Quality Essential Oils

Best practices to ensure you're sourcing the finest oils

Factors That Affect Quality

Just like wine, a number of factors affect the quality of an essential oil, including:

  • Where the plant was grown;
  • What part of the plant was used;
  • How it was grown;
  • What the climate was like;
  • How it was harvested;
  • When it was harvested;
  • How it was produced; and
  • How it was stored following production.

The quality of the finished product may be compromised if any one of these steps is not carried out optimally for that particular plant.

Buying Quality Oils

How can we ensure that the essential oils we buy are of a therapeutic quality suitable for clinical aromatherapy? Know your Supplier Start by developing a relationship with a supplier you can trust. Try to deal with suppliers either who distill their own material or who deal directly with reputable distillers. Suppliers usually will provide a small sample of the oil for you to check before purchasing larger quantities. Use Your Latin Names Order by the Latin name, and always check labels for the correct botanical name. Perform Your Own tests Make sure the oil is pure and not extended or diluted by using the organoleptic testing techniques we have learned so far. Educate your olfactory senses: Smell, taste, feel, and look at oils from many different samples and sources to gain experience.

Should you trust these sellers of locally sourced, organic Lavender Essential oils in France?

Do Not Rely On Price as an Indicator of Quality

Be aware that a higher price does not necessarily mean a higher quality. It is important to check all oils thoroughly regardless of the price. Note that a price that is very low compared may indicate that an oil is not as labeled, is diluted in a base oil, or is otherwise adulterated. Many expensive oils, such as rose and neroli, are sold diluted in a base oil such as sweet almond.

Gas Chromatographs

Gas chromatography (GC), mass spectrometry (MS), and similar additive-revealing techniques can analyze oils. This can be helpful particularly when purchasing large quantities. However, chemical analysis does not always reveal the presence of adulterants and an experienced technician must carry out the analysis of the MS. In addition, a GC must be conducted for each batch, so the cost can be very prohibitive for small distillers. A GC is not always a guarantee of quality. One test does not replace another. It is best to use all available tests in combination. Organoleptic testing is still the ultimate test.

Build Your Experience

The very best way to gain experience and familiarity with pure essential oils is to sample as many pure oils and synthetic oils as possible and document the differences.

Wildcrafted botanicals are desirable for therapeutic aromatherapy.

Wildcrafted Oils

Wildcrafted botanicals are desirable for therapeutic aromatherapy. A wildcrafted plant is commonly defined as: "Plants gathered in the wild, in their natural habitat, for manufacturing or personal use." Plants must be harvested at just the right time in their growth cycle and processed correctly to have optimal therapeutic action. Wildcrafting can create ecological issues: Wild habitats are being reduced drastically each day and a number of botanicals that have been traditionally wildcrafted are becoming endangered. Always check the status of a plant before you harvest to ensure that wild medicinal plants are preserved for future generations. United Plant Savers (http://unitedplantsavers.org) provides a list of endangered botanicals (the UPS "At-Risk" list) at their website.

Visit United Plant Savers for information on endangered plants before you harvest.

Be sure to purchase any wildcrafted essential oils from companies that follow ethical wildcrafting standards. In addition to ecological issues, industrial pollutants have contaminated many of our traditional international global sources. The Chernobyl nuclear disaster in 1986 contaminated a wide essential oil producing area of Eastern Europe. The destruction of forests in the Amazon, Central Africa, and throughout Europe and the United States, also contribute to the destruction of valuable healing plants and their potential essential oils. Unfortunately, the contamination of the earth continues into the new millennium.

Rosemary has confirmed and well defined chemotypes.


You may have heard the term chemotypes used in relation to essential oils and aromatherapy. What is a chemotype? First, it is important to understand that taxonomy is largely based on the phenotypical[1] morphology[2] of plants, rather than their chemical constituents. Thus, taxonomists group plants together into species based on their physical appearance, but they may have significantly different chemical characteristics. A chemotype is based on the chemical composition of a plant, rather than its physical appearance. A particular chemotype will produce an essential oil of a particular chemical composition that clearly distinguishes it from other plants within the same species. The basis of chemotypes is variation in chemical composition occurring within a genus. Chemotypes seem to be genetic adaptations, so this composition remains largely consistent for that particular plant irrespective of its growing conditions or locale. Thyme, rosemary, and basil are examples of plants that have well-established chemotypes.

Thyme, rosemary, and basil are examples of plants that have well-established chemotypes.

Rosmarinus officinalis is an effective example. The predominant chemical components are:

  • 1,8 cineole (also found in eucalyptus);
  • A ketone called camphor or borneone; and
  • An ester, bornyl acetate.

There are four main chemotypes:

The cineole type: Has an affinity for the respiratory system and is a more effective bactericidal. You will see this listed as Rosmarinus officinalis ct. cineol; The camphor type: Camphor in excessive doses may be hazardous to the liver and can cause convulsions if a dose above the RDD is taken internally. This is listed as Rosmarinus officinalis ct. camphor; The verbenone type: Listed as Rosmarinus officinalis ct. verbenone. Verbenone is a ketone so it may be hazardous as ketones can be abortifacient. Franchome and Penoel both list it as contra-indicated in pregnancy but do not mention the camphor and cineole types[3]; and The myrcene type: Myrcene is a monoterpene and a powerful analgesic. This is listed as Rosmarinus officinalis ct. myrcene. You can see the implications if these four quite different rosemary oils are bottled and labeled just as "rosemary oil".

Notes and References

[1] Encylopedia Brittanica defines a phenotype as: "All the observable characteristics of an organism, such as shape, size, color, and behavior, that result from the interaction of its genotype (total genetic makeup) with the environment. The phenotype may change throughout the life of an individual because of environmental changes and the changes associated with aging. Different environments can influence the development of inherited traits (e.g., size is affected by available food supply) and can alter expression by similar genotypes (e.g., twins brought up in dissimilar families may mature differently). Furthermore, not all inherited possibilities in the genotype are expressed in the phenotype, because some are the result of inactive, recessive, or inhibited genes." Source: Britannica.com. [2] The study of the structure of living things. [3] Price S & L, Aromatherapy for Health Professionals, 1999 pg 342

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