Determining Essential Oil Purity


Before spending your hard-earned money on essential oils, you will want to know more about how to know if the essential oil is pure.

So, how does someone determine the quality of the essential oil? A quick search on Google for essential oils suppliers will show that costs for essential oils vary – ALOT! However, the price of an essential oil is only one factor to consider but not the only determining factor when shopping for quality oil. So, how can you decide which essential oil to purchase? Here are a few factors to help you determine the level of quality of the oil you intend to purchase.

Judging Essential Oils Quality Standards

It may surprise you to know the aromatherapy community is driven by politics. One such battle is in the area of essential oil quality and grading.

A set of chemical bottles with different contentYou will often see essential oils labeled as “therapeutic grade” or “certified pure therapeutic grade.” One essential oil company listed these four grades for classifying their essential oils:

Grade A – Essential oils are pure therapeutic quality and are usually made from organically grown plants distilled at the proper temperatures using steam distillation (i.e. Therapeutic grade).

Grade B – Essential oils are food grade, yet they may still contain synthetics, pesticides, fertilizers, chemical/synthetic extenders, or carrier oils (i.e. 100% Pure, but may be adulterated).

Grade C – Essential oils are perfume grade and may contain the same type of adulterating chemicals as food grade oils. These oils may contain solvents which are used to gain a higher yield of oil per harvest (i.e. Perfume grade).

Grade D – Floral Waters, which is a byproduct of the distillation process and of very high quality if it comes from Grade A distillation process. It is usually found in skin and hair products.


While standardization of grading essential oils such as this certainly would be useful for aromatherapy users (especially beginners), this one is only a sales tool orchestrated by a multi-level company as no such FDA-certified standards exist. In fact, the FDA only requires oil to contain 10% essential oil in order to be labeled, “100% Pure.”  Because the legislation would be an extremely complex and expensive endeavor, so far it has not been achieved. There are, however, two governing bodies that can lend guidance and some insight to the issue. Close up scientist hand with blue color glove try to open glass bottle

The Institute of Organizational Standards issued ISO standards, which is the closest thing you will find as a guideline. In France, where aromatherapy is arguably more cutting edge, a group called AFNOR (AFNOR is an acronym for Association of French Normalization Organization Regulation) issues guidelines stating the percentages of certain chemical constituents that must be present for an essential oil to be considered therapeutic grade. AFNOR’s considerations are slightly different as they do not have a direct interest in the holistic medicine industry, but more in the essential oil producer’s ability to trade on an equal footing in Europe.

Naomi Ball, Certified Aromatherapist and blogger states on her website, “most Lavender oils are fragrance grade and may be a high-quality grade oil for that purpose, but not necessarily therapeutic. To be therapeutic, there must be no traces of pesticides, herbicides, or other chemicals. It must be extracted by steam distillation and not by solvents. It must contain 25-38% linalool and 25-24% linalyl acetate and less than .05% Camphor.”

Although AFNOR and the ISO have monograph standards for certain plant extracts in different industries, they do not have standards for grades of essential oils. In fact, there are no current regulatory standards for the use of the descriptor “therapeutic grade” in the industry. Anyone can use the term to describe their essential oils regardless of their purity or potency.

Because of the absence of regulatory standards, some companies have added the terms “therapeutic grade” and “certified pure therapeutic grade” to their labels in hopes of gaining consumer confidence that their product has been developed with a higher standard of quality control and by labeling it as such represents their guarantee of being 100% pure. Note though, all quality essential oils will not necessarily label their products as such, so it will be necessary for you to become educated in knowing how to determine which essential oils come from pure aromatic extracts and those that may contain fillers and non-aromatic compounds.


Determining Essential Oil Purity

While it is true there are issues regarding the quality and grading of essential oils, this is not the only consideration. Essential oils can become adulterated or contaminated in many ways, rendering certain oils less effective and/or changing their properties. In some cases, this can also lead to irritation of the skin where another version of what would appear to have been the same oil may not have done so. For those who practice holistic medicine, it becomes crucial to find the best-unaltered product available that possesses the optimal ratio of natural constituents so that the synergistic effect between all the components within the plant remains intact and helps support the primary therapeutic function of the botanical.

In terms of judging essential oils quality standards, there are four key indicators: composition, oxidation, adulteration, and contamination. For instance, essential oils, which are derived from plants, go through a distillation process that could impact the quality of the essential oil. Or, the plants may be grown and harvested on a farm or come from “wildcraft” conditions, and factors such as soil condition and rainfall effect can impact the oil quality.



Identifying an essential oil’s chemical composition ensures its authenticity, quality, and purity. In a scientific analysis called Gas Chromatography and Mass Spectrometry, the individual constituents are separated and measured to confirm their botanical identity. Determining an Essential Oil's Purity | Aroma Hut Institute

These constituents are what contribute not only to its scent but also to its ability to heal. From plant to plant these will vary depending on many factors such as:

  • The altitude it was grown at
  • The amount of rainfall
  • The soil’s condition
  • The climate/temperature
  • The manner in which it was harvested
  • The way plants are stored prior to distillation
  • The length of time between harvesting and distillation
  • The type of equipment used for distilling
  • The storage of the essential oil

Therefore, while an essential oil may be pure, it may not necessarily be of the highest quality.

Special Note: Essential oils are never distilled from bananas, coconut, strawberries, blueberries, lilac, melons, ocean breezes, gardenia, linen, the beach, etc.  These are fragrance oils sometimes listed on craft supplies stores as essential oils.

Tip: Do buy therapeutic quality oils and not perfume oils. Perfume oils do not provide the therapeutic benefits of essential oils. Even if you only intend on using aromatherapy for the sheer enjoyment of the aroma, essential oils breathed in can offer healing benefits that perfume oils do not provide.



When the organic matter comes into contact with oxygen it inevitably starts a process of decay. It happens to everything, even to us, which is why every ad on TV regales foods that are powerful antioxidants. Antioxidants slow down the aging process and protect the body from free radicals.

Oxidation of essential oils happens at varying speeds, depending on the size of the molecules they are made from. Thinner oils, such as citruses, are prone to oxidation due to their high percentage of limonene, which lends in part to their sharp fresh scent. After oxidation begins, the percentage of limonene decreases causing the oil to become less effective. Other contributing factors such as light, heat, and oxygen can also affect the rate of oxidation. To prevent this, essential oils should be stored in sealed, dark, glass bottles to avoid heat and light.

Essential oils should be stored properly to avoid these elements from impacting their quality. Once a bottle has been opened and exposed to light, the process of oxidation begins. If you are fastidious, you should note what date you opened the bottle. Most practicing clinical aromatherapists will tell you they have oils in their medicine cabinets that are far older than their suggested shelf life date and believe they still have significant potency to them. When you consider many of the essential oils that were discovered during the archaeological digs of the Egyptian tombs that still held their medicinal properties, there is something to be said regarding cool, dark conditions that keep an oil’s properties intact for many thousands of years.


Things to Watch:

Essential oil descriptions should also contain the country of origin since the quality of the oil can vary from country to country. The use of pesticides or other chemicals can also impact the essential oil obtained. It is important to note that pesticides may also adulterate the essential oil if it is not eliminated in the manufacturing process. Adulteration becomes important if you plan on using the essential oil for therapeutic purposes. Even if you plan on using the oils as an air freshener, the aroma contains particles that enter your bloodstream u via inhalation.

Essential oils in the marketplace can be found in various dilutions or even marketed as perfume oils or aromatherapy oils. There are wide variations and taking the time to read the labels, product descriptions, and research your product will help to safely assess the quality of the oil. Perfume oils are not the same as essential oils and they do not share the therapeutic benefits that essential oils have. Aromatherapy oils may have already been blended with other oils or chemicals. Preservatives may have been added to protect and enhance the mixture.

There is nothing wrong with purchasing diluted, pre-mixed blends or perfume oils but just beware of what you are purchasing at what price. As you price shop at various stores online, you will find that many stores claim to sell essential oils, but in actuality, they are only selling a diluted version of the oil or the perfume oil. These oils are excellent for making soaps, creams, bath salts, and other beauty body products.

While there are no set standards for the shelf life of essential oils, most can be used within 1 – 2 years after opening. The oils should be stored in a dark bottle (amber glass or blue cobalt works nicely) and tightly sealed. Bottles with rubber stoppers should not be used to store the essential oil since the potency of the oil degrades the rubber and turns it into a gummy substance. The rubber can then fall into the oil thus contaminating the purity of the oil. Also, excessive exposure of the oil to the sun’s ultraviolet rays, heat, or air will degrade the oil. The oils should also be stored in a cool, dark place once you have them. A wooden craft box works nicely.

Be the informed buyer. Take the time to learn about what you are purchasing and then check if that fulfills your intended use. You will find that the quality of the essential oils can vary greatly and understanding what information is being provided to you will impact your purchasing decision.


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