Analytical Chemistry Commons^™

Uhplc In The Analysis Of Drug Components, Rana Chandra Sekhar Reddy Pulagam

All Capstone Projects

The main objective of this article is to highlight the new trends that have emerged in the enhancement of the HPLC which have given rise to the use of UHPLC. This innovative tool is much more reliable and effective as compared to HPLC, in the investigation of many chemical compounds. In this article, special insight is given on the changes that have been made with regards to both instruments. In this article focus is also placed on the implementation of UPLC in various fields of interest, in order to enhance the processes for which it is utilized. The pros and …

Mass Spectral Imaging For Analysis Of Pharmaceutical Ingredients, Abdul Majid Mohammed

All Student Theses and Dissertations

Mass spectral imaging (MS-imaging) is a modern technique used for the analysis and characterization and distribution of pharmaceutical ingredients , drugs, peptidies, lipids, and other bioactive species in tissue section/ Tissue prints. Although now widely accepted, there remains a host of competing and complementary techniques including DESI, MALDI, SIMS, and DART ionization techniques that allow the researchers to obtain appreciable ion intensities for mapping purposes. Instrumentation further is, rapidly advancing with significant progress in TOF, ion trap, and quadrupole instrumentation for mapping. In this review, I will examine the current status and role of MS-imaging with emphasis on analysis of …

Development Of Method For Detection Of Lead In Samples Collected From Keweenaw Peninsula Mines, Michigan In Collaboration With Environmental Biology Research Students, Sindhu Reddy Aaireddy

All Capstone Projects

Mining is one of the most important industries and a main cause of global pollution due to release of heavy metals into air, water, and soil. Some of these elements are persistent in the environment for years and bioaccumulation in living organisms causing toxic effects. Such elements are known as PBTs (persistent, bioaccumulate and toxic). The nature of toxicity depends on the properties, size of population exposed to it and period of exposure. For this reason, we are interested in developing a method to detect heavy metals in soil samples, mine tailings, plant and animal samples collected from surroundings of …

Metal-Organic And Supramolecular Architectures Based On Mechanically Interlocked Molecules, Isurika Rosini Fernando

Dissertations

The focus of this work is on mechanically interlocked molecules (MIMs), which have unusual physicochemical and mechanical properties with potential applications in nano-scale/molecular devices and high strength materials.

Rotaxanes, for example, consist of an axle-like molecule threaded through a wheel-like molecule, with bulky groups at the two ends of the axle preventing the wheel from dissociating. The position of the wheel along the axle can be switched in a controllable and reversible manner by applying external stimuli, a feature that might lead to the next generation of computers. Molecularly woven materials (MWMs), another example of molecules with mechanically interlocked features, …

Monolayer-Protected Nanoparticle Doped Xerogels As Functional Components Of Amperometric Glucose Biosensors, Michael Hartley Freeman, Jackson R. Hall, Michael C. Leopold

Chemistry Faculty Publications

First-generation amperometric glucose biosensors incorporating alkanethiolate-protected gold nanoparticles, monolayer protected clusters (MPCs), within a xerogel matrix are investigated as model systems for nanomaterial-assisted electrochemical sensing strategies. The xerogel biosensors are comprised of platinum electrodes modified with composite films of (3-mercaptopropyl)trimethoxy silane xerogel embedded with glucose oxidase enzyme, doped with Au225(C6)75 MPCs, and coated with an outer polyurethane layer. Electrochemistry and scanning/transmission electron microscopy, including cross-sectional TEM, show sensor construction, humidity effects on xerogel structure, and successful incorporation of MPCs. Analytical performance of the biosensor scheme with and without MPC doping of the xerogel is determined from direct glucose injection during …

Combination And Applications Of Time-Resolved Surface Plasmon Resonance Spectroscopy And Electrochemical Methods, Yu Bao, Yan Mao, Wei Wang, Zheng-Gang Li, Li Niu

Journal of Electrochemistry

Electrochemical-surface plasmon resonance (EC-SPR) technique, developed in recent years, is a new technology which combines time-resolved surface plasmon resonance spectroscopy and electrochemical methods. Surface plasmon resonance (SPR) is a physical phenomenon generated by optical coupling using a metallic thin film and is very sensitive to optical analysis. The principles of SPR and EC-SPR are briefly introduced and the applications of the combination of SPR spectroscopy with electrochemical techniques are reviewed in this paper. This new technology has been widely used in such research areas as reaction dynamics, biochemical sensors, electrode/electrolyte interfaces, kinetic parameters and bimolecular interactions.

An In Situ Ftir Spectroelectrochemical Study On Methanol Oxidation At Pt-Mo2C/Gc Catalyst, Hai-Ping Huang, Xi-Yu Yao, Pei-Kang Shen

Journal of Electrochemistry

A 40% Pt on Mo₂C/GC catalyst has been prepared by ion exchange method. The mechanism of methanol electrooxidation on Pt-Mo₂C/GC and commercial Pt/C catalysts in acidic media was studied by cyclic voltammetry, XRD measurements and in-situ Fourier transform infrared spectroelectrochemistry. The results revealed that the Pt nanoparticles were uniformly dispersed on Mo₂C/GC with an average particle size of 3 nm. The cyclic voltammetric and chronopotentiometric experiments indicated that Pt-Mo₂C/GC catalyst exhibited a better performance for methanol oxidation than that of Pt/C in acid solution. A negative shift over 90 mV of the …

Utilizing Nmr Spectroscopy And Molecular Docking As Tools For The Structural Determination And Functional Annotation Of Proteins, Jaime Stark

Department of Chemistry: Dissertations, Theses, and Student Research

With the completion of the Human Genome Project in 2001 and the subsequent explosion of organisms with sequenced genomes, we are now aware of nearly 28 million proteins. Determining the role of each of these proteins is essential to our understanding of biology and the development of medical advances. Unfortunately, the experimental approaches to determine protein function are too slow to investigate every protein. Bioinformatics approaches, such as sequence and structure homology, have helped to annotate the functions of many similar proteins. However, despite these computational approaches, approximately 40% of proteins still have no known function. Alleviating this deficit will …

Preliminary Simulation Study On Classification Of Large Molecules By Newly Designed Cascade Type Differential Mobility Analyzer (Ctdma), Chenxi Zhu

Student Theses and Dissertations

Differential mobility analyzer (DMA), coupled with other instrumentation analyzers, such as mass spectrometry (MS), can classify size, masses and shapes by their different gas-phase electrophoretic mobility. In order to obtain the high resolution in classifying large particles (50 kD ~ 1 MD), our laboratory designed several versions of cylindrical cascade type differential mobility analyzers (CTDMA). Because CTDMAs consist of two cylindrical particle classifiers in one housing, target particles are guided through "gaps" and "stairs", a unique feature to this new particle classification device. Two modes of operation--outward cross flow mode and no-cross flow mode--both reduce the flow rate in the …

Overexpression Of Human Fatty Acid Transport Protein 2/Very Long Chain Acyl-Coa Synthetase 1 (Fatp2/Acsvl1) Reveals Distinct Patterns Of Trafficking Of Exogenous Fatty Acids, Elaina M. Melton, Ronald Cerny, Concetta C. Dirusso, Paul N. Black

Ronald Cerny Publications

In mammals, the fatty acid transport proteins (FATP1 through FATP6) are members of a highly conserved family of proteins, which function in fatty acid transport proceeding through vectorial acylation and in the activation of very long chain fatty acids, branched chain fatty acids and secondary bile acids. FATP1, 2 and 4, for example directly function in fatty acid transport and very long chain fatty acids activation while FATP5 does not function in fatty acid transport but activates secondary bile acids. In the present work, we have used stable isotopically labeled fatty acids differing in carbon length and saturation in cells …

High-Pressure Cryogelation Of Nanosilica And Surface Properties Of Cryosilicas, V M. Gun'ko, V V. Turov, V I. Zarko, G P. Prykhod'ko, O S. Remez, R Leboda, J Skubiszewska-Zieba, E M. Pahklov, Jonathan Blitz

Faculty Research and Creative Activity

Silica cryogels (cryosilicas) in a powder state were synthesized with different concentrations of fumed silica A-300 (CA-300 = 5-20 wt.%), sonicated in aqueous suspension, then frozen at -14 oC at different pressures in a high-pressure stainless steel reactor (a freezing bomb), and dried in air at room temperature. To analyze the effects of low temperature and high pressure, samples were also prepared at -14 oC or room temperature and standard pressure. The structural and adsorption properties of the powder materials were studied using nitrogen adsorption, high-resolution transmission electron microscopy, infrared spectroscopy, thermogravimetry, low-temperature 1H NMR spectroscopy and thermally stimulated depolarization …

High-Pressure Cryogelation Of Nanosilica And Surface Properties Of Cryosilicas, V Gun'ko, V Turov, V Zarko, G Prykhod'ko, O Remez, R Leboda, J Skubiszewska-Zieba, E Pahklov, Jonathan Blitz

Faculty Research and Creative Activity

Silica cryogels (cryosilicas) in a powder state were synthesized with different concentrations of fumed silica A-300 (CA-300 = 5-20 wt.%), sonicated in aqueous suspension, then frozen at -14 oC at different pressures in a high-pressure stainless steel reactor (a freezing bomb), and dried in air at room temperature. To analyze the effects of low temperature and high pressure, samples were also prepared at -14 oC or room temperature and standard pressure. The structural and adsorption properties of the powder materials were studied using nitrogen adsorption, high-resolution transmission electron microscopy, infrared spectroscopy, thermogravimetry, low-temperature 1H NMR spectroscopy and thermally stimulated depolarization …

Probing The Bifunctional Catalytic Activity Of Ceria Nanorods Towards The Cyanosilylation Reaction, Gonghua Wang, Lu Wang, Xiang Fei, Yunyun Zhou, Renat F. Sabirianov, Wai-Ning Mei, Chin Li Cheung

Department of Chemistry: Faculty Publications

Ceria nanorods were demonstrated to be an active, bifunctional catalyst for the cyanosilylation of aldehydes. The catalytic activity of ceria was shown to be positively correlated with a decrease in the coordination numbers of neighbouring oxygen atoms around cerium atoms in the catalyst. Chemisorption and density functional theory studies suggested that the coordinatively unsaturated cerium sites exposed by the surface oxygen vacancy defects functioned as Lewis acid sites and the neighbouring oxygen atoms behaved as Lewis base sites in the catalytic cycle.

A Facile, Low-Cost Route For The Preparation Of Calcined Porous Calcite And Dolomite And Their Application As Heterogeneous Catalysts In Biodiesel Production, Rui Wang, Hu Li, Fei Chang, Jiafeng Luo, Milford A. Hanna, Daoyang Tan, Deyu Hu, Yuping Zhang, Baoan Song, Song Yang

Department of Chemistry: Faculty Publications

Despite their potential for biodiesel synthesis, directly calcined minerals rich in magnesium/calcium carbonates are used at the expense of large amounts of the catalyst, high alcohol loading, long processing times, and severe conditions. We report a facile and low-cost route for preparing calcined porous calcite (CPC) and dolomite (CPD) via simple thermal decomposition of the reaction mixtures of natural calcite and dolomite with stearic acid. CPC and CPD, both of which have porous structures, were compared with previously reported catalysts and examined as promising heterogeneous base catalysts under mild conditions. A 40% increase in conversion through CPC and CDC was …

Re2o7-Catalyzed Reaction Of Hemiacetals And Aldehydes With O-, S-, And C-Nucleophiles, Wantanee Sittiwong, Michael W. Richardson, Charles E. Schiaffo, Thomas J. Fisher, Patrick H. Dussault

Department of Chemistry: Faculty Publications

Re(VII) oxides catalyze the acetalization, monoperoxyacetalization, monothioacetalization and allylation of hemiacetals. The reactions, which take place under mild conditions and at low catalyst loadings, can be conducted using hemiacetals, the corresponding O-silyl ethers, and, in some cases, the acetal dimers. Aldehydes react under similar conditions to furnish good yields of dithioacetals. Reactions of hemiacetals with nitrogen nucleophiles are unsuccessful. 1,2-Dioxolan-3-ols (peroxyhemiacetals) undergo Re(VII)-promoted etherification but not allylation. Hydroperoxyacetals (1-alkoxyhydroperoxides) undergo selective exchange of the alkoxide group in the presence of either Re₂O₇ or a Brønsted acid.

Stress Reduction For Pillar Filled Structures, Rebecca J. Nikolic, Adam Conway, Qinghui Shao, Lars Voss, Chin Li Cheung, Mushtaq A. Dar

Department of Chemistry: Faculty Publications

According to one embodiment, an apparatus for detecting neutrons includes an array of pillars, wherein each of the pillars comprises a rounded cross sectional shape where the cross section is taken perpendicular to a longitudinal axis of the respective pillar, a cavity region between each of the pillars, and a neutron sensitive material located in each cavity region.

Iodonium Cyclophanes For Secure Arene Functionalization, Stephen Dimagno

Department of Chemistry: Faculty Publications

This disclosure relates to compounds, reagents, and methods useful in the synthesis of aryl fluorides, for example, in the preparation of 18F labeled radiotracers. For example, this disclosure provides universal “locked” aryl substituents that result in StereoElectronic Control of Unidirectional Reductive Elimination (SECURE) from diaryliodonium salts. The reagents and methods provided herein may be used to access a broad range of compounds, including aromatic compounds, heteroaromatic compounds, amino acids, nucleotides, and synthetic compounds.

Single Transcriptional And Translational Preq1 Riboswitches Adopt Similar Pre-Folded Ensembles That Follow Distinct Folding Pathways Into The Same Ligand-Bound Structure, Krishna C. Suddala, Arlie J. Rinaldi, Jun Feng, Anthony M. Mustoe, Catherine D. Eichhorn, Joseph A. Liberman, Joseph E. Wedekind, Hashim M. Al-Hashimi, Charles L. Brooks Iii, Nils G. Walter

Department of Chemistry: Faculty Publications

Riboswitches are structural elements in the 50 untranslated regions of many bacterial messenger RNAs that regulate gene expression in response to changing metabolite concentrations by inhibition of either transcription or translation initiation. The preQ₁ (7-aminomethyl-7-deazaguanine) riboswitch family comprises some of the smallest metabolite sensing RNAs found in nature. Once ligand-bound, the transcriptional Bacillus subtilis and translational Thermoanaerobacter tengcongensis preQ₁ riboswitch aptamers are structurally similar RNA pseudoknots; yet, prior structural studies have characterized their ligand-free conformations as largely unfolded and folded, respectively. In contrast, through single molecule observation, we now show that, at nearphysiological Mg²⁺ concentration and pH, …

Development Of Matrix Assisted Ionization Methods For Characterization Of Soluble And Insoluble Proteins From Native Environments By Mass Spectrometry, Ellen Dela Victoria Inutan

Wayne State University Dissertations

Matrix-assisted laser/desorption ionization (MALDI) and electrospray ionization (ESI) have made a huge impact in the analysis of biological materials. ESI has gained its popularity involving liquid based analysis, efficient fragmentation, chromatographic and electrophoretic separations but has a limitation for solubility restricted materials and surface analysis. MALDI is applicable to large biomolecule analysis and for surface methods useful for tissue imaging but is limited for structural characterization due to poor fragmentation and is ill suited for liquid based separation methods. The research presented here relates to new ionization methods that encompass the benefits of ESI and MALDI. These novel ionization methods …

Investigation Of Dopamine Dynamics In Bdnf+/- Mice Using In Vivo Microdialysis And Electrochemical Analysis Of Purine And Monoamine Molecules Using A Boron-Doped Diamond Electrode, Johnna A. Birbeck

Wayne State University Dissertations

The goal of the first study was to determine if a reduction in brain-derived neurotrophic factor (BDNF) levels in female mice lead to a dysregulation in their dopaminergic system. Through a series of in vivo microdialysis and slice voltammetry experiments, we have discerned that female BDNF^+/- mice are hyperdopaminergic similar to their male BDNF^+/- counterparts. The in vivo microdialysis method zero-net flux highlighted that female BDNF^+/- mice had increased extracellular dopamine (DA) levels, while stimulated regional release by high potassium potentiated DA release from vesicular mediated depolarization. Using the complementary technique of fast scan cyclic voltammetry, electrical …