Detecting concentration differences in aromatic oils

200 University of Wolverhampton undergraduates rank-ordered samples of aromatic oils commonly used in complementary medicine in terms of their concentration in the air above an oil-soaked cotton ball. Each participant was assigned the task of discriminating between 5 microl, 10 microl, and 20 microl of oil absorbed onto cotton balls. 25 participants assessed each oil, and 8 oils were used. Cardamom, Rosemary, and Ylang Ylang were highly discriminable; however, discrimination of different concentrations of Chamomile, Cyprus, Geranium, Jasmine, and Lavender did not significantly differ from chance. These data provide useful indices for choosing aromatic oils for research purposes.