1. Start with the header: does it match what you ordered?
Before looking at a single result, confirm:
- Product name matches what you purchased.
- Lot number matches the lot number printed on your product's label or packaging — not just “a lot number,” but your lot number.
- The company the test was issued to. The COA should name the company that submitted the sample for testing. If that name does not match the seller you are buying from, be skeptical of how that COA relates to the product in front of you (more on this in section 5).
A note on test dates: lyophilized (freeze-dried) powder has a shelf life of years when stored properly, so a COA dated more than a year ago is not automatically a red flag — the material does not need to be retested on a schedule just because time has passed. What matters is that the lot number on the COA matches your product, not how recent the test date is.
If a seller sends you a COA with no lot number, or a lot number that does not match what is on your product, stop there. That COA could be for any batch, including one that failed and was never sold. A COA without a matching lot number proves nothing about what is in your hands.
2. Understand what the numbers actually mean
A real COA from a competent lab typically reports:
- Identity: confirms the compound is actually what it claims to be, not a different substance entirely.
- Purity: what percentage of the material is the target compound versus other substances.
- Quantity / potency: how much active material is actually present relative to what the label states.
- Additional panel items, such as contaminant and microbial screening, depending on the lab and product type.
Purity and potency are not the same thing, and sellers sometimes blur this. A product can test at high purity (the material present is chemically correct) but still be underdosed (there is simply less of it per vial than claimed). Look for both numbers, not just the headline purity percentage. For more on the purity number, see HPLC Purity Explained.
3. Verify the lab is real and independent
This is the step most buyers skip, and it is the one that actually catches fraud.
- Search the lab's name. A legitimate third-party testing lab has a public presence, a real address, and a method it is willing to describe.
- Be skeptical of results from a lab that only seems to exist on the seller's own paperwork, or that shares a name or address with the seller's company.
- Reputable labs often use standard analytical methods (HPLC, mass spectrometry). The COA should name the method used, not just list a number with no context.
- Some testing labs offer an online lot-verification tool where you can independently look up a result by lot number, outside of anything the seller sent you. If one is available for the product you bought, use it.
4. Watch for the actual red flags
- Numbers that are suspiciously round or identical across different lots or products (real lab variance is not that clean).
- No lab name, no lab contact information, or a lab name that cannot be found anywhere else.
- A PDF with inconsistent fonts, misaligned tables, or signs of being edited from a template.
- A COA that is clearly generic — the same document reused across unrelated products or lot numbers.
- A seller who cannot produce a lot-specific COA on request, or pushes back when asked for one.
5. Make sure it is actually for your product
Two things have to line up, not just one: the lot number on your product's label has to match the lot number on the COA, and the COA has to have been issued to the company you are actually buying from — not a different distributor, not a manufacturer three steps up the supply chain with no stated connection to your seller. A real, traceable COA names who the lab tested the sample for. If a seller hands you a certificate issued to some other company's name with no explanation of the relationship, that is a gap worth asking about before you assume it covers what you are holding.
For a field-by-field walkthrough of a typical report, see How to Read a Peptide Certificate of Analysis.