What a certificate of analysis for cannabis resin tells you, and what it doesn't: the header, cannabinoids and total THC, pesticide residues, aflatoxins and microbiology, explained with an illustrative example.
For a licensed buyer, the certificate of analysis (COA) is the most important document in a resin purchase. It tells you what you are importing, whether it meets your market's limits and whether the batch you receive is the batch that was tested. Yet COAs vary widely in layout, depth and language, and the details that matter most are often in the footnotes.
This guide takes a cannabis resin COA section by section, the way an importer's quality team reads one: the header, cannabinoids, pesticide residues, mycotoxins, microbiology and the fine print.
Before looking at any number, read the header. It tells you which sample the results belong to, and a COA is only as useful as that link.
| Field | Example (illustrative) | What to check |
|---|---|---|
| Client | The producer's company name | Matches the legal entity on the producer's licences |
| Sample type | Cannabis resin | Matches the product you are buying |
| Identification | Lot: EXAMPLE-001 | The lot number matches your delivery |
| Sampling place | Production unit | Where the sample was taken |
| Sampling date | Day 1 | How old the data is relative to your shipment |
| Received / analysed | Day 2 | Time between sampling and analysis |
| Report issued | Day 4 | The report date, not the sampling date |
| Sampled by | The laboratory | Who took the sample: the lab or the producer |
Three questions matter most here. Is the lot number the lot you are buying? A COA for a different lot tells you about the producer's typical quality, not about your goods. How recent is it? Cannabinoid levels can change during storage, so an older COA is less representative. Who took the sample? Laboratory sampling or a documented sampling plan gives more assurance than a sample picked and sent by the seller. The report's fine print usually says who was responsible.
The cannabinoid section is the one most buyers read first. Resin is usually analysed by liquid chromatography (HPLC), often with UV detection (HPLC-UV). An illustrative result might look like this:
| Cannabinoid | Example result (illustrative) |
|---|---|
| CBDA | 1.00% |
| CBD | 3.00% |
| Total CBD | 3.88% |
| THCA | 20.00% |
| THC | 2.00% |
| Total THC | 19.54% |
Acid and neutral forms. Cannabis makes cannabinoids in their acid forms, THCA and CBDA. Heat converts them to THC and CBD (decarboxylation), and so does time, slowly. HPLC does not heat the sample, so it measures the acid and neutral forms separately. That is why a good resin COA lists both.
How "total" is calculated. When THCA loses its carboxyl group it also loses mass, so 1 g of THCA gives about 0.877 g of THC. The standard formula is:
In the example: 2.00 + 0.877 × 20.00 = 19.54%. Total CBD works the same way: 3.00 + 0.877 × 1.00 = 3.88%. Checking this arithmetic on a real COA takes ten seconds and confirms the lab used the standard conversion.
What to ask. Is the percentage weight per weight (w/w)? What is the measurement uncertainty? Many reports print neither, and conclusions are often stated without accounting for uncertainty. If your contract has a potency threshold, agree how uncertainty is handled. Also note which cannabinoids were tested: if your specification needs CBG, CBN or other minor cannabinoids, ask for them explicitly.
Pesticide screening is where resin COAs differ most, because the number of substances tested can range from a handful to several hundred. Broad screens typically run on two instruments:
In Europe, laboratories often base their method on NF EN 15662, the European standard for multi-residue pesticide analysis, and assess results against EU maximum residue limits (MRLs).
Three things to read carefully:
A detail worth knowing: long pesticide tables often list only the substance and its LQ, with the overall result in a single conclusion line. That is normal. It means nothing was quantified, so there is no per-substance value to print.
Resin comes from dried plant material, and poorly dried or badly stored material can grow moulds that produce mycotoxins. Laboratories commonly test the four regulated aflatoxins by UPLC-MS/MS or a similar method:
| Aflatoxin | Example result (illustrative) | Example LQ |
|---|---|---|
| B1 | < LQ | 0.5 µg/kg |
| B2 | < LQ | 0.5 µg/kg |
| G1 | < LQ | 0.5 µg/kg |
| G2 | < LQ | 0.5 µg/kg |
| Total aflatoxins | < LQ | 2.0 µg/kg |
Note the units: µg/kg, a thousand times smaller than the mg/kg used for pesticides. Look too for a footnote on recovery. Many labs report results "not corrected for recovery", meaning they report what they measured without adjusting for the share of analyte lost during sample preparation. That is common practice, but it matters when results are close to a limit.
Aflatoxins are not the only mycotoxins. Depending on your market, your specification may also require ochratoxin A. If it is not on the COA, ask for it before the contract rather than after the goods arrive.
For markets that apply pharmaceutical expectations, microbiology is often tested with European Pharmacopoeia methods: 2.6.12 for microbial counts and 2.6.31 for specified micro-organisms in herbal products. Results are assessed against stated criteria:
| Test | Method | Example criterion | Example result (illustrative) |
|---|---|---|---|
| Total aerobic microbial count | Ph. Eur. 2.6.12 | ≤ 10⁵ CFU/g | 1.0 × 10³ CFU/g |
| Total yeast and mould count | Ph. Eur. 2.6.12 | ≤ 10⁴ CFU/g | 1.0 × 10² CFU/g |
| Escherichia coli | Ph. Eur. 2.6.31 | Absence in 1 g | Absence |
| Salmonella | Ph. Eur. 2.6.31 | Absence in 25 g | Absence |
| Bile-tolerant gram-negative bacteria | Ph. Eur. 2.6.31 | < 10⁴ MPN/g | < 10 MPN/g |
Reading the numbers. CFU means colony-forming units. "1.0 × 10³" (written 1,0.10³ on some French-language reports) is 1,000 CFU per gram. MPN is the "most probable number", a statistical count used for some tests. Absence tests are pass/fail, and the quantity matters: Salmonella is usually tested in 25 g, E. coli in 1 g. The criteria themselves come from your market's requirements or the pharmacopoeia edition cited, so check that they match your specification.
A detail that signals a careful lab. Good reports state that the method's suitability, including neutralisation of any antimicrobial activity in the sample, was tested on the product. Plant materials can suppress microbial growth in the test itself, which would make counts look better than they are. Validation rules that out.
Laboratory reports carry standard statements that are easy to skip and important to understand. Look for these:
None of these is a warning sign; they are how accredited laboratories normally report. But they define what the COA does and doesn't prove.
A COA answers only the questions that were asked. Depending on your market, product and use, your specification may also require:
The practical rule: agree the test panel, the laboratory and the acceptance limits in the contract, before the batch is produced or reserved.
Every batch of our solventless resin, from Dry Resin to Static Resin and Powder Resin, has a certificate of analysis. Cannabinoids are profiled in our on-site HPLC laboratory, every batch has a terpene profile, and contaminants are tested by independent laboratories. Full reports, together with our ANRAC authorisations and our LSQA WHO-GACP declaration, are shared with approved buyers in the portal. For the licences and test methods behind them, see Quality & Compliance. To evaluate a specific product, use the Request a COA button, or apply as a licensed buyer.
Most of the THC in resin is present as THCA, the acid form. Total THC converts THCA to its THC equivalent (multiplying by 0.877) and adds the THC already present. With illustrative values of 2.0% THC and 20.0% THCA, total THC is 2.0 + 0.877 × 20.0 = 19.54%.
The result is below the limit of quantification: the lowest concentration the method can measure reliably. It does not prove the substance is completely absent, only that any amount present is below that limit.
No. A COA describes the sample that was tested, and accredited laboratories state that results relate only to that sample. Match the lot number on the COA to the lot you receive.
Approved buyers find full laboratory reports in the buyer portal. You can also request a COA for a specific product with the Request a COA button on this page or on any product page.