Purity & Quality

Essential oils are not only distilled and used for the purposes of aromatherapy, they are also more commonly used in the personal fragrancing, home fragrancing, cosmeceutical, food/beverage and other industries.


The standards for essential oil quality and purity are highest for aromatherapy use. The purity and quality of essential oils affects their therapeutic value, aroma, color and flavor when applicable for the food and beverage industries*. The higher the quality of a particular distillation of oil, often the higher the price the oil commands. Because essential oils with particular characteristics command significantly higher prices, there is a large temptation for distillers and suppliers to adulterate (alter) essential oils.


Aspects of an essential oil's purity and quality can be quantifiably tested. Some aspects of an oil's quality, namely on an olfactory level, however, is a more subjective process.


*Essential oils are used in the food and beverage industries under careful control and extremely low concentrations, in formulas/recipes usually created by highly knowledgeable formulators. Essential oils should NOT be taken internally by those not well educated in doing so.


Why Is the Quality/Purity of an Essential Oil Important?


Those practicing holistic medicine focus upon using complete, unaltered essential oils and herbs. The belief is that by using the complete botanical, there is a synergistic effect between all the components within the plant that help support the primary therapeutic functions of the botanical. For example, one of the side effects of using pure "unbuffered" aspirin is that it can severely upset the stomach and can even promote stomach ulcers. Using large doses of White Willow Bark, an herb that contains the active components that give aspirin its ability relieve pain, can certainly cause the same complications, but White Willow Bark is more gentle when used moderately in its whole state.

If you are over 30, you probably recall that there were far fewer people with asthma and allergies when you were growing up then there are today. And far fewer people with skin conditions such as psoriasis and eczema. My personal belief is that the growing number of individuals with these conditions is directly related to the increased use of medications, processed foods and skin care products containing synthetics.


There is a lot to be said for focusing upon consuming and using natural ingredients including pure essential oils that have not been blended with synthetics. Essential oils that have been adulterated or tampered are no longer pure, whole, natural substances.

Aren't Most Essential Oils Pure?

Pure, unadulterated essential oils that possess the optimum ratio of natural constituents for therapeutic benefit are sought for therapeutic use in aromatherapy.

Essential oils, however, are distilled and used not only in holistic aromatherapy, but as mentioned previously, are also distilled for use in the personal fragrancing, home fragrancing, cosmeceutical and in the food/beverage/flavoring industries. In these industries where purchasers of essential oils use them for mass production, there is far less need for "pure" essential oils and far greater need for consistent, standardized essential oils that do not change from shipment to shipment.


For example, is used primarily as a flavoring for candies (i.e. Candy Canes), chewing gum and ice creams. It is often referred Peppermint Essential Oil to on food ingredient labels as Oil of Peppermint or simply as Peppermint Oil.Because large food/candy manufacturers must produce a consistently flavored product, the intensity, aroma and overall flavor of the peppermint oil they use must remain consistent between each lot of oil that they purchase. Peppermint Oil manufacturers/distributors, therefore typically standardize the essential oils that they sell by establishing a blueprint of the percentage that each important constituent should reach within each essential oil. They then test the oil and then adjust the oil by adding or removing constituents until the resulting oil meets the ideal percentage.


This standardization process, however, is not ideal for aromatherapy work as the resulting oil is no longer a natural unadulterated distillation or extraction and may contain added synthetic constituents or may have important constituents removed.


Standardized oils are not always clearly marked as such. Additionally, some essential oils are tampered with, also known as adulterated, in order to give the illusion that the oil is of an higher quality than it is, or to extend more costly oils in order to make more money on the sale of the oil. For example, the pricy Japanese citrus Yuzu Essential Oil resembles a combination of grapefruit and mandarin essential oils. Some sellers may be tempted to blend grapefruit and mandarin essential oils together and market the blend as the more expensive Yuzu Essential Oil. Patchouli Essential Oil is sometimes extended with the addition of less costly balsams or cedarwood. Lavender Essential Oil is sometimes adulterated by the addition of more linalyl acetate.


Constituents - What Do Essential Oils Consist Of?


All substances can be broken down into an array of molecules and atoms, and essential oils are no different. Each essential oil can be broken down into an array of different natural chemical constituents.


Many of our modern medicines are a result of analyzing the natural chemical constituents of raw botanicals and distilled essential oils. Common aspirin is one example. White Willow Bark, used over 2,000 years ago by Hippocrates to ease headaches and other muscular pains, contains a natural anti-inflammatory identified in the nineteenth century as salicin. Salicin is a cousin to salicylic/acetylsalicylic acid, more commonly known as aspirin. White Willow Bark is still routinely used by herbalists to more naturally relieve pain and inflammation.


After the analysis and discovery of the benefits of the effective components in essential oils or raw botanicals, chemists routinely isolate these constituents for use in modern medicines. Chemists then derive ways to more inexpensively synthesize these constituents.

The constituents that make up any given essential oil includes chemicals classified into the following groups

(this is not a complete list):

                                                                                                                 Acids, Alcohols, Aldehydes, Coumarin, Esther, Ester, Ketone, Lactone, Oxid,  Phenols, & Terpenes

Lavender Oil, as one example, contains a high percentage of the ester known as linalyl acetate. Because of science's ability to isolate and synthesize particular constituents, we must be careful within the practice of aromatherapy to ensure that the essential oils that we use haven't been adultered with isolated or synthetic compounds.


Quality vs. Purity - Aren't They the Same Thing?


An oil can be pure while simultaneously being of poor quality. By holistic aromatherapy standards, an oil that is not pure is clearly considered of poor quality.


What Affects the Quality of Essential Oils?


The aroma and exact percentage of each natural constituent contained in a particular pure, unadulterated essential oil can very depending on a variety of factors:


• Quality of the soil the botanical is grown in

• The amount of rainfall

• The temperature/climate

• The altitude

• The way the botanical is harvested

• The way the botanical is stored prior to distillation

• The length of time that passes between when the botanical was harvested and when it is distilled into an essential oil

• The exact part of the plant used in the distillation of the oil

• The type of distillation equipment being used including the material it is made out of (i.e. copper vs. steel components)

• The storage conditions of the essential oil

• Any adulteration/tampering with the essential oil


What Affects the Purity of Essential Oils? How are Essential Oils Usually Adulterated?


An adulterated essential oil is one that has been tampered with in some way. The common ways that essential oils are adulterated are as follows:


• Blending/combining other less expensive essential oils and fraudulently marketing the oil as a pure, more costly oil. (i.e. the Yuzu essential oil example mentioned previously

• Blending a higher quality essential oil with a lower quality version of the same species

• Adding individual constituents, whether naturally or synthetically derived, to an essential oil

• Adding synthetics to improve the aroma

• Adding vegetable (carrier) oils and not disclosing the dilution to the end consumer (This can be easily detected by the consumer by simply placing several drops of the oil on a tissue or perfumery blotter and waiting for the oil to dry out. If an oily ring remains, the essential oil has been diluted in a vegetable oils.


Quantifiable Testing of Essential Oils for Quality and Purity


Several quantifiable tests exist that allow scientists, producers, suppliers and end users to be able to test their oils to determine quality and help to ascertain if an oil is pure and of the quality sought after for each particular botanical.


Gas Chromatography and Mass Spectroscopy (GC-MS)


Testing by means of Gas Chromatography and Mass Spectroscopy can help to verify that the constituents contained within an essential oil sample are representative of what that particular essential oil should contain.

Gas Chromatography and Mass Spectroscopy are two separate tests that are usually both conducted on an oil specimen to identify constituents contained within it. Mass Spectrometry assists in identification of the specific constituents measured within Gas Chromatography, so typically, both tests are done together.


Gas Chromatography


Gas Chromatography, also known as Gas Liquid Chromatography is abbreviated as GC or sometimes GLC.

Gas Chromatography measures the constituents contained within a particular essential oil sample by plotting each constituent found within the sample onto a graph. To begin, a sample of the oil is placed into the heating chamber of the gas chromatograph machine. The oil sample is then heated to a specific temperature until the constituents vaporize. Each constituent vaporizes at a different rate of time. As each constituent vaporizes, is passes through a detector that measures a) the time it took for the constituent to vaporize and b) the percentage/concentration of the constituent within the particular sample.

The gas chromatograph machine plots a graph of the results. The x-axis identifies the time that passes between the vaporization of each constituent. The y-axis shows the percentage concentrations of each constituent within the oil.


Mass Spectrometry


Mass Spectrometry, abbreviated as MS is often used in conjunction with Gas Chromatography as it can aid in determining if a sample contains any adulterants.

Each compound, after passing through the gas chromatograph machine, is fed into the mass spectrometer. The Mass Spectrometer ionizes the compounds, sorts each by their mass-to-charge ratio and then measures their molecular weights. The results are then charted.


GC-MS Test Results - How Can They Be Used?


The data collected by way of the combined GC-MS test can be used to compare the specific constituents and their percentages to those of a known sample that possesses reliable purity and is of the optimal quality for the specific botanical.


The results are used in a multitude of ways including the following:


• Unusual levels of particular constituents in the tested oil can flag that the oil is of inferior quality or has been adulterated. These results can act as a forewarning to suppliers, retailers and manufacturers.

• Distillers, who of course already know whether the oil they are testing is pure or not, often test their oils to compare with previous distillations to compare quality between harvests and distillations.

• If the GC-MS results determine that the oil contains an unsuitable level of certain constituents, distillers/producers may adulterate the oil so that the oil appears to be of higher quality.

• Suppliers and large end users often test their oils to ensure purity and quality.

• Manufacturers in other industries such as in the personal fragrancing and food/beverage industries where purity is not a concern use the results to identify whether the levels of key constituents are suitable and if not, to potentially alter the oil until the constituent ratios are satisfactory.


Other Quantifiable Tests for Testing the Quality and Purity of Essential Oils


Other tests may be used upon an essential oils. The most commonly used tests after Gas Chromatography and Mass Spectrometry are Refractive Index and Specific Gravity. The results of these tests are sometimes provided upon the oil's MSDS (Material Safety Data Sheet).


Refractive Index


Measured by a refractrometer, the refractive index of an essential oil is a unique number that designates how the oil responds and bends light. Essentially, it is a measurement that tests how the speed of light is altered when passing through the oil. An oil's refractive index can be compared to that of a reliable sample.


Specific Gravity


Measured using a densitometer, the specific gravity of an essential oil is a unique number that measures the density of a particular oil in comparison with the density of water. Specific gravity readings are measured at precise temperatures and pressures as temperature and pressure can impact the measurements. Particular oils have known ranges of specific gravity in which the oil is considered to be unadulterated and pure. Of course, an essential oil distilled from an inferior harvest or improperly distilled can also lead to specific gravity readings outside the norm.


Other possible tests that may be conducted upon essential oils include the following:


• Optical Rotation

• Acid Value

• Infrared Spectroscopy


Essential Oil Quality and Purity Conclusion: Final Questions & Answers


Are the Tests Foolproof?


GC/MS and the other tests are not foolproof because most retailers and end consumers do not have the equipment or the scientific knowledge to be able read/scrutinize the testing. Testing does risk falsification and also depends on the qualifications, moral standards and knowledge of those performing the tests. Most mid-level suppliers and retailers cannot afford the equipment or training to perform their own testing. Retailers often must trust on the GC/MS and other testing figures provided by their suppliers. Some retailers do go to the expense of having a third party testing facility test the oils that they sell to insure that their supplier is not falsifying GC/MS documents and are providing pure oils, but this added testing is costly and will be integrated into the final cost of the oils they sell.


Some aromatherapists and manufacturers, have oils that they purchase tested by a third party to ensure that the retailers/suppliers that they purchase from are truly supplying unadulterated oils. It goes without saying that when aromatherapists and end users discover deceipt on the end of a retailer/supplier, that supplier's reputation will most likely suffer.


Why Don't All Suppliers Perform Their Own In-House Testing?


As mentioned in the "Are the Tests Foolproof?" section, the cost for the testing equipment is expensive, and the ability to utilize the equipment and understand the readings requires specialized training. Some suppliers/retailers do outsource testing on all of their oils. This outsourced testing, however, can become quite costly if a retailer has each lot that they purchase tested (i.e. when they repurchase another lot of the oil when their inventory depletes). To reduce testing costs, some suppliers/retailers perform initial outsourced testing when they find a new supplier and then randomly at periods thereafter to insure that the supplier/distiller's quality/ethics hasn't changed. Some retailers/suppliers rely strictly on the testing performed by the distiller/supplier/manufacturer.


Can I Depend on Companies that State That Their Essential Oils are "Therapeutic Grade" or "Aromatherapy Grade?"


There is no governmental regulating body that grades or certifies essential oils as "therapeutic grade" or "aromatherapy grade." Not all companies use these terms with deception in mind, but consumers do need to be precautious.


How Can Consumers Ensure Purity?


Without the ability and knowledge to directly perform or oversee testing ourselves, we as consumers are in a buyer's beware situation and must hold a great deal of trust in those that we purchase our oils from. In addition to issues of purity, the quality of an essential oil can also be impacted by how a retailer/supplier repackages and stores their oils, and the freshness (how long has that oil been sitting on the shelf?) of the oil. Although a level of "buyer beware" does exist for the average consumer, the risk can be greatly diminished by purchasing your oils from sources that you know have been selling essential oils for at least several years, that cater to the aromatherapy industry, have a good, solid reputation in the industry, and that you know or suspect sell directly to aromatherapists and other aromatherapy professionals. As touched on above, those suppliers that sell adulterated oils will, in time, be "found out" and their reputation will certainly be exposed.


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