The only document that proves what is in the vial
You are about to spend $200 or more on peptides. A Certificate of Analysis is the only document that tells you what you actually bought.
Everything else is marketing: the website design, the reviews, the Instagram presence, the confident product copy. The COA is data.
Three tests matter.
HPLC purity
What it tells you: what percentage of the sample is actually the peptide on the label, as opposed to fragments, impurities or degradation products.
Minimum standard: ≥98%
High-Performance Liquid Chromatography separates the components of a sample and measures how much of each is present. A 98% result means 98% of what is in that vial is the compound you paid for.
Below 95% is unacceptable for a research peptide. Independent testing of gray-market products has found purity as low as 60%, meaning nearly half of what you would be injecting is something else.
Mass spectrometry
What it tells you: identity confirmation. It proves the molecular weight matches the target compound.
Minimum standard: molecular weight within ±1 Da of expected
This is the test people skip and should not. HPLC tells you the sample is 98% one thing. Mass spectrometry tells you what that thing is.
Without identity confirmation, a vial labelled BPC-157 could contain a different peptide entirely, at 98% purity, and the HPLC result would look perfect. Purity without identity is a number about nothing.
Endotoxin / pyrogen testing
What it tells you: bacterial contamination.
Minimum standard: <0.5 EU/mg by LAL test
Endotoxins are fragments of bacterial cell walls. They survive sterilisation, they are not removed by filtering, and they cause fever, inflammation and, in severe cases, organ damage.
This is critical for anything injectable, and it is the test most commonly missing from a COA. A product can be pure, correctly identified, and still make you seriously ill if it was manufactured in contaminated conditions.
Reading an actual document
When a COA lands in front of you, work through it in this order:
- 1.Is there a batch number, and does it match your vial? A generic PDF that is not tied to a specific lot tells you about some other batch, not yours.
- 2.Who ran the test? A third-party laboratory name and address, not the vendor's own lab.
- 3.HPLC result: find the purity percentage. Is it ≥98%?
- 4.MS result: find the observed molecular weight. Is it within 1 dalton of expected?
- 5.Endotoxin result: is it present at all, and is it below 0.5 EU/mg?
- 6.Date: how old is this test?
If any of the three tests is absent, you are missing a category of information, not a detail.
What a COA cannot tell you
It cannot tell you the vial was stored correctly between the test and your doorstep. Cold-chain shipping matters for exactly this reason: peptides degrade without refrigeration in transit.
It cannot tell you the vendor did not test a good batch and ship a different one. That is what batch-specific COAs and consistency over time are for, and it is why the supplier scorecard in this module weights reputation over months rather than days.