparticles From Zerovalent Iron Sandwich Complexes, Anh Tue Nguyen

Open Access Theses

In this project we present a systematic study on the synthesis of crystalline iron nanocubes by thermal decomposition of an iron sandwich complex, ( π-C₅H₅)Fe⁰(π-C ₆H₇), in the presence of oleylamine and oleylamine.HCl as surfactants and n-decane as a solvent. The presence of oleylamine.HCl is essential for the reproducible formation of crystalline iron cores.^ Reaction parameters such as temperature, surfactant concentration, effect of counterion, and organoiron reagent structure were investigated in order to obtain iron nanoparticles with uniform size and shape. The nanoparticles, which were characterized by …

Separation Of On-Column Labeled Model Proteins With Packed Capillary Electrophoresis, Yingxu Hao

Open Access Theses

Protein drugs are increasingly developed in the pharmaceutical company. Under the regulation of FDA, high purity of therapeutic proteins needs to be maintained. Before putting those drugs in the market, fast and efficient method is in need to achieve homogeneity. Traditionally, polyacrylamide gel electrophoresis (PAGE), capillary electrophoresis (CE), and size-exclusion chromatography (SEC) are used for the purification process. These methods have the disadvantages of low time and cost efficiency, and this quality assurance process has become the bottleneck of production. In our group, sub-micron silica colloidal particles with polyacrylamide layer on the surface are packed inside capillaries to increase the …

Metal-Protein Interactions For Proteomics Applications, Keerthi B Jayasundera

Open Access Dissertations

In the quest of deciphering biological mechanisms, the understanding of proteins and their functions is a vital component. However the complexity of the proteome poses an immense challenge for analytical chemists to explore it comprehensively. Currently mass spectrometry is at the forefront of proteome analysis, providing great capabilities to couple with modern separation techniques for wide applications. One major objective of current proteomic technologies is to identify proteins of interest among high background, in particular from complex biological samples. A variety of techniques have been developed over the years to simplify protein samples, which are broadly classified as enrichment, high …

Determination Of Corrosion Inhibitor Lubricity Improver In Jet Fuel By Liquid Chromatography-Electrospray Ionization Mass Spectrometry, David W. Johnson, Milissa Flake, Ryan Adams

Chemistry Faculty Publications

Military jet fuel (JP-8) is very similar to commercial jet fuel (Jet A) except for the presence of three additives, fuel system icing inhibitor, corrosion inhibitor–lubricity improver (CI-LI), and antistatic additive, which are added to improve characteristics of JP-8. Of particular interest is the CI-LI additive; the most common active ingredient is a dimer of linoleic acid. This article focuses on quantification of the active ingredient in the CI-LI additive by liquid chromatography–mass spectrometry (LC–MS). This method will allow the determination of CI-LI content in military jet fuel samples.

Gas-Phase Ion/Ion Reactions Of Biomolecules: An Examination Of Carboxylate Reactivity And Arginine Based Non-Covalent Complexes, Nathan Zachary Barefoot

Open Access Theses

The advent of Electrospray Ionization with the ability to generate multiply charges ions has contributed significantly to the study of gas-phase ion/ion reactions. With the tools available in mass spectrometry it has been shown that these reactions are effective at transforming one type of gaseous ion into another through a series of reactions. This work examines some of these reactions and their application to field of proteomics specifically focusing on the amino acids of arginine and lysine. NHS reagents have been shown to react to both of these molecules with in the gas-phase under different conditions but have relies on …

Surface Enhanced Raman Spectroscopic Studies Of Pyridine Adsorbed On Ti/Au@Sio2 Film Electrode, Min-Min Xu, Ke Liu, Qing-Hua Guo, Jian-Lin Yao

Journal of Electrochemistry

This study was performed based on shell-isolated nanoparticles-enhanced Raman spectroscopy (SHINERS) technology. The Au@SiO₂ nanoparticles were prepared and characterized by TEM and cyclic voltammetry. It was shown that the shell of SiO₂ was compact. The high quality signal measured by surface enhanced Raman spectroscopy (SERS) was obtained from the adsorbed pyridine on Ti/Au@SiO₂ electrode. The origin of the SERS signals was further confirmed by testing Pt and Ni electrodes. In addition, potential dependent adsorption behavior was investigated. It was found that pyridine was adsorbed parallel on the surface from -0.1 V to -0.6 V, and converted to …

Horseradish Peroxidase-Attapulgite Clay Nanocomposites: Fabrication And Application To Sensing The Extracellular H2O2 Released From Cells, Ping Wu, Chen-Xin Cai

Journal of Electrochemistry

The nanostructured attapulgite clay was employed as a support matrix for immobilizing horseradish peroxidase (HRP). FTIR and electrochemical methods demonstrated that HRP had been effectively assembled on attapulgite surface with the formation of HRP-attapulgite nanocomposites. The HRP-attapulgite hybrid was deposited on the glassy carbon (GC) electrode forming the HRP-attapulgite/GC electrode. Cyclic voltammetric results showed a pair of well-defined redox peaks, which were ascribed to direct electron transfer (DET) of HRP, with the formal potential E₀′ = -335 mV (vs. SCE) in the phosphate buffer solution (PBS, pH 7.0). The dependence of E₀′ on solution pH indicated …

23Na Mas Nmr Spectroscopic Study Of Na2Mnpo4F As Cathode Material For Sodium-Ion Battery, Xu Hou, Gui-Ming Zhong, Xiao-Chen Lin, Zi-Geng Liu, Xiao-Biao Wu, Yong Yang

Journal of Electrochemistry

The Na₂MnPO₄F is one of the promising cathode materials for the sodium ion batteries. In the paper, we employed the ex situ X-ray diffraction and solid state NMR techniques to study the charge and discharge processes of this material, including the crystal structure and sodium sites changes. The ex situ x-ray diffraction patterns showed that two new diffraction peaks could be observed at 31^o and 36^o indicating an intermediate phase formed with the extraction of Na⁺. From the ²³Na MAS NMR spectrum of the material, three peaks were seen at -209 …

Nitroxide Radicals For Low Frequency Electron Paramagnetic Resonance Imaging (Epri), Joshua R. Biller

Electronic Theses and Dissertations

Optimization of nitroxides as probes for EPR imaging requires detailed understanding of spectral properties such as spin lattice relaxation times, spin packet linewidths, and nuclear hyperfine splitting. Initial measurements of relaxation times for six low molecular weight nitroxides at X-band stimulated further measurement at frequencies between 250 MHz and 34 GHz. The impact of tumbling was studied with perdeuterated 2,2,6,6-tetramethyl-4-piperidinyl-1-oxyl (PDT) in five solvents with viscosities resulting in tumbling correlation times, τ_R, between 4 and 50 ps. A set of three ¹⁴N/¹⁵N pairs of nitroxides in water was selected such that τ_R varied between …

An Investigation Of Poly(N-Isopropylacrylamide) For Applications With Microfluidic Paper-Based Analytical Devices, Haydn Thomas Mitchell

Master's Theses

N,N′-methylenebisacrylamide-crosslinked poly(N-isopropylacrylamide), also known as P(NIPAM), was developed as a fluid delivery system for use with microfluidic paper-based analytical devices (microPADs). MicroPADs are postage-stamp-sized devices made out of paper that can be used as platforms for low-cost, simple-to-use point-of-care diagnostic assays. P(NIPAM) is a thermally responsive polymer that absorbs aqueous solutions at room temperature and will expel the solutions to microPADs when heated. The fluid delivery characteristics of P(NIPAM) were assessed, and P(NIPAM) was able to deliver multiple solutions to microPADs in specific sequences or simultaneously in a laminar-flow configuration. P(NIPAM) was then shown to be suitable …

Development And Validation Of Lc–Ms/Ms Method For Quantitative Determination Of (−)-Securinine In Mouse Plasma, Simuli L. Wabuyele, David Wald, Yan Xu

Chemistry Faculty Publications

(−)-Securinine (SE) is a major alkaloid found in plant Securinega suffruticosa, which has a wide range of pharmacological activities including anticancer, anti-parasitic and central nervous system stimulating effects, etc. To aid the pharmacological study of SE, we developed an LC–MS/MS method for quantitative determination of SE in mouse plasma. In this method, plasma samples were first prepared with salting-out assisted liquid–liquid extraction using cold acetonitrile (−20 °C) and 2.00 M ammonium acetate. Separation of SE and the internal standard (IS) from sample matrix was achieved on a Gemini Nx C18 column using 40% acetonitrile and 60% 10.0 mM ammonium acetate …

Ionic Liquids In Micro Extractions And Gas Chromatographic Stationary Phases, Ramkumar Dhandapani

Seton Hall University Dissertations and Theses (ETDs)

Ionic liquids are salts that exist entirely as ionic species. They are composed of cation, anion and side chain or linkage group. Due to the different combination of the these groups, the ionic liquid exhibits unique selectivity. Their applications are enormous in the field of analytical chemistry.

The interest of using ionic liquids as gas chromatographic stationary phase has increased in recent years. The low volatility, tailorable physico-chemical property and high thermal stability of ionic liquids make them an ideal choice for gas chromatographic stationary phase. For the present research, commercially available ionic liquid capillary columns were investigate for thermodynamics …

Glass Foundation Chemosensor Synthesis And Functionality Analysis, Justin D. Dancer

Master's Theses

Chemosensors are created through a series of reaction steps on controlled pore class (CPG) and terminate with a Cu²⁺ metal binding site. Each monolayer of reactant insures that the metal binding site exposed to solution would serve as an indicator displacement assay (IDA) sensor. The purpose of this research is to create a molecular sensor with a high density of terminal metal sites to quantify bidentate substrates. To accomplish this, each synthetic step of the sensor is examined in order to test the effects of new linkers, ligands, and variously sized dendrimers to see if small structural changes could …

Cyanide Toxicokinetics: The Behavior Of Cyanide, Thiocyanate And 2-Amino-2-Thiazoline-4-Carboxylic Acid In Multiple Animal Models, Raj K. Bhandari, Robert P. Oda, Ilona Petrikovics, David E. Thompson, Matthew Brenner, Sari B. Mahon, Vikhyat S. Bebarta, Gary A. Rockwood, Brian A. Logue

Chemistry and Biochemistry Faculty Publications

Cyanide causes toxic effects by inhibiting cytochrome c oxidase, resulting in cellular hypoxia and cytotoxic anoxia, and can eventually lead to death. Cyanide exposure can be verified by direct analysis of cyanide concentrations or analyzing its metabolites, including thiocyanate (SCN⁻) and 2-amino-2-thiazoline-4-carboxylic acid (ATCA) in blood. To determine the behavior of these markers following cyanide exposure, a toxicokinetics study was performed in three animal models: (i) rats (250–300 g), (ii) rabbits (3.5–4.2 kg) and (iii) swine (47–54 kg). Cyanide reached a maximum in blood and declined rapidly in each animal model as it was absorbed, distributed, metabolized and …

Tetracyclines In Swine Waste, Natalie Kaye Jones

Masters Theses & Specialist Projects

Antibiotics are added to animal feeds as prophylactic agents and to encourage weight gain in livestock. However, there is concern that the widespread use of antibiotics in animal agriculture encourages for the selection of resistance genes and has contributed to the rise of multiply antibiotic resistant strains of pathogenic bacteria. For this reason, there is interest in quantifying antibiotics in environmental samples. The determination of three antibiotics in swine waste, namely chlortetracycline, tetracycline and oxytetracycline, using LC-MS with electrospray ionization is presented here in. Antibiotics from swine waste were quantified across the lifespan of the swine. Trends were present in …

Comparative Studies On Standard And Fire-Rated Gypsum Wallboards., Harika Javangula

Masters Theses & Specialist Projects

The long term goal of this research is to improve the fire resistance of gypsum wallboard (GWB). Gypsum wallboard consists mainly of gypsum, i.e. calcium sulfate dihydrate, CaSO₄•2H₂O. In buildings, the chemical, mechanical and thermal properties of gypsum wallboard play an important role in delaying the spread of fire. To build a fire resistant GWB, it is very important to study the thermal, mechanical, physical and chemical properties of regular GWB and various types of fire-resistant wallboards available commercially in the market. Various fire-resistant GWBs have been compared and contrasted with reference to a standard wallboard …

Electrically Controlled Formation And Release Of Admicelles For Solid Phase Extraction, Sukyeon Lee

Masters Theses & Specialist Projects

Solid phase extraction is one of the most widely used methods to concentrate diluted compounds in a solution. Substances can be extracted into admicelles and hemimicelles, which are surface adsorbed micelles and surfactant monolayers, respectively. Investigations of the electrical control of surfactants on surfaces for the purpose of analyte preconcentration prior to chromatographic analysis are presented. The surfactant layer serves as the “stationary phase” in a solid phase extraction sorbent scenario. Analytes are adsorbed on this layer, and then released from the solid phase via surfactant removal. The attachment and removal of the surfactant are controlled by means of an …