Read a COA.
The jar tells you what the brand wants you to think. The certificate tells you what a laboratory measured, once, in one batch, on one date. Most buyers never open it, and most of the tricks in this trade live in the gap between the two. Below is a specimen certificate laid out like the real thing. Open any line and it explains itself: what the line means, what to check, and how it gets abused.
One page, every line a question.
Two specimens: the finished tincture a buyer sees, and the raw isolate a formulator receives. Select a line to open its note. The total-THC line shows its working: Δ9-THC plus 0.877 times THCA, the factor the site states on the THCA page, with both readings printed beneath it. No limits are printed anywhere, because limits vary by jurisdiction and the site holds none. The total-THC working, row by row has a page of its own.
Certificate of Analysis
1 · Sample and batch identification
- Specimen Analytical (fictional) · address and contact line
- What it means
- The organisation that ran the tests. Not the brand, and not owned by the brand.
- What to check
- A street address, a way to reach the lab directly, and a lab that is independent of the seller.
- The common trick
- A certificate the brand issued to itself, or one that names no laboratory at all.
- Example Botanicals (fictional)
- What it means
- Who commissioned the test and sent the sample. The lab reports what it was sent; it does not go and fetch a jar from a shelf.
- What to check
- The client is the brand on the jar or the manufacturer behind it.
- The common trick
- A certificate for another company's material, passed along as if it described this product.
- Example CBG tincture, 30 mL, oral (specimen)
- What it means
- The product as the client described it to the lab.
- What to check
- The name, form and size match the jar in your hand.
- The common trick
- A certificate for the raw extract shown as if it were the finished product. The numbers then describe a drum, not a bottle.
- SPEC-0001
- What it means
- The production run these numbers describe. A certificate is a statement about one batch.
- What to check
- The same batch string printed on the jar, and a fresh certificate for each batch.
- The common trick
- A COA without a batch number is decoration. One batch number on every certificate the brand has ever shown is worse.
- SA-26-0923-01 (specimen)
- What it means
- The lab's own identifier. It ties the certificate to the lab's records, which is what makes the certificate checkable.
- What to check
- That the lab can confirm the sample ID and the result if you ask. A real lab can.
- The common trick
- A QR code that leads to the brand's website rather than the laboratory's records.
- Oil, oral tincture
- What it means
- The physical form of what was tested. Methods and sample preparation depend on it.
- What to check
- The matrix matches the product you are buying, not an earlier stage of it.
- The common trick
- Extract tested, tincture sold.
- 2026-09-16 / 2026-09-19 / 2026-09-23 (specimen)
- What it means
- The test date is the date the numbers describe. Cannabinoid acids convert with heat and time, and neutral cannabinoids oxidise, so a panel drifts as the product ages.
- What to check
- A certificate current for this batch, with a test date you would accept as recent.
- The common trick
- One old certificate reused for every batch made since.
- Cannabinoids by liquid chromatography (specimen); contaminant methods listed per panel
- What it means
- The technique that produced the numbers, and the lab's procedure reference for it.
- What to check
- A named method for each panel. The lab should be able to say what it did.
- The common trick
- The phrase "third-party tested" with no method, no panel and no numbers behind it.
- mg/g (mass of analyte per gram of product) · density not stated
- What it means
- Milligrams of each cannabinoid per gram of tincture. A mass-per-mass figure, which is what the instrument reports.
- What to check
- For a liquid, the density, so mg/g can be turned into mg/mL, which is what a dropper measures. If the label is in mg/mL and the certificate is in mg/g, the density is the missing link.
- The common trick
- mg/g reported on a liquid with no density stated anywhere, so the label's mg/mL can never be reconciled to the certificate.
2 · Cannabinoid panel
| Analyte | Result (mg/g) | |
|---|---|---|
| ||
| 1.8 | 0.10 | |
| ||
| 25.0 | 0.10 | |
| ||
| ND | 0.10 | |
| ||
| 2.4 | 0.10 | |
| ||
| 0.6 | 0.10 | |
| ||
| 0.4 | 0.10 | |
| ||
| <LOQ | 0.10 | |
| ||
| 0.9 | 0.10 | |
| ||
| 0.93 | 0.4 + (0.877 × 0.6) = 0.4 + 0.53 = 0.93 mg/g | |
| Δ9-only 0.4 mg/g · total-THC 0.93 mg/g · which applies depends on jurisdiction | ||
| ||
ND: not detected at the method’s limit. <LOQ: detected, below the limit of quantitation. Total THC = Δ9-THC + 0.877 × THCA; the working is printed on the line, and both readings are printed beneath it because which one applies depends on jurisdiction.
3 · Contaminants
- pass · see method
- What it means
- A panel for metals the plant can take up from soil and water. Reported against a specification the certificate should name.
- What to check
- Which metals were tested, and against which specification. "Pass" has to say pass against what.
- The common trick
- "Pass" with no specification named, or a panel that quietly lists fewer metals than the specification asks for.
- ND · see method
- What it means
- A screen for a list of pesticide residues. The list is the substance of the result; ND against a short list is a short answer.
- What to check
- How many compounds the screen covers, and the LOQ for each.
- The common trick
- "Pesticide-free" from a screen of a handful of compounds.
- pass · see method
- What it means
- What remains of the solvents used in extraction. Relevant for any extracted product, and the panel depends on which process was used.
- What to check
- That the solvents tested match the extraction process the brand describes.
- The common trick
- A solvent panel from a different process than the one that made the product.
- pass · see method
- What it means
- Counts and presence tests for microbial contamination. The right panel depends on the route of use.
- What to check
- That the panel suits how the product is taken, and that the specification is named.
- The common trick
- A microbial line that exists on the certificate template and was never run.
No limits are printed on this specimen because the site holds none. A real certificate names the specification it tested against; limits vary by jurisdiction and product class.
4 · Accreditation and signature
- Not asserted for this specimen. A real certificate names its accrediting body, the standard it was assessed against (commonly ISO/IEC 17025) and a certificate number.
- What it means
- Accreditation means an outside body has assessed the lab's competence for a defined scope of tests. The specimen claims none.
- What to check
- The accrediting body, the certificate number, and that the scope covers the tests on this page.
- The common trick
- A logo with no certificate number, or a scope that does not include cannabinoids.
- Name withheld (specimen) · Laboratory Director · 2026-09-23
- What it means
- The person who stands behind the result, by name and title.
- What to check
- A named reviewer, a title, and a date that agrees with the issue date.
- The common trick
- An unsigned certificate. A PDF nobody has put their name to is a PDF.
Every number on this specimen is invented to teach the layout of a certificate. It describes no real product, laboratory, batch or result, and no value on it should be compared with a real one.
Twelve flags on an incoming COA.
The hotspots above, condensed to one screen. Each flag names the line it comes from. Open the printable version to keep it beside the instrument.
- 1No laboratory named, or the brand is the laboratory
A certificate needs an independent lab with an address you can reach. The brand testing itself is a claim, not a result.
- 2No batch or lot number
A COA is a statement about one batch. Without the number it describes nothing you can hold.
- 3The matrix is not the product
Extract tested, tincture sold. The numbers describe a drum, not a bottle.
- 4One old test date for every batch since
Acids convert and neutrals oxidise, so a panel drifts. Ask for a date you would accept as recent, per batch.
- 5Units that cannot be reconciled to the label
mg/g on a liquid with no density, or a label in mg/mL against a certificate in mg/g. Ask for the density or a matching unit.
- 6ND or <LOQ with no limit printed
Not detected against an unstated limit says very little. The LOQ column is the substance of every ND.
- 7Acid and neutral folded into one headline number
Total CBG that adds CBGA without saying so. Ask which figure the label counts.
- 8Only Δ9-THC on the THC line
Total THC is Δ9-THC plus 0.877 × THCA. A certificate that lists only Δ9 never writes the total down.
- 9Assay in area-percent presented as % w/w
A ratio of chromatogram peaks is not a mass. Ask for the assay against a reference standard, by weight.
- 10No impurity table on an isolate
A 98.6% assay with nothing named for the rest leaves the remainder unexplained.
- 11A solvents panel from the wrong process
Solvents the supplier never used, all clean; the one they did use, absent. Ask which solvents the process ran on.
- 12Pass with no specification, and no signature
Pass has to say pass against what, and someone has to put their name to it. An unsigned PDF is a PDF.
Same batch, two dates (illustrative)
Illustrative| Analyte | tested 2026-03-04 (specimen) | tested 2026-09-19 (specimen) | Direction |
|---|---|---|---|
| THCA | 0.9 | 0.6 | down |
| Δ9-THC | 0.2 | 0.4 | up |
| CBN | <LOQ | 0.2 | appears |
Illustrative values on a specimen batch. The directions are the chemistry: heat and time convert THCA toward Δ9-THC, and Δ9-THC oxidises toward CBN. The sizes are invented, and nothing here states a rate or a shelf life. A certificate describes the product on its test date and on that date alone. The chemistry behind each direction is modelled on Heat, time and light.
Three things to demand from any COA.
The same three checks the consumer guide asks for. They do most of the work.
Published per batch
A certificate of analysis for each batch, one you can actually open and read, with the full cannabinoid breakdown and a contaminant panel. If the seller cannot produce it, move on.
Milligrams per serving
CBG stated up front in milligrams per serving, and reconcilable to the panel. The words "proprietary blend" are where the number you needed goes to hide.
No disease claims
A reliable seller describes what is in the jar and leaves disease out of it. Any talk of effects stays conditional.
Three more, for the raw material.
The isolate specimen adds three documents to demand. The third is the stability report behind the retest date; what it has to contain is set out on the formulator page.
Assay by weight, with the remainder named
Percent by weight against a reference standard, an impurity table with a limit per named compound, and a water figure, so the mass balance can be read.
A solvents panel that matches the process
Ask which solvents the extraction and crystallisation used, then read the panel for those. A clean panel of the wrong solvents is a clean panel of nothing.
A retest date with a stability report behind it
A retest or expiry date, and the report that justifies it: storage conditions, timepoints, method and what was monitored. A date without a report is a guess with a calendar.
Informational only, not medical or legal advice; regulations vary by jurisdiction. Every number on this specimen is invented to teach the layout of a certificate. It describes no real product, laboratory, batch or result, and no value on it should be compared with a real one. To test the words on a label against the evidence ladder, use the Label Lab; to see how the site grades a claim, read how we grade. Report a safety event.