Biover Labs · September 3, 2026 · 3 min read
What Is a Certificate of Analysis (COA)?
A real COA is more than a purity number — it's a lab report tied to your exact batch. Here's what it should include, and the red flags that mean it isn't worth trusting.
A Certificate of Analysis — COA for short — is the document that's supposed to tell you what's actually in a vial. Not what the label says, not what the marketing copy claims: what independent lab testing actually found, for that specific batch. If you're buying research peptides and a supplier can't produce one, that's worth pausing on.
What a COA Actually Reports
A proper COA is a lab report tied to one specific production batch, or "lot." It typically includes:
| Section | What it tells you |
|---|---|
| Lot number | Which specific batch this document applies to |
| HPLC purity | Percentage of the sample matching the target compound |
| Mass spec (LC-MS) result | Confirms the molecule's identity by molecular weight |
| Appearance | Physical description (color, form) — a basic sanity check |
| Test date & lab name | Who ran the test, and when |
Some COAs go further, including net peptide content, endotoxin levels, or sterility results — especially relevant for peptides intended for sensitive lab applications.
Why the Lot Number Is the Whole Point
Here's the detail that separates a real COA from a marketing prop: it has to be tied to an actual batch number, matching the number printed on your specific vial. A document listing "typical results" with no lot number attached isn't testing your product — it's testing whatever sample the supplier felt like sending in, possibly once, possibly a while ago, and reusing that report indefinitely.
Batch-to-batch variation is real in peptide manufacturing. Different production runs can vary in purity, and without lot-specific testing, there's no way to know if the vial in front of you actually matches the document you were shown.
HPLC vs. Mass Spec: Why You Need Both
A lot of COAs only report one number — HPLC purity — and stop there. That's incomplete. HPLC tells you how pure the sample is relative to itself: what percentage of the detected material matches your target compound's retention time. It doesn't independently confirm what that compound actually is.
Mass spectrometry closes that gap. It measures the molecular weight of the sample, which either matches your target peptide's expected mass or it doesn't. Together, HPLC and mass spec answer two different questions — how pure, and what is it — and a COA missing either one is only giving you half the picture.
Independent Testing vs. In-House Testing
Who ran the test matters almost as much as what the test found. A supplier testing its own product in-house has an obvious incentive to report favorable numbers. Independent, third-party laboratories have no financial stake in the outcome, which is why their results carry more weight. When you're evaluating a COA, check whether the testing lab is named, and whether it's a recognizable independent facility rather than an in-house department of the seller. Bioverlabs, for example, sends every batch to Freedom Diagnostics, a US-based independent lab, and keeps the resulting COAs searchable by lot number.
Red Flags to Watch For
- A COA with no lot number, or one that doesn't match your vial
- "Typical results" language instead of batch-specific data
- Only a purity percentage, with no identity confirmation
- No named testing lab, or a lab that's clearly affiliated with the seller
- A COA that looks identical across multiple different products
The Bottom Line
A Certificate of Analysis exists to answer one question: does this specific vial contain what it claims to, at the stated purity? A credible COA is lot-specific, includes both HPLC and mass spec results, and comes from an independent lab. Anything less is closer to a marketing document than an actual quality record — and for research work where reproducibility depends on knowing exactly what you're working with, that distinction matters.