You ask a supplier for an analysis and they send you a PDF. Before reading any number, check the following seven things.
One — is this for the lot you mean to buy
This is the most important question and also the one most often skipped.
Find the lot number on the analysis and compare it with the lot number that will be printed on the bottle you receive. If the analysis has no lot number, or has one that does not match, it only proves that at some point the supplier once had a lot that met the standard.
Two — how far is the date of analysis from the date of production
Essential oils change over time. Limonene oxidises, esters hydrolyse, caryophyllene oxide steadily rises.
An analysis from three years ago does not describe the bottle you are about to buy.
Three — which laboratory
The laboratory’s name, and preferably an independent laboratory rather than the supplier’s own in-house one.
An in-house laboratory is not automatically bad, but it is information you have a right to know.
Four — what is the chromatography column
If the analysis gives retention times without stating the column type, those figures are meaningless: retention times can be compared only between samples run on the same type of column.
Non-polar and polar columns give different elution orders. Without knowing the column, you cannot compare with any other analysis.
Five — the total percentage of identified components
Add it up. A reasonable figure usually falls between eighty and ninety-eight per cent.
Below eighty: something takes up space without being identified. Above ninety-nine: suspicious in the opposite direction, because natural raw materials almost always have a part below the identification threshold.
Six — are the species’ marker components present
Each species has a few compounds that almost only it has. Their absence says more than the presence of the main compounds.
Look them up on this site’s compound pages to find out which compounds mark the species you are interested in.
Seven — how many trace components
Count the lines with a share below one per cent. A natural essential oil usually has dozens of such lines.
An analysis listing only six or seven large peaks is either a shortened version or an unusually poor sample. Both deserve a follow-up question.
What the analysis does not say
It does not say whether it smells good. It does not say whether the compounds are natural or synthetic. It does not say whether the product is safe.
It says only what is in the sample and in what proportions — which is a great deal compared with a line on a label, but not everything. The last lesson of this part lists in full what it cannot answer.