How to Read a Peptide Certificate of Analysis

Research purchasing guide · Updated 13 September 2026

A Certificate of Analysis (COA) helps you assess a particular material against the tests reported for it. Read the complete document alongside the product listing before choosing a research peptide. A headline purity percentage is only one part of that assessment.

1. Match the report to the material

Compare the compound name, batch or lot number, sample identifier and report date with the information supplied for the product. Similar names or matching strengths do not establish that two documents refer to the same batch. Ask about missing or inconsistent references before relying on a report. Keep the document with your laboratory purchasing record.

2. Check what was measured

Read the test name, method, units and result together. Identity, purity and quantity are different questions; interpret each result according to the property and method stated in the report.

For certified reference materials, NIST describes certificates as identifying the material and intended use, methods, certified values, uncertainty and relevant use or storage information. This provides useful context for document review; it does not make a commercial research peptide a NIST-certified reference material. Source: NIST reference-material definitions.

3. Put purity in context

Check what a percentage represents and which impurities the method addresses. A chromatographic percentage is not a complete account of every component, nor an independent measurement of the amount in a vial.

The IUPAC technical report hosted by NIST discusses different approaches to assigning organic-compound purity, including mass balance and quantitative NMR, and considers water, volatile components and related impurities. The measurement method and basis therefore matter when interpreting the result. Source: IUPAC technical report on organic-compound purity.

4. Read the limitations and report status

Check whether the document is final, current and applicable to the material supplied. A document marked “sample”, “example” or “not a valid lab report” cannot establish that the purchased batch was tested. Do not infer tests or results the document does not contain. A COA is not permission to use a research-only product in people or animals.

5. Consider traceability

If your laboratory requires traceable measurements, review the calibration and reference information supporting the result. Eurachem explains analytical traceability and links to detailed guidance. Assess whether the evidence suits the intended measurement and your laboratory’s requirements. Source: Eurachem analytical-traceability guidance.

Before ordering: five checks

• Does the document identify the correct material and batch?
• Are the methods, units and results clear?
• Is the report final and applicable to the material supplied?
• Are missing tests or limitations relevant to your protocol?
• Have you checked the product’s contents and storage information?

For professional laboratory research only, not human or veterinary use. Sources provide general scientific guidance; their inclusion does not imply endorsement or certification of products sold here.