This part works against anyone who sells essential oils, and we do sell them. It points out exactly where the most common testing method in the trade fails.
We write it for a simple reason: a seller who cannot pass the test they wrote themselves does not deserve to be trusted.
Four layers, ordered by how hard they are to detect
Layer one — dilution with carrier oil or alcohol. It leaves clear traces: the total of the characteristic components drops unusually, and with carrier oil a small drop on paper leaves an oil stain that does not evaporate after many hours. Alcohol leaves no stain, but shows itself in the beat of the smell during the first three seconds. This is the crudest layer and also the most common.
Layer two — filling with a cheaper essential oil from the same group. One step harder, because both ingredients are real essential oils. But the ratios between components drift out of the known range for the species, the marker components of the cheaper species rise, and the trace components of the real species thin out.
Layer three — adding pure components. Adding synthetic linalool to a weak lot of lavender to make the figures look good. An ordinary GC/MS analysis cannot detect this, because the synthetic molecule is structurally identical to the one extracted from the plant. The machine has no way of telling them apart.
Layer four — building it entirely from pure components. No routine analysis catches it.
What GC/MS really tells you
A gas chromatography–mass spectrometry analysis answers exactly one question: which compounds are in this sample, and in what proportions.
It does not say whether those compounds are natural or synthetic. It does not say how the sample smells. It does not say whether the product is safe.
That is already a great deal compared with a line on a label. But it is not everything, and anyone who sells it to you as a comprehensive guarantee is overstating.
Two tests that really can distinguish origin
Chiral chromatography reads the ratio between two optical isomers, which differs between the products of enzymes and the products of chemical reactions.
Carbon isotope ratios read the signature of the carbon source, distinguishing carbon from plants from carbon from petroleum.
Both are expensive, both need reference databases, and both are rarely used in routine testing.
How to use this information
Put the questions in the previous lesson to every supplier you intend to buy from.
How a seller answers — clearly or evasively, with sources or without, admitting what they do not know or not — is a fact about that seller, and it is often more reliable than anything printed on the label.