TY - JOUR A1 - Tiebe, Carlo A1 - Miessner, H. A1 - Koch, B. A1 - Hübert, Thomas T1 - Detection of microbial volatile organic compounds (MVOCs) by ion-mobility spectrometry N2 - Traces of microbial volatile organic compounds (MVOCs) in air can indicate the presence of growth of moulds in the indoor environment. Ion-mobility spectrometry is a very promising method for detection of these MVOCs, because of its high sensitivity. For development of an in-situ method for detection of MVOCs, a portable ion-mobility spectrometer (IMS) was used and test gases of 14 MVOCs and their respective mixtures were investigated. IMS spectra were recorded as a function of concentration of MVOCs in air. Drift time and mobility of reactant ions formed in positive polarity mode were determined and correlated with the mass-to-charge ratio (m/z) of the MVOCs investigated. The estimated detection limit has a specific value for each MVOC and is in the range 3 to 96 µg m-3 (1 to 52 ppbV). Indoor trials show that IMS can indicate hidden mould growth. KW - Trace gas analysis KW - MVOCs KW - Ion-mobility spectrometry KW - Mould detection PY - 2009 DO - https://doi.org/10.1007/s00216-009-3147-4 SN - 1618-2642 SN - 1618-2650 VL - 395 IS - 7 SP - 2313 EP - 2323 PB - Springer CY - Berlin AN - OPUS4-20082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tiebe, Carlo A1 - Hübert, Thomas A1 - Rondeshagen, D. T1 - Ionen-Mobilitäts-Spektrometrie hilft bei der Kontrolle von Gewürzen PY - 2014 UR - https://www.laborpraxis.vogel.de/analytik/spektroskopie-und-photometrie/articles/438502/ SN - 0344-1733 SN - 1610-8256 SP - 1 EP - 11(?) PB - Vogel CY - Würzburg AN - OPUS4-30922 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tiebe, Carlo A1 - Hübert, Thomas A1 - Lorek, A. A1 - Wernecke, R. T1 - HUMItrace-Sensorsystem mit neuartigen planaren Spurenfeuchtesensoren N2 - Es wird ein Sensorsystem (HUMItrace III) zur Spurenfeuchtebestimmung in der Prozessmesstechnik vorgestellt. Die Bestimmung der Spurenfeuchte erfolgt mit neuentwickelten planaren Sensoren (HUMItrace-Sensoren) nach dem coulometrischen Messprinzip im Frostpunkttemperaturbereich von -80 °C bis -30 °C mit der Kalibriereinrichtung THG11 durch Mischen von trockenen und befeuchteten Teilgasströmen kalibriert. Die Gasfeuchte von Luft kann in diesem Bereich mit den HUMItrace-Sensoren mit einer erweiterten Unsicherheit von 2 K bestimmt werden. Die Sensoren können aber auch zur Gasfeuchtemessung in Wasserstoff, Stickstoff und Distickstoffmonoxid eingesetzt werden. Eine weitere Kalibriereinrichtung, THG-P12, generiert Prüfgase nach der Permeationsmethode; sie kann in das HUMItrace III Sensorsystem implementiert und zur vor-Ort-Kalibrierung der HUMItrace-Sensoren nach dem Standardadditionsverfahren genutzt werden. T2 - Temperatur 2013 - Verfahren und Geräte in der Temperatur- und Feuchtemesstechnik CY - Berlin, Germany DA - 05.06.2013 PY - 2013 SN - 3-9810021-8-0 SP - 257 EP - 262 AN - OPUS4-28732 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tiebe, Carlo A1 - Hübert, Thomas A1 - Lorek, A. A1 - Wernecke, R. T1 - New planar trace humidity sensor N2 - A new planar sensor element for continuous coulometric trace humidity measurements in industrial gases has been developed. In order to ensure precise measurements a calibration facility including a precision dew point hygrometer as a reference device was developed. The sensor can measure the humidity in the frost point temperature range of -20 °C to -80 °C and has an expanded uncertainty of 2 K, a fast reaction time and a settling time of the entire system from 15 to 30 min. T2 - IMCS 2012 - 14th International meeting on chemical sensors CY - Nuremberg, Germany DA - 2012-05-20 KW - Trace humidity KW - Coulometric principle KW - HUMITRACE sensor KW - Humidity measurement PY - 2012 SN - 978-3-9813484-2-2 DO - https://doi.org/10.5162/IMCS2012/3.4.2 SP - 294 EP - 297 PB - AMA Service GmbH CY - Wunstorf AN - OPUS4-27570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tiebe, Carlo A1 - Hübert, Thomas A1 - Koch, B. A1 - Ritter, U. A1 - Stephan, Ina T1 - Investigation of gaseous metabolites from moulds by ion mobility spectrometry (IMS) and gas chromatography-mass spectrometry (GC-MS) N2 - The metabolism of moulds results in the formation of various microbial volatile organic compounds (MVOCs). These substances can be used as an indicator for the presence of moulds in the indoor environment. Three different mould strains were cultivated on culture media and IMS spectra of gaseous mould metabolites were recorded using a portable mini system with a tritium source and a 5 cm drift cell. The headspace spectra are characteristic for mould species and their age. Typical gaseous components of the metabolites were identified and compared with results obtained from gas chromatography using a mass spectrometer detector. It was observed that the MVOCs formation depends on mould species and their growing stage with a maximum of MVOCs emission occurring during the first 10 days. These preliminary results show that IMS can be applied to detect MVOCs in indoor environment and indicate hidden mould growth. KW - Mould detection KW - MVOC KW - Biochemical sensor system KW - Ion mobility spectrometry KW - IMS KW - Gas chromatography KW - Mass spectrometry KW - Principal component analysis PY - 2010 DO - https://doi.org/10.1007/s12127-009-0035-8 SN - 1435-6163 VL - 13 IS - 1 SP - 17 EP - 24 PB - Springer CY - Berlin; Heidelberg AN - OPUS4-21234 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tiebe, Carlo A1 - Detjens, Marc A1 - Hübert, Thomas T1 - Messunsicherheit coulometrischer Spurenfeuchtesensoren N2 - Die Spurenfeuchte von technischen Gasen kann zuverlässig mit coulometrischen Feuchtesensoren bestimmt werden. Das Prinzip dieser Sensoren basiert auf der Absorption von Wasser in einer hygroskopischen Schicht und anschließenderelektrolytischer Zersetzung. Die Kalibrierung der Sensoren erfolgte mit einem Spurenfeuchtegenerator bei Frostpunkttemperaturen kleiner als -30 °C bzw. einem Volumenanteil kleiner als 376 µL·L-1. Die generierte Feuchte wurde zusätzlich zu den coulometrischen Sensoren mit einem Taupunktspiegelhygrometer, welches als Referenz diente, gemessen. Zwischen dem coulometrischen Sensorsignal und der gemessenen Referenzfeuchte wurde eine empirische nichtlinare Funktion gefunden. Die resultierende Kalibrierungsfunktion, die aus zwei Parametern besteht, wurde hinsichtlich ihrer Messunsicherheit bewertet. Zusätzlich erfolgt die Überprüfung der Kalibrierparameter mittels einfaktorieller Varianzanalyse (ANOVA). Die ANOVA zeigte, dass eine gemittelte Funktion für die Feuchtigkeitbestimmung in Stickstoff, Helium und synthetischer Luft für mehrere Sensoren angewendet werden kann. Mit coulmetrischen Sensoren ist es möglich, die Spurenfeuchte in technischen Gasen mit einer erweitereten Unsicherheit hinsichtlich der Frostpunkttemperatur kleiner als 2,1 K zu ermitteln. T2 - 8. VDI-Fachtagung Messunsicherheit CY - Erfurt, Germany DA - 15.11.2017 KW - Spurenfeuchte KW - Messunsicherheit KW - Gasfeuchte PY - 2017 AN - OPUS4-43238 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tiebe, Carlo A1 - Detjens, Marc A1 - Banach, Ulrich A1 - Hübert, Thomas T1 - Measurement uncertainty of coulometric trace humidity sensors N2 - Especially trace amounts of water vapour in gases can be reliably determined by coulometric trace humidity sensors. The principle of these sensors is based on water vapour absorption in a hygroscopic layer and its subsequent electrolytic decomposition. The calibration of sensors was performed in the humidity range, expressed as frost point temperature, from −30°C to −80°C . This range is equivalent to volume fractions smaller than 376 µL·L−1. Generated humidity was measured with coulometric sensors and a chilled dew point hygrometer that was used as reference. An empirical non-linear function was found between sensor signal and measured reference humidity. This function consists of two parameters with a measurement uncertainty. Both calibration parameters were checked by means of one-way analysis of variance. It showed that gas specific function can be used for humidity measurement in nitrogen, hydrogen, dinitrogen monoxide, compressed and synthetic air. It is possible to determine trace humidity in all tested gases with an expanded uncertainty less than 2.1 K (coverage factor k=2 ) regarding frost point temperature. KW - Trace humidity KW - Coulometric sensor KW - Measurement uncertainty KW - ANOVA PY - 2018 DO - https://doi.org/10.1515/teme-2018-0031 SN - 0171-8096 VL - 85 IS - 12 SP - 746 EP - 753 PB - De Gruyter CY - Oldenbourg AN - OPUS4-45959 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tiebe, Carlo A1 - Banach, Ulrich A1 - Hübert, Thomas A1 - Gawlitza, Kornelia A1 - Bartholmai, Matthias T1 - Development of a gas standard generator N2 - Pollution through emission of toxic gases is an increasing problem for the environment. It affects similarly agricultural, industrial and urban areas. In future, environmental emissions in ambient air must be monitored at even lower concentrations as nowadays. One environmental relevant compound is ammonia and its conversion product ammonium that have strong negative impact on human health and ecosystems. Most ammonia measurements in ambient air are performed in the range below 1000 nmol·mol-1 and thus there is a need for reliable traceable ammonia gas standards and in addition in situ analytical procedures for monitoring (in ambient air to avoid that thresholds are exceeded). Therefore, the use of reference materials is necessary for development accompanying test or for calibration, e. g. of structure-integrated sensors and mobile multi-gas sensors. The developed gas standard generator produces gas mixtures that comply with the metrological traceability for ammonia gas standards in the desired environmentally relevant measurement range. The method is based on the permeation of ammonia through a membrane at constant temperature and pressure. The resulting ammonia penetrant gas flow is then mixed with a carrier gas flow to generate a gas standard flow of known concentration. The dynamic rage is enlarged by using a two dilution steps. Depending on the permeation rate, generable molar fractions are possible in the range nmol·mol-1 to a few µmol·mol-1. We present the design of an ammonia gas standard generator and first results of the characterisation of its individual components supporting the uncertainty assessment according to GUM for stable gas concentrations in this range. The relative uncertainty of the generated ammonia gas standard is smaller than 4 % (k = 2). T2 - Colloquium of Optical Spectrometry (COSP) CY - Berlin, Germany DA - 27.11.2017 KW - Gas standard generator KW - Permeation method KW - Ammonia PY - 2017 AN - OPUS4-43337 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tiebe, Carlo A1 - Banach, Ulrich A1 - Hübert, Thomas T1 - VDI/VDE-Richtlinie für Multigassensoren N2 - Technische Richtlinien enthalten Empfehlungen sowie Anforderungen zum Stand der Technik zur Aufstellung von Bewertungskriterien und Behandlung wissenschaftlich-technischer Fragen. Sie fördern den Erfahrungsaustausch und Technologietransfer zwischen Entwicklern und Anwendern. In unserem Beitrag stellen wir die Richtlinie VDI/VDE 3518 vor. Diese Richtlinienreihe definiert Begriffe, beschreibt den Aufbau und klassifiziert Multigassensoren (Blatt 1), befasst sich mit den Anforderungen für das Unterscheiden, Erkennen und mengenmäßige Bestimmen von Gemischen gasförmiger Stoffe und die Prüfung von Multigassensoren (Blatt 2) und gibt Anleitung für geruchsbezogene Messungen mit „Elektronischen Nasen“ (Blatt 3). Multigassensoren können als elektronische Nasen in Anlehnung an den biologischen Geruchssinn zur Wahrnehmung und Charakterisierung von Gerüchen eingesetzt werden. Die Spezifik von Multigassensoren besteht darin, dass durch die Wahl und Betriebsweise der Sensoren eine Vielzahl von geeigneten Messsignalen erzeugt werden, aus denen mit mathematischen Verfahren die für die Anwendung gewünschten Informationen extrahiert werden. Dazu ist ein Training der Messeinrichtung mit Proben bekannter Eigenschaften notwendig. Diese Richtlinie soll Herstellern, Anbietern und Nutzern als ein Leitfaden Informationen und Erläuterungen für die korrekte und sichere Arbeit mit Multigassensoren liefern. Sie soll Prüflaboratorien und Anwendern helfen, bei der Beurteilung von Qualitätsmerkmalen einheitlich vorzugehen und dafür gemeinsame Randbedingungen anzugeben T2 - 7. Anwendertreffen Ionenmobilitätsspektrometrie CY - Reutlingen, Germany DA - 06.03.2018 KW - Elektronische Nase KW - Multigassensorik KW - Richtlinie PY - 2018 AN - OPUS4-44452 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tahri, K. A1 - Tiebe, Carlo A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Geographical provenience differentiation and adulteration detection of cumin by means of electronic sensing Systems and SPME-GC-MS in combination with different chemometric approaches N2 - The detection of the aroma and flavour volatile compounds of spices is key in product quality control. Accordingly, it is necessary to develop new electronic sensing systems for food adulteration control and authenticity assessment for protecting customer's health. In this work, the capability of the E-nose and VE-tongue in combination with SPME-GC-MS to correctly discriminate between several cumin samples of different geographical origins and to detect their adulteration, by using unsupervised and supervised chemometric tools, was evaluated. Regarding the aroma profile, eleven volatile compounds were characterized by SPME-GC-MS; all of them were found in cumin powder while only eight are found in cumin seeds. The main volatile compounds detected were b-pinene, m-cymene, g-terpinene, cuminaldehyde and cuminic alcohol, in different proportions depending on the cumin sample form (seed or powder). In summary, the results obtained are sufficiently encouraging as a starting point for the development of new electronic sensing systems with more improvement in the reliability of the sensor's performance as well as chemometric tools in order to deal with a complex dataset. KW - Voltammetric electronic tongue KW - Electronic nose KW - SPME-GC-MS KW - Chemometric tool KW - Cumin discrimination KW - Geographical origins KW - Adulteration detection PY - 2016 DO - https://doi.org/10.1039/c6ay01906d SN - 1759-9660 VL - 8 IS - 42 SP - 7638 EP - 7649 PB - RCS AN - OPUS4-38558 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tahri, K. A1 - Tiebe, Carlo A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Geographical classification and adulteration detection of cumin by using electronic sensing coupled to multivariate analysis N2 - The objective of this work is to report the improvement obtained in the discrimination of complex aroma and taste with subtle differences in odor and flavor, by the use of fast suitable procedures for the cases of measurements in the field demanding decision-making in real time. The proposed electronic sensing systems, formed by an E-nose and VE-tongue, were used to discriminate cumin cultivars from different geographical origins, as well as to quantify the cumin adulteration percentages by using unsupervised and supervised chemometric tools. Thus, the results obtained are sufficiently encouraging as a starting point for the development of new electronic sensing systems with more improvement such the reliability of the sensors’ performance as well as the chemometric tools in order to deal with a complex dataset. KW - VE-tongue KW - E-nose KW - Chemometric tools KW - Cumin discrimination KW - Geographical origins KW - Adulteration detection PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-409735 DO - https://doi.org/10.1016/j.protcy.2017.04.102 SN - 2212-0173 VL - 27 SP - 240 EP - 241 PB - Elsevier B.V. AN - OPUS4-40973 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tahri, K. A1 - Tiebe, Carlo A1 - Bougrini, M. A1 - Saidi, T. A1 - El Alami-El Hassani, N. A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Determination of safranal concentration in saffron samples by means of VE-tongue, SPME-GC-MS, UV-vis spectrophotometry and multivariate analysis N2 - An experimental investigation has been carried out to characterize and discriminate seven saffron samples and to verify their declared geographical origin using a voltammetric electronic tongue (VE-tongue). The ability of multivariable analysis methods such as Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA) to classify the saffron samples according to their geographical origin have been investigated. A good discrimination has reached using PCA and HCA in the VE-tongue characterization case. Furthermore, cross validation and Partial Least Square (PLS) techniques were applied in order to build suitable management and prediction models for the determination of safranal concentration in saffron samples based on SPME-GC-MS and UV-Vis Spectrophotometry. The obtained results reveals that some relationships were established between the VE-tongue signal, SPMEGC-MS and UV-Vis spectrophotometry methods to predict safranal concentration levels in saffron samples by using the PLS model. In the light of these results, we can say that the proposed electronic system offer a fast, simple and efficient tool to recognize the declared geographical origin of the saffron samples. T2 - IEEE Sensor 2015 CY - Busan, South Korea DA - 01.11.2015 KW - Chemometrics KW - Voltammetric electronic tongue KW - SPME-GC-MS KW - UV-vis Spectrometry KW - Saffron KW - Geographic differentiation PY - 2015 SN - 978-1-4799-8202-8 VL - CFP15SEN-USB SP - 68 EP - 71 PB - IEEE CY - Piscataway AN - OPUS4-36545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tahri, K. A1 - Tiebe, Carlo A1 - Bougrini, M. A1 - Saidi, T. A1 - El Alami El Hassani, N. A1 - El Bari, N. A1 - Hübert, Thomas A1 - Bouchikhi, B. T1 - Characterization and discrimination of saffron by multisensory systems, SPME-GC-MS and UV-Vis spectrophotometry N2 - Different electronic sensor systems coupled with multivariate data analysis were applied to characterize and classify seven saffron samples and to verify their declared geographical origin. The proposed electronic sensing consists of a low-cost electronic nose (E-nose) based on metal oxide semiconductor sensors and a voltammetric electronic tongue (VE-tongue) based on voltammetric sensors. The ability of multivariable analysis methods such as Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA) and Support Vector Machines (SVMs) to classify the saffron samples according to their geographical origin have been investigated. Both PCA and HCA have shown an overlapping of E-nose responses. Moreover, the SVM analysis of the E-nose database reached a 66.07% success rate in the recognition of the saffron sample odour. On the other hand, good discrimination has been reached using PCA and HCA in the VE-tongue characterization case, besides a 100% accuracy in the saffron flavour recognition was attained. To validate the proposed electronic sensing systems, analytical chemical methods such as SPME-GC-MS and UV-Vis spectrophotometry were used. These analytical methods could be helpful tools to identify the composition of volatile compounds of the analysed saffron samples. Moreover, UV-Vis spectrophotometry was also used to determine the non-volatile profile of the samples from different geographic origins. It is demonstrated that the electronic sensing systems' findings are in a satisfactory correlation with the analytical methods. In the light of these results, we might say that the electronic systems offer a fast, simple and efficient tool to recognize the declared geographical origin of the saffron samples. KW - Electronic nose KW - Voltammetric electronic tongue KW - SPME-GC-MS KW - UV-vis spectrophotometry KW - Saffron KW - Geographic differentiation KW - Multivariable analysis PY - 2015 DO - https://doi.org/10.1039/C5AY01986A SN - 1759-9660 SN - 1759-9679 VL - 7 IS - 24 SP - 10328 EP - 10338 PB - RSC Publ. CY - Cambridge AN - OPUS4-35174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hübert, Thomas A1 - Tiebe, Carlo A1 - Stephan, Ina A1 - Miessner, H. A1 - Koch, B. T1 - Detection of mould in indoor environments using a mini ion-mobility spectrometer system T2 - EUROSENSORS XXII CY - Dresden, Germany DA - 2008-10-07 KW - Mould detection KW - Fungus KW - Indoor air quality KW - MVOC KW - Biochemical sensor system KW - Ion-mobility spectrometry PY - 2008 SN - 978-3-00-025217-4 SP - 300 EP - 303 AN - OPUS4-18186 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Tiebe, Carlo A1 - Stephan, Ina T1 - Detection of fungal infestations of wood by ion mobility spectrometry N2 - During their growth on wood many fungi produce characteristic volatile organic compounds as secondary metabolites. These microbial volatile organic compounds (MVOCs) can be used as indicators of fungal growth even when such growth is concealed. In order to investigate the formation of these volatile metabolites on building materials, specimens of pine sapwood on agar media colonized by the dry-rot fungus Serpula lacrymans and a mixture of six moulds were examined. MVOCs from this fungal growth were studied over a period of up to half a year by ion mobility spectrometry (IMS) headspace analysis using a sensitive, portable IMS mini-device. The IMS headspace spectra from the growing fungal specimens obtained during this time span are differed from non-incubated wood specimens and indicate the presence of a mixture of MVOCs. The composition and amount of volatile metabolites of the fungi changed during cultivation. This was confirmed by a principal component analysis (PCA). Identification of different MVOCs in the headspace according to drift time and the mobility of ionized gaseous species in reference to GC-MS investigations were proposed. It was concluded that IMS can be used as a rapid and sensitive on-site method to indicate actively growing fungi concealed within wood. KW - Dry rot KW - Serpula lacrymans KW - Moulds KW - Concealed infestation KW - Ion mobility spectrometry KW - Fungal detection PY - 2011 DO - https://doi.org/10.1016/j.ibiod.2011.03.008 SN - 0964-8305 VL - 65 IS - 5 SP - 675 EP - 681 PB - Elsevier CY - Barking AN - OPUS4-23994 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Tiebe, Carlo A1 - Detjens, Marc A1 - Majewski, J. T1 - On-site calibration system for trace humidity sensors N2 - A portable device for calibration of trace humidity sensors and an adopted calibration procedure have been developed. The calibration device is based on humidity generation by permeating water through polymeric membrane tubes. Water vapour transmission rates for various polymers were experimentally determined in order to select the most suitable polymeric material. The developed trace humidity generator consists of a gas-flow polymeric hose immersed in a water reservoir thermostated by a sensorcontrolled heater. Mole fractions of water vapour between 1 µmol/ molˉ¹ and 350 µmol/molˉ¹ (equivalent to frost-point temperatures from -76 °C to -31 °C) were generated by varying either the operating temperature or gas flow. The operating temperature can be varied from 20 °C to 60 °C and kept stable within 0.1 K. Uncertainty analysis indicated that the trace humidity generator produces gas flows of constant humidity amounts with a relative expanded uncertainty less than 3.4% (k = 2) of the generated value. KW - Polymeric tubes KW - Measurements KW - Trace Humidity KW - Sensor calibration KW - Water vapour permeation PY - 2016 DO - https://doi.org/10.1016/j.measurement.2016.05.013 SN - 0263-2241 VL - 91 IS - 9 SP - 251 EP - 257 PB - Elsevier Ltd. AN - OPUS4-36762 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Hübert, Thomas A1 - Tiebe, Carlo A1 - Banach, Ulrich ED - Rodriguez Mendez, M. T1 - Electronic Noses for the Quality Control of Spices N2 - The chapter describes the application of electronic noses (multigas sensors) for the quality control of spices and spice mixtures. Electronic noses were successfully applied for headspace analysis of spices. It was demonstrated in many investigations that electronic noses can contribute to the characterization of spices and spice mixtures in order to distinguish spices and spice mixtures, differentiate by origin, growth seasons,and processing,indicate adulteration from original, detect mold infestation. Electronic noses can be used as a fast screening method to provide information about the product quality. However, it needs samples and methods for reference, careful training, and complex calibration to consider influencing and disturbing effects as well as the possible limitations of the instrumentation. The correlation to classical chemical analysis methods is always advisable. Machined olfaction methods are capable to support the sensory analysis; however, they cannot yet substitute them. KW - Spice KW - Electronic Nose KW - Multigas sensor KW - Quality control PY - 2016 SN - 978-0-12-800243-8 DO - https://doi.org/10.1016/B978-0-12-800243-8.00012-3 SP - Chapter 12, 115 EP - 124 PB - Academic Press CY - Oxford AN - OPUS4-35443 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hübert, Thomas A1 - Majewski, J. A1 - Banach, Ulrich A1 - Detjens, Marc A1 - Tiebe, Carlo T1 - Response Time Measurement of Hydrogen Sensors N2 - The efficiency of gas sensor application for facilitating the safe use of hydrogen depends considerably on the sensor response to a change in hydrogen concentration. Therefore, the response time has been measured for five different-type commercially available hydrogen sensors. Experiments showed that all these sensors surpass the ISO 26142 standard; for the response times t90 values of 2 s to 16 s were estimated. Results can be fitted with an exponential or sigmoidal function. It can be demonstrated that the results on transient behaviour depend on both the operating parameters of sensors and Investigation methods, as well as on the experimental conditions: gas change rate and concentration jump. T2 - 7th International Conference on Hydrogen Safety (ICHS 2017) CY - Hamburg, Germany DA - 11.09.2017 KW - Response time KW - Hydrogen sensor KW - Test facility KW - t90 value PY - 2017 SN - 978-88-902391 SP - 1251 EP - 1261 AN - OPUS4-47592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Detjens, Marc A1 - Hübert, Thomas A1 - Tiebe, Carlo A1 - Banach, Ulrich T1 - Temperature influence on coulometric trace humidity measurement N2 - Planar coulometric sensors were tested in humidified synthetic air at various gas temperatures. Generated frost point temperature in the gas ranged from -30 °C to -60 °C and were measured by coulometric sensors and in addition by a calibrated dew point hygrometer. The gas temperatures, which were measured by a calibrated Pt100 sensor, were set to -20 °C, 0 °C, 23 °C, 40 °C, 50 °C, and 60 °C during the experiments. Empiric nonlinear functions were calculated between the generated humidity and the sensor signals. In comparison to the measured signals at 23 °C, the sensor signals were lower at the other gas temperatures. The measurements at 60 °C showed indistinct results due to a great signal noise. The response behavior of the sensors was similar at 23 °C, 40 °C and 50 °C. In contrast to that, the sensors reacted slowly at a gas temperature of -20 °C and 0 °C. In summary, with coulometric sensors it was possible to measure continuously trace humidity with an expanded uncertainty below 2 K. T2 - IEEE Sensors 2017 CY - Glasgow, Scotland, UK DA - 30.10.2017 KW - Response behavior KW - Coulometric sensors KW - Trace humidity measurement KW - Temperature influence KW - Chemical reaction PY - 2017 SN - 978-1-5386-4056-2 SP - 1308 EP - 1310 PB - IEEE CY - Piscataway, NJ, USA AN - OPUS4-43241 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Detjens, Marc A1 - Hübert, Thomas A1 - Tiebe, Carlo A1 - Banach, Ulrich T1 - Coulometric trace humidity measurement in technical gases N2 - Trace humidity was measured by using miniaturized planar coulometric sensors in technical gases such as hydrogen, nitrogen, helium, nitrous oxide, and synthetic air. Frost point temperatures tf in the gases ranged from −60 °C to −30 °C, which is equivalent to a vapour mole fraction xv from 10 μmol mol−1 to 376 μmol mol−1. In addition, the generated humidity was determined by using a precision dew point hygrometer as reference. Nonlinear calibration functions were calculated that correlated electric current (sensor signal) and reference humidity. Parameters of functions were tested with one-way analysis of variances (ANOVA) to prove if all used sensors had a similar behavior in the same gas during experiments. Results of ANOVA confirmed that averaged functions can be applied for trace humidity measurement in nitrogen, helium, nitrous oxide, and synthetic air. The calculated functions were negligibly different for nitrogen, helium, and synthetic air. In humidified nitrous oxide, a minor change of parameters was observed due to lower electrical currents. In total contrast to that, the measured sensor signals were significantly higher in humidified hydrogen and each sensor required its own calibration function. The reason was a recombination effect that favoured multiple measurements of water molecules. Nevertheless, it was possible to measure continuously trace humidity in all tested gases by using coulometric sensors with an expanded uncertainty below 2 K (k = 2). KW - ANOVA KW - Trace humdity measurement KW - Coulometric sensors KW - Chemical sensors KW - Measurement uncertainty PY - 2018 DO - https://doi.org/10.1063/1.5008463 SN - 0034-6748 SN - 1089-7623 VL - 89 IS - 8 SP - 085004, 1 EP - 8 PB - American Institute of Physics (AIP) CY - Maryland (USA) AN - OPUS4-45956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Banach, Ulrich A1 - Tiebe, Carlo A1 - Hübert, Thomas T1 - Multigas sensors for the quality control of spice mixtures N2 - Spices have an important impact on daily aliment. Changes of their quality resulting in far reaching consequences in different foodstuffs and imply financial losing and even health hazard. In this study it is demonstrated that application of two different portable multi gas sensors (electronic nose and ion mobility spectrometer) supported by multivariate data analysis can contribute to ensure quality control of spice mixtures and to find out product adulteration. Headspace above spice mixtures for sausages and saveloy and product counterfeitings was investigated by a metal oxide based electronic nose (e-nose of KAMINA-type). Linear discriminant analysis (LDA) of sensor resistivity data was performed for differentiation. Simultaneously an ion mobility spectrometer (IMS) was coupled to the emission chamber for detection of gaseous components above spice mixtures. The measured spectra show differences between the two spice mixtures and were discussed using a principal component analysis (PCA). The two multigas sensors permit discrimination between the types of spice mixtures and can indicate product adulteration. Additionally, a headspace gas analysis by gas chromatography was performed to identify the main volatile components and to prove the chemical basis for the observed differences of the multi gas sensors. KW - Spice mixtures KW - Product adulteration KW - Electronic nose KW - Ion mobility spectrometer KW - Gas chromatography KW - Multivariate data analysis PY - 2012 DO - https://doi.org/10.1016/j.foodcont.2012.01.015 SN - 0956-7135 VL - 26 IS - 1 SP - 23 EP - 27 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-25402 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Banach, Ulrich A1 - Tiebe, Carlo A1 - Hübert, Thomas ED - Matteo Pardo, ED - Giorgio Sberveglieri, T1 - Application of electronic nose and ion mobility spectrometer to quality control of spice mixtures T2 - 13th International symposium on olfaction and electronic nose CY - Brescia, Italy DA - 2009-04-15 KW - Electronic nose KW - Ion mobility spectrometer KW - Spice mixtures KW - Product adulteration KW - Multivariate data analysis PY - 2009 SN - 978-0-7354-0674-2 N1 - Serientitel: AIP conference proceedings – Series title: AIP conference proceedings VL - 1137 SP - 301 EP - 302 AN - OPUS4-19572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -