Preparación, caracterización y aplicación de sensores de Pd-SnO como nariz electrónica en la clasificación de vinos peruanos y su comparación con técnicas cromatográficas / Preparation, characterization, and application of Pd-SnO sensors as an electronic nose in Peruvian wine classification and its comparison with chromatographic techniques / Preparação, caracterização e aplicação de sensores de Pd-SnO como nariz eletrônico na classificação dos vinhos peruanos e sua comparação com técnicas cromatográficas

Resumen Se prepararon sensores basados en SnO dopados con paladio (0, 1, 3, 5 y 7%) mediante el método de impregnación húmeda. Para caracterizarlos, se usaron las técnicas de espectroscopia infrarroja con transformada de Fourier (FTIR), adsorción y desorción de N2 (BET), difracción de rayos X (XRD), microscopía electrónica de barrido (SEM) y espectroscopia de energía dispersiva de rayos X (EDX). Los sensores se evaluaron con etanol para que conformaran, junto a dos sensores comerciales, una nariz electrónica (E-nose) que lograse detectar componentes volátiles del aroma en vinos peruanos. Los resultados fueron interpretados a través del análisis de componentes principales (PCA) con la finalidad de buscar una técnica que complementase la información recolectada por la cromatografía de gases (GC) y la cromatografía líquida (HPLC), y justamente comparando los PCAs obtenidos del GC y el HPLC con los resultantes de la E-nose se encontró que estos últimos clasificaban mejor las muestras. Fue posible diferenciar tanto vinos de la misma uva como de distinta cepa. Además, se logró detectar vinos adulterados, lo cual contribuye a la industria vitivinícola en el control de su producción con la finalidad de mejorar la calidad de esta bebida para el consumidor.

Abstract SnO-based sensors doped with palladium (0, 1, 3, 5 and 7%) were prepared by the wet impregnation method. To characterize them, the techniques ofinfrared spectroscopy with Fourier transform (FTIR), adsorption and desorption of N2 (BET), XRD, scanning electron microscopy (SEM), and X-ray dispersive energy (EDX) spectroscopy were used. The sensors were evaluated with ethanol to form, together with two commercial sensors, an electronic nose (E-nose) that could detect volatile aroma components in Peruvian wines. The results were interpreted through principal component analysis (PCA) to find a technique that complemented the information collected by gas chromatography (GC) and liquid chromatography (HPLC), and by comparing the PCAs obtained from GC, and HPLC with those resulting from E-nose. It was found that the latter classified the samples better. It was possible to differentiate both wines from the same grape and from a different strain, and to detect adulterated wines, which contributes to the wine industry in controlling its production to improve the quality of this drink for the consumer.

Resumo Os sensores baseados em SnO dopados com paládio (0, 1, 3, 5 e 7%) foram preparados pelo método de impregnação por via húmida. Para caracterizá-los, as técnicas de espectroscopia infravermelha com transformação de Fourier (FTIR), adsorção e dessorção de N2 (BET), XRD, microscopia eletrônica de varredura SEM) e espectroscopia de energia dispersiva de raios-X (EDX). Os sensores foram avaliados com etanol para formar, junto com dois sensores comerciais, um nariz eletrônico (E-nose) que poderia detectar componentes de aroma volátil em vinhos peruanos. Os resultados foram interpretados através da análise de componentes principais (PCA) para encontrar uma técnica que complementasse a informação coletada por cromatografia gasosa (GC) e cromatografia líquida (HPLC) e comparando os PCA obtidos de GC e HPLC com os resultantes do E-nose, descobriu-se que este classificou melhor as amostras. Foi possível diferenciar os vinhos da mesma uva e de uma variedade diferente. Além disso, foi possível detectar vinhos adulterados, o que contribui para a indústria do vinho no controle de sua produção, a fim de melhorar a qualidade desta bebida para o consumidor.

Simultaneous Determination of Formaldehyde, Benzeneand Sulfur Dioxide In Air by Cataluminescence / 分析化学

A novel method based on cross sensitivity of cataluminescence (CTL) on nano-Ti3CeY2O11 was proposed for simultaneous determination of formaldehyde, benzene and sulfur dioxide in air.The relations between the concentrations of formaldehyde, benzene and sulfur dioxide and their CTL intensities were respectively ascertained at three wavelengths.The accurate concentrations of formaldehyde, benzene and sulfur dioxide can be calculated by superimposed total CTL intensities.The three analysis wavelengths are 420 nm, 535 nm and 680 nm.The surface temperature of the sensitive materials is 280℃.The carrier gas flow rate is 130 mL/min.The detection limits (3σ) are 0.04 mg/m3 for formaldehyde, 0.05 mg/m3 for benzene and 0.10 mg/m3 for sulfur dioxide, respectively.The linear ranges of CTL intensity versus analyte concentration are 0.08-75.60 mg/m3 for formaldehyde, 0.1-101.40 mg/m3 for benzene and 0.3 to 115.00 mg/m3 for sulfur dioxide.The recoveries of 12 testing standard samples by this method are 96.4%-103.7% for formaldehyde, 97.8%-102.5% for benzene and 97.2%-103.3% for sulfur dioxide.Common coexisting substances, such as acetaldehyde, toluene, hydrogen sulfide, ammonia, methanol, ethanol and carbon dioxide, do not disturb the determination.The relative deviation of CTL signals of continuous 200 h detection for gaseous mixture containing formaldehyde, benzene and sulfur dioxide is less than 2%, which shows the longevity of the nanometer composite oxide to formaldehyde, benzene and sulfur dioxide.This method makes full use of the cross sensitive phenomenon, and can realize the on-line analysis of formaldehyde, benzene and sulfur dioxide in air.

A Gaseous Benzene and Trimethylamine Sensor Based on Cross Sensitivity on Nano-Zr3 Y2 O9 / 分析化学

A novel method based on cross sensitivity of cataluminescence (CTL) generated on the surface of a nanometer composite oxide was proposed for simultaneous determination of benzene and trimethylamine (TMA) in air. A variety of nanometer composite oxides based on Y2 O3 that showed catalytic activity to many gas molecules were synthesized. For the fabrication of the detector, nanometer composite oxide was directly coated on the ceramic rod to form a 0. 1-0. 15 mm thick layer. The ceramic rod with nanometer composite oxide was inserted into a quartz tube with an inner diameter of 10 mm. The temperature of nanometer composite oxide was controlled by the digital heater. When gas samples passed through the nanometer composite oxide in the quartz tube by the air flow, the CTL was generated during the catalytic oxidation on the surface of the nanometer composite oxide. The CTL signals were respectively recorded by two ultra weak chemiluminescence analyzers. The CTL intensity and selectivity for the determination of benzene and TMA on nano- Zr3 Y2 O9 which was characterized by TEM were bigger and better than those on other nanosized composite oxides. The optimum experimental conditions were tested. Selective determination was achieved at a wavelength of 440 nm for benzene and 540 nm for TMA. The surface temperature of the nanometer materials was about 313 ℃. The flow rate of air carrier was about 140 mL/ min. The limit of detection of this method was 0. 30 mg / m3 for benzene at 440 nm and 0. 70 mg / m3 for TMA at 540 nm. The linear range of CTL intensity versus concentration of benzene at 440 nm was 0. 8-105. 0 mg / m3 , benzene at 540 nm was 3. 0-130. 0 mg / m3 , TMA at 440 nm was 2. 5-232. 0 mg / m3 and TMA at 540 nm was 1. 2-156. 0 mg / m3 . The recovery of 5 testing standard samples by this method was 96. 8% -102. 3% for benzene and 97. 6% -103. 4%for TMA. Common coexistence matters, such as formaldehyde, ethanol, acetone, ammonia, sulfur dioxide and carbon dioxide, did not disturb the determination. The relative standard deviation (RSD) of CTL signals of a continuous 200 h detection of gas mixture of 50 mg / m3 benzene and 50 mg / m3 TMA was 2. 0% , which demonstrated the longevity and steady performance of nano-Zr3 Y2 O9 to benzene and TMA under this experimental conditions.

Identification of Saccharomyces cerevisiae strains for alcoholic fermentation by discriminant factorial analysis on electronic nose signals

An electronic nose (E-nose) coupled to gas chromatography was tested to monitor alcoholic fermentation by Saccharomyces cerevisiae ICV-K1 and Saccharomyces cerevisiae T306, two strains well-known for their use in oenology. The biomass and ethanol concentrations and conductance changes were measured during cultivations and allowed to observe the standard growth phases for both yeast strains. The two strains were characterized by a very similar tendency in biomass or ethanol production during the fermentation. E-nose was able to establish a kinetic of the production of aroma compounds production and which was then easy to associate with the fermentation phases. Principal Component Analysis (PCA) showed that the data collected by E-nose during the fermentation mainly contained cultivation course information. Discriminant factorial analysis (DFA) was able to clearly identify differences between the two strains using the four main principal components of PCA as input data. Nevertheless, the electronic nose responses being mainly influenced by cultivation course, a specific data treatment limiting the time influence on data was carried out and permitted to achieve an overall performance of 83.5 percent.

Application of Gold Hollow Nanospheres in Amperometric Formaldehyde Gas Sensor / 分析化学

The gold hollow nanospheres have been synthesized by sacrificE-template method and the obtained sample has been characterized by TEM, SEM and XRD. The amperometric formaldehyde gas sensor was assembled with gold hollow nanospheres as the active electrode material and 1 mol/L KOH solution as electrolyte. The equation of linear regression(y=16.63x+4.063×10-7, r=0.9989)between the oxidation current(y(A))and the concentration of formaldehyde(x/(mol/L)) was obtained at the formaldehyde concentration in the range of 0 to 2.23×10-6 mol/L. The sensitivity of the sensor with gold hollow nanospheres as active material increased by about 70% compared with the sensor made of nanoparticles which had the same gold-loading in the work electrode, this method exhibits an advantage of decrease in the cost of the noble metal. This kind of sensor shows potential application in formaldehyde gas detection in this range due to its excellent sensitivity, stable response and good linear relationship.

Recognizing frequency characteristics of gas sensor array / 西安交通大学学报·英文版

A novel method based on independent component analyzing (ICA) in frequency domain to distinguish the frequency characteristics of multi-sensor system is presented. The conditions of this type of ICA are considered and each step of resolving the problem is discussed. For a two gas sensor array, the frequency characteristics including amplitude-frequency and phase-frequency are recognized by this method, and cross-sensitivity between them is also eliminated. From the principle of similarity, the recognition mean square error is no more than 0.085.

Recognizing frequency characteristics of gas sensor array / 药物分析学报

A novel method based on independent component analyzing (ICA) in frequency domain to distinguish the frequency characteristics of multi-sensor system is presented. The conditions of this type of ICA are considered and each step of resolving the problem is discussed. For a two gas sensor array, the frequency characteristics including amplitude-frequency and phase-frequency are recognized by this method, and cross-sensitivity between them is also eliminated. From the principle of similarity, the recognition mean square error is no more than 0.085.