Scientific Testing of Essential Oils


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Gas Liquid Chromatography (GLC) Testing of Essential Oils

Gas Liquid Chromatography separates the various components of the essential oil. It produces a reading known as a chromatogram. Scientists are able to compare the reading of the particular oil with a “standard’” reading of what is expected for that particular oil.

Gas Liquid Chromatography testing works as follows:

  • The essential oil passes through a long tube which contains various stages of gas and liquid.

  • The essential oil then passes out of the tube and evaporates.

  • A trace of essential oil is recorded in a chromatogram reading.

  • Scientists compare the chromatogram reading of the essential oil with a standardized reading for that oil.

  • The readings will determine which essential oil components are present and if the essential oil is genuine.


Essential oils which contain lighter molecules pass through the tube faster than essential oils which contain heavy molecules. For example, citrus essential oils such as orange will pass through faster than an essential oil such as rose which contains heavy molecules.

High Quality Essential Oils

Scientific testing of essential oils establishes the individual chemical components which make up an essential oil and verifies the purity of an essential oil. It gives aromatherapists the knowledge and assurance that an essential oil has specific therapeutic properties based on previous research – without proper testing, aromatherapy can be, at best, little more than a pretty smell.


Carlos H.V. Fidelisa, Fabio Augustoa, Paulo T.B. Sampaiob, Pedro M. Krainovicb & Lauro E.S. Baratac. Chemical characterization of rosewood (Aniba rosaeodora Ducke) leaf essential oil by comprehensive two-dimensional gas chromatographycoupled with quadrupole mass spectrometry. (2012). Journal of Essential Oil Research. Accessed December 19, 2012.

Pavel M., Radulescu V., Ilies D.C., GC-MS Analysis of Essential Oil Obtained From the Species Thymus Comosus Heuff. Ex Griseb. (Lamiaceae)(2009). University of Medicine and Pharmacy, Bucharest, Romania. Accessed December 18, 2012

Daferera D.J., Ziogas B.N., Polissiou M.G., GC-MS Analysis of Essential Oils from Some Greek Aromatic Plants and Their Fungitoxicity on Penicillum digitatum. (2000). Journal of Agriculture and Food Chemistry ACS Publications. Accessed December 18, 2012

Clarke, S. Essential Chemistry for Aromatherapy. (2008). UK: Churchill Livingstone

Price, S., Price, L. Aromatherapy for Health Professionals. (2001). UK: Churchill Livingstone.

Schnaubelt, K., Advanced Aromatherapy: The Science of Essential Oil Therapy. (1998). USA: Healing Arts Press

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