Potentiometric multisensor system for urine analysis. Machine learning algorithms for urine s... more Potentiometric multisensor system for urine analysis. Machine learning algorithms for urine samples classification. Non-invasive prostate cancer detection with high sensitivity and specificity.
When it comes to address quantitative analysis in complex mixtures, Partial Least Squares (PLS) i... more When it comes to address quantitative analysis in complex mixtures, Partial Least Squares (PLS) is often referred to as a standard first-order multivariate calibration method. The set of samples used to build the PLS regression model should ideally be large and representative to produce reliable predictions. In practice, however, the large number of calibration samples is not always affordable and the choice of these samples should be handled with care as it can significantly affect the accuracy of the predictive model. Correlation constrained multivariate curve resolution (CC-MCR) is an alternative regression method for first-order datasets where, unlike PLS, calibration and prediction stages are performed iteratively and optimized under constraints until the decomposition meets the convergence criterion. Both calibration and test samples are fitted into a unique bilinear model so that the number of calibration samples is no longer a critical issue. In this paper we demonstrate that under certain conditions CC-MCR models can provide for reasonable predictions in quantitative analysis of complex mixtures even when only three calibration samples are employed. The latter are defined as samples having the minimum, the maximum and the average concentration, providing for a simple and rapid strategy to build reliable calibration model. The feasibility of three-point multivariate calibration approach was assessed with several case studies featuring mixtures of different analytes in presence of interfering species. Satisfactory predictions with relative errors in the range 3-15% were achieved and good agreement with classical PLS models built from a larger set of calibration samples was observed.
The procedure for transfer of calibration models between different analytical methods is suggeste... more The procedure for transfer of calibration models between different analytical methods is suggested. It is based on the direct standardization (DS) algorithm earlier suggested for data conversion between physically different instruments of the same type. As a result, multivariate regression models obtained e.g. for NIR spectroscopic measurements in one wavelength range can be successfully applied for predictions from the data obtained with another NIR spectrometer in another wavelength range. The performance of the suggested method was tested with two simulated and two real datasets. In the latter case calibration models constructed for energy-dispersive X-ray fluorescence, UV-Vis spectrometry and NIR spectrometry were addressed. The observed performance of the method implies that it can have a broad range of possible applications in analytical chemistry; some of them are suggested in the paper.
There are certain issues in e-tongue research which precludes wide adoption of these systems in r... more There are certain issues in e-tongue research which precludes wide adoption of these systems in routine analytical practice. An important problem relates to sensor readings' drift which may invalidate corresponding multivariate calibration. Invalidation of established multivariate classification and regression models during a certain period of time leads to necessity of frequent e-tongue system recalibration requiring significant investment of time and efforts. An alternative approach can be based on mathematical sensor drift correction using sensor responses in certain standard solutions which are measured with required periodicity. In this study we show that application of univariate single sensor standardization approach (similar to single wavelength standardization suggested in spectroscopy) can significantly improve precision of both regression and classification models and can extend calibration lifetime up to the period of over two months compared with two weeks for raw uncorrected data. As a case study analysis of microcystins in water samples with potentiometric 2 e-tongue was addressed in two aspects: quantitative microcystins concentration evaluation and classification of samples into toxic and non-toxic ones.
The potentiometric E-tongue system was employed for water toxicity estimation in terms of cyanoba... more The potentiometric E-tongue system was employed for water toxicity estimation in terms of cyanobacterial microcystin toxins (MCs) detection. The data obtained from E-tongue were correlated to the MCs content detected by the standard chromatographic technique UHPLC-DAD (Ultra High Performance Liquid Chromatography with Diode Array Detector), as far as by the colorimetric enzymatic approach. The prediction of MCs released by toxic Microcystis aeruginosa strains was possible with Root Mean Squared Error of Validation (RMSEV) lower or very close to 1 µg/L, the provisional guideline value of WHO for MCs content in potable waters. The application of E-tongue system opens up a new perspective offset for fast and inexpensive analysis in the field of environmental monitoring, offering also the possibility to distinguish toxin producing and non-toxic M. aeruginosa strains present in potable water.
A novel smartphone-based CD-spectrometer (SCDS) was developed for high sensitive and cost-effecti... more A novel smartphone-based CD-spectrometer (SCDS) was developed for high sensitive and cost-effective colorimetric analysis. The SCDS system integrates with a CD segment for transmission grating with the advantage of cost-effective and simplicity. The SCDS employed HSV model and utilized the overall intensity for the absorbance measurement to promote the sensitivity. A high sensitive and specific system using TMB-MnO 2 reaction for ascorbic acid detection was established with the SCDS.
An electronic tongue comprising 21 potentiometric chemical sensors with pattern recognition tools... more An electronic tongue comprising 21 potentiometric chemical sensors with pattern recognition tools was used for the rapid off-line monitoring of batch Escherichia coli fermentations. The electronic tongue was capable of monitoring the changes in the media composition as the fermentation progressed, and could correlate this with an increase in biomass. The electronic tongue was also able to monitor the increase in organic acids, especially acetic acid, throughout the fermentation. This technique clearly shows promise as a rapid tool for fermentation monitoring.
... Attention is paid to original non-specific solid-state chemical sensors with chalcogenide gla... more ... Attention is paid to original non-specific solid-state chemical sensors with chalcogenide glass membranes. It has been demonstrated that inorganic sensing materials can be quite useful for «electronic tongue» both for artificial taste recognition and determination of component ...
Page 1. Cross Sensitivity of Cation-Selective Film Sensors Based on Polyvinyl Chloride AV Legin, ... more Page 1. Cross Sensitivity of Cation-Selective Film Sensors Based on Polyvinyl Chloride AV Legin, AM Rudnitskaya, AL Smirnova, LB L'vova, and Yu. G. Vlasov St. Petersburg State University, St. Petersburg, Russia Received June 20, 1998 ...
A variety of transition metals, e.g., copper, zinc, cadmium, lead, etc. are widely used in indust... more A variety of transition metals, e.g., copper, zinc, cadmium, lead, etc. are widely used in industry as components for wires, coatings, alloys, batteries, paints and so on. The inevitable presence of transition metals in industrial processes implies the ambition of developing a proper analytical technique for their adequate monitoring. Most of these elements, especially lead and cadmium, are acutely toxic for biological organisms. Quantitative determination of these metals at low activity levels in different environmental and industrial samples is therefore a vital task. A promising approach to achieve an at-side or on-line monitoring on a miniaturized and cost efficient way is the combination of a common potentiometric sensor array with heavy metal-sensitive thin-film materials, like chalcogenide glasses and polymeric materials, respectively.
New polymeric sensors with high sensitivity to cations of transition metals and lanthanides in ac... more New polymeric sensors with high sensitivity to cations of transition metals and lanthanides in acid media are suggested. The role of active substances in the polymeric membranes of the sensors is played by diamides of dipicolinic acid with various structures, which are compounds exhibiting a high extraction capacity for various metals.
ABSTRACT New polymeric electrochemical sensors for determining the content of lead were suggested... more ABSTRACT New polymeric electrochemical sensors for determining the content of lead were suggested. As the active substance of the polymeric membranes of the sensors was used N,N′-tetrabutyldipicolinamide, the compound exhibiting a high extractive capacity for heavy metal ions. The selectivity of the sensors with respect to lead ions in the presence of copper, cadmium, and zinc in a considerable excess was studied.
The main types of modern multisensor systems of the The main types of modern multisensor systems ... more The main types of modern multisensor systems of the The main types of modern multisensor systems of the electronic tongue type as well as the sensitive materials and sensors electronic tongue type as well as the sensitive materials and sensors (transducers) employed in such systems are considered. The most (transducers) employed in such systems are considered. The most commonly used analytical applications of the electronic tongue commonly used analytical applications of the electronic tongue including recognition and classification of various liquid media, including recognition and classification of various liquid media, quantitative analysis, process monitoring and taste assessment of quantitative analysis, process monitoring and taste assessment of foodstuffs are discussed. The bibliography includes 84 references foodstuffs are discussed. The bibliography includes 84 references. .
A variety of new chemical sensors for determination of triple charged rare earth (RE) metal catio... more A variety of new chemical sensors for determination of triple charged rare earth (RE) metal cations from lanthanum(III) to lutetium(III) (lanthanides) has been developed and studied. Well-known extractants-bidentate neutral organophosphorous compounds, such as methylene diphosphine dioxides and carbamoylmethylphosphine oxides and tetraoctyl-3-oxapentanediamide (TODGA) were used as neutral ligands in the polymeric sensor membranes. It was found that addition of certain substances that are called "anionic modifiers" in sensor terminology (tetrabistrifluoromethylphenyl-borate (TFPB), chlorinated cobalt dicarbollide (CCD)) often results in increase of sensor sensitivity to lanthanides. Different sensors based on the extractants exhibit remarkable sensitivity to RE metal cations and their selectivity (cross-sensitivity) can be widely governed by changing the composition of the membranes. Chemical sensors based on the extractants show good promise for analysis of RE mixtures in complex solutions containing various other components. The developed sensors can be particularly interesting for the analysis of highly radioactive liquid waste (HLW).
nanosheets as the biomimetic oxidase for rapid and sensitive oxalate detection combining with bio... more nanosheets as the biomimetic oxidase for rapid and sensitive oxalate detection combining with bionic E-eye, Biosensors and Bioelectronic,
Multisensor systems for liquid analysis based on chemical sensor arrays and pattern recognition, ... more Multisensor systems for liquid analysis based on chemical sensor arrays and pattern recognition, which are now widely known as 'electronic tongues', represent one of the most rapidly emerging and exciting fields of non-classical analytics during the last decade. This chapter presents an overview of the research and development of electronic tongue systems and describes various sensors, sensor arrays, and their numerous applications. A sound basis for electronic tongues was provided by the extensive development of well-known selective sensors, especially electrochemical, and biological inspirations originating from sensory systems of mammalians. The up-to-date achievements of various scientific groups working in this field are reviewed. The performance of electronic tongues in the tasks of recognition (classification, identification, discrimination) of multicomponent media is considered. A useful option of multicomponent quantitative analysis with the help of electronic tongues is also reported. The correlation between the output of an electronic tongue and human sensory assessments of food flavor made by taste panel opens up an exciting possibility of measuring and quantifying the taste and flavor of foods. Application areas of the electronic tongue systems, including quality control of foodstuffs, clinical, industrial and environmental analysis, are surveyed. Future prospects for research and development of electronic tongues are discussed.
An electronic tongue based on the transient response of an array of non-specific-response potenti... more An electronic tongue based on the transient response of an array of non-specific-response potentiometric sensors was developed. A sequential injection analysis (SIA) system was used in order to automate its training and operation. The use of the transient recording entails the dynamic nature of the sensor's response, which can be of high information content, of primary ions and also of interfering ions; these may better discriminated if the kinetic resolution is added. This work presents the extraction of significant information contained in the transient response of a sensor array formed by five all-solid-state potentiometric sensors. The tool employed was the Fourier transform, from which a number of coefficients were fed into an artificial neural network (ANN) model, used to perform a quantitative multidetermination. The studied case was the analysis of mixtures of calcium, sodium and potassium. Obtained performance is compared with the more traditional automated electronic tongue using final steady-state potentials.
The potential of multisensor array in continuous on-line monitoring of processed water quality at... more The potential of multisensor array in continuous on-line monitoring of processed water quality at aeration plant is explored. The responses of 23 potentiometric sensors were continuously registered every seven seconds through the 26 days of experiment in a special container having connection with outlet water line of the aeration plant. Using chemometric tools it is shown that potentiometric "electronic tongue" is capable of evaluation of two important parameters of water quality: ammonium nitrogen and nitrate nitrogen. Unlike traditional sampling-based analysis the results of multisensor are available immediately in a real-time mode. Moreover, the achieved precision is sufficient to monitor possible alarm events. The employment of topological data analysis allowed for exploration of the very large dataset (295,828 measurements) accumulated through the long period of continuous measurements with sensors and for judgment on stability of water quality.
The electronic tongue (ET) multisensor system has been employed for the detection of metal-oxygen... more The electronic tongue (ET) multisensor system has been employed for the detection of metal-oxygen cluster anions (polyoxometalates) containing vanadium (IV/V) atoms. Sensitivity of a variety of potentiometric chemical sensors with plasticized polyvinyl chloride and chalcogenide glass membranes was evaluated with respect to vanadyl/vanadate ions, decavanadate and a series of Keggin-type polyoxometalates (POM) such as ␣-[SiW 11 V IV O 40 ] 6− , ␣-[SiW 11 V V O 40 ] 5− , ␣-[BW 11 V IV O 40 ] 7− , ␣-[BW 11 V V O 40 ] 6− , ␣-[PW 11 V IV O 40 ] 5− and ␣-[PW 12−n V n V O 40 ] (3+n)− (n = 1, 2, 3). Sensor's responses to vanadium complexes were evaluated in the pH range of 2.4-6.5 and a set of sensors appropriate for detecting a variety of vanadium species was selected. Such sensor array was able to distinguish different vanadium complexes allowing their simultaneous quantification in binary (V(IV)/V(V)) mixtures. The vanillyl alcohol oxidation with ␣-[SiW 11 V V O 40 ] 5− was monitored using ET to evaluate the capacity of proposed analytic system to detect simultaneously V(IV)/V(V) in POM under dynamic equilibrium. ET was demonstrated to be a promising tool for the discrimination and quantification of vanadium-containing POMs at different oxidation states. In particular, such a system could represent a significant interest for the mechanistic studies of redox reactions with POMs.
Potentiometric multisensor system for urine analysis. Machine learning algorithms for urine s... more Potentiometric multisensor system for urine analysis. Machine learning algorithms for urine samples classification. Non-invasive prostate cancer detection with high sensitivity and specificity.
When it comes to address quantitative analysis in complex mixtures, Partial Least Squares (PLS) i... more When it comes to address quantitative analysis in complex mixtures, Partial Least Squares (PLS) is often referred to as a standard first-order multivariate calibration method. The set of samples used to build the PLS regression model should ideally be large and representative to produce reliable predictions. In practice, however, the large number of calibration samples is not always affordable and the choice of these samples should be handled with care as it can significantly affect the accuracy of the predictive model. Correlation constrained multivariate curve resolution (CC-MCR) is an alternative regression method for first-order datasets where, unlike PLS, calibration and prediction stages are performed iteratively and optimized under constraints until the decomposition meets the convergence criterion. Both calibration and test samples are fitted into a unique bilinear model so that the number of calibration samples is no longer a critical issue. In this paper we demonstrate that under certain conditions CC-MCR models can provide for reasonable predictions in quantitative analysis of complex mixtures even when only three calibration samples are employed. The latter are defined as samples having the minimum, the maximum and the average concentration, providing for a simple and rapid strategy to build reliable calibration model. The feasibility of three-point multivariate calibration approach was assessed with several case studies featuring mixtures of different analytes in presence of interfering species. Satisfactory predictions with relative errors in the range 3-15% were achieved and good agreement with classical PLS models built from a larger set of calibration samples was observed.
The procedure for transfer of calibration models between different analytical methods is suggeste... more The procedure for transfer of calibration models between different analytical methods is suggested. It is based on the direct standardization (DS) algorithm earlier suggested for data conversion between physically different instruments of the same type. As a result, multivariate regression models obtained e.g. for NIR spectroscopic measurements in one wavelength range can be successfully applied for predictions from the data obtained with another NIR spectrometer in another wavelength range. The performance of the suggested method was tested with two simulated and two real datasets. In the latter case calibration models constructed for energy-dispersive X-ray fluorescence, UV-Vis spectrometry and NIR spectrometry were addressed. The observed performance of the method implies that it can have a broad range of possible applications in analytical chemistry; some of them are suggested in the paper.
There are certain issues in e-tongue research which precludes wide adoption of these systems in r... more There are certain issues in e-tongue research which precludes wide adoption of these systems in routine analytical practice. An important problem relates to sensor readings' drift which may invalidate corresponding multivariate calibration. Invalidation of established multivariate classification and regression models during a certain period of time leads to necessity of frequent e-tongue system recalibration requiring significant investment of time and efforts. An alternative approach can be based on mathematical sensor drift correction using sensor responses in certain standard solutions which are measured with required periodicity. In this study we show that application of univariate single sensor standardization approach (similar to single wavelength standardization suggested in spectroscopy) can significantly improve precision of both regression and classification models and can extend calibration lifetime up to the period of over two months compared with two weeks for raw uncorrected data. As a case study analysis of microcystins in water samples with potentiometric 2 e-tongue was addressed in two aspects: quantitative microcystins concentration evaluation and classification of samples into toxic and non-toxic ones.
The potentiometric E-tongue system was employed for water toxicity estimation in terms of cyanoba... more The potentiometric E-tongue system was employed for water toxicity estimation in terms of cyanobacterial microcystin toxins (MCs) detection. The data obtained from E-tongue were correlated to the MCs content detected by the standard chromatographic technique UHPLC-DAD (Ultra High Performance Liquid Chromatography with Diode Array Detector), as far as by the colorimetric enzymatic approach. The prediction of MCs released by toxic Microcystis aeruginosa strains was possible with Root Mean Squared Error of Validation (RMSEV) lower or very close to 1 µg/L, the provisional guideline value of WHO for MCs content in potable waters. The application of E-tongue system opens up a new perspective offset for fast and inexpensive analysis in the field of environmental monitoring, offering also the possibility to distinguish toxin producing and non-toxic M. aeruginosa strains present in potable water.
A novel smartphone-based CD-spectrometer (SCDS) was developed for high sensitive and cost-effecti... more A novel smartphone-based CD-spectrometer (SCDS) was developed for high sensitive and cost-effective colorimetric analysis. The SCDS system integrates with a CD segment for transmission grating with the advantage of cost-effective and simplicity. The SCDS employed HSV model and utilized the overall intensity for the absorbance measurement to promote the sensitivity. A high sensitive and specific system using TMB-MnO 2 reaction for ascorbic acid detection was established with the SCDS.
An electronic tongue comprising 21 potentiometric chemical sensors with pattern recognition tools... more An electronic tongue comprising 21 potentiometric chemical sensors with pattern recognition tools was used for the rapid off-line monitoring of batch Escherichia coli fermentations. The electronic tongue was capable of monitoring the changes in the media composition as the fermentation progressed, and could correlate this with an increase in biomass. The electronic tongue was also able to monitor the increase in organic acids, especially acetic acid, throughout the fermentation. This technique clearly shows promise as a rapid tool for fermentation monitoring.
... Attention is paid to original non-specific solid-state chemical sensors with chalcogenide gla... more ... Attention is paid to original non-specific solid-state chemical sensors with chalcogenide glass membranes. It has been demonstrated that inorganic sensing materials can be quite useful for «electronic tongue» both for artificial taste recognition and determination of component ...
Page 1. Cross Sensitivity of Cation-Selective Film Sensors Based on Polyvinyl Chloride AV Legin, ... more Page 1. Cross Sensitivity of Cation-Selective Film Sensors Based on Polyvinyl Chloride AV Legin, AM Rudnitskaya, AL Smirnova, LB L'vova, and Yu. G. Vlasov St. Petersburg State University, St. Petersburg, Russia Received June 20, 1998 ...
A variety of transition metals, e.g., copper, zinc, cadmium, lead, etc. are widely used in indust... more A variety of transition metals, e.g., copper, zinc, cadmium, lead, etc. are widely used in industry as components for wires, coatings, alloys, batteries, paints and so on. The inevitable presence of transition metals in industrial processes implies the ambition of developing a proper analytical technique for their adequate monitoring. Most of these elements, especially lead and cadmium, are acutely toxic for biological organisms. Quantitative determination of these metals at low activity levels in different environmental and industrial samples is therefore a vital task. A promising approach to achieve an at-side or on-line monitoring on a miniaturized and cost efficient way is the combination of a common potentiometric sensor array with heavy metal-sensitive thin-film materials, like chalcogenide glasses and polymeric materials, respectively.
New polymeric sensors with high sensitivity to cations of transition metals and lanthanides in ac... more New polymeric sensors with high sensitivity to cations of transition metals and lanthanides in acid media are suggested. The role of active substances in the polymeric membranes of the sensors is played by diamides of dipicolinic acid with various structures, which are compounds exhibiting a high extraction capacity for various metals.
ABSTRACT New polymeric electrochemical sensors for determining the content of lead were suggested... more ABSTRACT New polymeric electrochemical sensors for determining the content of lead were suggested. As the active substance of the polymeric membranes of the sensors was used N,N′-tetrabutyldipicolinamide, the compound exhibiting a high extractive capacity for heavy metal ions. The selectivity of the sensors with respect to lead ions in the presence of copper, cadmium, and zinc in a considerable excess was studied.
The main types of modern multisensor systems of the The main types of modern multisensor systems ... more The main types of modern multisensor systems of the The main types of modern multisensor systems of the electronic tongue type as well as the sensitive materials and sensors electronic tongue type as well as the sensitive materials and sensors (transducers) employed in such systems are considered. The most (transducers) employed in such systems are considered. The most commonly used analytical applications of the electronic tongue commonly used analytical applications of the electronic tongue including recognition and classification of various liquid media, including recognition and classification of various liquid media, quantitative analysis, process monitoring and taste assessment of quantitative analysis, process monitoring and taste assessment of foodstuffs are discussed. The bibliography includes 84 references foodstuffs are discussed. The bibliography includes 84 references. .
A variety of new chemical sensors for determination of triple charged rare earth (RE) metal catio... more A variety of new chemical sensors for determination of triple charged rare earth (RE) metal cations from lanthanum(III) to lutetium(III) (lanthanides) has been developed and studied. Well-known extractants-bidentate neutral organophosphorous compounds, such as methylene diphosphine dioxides and carbamoylmethylphosphine oxides and tetraoctyl-3-oxapentanediamide (TODGA) were used as neutral ligands in the polymeric sensor membranes. It was found that addition of certain substances that are called "anionic modifiers" in sensor terminology (tetrabistrifluoromethylphenyl-borate (TFPB), chlorinated cobalt dicarbollide (CCD)) often results in increase of sensor sensitivity to lanthanides. Different sensors based on the extractants exhibit remarkable sensitivity to RE metal cations and their selectivity (cross-sensitivity) can be widely governed by changing the composition of the membranes. Chemical sensors based on the extractants show good promise for analysis of RE mixtures in complex solutions containing various other components. The developed sensors can be particularly interesting for the analysis of highly radioactive liquid waste (HLW).
nanosheets as the biomimetic oxidase for rapid and sensitive oxalate detection combining with bio... more nanosheets as the biomimetic oxidase for rapid and sensitive oxalate detection combining with bionic E-eye, Biosensors and Bioelectronic,
Multisensor systems for liquid analysis based on chemical sensor arrays and pattern recognition, ... more Multisensor systems for liquid analysis based on chemical sensor arrays and pattern recognition, which are now widely known as 'electronic tongues', represent one of the most rapidly emerging and exciting fields of non-classical analytics during the last decade. This chapter presents an overview of the research and development of electronic tongue systems and describes various sensors, sensor arrays, and their numerous applications. A sound basis for electronic tongues was provided by the extensive development of well-known selective sensors, especially electrochemical, and biological inspirations originating from sensory systems of mammalians. The up-to-date achievements of various scientific groups working in this field are reviewed. The performance of electronic tongues in the tasks of recognition (classification, identification, discrimination) of multicomponent media is considered. A useful option of multicomponent quantitative analysis with the help of electronic tongues is also reported. The correlation between the output of an electronic tongue and human sensory assessments of food flavor made by taste panel opens up an exciting possibility of measuring and quantifying the taste and flavor of foods. Application areas of the electronic tongue systems, including quality control of foodstuffs, clinical, industrial and environmental analysis, are surveyed. Future prospects for research and development of electronic tongues are discussed.
An electronic tongue based on the transient response of an array of non-specific-response potenti... more An electronic tongue based on the transient response of an array of non-specific-response potentiometric sensors was developed. A sequential injection analysis (SIA) system was used in order to automate its training and operation. The use of the transient recording entails the dynamic nature of the sensor's response, which can be of high information content, of primary ions and also of interfering ions; these may better discriminated if the kinetic resolution is added. This work presents the extraction of significant information contained in the transient response of a sensor array formed by five all-solid-state potentiometric sensors. The tool employed was the Fourier transform, from which a number of coefficients were fed into an artificial neural network (ANN) model, used to perform a quantitative multidetermination. The studied case was the analysis of mixtures of calcium, sodium and potassium. Obtained performance is compared with the more traditional automated electronic tongue using final steady-state potentials.
The potential of multisensor array in continuous on-line monitoring of processed water quality at... more The potential of multisensor array in continuous on-line monitoring of processed water quality at aeration plant is explored. The responses of 23 potentiometric sensors were continuously registered every seven seconds through the 26 days of experiment in a special container having connection with outlet water line of the aeration plant. Using chemometric tools it is shown that potentiometric "electronic tongue" is capable of evaluation of two important parameters of water quality: ammonium nitrogen and nitrate nitrogen. Unlike traditional sampling-based analysis the results of multisensor are available immediately in a real-time mode. Moreover, the achieved precision is sufficient to monitor possible alarm events. The employment of topological data analysis allowed for exploration of the very large dataset (295,828 measurements) accumulated through the long period of continuous measurements with sensors and for judgment on stability of water quality.
The electronic tongue (ET) multisensor system has been employed for the detection of metal-oxygen... more The electronic tongue (ET) multisensor system has been employed for the detection of metal-oxygen cluster anions (polyoxometalates) containing vanadium (IV/V) atoms. Sensitivity of a variety of potentiometric chemical sensors with plasticized polyvinyl chloride and chalcogenide glass membranes was evaluated with respect to vanadyl/vanadate ions, decavanadate and a series of Keggin-type polyoxometalates (POM) such as ␣-[SiW 11 V IV O 40 ] 6− , ␣-[SiW 11 V V O 40 ] 5− , ␣-[BW 11 V IV O 40 ] 7− , ␣-[BW 11 V V O 40 ] 6− , ␣-[PW 11 V IV O 40 ] 5− and ␣-[PW 12−n V n V O 40 ] (3+n)− (n = 1, 2, 3). Sensor's responses to vanadium complexes were evaluated in the pH range of 2.4-6.5 and a set of sensors appropriate for detecting a variety of vanadium species was selected. Such sensor array was able to distinguish different vanadium complexes allowing their simultaneous quantification in binary (V(IV)/V(V)) mixtures. The vanillyl alcohol oxidation with ␣-[SiW 11 V V O 40 ] 5− was monitored using ET to evaluate the capacity of proposed analytic system to detect simultaneously V(IV)/V(V) in POM under dynamic equilibrium. ET was demonstrated to be a promising tool for the discrimination and quantification of vanadium-containing POMs at different oxidation states. In particular, such a system could represent a significant interest for the mechanistic studies of redox reactions with POMs.
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