The COA, honestly

A Certificate of Analysis is the single most useful document a peptide vendor can publish — and one of the easiest to misunderstand. Here's what it actually tells you, what it can't, and exactly how pepmg treats it.

▸ What a COA is

A COA is a lab's report on a specific batch of material. For research peptides it usually reports two things:

• Identity — is this molecule actually the peptide on the label? Confirmed by mass spectrometry (the measured mass matches the peptide's theoretical mass).
• Purity — what fraction of the sample is the intended peptide vs. truncated chains, byproducts, or residual solvents? Measured by HPLC and reported as a percentage (research-grade is typically ≥98%).

Some COAs add mass/quantity (does the vial contain the labeled milligrams?) and tests for specific contaminants. That's the useful core: identity, purity, quantity.

▸ What a COA does not prove

• Not your vial. A COA covers the batch that was tested. The vial you receive is only as represented as the vendor's batching and honesty make it.
• Not safety, and not fitness for any use in humans. Purity is not approval. These are laboratory reference materials.
• Not un-fakeable. A PDF can be edited; a template can be reused. This is the important one, and it's why we do not claim to detect "fake" or "AI-generated" COAs — no honest tool can. Instead we look at something checkable: who is standing behind the document.

▸ The one thing that raises a COA above "trust me"

A COA is only as credible as the party that can confirm it. That's why where the results live matters more than how official the PDF looks:

• Lab-hosted — the results are viewable on the testing lab's own site (e.g. Janoshik), where the lab itself stands behind them. This is the strongest public signal a buyer can get without commissioning their own test.
• Self-hosted, lab named — a real third-party lab is named, but the documents live on the vendor's own site. Plausibly genuine; not something the lab confirms for you.
• Unattributed — COA-style documents with no testing lab named. Weakest published tier.
• None — no COA presence found.

These are exactly the tiers pepmg detects automatically and folds into each vendor's transparency score. Ranking is still $/mg only — a COA can lift a vendor's trust score and badges, never its price rank.

▸ Reading one yourself — a 30-second checklist

• Does the peptide name and sequence on the COA match what you're buying?
• Is there a mass-spec result, and does the measured mass match the peptide's expected mass?
• Is HPLC purity stated as a number (not just "passed"), and is it ≥98%?
• Is there a batch/lot number and a date — and does the lot tie to the product you're ordering?
• Is a testing lab named, ideally one whose results you can look up independently?

▸ pepmg's stance, in one paragraph

We link what vendors publish and we classify how verifiable it is (lab-hosted > self-hosted > unattributed). We do not run the labs, we do not test the material, and we do not certify purity or authenticity — anyone who tells you they can verify a peptide's purity from a web page is selling something. What we can do is make the published evidence easy to find, honestly labeled, and impossible to buy your way up the ranking with. The rest — vetting a source before you buy — is genuinely yours to do, and we've tried to make that call as informed as we honestly can.

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