What is a Certificate of Analysis?

A Certificate of Analysis (COA) is a third-party lab report certifying peptide purity, identity, and composition. It typically includes HPLC (purity %), mass spectrometry (molecular weight confirmation), and batch traceability. A valid COA is the primary tool to verify peptide authenticity.

How do I spot a counterfeit peptide vial?

Red flags include: misaligned or blurry labels, unsealed caps, discoloration or crystallisation inside the vial, mismatched batch numbers between vial and COA, vials without lot numbers, and no accompanying documentation. Authentic suppliers ship sealed, lot-numbered vials with matching paperwork.

What purity level is acceptable for research peptides?

Standards vary by application. Most research-grade peptides are >95% pure by HPLC. High-end suppliers provide >99% purity. For sensitive in-vitro or in-vivo work, >98% is recommended. Always check the COA and confirm purity meets your experiment's needs.

Can I verify a COA's authenticity?

Yes. Cross-reference the COA's lab accreditation (look for ISO 17025 certification), verify the supplier's logo and contact details, and contact the lab directly if authenticity is uncertain. Ask the supplier for references or third-party validation, and compare COA formatting against known legitimate samples.

Research Compounds · Quality Control · Supplier Vetting

Peptide Sourcing & Verification Guide: How to Spot Counterfeit Peptides

Published Jun 4, 2026 · New-U Team · 7 min read

Quick answer: Verify peptide authenticity by: (1) reviewing the Certificate of Analysis (COA)—check HPLC purity >98%, batch number matching, third-party lab accreditation (ISO 17025); (2) inspecting the vial—sealed cap, clear label, matching lot number; (3) confirming supplier credentials—company registration, transparent ordering, customer references; (4) testing if needed—HPLC, LCMS, or mass spectrometry. Counterfeit peptides are common; reputable suppliers provide full documentation and are transparent about manufacturing and testing.

The Certificate of Analysis: Your Primary Verification Tool

The COA is a third-party lab document certifying peptide identity and purity. Every legitimate supplier includes a COA with each batch. Here's what to verify:

HPLC purity: Should be >95%, ideally >98%. Lower purity indicates impurities or degradation.
Batch number match: The COA batch number must match the label on your vial. Mismatches indicate substitution or fraud.
Lab accreditation: Look for ISO 17025 (international lab accreditation) or equivalent. Unknown labs lack credibility.
Molecular weight confirmation: The COA should confirm peptide identity via mass spectrometry (MS) or LCMS.
Date issued: Recent COAs (within the past year) suggest fresh material. Very old COAs may indicate warehouse age or degradation.
Lab contact details: Legitimate labs list contact info. Cross-verify with the supplier if uncertain.

Vial Inspection Checklist

Physical inspection catches obvious counterfeits and damaged goods:

Seal integrity: Cap should be tamper-evident and sealed. Any loose or broken seal is a red flag.
Label clarity: Labels should be legible, aligned, not blurry or hand-written.
Lot number: Vial must have a printed lot/batch number. No lot number = high risk.
Peptide appearance: Lyophilised powder should be white to off-white. Yellowing, discoloration, or liquid leakage indicates degradation or contamination.
Label-COA match: Cross-reference peptide name, concentration, mass, and lot number between vial label and COA.
No off-odours: When vial is opened, peptide should have minimal odour. Strong ammonia or decay odours suggest contamination.

Supplier Vetting: Five Key Questions

Is the supplier registered and legitimate? Check business registration, website SSL certificate, address verification, and years in operation.
Are they transparent about sourcing and testing? Reputable suppliers explain manufacturing origin, quality control processes, and testing methods.
Do they provide detailed COAs? Each batch should include a COA with full documentation. Suppliers without documentation are unreliable.
Do they offer customer references or independent reviews? Ask for research institutions or known customers that vouch for product quality.
Is there a clear customer support and return policy? Legitimate suppliers stand behind their product and address quality issues promptly.

Common Red Flags: Counterfeit Peptides

Vials with no batch numbers or mismatched batch numbers between label and COA.
Illegible or hand-written labels.
Prices significantly lower than market—often indicates low purity, contamination, or fake product.
Suppliers with no verifiable business address, phone number, or customer support.
Vague or missing COAs; COAs with incomplete information (no HPLC % purity, no lab name).
Lab names on COAs that cannot be verified independently.
Delivery in plain packaging with no indication of contents.
Suppliers who refuse to provide detailed COAs or batch information.
Lyophilised peptides with visible discoloration, liquid, or crystallisation.

If You Suspect Counterfeit Peptides

Contact the supplier immediately with documentation (photos, batch number, COA). Request investigation or replacement.
Verify the COA independently: Call the lab listed on the COA and confirm the batch details match the lab's records.
Request re-analysis: Ask the supplier to re-test the peptide with an independent lab. Legitimate suppliers accommodate this request.
Consider testing yourself: If the research is critical, send a sample to an independent HPLC or LCMS lab for purity verification (~$200–500).
Report to regulatory bodies (FDA, state pharmaceutical boards) if you believe fraud is occurring.