I was asked this question recently.
“Do you test every batch of your essential oils and if so, what do you test for?”
Here’s my response:
I do not test my own oils. I am not qualified nor do I have a money tree in the backyard to finance such endeavors. However, all of my oils are tested. Would you like to hear the truth about how many companies spin this information or outright lie to make it seem like they personally test all of their oils? Then read on…
The most common scientific testing is through a Gas Liquid Chromatograph (GLC) or GC (Gas Chromatograph). To keep the explanations simple, this equipment can provide a complex printout of all chemical constituents as well as levels of foreign matter, some pesticides, toxins etc., if it is calibrated to that level of sensitivity. Considering that essential oils can have 25 – 200 different naturally occurring chemical constituents, the results are very detailed.
The computer records each constituent as well as the levels present in the oils, and provides a report. The oils are then compared to other baseline tests and rated on acceptable levels. For example: The two main chemicals and their acceptable levels in tea-tree oil are: Terpinen-4-ol (35-40%), and 1,8-cineole ( 5 – 7%). This is an average established over many years for Australian ti-tree. The levels vary from year to year because of growing conditions, hence the general range allowed.
To be very thorough, a MS (Mass Spectrometry) provides detailed data on the individual components identified by the chromatograph. This is the stage where individual constituents can be evaluated for synthetic tampering. These are basic tests performed on essential oils. There is no “selective testing” for certain elements or pesticides. A test is basic and standard.
A basic GC test can cost $300 -500, while the MS can cost a further $300 or more for one sample, and must be signed by a chemist with a documented expertise in essential oil analysis for authentication. To make the test unbiased, it should be done with a controlled sample via independent lab. There are only a handful of labs in North America that have the ability and credentials to test essential oils with expert chemists on staff. They usually have a huge waiting list of clients and oils to be tested as a result. It can take months to have tests arranged.
As a purchaser of essential oils, this cost alone for each batch could be prohibitive and accumulates to a massive expense for a small business, not to mention the logistics of arranging tests. Even if there is proper documented testing with batches of oils, it means nothing of the oil supply is not handled and stored correctly. Even tested great quality oils can become old and oxidized relatively fast.
There are other tests which should accompany direct purchases from essential oil brokers, distillers and other producers. This information is contained on a Certificate of Analysis. A Certificate of Origin should be attached as well for NAFTA purposes. I receive these with all of my shipments. Without the benefit of a full GC test, it still provides valuable information to someone who is trained to evaluate the results and has more reassurance that the oil is from a direct source and not tampered or adulterated. Key information contained on a C of A includes:
Specific Gravity This test measures the weight of a substance in relation to water. The weight of water is considered 1. Since most essential oils are lighter than water, their specific gravity will be less than 1. The results of each test are then compared with standard weights for each oil. If an essential oil is significantly higher or lower in weight than average, it raises suspicion as to the overall purity and can indicate adulteration. A proper test is conducted at 20 & 25 C
Refractive Index: The refractive index of an essential oil designates how the oil responds and bends light, measuring how the speed of light is altered when passing through the oil. An oil’s refractive index can be compared to that of a standard result. Usually conducted at 20C
Optical Rotation: To determine the rotation of polarized light through a liquid to establish its optical activity whether dextro (bends light to the right) or levo (bends light to the left). The degree of rotation and its direction are important as a criteria of purity and whether adulteration has occurred.
Appearance, Colour and Aroma should also be documented and conform to basic standards.
There is an interesting trend lately with some of the bigger essential oil companies claiming to have on site GC equipment to test oils. Pharmaceutical companies and some reputable essential oil companies do this but to satisfy some of their own requirements for specialty purchasing and do not boast about this being an integral part of testing their oils for the public.
I don’t place a lot of value on this with most essential oil companies because this equipment can be purchased second hand at a relatively inexpensive price. People with not a sliver of essential oil or chemistry knowledge can run a test. As a result this doesn’t mean very much as it will be biased, with undocumented control samples, lack of calibration and expert analysis.
But hey, “they can say that they test all of their oils…”
Most essential oil producers and distillers will have tests done on batches and make the results available for purchase at a nominal price to offset cost or sometimes offer with shipments, but this is usually reserved for the purchase of large quantities in drums at wholesale levels. Most start-up companies reselling essential oils can’t begin to come close to the purchasing quantities necessary to obtain this information. I know, I’ve been there.
So, to summarize, I don’t test all of my oils and I don’t believe most companies who sell a variety of essential oils do either. It would price us all right out of the market. They likely purchase or obtain tests done with originating producers. There is nothing wrong with this unless they twist this information to look better. Yes their oils are tested, just not by them. Testing of essential oils drives the price high enough without trying to shoulder the cost of testing them again.
To companies who make this claim I specifically ask, “Do you directly incur the cost to test all of your oils at your own expense using independently qualified labs utilizing full GC and MS analysis?” If they say “Yes“ there is no way to verify except to go to their company, match the lot # on the drum to the paperwork and watch it being poured. I don’t know of any company which would allow this. Some companies keep reissuing the same paperwork over and over, just changing the batch # and the date.
I do have valid independent tests for most of my oils along with my 23 years of experience working with thousands of kilos and varieties of oils from all over the world in clinical, therapeutic and product formulation. I have been to some of the growers, watched distillation, read hundreds of GC and C of A reports. This is just as valuable as having oils tested with sophisticated equipment, and frankly, I would rather deal with experienced brokers and producers who provide some testing and experience which further helps to educate me.
If they say “No” when asked whether they test all of their own oils, at least they are being honest.