oils-standardization-qualityTo receive all the benefits of essential oils, they must be of high quality. In this blog, I continue the topic of determining the quality of essential oils.


Essential oils are precious and the power of these secondary metabolites can be altered by production, manufacturing, and distribution. (1) (2) In Part I of this series, I discussed several factors to consider when determining the quality of essential oils. In Part II, I dive deeper into this topic and review specific tests that can be used to analyze purity. I also describe the research I did to choose a company that I can comfortably, ethically, and authentically recommend. Finally, I “pepper” in some research updates that fit in with this discussion. These snippets expand on quality and provide some more references from my talk on the Healthy Gut Thinner You Summit. (Fun fact: pepper oil may help nicotine cravings and that certainly also makes for a healthier gut!) (3) (4)


Essential Oils Versus Fragrances

How do you know your essential oil is the “real deal” and that you are getting the intended actions, not unwanted side-effects? Although some chemists may not acknowledge that essential oils produce different effects beyond the stimulation of odors, many are aware that this is scientifically documented and, therefore, insist on using pure essential oils. (5) (6) Furthermore, synthetic fragrances can be downright harmful in how they are isolated and produced! (7) (8) (9) (10) Therefore it’s important to make sure your essential oils are not cut with harmful synthetics, fillers, or adulterants and not just standardized to a specific compound. In this way, you are not only avoiding “toxic beauty” but also assisting and supporting your body’s systems.


My Search

When I first started out with essential oils, I cross-referenced the company my mom was using. I was very weary of her “hippie herbs” and “plant juices.”  Wanting to see if some “internet hype” was founded, I discovered the First International Symposium on Integrated Medical Aromatherapy in Grasse, France (March 21-22, 1998). (11) There were some impressive and esteemed essential oil experts including Pierre Franchomme, director of research, Bucharest, Romania, and Daniel Penoel, M.D. (12) I also was able to obtain some certificates of analysis, at that time printed in a textbook, and visit an essential oil supplier’s farm (which I’ve since recently returned to).

While I was doing some digging for this blog, I also found an abstract submitted in the 2016 International Symposium of Essential Oils (pg 63*) and several in the sponsoring peer-reviewed journal (a). These are articles in various other journals (b, c, d).


More Research on Quality

Finding this abstract sent me down a bit of a rabbit-hole exploring some of the science. There were so many goodies that I had to make time to read and skim through all the 183 pages!

Here are some highlights on topics relating to quality found among this research gem:

  • The complexity of determining quality using gas chromatography (a, pg 31)
  • Differing quantities of components in peppermint oil by plant location in Algeria (a, pg 55)
  • Volatile contaminants found in essential oils from manufacturing (a, pg 59)
  • Benzene contamination in fragrances (a, pg 77) and 82 compounds found as contact allergens (pg 152)
  • Chemical composition variation with season (a, pg 101), cropping type (a, pg 146), and climate (a, pg 144)
  • Effects of topsoil on components of essential oils (pg 153)

I explore some other topics, besides quality, here.

*Pages are based on PDF numbering

*Please review the abstracts and articles for specific brands and methods on oils used in studies to determine quality control. Not all studies use the same brand of oils or methods to distill their own. This can result in differences in outcomes.


Quality Control from Start to Finish








Therefore, besides analyzing the final product, you would want to consider the method of oil production. This includes:

Raw materials (is the oil sourced from seeds that are organic on pristine soils)

Cultivation practices (and are they sustainable?)

Monitoring distillation time, temperature, pressure, and specs:

  • For example, Lavender has differing amounts of chemical constituents based on distillation time. (13)
  • Using shortcuts for distillation may speed up the process, but it can result in suboptimal oils. In this case, manufactures may add fillers and synthetics to make the product more convincing as “lavender.”


Verification Testing:

Due to the complexity of essential oils, it’s important to use more than one verification test. Here are some examples:

  • GC/MS (Gas chromatography (GC)- used to separate mixtures into individual components using a temperature-controlled capillary column
  • Mass spectrometry (MS)- used to identify the various components from their mass spectra. (14)
  • Flash Point– the lowest temperature at which vapors of a fluid will ignite
  • Optical Rotation– the angle by which the plane of linear polarized light is rotated when passing through the sample, a measure of purity and chirality (15)
  • Refractive Index– a dimensionless number that describes how light propagates through that medium
  • Specific Gravity– the ratio of the density of a substance to the density of a reference substance
  • Fourier transform infrared spectroscopy– represents the molecular absorption and transmission, creating a molecular fingerprint of the sample.

Tests for contamination:

  • Heavy metals analysis (which aren’t usually distilled)
  • Microbial contamination


Finally, each essential oil should be carefully bottled and labeled using state-of-the-art equipment.

Essential oils safe for consumption are labeled as such (see GRAS list here).


Hopefully, this information will help you see the science and art of making pure essential oils. It also demonstrates the complexity for the consumer. You know my favorite and it’s important for you to make sure your favorite is up to quality standards as well.


Happy oiling!


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This material is for information purposes only and is not intended to diagnose, treat, or prescribe for any illness. You should check with your doctor regarding implementing any new strategies into your wellness regime. These statements have not been evaluated by the FDA.