How to Read a Peptide Certificate of Analysis (COA)

Every legitimate peptide supplier should provide a Certificate of Analysis (COA). Here’s how to read one critically.

What a COA Should Contain

A complete COA includes:

  1. Product name and batch number — for traceability
  2. Synthesis date and expiration date
  3. Appearance — typically “white lyophilized powder”
  4. HPLC purity — the main purity metric
  5. Mass spectrometry — molecular weight confirmation
  6. Chromatogram — visual proof of purity
  7. Storage conditions
  8. QC stamp or signature

Reading HPLC Chromatograms

The chromatogram is the heart of a COA. Key things to check:

  • Single dominant peak — should be ≥98% of total area
  • Sharp peak shape — no shoulder peaks (indicates impurities)
  • Retention time consistency — matches reference standard
  • Baseline flat — no drifting (indicates column issues)

Red Flags

Watch out for:

  • Multiple peaks close to the main peak (degradation products)
  • Broad or tailing peaks (poor purification)
  • Missing chromatogram entirely (just a number with no proof)

Understanding Mass Spectrometry

Mass spec confirms molecular identity:

  • Observed mass should match calculated mass within 0.1%
  • Example: For a peptide with calculated mass of 4115.7 Da, you should see a peak at 4114.7-4116.7
  • A single dominant [M+H]+ peak confirms correct sequence
  • Multiple peaks may indicate salt forms or adducts (acceptable)

Common Scams to Avoid

🚩 COA with no chromatogram image 🚩 Different batch number on COA vs. vial 🚩 Lab name not verifiable 🚩 Purity claim >99.9% (almost impossible for 30+ AA peptides) 🚩 “HPLC” without showing the method or column

Jike Bio’s COA Standard

Every Jike Bio shipment includes:

  • ✅ HPLC chromatogram (image + numeric)
  • ✅ Mass spec result
  • ✅ Third-party lab verification
  • ✅ Batch traceability

Trust, but verify. Always request and inspect the COA.