Search

Chalcogenide glass electrode was applied to the detection of mercury(II) activity in the saline bromide buffers and artificial seawater at the activity levels corresponding to the acute toxicity. Mercury(II) toxicity in artificial seawater buffers and estuarine water was assessed using bioassay based on the luminescence of the marine bacterium A. fischeri. Electrode could detect mercury activity in the artificial seawater at the level of acute toxicity, which corresponded to pHg 23.2 (time of exposure 5 min.). Both electrode and bioassay indicated higher Hg2+ activity/toxicity in the estuarine water collected in the contaminated area. Quantification of Hg2+ activity in estuarine water using the mercury-selective electrode requires calibration procedure to account for matrix effects.

Modified eucalyptus kraft lignin doped with multiwall carbon nanotubes (MWCNTs) was used as a macromonomer in step-growth polymerization with tolylene 2,4-diisocyanate terminated poly(propylene glycol) with the aim of producing a conductive copolymer for all-solid-state potentiometric chemical sensor applications. The crosslinked elastomeric polyurethane obtained was characterized by Fourier transform infrared attenuated total reflection spectroscopy, scanning electron microscopy, tunnelling electron microscopy and atomic force microscopy. Doping of lignin-based polyurethane with MWCNTs produced a significant enhancement of its electrical conductivity without deterioration of thermal and viscoelastic properties. The polymer composite displayed a low percolation threshold at an MWCNT concentration of 0.18% (w/w), which was explained by the oriented distribution of MWCNTs along lignin clusters. All lignin-based polyurethanes doped with MWCNTs at concentrations above the percolation threshold are suitable for sensor applications. Copyright © 2012 Society of Chemical Industry

An electronic tongue comprising thirty potentiometric chemical sensors and pattern recognition tools for data processing was used for the analysis of mineral waters, coffee, soft drinks and flesh food, namely fish. The electronic tongue appeared to be capable of distinguishing between different sorts of beverages: natural and artificial mineral waters, individual and commercial brands of coffee, and commercial and experimental samples of soft drinks containing different sweeteners. A quantitative correlation between human perception and `electronic tongue' output was obtained. Taste parameter assessments produced by a professional taste panel was used for `electronic tongue' calibration. It was found that the `electronic tongue' is capable of distinguishing sea water and freshwater fish and monitoring their spoilage.

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 comprising 29 potentiometric chemical sensors and pattern recognition tools for the data processing has been applied for the analysis of Italian produced mineral waters and dry red wines. The electronic tongue appeared to be capable to distinguish between different sorts of mineral waters, between contaminated by organic matter waters and pure ones and between Barbera wine samples of the same denomination but from different vineyards. Simultaneously with qualitative recognition, quantitative determination of some components in the water and the wine has been performed. The electronic tongue can be highly valuable in food quality control.

The main types of modern multisensor systems of the electronic tongue type as well as the sensitive materials and sensors (transducers) employed in such systems are considered. The most commonly used analytical applications of the electronic tongue including recognition and classification of various liquid media, quantitative analysis, process monitoring and taste assessment of foodstuffs are discussed.