A legitimate research peptide supplier publishes a lot-level Certificate of Analysis before purchase, reports both HPLC purity and mass-spectrometry identity, and links to the report on the testing lab's own site so it cannot be edited. A purity percentage with no chromatogram, no lot number, and no lab link is a claim, not a result.
A Documentation Checklist for Research Peptide Sourcing
Whichever supplier a lab buys from, the documentation should answer these questions before the order:
- Is the COA public before purchase? A certificate available only after the sale — or on request — can't inform the sourcing decision.
- Is it lot-level? A "representative" certificate describes a past batch, not the vial being shipped. Look for a certificate tied to the lot number.
- Does it include both purity and identity? HPLC purity alone shows one dominant peak — it doesn't confirm the peak is the named compound. Mass spectrometry identity confirmation closes that gap.
- Can the certificate be verified with the lab? A PDF is easy to edit. A link to the report on the testing lab's own site is not.
- Is compound identity data sourced and checkable? CAS numbers and molecular weights should trace to a primary registry (PubChem), not to another vendor's product page.
- Is the research-use-only boundary stated? Research chemicals should be labeled and sold for laboratory use only, with that boundary stated on the product itself, not buried in terms.
How Peptide Hackers Answers Each
Our COA library is public and lot-level; certificates report HPLC purity and measured quantity, with identity results on the Accumark certificates; each page links to the lab's own copy of the report; reference identity data is PubChem-verified; and everything we sell is for laboratory research use only.
A worked example: our VIP certificate copies Accumark Labs report EUKK-2QL4 (lot AM20260925-23, analysis completed September 29, 2026) — purity 99.013% against a > 98.0% specification, identity VIP (Conforms), measured quantity 9.105 mg — and links to the same record on accumarklabs.com. The step-by-step check is in How to verify an Accumark COA.
Details on the methods behind each certificate are in our analytical techniques overview, and the standards we hold documentation to are described on our quality standards page.
Questions buyers ask
How can I tell if a peptide vendor's purity claims are real?
Ask for the lot-level Certificate of Analysis and open the report on the testing lab's own website, not a PDF. A real result shows the chromatogram, the lot number that matches your vial, the analysis date, and an identity result — not just a percentage.
What should a peptide Certificate of Analysis include?
The product name, the lot number, HPLC purity against a stated specification, a mass-spectrometry identity result, the analysis date, the lab's name, and a way to verify the report with the lab directly.
Is HPLC purity alone enough?
No. HPLC purity shows one dominant peak; it does not confirm the peak is the named compound. Mass-spectrometry identity confirmation closes that gap, so a certificate should report both.
Why does lot-level testing matter?
A "representative" certificate describes a past batch, not the vial being shipped. Only a certificate tied to the lot number on your vial describes what you received.
Where should CAS numbers and molecular weights come from?
A primary registry such as PubChem, not another vendor's product page. Registry-sourced identity data can be checked; copied data cannot.
Research Use Only
All products referenced are for laboratory research use only, not for human or veterinary use. This material is educational and does not constitute sourcing, procurement, or regulatory advice.