The use of a non-equilibrated solid phase microextraction method to quantitatively determine the off-notes in mint and other essential oils

The undesirable top notes or off-notes found in mint, clary sage, and cedarwood oils could be quantitatively determined using a nonequilibrated solid phase microextraction/gas chromatography/selected ion monitoring/mass spectrometry (SPME/GC/SIM-MS) technique. Using the low threshold components, dimethyl sulfide, 2-methylpropanal, 2-methylbutanal, and 3-methylbutanal, which are associated with the off-notes of these oils, their levels could be reproducibly quantitatively determined. The highest level of off-notes was found in a sample of Scotch spearmint oil where the levels of the four constituents were, dimethyl sulfide (238 (mu)g g^-1), 2methylpropanal (286 (mu)g g^-1), 2-methylbutanal (1048 (mu)g g^-1) and 3-methylbutanal (1489 (mu)g g^-1). These quantitative results in combination with sensory evaluations could provide for a powerful overall assessment of essential oil quality.