Odour assessment by GC- Olfactometry

GC-Olfactometry (GC/O) is a remarkable technique that combines the chemical information typically obtained from gas chromatography with the sensory information provided by the human sensory system.
By combining the responses of a chemical detector with those of a GC-Olfactometry panellist, it is possible to highlight the odour-relevant compounds (i.e. identify which compounds smell), mark their odour contribution (i.e. know what they smell like) in the air sample. This can be applied to both, odour emissions and industrial products, foodstuffs and aromas.

By adding a sniffer port to the gas chromatograph, through which the eluted compound passes, suitably humidified and cooled, panellists can detect the compounds exiting the column (odour present or not), are able to measure the duration of the odour activity (start to end), describe the quality of the odour perceived and quantify its intensity.

When the operator smells, he activates a joystick that generates a signal on the analytical trace and pronounces the odour descriptor in the microphone: this generates the olfactogram, a sequence of squared peaks that show the quality of each perceived odour; once the olfactogram is overlaid on the chromatogram, the analyst can proceed to identify the odorous molecules by searching the system’s mass spectral library.

The technique, which involves the analysis of an odour-active compound based on stepwise dilution to threshold until no significant odour is detected by panellist, was developed by Werner Grosch called AEDA (Aroma Extract Dilution Analysis) and by Terry Acree called CharmAnalysis for the food industry. In our odour laboratory, this technique has also been applied in the environmental and industrial fields to identify substances responsible for unpleasant odours in manufactured goods and in the ambient air.