Every listing on a research-peptide supplier’s site says “high purity.” Almost none of them show you the document that actually proves it. A Certificate of Analysis (COA) is that document — and knowing how to read one is the single most useful skill for evaluating a research supplier, full stop.
What a COA actually is
A Certificate of Analysis is a lab report, generated by a third-party testing facility, that verifies what’s actually in a specific batch (“lot”) of material — not the product line in general, that exact production run. A legitimate COA is lot-specific: the lot number on the vial should match the lot number on the document.
What it should include
A complete COA covers, at minimum: identity confirmation (is this compound actually what the label says it is), purity percentage (typically via HPLC — high-performance liquid chromatography), and sterility/endotoxin testing where relevant. Some also include mass spectrometry data confirming molecular weight.
Why lot-specificity matters
Purity can vary batch to batch even from the same manufacturer — raw material variability, synthesis conditions, and storage all play a role. A COA for “the product line” rather than the specific lot in front of you tells you almost nothing about what you’re actually holding. This is the detail most worth checking before anything else.
A reasonable standard to hold suppliers to
Ask for the lot-specific COA before you buy, not after. A supplier who can produce it immediately, tied to the lot number on the product, is operating the way a research supplier should. One that offers a generic or outdated document, or can’t produce one at all, is a reason to look elsewhere — regardless of how the listing reads.
This is the standard we hold ourselves to: every batch we ship carries its own lot-specific COA, third-party tested, available on request.
Research Use Only — Not for human consumption. For laboratory and analytical research use exclusively.