Eucalyptus oil: Sources, analysis and chemical properties

Juhana Tjandra

A rapid and accurate solvent extraction - gas chromatographic analytical procedure was developed for the combined qualitative and quantitative chemical analysis of terpenoids from the leaves of eucalypts. The solvent extraction method was also applied successfully to the dry weight determination of the plant materials. The proposed method is efficient in time, cost and space. In comparative studies, it was shown to be more reliable than previous techniques. Using the new procedure, leaf oils of naturally occurring eucalypts in Western Australia were analysed systematically for the first time. Eucalyptus Kochii subsp. kochii and E. kochii subsp. plenissima were selected as the outstanding oil producing species yielding up to 8% on a dry weight basis. Analysis of the volatile oil revealed a composition of 90% 1,8-cineole and 5% other monoterpenoids. The significant seasonal trends and intraspecies variation in the essential oil yield were investigated over a two year period. The volatile oil composition patterns of various eucalypts obtained from high resolution capillary gas chromatography were shown to serve as finger prints, providing additional information at species and subspecies level to assist in the more difficult Eucalyptus taxonomic problems. Eucalyptus oil and its main components were investigated as potential cosolvents for aqueous ethanol/petrol fuel mixtures. Results showed that the incorporation of 1 to 3% eucalyptus oil or its main components such as 1,8-cineole increased the water tolerance and long-term phase stability of the fuel mixtures. Eucalyptus-derived fuels were found to have calorific values in the range of 4000 to 4500 kJ/kg similar to those of petroleum fuels. Liquid-liquid equilibrium data for the system unleaded petrol/ ethanol/water/1,8-cineole, and the ternary system ethanol/water/1,8-cineole were investigated isothermally. An apparatus replacing the less sensitive visual observation and facilitating cloud point determination was designed for this purpose. Ternary phase diagrams were determined, complete with tie-lines, thus fully characterizing the two-phase area. The tie-line data were correlated by the methods of Hand and Othmer-Tobias. A brief account of the history, economics and future viability of the eucalyptus oil industry is presented.

Eucalyptus oil: Sources, analysis and chemical properties

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