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Sobocinski, Raymond Louis. "Electrochemical and Raman spectroscopic investigations of in situ and emersed silver-alcohol electrochemical interfaces." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185476.
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The overall goal of this research is to characterize the potential-dependent structure and composition of the alcohol-Ag electrochemical interface. The approach involves the use of a variety of electrochemical and spectroscopic tools to arrive at a consistent model for a series of straight-chain alcohols (methanol, ethanol, 1-propanol, and 1-pentanol) at Ag electrodes. There are essentially four areas of investigation presented in this dissertation. The first portion of this work has been directed at the development of charge coupled device detection in Raman spectroscopy so that many of the interface investigations could be performed. The advantages and limitations of these detectors in Raman spectroscopy are addressed. The second area involves the characterization of in-situ alcohol-Ag electrochemical interfaces using Raman spectroscopy and associated surface selection rules for the evaluation of solvent orientation and bonding. Since the series of alcohols offers a systematic variation in solvent properties, these studies provide substantial insight regarding some of the chemical interactions which can dictate orientation. The development of emersed electrode technologies is also presented as a means to improve selectivity for surface molecular species over bulk molecular species. The utility of this approach is demonstrated for a variety of straight-chain alcohols at both rough and smooth Ag electrodes. Conditions for emersing the molecular interface, intact, under potential control are presented. Finally, double layer capacitance measurements are performed to offer additional insight regarding alcohol solvent structure and interfacial composition as a function of electrode potential. In addition, capacitance-potential plots are used along with the Hurwitz-Parsons analysis to determine absolute surface coverage of Br⁻ as a function of electrode potential. These results are correlated with the Raman spectroscopic results to obtain a consistent model for the structure and composition of the alcohol-Ag electrochemical interface.
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Song, Peng. "Microengineered electrochemical reactors." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709449.
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Alvarez, de Eulate Diaz de San Martin Eva Maria. "Electrochemical studies toward proteomic analysis." Thesis, Curtin University, 2014. http://hdl.handle.net/20.500.11937/702.
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This thesis provides the basis for a label-free bioanalytical platform using electrochemical analysis at liquid –liquid interfaces. The possibility to detect biomolecules such as proteins in a label-free manner via adsorption and ion-transfer was achieved. Several pre-treatment steps used in proteome analysis, such as protein pre-concentration and digestion, were studied. The results demonstrate the promise of this strategy for the detection and identification of proteins.
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Parrilla, Pons Marc. "New Electrochemical Sensors for Decentralized Analysis." Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/396297.
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Nous sensors electroquímics per a analisis decentralitzats és una tesis que emmarca diferents aspectes del desenvolupament de sensors potenciomètrics, des de la seva fabricació, el diseny adequat, i finalment, la seva aplicabilitat en escenaris reals. En el context actual, l'evolució de la tecnologia, especialment l'aparició a nivell global d'internet, i la disponibilitat d'aquesta a baix cost han permès la creació d'eines que ens permeten connectar el món físic i, en el cas d'aquesta tesis, el món químic a la xarxa. Aquesta connexió aporta un nou grau dins l'escala de valor per a la societat actual. Concretament, aquesta aportació tecnològica va adreçada a superar els nous reptes de l'actualitat, com poden ser la sostenibilitat del sistema sanitari a causa de l'embelliment de la societat, el control medioambiental, així com també mantenir la seguretat per a la societat del benestar del futur. Així doncs, aquesta tesis presenta solucions efectives per al desenvolupament d'eines de captació d'informació que serviràn per nudrir a la societat de major coneixement. Conseqüentment, produint nous negocis al voltant, de la fabricació, processament i creació de valor entorn a aquestes dades. La recerca i desenvolupament de sensors potenciomètrics integrats a la roba per detectar els nivells d'electròlits i sensors senzills de paper per a la determinació de biomolècules, com la glucosa, són alguns dels objectius aconseguits en aquesta tesis. A més a més, sensors integrats en globus permeten l'estudi de les seves propietats mecàniques i electroquímiques, així com també, aporten noves solucions a problemes reals. Totes aquestes aplicacions serveixen de portals de captació d'informació química cap a la integració dins la nova societat de la informació.Nuevos sensores electroquímicos para analisis decentralizados es una tesis que enmarca diferentes aspectos del desarrollo de sensores potenciométricos, desde su fabricación, el diseño adecuado, i finalmente, su aplicabilidad en escenarios reales. En el contexto actual, la evolución de la tecnología, especialmente la aparición a nivel global de internet, y la disponibilidad de esta a bajo coste han permitido la creación de herramientas que nos permiten conectar el mundo físico y, en el caso de esta tesis, el mundo químico a la red. Esta conexión aporta un nuevo grado dentro la escala de valor para la sociedad actual. Concretamente, esta aportación tecnológica va dirigida a superar los nuevos retos de la actualidad, como pueden ser la sostenibilidad del sistema sanitario a causa del envejecimiento de la poblacion, el control medioambiental, así como también mantener la seguridad para la sociedad del bienestar del futuro. Entonces, esta tesis presenta soluciones efectivas para el desarrollo de herramientas de captación de información que servirán para nutrir a la sociedad de un mayor conocimiento. Por consiguiente, produciendo nuevos negocios alrededor, de la fabricación, procesado i creación de valor en los datos obtenidos. La investigación y desarrollo de sensores potenciométricos integrados en la ropa para detectar los niveles de electrolitos y sensores simples en papel para la determinación de biomoléculas, como la glucosa, son algunos de los objetivos conseguidos en esta tesis. Además, sensores integrados en globos permiten el estudio de sus propiedades mecánicas y electroquímicas, así como, aportando nuevas soluciones a problemas reales. Todas estas aplicaciones sirven de portales de captación de información química hacia la integración dentro de la nueva sociedad de la información.
ew Electrochemical Sensors for Decentralized Analysis is a thesis that wisely discuss the developments of potentiometric sensors, from the fabrication step, the use of a suitable design, to the applicability in real scenarios. Nowadays, the evolution of technology, specially the creation of the global internet network, and the low-cost availability of such technology have allowed the development of tools that connect the physical world and, addressed in this thesis, the chemical world into the network. This connection adds a new level in the value chain for the present society. Precisely, this technology approach is focus on circumvent new present challenges of society. For instance, sustainability of the healthcare system caused by the population aging, environmental monitoring, as well as, keep security and safety to the welfare of society of the future. Therefore, this thesis presents successful solutions for the development of tools to gather chemical information. This information will nurture society with high-value knowledge. Accordingly, new business development from, sensing products, data treatment and information management are going to be created. Research and development of potentiometric sensors integrated into garments for electrolyte detection and simple sensors built in paper for biomolecules determination, such as glucose, and liquid monitoring, such as sweat, are some of the accomplished objectives from this thesis. Furthermore, balloon-embedded sensors allow the study of the mechanical and electrochemical properties of the electrodes, as well as, contributing with new solutions to real problems. All the applications developed in this thesis are utilized as gateways for chemical information acquisition towards the integration into the new information society.
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Chu, Kevin Taylor. "Asymptotic analysis of extreme electrochemical transport." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33669.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2005.Includes bibliographical references (p. 237-244).
In the study of electrochemical transport processes, experimental exploration currently outpaces theoretical understanding of new phenomena. Classical electrochemical transport theory is not equipped to explain the behavior of electrochemical systems in the extreme operating conditions required by modern devices. In this thesis, we extend the classical theory to examine the response of two electrochemical systems that form the basis for novel electrochemical devices. We first examine the DC response of an electrochemical thin film, such as the separator in a micro-battery, driven by current applied through reactive electrodes. The model system consists of a binary electrolyte between parallel-plate electrodes, each possessing a compact Stern layer which mediates Faradaic reactions with Butler-Volmer kinetics. Our analysis differs from previous studies in two significant ways. First, we impose the full nonlinear, reactive boundary conditions appropriate for electrolytic/galvanic cells.
(cont.) Since surface effects become important for physically small systems, the use of reactive boundary conditions is critical in order to gain insight into the behavior of actual electrochemical thin films that are sandwiched between reactive electrodes, especially at high current densities. For instance, our analysis shows that reaction rate constants and the Stern-layer capacitance have a strong influence on the response of the thin film. Second, we analyze the system at high current densities (far beyond the classical diffusion-limited current) which may be important for high power-density applications. At high currents, we obtain previously unknown characterizations of two interesting features at the cathode end of the cell: (i) a nested boundary layer structure and (ii) an extended space charge region. Next, we study the response of a metal (i.e., polarizable) colloid sphere in an electrolyte solution over a range of applied electric fields.
(cont.) This problem, which underlies novel electrokinetically driven microfluidic devices, has traditionally been analyzed using circuit models which neglect bulk concentration variations that arise due to double layer charging. Our analysis, in contrast, is based on the Nernst-Planck equations which explicitly allow for bulk concentration gradients. A key feature of our analysis is the use of surface conservation laws to provide effective boundary conditions that couple the double layer charging dynamics, surface transport processes, and bulk transport processes. The formulation and derivation of these surface conservation laws via boundary layer analysis is one of the main contributions of this thesis. For steady applied fields, our analysis shows that bulk concentrations gradients become significant at high applied fields and affect both bulk and double layer transport processes. We also find that surface transport becomes important for strong applied fields as a result of enhanced absorption of ions by the double layer.
(cont.) Unlike existing theoretical studies which focus on weak applied fields (so that both of these effects remain weak), we explore the response of the system to strong applied fields where both bulk concentration gradients and surface transport contribute at leading order. For the unsteady problem at applied fields that are not too strong, we find that diffusion processes, which are necessary for the system to relax to steady-state, are suppressed at leading-order but appear as higher-order corrections. This result is derived in a novel way using time-dependent matched asymptotic analysis. Unfortunately, the dynamic response of the system to large applied fields seems to introduce several complications that make the analysis (both mathematical and numerical) quite challenging; the resolution of these challenges is left for future work. Both of these problems require the use of novel techniques of asymptotic analysis (e.g., multiple parameter asymptotic expansions, surface conservation laws, and time-dependent asymptotic matching) and advanced numerical methods (e.g., pseudospectral methods, Newton-Kantorovich method, and direct matrix calculation of Jacobians) which may be applicable elsewhere.
by Kevin Taylor Chu.
Ph.D.
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Ding, Wenwu Carleton University Dissertation Chemistry. "Electrochemical hydride generation for ultratrace analysis." Ottawa, 1995.
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D'Arcy, Karen Ann. "Electrochemical methods for speciation of inorganic arsenic." PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/524.
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Arsenic is found in the environment in several oxidation states as well as in a variety of organoarsenic compounds. This situation puts additional demands on the analysis in that it is desirable to measure the amount of each species, not just all of the arsenic. The reason for this is that the different species have greatly different toxicities; of the major inorganic forms, As(III) is much more toxic than As(V). The goal of this research was to develop a convenient method for the analysis of mixtures of As(III) and As(V) at trace levels. Electroanalytical methods are inherently sensitive to oxidation states of elements and therefore are a natural choice for this problem. In fact, a method was developed some years ago for As(III) that used differential pulse polarography: the detection limit is 0.3 parts per billion (ppb). However, As(V) was not detected since in its usual form as an oxyanion it is electrochemically inactive. There are coordinate compounds formed with catechol, AsL(,n)(n = 1-3), that can be reduced at a mercury electrode, but the active species, AsL, is only a small fraction of the major species, AsL(,3), so the detection limit is only 500 ppb. Many details of the electrochemistry of this unusual compound were examined in this work. In order to improve detection limits, a method involving cathodic stripping was developed. It involves codeposition of copper with arsenic on a mercury electrode to effectively concentrate the analyte. Then the elemental arsenic is converted to arsine, AsH(,3), during a cathodic potential scan. The resulting current peak is proportional to As(III) in the absence of catechol and to the sum of As(III) and As(V) in the presence of catechol. It was observed that the current peak was considerably larger than expected and additional experiments revealed that there was evolution of hydrogen during the formation of arsine. This is rather unusual in electrochemical reactions and so some of the details of this catalyzed coreaction were examined. The result is a fortunate enhancement of detection limit so that As(v) at 40 ppb can be measured.
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Wengenack, Nancy L. "Design and testing of a computer-controlled square wave voltammetry instrument /." Online version of thesis, 1987. http://hdl.handle.net/1850/8853.
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Jagannathan, Sudhakar. "Process, structure and electrochemical." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29713.
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Thesis (Ph.D)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2009.Committee Chair: Kumar, Satish; Committee Member: Cook, Fred L.; Committee Member: Bottomley, Lawrence A.; Committee Member: Carter, William Brent; Committee Member: Yushin, Gleb. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Ismail, Iqbal M. I. "Electrochemical studies of polymer electrolytes." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242319.
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Larsson, Mariann. "Electrochemical analysis of Zinc for biodegradable applications." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121526.
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To avoid costly and risky secondary surgery after implantation, biodegradableimplants are of importance to the medical device industry. Theseshould be designed to degrade in a controlled manner, and to haverest products taken care of by the body’s internal mechanisms withoutcausing harm. Finding materials that corrodes predictably, are biocompatiblein itself and when decomposed is a great challenge. This study focused on the corrosion behaviour of zinc, which anearlier study pointed out as a promising subject for such an analysis.The properties of zinc samples were observed by electrochemical methodswhile immersed in phosphate buffered saline (PBS), Ringer solutionand human blood. Scanning electron microscopy (SEM) and energy dispersivex-ray spectroscopy (EDX) were used to characterise the structureand composition of the corrosion products. It was found that thecorrosion mechanisms are different in the three electrolytes studied. Samples immersed in Ringer solution showed a uniform corrosion,with an initial corrosion rate of 0.1 mm/yr - 0.5 mm/yr. Resultsfrom electrochemical impedance spectroscopy (EIS) suggest the corrosionproducts after time (12-24 h) correspond to a two-layer interface,interpreted as an outer diffusion controlled layer appearing first, witha homogenous layer being formed later between the metal and the initiallayer. EDX and SEM indicates that the corrosion products mainlyconsist of zinc carbonates. These findings were confirmed by FourierTransform Infrared (FTIR) spectroscopy. The zinc samples exposed to PBS solution exhibit a localized corrosion,with dendrite like structures growing out from the surface astime passes. The initial corrosion rate was determined to be somewherebetween 6 μm/yr- 22 μm/yr. The EIS model suggest that the corrosionproducts developed on the PBS exposed surface corresponds to a singleoxide layer covering the metal. The main corrosion products weredetermined to be zinc phosphates (FTIR and EDX). Human blood was used for a final set of experiments. Here the zincsamples corroded by an initial rate of 0.08 - 0.38 mm/yr. The corrosionwas uniform like the samples exposed to Ringer solution. Meanwhile,the electrochemical model (from EIS) appeared similar to the one encounteredin the PBS experiments, suggesting a single layer of corrosionproducts over the metal surface.För att undvika kostsamma och riskfyllda sekundära ingrepp är nedbrytbaraimplantat intressanta. Dessa designas för att för att kontrolleratbrytas ned och tas omhand av kroppens egna mekanismer. Den storautmaningen är att hitta material som bryts ner på ett ofarligt och förutsägbartsätt, i termer av hastighet, restprodukter och biokompatibilitet. Denna studie fokuserade på korrosionsförloppet hos zink, vilket en tidigarestudie visat vara en lämplig kandidat för denna sorts analys. Zinkprovernasegenskaper observerades med elektrokemiska metoder medan provernavar nedsänkta i/täckta av fosfatbuffrad saltlösning (PBS), Ringerlösningsamt mänskligt blod. Svepelektronmikroskopi (SEM), svenska ord för(EDX) var två metoder som användes för att undersöka strukturen ochsammansättningen av korrosionsprodukterna. Det visade sig att korrosionsmekanismenvar olika i de tre olika studerade elektrolyterna. Prover som var täckta av Ringerlösning visade homogen korrosionmed en initial korrosionshastighet på 0.1 mm/år - 0.5 mm/år. Resultatfrån den elektrokemiska impendansspektroskopin pekar mot att korrosionsprodukternaefter 12-24 h motsvarar ett två-lagers gränssnitt somkan tolkas som ett initialt (0-12 h) bildat yttre diffusionskontrolleratlager, följt av ett homogent lager som bildas mellan metallen och detinitiala lagret. EDX och SEM visar att korrosionsprodukterna till mestadelsbestår av zinkkarbonater. Dessa observationer är även styrkta avFTIR. Zinkproverna som utsattes för PBS uppvisade fläckvis korrosion,med dendrit-liknande strukturer som växte ut ur underlaget under provtiden.Initial korrosionshastighet uppmättes mellan 6 och 22 μm/år.Resultaten från EIS påvisar en elektrokemisk modell motsvarande ettenkelt oxidlager, som täcker hela den yta som exponeras för lösningen.Korrosionsprodukterna bestod huvudsakligen av zinkfosfater (FTIR, EDX).Slutligen användes människoblod i en omgång av experiment. Härkorroderade proverna initialt med en hastighet på 0.08-0.38 mm/år.Korrosionen var homogen, likt proverna som utsattes för Ringerlösning.Den elektrokemiska modellen (fastställd med EIS) överensstämde dockmed den som fanns i PBS-resultaten, med ett enkelt lager av korrosionsprodukteröver hela ytan.
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Zheng, Feng. "Advanced electrochemical analysis for complex electrode applications." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/288481.
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This thesis has investigated several complex situations that may be encountered in electrochemical studies. Three main situations have been examined, they include the formation of polymer films on electrode surfaces during measurements, a novel nanocatalyst modified electrode surfaces, and organised carbon nanotube (CNT) structures on electrode surfaces. These have been utilised for different electrochemical applications owing to their dissimilar properties. Voltammetric techniques of cyclic voltammetry (CV), square wave voltammetry (SWV) and Fourier transformed large amplitude ac voltammetry (FTACV) have been utilised to examine these reactions. Chapter 3 reports the investigation of catechol oxidation and subsequent polymerisation through crosslinking with D-glucosamine or chitosan. Hydrogel can be formed on the electrode surface during the process, which changes the viscosity of the solution and thus affects the diffusion of chemical species. This process has been examined by several voltammetric techniques. A further examination of the chemical system has also been conducted using FTACV for the first time. Chapter 4 describes the preparation of carbon microsphere supported molybdenum disulfide. The material has been utilised as electrocatalysts for hydrogen evolution reaction (HER) in acidic media, and the performance tested by traditional linear sweep voltammetry (LSV) and advanced FTACV techniques. The FTACV technique has been used for the first time for HER processes. In addition, the synthesised particles have also been used for thermal catalytic decomposition of hydrogen sulfide, which shows a significant improvement in the conversion rate over conventional examples. Chapter 5 demonstrates the direct growth of vertically aligned CNT forests on a gold electrode. The electrochemical response of the fabricated electrode has also been examined with ferrocyanide as the redox species. Furthermore, the immobilisation of anthraquinone onto CNT forest has been attempted. The fabricated electrode was utilised as a pH sensor via CV and SWV, and both indicates a well correlated pH-potential relationship in the pH range of 2 to 12. The sensor has also been assessed by the FTACV technique.
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Rusinek, Cory A. "New Avenues in Electrochemical Systems and Analysis." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490350904669695.
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Rohanifar, Ahmad. "Conductive Polymers for Electrochemical Analysis and Extraction." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1544809010837595.
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Cosgrove, Martin. "Electrochemical approaches to hydrogen peroxide monitoring." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238189.
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彭紹光 and Siu-kwong Pang. "Electrochemical reduction of oxygen in the presence of methanol." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31213558.
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Pang, Siu-kwong. "Electrochemical reduction of oxygen in the presence of methanol /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B17545705.
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Castañeda, Briones María Teresa. "Electrochemical stripping analysis and nanoparticles for affinity biosensors." Doctoral thesis, Universitat Autònoma de Barcelona, 2008. http://hdl.handle.net/10803/3277.
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En una primera parte de esta tesis fue desarrollado un nuevo electrodo a base de pasta de grafito-epoxi composite (GECE) conteniendo nitrato de bismuto [Bi(NO3)3] como precursor de bismuto incorporado [Bi(NO3)3-GECE)], como una posible alternativa para el análisis electroquímico por redisolución de metales pesados en cantidades traza. Los resultados claramente muestran las ventajas del Bi(NO3)3-GECE en combinación con la técnica de voltamperometría de redisolución anódica de onda cuadrada (SWASV) para la detección de metales pesados. Se llevaron a cabo medidas individuales y simultáneas de Pb y Cd y los resultados mostraron claramente las ventajas del Bi(NO3)3-GECE en combinación con la técnica SWASV para la detección de metales pesados. Con el uso del Bi(NO3)3-GECE construido se pueden realizar análisis rápidos y eficaces de iones de metal en cantidades traza como Pb y Cd entre otros en muestras ambientales de suelo, aguas naturales y aguas residuales. La ventaja inherente de la no necesidad de mercurio elimina muchas de las objeciones para el uso de métodos electroquímicos en la detección de tales especies en estos medios. Comparando el Bi(NO3)3-GECE con el electrodo de película de mercurio comúnmente usado y electrodo de película de bismuto desarrollado antes por nuestro grupo, el nuevo electrodo propuesto ofrece un notable funcionamiento en el análisis de metales pesados en cantidades traza, que puede ser de gran ventaja en electroquímica, contribuyendo a una aplicabilidad más amplia de técnicas electroquímicas por redisolución relacionadas con electrodos "sin mercurio". Además de aplicaciones ambientales el electrodo desarrollado basado en bismuto tendría interés especial para la aplicación en la detección de puntos cuánticos (QDs) basados en metales pesados. Tales aplicaciones están actualmente en proceso de estudio en nuestro grupo de investigación para la detección de ADN.
Las otras partes de la tesis se dedican al desarrollo de nuevos sensores de ADN y proteínas basados en la misma técnica electroquímica de redisolución y el uso de nanopartículas de oro como marcas.
Actualmente la detección electroquímica de secuencias de ADN específicas vía el evento de hibridación es una cuestión importante por lo cual diversas estrategias han sido propuestas.
Genosensores electroquímicos de afinidad basados en el marcaje con nanopartículas de oro (AuNPs) y el uso de partículas paramagnéticas (MB) como plataforma para la inmovilización de la sonda de ADN de captura también han sido desarrollados en esta tesis a fin de demostrar la inducción magnética eficaz de un nuevo electrodo de grafito-epoxi composite-magnético (M-GECE) el cual fue construido también con pasta de grafito-epoxi composite con un pequeño imán de neodimio integrado.Todos los ensayos para la detección electroquímica de la hibridación del ADN desarrollados en esta tesis fueron basados en la detección directa de las marcas de AuNPs por medio de la técnica de voltametría de pulso diferencial (DPV) usando el M-GECE donde la intensidad de la corriente de la señal generada es directamente proporcional a la cantidad de ADN en la muestra. Como también ha sido demostrado, con el sensor de ADN asistido magnéticamente, el ADN analito condujo a una muy bien definida señal mientras que esencialmente ninguna señal fue observada para el ADN no complementario.
Un nuevo inmunoensayo electroquímico sensible ha sido desarrollado, también basado en AuNPs como marca y MB como plataforma. El método fue evaluado para un inmunoensayo heterogéneo no competitivo de una IgG humana como proteína modelo. La detección electroquímica fue llevada a cabo en la misma forma que lo fue para ADN.
La detección electroquímica de marcas de AuNPs en biosensores de afinidad usando métodos de redisolución permite el estudio detallado de la hibridación de ADN así como también inmuno-reacciones con interés en aplicaciones relacionadas con genosensores o inmunosensores. Los métodos electroquímicos usados para la detección de AuNPs como marca pueden ser muy prometedores tomando en cuenta su sensibilidad alta, límite de detección bajo, selectividad, simplicidad, bajo coste, y disponibilidad de instrumentos portátiles.
Como conclusión final, las estrategias de análisis electroquímico de ADN y proteínas fueron demostradas con éxito y debido a los resultados prometedores su uso en muestras reales es viable. Tales biosensores de ADN e inmunosensores dan lugar a un enorme potencial de aplicación principalmente para diagnóstico clínico y monitoreo ambiental entre otros campos.
In the first part of this thesis a new graphite-epoxy composite electrode containing bismuth nitrate [Bi(NO3)3-GECE)], as built-in bismuth precursor as a possible alternative for electrochemical stripping analysis of trace heavy metals has been developed. Individual and simultaneous measurements of Pb and Cd were carried out and the results clearly showed the advantages of the Bi(NO3)3-GECE in combination with square wave anodic stripping voltammetry (SWASV) technique for heavy metals detection. Fast and effective analyses of trace metal ions such as Pb and Cd among others in environmental samples of soil, natural waters and effluents can be carried out by using the new Bi(NO3)3-GECE constructed. The inherent advantage of no necessity of mercury removes many of the objections for the use of the developed sensor.
When comparing the Bi(NO3)3-GECE with the commonly used mercury film electrode and previously developed bismuth film electrode, the newly proposed electrode offers a remarkable performance in analysis of trace heavy metals, which can be advantageous in electrochemical, hence contributing to the wider applicability of electrochemical stripping techniques in connection with "mercury-free" electrodes. Beside environmental applications the developed bismuth based electrode would have special interest for application to heavy metal based quantum dots. Such applications are currently in the studying process at our research group for DNA detection.
The other parts of the thesis are dedicated to the application of electrochemical stripping analysis in connection to gold nanoparticles for DNA and protein detection.
Currently the electrochemical detection of specific DNA sequences via hybridization event is an important issue by which diverse strategies have been proposed. Affinity electrochemical genosensors based on labelling with gold nanoparticles (AuNPs) and the use of paramagnetic beads (MB) as platform for the immobilization of capture DNA probe have been also developed in this thesis in order to demonstrate the effective magnetic triggering of a new magnetic-graphite epoxy composite electrode (M-GECE) which was constructed with graphite-epoxy composite paste, with a small neodymium magnet integrated.
All the assays for the DNA hybridization electrochemical detection developed in this thesis were based on the direct detection of AuNPs labels (anchored onto the M-GECE) by means of differential pulse voltammetry (DPV). The intensity of the generated current is directly proportional to the amount of DNA at the sample. As also has been demonstrated, with this magnetically assisted DNA sensor, target DNA leaded to very well defined signal whereas essentially no signal was observed for non-complementary DNA.
By the other side a novel, sensitive electrochemical immunoassay has been also developed based in AuNPs as label and MB as platform. The method was studied and evaluated for a noncompetitive heterogeneous immunoassay of a human IgG as a model protein. The electrochemical detection was carried out in the same way that as for DNA.
The electrochemical detection of AuNPs labels in affinity biosensors using stripping methods allows the detailed study of DNA hybridization as well as immunoreactions with interest in genosensor or immunosensor applications. The developed detection methodologies may be very promising taking into account their high sensitivity, low detection limit, selectivity, simplicity, low cost, and availability of portable instruments.
As final conclusion, the DNA and protein electrochemical analysis strategies were successfully demonstrated and according to the promising results obtained its use for real samples is viable. Such DNA biosensors and immunosensors hold an enormous application potential principally for clinical diagnostic and environmental monitoring among other fields.
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Delcourt-Lancon, Alice. "Electrochemical analysis supported by macro and microelectrode array." Thesis, Durham University, 2011. http://etheses.dur.ac.uk/3570/.
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The purpose of this project was to investigate cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analytical techniques for enantioselective sensing at both a macroelectrode and a microelectrode array. The scale of the electrochemical cell was reduced from macro to micro dimensions to improve both the electroanalytical detection and the efficient use of chemicals. A microdevice was fabricated using photolithography and plasma bonding and consisting of a microelectrode array (MEA) of 306 microelectrodes, each with a diameter of 45 µm supported by a polydimethylsiloxane (PDMS) slab engraved with microfluidic channels. The electroanalytical performances of the microdevice were characterised using cyclic voltammetry and it was established that the metallisation process influenced the surface roughness of the electrode, and also affected the final response of the array. The microdevice was used for flow injection analysis using chronoamperometry and provided the capability to detect small changes of analyte concentration. The selective electro-oxidation of phenylethanol catalysed by TEMPO and (-)-sparteine at a macroelectrode and MEA was investigated. The CV analysis showed a reproducible selective oxidation in favour of the (-)-phenylethanol enantiomer. The performances of the electrodes were enhanced to improve their enantioselective capability, and to extend their application to biosensors by functionalising their surface with Self-Assembled Monolayers (SAM). The electrodes were modified with glutathione and cysteine chiral molecules to investigate their ability to recognise the proline enantiomers using EIS analysis. The electron transfer rate of the ferricyanide analyte at the cysteine monolayer was less in the presence of D proline than it was in the presence of L-proline, indicating the selective penetration of the enantiomer through the monolayer. The properties of the macroelectrode and MEA were extended to biological applications by modifying their surfaces with thiolated single stranded DNA.
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Bagley, Gillian. "The measurement and the analysis of electrochemical noise." Thesis, University of Manchester, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488277.
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Scullion, Stanley Paul. "Amperometric monitoring of nitrate and phosphate." Thesis, Loughborough University, 1989. https://dspace.lboro.ac.uk/2134/26816.
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Methods are presented here for the determination of nitrate by electrochemical techniques. The reaction of nitrate with various organic reagents was studied by differential pulse polarography and a method described based on the nitration of benzoic acid. A rectilinear response was obtained over a 10-6 to 5x10-3M concentration range with reproducibility of < 2% at higher nitrate concentrations.
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Limson, Janice Leigh. "Electrochemical studies of metal-ligand interactions and of metal binding proteins." Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1018239.
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Electrochemical methods were researched for the analysis of metals, proteins and the identification of metal binding proteins. Adsorptive cathodic stripping voltamrnetry for metal analysis combines the inherent sensitivity of electrochemical techniques with the specificity of ligands for the nonfaradaic preconcentration of analytes at the electrode. The utility of catechol, resorcinol, 4-methylcatechol and 4-t-butylcatechol as ligands was explored for the sensitive analysis of copper, bismuth, cadmium and lead on a mercury film glassy carbon electrode. Metal complexes of lead, copper and bismuth with resorcinol showed the largest increase in current with increase in metal concentration, whereas complexes of these metals with 4-t-butylcatechol showed the lowest current response. Cadmium showed the highest current responses with 4-methylcatechol. The four metals could be determined simultaneously in the presence of resorcinol, although considerable interference was observed between bismuth and copper. The electroanalysis of cysteine and cysteine containing proteins at carbon electrodes are impaired by slow electron transfer rates at carbon electrodes, exhibiting high overpotentials, greater than 1 V vs Ag! Agel. Metallophthalocyanines have been shown to promote the electrocatalysis of cysteine at lowered potentials. Chemical modification of electrodes with appropriate modifiers is a means of incorporating specificity into electroanalysis, with applications in electrocatalysis. A glassy carbon electrode was modified by electrodeposition of cobalt (II) tetrasulphophthalocyanine [Co(II)TSPct to produce a chemically modified glassy carbon electrode (CMGCE). The CoTSPc-CMGCE catalysed the oxidation of cysteine in the pH range 1 to 10. The significance of this electrode is an application for analysis of proteins at biological pH's. A biscyanoruthenium(II) phthalocyanine CMGCE catalysed the oxidation of cysteine at 0.43 V vs Ag/AgCl a significant lowering in the overpotential for the oxidation of cysteine. Metallothionein, a metal binding protein, is believed to be involved in metal homeostasis and detoxification in the peripheral organs of living systems. A method for the quantitative determination of this protein utilising its high cysteine content was presented. At pH 8.4 Tris-HCl buffer, and using a CoTSPc-CMGCE modified by electrodeposition of the modifier, the anodic peaks for the oxidation of metallothionein was observed at 0. 90 V vs Ag/ AgCI. Ferredoxin is a simple iron-sulphur protein. One tenth of its residues are cysteine. Ferredoxin is involved in simple electron transfer processes during photosynthesis and respiration. Electrochemical studies of spinach ferredoxin were conducted at a CoTSPc-CMGCE. Anodic currents for the oxidation of the cysteine fragment of ferredoxin was observed at 0.85 V vs Ag/AgCl in HEPES buffer at pH 7.4, representing a new method for analysis of this protein. Voltammetric studies of its ferric/ferrous transition have shown quasi-reversible waves atE~ -0.62 V vs Ag/AgCl only in the presence of promoters. At a CoTSPc-CMGCE, a cathodic wave attributed to the reduction of Fe(III)/Fe(II) was observed at Epc -0.34 V vs Ag/AgCl. This represents an alternative method for voltammetric studies of the ferric/ferrous transition at significantly lowered potentials. Melatonin, a pineal gland hormone functions m setting and entraining circadian rhythms and in neuroprotection as a free radical scavenger and general antioxidant. Using adsorptive cathodic stripping voltammetry, the binding affinities of melatonin, serotonin and tryptophan for metals, were measured. The results showed that the following metal complexes were formed: aluminium with melatonin, serotonin and tryptophan; cadmium with melatonin and tryptophan; copper with melatonin and serotonin; iron (III) with melatonin and serotonin; lead with melatonin, tryptophan and serotonin, zinc with melatonin and tryptophan and iron (II) with tryptophan. The studies suggest a further role for melatonin in the reduction of free radical generation and in metal detoxification and may explain the accumulation of aluminium in Alzheimer's disease.
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Zhang, Li Qun. "Square-wave voltammetric stripping detection for flow injection analysis and chromatography." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/26024.
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Shi, Kang. "Electrochemical pretreatment of carbon electrodes and the electroanalytical applications." HKBU Institutional Repository, 2000. http://repository.hkbu.edu.hk/etd_ra/271.
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Witting, Paul Kenneth. "Chemical, electrochemical and spectroelectrochemical behaviour of polycyclic nitroaromatics." Thesis, The University of Sydney, 1993. https://hdl.handle.net/2123/26629.
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A range of dinitro-9,10-ethano-9,10-dihydroanthracenes were prepared in order to determine the degree of delocalisation of electron density in their radical anions. Electrochemical and spectroelectrochemical studies of the radical anions formed from these dinitro compounds showed that the isolated nitroaromatic groups are communicating electronically. The greatest communication occurred when the bridgehead group was electron withdrawing in nature and when the nitro groups and the bridgehead substituent were in the 2, 7 and 9 configurations, respectively.
The series of substitution reactions between 2-nitro-9,10-diiodo-9,10-ethano9,10-dihydroanthracene and the sodium salt of p-toluenethiol indicated that this reaction was taking place by the SRNt mechanism. The iodine atom at the bridgehead position para to the nitro group was more readily replaced with p-tolylthio than the iodine atom at the bridgehead position meta to the nitro group. This result is in contrast with that obtained for the dibromo analogue which reacts with sodium p-toluenethiolate to give substitution products with the opposite regiochemical outcome. Further, the rate constants for these reactions are significantly lower than those determined for all other nitrobenzylic compounds.
The reaction of 2—nitro-9,10-diiodo-9,10-ethano-9,10—dihydroanthracene with various carbanions gave only 'reduced' products. In these reactions it was apparent that reduction occurred more readily at a bridgehead position para to a nitro group. Further, the reaction of the diiodide with the sodium salt of 2-(1,1,1-trideuteromethyl) malononitrile showed that reduction occurred by a hydrogen abstraction mechanism, and that the B-hydrogen in the alkyl carbanions was the source of hydrogen(s) in the reaction. Estimates of the rate constants for intramolecular electron transfer from the nitroaromatic group to the bridgehead iodo group in the iodo series of compounds showed that ket (para) was greater than k9, (meta). This result was consistent with the chemical reactivity observed in substitution and reduction reactions involving the diiodo compound.
Irreversible intramolecular electron transfer reactions were also observed in the nitroaromatic compounds with 9-carboxylic acid or 9-nitro substituents.
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Nolan, Melissa A. "Microfabricated iridium arrays : failure mechanisms, investigation of the Hg-Ir interface and their use in Cu or Hg determination /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1999.
Find full textAbstract:
Thesis (Ph.D.)--Tufts University, 1999.Adviser: Samuel P. Kaunaves. Submitted to the Dept. of Chemistry. Includes bibliographical references (leaves 190). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Chahin, Nassif. "Multiplexed detection of SNPs using electrochemical melting curve analysis." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/670966.
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L'objectiu general d'aquesta tesi doctoral és desenvolupar plataformes de geno-sensors de baix cost per a la detecció múltiple de polimorfismes d'un sol nucleòtid. La determinació de polimorfismes d'un sol nucleòtid (SNP) és de gran importància en les ciències de la vida, tenint aplicació en la medicina personalitzada, estratificació de pacients, forense, a més de brindar informació sobre la predisposició a la malaltia. En l'actualitat, els mètodes basats en l'electroquímica es revelen com alternatives atractives a les tècniques més utilitzades per determinar el punt de fusió de l'ADN, per la seva alta sensibilitat, simplicitat, rendibilitat i compatibilitat amb la microfabricació. La primera plataforma es va basar en una reacció d'extensió d'encebadors electroquímics, on els polioximetalats actius redox de Keggin i Dawson es van utilitzar per modificar dideoxinucleótids a través de la formació d'enllaços amida. La segona plataforma es basa en la detecció de polimorfismes d'un sol nucleòtid mitjançant l'anàlisi electroquímic de la corba de desnaturalització. L'enfocament es basa en l'anàlisi de la corba de desnaturalització en fase sòlida que utilitza sondes immobilitzades en elèctrodes d'or. Es va desenvolupar un prototip de dispositiu capaç de detectar un ADN diana que porta un SNP relacionat amb la miocardiopatia amb una sola base en la diferència. Finalment, aquest dispositiu es va aplicar a la detecció de SNP en mostres de sang reals. La diana de seqüència de SNP relacionada amb l'osteoporosi es va extreure d'una punxada al dit i es va amplificar usant PCR asimètrica. A més, es van optimitzar les condicions d'amplificació per obtenir el millor rendiment del producte i es va definir l'SNP d'una mostra de sang.El objetivo general de esta tesis doctoral es desarrollar plataformas de geno-sensores de bajo costo para la detección múltiple de polimorfismos de un solo nucleótido. La determinación de polimorfismos de un solo nucleótido (SNP) es de gran importancia en las ciencias de la vida, teniendo aplicación en la medicina personalizada, estratificación de pacientes, forense, además de brindar información sobre la predisposición a la enfermedad. En la actualidad, los métodos basados en la electroquímica se revelan como alternativas atractivas a las técnicas más utilizadas para determinar el punto de fusión del ADN, debido a su alta sensibilidad, simplicidad, rentabilidad y compatibilidad con la microfabricación. La primera plataforma se basó en una reacción de extensión de cebadores electroquímicos, donde los polioximetalatos activos redox de Keggin y Dawson se utilizaron para modificar didesoxinucleótidos a través de la formación de enlaces amida. La segunda plataforma se basa en la detección de polimorfismos de un solo nucleótido mediante el análisis electroquímico de la curva de desnaturalización. El enfoque se basa en el análisis de la curva de desnaturalización en fase sólida que utiliza sondas inmovilizadas en electrodos de oro. Se desarrolló un prototipo de dispositivo capaz de detectar un ADN diana que porta un SNP relacionado con la miocardiopatía con una sola base en la diferencia. Finalmente, este dispositivo se aplicó a la detección de SNP en muestras de sangre reales. La diana de secuencia de SNP relacionada con la osteoporosis se extrajo de un pinchazo en el dedo y se amplificó usando PCR asimétrica. Además, se optimizaron las condiciones de amplificación para obtener el mejor rendimiento del producto y se definió el SNP de una muestra de sangre.
The overall objective of this PhD thesis is to develop low cost geno-sensor platforms for multiplexed detection of single nucleotide polymorphism. The determination of single nucleotide polymorphisms (SNP) is of great importance in life sciences, having application in personalised medicine, patient stratification, forensics, as well as providing information regarding predisposition to disease. Nowadays electrochemistry-based methods are revealed as attractive alternatives to the most commonly used techniques for determining DNA melting point, because of their high sensitivity, simplicity, cost-effective and compatibility with microfabrication. The first platform was based on an electrochemical primer extension reaction, where the redox active Keggin and Dawson polyoxymetalates were used to modify dideoxynucleotides through amide bond formation. The second platform is based on the detection of single nucleotide polymorphisms using electrochemical melting curve analysis. The approach is based on solid phase melting curve analysis that exploits probes immobilised on gold electrodes. We developed a home-made electrochemical melting curve analysis device, able to detect a DNA target that carries a SNP related to cardiomyopathy from others with only one base in difference. Finally, this device was applied to SNPs detection in real blood samples. Osteoporosis related SNP sequence target was extracted from a finger prick and amplified using asymmetric Recombinase Polymerase Amplification. Also, the amplification conditions were optimised for best product yield, and the SNP from a blood sample was defined.
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Mochizuki, Manabu. "Electrochemical and spectroscopic analysis on the oxidation of catechins." Kyoto University, 2005. http://hdl.handle.net/2433/145449.
Full textAbstract:
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第11239号
農博第1454号
新制||農||902(附属図書館)
学位論文||H17||N3984(農学部図書室)
22848
UT51-2004-U444
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 池田 篤治, 教授 關谷 次郎, 教授 大東 肇
学位規則第4条第1項該当
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El-Shahawi, M. S. E. "Spectroscopic and electrochemical studies of some transition metal complexes." Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381143.
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Treeman, Nicole M. "Electrochemical study of corrosion phenomena in zirconium alloys." Thesis, Cambridge, Massachusetts, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/10945/37785.
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CIVINSShadow corrosion of zirconium alloy fuel cladding in BWR environments, the phenomenon in which accelerated corrosion is experienced when the cladding surface is in close proximity to other metals, has become a potential life-limiting issue for BWR fuel. Recent results from experimentation at MIT, Halden and Studvik suggest that a galvanic coupling drives the phenomenon between the cladding and the adjacent material. However, the actual processes involved are not understood. One key parameter that would help in the understanding of the phenonenon would be a measurement of the actual corrosion current between fuel cladding and adjacent materials in the actual in-reactor environment. The limitations placed on the burn-up of uranium oxide fuel corelates to the amount of corrosion seen through a directly measurable oxide thickness on the waterside of the zirconium alloy cladding. This oxide corrosion product directly correlates to distance from structure components, leading the effect commonly referred to as shadow corrosion. In recent experiments, Studvik determined that there are large ECP differences associated with Inconel and zirconium alloys that correlate to increased galvanic current density when the materials are coupled. In this thesis research, four electrode pairs wre used to measure galvanic cirrent densities in the irradiation environment:Pt-Pt, Zircalloy (Zr-2), Inconel (X-750)-Pt, and Zr-2-X-750. To determine the changes in the coolant water conductivity dus to the presence of radiolysis products, electrochemical potential mesurements of Pt-Pt coupled electrodes were analyzed. Finally, attempts to characterize the observed oxide behavior using measurement from Electrochemical Impedance Spectroscopy (EIS), also known as Alternating Current Impedance, were conducted. Through the measurements taken, analysis of the mechanisms potentially causing the shadow corrosion phenomenon was conducted. The results of the observations included: Measurement of increased conductivity of coolant water correlating to increases in reactor power, measurement of increased galvanic current measurements correlating to increases in reactor power.
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Billing, Caren. "The determination of trace elements in complex matrices by electrochemical techniques." Pretoria : [s.n.], 2000. http://upetd.up.ac.za/thesis/available/etd-03272006-114615/.
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Watson, Charles Martin. "Surface Interactions of Mercury on Gold Foil Electrodes in Electrodeposition and Stripping and ; An Investigation of Free Thiolate Ions from Metal-Thiolate Chalcogenides." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/WatsonCM2003.pdf.
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Lee, Young Mi. "Development of combined scanning electrochemical optical microscopy with shear force feedback using a tuning fork and current feedback." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3037516.
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Hadjichari, Andrew Michael, University of Western Sydney, and School of Civic Engineering and Environment. "Determination of heavy metals on macro- and micro-electrodes by adsorptive cathodic stripping voltammetry and anodic stripping voltammetry." THESIS_XXXX_CEE_Hadjichari_A.xml, 1999. http://handle.uws.edu.au:8081/1959.7/602.
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This thesis describes the application of macro, micro, ultra-microelectrodes and microelectrode arrays to the measurement of trace concentrations of nickel and cobalt in sediment and natural waters by adsorptive cathodic stripping voltammetric methods. In addition the measurement of tin by adsorptive cathodic stripping voltammetry in sediment and natural waters is discussed. Also, the application of macroelectrodes and microelectrode arrays to the measurement of lead, cadmium and zinc in sediment and natural waters by anodic stripping voltammetry is considered. In all cases the determination of the six metals was optimised by investigating the influence of various significant parameters, such as in-situ mercury plating, complexing agent concentration, scan rate, pulse height, accumulation time and potential, buffer concentration and pH. The results obtained for these investigations are discussed in this thesisDoctor of Philosophy (PhD)
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Scott, Timothy Anthony 1963. "Determining the extent of specific adsorption at a solid metal electrode utilizing differential capacitance measurements." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277097.
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The Hurwitz-Parsons method of analysis is employed utilizing a spreadsheet application on an IBM-AT. It is designed to calculate the extent of specific adsorption of an inorganic anion or neutral organic molecule at a solid electrode without knowledge of the point of zero charge. Up to eight bulk adsorbate concentrations represented by differential capacitance versus potential curves may be input. The curves can contain up to 100 points. Output is in units of moles/cm2 and is provided at 10 potentials for each bulk adsorbate concentration. A detailed overview and a formula list of the application are provided. A brief overview of the theories associated with the electrochemical double layer and a related literature review are included.
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Sushko, O. A., and О. М. Bilash. "Use of semiconductor nanomaterials for polycyclic aromatic hydrocarbons detection in water object." Thesis, B. Verkin Institute of Low Temperature Physics and Engineering, NASU, 2013. http://openarchive.nure.ua/handle/document/8874.
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This paper considers a novel method of PAHs in particular BP detection in water solutions with the use of semiconductor nanomaterials. The method constitutes a combination of electrochemical (EC) and electrochemiluminescent (ECL) analysis with the application of nanomaterials (semiconductor QDs) and nanotechnologies for sensor’s electrodes modification.
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Song, Fayi. "Studies on the preparation and electroanalytical applications of chemically modified electrodes." HKBU Institutional Repository, 2000. http://repository.hkbu.edu.hk/etd_ra/268.
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Guymon, Clint. "MPSA effects on copper electrodeposition : understanding molecular behavior at the electrochemical interface /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1112.pdf.
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Payne, Robert R. U. Tatarchuk Bruce J. "Electrochemical characterization and modelling of fuel cells via AC impedance and residence time distribution." Auburn, Ala., 2008. http://hdl.handle.net/10415/1420.
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Khene, Mielie Samson. "Synthesis, photophysics and electrochemical study of tin macrocycles." Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1005041.
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Three non-peripherally substituted tin(IV) macrocylic compounds, octahexylphthalocyaninato dichlorotin(IV) (35a), octahexyltetrabenzo-5,10,15-triazaporphyrinato dichlorotin(IV) (35b) and octadecylphthalocyaninato dichlorotin(IV) (35c) were synthesized and their photophysical and electrochemical behaviour studied. Complex (35b), containing a CH group in place of one of the aza nitrogen atom of the phthalocyanine core, shows a split Q band due to its lower symmetry. The triplet state quantum yields were found to be lower than would be expected on the basis of the heavy atom effect of tin as the central metal for phthalocyanine derivatives (35a and 35c). In contrast, (35b) shows a triplet quantum yield ΦT = 0.78. The triplet state lifetimes were solvent dependent, and were higher in THF than in toluene. Cyclic voltammetry and spectroelectrochemistry of the complexes revealed only ring based redox processes. This thesis also reports on the microwave syntheses of tetrasulphonated tin phthalocyanine and tetrasulphonated tin α,β,γ-tetrabenzcorrole. The latter was only formed at low ratios (< 1:8) of 4-sulfophthalic acid to urea. Both complexes are aggregated in aqueous media, but can be partly or fully disaggregated by the addition of Triton X-100. The SnTSTBC complex has lower triplet life times and yields, while binding constant and quenching (of bovine serum albumin) constant are lower for SnTSTBC, compared to SnTSPc. Finally Non-peripherally (α) tetra- (40) and octa-(38a) substituted dodecyl-mercapto tin(IV) phthalocyanines where synthesized and the electrochemical behavior studied. Cyclic voltammetry and spectroelectrochemistry show ring-based reductions for (38a) and (40); the former shows two ring oxidations, while the latter shows only one ring based oxidation. The adsorption kinetics of (38a) and (40) on a gold electrode have been investigated by electrochemical impedance spectroscopy (EIS). The equilibrium constant (K) for the adsorption and the Gibbs free energy ΔG(ads) of the self-assembled monolayer (SAMs) were evaluated based on the Frumkin isotherm. The interaction factor between adsorbate –adsorbate molecules is also discussed.
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Wong, Wai Cheong. "Electroanalysis of amino acids and dithocarbamates." HKBU Institutional Repository, 1994. http://repository.hkbu.edu.hk/etd_ra/40.
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Mikkelsen, Susan R. "Electroanalysis in highly resistive media." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75776.
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The objective of this research was to design and evaluate an instrumental method for electroanalysis in highly resistive media. A coulostatic detector for high performance liquid chromatography was designed and constructed. Equations were developed to describe the detector's performance under regenerative and nonregenerative experimental conditions. With mobile phases of high resistance, the detector was found to respond to both electroactive and ionic electroinactive species with the magnitude of the observed signal depending on the recent history of the electrode. Thus, the elimination of iR drop by the coulostatic method does not provide a straightforward method for electroanalysis in highly resistive media. At low electrolyte concentrations, double-layer effects become prominent. A method was devised to quantitate the static double-layer effect at solid electrodes.
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Carpenter, Neil Geoffrey. "Electrochemical methods for nitrate, silicate and phosphate analysis in waters." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242534.
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Szpylka, John. "Mass spectral analysis of electrochemical reactants: studies of decarboxylation reactions /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu148775772399743.
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Jiang, Xiong. "Electrochemical studies on the cementation of copper and cobalt with zinc." Thesis, Jiang, Xiong (1987) Electrochemical studies on the cementation of copper and cobalt with zinc. PhD thesis, Murdoch University, 1987. https://researchrepository.murdoch.edu.au/id/eprint/118/.
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The work described in this thesis deals mainly with a fundamental study of two cementation reactions, i.e., Cu(II)/Zn and Co(II)/Zn, using the electrochemical techniques of linear potential sweep voltammetry, cyclic vol tammetry, chronopotentiometry (stripping), capacitance measurements,ring current measurements and impedance spectroscopy. In addition, solution analysis, x-ray diffraction and scanning electron microscopy were employed to achieve a better understanding of the kinetics and mechanisms of the two cementations. The half reactions of the two systems were also investigated as an essential part of the whole study. Of the two systems investigated, the Cu(II)/Zn system, was mainly used as a reference system on which some of the new techniques could be proved.
The Cu(II)/Zn reaction has been shown to be diffusion controlled. Five methods, including solution analysis, have been used to determine the rate of reaction. The values of the rate constants thus determined were in good agreement provided allowance was made for the nonstoichiometry of this reaction due to proton displacement by zinc.
The Co(II)/Zn cementation reaction, though thermodynamically highly favourable, is kinetically very sluggish. Of the factors affecting this reaction, the solution pH was found to play a substantial role. For example, while the reaction is largely under chemical control, at pH 5 the reaction rate becomes limited by the speed at which cobalt(I1) ions diffuse to the reacting metal surface. The favourable influence of a higher pH on the reduction of cobalt(II) carried out either electrochemically or chemically using zinc powder was ascribed to the increasing formation of the electrochemically active species, CoOH+ . Increasing the temperature also favours the shift from chemical control to diffusion control.
Values for the rate constants of the Co(II)/Zn reaction in the absence of added zn2+ ions were determined from Evans' diagram, chronopotentiometry and impedance spectroscopy, The reasons for the differences in the values of rate thus obtained were discussed.
The presence of zinc ions in the reaction solution greatly suppressed the rate of Co(II)/Zn cementation reaction. Several factors have been identified as contributing to the reduced reaction rate. These are the double layer effect, zinc ion and hydrogen atom adsorption, and precipitation of basic zinc salts which blanket the reacting metal surface.
The action of compounds such as Sb(III) and As(III), which are commonly used to activate the Co(II)/Zn reaction in the presence of large amounts of zn2+, was investigated mainly by impedance spectroscopy. From the similarity of the impedance spectra for the reaction i n the presence of benzoqui none, it was inferred that one role of the activators was to suppress the formation of adsorbed hydrogen on the reacting surface and to allow a higher concentration of the active species, COOH'.
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Jiang, Xiong. "Electrochemical studies on the cementation of copper and cobalt with zinc." Murdoch University, 1987. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060816.135721.
Full textAbstract:
The work described i n this thesis deals mainly with a fundamental study of two cementation reactions, i.e., Cu(II)/Zn and Co(II)/Zn, using the electrochemical techniques of linear potential sweep voltammetry, cyclic vol tammetry, chronopotentiometry (stripping), capacitance measurements,ring current measurements and impedance spectroscopy. In addition, solution analysis, x-ray diffraction and scanning electron microscopy were
employed to achieve a better understanding of the kinetics and mechanisms of the two cementations. The half reactions of the two systems were also investigated as an essential part of the whole study. Of the two systems investigated, the Cu(II)/Zn system, was mainly used as a reference system
on which some of the new techniques could be proved.
The Cu(II)/Zn reaction has been shown to be diffusion controlled. Five methods, including solution analysis, have been used to determine the rate of reaction. The values of the rate constants thus determined were in good agreement provided allowance was made for the nonstoichiometry of this reaction due to proton displacement by zinc.
The Co(II)/Zn cementation reaction, though thermodynamically highly
favourable, is kinetically very sluggish. Of the factors affecting this reaction, the solution pH was found to play a substantial role. For example, while the reaction is largely under chemical control, at pH 5 the reaction rate becomes limited by the speed at which cobalt(I1) ions diffuse to the reacting metal surface. The favourable influence of a higher pH on the reduction of cobalt(II) carried out either electrochemically or chemically using zinc powder was ascribed to the increasing formation of the electrochemically active species, CoOH+ . Increasing the temperature also favours the shift from chemical control to diffusion control.
Values for the rate constants of the Co(II)/Zn reaction in the absence of added zn2+ ions were determined from Evans' diagram, chronopotentiometry and impedance spectroscopy, The reasons for the differences in the values of rate thus obtained were discussed.
The presence of zinc ions in the reaction solution greatly suppressed the rate of Co(II)/Zn cementation reaction. Several factors have been identified as contributing to the reduced reaction rate. These are the double layer effect, zinc ion and hydrogen atom adsorption, and precipitation of basic zinc salts which blanket the reacting metal surface.
The action of compounds such as Sb(III) and As(III), which are commonly used to activate the Co(II)/Zn reaction in the presence of large amounts of zn2+, was investigated mainly by impedance spectroscopy. From the similarity of the impedance spectra for the reaction i n the presence of
benzoqui none, it was inferred that one role of the activators was to suppress the formation of adsorbed hydrogen on the reacting surface and to allow a higher concentration of the active species, COOH'.
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Myers, John Nicholas. "An Automated, On-Line Electrochemical Chlorite Ion Sensor." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1313594430.
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Lau, Chi Hian. "Chemical, electronic and electrochemical properties of diamond thin films." Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:53a0886c-14ad-431a-975d-0ecca8fc8968.
Full textAbstract:
Diamond is of interest as an advanced functional material, since the extreme physical properties of diamond, suggests it is ideally suited to a range of new demanding applications. In this context, the thesis explores basic surface chemical properties of diamond thin films, along with electrochemical, electronic and electron emission processes involving this material. New experiments are reported concerning the nature of surface conductivity on diamond. Measurements clearly show that the conductivity only arises if a hydrogenated diamond surface is exposed to water vapour, in the presence of chemical species capable of acting as electron acceptors. The conduction properties of surface conductive diamond in aqueous solution are also studied, and the first detailed electrochemical investigations of this material are described. Comparative electrochemical studies of nanocrystalline and boron-doped diamond have been performed. Investigations of electrode stability, and the accessible "potential window" are described, as well as the behaviour of a range of 'redox' systems, including transition metal complexes, metal deposition/stripping, and bio-related organic species. Significant differences between the behaviour of nanodiamond and microcrystalline boron-doped material are observed. A range of surface chemical and threshold photoemission studies of diamond thin films are reported. The results indicate that quantum photoyields (QPYs) are insensitive to the diamond "quality", although the wavelength selectivity is dependent on it. The adsorption of oxygen strongly reduces the QPY, although this only occurs slowly in the presence of O2 because of a low reactive sticking probability. Much more rapid uptake of oxygen and consequent reduction of photoyield is observed in the presence of atomic O or electronically excited dioxygen O2*. The presence of alkali metals on the diamond surface increases the QPY, and reduces the sensitivity of the QPY to surface oxygen. Significant differences between the surface chemical properties of Li, and other adsorbed akali metals (K and Cs) are observed.
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Thomas, Michael B. "Application of a swept-potential electrochemical detector to the HPLC analysis of nitrosamines and carbamate pesticides." Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/26978.
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Kariuki, Nancy N. "Nanostructured materials for electroanalytical applications." Diss., Online access via UMI:, 2005.
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