Optimisation of supercritical fluid extraction of essential oil components of Diplotaenia cachrydifolia: Box-Behnken design.

Essential oil of Diplotaenia cachrydifolia cultivated in Iran was obtained by supercritical fluid extraction (SFE) method. The oils were analysed by capillary gas chromatography using flame ionisation and mass spectrometric detections. The compounds were identified according to their retention indices and mass spectra (EI, 70 eV). The effects of different parameters, such as pressure, temperature, modifier volume and extraction times (dynamic and static), on the SFE were inspected by a fractional factorial design (2(5-2)) to identify the significant parameters and their interaction. It showed that static and dynamic times had no effect on the extraction. Finally, a Box-Behnken design was applied to obtain the optimum condition of the significant parameters. The optimal condition was obtained as 30.2 MPa for pressure, 65.6°C for temperature and 258.4 µL for modifier volume. The main components that were extracted with SFE were dillapiole (35.1%), limonene (33.5%) and α-calacorene (25.5%).