Abstract |
The report concludes the second year of a research program to chemically identify the odor components of diesel exhaust. The two-stage gas chromatographic method for resolution of the odor fractions has been refined using an efficient GC fraction trapping method and applied it with great success to the oily-kerosene odor fraction obtained from the first-stage, liquid-column chromatography (LCC) separation. The odors of the individually resolved compounds were characterized and their structure determined by high resolution mass spectrometry. Using this approach, together with quantitative odor studies on selected reference components, the chemical structure of the principal components responsible for the characteristic oily-kerosene portion of diesel exhaust odor has been determined. The chemical classes associated with the odor in this complex are: alkyl benzenes, indans/tetralins, and indenes. Alkyl naphthalenes constitute a major portion of the mass of the oily-kerosene fraction but are not a direct major odor contributor. Some limited success was achieved in applying the techniques described above to the smoky-burnt odor fraction and several individual odor species were identified. (Author) |