How to check the quality of an essential oil? Is it within anyone's reach or do you need a masters in organic chemistry?

From the point of view of an aromatherapy expert or a merchant, the knowledge to be accumulated in order to master the quality of these products must be both specific and vast. But from the point of view of a user of essential oils, it is entirely possible to sort things out, to separate the good bottles from the mediocre, or even the bad. This is the objective of this guide: to make you autonomous in the critical analysis of the quality of an essential oil.

Essential oils are natural products, with powerful therapeutic virtues and generally a high market value. The offer available on the essential oils market is therefore very diverse in terms of quality, for 3 main reasons:

• The first is that nature is not a factory : it is not capable of producing the same standard product twice. Each plant is a living organism whose fruit will depend on the genetics of the plant, its growing conditions, the weather, the soil that nourishes it, etc. For essential oils, this natural variation in quality  is increased by the fact that we use a concentrated extract of the active ingredients of the plant. It goes without saying that this concentration further accentuates the natural variability of each plant. Through the sole intervention of nature, batches of essential oils bearing the same name are often of very different quality, even from the same plantation. Of course, this difference is greatly accentuated when the biotopes are not the same.
• The second cause of this great diversity of qualities is fraud . Essential oils are particularly affected by this risk of fraud: they are expensive and sometimes come from the other side of the planet, with many intermediaries. Cases of fraud are legion, and often go unnoticed until the end consumer. This can involve dilution with simple raw materials (water, alcohol, fatty substances, etc.), mixing with a similar and less expensive essential oil, modifying the essential oil by adding synthetic compounds or by physical processes, etc.  The imagination of fraudsters can go very far, and the impact of fraud is far from negligible on the average quality of essential oils.
• Finally, the third and final cause is the diversity of ways of using essential oils. Indeed, essential oils are aimed at a very varied panel of consumers, with very different quality expectations. At the top of expectations is aromatherapy, then comes DIY cosmetics, use in room diffusion, and individual use for household products. This diversity of expectations in fact maintains a diversity of qualities available on the market.

The subject of essential oil quality is therefore a very critical subject. It is not about nitpicking, but about real impact factors. The objective of this article is to help you find your way if you are looking for 100% natural, pure and therapeutic quality essential oils 

Chemotype is a word commonly used in aromatherapy jargon, but its interpretation varies, and continues to evolve depending on the professionalization of the sector. Originally, this word designated the necessary distinction that had to be made between a Thyme with Thujanol for example, and a Thyme with Thymol, and this distinction therefore only concerned a few species: thymes, rosemaries, lavenders, etc.

Today, when we talk about a chemotyped essential oil, we are talking about an essential oil whose following 3 components are known to the manufacturer and specified on the label:

• The precise botanical definition , in Latin therefore, includes genus, species and subspecies or variety (if applicable). For example, for a Verbenone Rosemary:  Rosmarinus officinalis L. verbenoniferum , which does not have the same properties at all as a Cineole Rosemary:  Rosmarinus officinalis L. cineoliferum. In France, it has become very rare, fortunately, to find essential oils that do not make this distinction. Beware, however, of certain major American brands that are as expensive as they are of poor quality.
• The main molecules found in this essential oil. This is a short list containing the few main molecules of this chemotype, without details on the expected concentrations. A Ravintsara for example, should mention the composition in 1,8 cineole , in sabinene , in alpha terpineol .
• The origin of the plant and therefore of its essential oil . This is a critical piece of information that is often missing, and which can have a considerable impact on the price of the essential oil. However, it is essential to guarantee a chemotype, and clearly and precisely completes the list of molecules. An essential oil of Nepalese Matricaria Chamomile, for example, will indeed contain alpha bisabolol , but only 5% instead of 35% in a Hungarian Matricaria Chamomile.

A chemotyped essential oil is therefore an essential oil defined, even on the label, on these 3 criteria: botany (precisely) + composition (approximately) + origin (precisely). If you want to benefit from therapeutic virtues via essential oils, orally or cutaneously, the use of chemotyped essential oils is essential , for reasons of effectiveness, but also safety. So check your bottles carefully,  and greatly favor brands indicating the origin of the batch sold.

Your essential oil is chemotyped: this is already very good, and rather rare. If you use this essential oil to purify the air in your home with a diffuser, or for a DIY cosmetic cream recipe, it is sufficient quality. If you are expecting therapeutic use, you are almost there. You still have to check the transparency of the brand concerning the analyses it does for each batch.

Why is this important?

• This assures you that the brand has a solid control plan . Today, fraud cannot be avoided with simple intuitions or random checks. Each batch must be tested, at least to verify the composition of the essential oil and its few basic physical components (density, refractive index, etc.). For the most risky essential oils, additional tests must be planned.
• This assures you that the choice of its chemotype is relevant or that it has been worked on , that it is not motivated by pecuniary interests, but by precise specifications, corroborated by public analyses. The composition of essential oils is also specified in most aromatherapy books. This allows users to compare with that put forward by the brand, and verify that it is indeed the chemotype sought.  For example, an essential oil of Italian Helichrysum from the Balkans can be quite chemotyped... but this chemotype is not the right one if we want to benefit from the properties recognized in aromatherapy books for Italian Helichrysum.
• And finally, it encourages the brand to maintain its consistency with regard to the quality announced. Claiming to sell the best essential oils is one thing, voluntarily publishing its analyses, at the risk of having to be held accountable, is another.

What analysis are we taking about?

Within the framework given above, the following analyses should be carried out and analyzed for each batch of essential oil , in order to reject those which do not meet expectations.

• The most important of these is the chromatographic analysis . This is an analysis that allows us to know precisely the composition of the essential oil: which molecules, and in what quantity? This analysis and its interpretation must be the heart of any quality approach in aromatherapy.
• Next comes the control of the organoleptic characteristics . Each essential oil has a unique color, odor and appearance, identifiable among other essential oils, even those from the same plant family. Sometimes, this control allows to detect failing qualities that chromatography would not have seen.
• And finally, the analysis of certain physical data such as density, refractive index and optical rotation, which again allow certain lots to be excluded.

Of course, the established control plan should not be reduced to these analyses, but in terms of systematic analyses, batch by batch, we have a sufficient basis here.

How do we check?

• The physical and chemical specifications of the essential oil, its specifications so to speak, must be public (website, technical sheets, etc.).
• A batch number must be mentioned on the bottle.
• On the brand's website, the batch analysis results must be available. It is therefore possible to compare them with the specifications put forward.

As there is no certification body for this quality requirement, the brand's voluntary transparency on its specifications and the tests it carries out for each product is decisive in the trust you can place in it.

To recap: to ensure the therapeutic quality of an essential oil, it is therefore above all necessary that its chemotype be specified and verified, and finally and above all that the results of its analyses be accessible.