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Sourcing Peptides Safely: Reading a Certificate of Analysis
HPLC purity, mass spectrometry identity confirmation, endotoxin testing, and the red flags that indicate a recycled or fabricated COA.
The three tests that matter
HPLC establishes purity — look for ≥98% with a visible chromatogram, not just a printed number.
Red flags
No lab name, no analyst signature, or no test date on the certificate.
The same batch number appearing across multiple products, or a PDF with edited text layers.
Purity claims of 99.9% with no chromatogram attached.
A vendor offering dosing advice or medical claims — a legitimate RUO supplier will not.
Storage after you receive it
Lyophilized powder is stable for years at -20°C and months refrigerated. Reconstituted peptide is generally good for 3–4 weeks at 2–8°C.
Protect from light, avoid freeze-thaw cycles once reconstituted, and discard anything cloudy or with visible particulate.