Determination of 24 Micro Aromatic Substances in Rosemary Hydrosol by Gas Chromatography

The 10 mL of the sample was taken, and 0.5 mL of carbon tetrachloride was added. After extraction by shaking for 5 min, and settling, the lower organic phase was collected. The extraction was repeated again and the organic phases were combined, which was dehydrated by the anhydrous sodium sulfate for the determination by gas chromatography. Using DB-WAX quartz capillary chromatographic column as the stationary phase, separation was made under programmed temperature conditions, detection was made by hydrogen flame ionization detector, and quantification was made by external standard method. It was shown that 24 common aromatic substances could achieve baseline separation within 31.0 min, with resolution greater than 1.5. Linear relationships between values of the mass concentration and peak area of targets were kept in the range of 10.0-200.0 mg·L⁻¹, with detection limits (3S/N) in the range of 0.05-0.10 mg·L⁻¹. Test for recovery was made according to the standard addition method, giving recoveries in the range of 80.9%-118%, and RSDs (n=6) of the determined values ranged from 0.35% to 5.0%. The proposed method was used for the analysis of semi-finished products and finished products of hydrosol. There were differences in the types and contents of the main aromatic substances in the semi-finished products of hydrosol prepared by imported and domestic rosemary leaves, which may be due to differences in rosemary varieties. The main aromatic substances and their contents in the semi-finished products of rosemary hydrosol prepared by domestic rosemary leaves were basically the same, the contents of which were higher than those of commercially available finished products of hydrosol, and it was speculated that the latter may be diluted or modulated from the former.