What a COA actually is
A Certificate of Analysis is a third-party laboratory's report on a specific batch of product. The key words are third-party and batch. A report produced in-house, or one that does not match the batch code printed on your bottle, tells you very little.
The four things to check first
- Batch or lot number matching the label on your product
- Test date within roughly the last year
- Cannabinoid potency close to the amount claimed on the label
- Passing results for pesticides, heavy metals, residual solvents, and microbials
Reading the potency table
Potency is usually reported in milligrams per gram or as a percentage, alongside a total per container. Convert to what is on your label: a 30 mL bottle claiming 1,000 mg should work out to roughly 33 mg per milliliter. A gap of a few percent is normal; a gap of thirty percent is not.
ND, LOQ, and other abbreviations
ND means not detected. LOQ is the limit of quantitation — the smallest amount the instrument can measure reliably. A result reported as "<LOQ" means a trace may exist below the measurable threshold, which is why full-spectrum products can still show a THC value near zero rather than exactly zero.
Red flags
No batch number, no lab name, a report older than the product, a potency table with no contaminant panel, or a company that will not send a COA on request. Any one of those is reason enough to buy something else.