The best way to assure the purity and quality of each batch of oil is with GC/MS testing. (Gas Chromatography/Mass Spectrometry.)
The precise breakdown of the chemical components in individual oils is important, because the therapeutic benefits and safety issues of essential oils are in large part determined by their chemical makeup. GC/MS testing is also used to identify any adulteration of the essential oil tested.
Samples of all oils at Aromatics International are tested. Once an essential oil is tested, the GC/MS reports are posted on the Aromatics International website--free for anyone to use and print. All the main components--and some of the trace components--are listed on these reports. Aromatics International’s GC/MS reports are kept updated, and the old reports are archived for research and review. You can see each essential oil’s GC/MS report by visiting the essential oil’s page and clicking on the GC/MS report at the top or bottom of the page.
Any reputable supplier of essential oils is dedicated to knowing exactly what they are buying and selling.
Every batch of oil I purchase from a distiller is tested with GC/MS. Testing every batch of oil with GC/MS technology assures purity and provides the exact chemistry for the specific oil tested. This information is vital for effective medicinal blending and for quality assurance.
GC/MS testing cost about $75 per oil, and tests are the responsibility of the supplier. Distillers do not always complete these tests, and the tests are too expensive for an individual to afford. However, for a supplier or essential oil company, this is a low cost that applies to the entire batch purchased. It is becoming industry standard for aromatherapy companies to provide these test results, and they are vital tools for true medicinal blending.
An interesting note is that the country of origin can affect the chemical makeup of an essential oil. Helichrysum is a good example. Helichrysum from Corsica has a large percentage of specific esters. These esters have a strong antispasmodic effect. Helichrysum from Croatia has almost no esters and is high in sesquiterpenes and ketones—known for healing damaged skin. Each Helichrysum is unique. We can only know exactly what’s in it with GC/MS testing. Once the analysis is completed, we can look at the report and know more clearly what the best therapeutic uses of that oil will be.
Some plants have the genetic ability to produce different chemical constituents based on the environment they grow in. This is called a "chemotype." One example is Rosemary. Depending of the country of origin and the growing conditions, Rosemary can produce very different essential oils. The oils vary so dramatically, their primary chemical families change. This is important, as different chemotypes are used for different medicinal purposes, and have different safety concerns.
Being able to identify the specific “chemotype” of an oil is also important. This can easily be done through GC/MS.
When shopping for essential oils, always look for current GC/MS reports. Whether you're blending medicinally or not, it's important to know that you're purchasing quality, unadulterated oils. Remember that fragrance oils and synthetics can cause a myriad of problems, from headaches to allergic reactions. If you're not sure if the company you're purchasing from performs full GC/MS reports, simply call or email their customer service.