Electronic nose: current status and future trends.

Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany.
Chemical Reviews (Impact Factor: 41.3). 03/2008; 108(2):705-25. DOI: 10.1021/cr068121q
Source: PubMed
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    ABSTRACT: One of the main problems when working with electronic noses is the lack of reproducibility or repeatability of the sensor response, so that, if this problem is not properly considered, electronic noses can be useless, especially for quantitative analyses. On the other hand, irreproducibility is increased with portable and low cost electronic noses where laboratory equipment like gas zero generators cannot be used. In this work, we study the reproducibility of two portable electronic noses, the PEN3 (commercial) and CAPINose (a proprietary design) by using synthetic wine samples. We show that in both cases short term instability associated to the sensors' response to the same sample and under the same conditions represents a major problem and we propose an internal normalization technique that, in both cases, reduces the variability of the sensors' response. Finally, we show that the normalization proposed seems to be more effective in the CAPINose case, reducing, for example, the variability associated to the TGS2602 sensor from 12.19% to 2.2%.
    Sensors 06/2014; 14(6):10514-10526. · 2.05 Impact Factor
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    ABSTRACT: The overall metabolic state of an individual is reflected by emitted volatile organic compounds (VOCs), being gaseous carbon-based chemicals. In this review, we will describe the potential of VOCs as fully non-invasive markers for the detection of neoplastic lesions of the colon. VOCs are detected by our sensory olfactory nerves and form the molecular basis for our sense of smell. As such we emit our own individual odour-fingerprint or so-called "smellprint". This may change over time, in response to any alteration in metabolism such as modifications caused by (gastro-intestinal) infection, inflammation, external factors such as medication and diet, or development of neoplastic disease like colorectal cancer. This means that analysis of VOCs can provide a fully non-invasive metabolomics biomarker profile which could be used as a diagnostic tool. Thus far canine scent detection, Gas Chromatography Mass Spectrometry and electronic nose technologies allow for discrimination between patients with and without colorectal cancer and also its precursor ((advanced) adenoma) with promising accuracy. The challenge for future research is to identify specific biomarkers driving these signals. This enables the development of primed sensors tailored towards accurate identification of volatiles specific to colorectal cancer and adenomas. Such a technique may allow non-invasive monitoring of response to therapy and could revolutionize screening practices for colorectal cancer and potentially many other (gastro-intestinal) diseases.
    Clinical gastroenterology and hepatology: the official clinical practice journal of the American Gastroenterological Association 05/2014; · 5.64 Impact Factor
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    ABSTRACT: In Korean rice wine (makgeolli) model, we tried to develop a prediction model capable of eliciting a quantitative relationship between initial amino acids in makgeolli mash and major aromatic compounds, such as fusel alcohols, their acetate esters, and ethyl esters of fatty acids, in makgeolli brewed. Mass-spectrometry-based electronic nose (MS-EN) was used to qualitatively discriminate between makgeollis made from makgeolli mashes with different amino acid compositions. Following this measurement, headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (GC-MS) combined with partial least-squares regression (PLSR) method was employed to quantitatively correlate amino acid composition of makgeolli mash with major aromatic compounds evolved during makgeolli fermentation. In qualitative prediction with MS-EN analysis, the makgeollis were well discriminated according to the volatile compounds derived from amino acids of makgeolli mash. Twenty-seven ion fragments with mass-to-charge ratio (m/z) of 55 to 98 amu were responsible for the discrimination. In GC-MS combined with PLSR method, a quantitative approach between the initial amino acids of makgeolli mash and the fusel compounds of makgeolli demonstrated that coefficient of determination (R2) of most of the fusel compounds ranged from 0.77 to 0.94 in good correlation, except for 2-phenylethanol (R2 = 0.21), whereas R2 for ethyl esters of MCFAs including ethyl caproate, ethyl caprylate, and ethyl caprate was 0.17 to 0.40 in poor correlation.Practical ApplicationThe amino acids have been known to affect the aroma in alcoholic beverages. In this study, we demonstrated that an electronic nose qualitatively differentiated Korean rice wines (makgeollis) by their volatile compounds evolved from amino acids with rapidity and reproducibility and successively, a quantitative correlation with acceptable R2 between amino acids and fusel compounds could be established via HS-SPME GC-MS combined with partial least-squares regression. Our approach for predicting the quantities of volatile compounds in the finished product from initial condition of fermentation will give an insight to food researchers to modify and optimize the qualities of the corresponding products.
    Journal of Food Science 05/2014; · 1.78 Impact Factor

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