Chemical Compositions of the Essential Oils from the Aerial Parts ofAchillea wilhelmsiiUsing Traditional Hydrodistillation, Microwave Assisted Hydro- distillation and Solvent-Free Microwave Extraction Methods: Comparison with the Volatile Compounds Obtained by Headspace Solid-Phase Microextraction

Chemical profiles of the essential oils and volatile compounds from the aerial parts of Achillea wilhelmsii C. Koch (Compositae) obtained through hydrodistillation (HD), solvent-free microwave extraction (SFME), microwave assisted hydrodistillation (MAHD) and headspace solid-phase microextraction (HS-SPME) methods were subsequently investigated by means of GC and GC-MS instruments. A total of 22, 18, 22 and 22 components were identified in the chemical profiles, representing 93.6 %, 93.0 %, 92.4 % and 94.9 % of the total compositions when using the HD, HS-SPME, SFME and MAHD methods, respectively. In all samples, more than forty percent of the total structure consisted of oxygenated monoterpenes. In addition, the second rank of natural compounds are due to monoterpene hydrocarbons by SFME, MAHD and HS-SPME approaches while in the oil obtained by HD, oxygenated sesquiterpenes are the next most common ones. Moreover, 1,8-cineole was the main constituent of the hydrodistilled oil whereas camphor was the most frequently occurred compound using SFME, MAHD and HS-SPME methods.