Good morning. Back in No. 01 we walked through what a certificate of analysis actually reports: batch numbers, purity, the method behind the number. That was how to read the document. Today is harder and more important. It is how to tell a real COA from a decorative one, because the polished ones are often the emptiest.
Who ran the test is half the answer
A COA with no lab named on it is a press release. The first question is not what the number says but who measured it. A genuine third-party COA carries the testing lab's name, its contact details, and a batch number you can ask the lab to confirm. A vendor that runs its own analysis and prints its own certificate is not disqualified, but it is grading its own homework. Those are different levels of evidence, and a confident layout does not close the gap between them.
The tell is verifiability. If you cannot trace the COA back to a lab that will confirm it ran the test, the document is a design choice, not a data point.
A certificate you cannot verify is not weaker evidence. It is decoration that happens to contain numbers.
What the COA does not test
Even a real, third-party COA has edges. Most peptide COAs report purity and identity. Far fewer report content, which is the actual quantity of peptide in the vial against what the label claims. Fewer still address sterility or endotoxin. A vial can be 99% pure and still contain less than it says, or be tested for the wrong thing entirely. Purity answers "is it clean." It does not answer "is there as much as you paid for." Those are separate questions, and most certificates only answer the first.
This is where it meets last week's math. A vial that wins on per-mg price means nothing if the COA is hollow, and a slightly higher per-mg cost backed by a verifiable third-party certificate is often the cheaper purchase once you account for what you are actually getting.
Worth your weekend
If you want to see how the professionals think about this, read a published analytical method paper for peptide identity confirmation. You do not need to follow the chemistry. Watch instead for how much qualification a real lab puts around a single result. That caution is the whole point, and it is exactly what a one-line "≥99%" leaves out.
Reply if a vendor has shown you a COA you could not make sense of. Those are the ones we learn the most from.