Research reference

How to Read a Certificate of Analysis

A Certificate of Analysis (CoA) is the primary batch documentation for research peptides. It confirms identity, purity, and release data for a specific lot — essential for reproducible laboratory work and audit trails.

What a CoA confirms

Each batch-specific CoA ties a physical vial lot to analytical results. At minimum, a peptide CoA should include:

• Batch / lot number — matches the label on your vial
• Product name and catalogue code — confirms the compound identity
• Sequence or chemical identity — where applicable for synthetic peptides
• Purity (%) — typically from HPLC area normalisation
• Molecular weight — often from mass spectrometry (MS)
• Net peptide content — gravimetric or calculated amount per vial
• Date of analysis and testing laboratory reference
• Storage conditions for lyophilised material

Reading purity results

Purity on a CoA usually refers to the main peak area as a percentage of total integrated peak area on a reverse-phase HPLC chromatogram. Impurities may include deletion sequences, truncated peptides, or oxidation products from synthesis. A specification of ≥99% means the main peptide peak accounts for at least 99% of detected material under the stated method.

Purity alone does not confirm identity — it must be read alongside MS data showing the expected molecular ion. See our purity standards guide for method detail.

Matching your vial to the CoA

Before use in any protocol, verify that the batch number printed on the vial label matches the CoA document. If you received multiple vials from one order, each may share a batch number but should still be cross-checked against the CoA issued for that dispatch.

Optimus Peptides provides batch CoAs on request — contact us with your order reference and vial batch number. See also our Quality & Testing page for our release process.

When to query a CoA

Request clarification from your supplier if:

• The batch number on the vial does not match the CoA
• Purity or molecular weight falls outside the stated specification
• The analytical method is not described or referenced
• Storage guidance is missing for lyophilised material

If a product fails to meet the specification on its CoA, our Returns Policy covers replacement or refund for verified specification failures reported within 48 hours of delivery.