Certificates of Analysis — How to Read a Peptide COA
Certificates are published per production lot. Search the number printed on your vial.
Every lot Cytera releases is assayed by an independent laboratory before it goes on sale, and the certificate for that lot is published here. Not a sample document, not a representative example — the certificate for the exact batch in the vial you receive.
How to read a peptide COA
A certificate of analysis is only useful if you know what it does and does not cover. Most buyers read the purity line and stop, which is the one thing almost every supplier is willing to state.
| Purity (HPLC) | What percentage of the material is the peptide you ordered, measured by reversed-phase high-performance liquid chromatography and expressed as a share of total peak area. |
|---|---|
| Identity (MS) | Mass spectrometry confirming the molecular weight of the principal peak matches the claimed structure. Purity and identity are separate questions — material can be 99% pure and still be the wrong compound. |
| Lot number | Ties the certificate to one production batch. A certificate without a lot number cannot be matched to anything. |
| Date of analysis | When the assay was run. A certificate years older than the material tells you little about what is in the vial now. |
| Method | Which analytical method produced the result. Different methods are not interchangeable and are not directly comparable. |
What a purity figure does not tell you
These are the questions worth asking every supplier in this category, including us. We publish the first two today; the rest we are explicit about rather than silent on.
- Net peptide content. A lyophilised vial also contains counter-ions, salts and residual water. Net content is how much of the labelled mass is actually peptide — the number that determines real concentration after reconstitution.
- Endotoxin and sterility. Bacterial residue survives sterilisation and does not appear in a purity assay.
- Heavy metals. Trace lead, arsenic, mercury and cadmium can be introduced during synthesis. Detected by ICP-MS, not by HPLC.
If a supplier will not say which of these their certificate covers, that silence is itself an answer.
Scan the vial, not the website
Every Cytera vial carries a QR code that resolves to the certificate for its own lot. This matters because a COA page on a website can show anything — the useful test is whether the document you reach from the physical vial in your hand matches the batch printed on its label.
Third-party, not self-reported
Assays are run by an independent laboratory rather than by the manufacturer supplying the material. A manufacturer certifying its own output has an obvious interest in the result. Independent testing costs more and takes longer, and it is the only version of the claim that means anything.
The COA library
The library below is public — no account, no email address and no purchase required. Search the lot number printed on your vial. If the lot you hold is not listed, contact us with that number and we will provide the certificate directly.
Frequently asked
Can I see a COA before I buy?
Yes. The library is public and requires no account. We would rather you checked first.
What does ≥99% purity actually mean?
That at least 99% of the total peak area in the HPLC chromatogram corresponds to the target compound. It is a statement about that assay on that lot — not a claim about sterility, endotoxin load, heavy metals or net peptide content.
Why do different suppliers’ certificates look so different?
Because there is no mandated format for a research-chemical COA. That is precisely why the method, the lot number and the testing laboratory matter more than the headline percentage.
What if my lot number isn’t in the library?
Send us the number from the vial and we will provide the certificate. Every released lot has one.
For laboratory research use only. Certificates of analysis describe the composition of research materials. They are not a statement of safety or suitability for any use in humans or animals, and no product sold by Cytera Peptides is approved for such use.
Certificate library
No certificates are published yet
This library is live but not yet populated. We are not going to fill it with sample documents or representative certificates from other batches — a certificate that does not correspond to a real, tested lot is worse than no certificate at all, because it looks like verification while providing none.
If you are holding a vial and want its documentation, send us the lot number printed on the label and we will provide the certificate for that batch directly.