Optimization of Hydrodistillation Dynamic Headspace Liquid Microextraction Method for the Determination Rosmarinus Officinalis Essential Oil Based on Central Composite Design

The combined extraction methods of hydrodistillation-dynamic headspace liquid phasemicroextraction (hd-dhlpme) coupled with gas chromatography-mass spectrometry (gc-ms)was applied for determination of essential oil components of rosmarinus officinalis. theextraction was carried out by sampling the headspace of water immersion of plant material at theboiling point of water. the extraction parameters including, syringe withdrawal rate, samplingvolume and sample weight were optimized by central composite design for the extraction ofessential oil in rosmarinus officinalis. the results obtained by experimental design comparedwith those of one-at-a-time method. as a result, i m l, of n-heptane containing n-heptadecane (asinternal standard) was chosen for the extraction of 3.9lg for 5.0 m l sampling volume with thesyringe withdrawal rate of 1.1 m l/s . a comparison of hd and hd-dhlpme, was made andshowed that the latter was useful for extraction and analysis of volatile compounds of aromaticplants too. the essential oil extracted and the components were identified by mass spectrometry.the main constituents of the essential oil were alpha-pinene (24.72 % ), 1,8-cineole (9.37 %),verbenone (9.23 %), camphor (9.02 %), borneol acetate (7.54 %) and comphene (5.30 %), borneol(5.23 %) .