Gas Sensors Food and Feed Safety at the IME Seidel Seidel Seidel Seidel Seidel Seidel 1st FoodSpot Workshop 2009 January 22nd, Aachen / Germany Dr. Mark Bücking
Food and Feed Safety Aim: Development and Improvement of Detection Methods (Environment, Food, Feed, Consumer Gods, Soil) Trace analysis and fast detection methods (M. Buecking) sensitive reproducible cheap fast long-living robust and simple biochemical and molecular biology based methods (B. Seidel)
Food and Feed Safety Research Areas Dr. Mark Bücking Complex reference analysis of organic residues Sensor 1 2000 Hz Flavour research Sensor 8 1500 1000 500 Sensor 2 Sensor 7 0 Sensor 3 Fast detection methods e.g. online detection of volatiles Gas Sensors / Electronic Nose Sensor 6 Farm-side Pa-ripe Sensor 5 Pa-unripe Sensor 4 Transport Food Chain Management check check Process-control check check
Gas Sensors - research projects Food quality control fruit, vegetables, meat, fish harvesting, processing, transport, storage Microorganisms Air quality identification by their volatile metabolism products identification of pollutants
Gas Sensors the principle sample input Sensitive layer Transducer Signal & Output
Electronic nose Gas Sensors the definitions An instrument which comprises an array of electronic chemical sensors with partial specificity and an appropriate pattern recognition system capable of recognizing simple or complex odours (Gardner, J.; Bartlett, P.; Sens. Actuators 18, 211-220) Metal Oxide Sensors when volatile compounds are adsorbed onto the surface of the semiconductors this generates a change in the electrical resistance which varies with the type of volatile compound and its concentration. O 2 SnO 2 O -
Gas Sensors the starting point Area [mv*min) Sampling time Sample prep. Data evaluation Chromatogram overlay 2 and 14 days of storage time
Gas Sensors conclusion Area [mv*min) time Do I know all the components in the headspace and their major interferants Do I know which components are responsible for the effect Do I know the concentration range typical of the problem I want to solve If I do not have this information it can be very dangerous and misleading to start any type of measurement with an electronic nose system
Gas Sensors: measurement system Setup 1 sampling 2 drying agent 3 GC column 4 gassensor array 5 data evaluation Fh-IPM
Gas Sensors: results 1,40 1,35 Methyl pyrrole and Ethyl butyrate Cooperation with Fh-IPM 1,30 R/R 0 1,25 1,20 1,15 1,10 1,05 Pinene Limonene concentrations: 720 ppb Methyl pyrrole 399 ppb Ethyle butyrate 66 ppb Pinene 22 ppb Limonene 1,00 T operate = 450 C 0,95 0,90 0 5 10 15 20 25 30 time/min reaction of IPM CTO sensor Very sensitive fast selective reproducible easy handling
Gas Sensors: example traceability Classification of peanuts Classical sample A B C Chemical assay method peroxide value (0.125mmol O 2 /kg) acid value (mg KOH/g) free fatty acids in fat (g/100g, calc. as oleic acid) n.n 11.8 15.1 0.39 0.63 0.71 0.20 0.32 0.36 Fatty acids (g/100g) saturated fatty acid 13.7 18.2 18.5 unsaturated fatty acid 80.0 44.7 45.9 polyunsaturated fatty 6.3 37.1 35.6 acid trans fatty acids <0.1 <0.1 <0.1 Gas Sensor A B B old C 30 20 10 0-60 -40-20 0 20 40 60 80-10 -20-30 -40-50 Scores for PC #1 (72,8%) Routine analysis is not able to clarify origin and age volatile compounds were identified and used as indicator of origin and freshness
Gas Sensors: example food safety Detection of bacteria contamination Abundance 210000 200000 6.73 TIC: Pputida2.D Pseudomonas putida - SnO2+Pt (12V) 190000 180000 170000 3410000 160000 150000 3390000 140000 130000 120000 110000 100000 90000 80000 70000 60000 50000 40000 30000 20000 10000 MeSH 5.59 12.21 16.54 6.00 8.00 10.00 12.00 14.00 16.00 Widerstand R 3370000 3350000 3330000 3310000 3290000 Propan-1-ol MeSH Aceton EtOH 1 22 43 64 85 106 127 148 169 190 211 232 253 274 295 Zeit [sec] Time--> gas chromatography 48h Metal oxide sensor 6h Routine analysis is much more time intensive volatile compounds were identified and used as indicator of bacteria species
Gas Sensors conclusion Gas Sensors can provide rapid sample discrimination Variables of the system are well known Nature of test and analyte are important Vendors tend to oversell this technology for any type of application Not possible! Important: transfer from technology platform to industry device handheld.autosampling.long term stability.etc
THANK YOU Dr. Mark Bücking Fraunhofer IME Auf dem Aberg 1 57392 Schmallenberg-Grafschaft Germany Tel.: ++49 2972 / 302 304 Fax: ++49 2972 / 302 319 Mobile: ++49 172 825 77 33 Email: mark.buecking@ime.fraunhofer.de http://www.ime.fraunhofer.de http://www.foodresearch.de