What the words on the label are worth, the documented ways an oil stops being what it says it is, and the checks you can run before you trust a bottle.
~11 min read
Somebody hands you a small amber bottle. The label says 100% pure; underneath, therapeutic grade. Both phrases were written by the person selling it, neither was checked by anybody, and there is no office you could ring to ask.
This is the plain regulatory position, not a scandal. In most markets essential oils are sold as cosmetics, flavourings or household goods, and none of those categories carries a grading system for aromatic plant extracts. There is no legal definition of the word pure as it is used on a bottle. “Therapeutic grade” sounds like a classification handed down by a standards body; no government, no pharmacopoeia and no standards organisation issues one. The phrase was coined inside this industry, by companies, to describe their own products.
That includes the standard behind the oils in this app. CPTG — Certified Pure Tested Grade — is doTERRA’s own mark, defined and administered by doTERRA, and it is not an external certification. A standard is worth something because of what is done under it and whether you can check the results.
There is no grade
Nothing on an essential oil label is a grade the way a grade of steel is — a specification written by somebody other than the seller, with a consequence for failing it. When you read a quality word on a bottle, the question is not what it means. It is who administers it.
Two real bodies of specification do exist, and they are worth knowing about even though neither is a grade. The international and national standards organisations publish composition standards for individual oils — one document for *Lavandula angustifolia* oil, another for *Mentha piperita* oil — each setting out the range every major constituent should fall inside, along with physical measures such as relative density, refractive index and optical rotation. Separately, the pharmacopoeias, which are the official compendia of drug quality, carry monographs for the handful of oils used in medicines, with their own identity and purity tests.
Those are genuine specifications. Somebody other than the seller wrote them, and a sample can be tested against them. What they are not is a ranking of quality. A composition standard says this material falls inside the range this species normally produces. It says nothing about whether the plant was well grown, whether the still was run for its full time, or whether the liquid was assembled rather than distilled.
And there is a sharper problem underneath. A published composition standard is, read from the other side, a list of exactly the numbers a laboratory is going to check. Anyone building a cheap oil up to pass is aiming at precisely those numbers, because those are the only ones that get looked at. Conformance is therefore evidence that somebody hit a target — which is not the same as evidence that the oil came out of a plant. That is why the interesting tests are the ones asking questions no composition standard asks: which mirror form, and which isotopes. And it is why no single number ever settles this.
Set the marketing words aside and a definition holds up. An essential oil is pure when it is the whole distillate of the named species, from the named plant part, nothing put in and nothing taken out since the still.
The named species
Lavender is *Lavandula angustifolia*. Lavandin is *Lavandula × intermedia* — a different plant with its own chemistry. Both are called lavender in speech; only one is lavender on a label.
The named plant part
Lemon is cold pressed from the peel; distil the leaves of the same tree and you get petitgrain, at a different price.
The whole distillate
Nothing removed matters as much as nothing added. Take a constituent out to lighten a colour and what is left is a fraction of an oil. The minor compounds are most of the compounds — dozens to hundreds, most under one per cent — and the oil effect is why they matter.
Since it left the still
Purity is a property of a history: what has been done, and by whom, between distillery and shelf.
Two failure modes follow. Dilution: a cheap odourless carrier is stirred in, volume goes up, every constituent proportionally weaker. Extension: a cheaper oil, or a factory-made compound, is added so the mixture still reads as the named oil — which is why it is harder to detect and more common to meet.
Purity and quality are not synonyms. An oil can be perfectly pure and still be poor — grown on tired soil, cut at the wrong moment, run through the still for less time than the method needs. Integrity is both: an unaltered oil from plant material worth distilling in the first place.
Adulteration is a craft with a literature, documented by the chemists who spend careers detecting it. A named method is something you can ask about, and harder to hide behind.
What follows describes practices, not businesses. Every one appears in published authentication work. None is attributed here to anyone, and none should be assumed of any bottle without evidence.
| Method | What is done | Most often seen with |
|---|---|---|
| Extension with a related oil | A cheaper oil from a nearby species is blended in, sharing most of the same constituents, so the profile still reads correctly. | Lavender with lavandin; rose and melissa with geranium |
| Addition of a synthetic constituent | A batch arrives low on its main compound, so that compound, made industrially, lifts it back into range. | Linalool in lavender; methyl salicylate, 98%+ of wintergreen and cheap to synthesise |
| Species substitution | A different species under a shared common name. Nothing mixed — the wrong plant was distilled. | Cornmint sold as peppermint; other woods sold as sandalwood |
| Rectification or re-distillation | An oil with an off note goes back through a still and the offending fraction is drawn off. Cleaner, and no longer the whole distillate. | Citrus oils and the mints, after a difficult season |
| Dilution with a carrier | An odourless fixed oil is stirred in to increase volume. It does not appear in a constituent profile. | The expensive materials: rose, melissa, helichrysum, sandalwood |
Diagram to come
Five small panels in a row, stacking to a column on a phone, each showing an identical amber bottle with a different thing going into it, drawn plainly enough to read at a glance. Panel 1: a second, paler bottle labelled as a related species pouring in. Panel 2: a laboratory flask holding a single compound, drawn as one molecule shape repeated over and over, being added by pipette — the repetition is the point. Panel 3: two similar-looking plants side by side with an arrow from the wrong one straight into the bottle, and no mixing anywhere in the panel. Panel 4: the bottle going back through a small still with one fraction being drawn off and set aside. Panel 5: a clear colourless carrier oil being poured in and the liquid level visibly rising. Beneath each panel, one line stating whether a constituent profile would still look right. Four of the five must read as "still looks right" and only the fifth as "looks thin" — that contrast is what the drawing exists to deliver.
Extension works because the plants really are similar: lavandin shares lavender’s main constituents, and what gives it away is the wrong compound appearing rather than the right one disappearing — several per cent camphor, where true lavender makes very little. The synthetic constituent is subtler, because the molecule added is not a fake. Laboratory-made linalool is linalool; what is missing is everything around it, since a plant building linalool builds a family of related compounds off the same pathway and a drum of purified linalool brings only itself. Species substitution needs no chemistry at all: cornmint yields far more oil than *Mentha piperita*, so strip the menthol out and what remains can be sold as peppermint to anybody not reading the botanical name.
Not every removal is deceit, and the distinction is worth carrying. Several kinds of processed oil are standard articles of commerce, sold openly under their own names, and a healer who calls all of them adulteration will be wrong in public.
Rectified
Re-distilled to take out a fraction — a colour, a heavy note, a compound restricted in cosmetics in some markets. Entirely legitimate when it is declared and the product is sold as rectified. It stops being legitimate at the moment it is sold as the whole oil.
Folded
A citrus oil concentrated by removing part of its monoterpene fraction. A fivefold lemon oil is a normal flavour-industry material with a longer life and more taste per drop. It is not lemon essential oil, and should not be priced or used as though it were.
Terpeneless
The same idea taken further — most of the hydrocarbon terpenes stripped out, leaving the oxygenated fraction behind. Used in flavour and fragrance work, where the terpenes cause solubility and stability problems.
The honest version of all three is a label that says what was done. The dishonest version is the identical liquid in a bottle that says pure. That is the general shape of this whole subject: almost nothing on the list of methods is illegal chemistry, and almost all of the harm sits in what the label does not say.
Dishonesty explains very little. The explanation is arithmetic: yields are tiny, the price spread runs into three orders of magnitude, the chain from grower to brand runs through six or seven businesses, and nobody downstream can tell. An oil that changes hands six times has six opportunities to be improved, and not one of the six need think of himself as a fraudster to take one.
Photograph to come
Pickers in a Damask rose field in the half hour after sunrise — wicker baskets or cloth sacks tied at the waist, bushes at chest height, mist still sitting on the ground. Shot wide enough to show how many bushes and how many people are involved, and close enough to see that every blossom is taken by hand, one at a time. No product, no bottle, no branding anywhere in frame. The photograph has one job: make a reader feel the ratio between that field and a five millilitre bottle.
Rose makes the case better than any general statement, because the numbers are large enough that you do not need a calculator to feel them.
The yields are tiny
Depending on species and part, a tonne of plant material might give several kilos of oil, or a few hundred grams, or less. For some oils the raw material behind one small bottle is hundreds of kilos of crop; for others it is a by-product that was going to be thrown away.
The price spread is enormous
Per litre, the gap between the cheapest and dearest oils in ordinary commerce runs into three orders of magnitude. Wherever two materials smell related and one costs a thousand times the other, the temptation is structural rather than personal.
The chain is long
An oil can pass through a grower, a distiller, a local collector, an exporter, a broker, a blender and a packer before it reaches whoever puts a brand on it. Pressure applies at every handover, and a small adjustment at each compounds into a large one by the end.
Nobody downstream can tell
The person who could detect a ten per cent extension by nose alone is rare, works in the trade, and was not in the room. Everybody after that point is taking the previous person on trust — and trust with no verification behind it is just optimism.
Rose oil is steam distilled from the flowers of *Rosa damascena*. The figure carried in the oils library is approximately sixty thousand blossoms for one ounce of oil. An ounce is about thirty millilitres, so a five millilitre bottle — the size rose is sold in, and the size is itself a piece of information — takes somewhere near ten thousand blossoms.
Those blossoms are picked by hand in the few hours after dawn, because the oil content of the flower falls away as the day warms. At roughly three grams a blossom, ten thousand of them is about thirty kilos of petals, gathered by people bending over bushes in the half dark, for one small bottle. None of that cost can be engineered away. It is the plant’s own arithmetic, and it has not changed in two thousand years of cultivation.
Now set it beside a lemon. Lemon oil is cold pressed from peel, and the peel is what is left after the fruit has been juiced — a material that already exists in industrial quantity and would otherwise be waste. Both bottles sit in the same drawer, look identical, and their raw material costs are not in the same universe.
Give that gap a shape. Suppose an expensive oil is worth several hundred times a cheap one that smells related to it. Replace one part in ten of the expensive oil with the cheap one, and you have taken nearly a tenth out of your cost while changing the aroma very little — little enough that most people, including most people in the trade, would not notice. Now let that happen at four separate points along the chain, each party taking their own modest tenth. Nine tenths, four times over, leaves about sixty-six per cent: the oil that arrives is a third something else, and every individual step along the way was a small one.
This is the honest reason adulteration is common. Not that the trade is full of criminals, but that the incentive at each step is small, easy and very nearly invisible — and there are a great many steps.
Which is why the answer is structural rather than moral: the same growers year after year, paid enough that nobody needs to stretch a batch, every lot tested on arrival. That is what sourcing is for.
Every method in that table leaves something behind. Analytical chemistry is choosing the question that makes the trace visible, and three instruments do most of it: what is in here and how much (GC/MS), whether a constituent is the mirror-image form a plant builds rather than the near-equal mixture a synthesis gives (chiral GC), and whether the carbon was fixed by a plant at all (isotope ratios).
What is in here, and how much of each
Gas chromatography joined to mass spectrometry — GC/MS. The chromatograph separates the oil into its individual volatile compounds by how long each takes to travel a long, thinly coated capillary; the mass spectrometer then breaks each arriving compound apart and identifies it from the pattern of fragments. What comes out is the constituent profile — the first test anybody runs, and the one every other claim rests on.
Is this compound the form a plant makes
Chiral gas chromatography. Many constituents exist in two mirror-image forms, identical in mass and identical on an ordinary column. A plant’s enzymes are themselves shaped objects, so they build one form strongly in preference to the other; a factory synthesis has no such preference and delivers the two in close to equal amounts. On a column whose coating is itself chiral the pair separate, and the ratio answers the question.
Did this carbon come out of a plant
Isotope ratio mass spectrometry. Carbon fixed by a living plant carries a different ratio of its light and heavy forms from carbon out of a petrochemical feedstock; hydrogen carries a parallel signal, set by the water the plant drew up. The instrument does not identify the compound at all — it weighs the atoms it is built from. This catches a nature-identical compound every other test would pass.
Then the tests for what gas chromatography cannot see. Anything that will not vaporise never enters the column, so a fixed vegetable oil stirred into a bottle is invisible to a constituent profile — the volatile fraction still adds to a hundred per cent and the profile looks untouched. Liquid chromatography catches it. Contamination is separate again: metals from soil, water or equipment, and microbial load.
Reading one of these reports is a skill rather than a mystery. Reading a constituent profile takes one apart line by line — the peak table, honest variation against adulteration, and where the paper stops.
A report certifies a batch, not a company
A test result describes one sample, drawn on one day, from one lot. It does not certify the organisation that commissioned it, and a clean report on one batch says nothing about the next off the still. Nor does it describe the bottle in your hand unless the lot number on the report is the one on the bottle. What makes a programme worth something is that every batch produces a report, that somebody independent runs it, and that a failed batch goes somewhere other than into bottles.
CPTG stands for Certified Pure Tested Grade: a panel of eight tests every batch must pass before it can be filled and sold, run by independent third-party laboratories as well as the company’s own. The standard as written is short — no synthetic fillers, no adulterants, no contaminants, and what the label names is what is in the bottle.
Video to come
A doTERRA laboratory walkthrough covering the batch testing panel end to end: a sample arriving with its lot number, the organoleptic bench, a GC/MS run being set up and read, and the non-volatile and contamination tests. The most valuable minute is the last one — what actually happens to a lot that does not pass, and who decides. That is the part no printed standard can demonstrate and the part a viewer most wants to see.
Two structural points. Independent third-party laboratories test each batch, so a result the company would rather not have comes from people whose business does not depend on the answer. And results are published per lot — every bottle carries a lot number, enterable at sourcetoyou.com to retrieve that batch’s results.
And now the part that has to be said plainly. CPTG is a company standard. doTERRA wrote it, doTERRA administers it, and there is no outside body that audits the mark or could withdraw it. Any company can write a standard and give it initials, and several have.
What separates one company standard from another is what sits underneath it, and three things are checkable on any of them, this one included: whether testing is done on every batch rather than periodically, whether the laboratories are independent of the seller, and whether you can retrieve the result for your own lot. The words on the front are not.
None of those instruments is in your kitchen, and you are still going to be offered bottles. None of this proves an oil is pure — nothing at home will. It sorts the bottles worth trusting from those worth questioning.
Diagram to come
Two sheets of plain white paper side by side, each with one drop placed in the centre, drawn at two moments: a small "after five minutes" panel and a large "after two hours" panel. Left sheet, a pure volatile oil — the drop is wet at five minutes and by two hours has almost gone, leaving a faint dry shadow. Right sheet, an oil cut with a fixed carrier — the drop at five minutes looks identical to the left one, and at two hours has spread into a translucent grease ring with a hard edge and paper visibly soaked through. A third, smaller panel underneath shows a heavy base-note oil leaving a residue of its own, flagged as a legitimate exception so the reader does not misread the test. Everything depends on the two-hour comparison being unmistakable at phone size, and on the five-minute panels being indistinguishable.
These are triage, not proof — but in a trade whose main protection is that nobody downstream checks, being the person who checks changes what you are offered. Two practical notes. If oil reaches your skin, wipe it off with a carrier oil rather than water, since oil does not rinse. And the expressed citrus oils — lemon, lime, grapefruit, bergamot and wild orange — are photosensitising: after any of them has touched skin, keep that skin out of direct sunlight and UV for up to twelve hours. Which oils are sold at all differs across the 65 markets this app serves, and so does what a label may say.
Keep oils away from eyes and inner ears, and out of reach of children. If you are pregnant, nursing, under medical care or taking medication, speak to your healthcare practitioner before use. Nothing here is intended to diagnose, treat, cure or prevent any disease.
Lesson 5 of 21 · Essential Oils