Analytical Chemistry Commons^™

Fundamentals Of Electrochemical Impedance Spectroscopy For Macrohomogeneous Porous Electrodes, Xiang Li, Qiu-An Huang, Wei-Heng Li, Yu-Xuan Bai, Jia Wang, Yang Liu, Yu-Feng Zhao, Juan Wang, Jiu-Jun Zhang

Journal of Electrochemistry

Electrochemical impedance spectroscopy (EIS) can be used to diagnose charge transfer reactions and mass transport in porous electrodes. The charge transfer reactions include interfacial charge accumulation and charge conduction as well as electrochemical reaction. In this paper, the complex phasor method is developed under the macrohomogeneous assumption to build an impedance model of porous electrodes for clarifying several vague expressions in the traditional approaches. The following researches are carried out: (1) Identifying characteristic parameters for the porous electrodes, including electrode electronic conductivity σ₁, electrolyte ionic conductivity σ₂, interface charge transfer conductivity g_ct, unit area …

Bioadhesives, Mark Alan Helle, Chin Li Cheung

Department of Chemistry: Faculty Publications

Materials and methods for preparing reactive lignin and for preparing a bio - based adhesive are described herein.

Lateral Growth Of Xenon Hydrate Films On Mica, Avinash Kumar Both, Chin Li Cheung

Department of Chemistry: Faculty Publications

In this paper, we report an in situ optical microscopy study of lateral growth of xenon (Xe) hydrate thin films on mica at sub-zero temperatures. The interactions between a solid surface and water molecules can strongly affect the alignment of water molecules and induce ice-like ordered structures within the water layer at the water-surface interface. Mica was chosen as a model surface to study the surface effect of hydrophilic sheet silicates on the lateral growth of Xe hydrate films. Under the experimental conditions, the lateral growth of Xe hydrate films was measured to be at an average rapid rate of …

Comparison Of Design Approaches For Low-Cost Sampling Mechanisms In Open-Source Chemical Instrumentation, Greggory Murray, Samuel Bednarski, Michael Hall, Samuel W. Foster, Sijun Jin, Joshua J. Davis, Wei Xue, Eric Constans, James P. Grinias

College of Science & Mathematics Departmental Research

Robotic positioning systems are used in a variety of chemical instruments, primarily for liquid handling purposes, such as autosamplers from vials or well plates. Here, two approaches to the design of open-source autosampler positioning systems for use with 96-well plates are described and compared. The first system, a 3-axis design similar to many low-cost 3D printers that are available on the market, is constructed using an aluminum frame and stepper motors. The other system relies upon a series of 3D printed parts to achieve movement with a series of linker arms based on Selective Compliance Assembly Robot Arm (SCARA) design …

Inductively Coupled Plasma Optical Emission Spectroscopy (Icp-Oes) Analysis Of Trace Metals In Cigarette Litter Collected At Mcneese State University In Lake Charles, La, United States, Liliya Snaychuk, Trey Vaughan, Zachary Ullery, Chris Douvris, Derek Bussan

EKU Faculty and Staff Scholarship

Cigarette smoking is the most commonly used form of tobacco in the world. It is practiced by a large portion of the population, especially young people. These people often ignore or disregard the harmful toxic impacts that cigarettes have on both themselves and the environment. The United States Center for Disease Control estimates that nearly 40 million U.S. adults still smoke cigarettes, with nearly 1600 U.S. youth starting cigarette smoking every day. Although it is well-known that smoking cigarettes is addictive and leads to a numerous health conditions including cancer, chronic pulmonary and heart disease, the effect of disposing the …

Hemoglobin-Modified Core–Shell Fe3o4@Au Nanostructures For The Electrochemical Detection Of Acrylamide, Endang Saepudin, Tri Yuliani, Mochammad Arfin Fardiansyah Nasution, Munawar Khalil, Jong Wook Hong, Tribidasari Anggraningrum Ivandini

Makara Journal of Science

In this study, electrochemical detection of acrylamide using hemoglobin (Hb)-modified core–shell Fe₃O₄@Au nanostructures was conducted. Fe₃O₄ nanoparticles (~4.9 nm) and core–shell Fe₃O₄@Au (5.0–6.4 nm) nanostructures were successfully synthesized by the thermal decomposition method. Electrochemical investigation revealed that the optimum amount of Hb of 2 mg/mL could be immobilized in 0.1 M acetate buffer solution (pH = 6). Moreover, the detection of acrylamide using Fe₃O₄@Au/Hb was evaluated by the cyclic voltammetry technique. A linear calibration curve (R² = 0.98) in the concentration range of …

Rapid Quantitative Analysis Of Toxic Norditerpenoid Alkaloids In Larkspur (Delphinium Spp.) By Flow Injection - Electrospray Ionization – Mass Spectrometry, Dale R. Gardner, Stephen T. Lee, Daniel Cook

Poisonous Plant Research (PPR)

A rapid flow injection - electrospray ionization – mass spectrometry (FI-ESI-MS) method for the quantitative and qualitative analysis of norditerpenoid alkaloids in larkspur plants was developed. The FI-ESI-MS method was calibrated for alkaloid concentrations with larkspur plant samples against an existing Fourier transform infrared spectroscopy FTIR method. There was a strong correlation (r = 0.9926, r = 0.9891) between the FTIR and FI-ESI-MS methods. The relative standard deviation (RSD) for all measurements were ≤ 6.2 % except for the sample with the lowest concentration which was 19%. The sample throughput of the FI-ESI-MS method is much higher than the FTIR …

Effects Of Fluoride On Submandibular Glands Of Mice: Changes In Oxidative Biochemistry, Proteomic Profile, And Genotoxicity, Leidiane Alencar De Oliveira Lima, Giza Hellen Nonato Miranda, Walessa Alana Bragança Aragão, Leonardo Oliveira Bittencourt, Sávio Monteiro Dos Santos, Michel Platini Caldas De Souza, Lygia S. Nogueira, Edivaldo Herculano Corrêa De Oliveira, Marta Chagas Monteiro, Aline Dionizio, Aline Lima Leite, Juliano Pelim Pessan, Marília Afonso Rabelo Buzalaf, Rafael Rodrigues Lima

Department of Chemistry: Faculty Publications

Although fluoride (F) is well-known to prevent dental caries, changes in cell processes in different tissues have been associated with its excessive exposure. Thus, this study aimed to evaluate the effects of F exposure on biochemical, proteomic, and genotoxic parameters of submandibular glands. Twenty one old rats (n = 30) were allocated into three groups: 60 days administration of drinking water containing 10 mgF/L, 50 mgF/L, or only deionized water (control). The submandibular glands were collected for oxidative biochemistry, protein expression profile, and genotoxic potential analyses. The results showed that both F concentrations increased the levels of thiobarbituric acid–reactive …

Two-Dimensional Monolayer Salt Nanostructures Can Spontaneously Aggregate Rather Than Dissolve In Dilute Aqueous Solutions, Wenhui Zhao, Yunxiang Sun, Weiduo Zhu, Jian Jiang, Xiaorong Zhao, Dongdong Lin, Wenwu Xu, Xiangmei Duan, Joseph S. Francisco, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

It is well known that NaCl salt crystals can easily dissolve in dilute aqueous solutions at room temperature. Herein, we reported the first computational evidence of a novel salt nucleation behavior at room temperature, i.e., the spontaneous formation of two-dimensional (2D) alkali chloride crystalline/non-crystalline nanostructures in dilute aqueous solution under nanoscale confinement. Microsecond-scale classical molecular dynamics (MD) simulations showed that NaCl or LiCl, initially fully dissolved in confined water, can spontaneously nucleate into 2D monolayer nanostructures with either ordered or disordered morphologies. Notably, the NaCl nanostructures exhibited a 2D crystalline square-unit pattern, whereas the LiCl nanostructures adopted non-crystalline 2D hexagonal …

Spectral Analysis Of A New Electronic Transition Of Platinum Fluoride, Ptf, Carol Welch

Undergraduate Research Symposium

The electronic landscape of platinum containing molecules has been the focus of numerous spectroscopic studies in recent years, because of the difficulty in describing electronic structure theoretically due to electronic correlations and relativistic effects. A collective effort by spectroscopitsts and theoreticians to investigate the diatomic molecule platinum fluoride, PtF, has included research such as developing potential energy diagrams and performing analyses on rotational transitions with microwave spectroscopy. One group observed electronic transitions of PtF using laser vaporization/reaction with jet free expansion and laser induced spectroscopy. A highly effective method for observing and analyzing electronic transitions of small, metal-containing molecules like …

Evaluation Of The Potential Of Automated Sem-Eds Analysis For The Discrimination Of Inorganic Soil Particles, Anna S. Duggar

Dissertations, Theses, and Capstone Projects

Soil, that complex mixture of minerals, organic particles, chemicals, and anthropogenic materials, is ubiquitous and easily transferred, which gives it forensic relevance. Forensic soil analysis has traditionally included the identification and comparison of both organic and inorganic components, the inorganic portion being most commonly examined by light microscopy and other instrumental techniques. Predominantly, the inorganic materials in soil are naturally-occurring minerals, contributed as grains from the surrounding bedrock, which gives a soil its regional character. That parent material then undergoes physical, chemical, and anthropogenic changes producing wide geographic variation within a single region. This variation forms the basis for potential …

Don't Sell Them Short, There's More To Bacterial Natural Products Than Antibiotics, Alison Clare Domzalski

Dissertations, Theses, and Capstone Projects

Recent genomic studies of microbiomes have revealed an overwhelming number of biosynthetic genes of unknown function. Most of these “cryptic” biosynthetic genes are not expressed in laboratory monocultures of individual microbes. Thus, there remains tremendous untapped potential for natural products discovery. Here we employ mixed microbial culture (MMC) as a simple yet powerful approach to awaken cryptic biosynthetic gene clusters. Our preliminary studies demonstrated that arrays of metabolites could be induced in MMCs upon environmental cues, such as surface adhesion. Using this system, we have screened, identified, and isolated bioactive bacterial metabolites, which were characterized structurally and biologically. Of the …

Immobilized-Enzyme Reactors Integrated Into Analytical Platforms: Recent Advances And Challenges, Bert Wouters Dr, Sinead Currivan, Noor Abdulhussain, T. Hankemeier, Peter J. Schoenmakers

Articles

Immobilized-enzyme reactors (IMERs) are flow-through devices containing enzymes that are physically confined or localized with retention of their catalytic activities. IMERs can be used repeatedly and continuously and have been applied for (bio)polymer degradation, proteomics, biomarker discovery, inhibitor screening, and detection. Online integration of IMERs with analytical instrumentation, such as high-performance liquid chromatography (HPLC) systems, reduces the time needed for multi-step workflows, reduces the need for sample handling, and enables automation. However, online integration can also be challenging, as reaching its full potential requires complex instrumental setups and experienced users. This review aims to provide an assessment of recent advances …

Indicators Of Senescence And Their Relationship With The Antioxidant Response Element In Ovarian Cancer Cells—Toward A More Encompassing View Of Enzyme Activity Levels In Cells, Shaniqua Analycia Hayes

LSU Doctoral Dissertations

Enzymes and other related proteins are promising targets as biomarkers for cancer diagnostics, and it is therefore important to be able to quantify intracellular enzyme activity levels, not just presence of enzyme. Thus, there is a great need for the development of methods that offer spatiotemporal quantification of intracellular enzyme activity levels in respiring 2- and 3-dimensional cultures or their sample-processed variants. Previous studies have demonstrated that ß-gal is upregulated in senescence and in select ovarian cancers, and its expression/activity is upregulated when cells are under oxidative stress conditions. To that end, the primary goal of this work was to …

Quantifying Phosphatidylethanol From Blood Samples, James V. Defrancesco, Majid Afshar

Chemistry: Faculty Publications and Other Works

Disclosed herein is a method for quantifying phosphatidylethanol (“ PEth ”), direct ethanol biomarker, from a blood sample using gas chromatography mass spectrometry. The method disclosed herein is useful for diagnosing acute and chronic alcohol abuse.

The Development And Optimization Of A Two-Dimensional Lc-Qqq-Ms-Method For The Combined Analysis Of Synthetic Cannabinoids And Designer Cathinones In Urine, Holly Penefsky

Electronic Theses and Dissertations

The compounds and chemical compositions of synthetic cannabinoids and designer cathinones are designed to mimic the intoxicating effects of D⁹-tetrahydrocannabinol and amphetamines, respectively. In order to skirt existing drug laws, non-controlled ingredients are used, and the original chemical structures of current drugs are being modified using analogs or derivatives. These continually changing chemical compositions pose a problem for policymakers, and forensic and analytical scientists, as users are able to attain a “legal high” and avoid detection in standard drug screens. Commonly, toxicology laboratories utilize a screening method, such as immunoassay, for the presumptive identification of designer drugs. When …

Doping Of Conjugated Polymers: Preparation, Characterization And Device Fabrication, Kan Tang

Dissertations

Semiconducting conjugated polymers (CPs) as emerging materials for advanced electronic applications such as sensors, OPVs, and OEFTs has become an intriguing research topic in the past decades. It opens a new avenue of “flexible” electronics, which has shown great potential in next-generation electronic devices.

However, due to the nature of CP materials and related solution processing techniques, unlike almost perfectly crystalline silicon materials, CPs in the solid-state often exhibit much lower crystallinity if it is not complete amorphous, which severely hinder the electronic property and optical property of the materials. The crystallinity of CPs in a film is often uniquely …

Comparison Of Supported Liquid Extraction And Solid Phase Extraction Of Methamphetamine From Urine And Method Validation By Gas Chromatography-Mass Spectrometry, Taylor Hood

Master's Theses

Applications of SLE (supported liquid extraction) is a relatively new extraction technique that is not widely used in forensic toxicology. SLE is also easier and less time consuming than traditional LLE (liquid-liquid extraction) and SPE (Solid phase extraction). This work will compare the extraction efficiencies between SLE and SPE for methamphetamine from urine with detection and quantitation using GC-MS (gas chromatography- mass spectrometry). The SLE cartridges provide better analyte recoveries, eliminate emulsion formation, and allow for shorter processing time than other extraction techniques. The SPE cartridges used have a mixed-mode non-polar/strong cation exchange retention mechanism to extract basic analytes like …

Mass Spectrometry Based Metabolomics And Lipidomics., Fang Yuan

Electronic Theses and Dissertations

Metabolomics and lipidomics studies are important to understand living organisms at the molecular level. In this dissertation, I conducted various untargeted and targeted metabolomics and lipidomics studies using mass spectrometry based analytical platforms. Firstly, I investigated the androgen depletion effects on fecal metabolites in a mouse model of systemic lupus erythematosus and metabolite biomarkers for colorectal cancer using two-dimensional gas and liquid chromatography-mass spectrometry. Secondly, I investigated the relationship between gut microbiota-mediated resistance and susceptibility to malaria and the production of short-chain fatty acids using gas chromatography-mass spectrometry. Thirdly, I developed a high-throughput liquid chromatography-mass spectrometry method to profile long-chain …

Nitrogen-Doped Carbon Fiber Ultramicroelectrodes As Electrochemical Sensors For Detection Of Hydrogen Peroxide, Eric Wornyo

Electronic Theses and Dissertations

Carbon fiber ultramicroelectrodes (CF-UMEs) are commonly used as electrochemical probes and sensors due to their small size, fast response, and high signal-to-noise ratio. Surface modification strategies are often employed on CF-UMEs to improve their selectivity and sensitivity for desired applications. However, many modification methods are cumbersome and require expensive equipment. In this study, a simple approach known as soft nitriding is used to prepare nitrogen-doped CF-UMEs (N-CF-UMEs). Nitrogen groups introduced via soft nitriding act as electrocatalytic sites for the breakage of O-O bonds during the reduction of peroxides like H₂O₂, a common target of biosensing strategies. …