How to Read a Peptide COA Before You Buy

A certificate of analysis (COA) is a lab report that documents what's actually in a vial. It is the single most important document in this entire space — and the fastest way to tell a real vendor from a repackager.

1. Who ran the test?

Look for a third-party lab, not the vendor's own claim. A COA from an independent lab (named, with contact info) is worth far more than a number printed on a label.

2. Does it match the batch?

A real COA is batch-specific — it references the exact lot number on the vial you're getting. A generic COA that could apply to anything is a red flag.

3. Purity — the HPLC number

High-Performance Liquid Chromatography (HPLC) measures purity as a percentage. The research-grade benchmark most serious vendors hit is 98–99%+. Anything materially lower, or missing, should give you pause.

4. Identity — mass spectrometry

Mass spec confirms the compound is actually what it claims to be, by molecular weight. Purity without identity is meaningless — you want both.

5. Endotoxins & sterility

For many research applications, an endotoxin test matters. Top vendors publish it. Its presence signals a vendor that takes documentation seriously.