How to read a Certificate of Analysis.
Third-party lab report. Identity confirmed. Purity ≥98%. Endotoxin levels. Match the batch.
A Certificate of Analysis () is a third-party lab report that says: this vial contains the molecule the label claims, at the purity the label claims, with no contamination above safety thresholds. Without one you're guessing.
What to look for
A real shows: identity confirmation (mass spec match to the expected molecular weight), purity (typically ≥98%), endotoxin level (should be below 0.5 EU/mg for injectables), moisture content ( peptides should be under 8%), the batch number (must match the vial label exactly), the testing lab name + signature + date.
Red flags
No batch number. Batch number doesn't match the vial. Lab is the same company as the vendor (not third-party). "Purity" listed without method ( vs UV vs GC matters). not tested. Date older than 12 months. Anything over-rounded ("99.9999%" is suspicious).
Capped vials
A capped vial that has been stored too long or improperly can degrade even with a clean . Look for: discoloration of the powder, visible particles after , off odor. When in doubt, throw it out.
Vendors that publish COAs by default
are not necessarily safer than those that don't. They're just more transparent about being checked. Ask for a before you order. If they can't produce one, walk away.
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