Comparative analysis of the oil and supercritical CO 2 extract of Artemisia sieberi

Abstract

Essential oils of aerial parts of Artemisia sieberi obtained by hydrodistillation and supercritical carbon dioxide extracts obtained under different conditions were compared with regard to their major components. The supercritical fluid extraction (SFE) experiments were carried out in the pressure range of 10.1–30.4 MPa, the temperature range of 308–338 K, the dynamic extraction time of 15–35 min, and modifier volume of 0–500 μl. An experimental design was carried out to map the effects of different parameters on the extraction yield of the active components and to determine the optimal conditions for the extraction of camphor from A. sieberi using SFE. The optimization of supercritical fluid extraction conditions has been carried out by Taguchi method using a three level orthogonal array design with an OA 9 (3 4) matrix. Based on direct observation analysis, the highest yields for SFE were obtained at a pressure of 30.4 MPa, a temperature of 318 K, a dynamic extraction time of 25 min and in the absence of methanol as modifier. On the other hand, under these same conditions except a slightly higher temperature of 328 K extraction was more selective for the extraction of camphor. The chemical compositions of the SFE extract were identified by GC–MS and determined by GC–FID and then, compared with the essential oils obtained by hydrodistillation. The major compounds of oil obtained by hydrodistillation were camphor (54.7%), camphene (11.8%), 1,8-cineol (9.9%), β-thujone (5.7%) and α-pinene (2.5%). However, by using the supercritical carbon dioxide in optimum conditions, only two components represented more than 80% of the extract. The oil yield, based on the hydrodistillation was 1.7%, and the extracts of desired analytes based on the SFE varied in the range of 1.6–14.0% W/W under different conditions. The Chemical analysis revealed that components extracted under different SFE conditions possessed widely different percentage of constituents. The results indicated that by using the suitable extraction conditions, SFE is more selective than the conventional hydrodistillation method in the extraction of essential oil and the preservation of its quality.