A certificate of analysis (COA) is worth reading only when it matches the exact package in front of you. Before you pay, find the batch or lot number on the label and confirm the COA shows that same number, a recent test date, and the license number of the lab that ran the panel. If the report cannot be tied to your batch, the potency figure on the jar is a claim, not a verified result.
why cannabis should be lab tested for pesticides
What Every COA Should Show
- Lab identity: legal name, license number, and accreditation. ISO/IEC 17025 is the international benchmark for testing and calibration labs.
- Sample details: batch or lot ID, product type, and the date the sample was collected.
- Report date: the date results were issued, which can differ from the collection date.
- Submitting party: who sent the sample, whether cultivator, processor, or retailer.
- Cannabinoid profile: THC, THCA, CBD, CBDA, and minor cannabinoids listed as separate numbers with totals.
- Contaminant panel: pesticides, heavy metals, microbials, mycotoxins, and residual solvents, each with measured values and the limit used to judge them.
- Method notes: the analytical technique used for each panel, such as HPLC for potency or ICP-MS for heavy metals.
Potency Math You Should Run Yourself
Raw flower holds most of its THC in acid form. Total THC equals (THCA x 0.877) + THC, where 0.877 accounts for the mass lost when THCA decarboxylates into THC. A jar labeled 30% THC that lists 32% THCA and 1% THC does not add up, because the converted total lands near 29%. Run the arithmetic on any number that looks out of line.
Contaminant Panels
A pass stamp tells you little on its own. Look for the measured result next to the action limit. A mold count of 9,000 CFU/g passes where the limit is 10,000 CFU/g and fails where the limit is 5,000. The same logic applies to pesticide residues and residual solvents, where legal thresholds differ by jurisdiction.
Parameter Bands Worth Knowing
- Flower potency: most regulated-market flower falls between 15% and 30% total THC. Numbers in the mid-30s and above deserve a closer look at the lab and batch.
- Water activity: 0.55 to 0.65 is a common target. Higher readings raise the risk of microbial growth.
- Moisture content: roughly 8% to 12% for dried flower.
- Total yeast and mold: limits range from 10,000 CFU/g to 100,000 CFU/g depending on the state.
- Heavy metals: lead, arsenic, cadmium, and mercury are the usual four, each reported in parts per million against a state limit.
Pitfalls That Fool Buyers
- A COA for a different batch than the one on the shelf.
- Reports with no lab license number, no batch ID, or no test date.
- Pass or fail stamps with no numeric results behind them.
- Stale paperwork for flower, where a report older than a few months says little about what sits in the jar now.
- QR codes that open a brand homepage instead of a batch-specific report.
- Lab shopping, where a producer tests one harvest at several labs and publishes only the highest potency result.
FAQ
Do I need to see the COA before I buy?
Ask for the batch number first. If the shop or seller cannot point you to a report for that batch, you are buying on trust.
Cannabis Lab Tested vs Untested Flower
Can a COA be faked?
Yes. Look for a lab license number you can check against state licensee records, and confirm the report date and batch ID line up with the package.
What does a pass mean on a contaminant panel?
It means every measured value fell under the limit that the testing state or jurisdiction applies. Without the limit printed on the report, the word carries no weight.
Are terpenes required on a COA?
Not everywhere. Some states require a terpene panel, others do not. When terpenes appear, check that the reported percentages are plausible and that the total does not exceed 100% alongside the cannabinoid numbers.
How old can a COA be?
Rules vary. For flower, a report from the current harvest or within a few months of packaging is more useful than one from a previous season.