Solid phase microextraction of volatile constituents from individual fresh Eucalyptus leaves of three species

Abstract

Methyl polysiloxane solid-phase microextraction fibres were used for ten minutes to adsorb volatile constituents from headspace above all or part of a single cut up fresh eucalyptus leaf kept warm at 37 degrees C. The fibres were desorbed at 200 degrees C for programmed gas chromatography (40-187 degrees C) on a methyl polysiloxane capillary. Substances were identified by mass spectra and/or authentic sample retention. Results do not correspond to published values for steam distilled oils, being richer in sesquiterpenes, of which three are common to three different species; and also in esters in two species. Five Eucalyptus citriodora leaves from the same tree over different months gave very similar analyses to a fibre in 10 min of 72.9-80.5% citronellal, 3.5-5.4% citronellol, 1.0-3.8% citronellyl acetate, 9.2-11.8% caryophyllene and 1.4-1.7% bicyclogermacrene. Six E. nicholii leaves yielded 67.2-73.7% cineole and 4.6-9.7% limonene along with 10.5-16.5% sesquiterpenes, mostly hydrocarbons, particularly bicyclogermacrene. E. globulus leaves gave only 54.0-61.3% cineole, with 19.5-24.3% alpha-pinene, 6.7-9.1% limonene and 2.1-5.4% alpha-terpinyl acetate; along with 3.6-7.7% sesquiterpenes, particularly aromadendrene, but no bicyclogermacrene.