How to Read a Peptide Certificate of Analysis (COA): A 2026 Research Buyer’s Guide

Short version: A Certificate of Analysis (COA) is the lab document that verifies what a research peptide actually is and how pure it is. When sourcing research peptides, the COA — not the marketing copy — is the real proof of quality. Here is how to read one, in plain English.

What a COA actually shows

A proper peptide COA reports three things: identity (is this molecule what the label says?), purity (what percentage of the sample is the target peptide?), and the test methods and batch number used to determine both. If any of those are missing, the document is not doing its job.

HPLC vs. Mass Spectrometry

• HPLC (High-Performance Liquid Chromatography) measures purity — it separates the sample and shows what fraction is the target peptide versus impurities. “99% by HPLC” is a purity figure.
• Mass Spectrometry (MS) confirms identity — it measures molecular mass to verify the peptide is the correct compound.

A strong COA includes both: MS to prove it is the right peptide, and HPLC to prove it is pure.

Why ISO/IEC 17025 accreditation matters

Anyone can print a document that says “99% pure.” ISO/IEC 17025 is the international standard for testing-laboratory competence. A COA from an ISO/IEC 17025-accredited lab means an independent body has verified the lab’s methods and results are reliable — a far stronger signal than an unnamed “third-party test.”

COA red flags

• No batch/lot number, or a COA that does not match the batch you received.
• The testing lab is not named — “third-party tested” with no lab to verify.
• No accreditation (ISO/IEC 17025) referenced.
• Only an identity test or only a purity test, never both.
• A single generic COA reused across every product instead of per-batch documents.

How Next Gen Peptides handles it

Every batch we supply is independently tested by ILS Labs, an ISO/IEC 17025-accredited laboratory, for both identity and purity, and the batch-specific COA is published in our COA Library. Review the documentation before you buy — browse the catalog here.

All products are supplied strictly for laboratory and in-vitro research use only (RUO). They are not intended for human or veterinary use, and no dosing or administration guidance is provided.