Essential Oil Purity Guide

It all starts with raw materials

Essential oils are pure reflections of the botanicals from which they’re derived, but their production is an extremely complicated process with a multitude of variables, each of which has a significant impact on the quality of the final product. Raw material supply is one of the most important of these variables. Over the years NOW® Solutions has established long-standing relationships with many of our growers, which help us assure the quality and availability of the raw materials used for our essential oils. However, factors such as global market conditions and unanticipated weather events can affect the supply of certain oils from year-to-year and even season-to-season. As with many natural products, when supply is constrained there is concern regarding quality. Over the years we’ve seen examples of dilution, substitution, and even the use of synthetic alternatives masquerading as their natural counterparts.

So how does NOW Solutions consistently assure the identity and purity of our essential oils?

How do we protect retailers and consumers and ensure they’re getting the product they paid for? We utilize state-of-the-art testing and analysis as well as numerous checks and balances, including:

  • Identity and purity testing
  • Use of The Essential Oils compendium by Ernest Guenther, Ph.D. and Fenaroli’s Handbook of Flavor Ingredients, edited by George A. Burdock, Ph.D., to verify the correct essential oil species
  • Supplier/grower track record of providing high quality materials
  • Aroma comparisons
  • Review of essential oil processing to ensure that appropriate extraction methods are used
  • Appropriate cautionary and regulatory language

Because identity and purity are key attributes of any essential oil, testing for these attributes is the best way to ensure an oil’s quality. At NOW Solutions our identity and purity testing program consists of four individual tests.

Gas Chromatography-Mass Spec (GLC-MS) 

This sophisticated analytical technique utilizes specialized technology to separate an essential oil into its components for analysis. Our chemists take the results of the Mass Spectrometry analysis and compare them with a standard analysis for the specific oil being evaluated, carefully noting the presence and ratio of key identifying components and unique markers.  Components and markers not present will indicate oil from an incorrect species, and  components not normally present will generally indicate adulteration with other less expensive essential oils, fragrance compounds, plasticizers and the like.  NOW owns and operates several gas chromatographs, with an entire in-house laboratory devoted to this method of analysis.

Fourier Transform Infrared Spectroscopy (FTIR) 

Another sophisticated analytical technique we utilize is infrared spectroscopy. For this analysis, a sample is scanned with different Infra-Red frequencies which energizes the chemical bonds in the sample components causing them to vibrate. Every compound has a different vibrational pattern (called spectra) due to its distinct bonds, and this pattern serves as a “fingerprint” for the material being tested.  Each essential oil will also display a characteristic spectral pattern.  Highly trained chemists compare the spectra of the sample against standard spectra for that essential oil to ensure its identity.  Abnormal spectral patterns will indicate the presence of adulterants.  Although the two techniques are vastly different, when used together, gas chromatography-mass spectrometry and infrared spectroscopy provide incredibly powerful assurance of identity and purity.

Refractive Index

Refractive index is an analytical technique in which light is passed through a thin layer of sample sandwiched between two agate prisms. The degree to which the light is bent or “refracted” is measured and then compared to the value for the reference material, in this case the essential oil. Each essential oil will refract light differently due to their unique chemical composition, so the difference will indicate not only the identity of the substance but, more importantly, if the oil is pure. An essential oil that has been diluted with other substances would display an unacceptable variance in refractive index. Refractive index is another analytical technique used to confirm the identity and purity of the essential oil.

Specific Gravity

This relatively simple analytical technique compares the density of a material sample to a reference sample for the purpose of verifying identity. Certain types of adulteration will result in a unacceptable variance in specific gravity, allowing our technicians to further determine the identity and purity of an essential oil.

The combination of gas chromatography-mass spectrometry, infrared spectroscopy, refractive index, and specific gravity, and the ability to perform these sophisticated tests in-house and on-demand, provides NOW Solutions and our customers with powerful assurance of the identity and purity of our essential oils. These tests are performed on all of our essential oils.

Combining the results of all these techniques enables the chemist to achieve a complete characterization of the essential oil.

Therapeutic Grade

Therapeutic-grade essential oils are oils that a third party pharmacopeia or other statutory organization has (supposedly) created monographs for, which can be used by any brand as a measure of quality. We’ve reviewed the information regarding this grade and have concluded that “therapeutic grade” is just a marketing term used by some brands, with no authoritative body or organization behind the term.

Purity Guide (PDF)

Download the Purity Guide (PDF) we’ve provided. It has the most current examples of these tests for individual oils.† These tests are current as of the publication of this PDF (July 2014). However, our Quality Assurance Group will update these tests at regular intervals, or sooner if we begin working with a new grower/supplier, or when there’s a known issue with the supply of a specific oil. Current testing data for all of our products is maintained by our Quality Assurance Group.

At NOW Solutions we take assurance of the quality and purity of our essential oils very seriously. We’ve made long-term investments in the instrumentation and the professional staff necessary to assure the identity, purity and quality of our essential oils, and we work closely with our growers and suppliers to ensure the quality of our raw materials. By ensuring all aspects of essential oil quality we guarantee that what’s on the label is what our customers get in the bottle.

† NOW Solutions essential oil blends are produced with individual oils that have already been tested.