Material Analysis and Indoor Chemistry

Research project

Gas chromatography and olfactometry

A standard method used in order to differentiate between odour-active and odour-neutral substances is the combination of gas chromatography with olfactometry (GC/O). Individual substances and complex blends can be sensorially analysed using this method. The sensitive detector “nose” enables the recognition of substances which other methods of analysis, due to their low detection sensitivity, are unable to identify. 

© Fraunhofer WKI
Geruchsanalyse mittels GC/O-FID.

In our department, GC/O is used for material and indoor analytics in order to identify sources of odour nuisance and off-odours. The main focus here is placed upon the examination of differing consumer goods and materials through the application of GC/O-FID and the determination of the intensity of such products with the help of emission test chamber measurements. In this way, GC/O can additionally be applied for process and product optimisation.

Instrumental information and identification

The samples are placed in a desiccator (23°C) or directly in an emission test chamber and air samples are collected using Tenax TA adsorption tubes. The emitted substances can be gas-chromatographically analysed using the analysis device, formed by coupling the gas chromatography-olfactometry with a flame ionisation detector (GC/O-FID). At the end of the capillary column, the eluate is fragmented and, utilising the olfactory detection port (ODP), detected virtually parallel by the nose and the FID. The samples are inhaled repeatedly by several volunteers, in order to restrict the subjectivity.

The odour-active eluting components are marked and described with the help of voice-recognition software. The identification is carried out through external standardisation with the retention times and calculated indices of the individual substances as well as the classification of the odour impression. For this, an internal odour databank is implemented or the individual odour-active relations are measured directly as standards. Furthermore, the ODP chromatograms are compared with the recorded mass spectra from the samples.