A Certificate of Analysis (COA) is the single most important document when evaluating a peptide vendor. It's the paper trail between a manufacturer's claims and independent verification. Yet most buyers don't know how to read one. This guide breaks it down.
What a COA Should Include
- Product name and lot/batch number
- Testing laboratory name and accreditation (look for ISO 17025)
- Test date (should be recent — within 12 months of purchase)
- HPLC purity result (High-Performance Liquid Chromatography)
- Mass spectrometry (MS) confirmation of molecular identity
- Amino acid composition or sequence confirmation
- Moisture content and residual solvent analysis (for lyophilized peptides)
The Most Important Number: HPLC Purity
HPLC purity tells you what percentage of the sample is actually the peptide you ordered. Everything else is impurities — which could be related peptide fragments, synthesis byproducts, or in worst cases, entirely different compounds.
- ≥99% purity — pharmaceutical grade, ideal for sensitive research
- ≥98% purity — research grade, acceptable for most applications
- 95–98% purity — lower grade, use with caution
- Below 95% — do not use for any serious research application
Mass Spectrometry: Confirming Identity
HPLC tells you how pure the sample is, but mass spectrometry (MS) tells you what it actually is. A COA with both HPLC and MS data is significantly more trustworthy than one with HPLC alone. Look for the reported molecular weight to match the theoretical molecular weight of the compound within a small margin (typically ±0.5 Da).
Red Flags to Watch For
- No third-party lab — in-house testing only means the vendor is grading their own work
- No lab name or accreditation on the COA
- COA older than 18 months — peptides degrade, testing should be recent
- Purity reported without a specific method (HPLC, MS, etc.)
- Generic COA not tied to a specific batch number
- COA available only on request — reputable vendors post them publicly
How Aura Protocols Vets Vendors
Every vendor we feature on Aura Protocols must provide publicly accessible, batch-specific COAs from accredited third-party laboratories. We manually review these documents before listing any product. If a vendor's documentation doesn't meet our standards, they don't appear on this site — regardless of commission rates.
When in doubt, email the vendor and ask for the COA for the specific batch you're purchasing. A trustworthy vendor will respond promptly with complete documentation.
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