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Research & Compliance

How do you verify peptide purity?

You cannot see purity, so how do you actually confirm it? The answer is learning to read the certificate of analysis and knowing which numbers matter.

5 min read Reviewed for accuracy Research Use Only
The short answer

You verify peptide purity by reading the certificate of analysis: check the HPLC purity percentage, confirm that mass spectrometry matches the expected molecular weight, and make sure the batch number on the COA matches the material you received.

The verification checklist

  1. Find the COA for your specific batch, not a generic sample.
  2. Check the HPLC purity percentage; a single dominant peak indicates high purity.
  3. Confirm the mass: mass spectrometry should match the peptide's expected molecular weight, confirming identity.
  4. Match the batch number on the COA to the number on your vial or label.
  5. Prefer third-party results, where an independent lab did the testing.
CERTIFICATE OF ANALYSIS Compound: Batch / Lot: Purity:99.4%+ Method: Date / Lab:
A certificate of analysis documents the compound, batch, measured purity, test method, and issuing lab.

Why each step matters

HPLC tells you how pure the material is; mass spectrometry tells you it is the right molecule; the batch match ties those results to what is actually in your hand. Skipping any one of them leaves a gap.

Browse research-grade peptides

Every Axis compound is third-party tested to 99.4%+ purity, with a certificate of analysis on every batch.

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Key takeaways

  • Verify purity by reading the batch-specific certificate of analysis.
  • Check HPLC purity percentage and look for a single dominant peak.
  • Confirm mass spectrometry matches the expected molecular weight.
  • Match the COA batch number to your vial; prefer third-party testing.

A note on research use

The peptides supplied by Axis Peptide Labs are reference compounds for laboratory and research use only. They are intended for qualified researchers working in academic, institutional, and analytical settings. They are not drugs, foods, cosmetics, or medical products, and they are not intended for human or veterinary consumption. Documented identity and documented purity are what matter most when sourcing a compound, both of which are published on the Axis certificates of analysis page.

Every compound is tested. Every certificate is public.

Browse the Axis Peptide Labs catalog of third-party tested research peptides, each with a published certificate of analysis.

Axis Peptide Labs supplies reference compounds for laboratory, academic, and institutional research only. All products are for research and identification purposes only. They are not for human or veterinary use, and are not a food, cosmetic, drug, or medical product. This article is educational and does not constitute medical, health, or usage advice.

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