Testing Process

In Lesson 5, you’ll explore how essential oils are tested to ensure their purity, authenticity, and quality. At Aura Cacia, we combine sensory evaluation with advanced laboratory testing to confirm that every essential oil meets our rigorous standards.

This lesson explains how we use both our senses and science to detect adulteration, verify botanical identity, and maintain consistency from batch to batch. You’ll gain insight into testing methods, including the gold standard GC/MS testing, helping to protect the integrity of the oils you use and trust.

We begin by testing with our senses. Our well-trained staff has experienced hundreds of samples over the years, and they have developed precise standards for each component of our essential oils. Each new sample is tested against these standards to ensure its quality.

We look at the color, the mobility, and the volatility of the oil, and we smell the aroma. The most thorough way to do this is to assess the oil using a paper test strip. As the oil absorbs, it separates into top, middle, and base notes, which can each be detected individually. After the oil evaporates, it leaves a faint dry-out aroma that is also evaluated.

Optical rotation measures the direction and the degree to which light rays rotate left or right as they pass through an essential oil. The unique constituents in an oil influence the way that light is bent by the rotation of the electrons around its unique set of molecules. If the oil is authentic, the rotation will fall within a reliable range.

Gas chromatography separates the individual constituents of an essential oil and measures the amount of each constituent present. It confirms the oil’s botanical identity by comparing the presence and amount of each constituent. Chiral gas chromatography can screen for non-natural or missing constituents, or constituents occurring in unnaturally high or low ratios, signifying adulteration. Mass spectrometry specifically identifies each of the natural constituents in an essential oil by name and is able to pinpoint the presence and identity of any non-natural adulterants.

Specific gravity measures the weight of an essential oil. The molecular weights of all of the naturally occurring components of an essential oil combine to produce the standard and predictable molecular weight of the complete oil. Since every authentic essential oil is naturally made up of its own unique range of constituents, it should have a predictable specific gravity.

Refractive index measures the speed and angle at which a beam of polarized light is refracted when it passes through an essential oil, sort of like the way sunlight is refracted through rain to produce a rainbow. In the same way that the unique molecular properties of an essential oil can rotate light passing through it, they can also determine the degree to which a polarized ray of light is refracted. Each oil’s unique constituents predictably influence the speed and angle at which they refract polarized light.