How to Read a Cilantro Oil GC/MS Report
A GC/MS report looks like a verdict: a list of molecules with a percentage beside each one. It is better read as a fingerprint. The percentages are shares of what the instrument detected, not amounts of anything, and once that clicks, the rest of the page gets much easier to read.
Cilantro Essential Oil
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Each figure is the size of one peak divided by the total of all the peaks. So the column always adds up to roughly 100, whatever is in the bottle, and if one compound shrinks, every other percentage rises. A high decanal figure might mean there is a lot of decanal, or it might mean something else is missing. That is reasoning from how the method works, and it is the single most useful thing to carry into any report.
The method also only sees what travels through the instrument. Heavy vegetable carrier oils do not, as a rule, so a GC/MS table on its own cannot show whether an oil was cut with one. Whether an oil is sold neat is a statement you take from the seller, and ours is sold neat and undiluted.
Look for the leaf pattern
This is the part we care about, because it separates cilantro leaf oil from coriander seed oil. Machado et al., 2023 analysed eleven Portuguese coriander samples, and the fruit oils were dominated by linalool at 60 to 73%, while the aerial-part oils were led by 2-trans-decenal at 37 to 63% and n-decanal at 13 to 30%. In plain terms, seed oil is a linalool story and leaf oil is an aldehyde story.
Kumar et al., 2022 steam-distilled fresh leaves of four cultivars and found the same family with different proportions.
| Compound | Portugal, aerial parts (Machado 2023) | Four cultivars, steam-distilled leaf (Kumar 2022) |
|---|---|---|
| (E)-2-decenal | 37 to 63% | 15.7 to 25.1% |
| Decanal | 13 to 30% | 14.4 to 18.8% |
| Linalool | Leads the fruit oils, 60 to 73% | 0.1 to 0.5% |
The two papers agree on who is in the room and disagree on how much space each takes up. They differ in cultivar, climate, plant material and distillation method, so the gap does not mean either is wrong. The sensible way to read a leaf oil report is therefore to look for the pattern, with aldehydes and their alcohol relatives out in front and linalool a minor player, and not to hunt for one correct decanal number. A report on a so-called leaf oil that puts linalool at the top is describing a seed-type oil, whatever the label says.
If you only ever do one thing with a report, make it the lot number check. It takes ten seconds, it needs no chemistry, and it tells you whether the page in your hands has anything to do with the bottle on your table.
Read the footer before the peaks
- Lot number and date. A report with no lot number describes a type of oil, not your bottle.
- Who ran it and how. The column and method let someone else compare the figures. A laboratory name gives you someone to ask.
- Retention indices. A compound name with a retention index beside it has been checked against a reference position. A name on its own is closer to a library guess. That is general practice in the field, not something specific to coriander.
- Unidentified share. A table that names 99% of the area looks tidy, but ask how much is genuinely unknown.
What a good report still cannot say
It cannot say where the plants grew or in what year, and it cannot say that the bottle in your hand came from the lot that was tested. It also cannot easily tell a plant-made aldehyde from a manufactured one, since a molecule is the same molecule either way. That one is our reasoning from chemistry, and it is why a report works best next to a lot number and a seller you can ask.
Be patient with the page
The first report you open can feel like another language. You do not need to understand every row. Pick three things: the two biggest peaks and the linalool line. Mark them, set the rest aside, and come back later. A report is a document to return to, not something to conquer in one sitting.
It also helps to have the bottle beside you. When the names on the page are abstract, a sniff of the oil with that waxy, citrusy edge makes the aldehyde words feel real.
A five-minute routine
- Match the lot number to your bottle.
- Check that the top peaks are decenal and decanal types, not linalool.
- Look for retention indices beside the names.
- Note who ran the analysis and by what method.
- Remember what stays invisible: carrier oil, origin and the source of the aldehydes.
The Certificate of Analysis on our site covers one batch and gives density, refractive index and optical rotation, which are physical measurements rather than a composition table. If you want a GC/MS report for your lot, ask us in writing through the contact page. For the wider buying picture see our buying checks, for what these molecules smell like see the aldehyde post, and for why a label word such as "therapeutic" is not evidence see this explainer.
Read the footer first, the pattern second, and the percentages last.
Cilantro Essential Oil
Cilantro Essential Oil from our own shop, in sizes from 0.5 oz to bulk.
From $13.99
Shop Now →Sources & Further Reading
- Machado A.M. et al., 2023, Chemical Variability of the Essential Oils from Two Portuguese Apiaceae, Plants 12(14):2749. PMC10384636
- Kumar S. et al., 2022, Chemical Composition of Fresh Leaves Headspace Aroma and Essential Oils of Four Coriander Cultivars, Front Plant Sci 13:820644. PMC8891447
