A Certificate of Analysis (COA) is a lab-issued document that reports a peptide’s identity and purity for a specific production batch. It is the single most useful piece of evidence when evaluating a research peptide supplier — because it lets you verify quality yourself instead of trusting a marketing claim.
This article is educational and for research use only. It makes no medical, therapeutic, or dosing claims.
What a COA actually tells you
A well-formed peptide COA answers four questions:
- Identity — is this the peptide it claims to be? (Confirmed by mass spectrometry.)
- Purity — what percentage is the target compound? (Measured by HPLC.)
- Batch — which production lot does this document describe?
- Method — how was it tested, and by whom?
Reading each section
HPLC purity
High-Performance Liquid Chromatography separates the sample into its components. The purity percentage is the area of the main peak relative to the total. A COA reporting 99.2% HPLC purity means the target peptide accounts for 99.2% of the detected material. Look for the chromatogram itself, not just a number.
Mass spectrometry
Mass spec confirms the molecular weight matches the expected peptide — this is the identity check. Identity “Conforms” plus a matching molecular weight is what you want to see.
Batch / lot number
Every COA should be tied to a batch number that also appears on the vial. This is what makes quality traceable — you can match the document to the physical product.
Why third-party testing matters
An in-house COA is better than nothing, but an independent third-party lab result carries far more weight, because the testing party has no incentive to inflate the number. At Certiva, every batch is tested by an independent lab, and we share the matching batch COA on request.
Related reading
Have a specific batch in mind? Start an inquiry and we’ll send the COA.
Frequently asked questions
What is a Certificate of Analysis for peptides?
A Certificate of Analysis (COA) is a lab-issued document reporting a peptide's identity and purity, typically verified by HPLC and mass spectrometry. It states the tested batch, purity percentage, and testing method so buyers can confirm quality independently.
What purity should a research peptide COA show?
Reputable research peptides typically report 98–99%+ HPLC purity. The COA should name the method (HPLC), show the chromatogram, and tie the result to a specific batch or lot number.
How do I know a COA is genuine?
A genuine COA is tied to a named third-party lab, a specific batch number, and a test date, and the supplier can produce the matching batch document on request. Cross-check the batch number on the vial against the COA.
For research use only. Not for human consumption. This article is educational and makes no medical, therapeutic, or dosing claims.