La Calidad vista por los estudiantes: Participación de los estudiantes de la UBU en los Sistemas de Garantía de Calidad

Ponencia presentada en: Encuentro sobre la calidad en los sistemas de información, Burgos, 9-10 de julio de 200

Direct determination of ascorbic acid in a grapefruit: paving the way for in vivo spectroelectrochemistry

The study of real samples is more complicated than the study of other systems. However, the inherent advantages of UV–vis absorption spectroelectrochemistry should overcome some difficulties related to direct measurements in complex matrices. For this reason, a singular spectroelectrochemistry device has been fabricated and validated. The novel cell is based on single-walled carbon nanotubes, which are filtered and subsequently press-transferred on a polyethylene terephthalate support using a stencil with a custom design. With this new methodology, working, counter, and reference electrodes are completely flat on the surface, where two optical fibers are fixed in a long optical path length configuration. To demonstrate the usefulness of this device and the power of spectroelectrochemistry techniques to solve problems of the current world, this device is used to quantitatively detect the concentration of ascorbic acid in a complex matrix such as a fruit, directly, without any previous sample pretreatment. The ease to fabricate the device, the advantages related to its use, and the excellent results obtained not only with univariate but also with multivariate analysis, shed more light on the analysis of samples as they occur in nature. According to the particular features of this cell, to the best of our knowledge this is the first spectroelectrochemical sensor that can be inserted directly in a biological matrix, laying the groundwork to perform in vivo measurements in a near future.Ministerio de Economıá y Competitividad (CTQ2014-55583-R, CTQ2014-61914-EXP, CTQ2015- 71955-REDT) and Junta de Castilla y León (BU033-U16

Application of spectroelectroanalysis for the quantitative determination of mixtures of compounds with highly overlapping signals

The amount of qualitative and quantitative information provided by a UV–vis absorption spectroelectrochemistry (SEC) experiment is sometimes wasted. However, almost all electrochemical and spectroscopic data can provide valuable information. In this spirit, the main objective proposed in this work is the quantitative resolution of catechol/dopamine (CAT/DA) and dopamine/epinephrine (DA/EP) mixtures, using spectroelectrochemical sensors in long optical path length arrangement based on bare optical fibers in parallel configuration with respect to carbon nanotubes or screen-printed electrodes. These compounds show extremely similar electrochemical and spectroscopic responses at high acidic pH, being impossible to determine their concentrations in the mixtures just using univariate regression models. To our knowledge, the SEC ability to resolve complex mixtures has never been demonstrated before with signals with this degree of overlapping. The quantitative analysis of these mixtures is possible using multivariate regression analysis of a set of time-resolved spectroelectrochemical data with a powerful statistical tool such as parallel factor analysis (PARAFAC). PARAFAC enables us to extract all the information from the experiments, allowing us to quantify the different analytes in mixtures of varying concentrations with excellent results. This milestone for spectroelectroanalysis illustrates the expected capabilities of SEC and demonstrates experimentally the potential of this technique for sensing of biomolecules.Ministerio de Economía y Competitividad (CTQ2014-55583-R; CTQ2014-61914-EXP; CTQ2015-71955-REDT; CTQ2017-83935-R AEI/FEDER, UE) and Junta de Castilla y León (BU033-U16) is gratefully acknowledged. Jesus Garoz- Ruiz thanks Ministerio de Educación, Cultura y Deporte for his FPU fellowship (FPU12/02795) and Ministerio de Economía y Competitividad for his postdoctoral contracts (CTQ2014-55583-R; CTQ2017-83935-R AEI/FEDER, UE)

Simplifying the assessment of parameters of electron-transfer reactions by using easy-to-use thin-layer spectroelectrochemistry devices

UV–Vis absorption thin-layer spectroelectrochemistry greatly contributes to the assessment of parameters of electron-transfer reactions by providing electrochemical and spectroscopic information obtained simultaneously in a confined space around the working electrode. In this work we present an ingenious modification of a spectroelectrochemistry device based on carbon nanotubes and bare optical fibers to perform UV–Vis absorption thin-layer spectroelectrochemistry measurements. The working and counter electrodes are made of carbon nanotubes filtered and press-transferred onto a flat support where a painted silver line acts as pseudo-reference electrode. To perform high sensitivity measurements, two bare optical fibers are fixed to the support in a parallel arrangement. In a novel development, a quartz plate is placed on top of the bare optical fibers in order to create a thin layer whose thickness is reproducibly controlled by the diameter of the optical fibers. This methodology is also successfully applied using commercial screen-printed electrodes. Three different electroactive compounds, ferrocenemethanol, o-tolidine and [Ru(bpy)3]2 +, are studied and good results are obtained. As demonstrated below, these long optical path UV–Vis absorption thin-layer spectroelectrochemistry cells considerably reduce the complexity associated with this type of devices, eliminating one of the major disadvantages of this technique and making it much more accessible to the scientific community.Ministerio de Economía y Competitividad (CTQ2014-55583-R, CTQ2014-61914-EXP, CTQ2015-71955-REDT) and Junta de Castilla y León (BU033-U16)Ministerio de Economía y Competitividad (CTQ2014-55583-R, CTQ2014-61914-EXP, CTQ2015-71955-REDT) and Junta de Castilla y León (BU033-U16

Spectroelectrochemical Determination of Isoprenaline in a Pharmaceutical Sample

UV/Vis absorption spectroelectrochemistry (SEC) is a multi-response technique that has been commonly used for the characterization of materials and the study of reaction mechanisms. However, it has been scarcely used for quantitative purposes. SEC allows us to obtain two analytical signals simultaneously, yielding a dual sensor in just one experiment. In the last years, our group has developed new devices useful for analysis. In this work, a SEC device in parallel configuration, based on optical fibers fixed on screen-printed electrodes, was used to determine isoprenaline in a commercial drug, using both, the electrochemical and the spectroscopic signals. In this commercial drug, isoprenaline is accompanied in solution by other compounds. Among them is sodium metabisulfite, an antioxidant that strongly interferes in the isoprenaline determination. A simple pretreatment of the drug sample by bubbling wet-air allows us to avoid the interference of metabisulfite. Here, we demonstrate again the capabilities of UV/Vis absorption SEC as double sensor for analysis and we propose a simple pretreatment to remove interfering compounds.Ministerio de Economía y Competitividad (Grant CTQ2017-83935-R-AEI/FEDERUE), Junta de Castilla y León (Grant BU297P18), and Ministerio de Ciencia, Innovación y Universidades (Grant RED2018-102412-T). F.O. is grateful for the contract funded by Junta de Castilla y León, the European Social Fund and the Youth Employment Initiative. J.G.R. thanks Ministerio de Economía y Competitividad for his postdoctoral contract (Grant CTQ2017-83935-R AEI/FEDER, UE)

Normal or parallel configuration in spectroelectrochemistry? Bidimensional spectroelectroanalysis in presence of an antioxidant compound

This work demonstrates how the way a chemical system is sampled plays a key role in spectroelectroanalysis, illustrated by the quantification of an analyte in presence of an antioxidant compound. For this purpose, bidimensional spectroelectrochemistry experiments were performed using epinephrine as the model analyte and ascorbic acid as antioxidant and interfering compound, as a proof of concept. This is the first time that three calibration curves are obtained simultaneously on a single spectroelectrochemistry data set, one for the electrochemical signal and two for the optical responses in normal and parallel configurations. The differences between the two optical arrangements, that are related to the diffusion process which is an essential feature for the spectroelectrochemical detection of compounds, have been experimentally demonstrated. As can be observed, the spectral signal in parallel configuration allows us to obtain the best analytical results, since in this configuration only the first micrometers of the solution adjacent to the electrode surface are sampled, thus removing the interfering effect of the antioxidant compound. This fact does not occur with either the electrochemical signal or the spectral response in normal configuration. Furthermore, it has been shown that the parallel configuration provides better results than the normal configuration in terms of sensitivity. In summary, epinephrine is successfully detected in a simple and effective way, even in the presence of a direct antioxidant compound such as ascorbic acid at different concentrations levels, which makes spectroelectrochemistry a good choice for quantitative analysis.Authors acknowledge the financial support given by Ministerio de Ciencia e Innovación and Agencia Estatal de Investigación (MCIN/AEI/ 10.13039/501100011033, PID2020-113154RB-C21) and Ministerio de Ciencia, Innovación y Universidades (Grant RED2018-102412-T). Fabiola Olmo is grateful for the contract funded by Junta de Castilla y León, the European Social Fund, and the Youth Employment Initiative

Optically transparent electrodes for spectroelectrochemistry fabricated with graphene nanoplatelets and single-walled carbon nanotubes

Ministerio de Econom ´ıa y Competitividad (CTQ2014-55583-R, CTQ2014-61914-EXP

Spectroelectrochemistry of Quantum Dots

Spectroelectrochemistry (SEC) is a set of techniques with many advantages in the study and characterization of materials. Although SEC has not yet been widely used to study quantum dots (QDs), the information extracted from SEC experiments about these nanostructures is very useful. Most of the works that use SEC to study QDs are high-quality pieces of research. This review intends to show how to perform SEC in an easy way and what information can be obtained using these techniques. Most of the examples shown in this review are related to semiconductor and carbon QDs. After a brief introduction, some optoelectronic properties of QDs and the main SEC techniques are described. The capabilities of SEC for the study of QDs are illustrated with examples extracted from literature. Finally, the needs of SEC to become a user-friendly technique and its evolution to become more powerful are commented in the last section of the review.Ministerio de Economía y Competitividad (Grants CTQ2017-83935-R-AEI/FEDERUE) and Junta de Castilla y León (Grant BU033-U16 and BU297P18). J.G-R. thanks UBU for his postdoctoral contract. J.V.P-R. thanks JCyL for his postdoctoral fellowship (Grant BU033-U16). Thanks to J

A Flexible Platform of Electrochemically Functionalized Carbon Nanotubes for NADH Sensors

A flexible electrode system entirely constituted by single-walled carbon nanotubes (SWCNTs) has been proposed as the sensor platform for -nicotinamide adenine dinucleotide (NADH) detection. The performance of the device, in terms of potential at which the electrochemical process takes place, significantly improves by electrochemical functionalization of the carbon-based material with a molecule possessing an o-hydroquinone residue, namely caffeic acid. Both the processes of SWCNT functionalization and NADH detection have been studied by combining electrochemical and spectroelectrochemical experiments, in order to achieve direct evidence of the electrode modification by the organic residues and to study the electrocatalytic activity of the resulting material in respect to functional groups present at the electrode/solution interface. Electrochemical measurements performed at the fixed potential of +0.30 V let us envision the possible use of the device as an amperometric sensor for NADH detection. Spectroelectrochemistry also demonstrates the effectiveness of the device in acting as a voltabsorptometric sensor for the detection of this same analyte by exploiting this different transduction mechanism, potentially less prone to the possible presence of interfering species.FEDER and both the Spanish Ministerio de Economía y Competitividad (Grants CTQ2017-83935-R-AEI/FEDER-UE) and the Consejería de Educación -Junta de Castilla y León- (Grant BU297P18). Jesus Garoz-Ruiz thanks Ministerio de Economía y Competitividad for his postdoctoral contracts (CTQ2014-55583-R; CTQ2017-83935-R AEI/FEDER-UE). Fabio Vulcano thanks the ISOF institute of CNR for supporting his PhD Grant. Nicola Porcelli thanks Università di Modena e Reggio Emilia for supporting his stay at the University of Burgos

Multipurpose spectroelectrochemistry: paving the way for in vivo measurements

“Multipurpose Spectroelectrochemistry: Paving the Way for In Vivo Measurements” es el título de la tesis doctoral realizada por Jesús Garoz Ruiz bajo la dirección de los doctores Aránzazu Heras y Álvaro Colina. Este trabajo realizado en la Universidad de Burgos resuelve con óptimos resultados tres grandes retos dirigidos al estudio de compuestos de interés biológico, especialmente contaminantes, neurotransmisores y vitaminas. El primer reto está asociado a la fabricación de nuevos electrodos ópticamente transparentes de nanomateriales de carbono. El segundo se relaciona con el desarrollo de novedosos dispositivos espectroelectroquímicos basados en fibras ópticas que facilitan la realización de las medidas. Finalmente, el tercer reto conseguido consiste en la resolución cuantitativa de mezclas de sustancias cuyas señales muestran una elevadísima interferencia, en el seguimiento del pH durante un experimento espectroelectroquímico, y en la determinación de la concentración de ácido ascórbico directamente en un pomelo como primera aproximación a los experimentos in vivo.“Multipurpose Spectroelectrochemistry: Paving the Way for In Vivo Measurements” is the title of the doctoral thesis conducted by Jesús Garoz Ruiz under the direction of Drs. Aránzazu Heras and Álvaro Colina. This work, carried out at the Universidad de Burgos, addresses three main challenges to the study of compounds of biological interest, especially pollutants, neurotransmitters and vitamins, with optimal results. The first challenge is associated with the fabrication of new optically transparent electrodes of carbon nanomaterials. The second one is related to the development of novel spectroelectrochemical devices based on optical fibers that facilitate the performance of the experiments. Finally, the third goal achieved consists in the quantitative resolution of mixtures of substances whose signals show a high interference, in the monitoring of the pH during a spectroelectrochemical experiment, and in the determination of the ascorbic acid concentration directly in a grapefruit as a first approximation to in vivo experiments