Journal — Vendor reviews
What makes a vendor COA worth reading
Not all certificates of analysis carry the same weight. A short guide to the lines that matter, and the ones to skip.
What the lab actually tells you
Reading a COA
On this page · What a COA is (and isn't)
Every reputable peptide vendor publishes a certificate of analysis. Reading one well is a 90-second skill that filters most of the bad supply out of your funnel.
What a COA is (and isn't)
A COA is the third-party lab's report on a specific batch of a specific compound. It is not a manufacturer self-attestation, it is not a marketing document, and it is not transferable between batches. The page reads dry on purpose — its job is to be checkable.
- Compound identity (mass spectrometry, HPLC).
- Purity percentage and the impurity profile.
- Net peptide content — not the same as bottle weight.
- Batch ID and the date the assay was run.
Three things to actually check
- Match the batch ID on the COA to the batch ID on your vial. If they don't match, the document is decorative.
- Confirm the lab is independent. A COA on the vendor's letterhead is a self-assessment, not a third-party assay.
- Read the impurity profile, not just the headline purity number. A 98% number with three named impurities is more useful than a 99% number with no breakout.
If a vendor won't publish the impurity breakdown, the purity number on its own isn't telling you what you think it is.
Common COA red flags
Stale dates. Same COA across multiple batches. No lab name. Net peptide content missing or quietly removed. PDF that resists copy-paste (a tell that the document was rasterized to hide a field). None of these are dispositive — taken together they are.