Supercritical Carbon Dioxide Extraction of Volatile Components from Two Eucalyptus Species (E. spathulata and E. microtheca)

Abstract

Volatile oils from the leaves of E. spathulata and E. microtheca, cultivated in Iran, were obtained by hydro-distillation and supercritical (carbon dioxide) Extraction methods. The oils were analyzed by capillary gas Chromatography using flame ionization and mass spectrometric detections. The compounds were identified according to their retention indices and mass spectra (EI, 70eV). The effects of different parameters, such as pressure, temperature, modifier volume and Extraction time, on the supercritical fluid Extraction (SFE) of E. spathulata and E. microtheca oils were investigated. The results showed that for E. spathulata under a pressure of 100 atm, temperature 450C, 250 μl methanol and dynamic Extraction time of 25 min, Extraction was more selective for the 1,8-cineole, while for E. microtheca the pressure of 300 atm, temperature 550C, 0 μl methanol and dynamic Extraction time of 25 min, resulted more selectivity for 1,8-cineole. Thirty-two compounds were identified in the hydro-distilled oils of E. spathulata and E. microtheca. The major components of these oils were 1,8-cineole (44.5% and 14.4%) and α-pinene (20.2% and 10.3%), respectively. However, by using supercritical carbon dioxide under optimum conditions, only 1,8-cineole constituted 73.8% of the oil of E. spathulata and 39.3% of the oil of E. microtheca. The Extraction yield, based on hydro-distillation, was 3.77% and 0.79% (w/w) for E. spathulata and E. microtheca, respectively. Extraction yield, based on the SFE, varied in the range of 1.27–8.37% for E. spathulata and 1.23–5.90% (w/w) for E. microtheca, under different conditions.