Pattern display for characterisation of trace amounts of odorants discharged from nine odour sources

The odorants discharged from nine odour sources were classified into eight compound groups and were analysed by a systematic gas-chromatographic technique. The characterisation of trace amounts of the odorants was carried out by using the values for new proposed units (pOUm, pOUa, logOU, OUt and OU; all terms are dimensionless) based on the ratio of the detected concentration to the odour recognition threshold concentration. The graphical representation of these data is effective for rapid recognition of the whole state. A polar co-ordinate pattern display was also proposed for the explanation of the relationship between odour characteristics (odour quality and intensity) and chemical analysis data of the odorants responsible for each odour discharged from nine odour sources. The calculated pOUm and pOUa values of eight odorant groups were plotted on polar co-ordinate circular odour charts. These charts illustrated a characteristic pattern and it was found that the shapes and sizes of each odour chart could characterise the quality and intensity of each odour from the nine odour sources. This was confirmed by investigating examples of processes or factories belonging to the nine odour sources.