Correlation analyses of detection thresholds of four different odorants.

The detection threshold task of the Sniffin` Sticks can be conducted using two different odorants - n-butanol or phenylethyl alcohol (PEA). Previous studies show contradictory results regarding the correlation analysis of the two odorants. The current study investigated the relationship between PEA and n-butanol with respect to previous findings and subject population. We compared four different odorants (PEA, n-butanol, isoamyl butyrate, isobutanol) in an olfactory detection threshold task depending on subject population. Test odorants were applied to 73 healthy subjects. The experiment was divided into two sessions performed on two different days. The correlation coefficient between individual thresholds of PEA and n-butanol was not significant when exclusively normosmic subjects were included, but significant when additionally hyposmic, older subjects were studied. Comparable results were found for the analysis of the odorants n-butanol and isoamyl butyrate. Correlation between n-butanol and isobutanol was significant, both for exclusively normosmic, and additionally older, hyposmic subjects. The analyses of all other odorants revealed no significant correlations. Results give explanations for previous contradictory findings regarding investigations of PEA and n-butanol in a detection threshold task, and indicate that a formal validation of the Sniffin` Sticks with PEA as odorant is required.