A Certificate of Analysis is a lab report. An independent laboratory is sent a sample from a specific production batch, runs it through a set of standard tests, and publishes what it found. It is the difference between a brand saying what is in a bottle and someone with no stake in the answer measuring it.

Here is what to look at when you open one.

Cannabinoid potency

This is the headline section. It lists each cannabinoid the lab detected — CBD, CBG, CBN, THC and others — with a measured amount, usually in milligrams per unit or as a percentage. The job of this section is simple: confirm that the milligrams printed on the label are really in the bottle. If the label says 1000mg of CBD, the potency panel should back that up. A small variance is normal; a large one is a reason to ask questions.

THC content

Hemp-derived products sold under the 2018 Farm Bill must contain no more than 0.3% delta-9 THC by dry weight. A COA shows the measured THC so you can see for yourself that the product sits under that federal limit.

• Full-spectrum products keep the plant’s whole cannabinoid profile, so a trace amount of THC will appear on the report — at or below 0.3%.
• Broad-spectrum products have had the THC removed, so it should read as non-detected or below the lab’s reporting threshold.

Neither is better than the other. They are different tools, and which one suits you is a conversation worth having in store. Our guide to full-spectrum vs broad-spectrum covers the difference in more detail.

Contaminant screening

Potency is only half the point. Hemp is a bioaccumulator, meaning it draws up whatever is in the soil it grew in, so a full COA also screens for what should not be there:

• Pesticides — residues from how the crop was grown.
• Heavy metals — typically lead, arsenic, cadmium and mercury, absorbed from soil and water.
• Residual solvents — traces of the solvents used to extract oil from the plant material.
• Microbials — bacteria, yeast, mold and mycotoxins.

Each of these appears as a pass or fail against a defined limit. A product that has been screened on all four is a product someone has actually checked.

Batch numbers — the part most people skip

A COA is not a certificate for a product. It is a certificate for a single production batch of that product. The batch that was made in spring and the batch made in autumn were grown, extracted and bottled separately, so each one gets its own sample, its own test and its own document.

That is why the batch or lot number matters. It is usually printed on the bottle, the box or the base of the jar, and it is the one piece of information that ties the thing in your hand to the report on the page.