If you've ever bought a CBD product — for yourself, your dog, or your horse — and wondered whether it actually contains what the label says, you're not being paranoid. You're being a sensible shopper. The CBD market in the UK is largely unregulated, and a 2023 analysis by the Centre for Medicinal Cannabis found that over half of UK CBD products tested were within 10% of their claimed cannabinoid content. Some were wildly off. The only reliable way to know what's in your bottle is the lab report — properly called a Certificate of Analysis (COA).

This guide explains what a COA is, what it must show, the red flags that should send you running, and how Gold Tree Organics publishes every batch report on our lab reports page.

What is a Certificate of Analysis?

A Certificate of Analysis is a third-party document produced by an independent laboratory that confirms exactly what's inside a specific batch of a CBD product. It should not be produced by the brand itself, and it should not be a one-off from the day the product launched. Every production batch should have its own COA dated within the last 12 months.

A COA typically includes:

• The product name and batch/lot number
• The date the sample was received and tested
• The lab's name, accreditation (ISO 17025 is the gold standard), and signature
• The actual measured results — cannabinoids, terpenes, contaminants
• The methods used (HPLC is standard for cannabinoids)

If a brand can't tell you the batch number on the bottle, or can't produce a COA for that specific batch, treat it as a yellow flag at best.

The 6 things every CBD COA must show

Not all COAs are equal. A proper one covers six categories of testing. Skim the list — any missing category is a reason to ask questions.

1. Cannabinoid profile

This is the headline number. The COA should list the mg per container (or per gram) of:

• CBD — the active ingredient you actually bought it for
• THC — must be below the UK legal limit of 1mg per container, and ideally 0.0% for zero-THC products
• CBG, CBN, CBC, THCV — minor cannabinoids, especially relevant in full-spectrum products
• Total cannabinoids — the sum, which is what most labels use to claim "X mg CBD oil"

2. Terpene profile

Terpenes are the aromatic compounds in hemp (and many other plants). They shape the effect of a full-spectrum product through what's called the "entourage effect". A good COA shows individual terpene concentrations — typically myrcene, limonene, pinene, linalool, and beta-caryophyllene.

3. Heavy metals

Hemp is a bioaccumulator — it absorbs metals from the soil. UK and EU regulations require testing for lead, cadmium, mercury, and arsenic. All four should be reported as "not detected" or below the permitted limit (usually expressed in ppm).

4. Pesticides

Conventional hemp farming uses pesticides. Organic certification eliminates most of them, but a COA should still confirm none of the common ones (myclobutanil, imidacloprid, etc.) are detectable.

5. Microbials

Tests for yeast, mould, E. coli, Salmonella, and total aerobic count. This matters especially for edibles and pet products where the product may be in contact with food bowls or open skin.

6. Residual solvents

If a CBD extract was made using solvents (ethanol, butane, CO2 — the solvent isn't always removed 100%), the COA should show residual levels are below safety thresholds.

How to read a cannabinoid profile

When you open a COA, the cannabinoid section looks like a small table. Here's how to read it:

Cannabinoid	What it means	UK-relevant limit
CBD	The active compound you've paid for	No legal cap, but must match label within 10%
THC	The psychoactive compound in cannabis	Less than 1mg per container (UK law)
THCV / THCa	Trace THC-type compounds	Contributes to the 1mg total THC limit
CBG	Non-intoxicating, often called the "mother cannabinoid"	No limit; shows up in full-spectrum
CBN	Mildly sedating, forms as THC ages	No limit; typical in aged extracts

The most important comparison: the actual CBD content vs the claimed CBD content on the label. If the label says 1000mg and the COA says 850mg, that's a 15% shortfall — a meaningful difference for a £70 product.

Red flags in a COA

Some COAs are real but useless. Others are fabricated. Watch out for:

• "Pending" or "results to follow" — the lab test hasn't actually been done yet. Walk away.
• No batch number — a generic COA that doesn't match the bottle in your hand is worthless.
• Only cannabinoids tested — no heavy metals, no pesticides, no microbials. That's a marketing document, not a safety document.
• Lab name missing or untraceable — any UK or EU lab will have a website, address, and accreditation. If you can't find them, the COA may be made up.
• Round numbers on every line — real chromatography data is rarely perfectly round. Numbers like exactly 10.00% on every cannabinoid suggest the data was typed in by hand.
• THC reported as "ND" with no detection limit — "not detected" only matters if you know the detection limit. A lab with a 0.5% detection limit could "not detect" 0.4% THC, which is a problem.

How Gold Tree Organics publishes its COAs

Every product we sell has a COA for its current production batch. You can find them on our lab reports page, organised by product and dated. If you want to see exactly what's in a specific bottle, the batch number is printed on the label, and the matching COA is one click away.

For example, our full-spectrum CBD oil and our THC-free broad-spectrum oil both have published reports showing the full cannabinoid breakdown, terpene profile, and contaminant panels. So does our pure CBD isolate powder, which tests above 99% CBD.

When "lab-tested" isn't enough

"Lab-tested" on a label is one of the most abused phrases in the UK CBD market. It tells you nothing on its own. The questions to ask are:

• Which lab? (Look for ISO 17025 accreditation)
• For which batch? (Not "we test every year" — every batch)
• For what? (Cannabinoids only, or full contaminant panel?)
• Can I see the report? (If the answer is "we'll email it", ask why it's not already public)

A brand that publishes COAs openly is putting its money where its mouth is. A brand that hides them isn't.

FAQ: CBD lab reports

How do I know a COA is from a real lab?

Search the lab's name. Reputable UK and EU cannabis testing labs (Phytocontrol, ProVerde, Eurofins, TÜV) have websites, registration numbers, and ISO 17025 accreditation. The accreditation should be visible on the COA itself.

What if my product's COA is more than 12 months old?

Ask for a current one. Cannabinoid content can degrade over time, especially in poorly stored oil. A two-year-old COA tells you what was in the bottle when it was made — not what's in it now.

Are UK CBD brands required to publish COAs?

Not yet. Trading Standards can request them, and the FSA's novel food authorisation process increasingly requires batch-level data, but there's no law forcing brands to publish them on a website. That's why the ones who do deserve your trust more than the ones who don't.

The bottom line

A COA is the only proof you have that a CBD product contains what the label claims, and nothing it shouldn't. Learn to read the cannabinoid section, check the contaminant panels exist, and look up the lab. If a brand can't pass those three checks, spend your money elsewhere.

Want to see what a proper COA looks like? Browse our published lab reports or get in touch with our team if you'd like help reading one of your own.