comparison of hydrodistillation, microwave hydrodistillation and solvent free microwave methods in analysis of the essential oils from aerial parts of haplophyllum robustum bge. by gc/ms method

the genus haplophyllum, which belongs to the rutaceae family, includes 18 species in iran. in this study, after collecting plant material, botanical identification and suitable drying, the essential oils from aerial parts of haplophyllum robustum bge. were extracted by three different isolation techniques, conventional hydrodistillation (hd), microwave-assisted hydrodistillation (mahd) and solvent free microwave extraction (sfme)  and analyzed by gas chromatography and gas chromatography coupled to mass spectrometry. the main components of three essential oils were sabinene (28.9%-31.5%), β- phellandrene (11.0%-14.6%), 1,8- cineole (7.2%-11.0%), 3,5- dimethoxy toluene (5.1%-14.2%), β- pinene (7.3%-8.9%) and terpinene-4-ol (5.8%-6.2%). higher amounts of oxygenated monoterpenes such as 1,8-cineole, camphor and terpinene-4-ol were present in the oil of mahd and sfme (21.1% and 21.0%, respectively) in comparison with hd (19.0%). however, hd oil contained more monoterpene hydrocarbons such as sabinene, β- phellandrene, β- pinene (72.6 %) than sfme and mahd extracted oils (67.9% and 62.8%, respectively). mahd and sfme offered substantial advantages over conventional hd. a similar extraction yield was achieved at significantly shorter extraction time when using mahd and sfme instead of hd. also microwave irradiation significantly reduced the extraction time  and did not adversely influence the composition of the essential oil. mahd and sfme is also more environment-friendly than hd. compared with many solvent extraction techniques, such as soxhlet, solvent extraction, and accelerated solvent extraction, mahd and sfme is a modern, green, and rapid approach