Larisa Lvova

Evaluation of Italian wine by the electronic tongue: recognition, quantitative analysis and correlation with human sensory perception

Abstract The electronic tongue based on a sensor array comprising 23 potentiometric cross-sensitive chemical sensors and pattern recognition and multivariate calibration data processing tools was applied to the analysis of Italian red wines. The measurements were made in 20 samples of Barbera d’Asti and in 36 samples of Gutturnio wine. The electronic tongue distinguished all wine samples of the same denomination and vintage, but from different vineyards. Simultaneously the following quantitative parameters of the wines were measured by the electronic tongue with precision within 12%: total and volatile acidity, pH, ethanol content, contents of tartaric acid, sulphur dioxide, total polyphenols, glycerol, etc. The electronic tongue is sensitive to multiple substances that determine taste and flavour of wine and, hence, the system was capable of predicting human sensory scores with average precision of 13% for Barbera d’Asti wines and 8% for Gutturnio wines.

Electronic nose and electronic tongue integration for improved classification of clinical and food samples

Abstract A combined approach based on a multisensor system, to get chemical information from liquid samples through the analysis of the solution and its head space is illustrated and commented. Sensors operating in liquid (electronic tongue) and in the head space (electronic nose) are based on the same sensitive materials: the metalloporphyrins. This gives the opportunity of a certain uniformity of interaction putting in evidence the differences between the solution and its related volatile part. The combined system has been tested in two different experiments in the fields of clinical and food analysis, respectively. Results have shown a net increase of information when the combined systems are used. The sensor fusion procedure has been optimised in order to achieve the best results.

Multicomponent analysis of Korean green tea by means of disposable all-solid-state potentiometric electronic tongue microsystem

Abstract All-solid-state ‘electronic tongue’ microsystem comprised of polymeric sensors of different types such as highly cross-sensitive sensors based both on PVC and aromatic polyurethane (ArPU) matrices doped with various membrane active components, electrochemically deposited conductive films of polypyrrole (PPy) and polyaniline (PAn) and potentiometric glucose biosensors has been developed and applied for the analysis of beverages: natural coffee, black tea and different sorts of green teas. The system can discriminate different kinds of teas (black and green) and natural coffees. Components that are responsible for giving unique taste such as caffeine, catechines, sugar, amino acid l -arginine have been determined for green tea samples with unknown manufacturer specifications.

Application of a combined artificial olfaction and taste system to the quantification of relevant compounds in red wine

Abstract The combined application of an electronic nose and an electronic tongue to a number of samples of red wine having the same denomination, produced in the same year but from different vineyards, is illustrated and discussed. Artificial sense data have been compared with the analytical chemistry analysis performed with ordinary methods. The data reveal, first of all, a net distinction between electronic nose and electronic tongue, confirming the hypotheses that both the systems offer independent information on the samples. A certain correlation with some of the analytical indicators has also been found and a neural network regression model has been assessed for the qualitative determination of some of them.

Chemical sensor array for multicomponent analysis of biological liquids

Abstract The development of new methods of on-line monitoring of biological liquids such as human blood, blood plasma or dialysis solutions for artificial kidney is still an urgent task. Ion-selective chemical sensors (ISEs) are convenient instruments for this purpose and are widely used in commercial blood analysers. However, they have significant drawbacks. The promising way to overcome them is the use of array of sensors with cross-sensitivity together with pattern recognition methods. The present work has been concerned with the development of a multisensor system for simultaneous determination of Ca 2+ , Mg 2+ , Na + , HCO − 3 , Cl − , H + and HPO 2− 4 ions in solution modelling human blood plasma. The sensor array included 30 sensors based on non-specific original PVC materials, both cation- and anion-sensitive. Sensing materials for the array were chosen on the basis of cross-sensitivity estimation results with the help of the method that we suggested earlier. Back-propagation artificial neural network was utilised for data processing. It was demonstrated that the sensor array approach allows to measure the content of all these species with an average precision of about 1–4% depending on the component in typical ranges for biological liquids, including Mg 2+ , HCO − 3 and H 2 PO − 4 determination and pH measurement without an oxide glass pH-electrode.

Multimodal use of new coumarin-based fluorescent chemosensors: Towards highly selective optical sensors for Hg2+ probing

Despite several types of fluorescent sensing molecules have been proposed and examined to signal Hg(2+) ion binding, the development of fluorescence-based devices for in-field Hg(2+) detection and screening in environmental and industrial samples is still a challenging task. Herein, we report the synthesis and characterization of three new coumarin-based fluorescent chemosensors featuring mixed thia/aza macrocyclic framework as receptors units, that is, ligands L1-L3. These probes revealed an OFF-ON selective response to the presence of Hg(2+) ions in MeCN/H2 O 4:1 (v/v), which allowed imaging of this metal ion in Cos-7 cells in vitro. Once included in silica core-polyethylene glycol (PEG) shell nanoparticles or supported on polyvinyl chloride (PVC)-based polymeric membranes, ligands L1-L3 can also selectively sense Hg(2+) ions in pure water. In particular we have developed an optical sensing array tacking advantage of the fluorescent properties of ligand L3 and based on the computer screen photo assisted technique (CSPT). In the device ligand L3 is dispersed into PVC membranes and it quantitatively responds to Hg(2+) ions in natural water samples.

Electronic tongue based on an array of metallic potentiometric sensors

An electronic tongue system based on the array of six metallic potentiometric sensors (metallic wires) was developed and utilized for discrimination of foodstuffs: several types of vinegar and fruit juices. Copper, tin, iron, aluminum, brass and stainless steel wires were included in the array and supplemented by pH glass electrode. The response of potentiometric metallic sensors towards various organic acids has been studied and possible sensitivity mechanisms were discussed. Overall potential changes of metallic sensors were exanimate as complex mixed signals influenced by several components presenting in analyte employing chemometric approach. The multisensor array of such a type can be useful for several applications since of simplicity in handling, low cost of sensors and easy measure procedure.

Clinical analysis of human urine by means of potentiometric Electronic tongue.

The Electronic tongue (ET) composed of different kind of potentiometric chemical sensors has been applied for the detection of urinary system dysfunctions and creatinine levels. The creatinine contents evaluated by ET were compared with those obtained by automated Jaffes method and GC-MS, obtaining a satisfying agreement for both methods. Partial least square regression discriminate analysis (PLS-DA) and feed forward back-propagation neural network (FFBP NN) classified 51 urine specimens from healthy volunteers in four classes, according to the creatinine content, showing that both techniques can satisfactorily differentiate urines according to this parameter. The best accuracy result of 92.2% correct classification of unknown samples was achieved with FFBP NN. Moreover, the possibility of ET system to distinguish between urine samples of healthy patients, and those with malignant and non-malignant tumor diagnosis of bladder has been shown.

Metalloporphyrin-Based Electronic Tongue: an Application for the Analysis of Italian White Wines

An Electronic Tongue system (ET) composed of “all-solid-state” potentiometric sensors was developed and applied for the identification of white wines. The sensing properties were due to the PVC based membranes doped with several metallo-porphyrins deposited on the surface of glassy carbon working electrodes; potentiometric response towards several ions in a concentration range from 10-5M to 10-1M were studied and cross-sensitivity of sensors was estimated. The sensor array was applied both for the classification and quantitative analysis of “Verdicchio D.O.C.” Italian dry white wines produced by nine cantinas. Peculiar parameters of white wines (namely alcoholic degree, volatile acidity, SO2, L-Malic Acid, L-Lactic Acid and Total Polyphenols) individuated by standard analytical methods were compared with the values evaluated by metalloporphyrin-based ET. The system satisfactory discriminates between an artificial wine control and analyzed wines coming from different cantinas and produced in different years. A satisfactory correlation between results of wine analysis performed by certified methods and ET response has been obtained for SO2, L-Malic Acid, and Total Phenols content. The developed procedure allows the monitoring of the acetic acid amount in wines and hence to control wine volatile acidity, so indicating the initial steps of wine spoilage process.

A Ferrocene-Porphyrin Ligand for Multi-Transduction Chemical Sensor Development

5,10,15,20-Tetraferrocenyl porphyrin, H2TFcP, a simple example of a donor-acceptor system, was tested as ligand for the development of a novel multi-transduction chemical sensors aimed at the determination of transition metal ions. The fluorescence energy transfer between ferrocene donor and porphyrin acceptor sub-units was considered. The simultaneously measured optical and potentiometric responses of solvent polymeric membranes based on H2TFcP permitted the detection of lead ions in sample solutions, in the concentration range from 2.7 × 10−7 to 3.0 × 10−3 M. The detection limit of lead determination was 0.27 μM, low enough to perform the direct analysis of Pb2+ in natural waters.