How to read a peptide certificate of analysis

A certificate of analysis is the document that turns a claim into evidence. Every research batch should have one, and it should be issued by a laboratory independent of the seller. Here is how to read one quickly.

1. Identity

Mass spectrometry confirms the molecule in the vial is the molecule on the label by matching the observed mass to the theoretical mass of the sequence. Check that the compound name, sequence or molecular formula, and observed mass are all present and consistent with each other.

2. Purity

HPLC separates the sample into peaks and reports the main peak as a percentage of total area. Look for the stated purity figure, the method used, and whether a chromatogram is attached. A number with no trace behind it is an assertion, not a result.

3. Lot traceability

• The lot number on the COA must match the lot printed on the vial you hold.
• The test date should sit close to the manufacturing date for that lot.
• The issuing laboratory should be named, not anonymised.

4. What a missing field tells you

Absent method details, an unnamed lab, or a document that covers a different lot than the one in front of you are all reasons to ask before you use the material. Opa Peptides supplies batch documentation, independent identity and purity testing, and lot references on request for any catalog item — ask by email and reference the lot on your vial.

Research use only. Nothing here is medical guidance or a claim about any outcome.