Variation in the essential oils in different leaves of basil (Ocimum basilicum L.) at day time.

Essential oil molecules released from fresh leaves of sweet basil (Ocimum basilicum L.) were collected in Tenax traps and analysed using a TD-GC/MS. During daytime from 09.00 to 17.00, there were no differences in the con- tent and composition of total essential oils, however the percentage of eugenol increased slightly. Significant differences were found in both the total content and composition of essential oils between young and mature leaves. The total content in young leaves was four times higher than in mature leaves, with fourfold, twofold and sixtyfold differences in the rela- tive contents of linalool, eugenol and methyl eugenol respectively. There was no difference observed in the relative con- tent of 1,8-cineole. The results therefore suggest that the defining sampling procedure is important when comparing the essential oils between treatments. Key Word: Sweet basil, Ocimum basilicum, essential oil composition, linalool, eugenol, methyl eugenol, 1, 8-cineole.