GC-MS Determination of Essential Oil in Anise with Solvent-free Microwave Assisted Extraction

20 g of sample of dried anise (crushed to pass 2.00 mm sieve) in a round-bottom flask was sprayed with water intermitently until its moisture content attained to 50%, and then treated with solvent-free microwave assisted extraction (SFME) in LWMC-204 Microwave Chemical Reactor at 180 W. The extract was dehydrated with anhydrous Na2SO4 and stored at 4 ℃, and was used for GC-MS analysis for composition of the essential oil. As shown by the analytical results and the comparative study between the data obtained by the methods of solvent-free microwave assisted extraction (SFME) and steam-distillation (SD), the following specific features were found with the SFME method: ① only 30 min were required to attain to the max. extraction rate of 7.71%; ② 25 compounds were found amounting totally to 98.94% (relative content); ③ more oxygen-containing monoterpenes were found as compared with the SD method; ④ main component of the essential oil was found to be trans-anisole which was the same compound found by SD, but the relative content (%) found by SFME was 1.4 times higher that found by SD.