Llengües bioelectròniques en l'anàlisi dels polifenols del vi

El desenvolupament i ús d'una llengua bioelectrònica per a dur a terme la discriminació i quantificació de diferents polifenols (catecol, àcid cafeic i catequina) presents en el vi és l'objectiu d'una investigació duta a terme al Departament de Química de la UAB. En una primera aplicació, la discriminació d'aquests polifenols va tenir lloc en mostres sintètiques, mentre que en el següent pas es va treballar sobre mostres dopades utilitzant el vi com a matriu. Aquesta descriminació pot ser útil per a la indústria del vi.El desarrollo y uso de una lengua bioelectrónica para llevar a cabo la discriminación y cuantificación de diferentes polifenoles (catecol, ácido cafeico y catequina) presentes en el vino és el objetivo de esta investigación desarrollada por el Departamento de Química de la UAB. En una primera aplicación, la discriminación de estos tuvo lugar en muestras sintéticas, mientras que en el siguiente paso se trabajó sobre muestras dopadas utilizando el vino como matriz. Esta discriminación puede ser útil para la industria del vino

Dialysis and column chromatography for biomass pyrolysis liquids separation

Altres ajuts: acords transformatius de la UABIn the current study, a novel approach for separating value-added chemicals from pine wood residues' pyrolysis liquids (bio-oil) was effectively carried out. It combined two separation techniques used for the first time in this field: dialysis with water, methanol and acetone, and column chromatography with Amberlite™ XAD7 resin. This strategy made it possible to separate bio-oil into four fractions: (1) pyrolytic lignin, which can be utilized in the synthesis of resins, foams, electrodes, asphalt, etc. (2) acid-rich fraction, with particular relevance to the chemical industry, (3) antioxidant fraction, containing phenolic compounds, with a lot of interest for pharmaceutical and nutraceutical industry, and (4) a final fraction containing the most non-polar chemicals from bio-oil. Thus, it was possible to develop a process that allows the obtention of bioproducts from woody biomass, a residue obtained in significant quantities in the management of non-profitable forests, making a step forward within the context of circular economy and bioeconomy

Production and separation of value-added compounds from pine wood using pyrolysis and biorefinery techniques

Altres ajuts: acords transformatius de la UABAltres ajuts: LIFE Programme of the European Union for the project LIFE BIOREFFORMED (LIFE 19 ENV/ES/000544)Value-added compounds were obtained from pine wood bio-oil, converting it into a renewable source for several chemicals: acids (acetic acid), sugars (levoglucosan), furan derivatives (furfural) and phenolics (catechol, phenol, 4-propylguaiacol, vanillin). To achieve this, firstly a comparison of a direct pyrolysis at 500 °C versus a two-staged pyrolysis (300 °C and 500 °C) was made. It was determined that a two-staged pyrolysis ensue in the obtainment of less complex liquid fractions since it concentrates families of compounds in different phases of bio-oil, facilitating their subsequent separation. Secondly, two methodologies (A and B) were designed to establish a procedure for separating the various chemical groups present in bio-oil. Methodology A consisted of a first vacuum distillation followed by an extraction process that combined an alkaline extraction and a simple extraction with ethyl acetate. Methodology B consisted of a first extraction with trioctylamine and ethyl acetate followed by a vacuum distillation and an extraction with hot water. The results showed that methodology A was better for the separation of chemical compounds from bio-oil, obtaining one fraction with the carboxylic acid content and furan derivatives, a second fraction containing the phenolic compounds and a third fraction enriched with the sugar content

Electrochemical Biosensor Based on Optimized Biocomposite for Organophosphorus and Carbamates Pesticides Detection

Altres ajuts: Universitat Autònoma de Barcelona (UAB) for the award of PIF studentshipThis paper presents the characterization and optimization of biosensors based on graphite-epoxy which incorporates the enzyme acetylcholinesterase (AChE). By means of advanced electrochemical techniques, such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), the characterization and optimization of graphite-epoxy-AChE biosensors have been performed. In order to obtain sensitive electrodes, the optimal composition of the transducer material (graphite-epoxy-enzyme ratio) was studied. The optimization of the conductive particles distribution inside the biomaterial has allowed an improvement of the electrochemical properties. Optimal composition guarantees improving electrochemical properties required, such as high electron-transfer rate, high signal-to-noise ratio, and suitable sensitivity. The optimal biocomposite composition range was obtained between 16% and 17% of graphite and 0.12% of AChE. The biosensors were applied to the analysis of different pesticides, organophosphorus and carbamates, using indirect measurements based on enzymatic inhibition process. These optimized biosensors present detection limit one order of magnitude lower compared to the standard composition (nonoptimized) and allow achieving concentrations lower than the established ones by the pesticides regulation. Finally, spiked tap water samples with pesticides were analyzed with the optimized biosensors

Determination of total polyphenol index in wines employing a voltammetric electronic tongue

This work reports the application of a voltammetric electronic tongue system (ET) made from an array of modified graphite-epoxy composites plus a gold microelectrode in the qualitative and quantitative analysis of polyphenols found in wine. Wine samples were analyzed using cyclic voltammetry without any sample pretreatment. The obtained responses were preprocessed employing discrete wavelet transform (DWT) in order to compress and extract significant features from the voltammetric signals, and the obtained approximation coefficients fed a multivariate calibration method (artificial neural network-ANN-or partial least squares-PLS-) which accomplished the quantification of total polyphenol content. External test subset samples results were compared with the ones obtained with the Folin-Ciocalteu (FC) method and UV absorbance polyphenol index (I₂₈₀) as reference values, with highly significant correlation coefficients of 0.979 and 0.963 in the range from 50 to 2400 mg L⁻¹ gallic acid equivalents, respectively. In a separate experiment, qualitative discrimination of different polyphenols found in wine was also assessed by principal component analysis (PCA)

Electrochemical Biosensor Based on Optimized Biocomposite for Organophosphorus and Carbamates Pesticides Detection

Altres ajuts: Universitat Autònoma de Barcelona (UAB) for the award of PIF studentshipThis paper presents the characterization and optimization of biosensors based on graphite-epoxy which incorporates the enzyme acetylcholinesterase (AChE). By means of advanced electrochemical techniques, such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), the characterization and optimization of graphite-epoxy-AChE biosensors have been performed. In order to obtain sensitive electrodes, the optimal composition of the transducer material (graphite-epoxy-enzyme ratio) was studied. The optimization of the conductive particles distribution inside the biomaterial has allowed an improvement of the electrochemical properties. Optimal composition guarantees improving electrochemical properties required, such as high electron-transfer rate, high signal-to-noise ratio, and suitable sensitivity. The optimal biocomposite composition range was obtained between 16% and 17% of graphite and 0.12% of AChE. The biosensors were applied to the analysis of different pesticides, organophosphorus and carbamates, using indirect measurements based on enzymatic inhibition process. These optimized biosensors present detection limit one order of magnitude lower compared to the standard composition (nonoptimized) and allow achieving concentrations lower than the established ones by the pesticides regulation. Finally, spiked tap water samples with pesticides were analyzed with the optimized biosensors

Determination of total polyphenol index in wines employing a voltammetric electronic tongue

This work reports the application of a voltammetric electronic tongue system (ET) made from an array of modified graphite-epoxy composites plus a gold microelectrode in the qualitative and quantitative analysis of polyphenols found in wine. Wine samples were analyzed using cyclic voltammetry without any sample pretreatment. The obtained responses were preprocessed employing discrete wavelet transform (DWT) in order to compress and extract significant features from the voltammetric signals, and the obtained approximation coefficients fed a multivariate calibration method (artificial neural network-ANN-or partial least squares-PLS-) which accomplished the quantification of total polyphenol content. External test subset samples results were compared with the ones obtained with the Folin-Ciocalteu (FC) method and UV absorbance polyphenol index (I₂₈₀) as reference values, with highly significant correlation coefficients of 0.979 and 0.963 in the range from 50 to 2400 mg L⁻¹ gallic acid equivalents, respectively. In a separate experiment, qualitative discrimination of different polyphenols found in wine was also assessed by principal component analysis (PCA)