Analytical Chemistry Commons^™

Electrochemical Surface-Enhanced Raman Spectroscopy—Current Status And Perspective, Bin Ren, Jian-Feng Li, Yi-Fan Huang, Zhi-Cong Zeng, Zhong-Qun Tian

Journal of Electrochemistry

Electrochemical interface is a very important interface closely related to various energy and life processes. Surface-enhanced Raman scattering was widely used in electrochemistry soon after its discovery to understand the surface bonding,configuration,and orientation of the surface species. In recent 10 years,the fast development of nanoscience and nanotechnology has offered SERS with abundant substrates and characterization methods,which has allowed impressive development of electrochemical SERS. This articles will follow the time line to make systematically overview of SERS on Au and Ag,thin-layer transition-metal SERS,pure transition metal SERS,core-shell SERS and those methods for studying single crystal surfaces,including gap-mode SERS, TERS and SHINERS. Emphasis …

Density Functional Theory Studies Of Surface-Enhanced Raman Spectroscopy In Electrochemical Interfaces, Liu-Bin Zhao, De-Yin Wu, Bin Ren, Zhong-Qun Tian

Journal of Electrochemistry

Quantum chemical density functional theory and Raman scattering theory were used to study the bonding mechanism and surface-enhanced Raman spectroscopy of pyridine adsorbed on transition metals (Ⅷ group) and coinage metals (IB group) . SERS studies of pyridine-metal systems have been reviewed. Chemical bonding mechanism as well as photo-driven charge transfer mechanism was considered to investigate the vibrational frequency shift and the enhancement of SERS intensity in electrochemical interfaces. Our theoretical results can be used to interpret the SERS phenomena dependent on metals,excitation wavelengths,and applied potentials.

Electrochemical Sers Studies On The Adsorption Of Benzoimidazole And Derivative In Nonaqueous Solution, Ya-Xian Yuan, Feng-Zhu Yang, Wei Liu, Ping-Jie Wei, Jian-Lin Yao, Ren-Ao Gu

Journal of Electrochemistry

The surface adsorption of benzoimidazole (BIMH) and 2-mercaptobenzimidazole(MBI) was investigated by electrochemical in-situ surface enhanced Raman spectroscopy (SERS) and direct electrochemical synthesis on Cu electrode. The influence of the neutral ligand of triphenylphosphine (pph₃) on the adsorption and surface coordination of BIMH and MBI were investigated respectively. BIMH interacted with metal surface by the neutral molecule to form chemical adlayer in the extremely negative potential,while it adsorbed onto metal surface through the N atoms to form a polymer film which may suppress the corrosion of the metal. The introduction of pph₃ destroyed the film formation of BIMH …

Full Multiple Scattering Analysis Of Xanes At The Cd L 3- And O K- Edges In Cdo Films Combined With A Soft-X-Ray Emission Investigation, I. N. Demchenko, J. D. Denlinger, M. Chernyshova, K. M. Yu, D. T. Speaks, P. Olalde-Velasco, Oliver Hemmers, W. Walukiewicz, A. Derkachova, K. Lawniczak-Jablonska

Environmental Studies Faculty Publications

X-ray absorption near edge structure (XANES) at the cadmium L3 and oxygen K edges for CdO thin films grown by pulsed laser deposition method, is interpreted within the real-space multiple scattering formalism, FEFF code. The features in the experimental spectra are well reproduced by calculations for a cluster of about six and ten coordination shells around the absorber for L3 edge of Cd and K edge of O, respectively. The calculated projected electronic density of states is found to be in good agreement with unoccupied electronic states in experimental data and allows to conclude that the orbital character of the …

Spectroelectrochemical Studies Of Metalloporphyrins In Room Temperature Ionic Liquid, Yong Soo Hoo

Master's Theses (2009 -)

The oxidation/reduction reactions of porphyrins and metalloporphyrins play an important role in medicinal, industrial and biochemical reactions. Metalloporphyrins are particularly useful as potential catalysts for a variety of processes including catalytic oxidations. The unique properties of metalloporphyrins make them good candidates as electrocatalysts for fuel cells. Metalloporphyrins also play some important roles in biological functions.

By incorporating spectroscopic experiments such as UV-visible or infra-red spectroscopy along with electrochemical experiments such as cyclic voltammetry, one is able to determine the structural changes of the molecule when oxidation or reduction reaction is carried out.

Perfluoroalkyl Phosphonic And Phosphinic Acid Electrolytes For Proton Exchange Membrane Fuel Cells, Mahesha Herath

All Dissertations

Perfluorinated sulfonic acid polymers have been considered as the state-of-art membrane materials for proton exchange membrane fuel cells. A major technical issue with these polymers is that they do not function well at temperatures above 80 °C and at low humidities. Therefore, research has been focused on developing PEM materials that can operate independent of hydration requirements. The operation of fuel cells at high temperature (e.g. 120 oC) increases fuel cell system efficiency due to faster electrode kinetics and better CO tolerance. This dissertation will describe a study of proton-transport rates and mechanisms under anhydrous and aqueous conditions using a …

Rapid Multi-Class Multi-Residue Method For The Confirmation Of Chloramphenicol And Eleven Nitroimidazoles In Milk And Honey By Liquid Chromatography Tandem Mass Spectrometry, Mark Cronly, Patrice Behan, Barry Foley, Liam Regan, Sheila Martin, Michael Doyle, Edward Malone

Articles

A confirmatory method has been developed to allow for the analysis of eleven nitroimidazoles and also chloramphenicol in milk and honey samples. These compounds are classified as A6 compounds in annex IV of council regulation 2377/90 and therefore prohibited for the use in animal husbandry. Milk samples are extracted by acetonitrile with addition of NaCl, while honey samples are first dissolved in water before a similar extraction. Honey extracts undergo a hexane wash to remove impurities. Both milk and honey extracts are evaporated to dryness and reconstituted in initial mobile phase. These are then injected onto an LC-MS/MS system and …

Measurement And Wavelet Analysis Of The Electrochemical Noise Of Rebar Steel In Simulated Concrete Pore Solution, Rong-Gang Hu, Chen-Qing Ye, Shi-Gang Dong, Chang-Jian Lin

Journal of Electrochemistry

Electrochemical noise (ECN) measurement can provide information about both corrosion rate and corrosion type while inflicting no perturbation on the studied system. The ECN data of steel rebar in SPS with different amount of Cl-were collected and treated by discrete wavelet transformation to evaluate the contribution from transients in different frequency in the overall signals. Energy distribution plot (EDP) indicated in SPS with 0.0001 mol/L NaCl, the transients with time constant between 16 ～ 32 s were found to be predominant over other processes; while in SPS with higher Cl-concentration, the trend toward active corrosion became the main process. It …

Fabrication Of Electrochemically Activated Glassy Carbon/Bismuth Film Electrodes For Sensitive Analysis Of Pb(2+) And Cd(2+), Kang Shi, Wen-Jing Wang, Kun Hu

Journal of Electrochemistry

The application of electrochemically activated glassy carbon (GC) in the in-situ preparing of bismuth film electrodes (BiFEs) to analyze Pb^{2 +} and Cd^{2 +} was investigated. The glassy carbon electrodes were electrochemically activated by either potentiostic or cyclic polarization in 1 mol·L^-1 NaOH solution. Experimental results show that employment of HCl solution as the analytical solution not only can reproducibly renew the electrochemically activated GC electrode surface with an electrochemical clear procedure, but also can greatly enhance the sensitivity of BiFes method for analysis of Pb^{2 +} and Cd^{2 +}. The test range thus …

Blocking Method In Enzyme-Amplified Amperometric Dna Biosensor, Miao He, Wei Chen, Xiong-Wei Xu, Ai-Lin Liu, Xin-Hua Lin

Journal of Electrochemistry

Non-specific absorption of enzyme and nucleotide is a main source leading to the background staining in enzyme-amplified amperometric detection of DNA. To eliminate the background staining in this system, the blocking procedure by mercapto-hexanol (MCH) and bovine serum albumin (BSA) was studied systematically. The results show that the anti-fouling effect of BSA is better than that of MCH. A simple and efficient blocking strategy employing BSA as the sole blocking reagent was established and applied in the detection of PMLRARα fusion gene in acute promyelocytic leukemia. It can effectively eliminate the background staining,shorten the pre-processing time,and achieve strong signal amplification.

A Preliminary Study In Probing Rapid Method Of Isotope 87sr/86sr Analysis By Electrospray Ionization -Quadrupole Ion Trap - Mass Spectrometry, Sheng Song

Student Theses and Dissertations

The isotope ratio 87Sr/86Sr, typically reported in geologic investigations, is obtained by direct electrospray ionization of aqueous sample containing Sr(II), Rb(I) and 18c6. At relatively high concentrations, we observed favorable formation of Sr2+(18c6)₂ and Rb+(18c6) over Sr2+(18c6) complexes. Physical separation of Sr2+(18c6)₂ and Rb+(18c6) as well as separation of Sr2+(18c6)₂ is observed by simply injecting the sample solution to ESI source using simple PEEK tubing in neutral pH. These phenomena are caused by the difference in mobility of the complexes and masked by the gas phase association reactions. ESI-QITMS successfully obtained the expected isotope distribution of Sr(II) …

Chemical Characterization Of Botanical Products: Comprehensive Speciation By Liquid Chromatography Particle Beam Mass Spectrometry, Joaudimir Castro Georgi

All Dissertations

The dietary supplement industry has expanded and many of these supplements have become an important aspect of people's everyday lives. In 1994, the U.S. Dietary Supplement Health and Education Act (DSHEA) classified numerous nutraceutical/botanical products as dietary supplements because of their beneficial medicinal properties and provided the necessary regulation to the supplement producers. Since then, the interest of the scientific community towards dietary supplements has grown intensively and numerous studies have been carried out in order to understand the chemical behavior of the active molecules in the human body. The development towards analytical methods for the quantification of the active …

Pulsed-Laser Excited Photothermal Study Of Glasses And Nanoliter Cylindrical Sample Cell Based On Thermal Lens Spectroscopy, Prakash Raj Joshi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The research in this dissertation presents Pulsed-Laser Excited photothermal studies of optical glasses and cylindrical sample cell.

First, a study of a photothermal lens experiment and the finite element analysis modeling for commercial colored glass filters is done. The ideal situation of a semiinfinite cylinder approximate model used to describe the photothermal lens experiment requires the boundary condition that there is no transfer of heat from the glass to surrounding when the glass is excited with a laser. The finite element analysis modeling for photothermal signal with coupling heat with surrounding shows the thermal heat transfer between the glass surface …

Chromatographic Studies Of Drug-Protein Binding In Diabetes, Kathryn (Krina) S. Joseph

Department of Chemistry: Dissertations, Theses, and Student Research

Drug-protein binding can have a dramatic impact on the distribution and metabolism of a drug. This manuscript describes the use of high-performance affinity chromatography to examine the binding of various compounds to human serum albumin (HSA) in normal and diabetic disease states. The first study examined the use of four coumarin compounds as possible alternatives to warfarin as a probe for Sudlow site I on HSA. High-performance affinity chromatography and immobilized HSA columns were used to compare and evaluate the binding properties of these probe candidates. It was found from this group that 4-hydroxycoumarin was the best alternative to warfarin …

Preparation And Characterization Of Extraction Chromatography Resins Using N-Donor Extractants For Trivalent Actinide And Lanthanide Separations, Christopher L. Klug

UNLV Theses, Dissertations, Professional Papers, and Capstones

Actinide and lanthanide elements exist in the geosphere and biosphere due to both natural abundances and anthropogenic activities. The investigation of the presence and transport of actinides through the environment is of great scientific interest. In order to prepare environmental samples for precise measurements, the individual actinides must be separated from the chemically similar lanthanides, and from neighboring actinides. Existing extraction chromatography resins are either poorly suited for this separation, have bleeding problems, are not reusable, or fail the CHON principle. In an effort to resolve these issues, malonamides and N-donor extractants from the BTP and BTBP classes of solvent …

Comparison Of Rna Quality From Stressed And Unstressed Recombinant Escherichia Coli, Mary Alice Salazar

All Theses

High quality, intact RNA is required for DNA microarray studies, cloning, and reverse transcriptase polymerase chain reaction (rt-PCR) analysis. There are several analytical methods used to assess the RNA quality. The RNA Integrity Number (RIN) from the Agilent Bioanalyzer is one quality control assay used to evaluate RNA. For recombinant Escherichia coli cultured under stressful conditions the RNA profiles obtained using the Agilent Bioanalyzer indicate RNA degradation; however, RNA obtained and purified in parallel from unstressed recombinant cultures indicate acceptable RNA values without significant degradation. We proposed that for stressed E. coli the RIN value is not necessarily indicative of …

A Synthetic Biological Engineering Approach To Secretion- Based Recovery Of Polyhydroxyalkanoates And Other Cellular Products, Elisabeth Linton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The costs associated with cellular product recovery commonly account for as much as 80% of the total production expense. As a specific example, significant recovery costs limit commercial use of polyhydroxyalkanoates (PHA), which comprise a class of microbially-accumulated polyesters. PHAs are biodegradable compounds that are of interest as a sustainable alternative to petrochemically-derived plastics. Secretion-based recovery of PHAs was studied to decrease PHA production costs. Type I and II secretory pathways are commonly used for the translocation of recombinant proteins out of the cytoplasm of E. coli. Proteins were targeted for translocation using four signal peptides (HlyA, TorA, GeneIII, …

Field And Smog Chamber Studies Of Agricultural Emissions And Reaction Products, Derek J. Price

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Agricultural emissions are an important contributor to atmospheric aerosol. These emissions include nitrogen containing organic compounds, primarily as amines, which have not been well investigated to date. Although there have been several studies that have looked at the emission of gas phase amines, there are only a few studies that have focused on ambient amine-based aerosol. There have also only been a handful of smog chamber studies that have investigated amine aerosol chemistry. Kinetic studies have looked at the reactions of amines with OH and ozone. However, amine reactions with nitrate radical (NO₃) are not well understood. Several …

Analysis Of Ammonia And Volatile Organic Amine Emissions In A Confined Poultry Facility, Hanh Hong Thi Dinh

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The National Air Emission Monitoring Study (NAEMS) project was funded by the Agricultural Air Research Council (AARC) to evaluate agricultural emissions nationwide. Utah State University (USU) is conducting a parallel study on agricultural emissions at a Cache Valley poultry facility. As part of this parallel study, samples of animal feed, eggs and animal waste were collected weekly from three manure barns (designated: manure barn, barn 4 - manure belt and barn 5 - high rise) from May 2008 to November 2009.

These samples were analyzed to determine ammonia content, total Kjeldahl nitrogen content and ammonia emission. The yearly average calculated …

Molecular Characterization Of The Soluble Fraction Of Atmospheric Particulate Matter Obtained By Chemical Oxidation With Nitric Acid, Amanda Susan Priest

Chemistry & Biochemistry Theses & Dissertations

The availability of information regarding the composition of ambient atmospheric particulate matter and the transformations that these compounds may undergo upon atmospheric transit is surprisingly absent. Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry is used in this study to rapidly evaluate the composition of the water-soluble organic fraction of standard and collected atmospheric particulate matter samples, and the changes that these mixtures undergo upon oxidation with nitric acid. The standard samples include representative particulate matter collected over the course of a year in Washington, D.C. and particulate matter from the exhaust of a diesel-powered engine. The collected sample …