Manel del Valle | Universitat Autònoma de Barcelona (original) (raw)

Papers by Manel del Valle

Research paper thumbnail of Voltammetric Resolution of Dopamine in Complex Mixtures Using Graphene-Modified Electrode and Artificial Neural Networks

Proceedings of the 5th International Symposium on Sensor Science (I3S 2017), 2017

Research paper thumbnail of Coupling of Sensors and Machine Learning Algorithms in the Qualitative Analysis of Wine

The 8th International Symposium on Sensor Science, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Research on the determination and analysis of organic load (Chemical Oxygen Demand) in wastewater utilizing copper/copper oxide nanoparticle electrodes and chemometrics tools

Research paper thumbnail of Sensors for the determination of organic load (Chemical Oxygen Demand) utilizing copper/copper oxide nanoparticle electrodes

Proceedings of 6th International Electronic Conference on Sensors and Applications, 2019

Chemical oxygen demand (COD) is a widely used parameter in analyzing and controlling the degree o... more Chemical oxygen demand (COD) is a widely used parameter in analyzing and controlling the degree of pollution in water. Methods of analysis based on electrochemical sensors are increasingly being used for COD quantitation because they could be simple, accurate, sensitive and environmentally friendly. Electro-oxidizing the organic contaminants to completely transform them into CO2 and H2O is considered the best method for COD estimation using sensors. In this sense, copper electrodes have been reported based on the fact that copper in alkaline media acts as a powerful electrocatalyst for oxidation of aminoacids and carbohydrates, which are believed to be the major culprits of organic pollution. In this work, three kinds of copper/copper oxide electrodes were studied that employed the cyclic voltammetry technique: electrodeposited copper nanoparticle electrode, copper nanoparticle–graphite composite electrode and copper oxide nanoparticle–graphite composite electrode. Actual COD estima...

Research paper thumbnail of Resolution of galactose, glucose, xylose and mannose in sugarcane bagasse employing a voltammetric electronic tongue formed by metals oxy-hydroxide/MWCNT modified electrodes

Sensors and Actuators B: Chemical, 2016

Second generation ethanol is produced from the carbohydrates released from the cell wall of bagas... more Second generation ethanol is produced from the carbohydrates released from the cell wall of bagasse and straw of sugarcane. The objective of this work is the characterization and application of a voltammetric electronic tongue using an array of glassy carbon electrodes modified with multi-walled carbon nanotubes containing metal (Paladium, Gold, Copper, Nickel and Cobalt,) oxy-hydroxide nanoparticles (GCE/MWCNT/MetalsOOH) towards a simpler analysis of carbohydrates (glucose, xylose, galactose and mannose). The Artificial Neural Network (ANN) based prediction model has resulted satisfactory for all carbohydrates and the obtained response had shown an adequate accuracy. In this manner 192 architectures were evaluated. The final architecture of the back-propagation ANN model had 36 input neurons, a hidden layer with 5 neurons and the tansig transfer function, an output layer with 4 neurons and the purelin transfer function. All species a comparison correlation coefficient of r ≥ 0.99 for the training subset and of r ≥ 0.96 for the test subset, being close to the ideal value.

Research paper thumbnail of Carbon Nanotubes as Suitable Electrochemical Platforms for Metalloprotein Sensors and Genosensors

Carbon Nanotubes - Growth and Applications, 2011

Research paper thumbnail of Wavelet neural networks to resolve the overlapping signal in the voltammetric determination of phenolic compounds

Talanta, 2008

Three phenolic compounds, i.e. phenol, catechol and 4-acetamidophenol, were simultaneously determ... more Three phenolic compounds, i.e. phenol, catechol and 4-acetamidophenol, were simultaneously determined by voltammetric detection of its oxidation reaction at the surface of an epoxy-graphite transducer. Because of strong signal overlapping, Wavelet Neural Networks (WNN) were used in data treatment, in a combination of chemometrics and electrochemical sensors, already known as the electronic tongue concept. To facilitate calibration, a set of samples (concentration of each phenol ranging from 0.25 to 2.5 mM) was prepared automatically by employing a Sequential Injection System. Phenolic compounds could be resolved with good prediction ability, showing correlation coefficients greater than 0.929 when the obtained values were compared with those expected for a set of samples not employed for training.

Research paper thumbnail of Flow-through pH-ISFET + reference-ISE as integrated detector in automated FIA determinations

Sensors and Actuators B: Chemical, 1992

Research paper thumbnail of Enhancing the electrochemical response of myoglobin with carbon nanotube electrodes

Nanotechnology, 2009

In this paper, the electrochemical behavior of different myoglobin-modified carbon electrodes is ... more In this paper, the electrochemical behavior of different myoglobin-modified carbon electrodes is evaluated. In particular, the performance of voltammetric biosensors made of forest-like carbon nanotubes, carbon nanotube composites and graphite composites is compared by monitoring mainly the electrocatalytic reduction of H(2)O(2) by myoglobin and their corresponding electroanalytical characteristics. Graphite composites showed the worst electroanalytical performance, exhibiting a small linear range, a limit of detection (LOD) of 9 x 10(-5) M and low sensitivity. However, it was found that the electrochemical response was enhanced with the use of carbon nanotube-based electrodes with LOD up to 5 x 10(-8) M, higher sensitivities and wider linear range response. On the one hand, in the case of the CNT epoxy composite, the improvement in the response can be mainly attributed to its more porous surface which allows the immobilization of higher amounts of the electroactive protein. On the other hand, in the case of the forest-like CNT electrodes, the enhancement is due to an increase in the electron transfer kinetics. These findings encourage the use of myoglobin-modified carbon nanotube electrodes as potential (bio)sensors of H(2)O(2) or O(2) in biology, microbiology and environmental fields.

Research paper thumbnail of Resolution of Heavy Metal Mixtures from Highly Overlapped ASV Voltammograms Employing a Wavelet Neural Network

Electroanalysis, 2009

This work describes the chemometric assisted ASV determination of three heavy metals in water (le... more This work describes the chemometric assisted ASV determination of three heavy metals in water (lead, copper and cadmium) in presence of thallium and indium as interfering species. Stripping was carried out in open atmosphere, employing a graphite-epoxy transducer as working electrode, without any surface regeneration after each analysis. The concentration range studied was from 0.4 to 20 ppm for both analytes and interferents. Due to the overlapping nature of the signals, a wavelet neural network (WNN) was used for deconvolution of the voltammogram. In order to validate the resolution capability, a k-fold cross validation procedure was performed. Mixtures of metals could be resolved with good prediction of their concentrations; obtained vs. expected comparison graphs exhibited, for a set of samples not employed for training, correlation values of 0.996 for lead, 0.989 for cadmium and 0.995 for copper.

Research paper thumbnail of Use of an Electronic Tongue Based on All-Solid-State Potentiometric Sensors for the Quantitation of Alkaline Ions

Research paper thumbnail of pH-ISFET with NMOS technology

Electroanalysis, 1991

The construction of a pH-ISFET (ion-selective field effect transistor) fabricated with standard n... more The construction of a pH-ISFET (ion-selective field effect transistor) fabricated with standard negative-channel MOS technology, compatible with complementary MOS technology, and using silicon nitride as a pH-sensitive material, is described. Its main analytical characteristics are discussed. The resulting calibration plot is linear over the pH range from 2 to 11, with a slope of 54 mV per pH unit.

Research paper thumbnail of Flow-through pH-ISFET as detector in automated determinations

Electroanalysis, 1991

The implementation of a pH-ISFET (ion-selective field effect transistor) planar chip in a flow-in... more The implementation of a pH-ISFET (ion-selective field effect transistor) planar chip in a flow-injection system by means of a specially designed flow cell and the application of the sensor to the analysis of volatile compounds is described. Ammonia and sulfur dioxide are determined by exploiting the advantages of the flow techniques combined with continuous gas diffusion. Initial species are converted

Research paper thumbnail of Determination of Ammonium Ion Employing an Electronic Tongue Based on Potentiometric Sensors

Analytical Letters, 2003

Abstract A method for determining ammonium ion concentration from complex aqueous samples is pres... more Abstract A method for determining ammonium ion concentration from complex aqueous samples is presented in this work. It does not need to eliminate chemical interferences, mainly sodium and potassium, because an array of potentiometric sensors with intrinsic ...

Research paper thumbnail of Evaluation of natural computation techniques in the modelling and optimization of a sequential injection flow system for colorimetric iron(III) determination

Analytica Chimica Acta, 1997

The present study shows and gives evidence of the applicability of natural computation techniques... more The present study shows and gives evidence of the applicability of natural computation techniques in the modelling and optimization of a sequential injection flow system of analysis for colorimetric iron(III) determination in water samples. The reaction with thiocyanate is used as reagent colour. A neural network consisting of two hidden layers, each one formed by eight neurons, was used to

Research paper thumbnail of Mathematical modelling of two-analyte sequential determinations by flow-injection sandwich techniques

Analytica Chimica Acta, 1991

Results obtained in the evaluation of a mathematical model for flow-injection sandwich systems, i... more Results obtained in the evaluation of a mathematical model for flow-injection sandwich systems, in which the sample is inserted between two different carrier solutions with the aid of an eight-way injection valve, are presented. The model considers the system as a tubular reactor with axially dispersed plug flow, where chemical kinetics have been included. Only a minimum of parameters are

Research paper thumbnail of Simultaneous determination of phenolic compounds by means of an automated voltammetric “electronic tongue”

Analytical and Bioanalytical Chemistry, 2005

This contribution describes the simultaneous determination of three phenolic compounds, o-cresol,... more This contribution describes the simultaneous determination of three phenolic compounds, o-cresol, p-chlorophenol and 4- chloro- 3- methylphenol, using direct oxidation and amperometric detection coupled by signal deconvolution, accomplished via chemometric methods. Direct oxidation of phenolic compounds is performed at the surface of an epoxy-graphite transducer, by linear scan voltammetry. Due to strong signal overlapping, artificial neural networks (ANNs) were used

Research paper thumbnail of Article Potentiometric Electronic Tongue to Resolve Mixtures of Sulfide and Perchlorate Anions

This work describes the use of an array of potentiometric sensors and an artificial neural networ... more This work describes the use of an array of potentiometric sensors and an artificial neural network response model to determine perchlorate and sulfide ions in polluted waters, by what is known as an electronic tongue. Sensors used have been all-solid-state PVC membrane selective electrodes, where their ionophores were different metal-phtalocyanine complexes with specific and anion generic responses. The study case illustrates the potential use of electronic tongues in the quantification of mixtures when interfering effects need to be counterbalanced: relative errors in determination of individual ions can be decreased typically from 25% to less than 5%, if compared to the use of a single proposed ion-selective electrode.

Research paper thumbnail of Application of an electronic tongue using potentiometric sensors to fertigation strategy in greenhouse cultivation

For actual needs of increasing crop production and quality in modern agriculture, fertigation is ... more For actual needs of increasing crop production and quality in modern agriculture, fertigation is an established approach to implement advanced control schemes. The basic idea of this strategy is to maintain the concentration of specific ions in the recirculated drainage water at a desired level for optimal global function. In this way, nutrients which are uptaken by the plants must be refilled, and the accumulation of undesired components avoided. For this operation, accurate knowledge of concentration levels of individual ions present in fertigation solution is a must.

Research paper thumbnail of Graphene for the Building of Electroanalytical Enzyme-Based Biosensors. Application to the Inhibitory Detection of Emerging Pollutants

Nanomaterials

Graphene and its derivates offer a wide range of possibilities in the electroanalysis field, main... more Graphene and its derivates offer a wide range of possibilities in the electroanalysis field, mainly owing to their biocompatibility, low-cost, and easy tuning. This work reports the development of an enzymatic biosensor using reduced graphene oxide (RGO) as a key nanomaterial for the detection of contaminants of emerging concern (CECs). RGO was obtained from the electrochemical reduction of graphene oxide (GO), an intermediate previously synthesized in the laboratory by a wet chemistry top-down approach. The extensive characterization of this material was carried out to evaluate its proper inclusion in the biosensor arrangement. The results demonstrated the presence of GO or RGO and their correct integration on the sensor surface. The detection of CECs was carried out by modifying the graphene platform with a laccase enzyme, turning the sensor into a more selective and sensitive device. Laccase was linked covalently to RGO using the remaining carboxylic groups of the reduction step ...

Research paper thumbnail of Voltammetric Resolution of Dopamine in Complex Mixtures Using Graphene-Modified Electrode and Artificial Neural Networks

Proceedings of the 5th International Symposium on Sensor Science (I3S 2017), 2017

Research paper thumbnail of Coupling of Sensors and Machine Learning Algorithms in the Qualitative Analysis of Wine

The 8th International Symposium on Sensor Science, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Research on the determination and analysis of organic load (Chemical Oxygen Demand) in wastewater utilizing copper/copper oxide nanoparticle electrodes and chemometrics tools

Research paper thumbnail of Sensors for the determination of organic load (Chemical Oxygen Demand) utilizing copper/copper oxide nanoparticle electrodes

Proceedings of 6th International Electronic Conference on Sensors and Applications, 2019

Chemical oxygen demand (COD) is a widely used parameter in analyzing and controlling the degree o... more Chemical oxygen demand (COD) is a widely used parameter in analyzing and controlling the degree of pollution in water. Methods of analysis based on electrochemical sensors are increasingly being used for COD quantitation because they could be simple, accurate, sensitive and environmentally friendly. Electro-oxidizing the organic contaminants to completely transform them into CO2 and H2O is considered the best method for COD estimation using sensors. In this sense, copper electrodes have been reported based on the fact that copper in alkaline media acts as a powerful electrocatalyst for oxidation of aminoacids and carbohydrates, which are believed to be the major culprits of organic pollution. In this work, three kinds of copper/copper oxide electrodes were studied that employed the cyclic voltammetry technique: electrodeposited copper nanoparticle electrode, copper nanoparticle–graphite composite electrode and copper oxide nanoparticle–graphite composite electrode. Actual COD estima...

Research paper thumbnail of Resolution of galactose, glucose, xylose and mannose in sugarcane bagasse employing a voltammetric electronic tongue formed by metals oxy-hydroxide/MWCNT modified electrodes

Sensors and Actuators B: Chemical, 2016

Second generation ethanol is produced from the carbohydrates released from the cell wall of bagas... more Second generation ethanol is produced from the carbohydrates released from the cell wall of bagasse and straw of sugarcane. The objective of this work is the characterization and application of a voltammetric electronic tongue using an array of glassy carbon electrodes modified with multi-walled carbon nanotubes containing metal (Paladium, Gold, Copper, Nickel and Cobalt,) oxy-hydroxide nanoparticles (GCE/MWCNT/MetalsOOH) towards a simpler analysis of carbohydrates (glucose, xylose, galactose and mannose). The Artificial Neural Network (ANN) based prediction model has resulted satisfactory for all carbohydrates and the obtained response had shown an adequate accuracy. In this manner 192 architectures were evaluated. The final architecture of the back-propagation ANN model had 36 input neurons, a hidden layer with 5 neurons and the tansig transfer function, an output layer with 4 neurons and the purelin transfer function. All species a comparison correlation coefficient of r ≥ 0.99 for the training subset and of r ≥ 0.96 for the test subset, being close to the ideal value.

Research paper thumbnail of Carbon Nanotubes as Suitable Electrochemical Platforms for Metalloprotein Sensors and Genosensors

Carbon Nanotubes - Growth and Applications, 2011

Research paper thumbnail of Wavelet neural networks to resolve the overlapping signal in the voltammetric determination of phenolic compounds

Talanta, 2008

Three phenolic compounds, i.e. phenol, catechol and 4-acetamidophenol, were simultaneously determ... more Three phenolic compounds, i.e. phenol, catechol and 4-acetamidophenol, were simultaneously determined by voltammetric detection of its oxidation reaction at the surface of an epoxy-graphite transducer. Because of strong signal overlapping, Wavelet Neural Networks (WNN) were used in data treatment, in a combination of chemometrics and electrochemical sensors, already known as the electronic tongue concept. To facilitate calibration, a set of samples (concentration of each phenol ranging from 0.25 to 2.5 mM) was prepared automatically by employing a Sequential Injection System. Phenolic compounds could be resolved with good prediction ability, showing correlation coefficients greater than 0.929 when the obtained values were compared with those expected for a set of samples not employed for training.

Research paper thumbnail of Flow-through pH-ISFET + reference-ISE as integrated detector in automated FIA determinations

Sensors and Actuators B: Chemical, 1992

Research paper thumbnail of Enhancing the electrochemical response of myoglobin with carbon nanotube electrodes

Nanotechnology, 2009

In this paper, the electrochemical behavior of different myoglobin-modified carbon electrodes is ... more In this paper, the electrochemical behavior of different myoglobin-modified carbon electrodes is evaluated. In particular, the performance of voltammetric biosensors made of forest-like carbon nanotubes, carbon nanotube composites and graphite composites is compared by monitoring mainly the electrocatalytic reduction of H(2)O(2) by myoglobin and their corresponding electroanalytical characteristics. Graphite composites showed the worst electroanalytical performance, exhibiting a small linear range, a limit of detection (LOD) of 9 x 10(-5) M and low sensitivity. However, it was found that the electrochemical response was enhanced with the use of carbon nanotube-based electrodes with LOD up to 5 x 10(-8) M, higher sensitivities and wider linear range response. On the one hand, in the case of the CNT epoxy composite, the improvement in the response can be mainly attributed to its more porous surface which allows the immobilization of higher amounts of the electroactive protein. On the other hand, in the case of the forest-like CNT electrodes, the enhancement is due to an increase in the electron transfer kinetics. These findings encourage the use of myoglobin-modified carbon nanotube electrodes as potential (bio)sensors of H(2)O(2) or O(2) in biology, microbiology and environmental fields.

Research paper thumbnail of Resolution of Heavy Metal Mixtures from Highly Overlapped ASV Voltammograms Employing a Wavelet Neural Network

Electroanalysis, 2009

This work describes the chemometric assisted ASV determination of three heavy metals in water (le... more This work describes the chemometric assisted ASV determination of three heavy metals in water (lead, copper and cadmium) in presence of thallium and indium as interfering species. Stripping was carried out in open atmosphere, employing a graphite-epoxy transducer as working electrode, without any surface regeneration after each analysis. The concentration range studied was from 0.4 to 20 ppm for both analytes and interferents. Due to the overlapping nature of the signals, a wavelet neural network (WNN) was used for deconvolution of the voltammogram. In order to validate the resolution capability, a k-fold cross validation procedure was performed. Mixtures of metals could be resolved with good prediction of their concentrations; obtained vs. expected comparison graphs exhibited, for a set of samples not employed for training, correlation values of 0.996 for lead, 0.989 for cadmium and 0.995 for copper.

Research paper thumbnail of Use of an Electronic Tongue Based on All-Solid-State Potentiometric Sensors for the Quantitation of Alkaline Ions

Research paper thumbnail of pH-ISFET with NMOS technology

Electroanalysis, 1991

The construction of a pH-ISFET (ion-selective field effect transistor) fabricated with standard n... more The construction of a pH-ISFET (ion-selective field effect transistor) fabricated with standard negative-channel MOS technology, compatible with complementary MOS technology, and using silicon nitride as a pH-sensitive material, is described. Its main analytical characteristics are discussed. The resulting calibration plot is linear over the pH range from 2 to 11, with a slope of 54 mV per pH unit.

Research paper thumbnail of Flow-through pH-ISFET as detector in automated determinations

Electroanalysis, 1991

The implementation of a pH-ISFET (ion-selective field effect transistor) planar chip in a flow-in... more The implementation of a pH-ISFET (ion-selective field effect transistor) planar chip in a flow-injection system by means of a specially designed flow cell and the application of the sensor to the analysis of volatile compounds is described. Ammonia and sulfur dioxide are determined by exploiting the advantages of the flow techniques combined with continuous gas diffusion. Initial species are converted

Research paper thumbnail of Determination of Ammonium Ion Employing an Electronic Tongue Based on Potentiometric Sensors

Analytical Letters, 2003

Abstract A method for determining ammonium ion concentration from complex aqueous samples is pres... more Abstract A method for determining ammonium ion concentration from complex aqueous samples is presented in this work. It does not need to eliminate chemical interferences, mainly sodium and potassium, because an array of potentiometric sensors with intrinsic ...

Research paper thumbnail of Evaluation of natural computation techniques in the modelling and optimization of a sequential injection flow system for colorimetric iron(III) determination

Analytica Chimica Acta, 1997

The present study shows and gives evidence of the applicability of natural computation techniques... more The present study shows and gives evidence of the applicability of natural computation techniques in the modelling and optimization of a sequential injection flow system of analysis for colorimetric iron(III) determination in water samples. The reaction with thiocyanate is used as reagent colour. A neural network consisting of two hidden layers, each one formed by eight neurons, was used to

Research paper thumbnail of Mathematical modelling of two-analyte sequential determinations by flow-injection sandwich techniques

Analytica Chimica Acta, 1991

Results obtained in the evaluation of a mathematical model for flow-injection sandwich systems, i... more Results obtained in the evaluation of a mathematical model for flow-injection sandwich systems, in which the sample is inserted between two different carrier solutions with the aid of an eight-way injection valve, are presented. The model considers the system as a tubular reactor with axially dispersed plug flow, where chemical kinetics have been included. Only a minimum of parameters are

Research paper thumbnail of Simultaneous determination of phenolic compounds by means of an automated voltammetric “electronic tongue”

Analytical and Bioanalytical Chemistry, 2005

This contribution describes the simultaneous determination of three phenolic compounds, o-cresol,... more This contribution describes the simultaneous determination of three phenolic compounds, o-cresol, p-chlorophenol and 4- chloro- 3- methylphenol, using direct oxidation and amperometric detection coupled by signal deconvolution, accomplished via chemometric methods. Direct oxidation of phenolic compounds is performed at the surface of an epoxy-graphite transducer, by linear scan voltammetry. Due to strong signal overlapping, artificial neural networks (ANNs) were used

Research paper thumbnail of Article Potentiometric Electronic Tongue to Resolve Mixtures of Sulfide and Perchlorate Anions

This work describes the use of an array of potentiometric sensors and an artificial neural networ... more This work describes the use of an array of potentiometric sensors and an artificial neural network response model to determine perchlorate and sulfide ions in polluted waters, by what is known as an electronic tongue. Sensors used have been all-solid-state PVC membrane selective electrodes, where their ionophores were different metal-phtalocyanine complexes with specific and anion generic responses. The study case illustrates the potential use of electronic tongues in the quantification of mixtures when interfering effects need to be counterbalanced: relative errors in determination of individual ions can be decreased typically from 25% to less than 5%, if compared to the use of a single proposed ion-selective electrode.

Research paper thumbnail of Application of an electronic tongue using potentiometric sensors to fertigation strategy in greenhouse cultivation

For actual needs of increasing crop production and quality in modern agriculture, fertigation is ... more For actual needs of increasing crop production and quality in modern agriculture, fertigation is an established approach to implement advanced control schemes. The basic idea of this strategy is to maintain the concentration of specific ions in the recirculated drainage water at a desired level for optimal global function. In this way, nutrients which are uptaken by the plants must be refilled, and the accumulation of undesired components avoided. For this operation, accurate knowledge of concentration levels of individual ions present in fertigation solution is a must.

Research paper thumbnail of Graphene for the Building of Electroanalytical Enzyme-Based Biosensors. Application to the Inhibitory Detection of Emerging Pollutants

Nanomaterials

Graphene and its derivates offer a wide range of possibilities in the electroanalysis field, main... more Graphene and its derivates offer a wide range of possibilities in the electroanalysis field, mainly owing to their biocompatibility, low-cost, and easy tuning. This work reports the development of an enzymatic biosensor using reduced graphene oxide (RGO) as a key nanomaterial for the detection of contaminants of emerging concern (CECs). RGO was obtained from the electrochemical reduction of graphene oxide (GO), an intermediate previously synthesized in the laboratory by a wet chemistry top-down approach. The extensive characterization of this material was carried out to evaluate its proper inclusion in the biosensor arrangement. The results demonstrated the presence of GO or RGO and their correct integration on the sensor surface. The detection of CECs was carried out by modifying the graphene platform with a laccase enzyme, turning the sensor into a more selective and sensitive device. Laccase was linked covalently to RGO using the remaining carboxylic groups of the reduction step ...