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Gas sensor array for low-cost gas chromatography in food industry processes

: Bauersfeld, M.-L.; Peter, C.; Wöllenstein, J.; Bücking, M.; Bruckert, J.; Steinhanses, J.

AMA Fachverband für Sensorik e.V., Wunstorf:
SENSOR 2009, 14th International Conference on Sensors, Technologies, Electronics and Applications. Vol.1 : Nürnberg, Germany, 26 - 28 May 2009; Proceedings; Part of Sensor + Test Conference 2009
Wunstorf: AMA Service, 2009
ISBN: 978-3-9810993-4-8
International Conference on Sensors, Technologies, Electronics and Applications (SENSOR) <14, 2009, Nürnberg>
Sensor + Test Conference <2009, Nürnberg>
Fraunhofer IPM ()
Fraunhofer IME ()
gas chromatography; gas sensor array; food processing; Locochrom

Today, food quality plays a more and more significant role for the consumer. Therefore fast monitoring of food quality in the industry gets more important. To protect consumers and always ensure the optimum grade of quality, critical steps during production have to be controlled, to recognise and eliminate failures. Conventional analytical methods are mostly complex and expensive. In the past decade, activities directed towards development of low cost chromatographic measurement system using metal oxide gas sensors as detectors have increased substantially.1-2 However, a continuing drawback of such implementations has been the incompatibility of the chromatographic column with ambient air. Novel chromatographic columns allow measurements at room temperature and ambient air and enable the use of low-cost semiconductor gas sensors as detector unit in the gas chromatographic system. Furthermore the combination of different sensors in a single array offers the possibility to detect aromatic flavours which are, due to their similar chemical behavior, not automatically separable by the used chromatographic column. Such a low-cost gas chromatographic measurement system with gas chromatographic column and the sensory unit was set up. Different aromatic compounds occurring in food industry processes and gases which are enable inferences of food quality have been investigated. For the lab tests exemplary compounds like methyl pyrrole, hexanale, ethyl butyrate, pinene and limonene as well as ethylene and methyl mercaptan have been chosen. Out of these seven, ethyl butyrate and hex anale as well as ethyl butyrate and methyl pyrrole are not separable by the retention period through the chromatographic column. For the selection of the gas sensors commercial as well as self produced sensors have been tested. The goal was that the gas sensor array composes a well-defined fingerprint for each aromatic compound. A calculated Principal Components Analysis demonstrates that the selected sensor array can differentiate the aromatic flavours. The presented measurement system enable reliable and repeatable gas concentrations, down into the ppb-range are detectable, as well as assignable to the aromatic flavours. Next to food industry, similar processes in the pharmaceutical area offers further markets for the novel gas chromatographic measurement system.