ELECTROCHEMICAL ANALYSIS

Author: ESPUELAS INDIA FRANCISCO JAVIER.
Year: 2003.
University: ZARAGOZA [www.unizar.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: The thesis work have developed different procedures for tying up bioreactivos on the surface of the electrode for determining cholesterol. In the first part of the report describes the study of a biosensor amperométricos enzyme immobilization constructed by using entrampamiento physical in the interior of a matrix polymer polipirrol. An important innovation introduced was the introduction of an additional layer of polymer polinaftaleno built from monomers 1.5 -Diaminonaftaleno. This new configuration is optimized obtained biosensors with good analytical properties of permeability and character driver of biosensor. In a second phase, we studied the improvement in the transduction of hydrogen peroxide generated in the enzymatic reaction between the enzyme cholesterol oxidase and analyte cholesterol by co-inmovilización in the structure of a catalyst electrochemical biosensor blue prusia. There was an increased flow detected in the selective reduction of hydrogen peroxide to a potential work cathodic which allowed the easing of interference. It introduced a novel procedure that immobilization was the addition of a single autoensamblada on electrode (mercaptano) achieving an increase in life span in the biosensor as a result of the increase in adhesion of the layer of blue prusia. In the third part of the thesis was improved the effectiveness of cholesterol biosensor using a novel procedure for rebuilding apo-enzima (apo-COx) optimized (reconstitution spot) on the surface of the electrode. We performed the separation of the active enzyme FAD its apo-proteína to implement the reconstitution of the same on a single FAD immobilized on the electrode. This procedure allowed the link of each enzyme molecule with its mediator charge transfer, which improved both the sensitivity of the biosensor, and in particular its effectiveness, as well as the lifetime of the same. Finally, we developed a biosensor for the determination of cholesterol without immobilization of enzyme COx, using a molecular modeling analyte cholesterol on the structure of a monolayer autoensamblada on the electrode, and studied their possible transduction voltamétrica. This biosensor showed increased sensitivity, biosensors with respect to the previously studied enzyme, as well as less time in the same building. We should also mention the detection limit reached with the same due to the small number of holes modeled on the structure.

Author: MOREDA MORO JOSE M..
Year: 2004.
University: PAÍS VASCO [www.ehu.es].
Place of defense: FACULTAD DE FARMACIA DE VITORIA.
Place of preparation: FACULTAD DE FARMACIA.

Summary: It is studying the properties electroanalíticas, nature's balance and electrochemical processes that give rise to the processes red-ox both acids. Used to this cell EFTA of Metrohm Hg electrode with the cell and conventional. The various options are considered for the quantitative determination of both, based on different peaks reduction, which appear in the spectrum of electrochemical its first sweep cyclical and later sacándose conclusions about the usefulness of the proposed methods, both in the conventional as cell in the cell EFTA.

Author: PRIETO SIMÓN BEATRIZ.
Year: 2004.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: ESCUELA DE POSTGRADO.

Author: PALENZUELA HENS BEATRIZ CRISTINA.
Year: 2004.
University: CÓRDOBA [www.uco.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: The dissertation submitted has contributed to the development of new analytical methodologies to increase the level of automatizacióny simplíficación of procesosde measure both chemical and microbiological. This has been developed: A. Methodologies used in extraction systems with supercritical fluids through an alternative system of trap liquid, which has enabled one hand studies of biological activity of the extracts of polyphenols and other realízar a link online these extraction systems to detect amperométrica . From the results it is proposed a new use of pomace uvacomo source extraction polífenoles, dándoleasí a new use for this industrial waste. B. Methodologies that incorporate detection piezoeléctrica. Tapping into the piezoelectric crystal is an electrode coating of gold, has developed a method HPLC-detección piezoeléctrica for monitoring inorganic mercury and methylmercury in natural waters. This system has achieved a high selectivity and sensitivity comparable with instrumental techniques more complex and sophisticated. It has also developed a new piezoelectric sensor amalgamated with mercury to flow systems, which provides a high sensitivity and selectivity for sulfur compounds. With this sensor has proposed an automated method for detecting S02 in wine samples. The proposed method is cheaper and provides better results than the commonly used method for this analyzes. It also allows the analysis both in white wines such as reds. C. Methodologies for análísis microbiology. It has proposed a system of screening simple, fast and inexpensive for determination of bacteria in food by amperometría. For confirmation has developed a method for the identification and quantification of eight types of bacteria by Capillary Electrophoresis by changing its surface so getting the effective separation of eight different types of bacteria in one sample. This system has been applied to the microbiological analysis of alímentos.

Author: Gutés Regidor Albert.
Year: 2005.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: Universidad Autonoma de Barcelona.
Place of preparation: Universidad Autonoma de Barcelona.

Summary: There is growing interest in chemical analysis because of the social need of information in many areas. Industrial process controls, environmental monitoring, as well as product quality monitoring, are some of the points where research is immersed nowadays. One of the research lines that is getting more significance in Analytical Chemistry is the development of automatic systems of analysis because of this increasing need of information, sometimes in real time. It is already possible to determine a huge variety of analytes in a single analysis when using heavy laboratory set-ups such as gas chromatography or mass spectrometry, but their cost and maintenance is sometimes a drawback in laboratory implementation. The need of robust and cost-effective devices has pushed researchers into the development of simple systems that do not try to compete with heavy laboratory set-ups, but that are good enough to satisfy the need of information in many situations. In this effort of developing new analytical systems it is possible to find those systems coined under the name of electronic noses and electronic tongues. These devices are considered as biomimetic systems, as long as they are based in imitating the human senses of smell and taste. The first electronic noses appeared many years ago, but are still useful in many areas. Electronic tongues appeared some years after the electronic noses, and are still considered as one of the research topics in Analytical Chemistry. The development of these systems has been a compendium of efforts in many laboratories of many countries around the world. The present work pretends to add some useful information into the electronic tongues development, with the aim of increasing the significance of electronic tongues in the present research. The development of an automated sequential injection system has been one of the key points in our work, as long as it is known that electronic tongues need huge amount of previous knowledge of the analytical problem. By automation of the system it is possible to obtain flexibility in measurements, and thus it is possible to use the same manifold for different applications. Because of the novelty of electronic tongue development in our laboratories, we started with simple analytical problems with the scope of increasing the complexity of the determinations. It is because of this fact that it is possible to see a defined path in the present work being complexity of the analytical problem and/or the use of more sophisticated analytical devices the conducting beam. Five different electronic tongues are presented in this work, each of them with different analytes and measuring devices. The previous knowledge of our research group in the sensor field has permitted the use of several sensors. Development of different measuring cells, in accordance with the kind of sensors used is another accomplished target in the present work. It has to be mentioned that one of the five electronic tongues has been possible due to a visit at the IFM laboratories in Linköping University, Sweden. The previous knowledge of this research group in the electronic tongue field permitted the accomplishment and development of another application of the electronic tongues. Finally, it also has to be mentioned that the presented work has been presented in several international conferences, and that has permitted the publication of different papers attached at the end of this report.

Author: Massana Aiguadé Maria.
Year: 2005.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: Facultad de Ciencias, Edificio Cn..
Place of preparation: Facultad de Ciencias..

Summary: The introduction of a more restrictive regulatory environment generates demand for effective information and intensive offering those responsible the appropriate tools to optimize the management and administration of resources (control, surveillance, prevention, warning). Related to the management of waste treatment plants require wastewater control systems to improve the effectiveness of bioprocesses. In this context, the enormous complexity of the sample more difficult the task of extracting information to optimize the effectiveness of the process and reduce the cost. The growing demand for information on new parameters for better characterization of the process, is driving the development of a new generation of sensors more selective and reliable as well as on-line analyzers chemical parameters of new techniques based on continuous flow in autonomous operation . To achieve these objectives, the tools must be simple, robust and dedicated. In this case, the loss of versatility has to be compensated by increased reliability of the results obtained over time monitoring. The devices measure must provide a suitable selectivity, fast response time and long periods operating without supervision. The monitoring of these processes is commonly physical sensors and a small number of chemical sensors. But its use causes significant problems in-line operation and maintenance when samples are very dirty or aggressive. The design process analyzers based methodologies for continuous flow and electrochemical sensor (potentiometric) detectors enable solve many of the existing problems. These teams conjugarían the benefits of simplifying the analytical procedure provided by potentiometric sensors with simplification, in terms of automation, sample pretreatment and autonomous operation providing methodologies for continuous flow. The argument presented is framed in different development projects and technology transfer, and establishes the foundations of applicability of chemical potentiometric sensors in terms of reliability of the information obtained and robustness over long periods of monitoring. The results presented here have allowed the control and optimization of a process manufacturing cloroderivados acid isocianúrico developing a system that incorporates a flow ESI (ion selective electrode) tubular membrane mobile carrier loaded with selective ion monohidrógenoisocianurato. Moreover, it has developed an automated analyzer nitrate based on the technique of continuous flow FIA and a sensor sensitive to nitrate ion for the determination of this parameter in the process of nitrification in wastewater treatment. For the same application, has developed an analyzer for monitoring nitrite based on a colorimetric detection at 540 nm from a compound azo. The automation of the process is carried out with the FIA technical stage that integrates a gaseous diffusion to eliminate the problems arising from the direct optical measurement and increase the selectivity of the method. Finally, it has developed a system to analyze sewage sludge for the indirect determination of hydrogen sulfide. This system integrates a cell pervaporación as a system of separation of the analyte ion in the form of sulfur and determined by a continuous ion selective electrode sulfur.

Author: DE LA ESCOSURA MUÑIZ ALFREDO.
Year: 2005.
University: OVIEDO [www.uniovi.es].
Place of defense: FACULTAD DE QUIMICA.
Place of preparation: FACULTAD DE QUIMICA UNIVERSIDAD DE OVIEDO.

Summary: In this Doctoral Thesis is used for the first time, aurotiomalato sodium, a complex of gold (I), as a mark electroquímca of biomolecules. This complex of gold is used as a treatment for rheumatoid arthritis and is carried by the bloodstream united basically albumin. This union between albumin and aurotiomalato sodium passes through the thiol group of cysteine 34 of albumin and the gold atom in the compound. This interaction is used to mark molecules such as human serum albumin and immunoglobulin G rabbit in order to use these molecules marked for the development of inmunosensores on carbon electrodes vitrified. The detection of complex gold coupled with the protein or antibody is carried out utilizing their catalytic effect on the silver electroplating. The inmunosensores developed are tested on biological matrices such as serum or synthetic urine. In the latter part of this Doctoral Thesis was also marked strands of DNA that are used to build genosensores for detecting SARS virus on carbon electrodes vitrified and electrodes serigrafiados carbon. In the latter case to detect the complex together with the gold thread of DNA using the catalytic properties of this compound on the reduction of protons environment.

Author: DIAZ GONZALEZ MARIA.
Year: 2005.
University: OVIEDO [www.uniovi.es].
Place of defense: FACULTAD DE QUIMICA.
Place of preparation: FACULTAD DE QUIMICA UNIVERSIDAD DE OVIEDO.

Summary: In this Doctoral Thesis develop different inmunosensores electoquimicoas where it is used as a trademark alkaline phosphatase enzyme and 3-indoxil phosphate as a substrate. These inmunosensores are built using electrodes serigrafiados carbon as transducers of the analytical signal.

Author: GISMERA GARCÍA MARÍA JESÚS.
Year: 2005.
University: AUTÓNOMA DE MADRID [www.uam.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: Among the metallic elements considered as pollutants are lead, copper and mercury, heavy metals presenting high toxicity and in some cases are found in large amounts in the environment. The importance of controlling the levels of these contaminants in natural waters, drinking water, sediments and industrial waste has generated a lot of interest in the development of new analytical methodologies for its determination. The potentiometric sensors represent a very interesting area and expanding within the Analytical Chemistry. His great development and acceptance is due to the possibility of direct action or act as electrodes indicators valuations, regardless of color or turbidity of the sample, without affecting the dissolution of analysis, and the fact that such determinations require relatively inexpensive equipment and notebooks. They are very simple devices with features that have found applications in many fields. The electrodes modified carbon paste are a group of chemical sensors with electrochemical responses very stable. They produced the intentional alteration of the surface with a specific reagent for improvements in the screening of analyte. Despite excellent analytical advantages, for the moment, there are relatively few applications of carbon paste electrode as potentiometric sensors. The purpose of the Doctoral Thesis is the development of potentiometric sensors for the determination of metals considered priority pollutants such as copper, lead and mercury. This will build the new sensors modified carbon paste containing organic ligands in its composition groups guy and ditio. It optimizes its construction and characterized its basic analytical parameters. The new sensors developed presented optimal analytical parameters, as quick responses, low detection limits and answers appropriately selective. Once characterized sensors and the process taking place in their area, are used for identifying, directly or through potentiometric valuation of the metals in samples of a different nature. Furthermore, because of the increased importance interaction studies with natural organic matter, such as toxicity and increasing presence of these metals in water and soil, the new sensors are used to study the interaction between metals húmicas and substances. Finally, and following the latest trends in the field of sensors are used in the analysis of mixtures of metals in the same sample.

Author: BRAVO FLORES DAVID.
Year: 2005.
University: PAÍS VASCO [www.ehu.es].
Place of defense: FACULTAD DE FARMACIA DE VITORIA.
Place of preparation: UPV/EHU.

Summary: We have determined blockers alfa-adrenérgicos alfuzosín, doxazosín, prazosín and terazosín by various analytical techniques both in static and in dynamic regime. Alfuzosín and terazosín were determined by differential pulse voltammetry and square wave, UV spectrophotometry, espectrofluorimetría and fluroimetría-FIA. The four analytes have been determined by HPKLC detection fluorimétrica and by capillary zone electrophoresis with UV-VIS detection by network photodiodes. We have determined the constants of acidity polarográfica and espectrofotométricamente to alfuzosín and trazosín. Have also been studied its process of reducing mercury electrode with proposing a mechanism for the process of reducing them. In all techniques are optimized conditions of measurement. All have subsequently been validated methods, as recommended by the IUPAC. Finally, we have applied analytical methods developed for the determination of the four analytes in real samples, both in commercial drugs, as in urine.

Author: PERLO MARTINEZ PATRICIA ANALIA.
Year: 2005.
University: VIGO [www.uvigo.es].
Place of defense: FACULTAD DE QUÍMICA.
Place of preparation: E.U.I. TÉCNICA INDUSTRIAL, UNIVERSIDAD DE VIGO.

Summary: The continuing stability of the complexes formed between metallic cations and chemical species with high power binder are important parameters to know the chemical that are both. In the particular case of complexes formed in a position 'environmental' (complexes that exist in natural ecosystems), or learn to calculate these parameters of interaction is, if anything, even more important, because together with the speed of the processes involved, govern the conduct in the media, which directly affects the quality of life of people who live in them, including humans. It is not surprising, therefore, that research on the complexation abound in the literature. In fact there are so many involved different cations with ligands as diverse, as changing conditions, and performed with such varied instrumental techniques which would require virtually an encyclopedia just to collect the parameters of complexation. Not for nothing is one of the subjects where the number of publications has been the highest in recent years. However, as far as has been possible to trace in the literature, all determinations suffer from a 'default' essential, namely, all using a single curve or a set of experimental data, experimental, from which and through a complex treatment, in many cases almost alchemical, there is a numeric value that represents or is related to the chemical or electrical interactions that exist in the fears studied, almost always expressed as a constant stability. There is no doubt that these values are important and meaningful, but its usefulness from a statistical point of view is reduced. The existence of ever more powerful computers that can be dealt with makes these sets of experimental data sets as if they were older, which makes it possible to extract much more information, and specifically enhance the fidelity and the very usefulness of the results. Among the statistical methods that can utilizares pair of this role, perhaps one of the most useful (not the most) (employees, is the bobtstrapping developed by Bradley Efron in 1977. Essence of the method is to treat the whole subsets total data as if they were the only ones that exist, and from the same obtain the desired information. (In the case presented in this report, there will be an array of experimental points from which are extracted N vectors points with m , where n is greater m). This information appears as a distribution of results both larger the higher N, instead of a single value obtained from the original data. distribution obtained provides greater alignment with the 'true value' interested parameter calculation, and also allows perform statistical treatments that are not possible in the original distribution due to its small size.'s election system is justified by the extensive use of eucalyptus in the process of reforestation carried out in Galicia in recent years, and the importance of them in generating humic extracts and humus-like. These, in addition to being the organic constituents of all natural systems, have an overriding importance in the processes of soil pollution by heavy metal complexation . Moreover, the statistical method (Bootstraping), now applies to the most diverse range of situations, with results that postulated as a very interesting tool in complex systems as is our case, since the substances húmicas and hummus-like they do not have a definite chemical formula if they are mixtures of 8 substance 3dd as structurally similar. implementation of the method requires among other things the development of simple routines, written in FORTRAN, to carry out the method. Bearing in mind this objective, in this memory has been the analysis of experimental data obtained by the rating conductimétrica extract humus-like with strong base at different temperatures and in the presence of complexing ions (Cu (II)) using this routines developed computer, and making below considerations statistics.

Author: SERRANO PLANA NÚRIA.
Year: 2006.
University: BARCELONA [www.ub.es].
Place of defense: FACULTAD DE QUÍMICA.
Place of preparation: FACULTAD DE QUÍMICA.

Summary: The main aim of the thesis has been to deepen the study of heavy metal complexation with ligands that are different kinds of complexes (simple and macromolecular labile and inert) techniques voltamperométricas and cronopotenciométricas of redisolución. First, they have compared the benefits of redisolución anódica voltammetry (ASV) and the cronopotenciometría of redisolución (SCP) in the study of complexation of metal systems with ligands growing complexity and systems multi-metal, with the whether the purpose of SCP is a reasonable alternative to the ASV in the field of heavy metal speciation. Secondly, it has participated in the development of a methodology for analyzing the curves obtained by cronopotenciometría of redisolución by scanning (SSCP). This methodology is intended to facilitate the calculation of parameters of complexation in the case of valuations SSCP with a limited number of relationships metal-ligando Finally, the study of complexation with peptides with a high content of thiol groups. The strong adsorption of these and especially the irreversibility of the signs of reducing metallic complexes with the peptide require, the implementation of cronopotenciometría of redisolución with accumulation by adsorption to constant intensity (AdSCP).

Author: PARRA GODAYOL ALEIX.
Year: 2006.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: UNIVERSIDAD AUTÓNOMA DE BARCELONA.

Summary: Pervasive computing is a novel concept which main goal consists in monitoring anything anywhere. This is a useful tool to eregistrate key parameters for the study of agricultural processes such as concentrations of gases and nutrients, temperature and humidity. The in situ values are processed by means of a wireless net and both qualitative and quantitative data are obtained with space and time resolution. The first step to achieve such automation is the development of reliable, robust and low cost sensors to be integrated in these nets. These sensors will provide representative data without human interaction in samples matrixes. This thesis includes development and technology transfer projects focused on evaluating the applicability of potentiometric chemical sensors to long monitoring periods. For this purpose, reliability and robustness of the obtained information have been studied. This work aims to be a starting point of one of the first pervasive computing systems and to validate ion-selective electrodes for their use in a complex matrix. In this sense, this work has been focused to the determination of fertilizer ions, mainly phosphate, in soils by means of selective electrodes. This work is divided in three main parts. First, a new host for an ortho-phosphate sensor is studied theoretically and experimentally. This host shows sensitivity and selectivity for the analite (H2PO4-, HPO42-). Computational studies lead to a recurrent circle of optimisation of the studied hosts and their applicability in ion-selective electrodes is determined by means of potentiometric studies. A flow injection analysis method is also developed to determine the concentration of inorganic and organic 8 phospho 4f5 rous (the later in the phytate form) in food samples. The second part or the work comprises development of the necessary technology for direct monitoring of ions (pH, phosphate and calcium) in soils. That leads to a first sensor system prototype which includes humidity and temperature sensors which allow the correlationship of these two variables with ionic concentration. Finally, a second prototype includes, in addition, nitrogen (NH4+, NO3-), potassium and phosphorous (HPO42) sensors. This prototype provides data monitoring the NPK group and its correlation with humidity and temperature at three different deep levels: 5, 20 and 50 cm.

Author: GÓMEZ GONZÁLEZ MARÍA JESÚS.
Year: 2006.
University: BURGOS [www.ubu.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: Heavy metals are recognized as highly toxic and hazardous pollutants, only pesticides outweigh the danger and toxicity. The main feature that distinguishes heavy metals and other contaminants defines its high risk factor, is that they are not biodegradable. These metals include gallium, whose presence in natural environments is increasing as a result of its increasingly industrial use. In this work we have developed fast and sensitive electrochemical methods for the determination of the level of trace metals. These methods are based on the formation of complex organic likely to be adsorbed on a drop of mercury electrode. Complejantes as the pirrolidinditiocarbamato ammonium (APDC), the violet pirocatecol (PCV) and diethyldithiocarbamate (DDTC) has been shown to have greater utility in the electrochemical analysis of this element. Another element analysis which is of interest is antimony. The toxicity of this element is heavily dependent on its chemical form and its oxidation state, with the antimony compounds (III) much more toxic compounds pentavalent antimony. Therefore, in the case of antimony, is very useful development of an analytical procedure, which not only allows the quantification of that element but also the speciation of the two states of oxidation in a given sample. This paper describes different methods to perform the speciation of antimony. These methods are based on the ultraviolet spectrophotometry and differential pulse voltammetry of redisolución adsorptive with complexing as pirogalol and red pirogalol using multivariate calibration methods (PLS). There is now a growing interest in the development of miniature electrodes for use in electrochemical instruments. Such electrodes adds new benefits to those already known electrochemical methods. For this reason, one of the main objectives of this work has been manufacturing electrodes serigrafiados disposable through technology "screen-printing", which have proved very useful in the analysis of gallium and antimony-level traces in various matrices.

Author: MORENO CODINACHS LIA.
Year: 2006.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: INSTITUTO DE MICROELECTRONICA DE BARCELONA.
Place of preparation: UNIVERSIDAD AUTONOMA DE BARCELONA.

Summary: It has been designed and constructed a multi based on a set of six sensors ISFET, an IDS sensor and a silicon diode integrated monolíticamente and manufactured using wafer BESOI. We have placed two types of membranes based on polymers fotocurables and glass calcogenuros in sensors ISFET. In his deposition, has developed a novel technology. The devices have been characterized both as electrochemical power. The device has been applied developed a measuring system IAF, as the language in various electronic samples of beverages. Have been distinguished and classified different samples of mineral water business, musts and wines from different grape varieties and different vintages. There have also been quantified certain parameters of these samples.