PeptideCompareVerification
What a real COA tells you — and what might be hiding in your peptides.
A Certificate of Analysis is only as good as the lab that issued it. Here is how to read one, which labs to trust, what to look for, and what contaminants are actually found in substandard peptides.
Key takeaways
- A COA is only as trustworthy as the independent lab that issued it — manufacturer self-tests prove batch consistency, not purity.
- HPLC measures purity but cannot confirm identity; LC-MS (mass spec) is what catches deliberate mislabeling.
- A complete COA shows identity, purity percentage, and an actual assay value in mg — not just one number.
- Verify the result on the lab's own server; a PDF alone is trivial to fabricate, and COAs over 12 months are treated as expired.
What is a COA?
A Certificate of Analysis (COA) is a document issued by an analytical laboratory confirming the composition and purity of a batch of product. For research peptides, a proper COA should include: identity confirmation (HPLC, LC-MS), purity percentage, actual assay content (mass in mg vs nominal), and ideally endotoxin and heavy metal testing.
COA red flags — how to spot a fake or weak COA
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Issued by the Chinese manufacturer — Not independent. The supplier tested their own product. Meaningful only for batch consistency, not purity verification.
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No identity test (only HPLC, no LC-MS) — HPLC measures purity but cannot confirm identity. LC-MS (mass spectrometry) confirms the molecule is actually what it claims to be. A COA without LC-MS cannot rule out deliberate mislabeling.
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No batch number or date — A COA without a specific batch number and test date is effectively generic. It may not correspond to the actual product you receive.
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No actual assay value (value mg) — A COA should state how many mg of active compound are actually present. A 10mg vial with 85% purity contains 8.5mg of active peptide. If the COA only shows 99% purity without an absolute mass, it's incomplete.
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More than 12 months old — PeptideCompare automatically marks COAs older than 12 months as expired. Peptides degrade. An old COA gives no information about the current batch.
Trusted independent labs
✓ JANOSHIK
Czech lab. Most commonly used by EU suppliers. Offers HPLC and LC-MS. Results available on their website with QR verification.
✓ LIQUILABS
Specialized in peptide and research compound testing. Known for thorough endotoxin testing. Used by 24Peptides — results verifiable online.
✓ VLAB
European accredited laboratory with ISO certification. Offers comprehensive peptide panels including heavy metals and microbial contamination.
✓ COLMAR / ROTTAPHARM
High-tier pharmaceutical-grade labs. COAs from these labs represent the highest standard of verification available in Europe.
What contaminants are actually found?
Wrong peptide (mislabeling) — Independent testing of gray market and low-tier vendors regularly discovers completely different peptides than labeled. A vial sold as "Retatrutide" may contain semaglutide or a generic compound.
Endotoxins (bacterial lipopolysaccharides) — Present in improperly manufactured peptides. Cause immune activation, fever, inflammation. The EU standard limit is <0.001 EU/mg.
Heavy metals (lead, arsenic, mercury) — Contamination from synthesis reagents or equipment. Can accumulate in tissue. Only detected with specific heavy metal panels.
Acetate/TFA salt content — Peptides are often synthesized with TFA (trifluoroacetic acid) as a counterion. Residual TFA at high levels is cytotoxic. Better suppliers use acetate salt forms or perform TFA removal.
Underdosing — A 10mg vial with only 6mg of active compound. Without an assay value on the COA, you would never know.
HOW PEPTIDECOMPARE USES COA DATA
Every COA in our database is reviewed by our team. We verify the lab, check the batch date, confirm the assay value exists, and flag any COA older than 12 months as expired. COA purity contributes 35% to our ranking score — it's the second-most important factor after price.
Sources
- Multifactor quality and safety analysis of semaglutide products sold by online sellers without a prescription. Journal of Medical Internet Research, 2024 — measured purity ran from 7.7% to 14.4% against a labelled 99%. www.ncbi.nlm.nih.gov
- Analysis of illegal peptide biopharmaceuticals frequently encountered by controlling agencies. Talanta / ScienceDirect, 2015 — the chromatographic methods customs and control agencies use on seized peptides. www.sciencedirect.com
- Click, click, buy: the market for novel synthetic peptide hormones on mainstream e-commerce platforms in the UK. ScienceDirect, 2023. www.sciencedirect.com