Electronic Tongue Coupled to an Electrochemical Flow Reactor for Emerging Organic Contaminants Real Time Monitoring

Triclosan, which is a bacteriostatic used in household items, has raised health concerns, because it might lead to antimicrobial resistance and endocrine disorders in organisms. The detection, identification, and monitoring of triclosan and its by-products (methyl triclosan, 2,4-Dichlorophenol and 2,4,6-Trichlorophenol) are a growing need in order to update current water treatments and enable the continuous supervision of the contamination plume. This work presents a customized electronic tongue prototype coupled to an electrochemical flow reactor, which aims to access the monitoring of triclosan and its derivative by-products in a real secondary effluent. An electronic tongue device, based on impedance measurements and polyethylenimine/poly(sodium 4-styrenesulfonate) layer-by-layer and TiO2, ZnO and TiO2/ZnO sputtering thin films, was developed and tested to track analyte degradation and allow for analyte detection and semi-quantification. A degradation pathway trend was observable by means of principal component analysis, being the sample separation, according to sampling time, explained by 77% the total variance in the first two components. A semi-quantitative electronic tongue was attained for triclosan and methyl-triclosan. For 2,4-Dichlorophenol and 2,4,6-Trichlorophenol, the best results were achieved with only a single sensor. Finally, working as multi-analyte quantification devices, the electronic tongues could provide information regarding the degradation kinetic and concentrations ranges in a dynamic removal treatment.

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Discrimination of Milks with a Multisensor System Based on Layer-by-Layer Films

Sensors ◽

10.3390/s18082716 ◽

2018 ◽

Vol 18 (8) ◽

pp. 2716 ◽

Cited By ~ 8

Author(s):

Coral Salvo-Comino ◽

Celia García-Hernández ◽

Cristina García-Cabezón ◽

Maria Rodríguez-Méndez

Keyword(s):

Copper Phthalocyanine ◽

Electronic Tongue ◽

Principal Component ◽

Sensor System ◽

Galactose Oxidase ◽

Milk Analysis ◽

Layer By Layer ◽

Additional Information ◽

Milk Samples ◽

Calibration Models

A nanostructured electrochemical bi-sensor system for the analysis of milks has been developed using the layer-by-layer technique. The non-enzymatic sensor [CHI+IL/CuPcS]2, is a layered material containing a negative film of the anionic sulfonated copper phthalocyanine (CuPcS) acting as electrocatalytic material, and a cationic layer containing a mixture of an ionic liquid (IL) (1-butyl-3-methylimidazolium tetrafluoroborate) that enhances the conductivity, and chitosan (CHI), that facilitates the enzyme immobilization. The biosensor ([CHI+IL/CuPcS]2-GAO) results from the immobilization of galactose oxidase on the top of the LbL layers. FTIR, UV–vis, and AFM have confirmed the proposed structure and cyclic voltammetry has demonstrated the amplification caused by the combination of materials in the film. Sensors have been combined to form an electronic tongue for milk analysis. Principal component analysis has revealed the ability of the sensor system to discriminate between milk samples with different lactose content. Using a PLS-1 calibration models, correlations have been found between the voltammetric signals and chemical parameters measured by classical methods. PLS-1 models provide excellent correlations with lactose content. Additional information about other components, such as fats, proteins, and acidity, can also be obtained. The method developed is simple, and the short response time permits its use in assaying milk samples online.

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Use of an electronic tongue in the assessment of highly diluted systems

International Journal of High Dilution Research - ISSN 1982-6206 ◽

10.51910/ijhdr.v10i36.485 ◽

2021 ◽

Vol 10 (36) ◽

pp. 104-107

Author(s):

Mateus Silva Laranjeira ◽

Marilisa GuimarÃƒÆ’Ã‚Â£es Lara ◽

Marco Vinicius Chaud ◽

Olney Leite Fontes ◽

AntÃƒÆ’Ã‚Â´nio Riul Jr

Keyword(s):

Ultrathin Films ◽

Electronic Tongue ◽

Principal Component ◽

Original Data ◽

Relevant Information ◽

Statistical Correlation ◽

Layer By Layer ◽

Layer Technique ◽

Liquid Systems ◽

Complex Liquid

Introduction: ÃƒÂ¢Ã¢â€šÂ¬Ã…â€œEletronic tongueÃƒÂ¢Ã¢â€šÂ¬Ã‚Â is a device commonly used in the analysis of tastants, heavy metal ions, fruit juice, wines and also in the development of biosensors [1-3]. Briefly, the e-tongue is constituted by sensing units formed by ultrathin films of distinct materials deposited on gold interdigitated electrodes, which are immersed in liquid samples, followed by impedance spectroscopy measurements [1]. The e-tongue sensor is based on the global selectivity concept, i.e., the materials forming the sensing units are not selective to any substance in the samples, therefore, it allows the grouping of information into distinct patterns of response, enabling the distinction of complex liquid systems [1]. Aim: Our aim was to use e-tongue system for the assessment the homeopathic medicine Belladonna at different degrees of dilution, in attempt to differentiate highly diluted systems. Methods: Ultrathin films forming the sensing units were prepared by the layer-by-layer technique [4], using conventional polyelectrolytes such as poly(sodium styene sulfonate) (PSS) and poly(allylamine) hydrochloride (PAH), chitosan and poly(3,4-ethylenedioxythiophene) (PEDOT). Homeopathic medicines (Belladonna 1cH, 6cH, 12cH and 30cH) were prepared by dilution and agitation according to HahnemannÃƒâ€šÃ‚Â´s method [5], using ethanol at 30% (w/w) as vehicle. Experimental data acquisition was conducted by blind tests measurements involving Belladonna samples and the vehicle used in the dilutions. Five independent and consecutive measurements were taken for each solution at 1 kHz, which were further analysed by Principal Component Analysis (PCA), a statistical method largely employed to reduce the dimensionality of the original data without losing information in the correlation of the samples [3]. Results: Figure 1 shows that the five independent measurements are grouped quite closed each other for each solution analysed, with a clear distinction of them. Therefore, it was noticed a change in the observed pattern measured at different days, indicating a reduced reproducibility, although the groups of data could still be identified. Discussion: PCA is a powerful tool highly employed to extract relevant information in the correlation of data analysis of e-tongue systems. PCA plots showed a good statistical correlation of the systems (PC1 + PC2 Ãƒâ€šÃ‚Â³ 90%), with the solutions being straightforwardly distinguished each other and also from the vehicle used. Conclusion: Despite the differences of data obtained along distinct days of analysis, the e-tongue could detect differences among the samples tested, even considering the highly diluted cases studied.

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Polyelectrolyte Based Sensors as Key to Achieve Quantitative Electronic Tongues: Detection of Triclosan on Aqueous Environmental Matrices

Nanomaterials ◽

10.3390/nano10040640 ◽

2020 ◽

Vol 10 (4) ◽

pp. 640

Author(s):

Cátia Magro ◽

Paulo Zagalo ◽

João Pereira-da-Silva ◽

Eduardo Pires Mateus ◽

Alexandra Branco Ribeiro ◽

...

Keyword(s):

Continuous Monitoring ◽

Mineral Water ◽

Electronic Tongue ◽

Principal Component ◽

Electrical Impedance Spectroscopy ◽

Layer By Layer ◽

Environmental Matrices ◽

Film Stability ◽

Lbl Films ◽

Water And Wastewater

Triclosan (TCS) is a bacteriostatic used in household items that promotes antimicrobial resistance and endocrine disruption effects both to humans and biota, raising health concerns. In this sense, new devices for its continuous monitoring in complex matrices are needed. In this work, sensors, based on polyelectrolyte layer-by-layer (LbL) films prepared onto gold interdigitated electrodes (IDE), were studied. An electronic tongue array, composed of (polyethyleneimine (PEI)/polysodium 4-styrenesulfonate (PSS))5 and (poly(allylamine hydrochloride/graphene oxide)5 LbL films together with gold IDE without coating were used to detect TCS concentrations (10−15–10−5 M). Electrical impedance spectroscopy was used as means of transduction and the obtained data was analyzed by principal component analysis (PCA). The electronic tongue was tested in deionized water, mineral water and wastewater matrices showing its ability to (1) distinguish between TCS doped and non-doped solutions and (2) sort out the TCS range of concentrations. Regarding film stability, strong polyelectrolytes, as (PEI/PSS)n, presented more firmness and no significant desorption when immersed in wastewater. Finally, the PCA data of gold IDE and (PEI/PSS)5 sensors, for the mineral water and wastewater matrices, respectively, showed the ability to distinguish both matrices. A sensitivity value of 0.19 ± 0.02 per decade to TCS concentration and a resolution of 0.13 pM were found through the PCA second principal component.

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Electronic Tongue Based on Nanostructured Hybrid Films of Gold Nanoparticles and Phthalocyanines for Milk Analysis

Journal of Nanomaterials ◽

10.1155/2015/890637 ◽

2015 ◽

Vol 2015 ◽

pp. 1-7 ◽

Cited By ~ 14

Author(s):

Luiza A. Mercante ◽

Vanessa P. Scagion ◽

Adriana Pavinatto ◽

Rafaela C. Sanfelice ◽

Luiz H. C. Mattoso ◽

...

Keyword(s):

Gold Nanoparticles ◽

Chemical Sensors ◽

Film Growth ◽

Electronic Tongue ◽

Principal Component ◽

Inorganic Materials ◽

Milk Analysis ◽

Layer By Layer ◽

Nanostructured Films ◽

Lbl Films

The use of gold nanoparticles combined with other organic and inorganic materials for designing nanostructured films has demonstrated their versatility for various applications, including optoelectronic devices and chemical sensors. In this study, we reported the synthesis and characterization of gold nanoparticles stabilized with poly(allylamine hydrochloride) (Au@PAH NPs), as well as the capability of this material to form multilayer Layer-by-Layer (LbL) nanostructured films with metal tetrasulfonated phthalocyanines (MTsPc). Film growth was monitored by UV-Vis absorption spectroscopy, atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). Once LbL films have been applied as active layers in chemical sensors, Au@PAH/MTsPc and PAH/MTsPc LbL films were used in an electronic tongue system for milk analysis regarding fat content. The capacitance data were treated using Principal Component Analysis (PCA), revealing the role played by the gold nanoparticles on the LbL films electrical properties, enabling this kind of system to be used for analyzing complex matrices such as milk without any prior pretreatment.

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Multisensor System Based on Layer by Layer Films. Discrimination of Milks

10.20944/preprints201807.0491.v1 ◽

2018 ◽

Author(s):

Coral Salvo-Comino ◽

Celia Garcia-Hernandez ◽

Cristina Garcia-Cabezon ◽

Maria Luz Rodriguez-Mendez

Keyword(s):

Copper Phthalocyanine ◽

Electronic Tongue ◽

Principal Component ◽

Sensor System ◽

Galactose Oxidase ◽

Milk Analysis ◽

Layer By Layer ◽

Additional Information ◽

Milk Samples ◽

On Line

A nanostructured electrochemical bi-sensor system for analysis of milks has been developed using the Layer by Layer technique. The non-enzymatic sensor [CHI+IL/CuPcS]2, is a layered material containing a negative film of the anionic sulfonated copper phthalocyanine (CuPcS) acting as electrocatalytic material, and a cationic layer containing a mixture of an ionic liquid (IL) (1-butyl-3-methylimidazolium tetrafluoroborate) that enhances the conductivity and chitosan (CHI) that facilitates the enzyme immobilization. The biosensor ([CHI+IL/CuPcS]2-GAO) results from the immobilization of galactose oxidase on the top of the LbL layers. FTIR, UV-vis and AFM have confirmed the proposed structure and cyclic voltammetry has demonstrated the amplification caused by the combination of materials in the film. Sensors have been combined to form an electronic tongue for milk analysis. Principal Component Analysis has revealed the ability of the sensor system to discriminate between milk samples with different lactose content. Using PLS-1 calibration models, correlations have been found between the voltammetric signals and chemical parameters measured by classical methods. PLS-1 models provide excellent correlations with lactose content. Additional information about other components such as fats, proteins and acidity can also be obtained. The method developed is simple and the short response time permits its use in assaying milk samples on-line.

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Evaluation of fluorescence excitation–emission and LC-OCD as methods of detecting removal of NOM and DBP precursors by enhanced coagulation

Water Science & Technology Water Supply ◽

10.2166/ws.2011.101 ◽

2011 ◽

Vol 11 (5) ◽

pp. 621-630 ◽

Cited By ~ 17

Author(s):

J. K. Wassink ◽

R. C. Andrews ◽

R. H. Peiris ◽

R. L. Legge

Keyword(s):

Natural Organic Matter ◽

Principal Component ◽

Close Correlation ◽

Quantitative Detection ◽

Aluminium Sulphate ◽

Fluorescence Excitation ◽

Enhanced Coagulation ◽

Carbon Detection ◽

Linear Correlations ◽

By Products

Bench-scale tests were conducted to evaluate enhanced coagulation as a method for removing natural organic matter (NOM) from a surface water to reduce the formation of disinfection by-products (DBPs). Aluminium sulphate (alum) and two polyaluminium chloride (PACl) coagulants were used, as well as alum with pH depression. Using a PACl coagulant alone or alum with pH depression was shown to attain 35% removal of TOC at lower dosages (31 and 29 mg/L, respectively) when compared to the use of alum alone (43 mg/L). In addition to TOC and UV254, a fluorescence excitation–emission matrix (FEEM) approach and liquid chromatography–organic carbon detection (LC-OCD) were used to further characterize the removal of NOM in both untreated and filtered waters. Principal component analysis of FEEM was able to identify the presence of humic-like substances (HS), protein-like substances (PS), and colloidal/particulate matter (CPM); HS were found to have a close correlation with TOC and UV254. LC-OCD enabled the quantitative detection of hydrophobic and hydrophilic DOC; the latter was further separated into five components, the largest of which was HS. Strong linear correlations were calculated between TOC, UV254, HS, and hydrophilic DOC (r2 > 0.96); these parameters were also found to be closely correlated with the formation of trihalomethanes (THMs, r2 > 0.78) and haloacetic acids (HAAs, r2 > 0.92). Linear correlations with THMs and HAAs indicated that FEEM and LC-OCD provide good measures of DBP precursors when compared with TOC and UV254.

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Magnetron Sputtering Thin Films as Tool to Detect Triclosan in Infant Formula Powder: Electronic Tongue Approach

Coatings ◽

10.3390/coatings11030336 ◽

2021 ◽

Vol 11 (3) ◽

pp. 336

Author(s):

Cátia Magro ◽

Margarida Sardinha ◽

Paulo A. Ribeiro ◽

Maria Raposo ◽

Susana Sério

Keyword(s):

Thin Films ◽

Infant Formula ◽

Tap Water ◽

Milk Powder ◽

Electronic Tongue ◽

Principal Component ◽

Formula Milk ◽

Straight Line ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

Triclosan (TCS) is being detected in breast milk and in infants of puerperal women. The harmful effects caused by this compound on living beings are now critical and thus it is pivotal find new tools to TCS monitoring. In the present study, an electronic tongue (e-tongue) device comprising an array of sputtered thin films based on Multi-Walled Carbon Nanotubes and titanium dioxide was developed to identify TCS concentrations, from 10−15 to 10−5 M, in both water and milk-based solutions. Impedance spectroscopy was used for device signal transducing and data was analyzed by principal component analysis (PCA). The e-tongue revealed to be able to distinguish water from milk-based matrices through the two Principal Components (PC1 and PC2), which represented 67.3% of the total variance. The PC1 values of infant formula milk powder prepared with tap water (MT) or mineral water (MMW) follows a similar exponential decay curve when plotted with the logarithm of concentration. Therefore, considering the TCS concentration range between 1015 and 10−9 M, the PC1 values are fitted by a straight line and values of −1.9 ± 0.2 and of 7.6 × 10−16 M were calculated for the sensor sensitivity and sensor resolution, respectively. Additionally, a strong correlation (R = 0.96) between MT and MMW PC1 data was found. These results have shown that the proposed device corresponds to a promisor method for the detection of TCS in milk-based solutions.

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Characterization and Source of Trihalomethane Formation in the Secondary Effluent by Sequencing Batch Reactors

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.316-317.323 ◽

2013 ◽

Vol 316-317 ◽

pp. 323-326

Author(s):

Chao Jie Zhang ◽

Si Bo Li ◽

Qian Chen ◽

Qi Zhou

Keyword(s):

Organic Matter ◽

Activated Carbon ◽

Dissolved Organic Matter ◽

Secondary Effluent ◽

Batch Reactors ◽

Sequencing Batch Reactors ◽

Human Beings ◽

By Products

Dissolved organic matter (DOM) may do harms to human beings. After disinfected by chlorine (amine), DOM can form disinfection by-products (DBPs) which can be mutagenic, teratogenic and carcinogenic. Characterization and source of trihalomethane precursors in the secondary effluent by sequencing batch reactors were investigated. CHCl3 was the primary DBPs. The results showed that the precursors of CHCl3 were mainly strongly hydrophobic DOM, while CHCl2Br and CHClBr2 were mainly formed from hydrophilic DOM. The effects of different powder media (activated carbon, zeolite) on removal of DOM were compared. The results showed that the dosing of powder media can promote the removal of DOM and the DBPs precursors.

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Identification of Umami Taste in Sous-Vide Beef by Chemical Analyses, Equivalent Umami Concentration, and Electronic Tongue System

Foods ◽

10.3390/foods9030251 ◽

2020 ◽

Vol 9 (3) ◽

pp. 251 ◽

Cited By ~ 1

Author(s):

Young-Hwa Hwang ◽

Ishamri Ismail ◽

Seon-Tea Joo

Keyword(s):

Amino Acids ◽

Principal Component Analysis ◽

Food Processing ◽

Free Amino Acids ◽

Free Amino ◽

Electronic Tongue ◽

Principal Component ◽

Chemical Analyses ◽

Umami Taste ◽

Sous Vide

Behaviour of umami compounds that are associated with non-volatile compounds on slow cooking regimes remains less explored. This study aims to assess the ability of the electronic tongue system on the umami taste from sous-vide beef semitendinosus. The identification was based on the taste-enhancing synergism between umami compounds 5’-nucleotides (IMP, GMP, AMP, inosine, and hypoxanthine) and free amino acids (glutamic and aspartic acid) using the estimation of equivalent umami concentration (EUC) and electronic tongue system. Sous-vide cooked at 60 and 70 °C for 6 and 12 h and cooked using the conventional method at 70 °C for 30 min (as control) were compared. The temperature had a significant effect on 5’-nucleotides, but aspartic and glutamic acid were not influenced by any treatments applied. Sous-vide cooked at 60 °C tended to have higher inosine and hypoxanthine. Meanwhile, desirable 5’-nucleotides IMP, AMP, and GMP were more intensified at the temperature of 70 °C. The principal component analysis predicted a good correlation between EUC and the electronic tongue, with sous-vide at 70 °C for 12 h presenting the most umami. Therefore, the electronic tongue system is a useful tool in food processing, particularly in determining complex sensory properties such as umami, which cannot be evaluated objectively.

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Wine Authentication Using Integration Assay of MIR, NIR, E-tongue, HS-SPME-GC-MS, and Multivariate Analyses: A Case Study for a Typical Cabernet Sauvignon Wine

Journal of AOAC International ◽

10.5740/jaoacint.18-0327 ◽

2019 ◽

Vol 102 (4) ◽

pp. 1174-1180

Author(s):

Xinyu Jin ◽

Shimin Wu ◽

Wenjuan Yu ◽

Xinyi Xu ◽

Mingquan Huang ◽

...

Keyword(s):

Near Infrared ◽

Solid Phase ◽

Electronic Tongue ◽

Nir Spectroscopy ◽

Principal Component ◽

Hierarchical Cluster ◽

Cabernet Sauvignon ◽

Mir Spectroscopy ◽

Wine Authentication ◽

Grey Relational

Abstract Background: Cabernet Sauvignon wine enjoys large market in China, and its adulteration has become a well-known problem and challenge. Objective: This study aims to evaluate the capabilities of multiple techniques, including headspace–solid-phase microextraction–GC-MS (HS-SPME-GC-MS), electronic tongue (E-tongue) spectroscopy, mid-infrared (MIR) spectroscopy, and near-infrared (NIR) spectroscopy, to differentiate this popular imported wine in China. Methods: MIR spectroscopy, NIR spectroscopy, E-tongue spectroscopy, and HS-SPME-GC-MS were used. Multivariate analysis techniques were applied to further explore the instrumental determination data for the wine discrimination. Results: Joint use of MIR and NIR with Grey relational analysis (GRA), E-tongue with principal component analysis (PCA) and hierarchical cluster analysis, and HS-SPME-GC-MS with PCA allowed unanimous differentiation of the wines. Conclusions: The approach described herein offers both ecologically friendly and multiperspective mutual corroboration techniques for Cabernet Sauvignon wine discrimination. The integrative methodology could be used as a reference for wine authentication. Highlights: GRA was first applied to discriminate the wine samples. Mutual corroboration was verified by multivariate statistics combined with MIR, NIR, E-tongue, and SPME-GC/MS. Integrated techniques pointed to a unanimous authentication of the wine samples.

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