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

Raw stone material supply for upper pleistocene open air sites in Sierra de Atapuerca (Burgos, Spain)

Ponencia presentada en: VII Congreso Ibérico de Arqueometría, celebrado en Madrid del 8 al 10 de octubre de 2007En este artículo analizamos 415 muestras de sílex natural y arqueológico de la Sierra de Atapuerca (Burgos) mediante microscopia, espectrometría de masas y difracción de Rayos X con el objetivo de caracterizar los sílex de diferente formación existentes en la zona (neógeno y cretácico), inferir su ambiente genético y conocer las fuentes de aprovisionamiento de los cazadores-recolectores que explotan este espacio durante el Pleistoceno superior. Además se crea un modelo estadístico de clasificación mediante análisis discriminante lineal, support vector machines y k-nearest neighbour que nos permite diferenciar los sílex en función de su edad de formación.Microscopy, mass spectrometry and X-ray diffraction methods were used to analyse 415 samples of natural and archaeological flint from Sierra de Atapuerca (Burgos, Spain) in order to characterize the different types from Neogene and Cretaceous formations in the study area, infer their genetic context and ascertain the supply sources used by hunter-gatherers who exploited this area in the Upper Pleistocene. A statistical classification model was also designed using linear discriminatory analysis, support vector machines and k-nearest neighbour which permitted the differentiation of the flint based on their age of formation.Agradecemos a Carlos Díez la ayuda prestada para la realización de este trabajo y sus comentarios para mejorarlo; M.N. es becaria postdoctoral de la Cátedra Atapuerca (Fundación Atapuerca-Fundación Duques de Soria). Este artículo se redacta dentro del proyecto de investigación “El Pleistoceno y el Holoceno de la Sierra de Atapuerca: Paleobiología y Paleoeconomía de las poblaciones humanas del Pleistoceno y Holoceno III” CGL2006-13532-C03-03 de la Dirección General de Investigación del Ministerio de Educación y Ciencia, y del proyecto BU 01-04 “Gestión del territorio en el Paleolítico medio del área centroriental de Castilla y León por medio del estudio de fuentes y productos líticos” de la Consejería de Educación y Cultura de la Junta de Castilla y León

Multiamperometric-SERS detection of melamine on gold screen-printed electrodes

A new, simple and fast protocol to generate gold-based SERS substrates is presented in this work. Melamine is a compound widely used in the industry that can be toxic for humans if consumed even in low concentrations. EC-SERS is an excellent alternative to classical methods to detect and quantify this compound because Raman spectroscopy provides a fingerprint of the molecules, providing very good sensitivity. In this work, timeresolved Raman spectroelectrochemistry is employed to generate a SERS substrate and to detect melamine, all in a single experiment. The dynamic character of this technique provides valuable information about the interaction of the molecule with the generated substrate. An optimization of the spectroelectrochemical method based on a multi-pulse amperometric detection has been performed. The new protocol presented in this work shows significant figures of merit in a very short experiment time, just 25 s.Authors acknowledge the financial support from Agencia Estatal de Investigación/Ministerio de Ciencia e Innovacion /10.13039/ 501100011033 (Grant PID2020-113154RB-C21) and Ministerio de Ciencia, Innovación y Universidades (Grant RED2018-102412-T). W. Ch. thanks JCyL for his postdoctoral fellowship (Grant BU297P18). S.H. and M.P-E. thank JCyL and European Social Fund for their predoctoral fellowships

Dataset of the work “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 Investigacion (MCIN/AEI/ 10.13039/501100011033, PID2020-113154RB-C21) and Ministerio de Ciencia, Innovacion y Universidades (Grant RED2018-102412-T). Fabiola Olmo is grateful for the contract funded by Junta de Castilla y Leon, the European Social Fund, and the Youth Employment Initiative

Dataset of the work “Simultaneous Raman and reflection UV/Vis absorption spectroelectrochemistry”

In the present work, a new combination of Raman and ultraviolet and visible (UV/Vis) absorption spectroelectrochemistry in reflection mode is proposed. The new experimental setup allows obtaining the two kinds of spectroscopic data without interferences concomitantly with the electrochemical information. To the best of our knowledge, it is the first time to report the simultaneous obtention of electrochemical, electronic, and vibrational information in the same experiment. This new combination provides time-resolved information about the processes that are taking place on the electrode/solution interface which has significant implications in different fields of chemistry, such as modification of electrodes, studies of electrocatalytic reaction mechanisms, development of sensors, among others. Two different systems were used to demonstrate the advantages and capabilities of the brand-new technique, namely, the oxidation of potassium ferrocyanide, an out-sphere system that is usually employed in the validation of SEC techniques, and the electrochemical-surface enhanced Raman spectroscopy (EC-SERS) detection of crystal violet by in-situ formation of the silver SERS substrate, where the UV/Vis spectra were used to follow the formation of the SERS substrate, whereas the Raman response of a probe molecule was used to confirm either the formation of a nanostructured surface and to obtain the fingerprint of the molecule with a high time resolution. The brand-new experimental setup has shown to be useful, versatile, robust, compact, and easy to use for future applications.Authors acknowledge the financial support from Ministerio de Ciencia e Innovacion (No. PID2020-113154RB-C21), Ministerio de Economía, Industria y Competitividad (No. CTQ2017-83935-RAEI/FEDERUE), Junta de Castilla y Leon (No. BU297P18), and Ministerio de Ciencia, Innovacion y Universidades (No. RED2018-102412-T). J.V.P-R acknowledges Spanish Ministry of Economy, Industry, and Competitiveness for the Juan de la Cierva postdoctoral (No. FJCI-2017-32458) and the University of Alcala (No. CCG19/CC-071). S.H. thanks JCyL and European Social Fund for her predoctoral fellowship

Dataset of the work “Multiamperometric-SERS detection of melamine on gold screen-printed electrodes”

A new, simple and fast protocol to generate gold-based SERS substrates is presented in this work. Melamine is a compound widely used in the industry that can be toxic for humans if consumed even in low concentrations. EC-SERS is an excellent alternative to classical methods to detect and quantify this compound because Raman spectroscopy provides a fingerprint of the molecules, providing very good sensitivity. In this work, time-resolved Raman spectroelectrochemistry is employed to generate a SERS substrate and to detect melamine, all in a single experiment. The dynamic character of this technique provides valuable information about the interaction of the molecule with the generated substrate. An optimization of the spectroelectrochemical method based on a multi-pulse amperometric detection has been performed. The new protocol presented in this work shows significant figures of merit in a very short experiment time, just 25 s.Authors acknowledge the financial support from Agencia Estatal de Investigación/Ministerio de Ciencia e Innovacion /10.13039/501100011033 (Grant PID2020-113154RB-C21) and Ministerio de Ciencia, Innovación y Universidades (Grant RED2018-102412-T). W. Ch. thanks JCyL for his postdoctoral fellowship (Grant BU297P18). S.H. and M.P-E. thank JCyL and European Social Fund for their predoctoral fellowships

Raman spectroelectrochemical determination of clopyralid in tap water

Clopyralid is a common herbicide used all around the world that can be dissolved in the rain stream and accumulate in underground water with the potential threat of reaching drinking water. Many methodologies have been proposed to perform quantitative analysis of this compound but, to this day, no Raman detection of clopyralid has been carried out. Here, a novel methodology to quantify clopyralid, based on Electrochemical Surface Oxidation-Enhanced Raman Scattering (EC-SOERS), is developed, using disposable silver screen-printed electrodes as substrate. The optimization of the electrolytic media is carried out, searching for the conditions where a maximum Raman enhancement is obtained. Moreover, a study about the effect of various interfering compounds, which could be present in water, on the clopyralid Raman response is performed. The results demonstrate that the presented methodology allows the determination of clopyralid in the micromolar range in tap water without any purification or preconcentration step, requiring few minutes to perform the measurement of each sample.Authors acknowledge Ministerio de Ciencia e Innovación and Agencia Estatal de Investigación (MCIN/AEI/10.13039/501100011033, PID2020-113154RB-C21), Junta de Castilla y León (Grant BU297P18) and Ministerio de Ciencia, Innovación y Universidades (RED2018–102412-T) for the support of this work. Martín Perez and Sheila Hernández acknowledge Junta de Castilla y Leon for their predoctoral contracts

Dataset of the work “Raman spectroelectrochemical determination of clopyralid in tap water”

Clopyralid is a common herbicide used all around the world that can be dissolved in the rain stream and accumulate in underground water with the potential threat of reaching drinking water. Many methodologies have been proposed to perform quantitative analysis of this compound but, to this day, no Raman detection of clopyralid has been carried out. Here, a novel methodology to quantify clopyralid, based on Electrochemical Surface Oxidation-Enhanced Raman Scattering (EC-SOERS), is developed, using disposable silver screen-printed electrodes as substrate. The optimization of the electrolytic media is carried out, searching for the conditions where a maximum Raman enhancement is obtained. Moreover, a study about the effect of various interfering compounds, which could be present in water, on the clopyralid Raman response is performed. The results demonstrate that the presented methodology allows the determination of clopyralid in the micromolar range in tap water without any purification or preconcentration step, requiring few minutes to perform the measurement of each sample.Authors acknowledge Ministerio de Ciencia e Innovacion and Agencia Estatal de Investigacion (MCIN/AEI/10.13039/501100011033, PID2020-113154RB-C21), Junta de Castilla y Leon (Grant BU297P18) and Ministerio de Ciencia, Innovacion y Universidades (RED2018–102412-T) for the support of this work. Martín Perez and Sheila Hernandez acknowledge Junta de Castilla y Leon for their predoctoral contracts

Interfacial doping of carbon nanotubes at the polarisable organic/water interface: a liquid/liquid pseudo-capacitor

The electrochemical reactivity of single-walled carbon nanotube (SWCNT) films, assembled at a polarisable organic/water interface, has been probed using model redox species. Electrons generated by the oxidation of organic 1,10-dimethylferrocene (DMFc) to DMFc+ can be transferred through the assembled SWCNT layer and reduce aqueous ferricyanide (Fe(CN)6 3 ) to ferrocyanide (Fe(CN)6 4 ), with a doping interaction observed. Several electrochemical techniques, including cyclic voltammetry and electrochemical impedance spectroscopy (EIS), were employed to confirm that the model redox couples dope/charge the SWCNTs. In situ Raman spectro-electrochemistry was also applied to verify the charge transfer processes occurring at the assembled SWCNT films and confirm that the doping effect of the carbon nanotubes is initiated by electrochemical reactions. This doping interaction indicated that the adsorbed SWCNT films can act as a pseudo-capacitor, showing a high area-normalised capacitance. The deeper understanding of the electrochemical properties of SWCNTs, gained from this study, will help determine the performance of this material for practical applications.U.K. EPSRC (grants EP/K007033/1, EP/ K039547/1, EP/K016954/1) and Ministerio de Economía y Competitividad de España (CTQ2014-55583-R, CTQ2014-61914- EXP

El Paleolítico Medio en el Valle del Arlanza (Burgos). Los sitios de La Ermita, Millán y La Mina

Se revisan los sitios clásicos del Paleolítico medio, La Ermita y Millán, añadiendo la información del cercano yacimiento La Mina, todos en el valle del Arlanza (Hortigüela, Burgos). Se realizan nuevas dataciones, se prospecta y analizan las materias primas con ICP-MS, se realiza un estudio zooarqueológico y describimos los productos líticos, incluyendo los cantos no tallados y el conjunto inédito de Millán superficie. Las dataciones demuestran una larga ocupación del valle en las fases templadas del EIO 3 por parte de grupos humanos que usan las cuevas como campamentos de corta duración, generalmente estacional. El aprovisionamiento de materias líticas es local, con uso exhaustivo del sílex. Se realiza una caza de amplio espectro en todos los biotopos aledaños, con una particular búsqueda de las pieles y cueros de los animales. Se infiere una explotación radial e intensa sobre el valle del Arlanza.Two classic Middle Palaeolithic sites, La Ermita and Millán were revised, together with additional information from the nearby La Mina site, all in the Arlanza River valley (Hortigüela, Burgos, Spain). New dating and prospecting work was done, raw materials were studied using ICP-MS, a zooarchaeological study was conducted and we describe the stone products, including unworked stones and the unpublished Millán surface assemblage. The datings indicate long-term occupation of the valley in the temperate phases of OIS by human groups that used the caves as short-term campsites (usually seasonal). Stone material supplies were local, with exhaustive use of flint. Broad spectrum hunting was done in all the surrounding biotopes, including specific searches for animal skins and hides. We infer intense, radial exploitation of the Arlanza Valley.Agradecemos el trabajo e ideas aportadas por los editores y revisores de este volumen. Trabajo enmarcado en el proyecto “Gestión del territorio en el Paleolítico medio del área centroriental de Castilla y León por medio del estudio de fuentes y productos líticos” de la Consejería de Educación de la Junta de Castilla y León, con ayudas del Proyecto CGL2006-13532-C03/BTE. R.A. es becario de la Fundación Siglo para las Artesen Castilla y León y M.N. es becaria de la Cátedra Atapuerca (Fundación Duques de Soria y Fundación Atapuerca). Agradecemos al personal del MAN y del Museo de Salas de los Infantes los permisos y atenciones dispensadas