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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One COA for several batches — A genuine report can still be misused. Identical results across supposedly independent batches, or a report that does not match the batch on your vial, prove nothing about what you received. Check that every page belongs to the same sample, and whether the report covers bulk material or the filled vials.
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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.
What a complete report looks like
Adria Science published a KPV report as a worked example (10mg vial, batch 2027602, tested by Liquilabs). It shows what a full report contains — and what it still leaves out.
Content — 10.48mg measured in a vial labelled 10mg (104.8% of nominal), by HPLC with external-standard calibration.
Purity — >99.8% by HPLC, using area normalisation. That is the share of the main peak, not proof that nothing else is present.
Identity — confirmed by FTIR and by retention time.
Endotoxins — tested with the chromogenic method (USP <85>, European Pharmacopoeia 2.6.14).
Not covered — sterility, residual solvents and elemental impurities. The results apply only to the sample that was tested.
A QR code, certificate number or unique verification code that lets you check the result on the lab's own server is the only real check — a PDF on its own proves nothing. And 99% purity by itself says nothing about identity, content, endotoxins, heavy metals or microbiological quality (total aerobic microbial and yeast-and-mold counts).
Trusted independent labs
✓ JANOSHIK
Czech lab, the most widely used by EU and international suppliers. Offers HPLC purity, mass-spec identity and content analysis, with results verifiable online via a key or QR code. Supports both individual and group testing, and publishes a public results database.
✓ UZORAK
EU-based lab (Croatia) focused on peptide analysis by high-resolution LC-MS, going beyond basic mass and purity. A European option for researchers who want identity and purity confirmation close to home.
✓ LIQUILABS
Czech laboratory offering a comprehensive peptide panel: content and purity by HPLC-UV/HPLC-MS, high-sensitivity endotoxin testing, bioburden (microbial) analysis, and heavy-metal determination by ICP-MS/AAS against ICH Q3D limits.
✓ FINNRICK
US-based independent platform that tests samples for free and publishes vendor rankings openly. Less a private-COA service than a transparency engine — by aggregating thousands of results it exposes consistency (and its absence) across vendors.
✓ FREEDOM DIAGNOSTICS
US lab (Tennessee) known for fast turnaround and a large, publicly searchable COA database. Pairs HPLC purity with LC-MS identity on every certificate as a matter of policy — never one without the other.
✓ CHROMATE
US analytical service focused on affordable supplement and compound analysis, with an "unannounced testing" project that buys and tests products off the shelf to keep manufacturers honest. Literature-based methodology at accessible prices.
Two articles from Adria Science: Peptide Certificate of Analysis: How to Verify a COA and Identify Authentic Laboratory Reports · KPV COA report, batch 2027602
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
- Peptide Certificate of Analysis: How to Verify a COA and Identify Authentic Laboratory Reports. Adria Science, 14 September 2026 — batch matching, verification codes and red flags such as one report reused across batches. adriascience.com
- KPV COA report, batch 2027602 (report LYO-0791, Liquilabs). Adria Science, 8 September 2026 — assay 10.48mg on a 10mg vial, purity above 99.8%, endotoxin testing by the chromogenic method. adriascience.com