What Is a COA?

A Certificate of Analysis is a document from an analytical laboratory that verifies the identity, purity, and quality of a peptide. Legitimate COAs are produced by third-party testing labs (not the vendor themselves) and contain specific analytical data including HPLC chromatograms, mass spectrometry results, and purity percentages.

Key Sections of a COA

Section	What It Shows	What to Look For
Product Identity	Peptide name, sequence, molecular weight	Verify matches what you ordered
Batch/Lot Number	Unique identifier for the production batch	Should match the label on your vial
Purity (HPLC)	Percentage purity via chromatography	Research grade: ≥98%. Acceptable: ≥95%
Mass Spec (MS)	Molecular weight confirmation	Observed MW should match theoretical MW
Appearance	Physical description of peptide	Usually “white lyophilized powder”
Testing Lab	Name of analytical laboratory	Should be third-party, not in-house
Date	When testing was performed	Should be recent and match batch

Understanding HPLC Results

High-Performance Liquid Chromatography (HPLC) is the gold standard for peptide purity testing. The HPLC chromatogram shows peaks representing different compounds in the sample. The main peak represents your target peptide, while smaller peaks indicate impurities.

• ≥99% purity: Pharmaceutical grade — highest quality available
• ≥98% purity: Research grade — standard for quality vendors
• 95-97% purity: Acceptable for many research applications
• <95% purity: Below standard — significant impurities present

Understanding Mass Spec Results

Mass spectrometry confirms the molecular identity of the peptide by measuring its molecular weight. The observed molecular weight should closely match the theoretical molecular weight for the peptide sequence. A match confirms you have the correct peptide, not a substitution or degradation product.

• Exact match (±0.5 Da): Strong confirmation of identity
• Close match (±2 Da): Acceptable, may reflect instrument calibration
• Significant deviation (>5 Da): Potential identity issue — investigate further

Red Flags to Watch For

• No batch number: Generic COAs not tied to specific batches are meaningless
• In-house testing only: Vendor-generated COAs without third-party verification
• Missing chromatogram: A purity number without the HPLC graph is unverifiable
• Reused COAs: Same COA document used across different batch numbers
• No lab name: Legitimate COAs identify the testing laboratory
• Old dates: COA dates that don’t align with the batch production timeline
• Round numbers: Suspiciously consistent “99.9%” across all products

How to Verify a COA

1. Check the lab: Search for the testing laboratory name online. Verify it’s a real analytical lab.
2. Match batch numbers: The COA batch number should match the label on your vial.
3. Review the chromatogram: Look for a clean main peak with minimal secondary peaks.
4. Verify molecular weight: Compare the observed MW to the known MW for that peptide sequence.
5. Contact the lab: Some labs will verify COA authenticity if you provide the batch number.

Vendors with Best COA Practices

Based on our research, these vendors consistently provide verifiable, batch-specific third-party COAs:

Vendor	COA Quality	Third-Party	Batch-Specific	Link
Swiss Chems	Excellent	Yes	Yes	Visit →
Peptide Sciences	Excellent	Yes	Yes	Visit →
Amino Asylum	Good	Yes	Yes	Visit →

Frequently Asked Questions

What does COA stand for?

COA stands for Certificate of Analysis. It is a document from an analytical laboratory that verifies the purity, identity, and quality of a peptide product through standardized testing methods.

Should I trust vendor-provided COAs?

Only if they are from a third-party laboratory and batch-specific. In-house COAs or generic documents without batch numbers should be viewed skeptically. Reputable vendors use independent labs.

How often should COAs be updated?

Every production batch should have its own COA. If a vendor uses the same COA for months or years, it likely does not reflect the actual quality of your specific purchase.