A Comparison of Selected Analytical Approaches to the Analysis of an Essential Oil

Abstract

Four gas chromatograph-based methods have been evaluated for their ability to provide qualitative and quantitative information on the characteristics of the components of the essential oil of Virginia cedarwood (Juniperus virginiana L.). Each method was found to possess certain strengths and limitations in providing the desired endpoints. Direct injection of solutions of the essential oil in an organic solvent provided very precise values for the percentage contribution. Solid-phase microextraction (SPME) employing a poly(dimethylsiloxane) ®bre provided information as to the distribution of major and minor volatile compounds in the headspace above the oil sample. Dynamic headspace analysis provided similar information, but both methods provided dierent perspectives on the constituency of the headspace. Gas-tight sampling of the headspace provided yet another viewpoint on the components in the headspace above the cedarwood oil. The exposure time of the ®bre in the SPME experiment and the sweep time of the dynamic headspace experiment were found to have a very signi®cant impact on the resulting distribution pro®le of the volatile compounds. Explanations as to the causes and implications of these results on the qualitative and quantitative analysis of essential oils were provided. Therefore, the desired analytical endpoint should dictate the type of gas chromatographic approach employed. For example, if information concerning the components responsible for the aroma of an essential oil is desired, then gas-tight sampling will provide a precise assessment of the distribution of those volatile components. On the other hand, dynamic headspace analysis and SPME will provide valuable qualitative information about all of the components of essential oils. Direct injection into a GC will provide the best quantitative information on the components of the essential oil. # 1997 by John Wiley & Sons, Ltd.

Antibacterial Activity of Thymus vulgaris L. Essential Oil Vapours and Their GC/MS Analysis Using Solid-Phase Microextraction and Syringe Headspace Sampling Techniques

“…Although it proved to be the most universal assembly for the isolation of compounds with diverse physico-chemical properties [81], Soleimani et al [77] demonstrated in their comparative study that phenolic monoterpenes and, more particularly, thymol, were better extracted by a simple polydimethylsiloxane (PDMS) fibre than using mixed coating materials. Furthermore, as the transfer rate of volatile agents toward the fibre increases with the incubation temperature of the sample [81], the temperature chosen could have potentially limited the extraction of thymol in our investigation. For example, in their research work, Nezhadali et al [82] compared the HS-SPME extraction efficiency of T. vulgaris EO main volatile agents at 25 • C and 50 • C using a water-based matrix.…”

Optimization of headspace solid phase microextraction for gas chromatography/mass spectrometry analysis of widely different volatility and polarity terpenoids in olibanum

“…Our study has been focused on the finding of the best experimental conditions to trap low volatile diterpenes on the SPME fiber. SPME was widely used for analysis of volatile organic compounds and especially terpenes in essential oils or in living flowers to elaborate perfume [8][9][10][11][12][13][14][15][16][17][18][19][20]. In this paper, we reported the best experimental conditions for trapping diterpenes from a gum resin.…”

Supercritical carbon dioxide extraction of cedarwood oil: a study of extraction parameters and oil characteristics

“…Solutions of CWO in hexane (ca. 200 ng/mL) were analysed by GC to determine the percentage contribution of individual components (Coleman and Lawrence, 1997). CWO extracts were analysed by 0.5 min split-delay splitless injection onto a Hewlett-Packard (HP; Santa Clarita, CA, USA) 5890 Series II GC equipped with a flame ionisation detector and an SP-2380 column (60 m  0.25 mm i.d.…”