What a COA Does and Does Not Tell You

📅 August 14, 2026 ⏱️ 2 min read ✍️ Team TPS

“99% purity” on a certificate tells you less than most people assume, and understanding why is worth more than the number itself.

What a COA actually measures

A certificate of analysis for a peptide typically reports HPLC purity, how much of the material is the intended peptide versus other peptide-like material.

That is genuinely useful. It is also narrow: it does not measure whether the sequence is correct, whether the peptide is correctly folded, whether endotoxins are present, or whether the stated quantity is in the vial.

Purity versus identity

This is the distinction that matters. A sample can be 99% pure and be 99% pure something else.

Mass spectrometry confirms identity by measuring molecular weight. HPLC alone does not. A COA showing both is meaningfully stronger than one showing purity alone.

Quantity is separate again

Neither test tells you how much is in the vial. Underfilling is a common and hard-to-detect fraud precisely because the material that is present tests perfectly.

Whose certificate is it

A COA supplied by the seller, for an unspecified batch, with no traceable lab, is not evidence. What makes one meaningful is a batch number matching the product in your hand and a lab that can be identified.

Anything else is a document, not a test.

Why serialisation is stronger

A per-unit serial resolving to a manufacturer-side record is a check you can run yourself, on the specific unit you hold, not a claim about a batch you cannot connect to it. See verifying a SerenQ pen and spotting counterfeits.

What condition does to all of this

None of it survives bad handling. A verified, high-purity peptide that spent a week warm is degraded regardless of what any certificate said. See cold chain and warm delivery.

Supplied for research purposes only.