Understanding Certificate of Analysis (COA): How to Verify Peptide Purity
Learn how to read a Certificate of Analysis, what purity percentages mean, and why COA is the single most important factor when choosing a peptide supplier.
Why COA Matters
In the peptide market, a Certificate of Analysis (COA) is the difference between knowing what you have and guessing. It is a document produced by an independent, third-party laboratory that verifies the identity and purity of a compound.
Without a COA, you have no way to confirm that what's in the vial is actually what the label says it is.
What a COA Contains
A legitimate COA typically includes:
- HPLC Purity Test — High Performance Liquid Chromatography measures the percentage purity of the peptide. Research-grade peptides should show ≥98% purity.
- Mass Spectrometry (MS) — Confirms the molecular weight matches the expected compound, verifying identity.
- Endotoxin Test (LAL) — Tests for bacterial endotoxins that could cause adverse reactions.
- Appearance — Physical description of the lyophilised powder.
- Batch Number — Unique identifier linking the product to a specific production run.
- Date of Analysis — When the testing was performed.
Red Flags in COAs
Watch out for:
- Missing HPLC data — The most critical test for purity
- No batch number — Suggests the COA may not correspond to your specific product
- Generic or template-looking documents — Legitimate labs produce detailed, specific reports
- Purity below 95% — Below research-grade standards
The Peptides & You Standard
Every product from Peptides & You is:
- Third-party lab tested by independent laboratories
- Supplied with a Certificate of Analysis for every batch
- Verified for identity (mass spectrometry) and purity (HPLC)
- Lyophilised powder format for maximum stability
We believe transparency is non-negotiable. You should never have to take a supplier's word for it — you should be able to verify it yourself.
All products are lab tested. COA included with every order.