Research Library · Methods Guide
How to Read a Certificate of Analysis (COA) for Research Peptides
A Certificate of Analysis (COA) is a document, produced by an analytical laboratory, that reports the measured identity and purity of a specific batch of a compound. For research peptides, a COA is the single most important document for evaluating what you actually received - it is the difference between a vendor that says a product is pure and one that can prove it, batch by batch. Learning to read a COA lets any researcher verify a compound before relying on it in an experiment. At AurexBioLabs, every batch ships with a COA, and you can download and view the true lab COA as a PDF for your specific lot through our verification page.
For Research Use Only. Not for human or veterinary use. Not a drug, food, or cosmetic. This page is educational reference material for qualified researchers and contains no medical advice, dosing, or health claims.
The Key Sections of a Peptide COA
1. Product & Batch Identification
At the top, a COA identifies the product name, the batch or lot number, and often a manufacture or test date. The lot number is critical: a COA is only valid for the exact batch it names. Always confirm the lot number on the COA matches the lot printed on your vial label.
2. HPLC Purity (%)
High-Performance Liquid Chromatography (HPLC) measures purity - the percentage of the sample that is the intended peptide versus impurities. On the COA you'll see a reported purity percentage (research-grade peptides are commonly reported at 98%+ or 99%+) and usually an HPLC chromatogram: a graph with a large primary peak (your peptide) and minimal secondary peaks (impurities). A single dominant, sharp peak indicates high purity; multiple large peaks indicate a less pure sample.
3. Mass Spectrometry (Identity)
Mass Spectrometry (MS) confirms identity - that the compound is actually the peptide it claims to be. The COA reports the observed (measured) molecular weight and compares it to the theoretical (expected) molecular weight for that peptide. When the observed mass matches the theoretical mass, identity is confirmed. This is why the molecular-weight figures on a product page matter: they're what the MS result is checked against.
4. Physical Description & Additional Tests
Many COAs also note the physical appearance (e.g. white lyophilized powder), and some include tests such as water content, acetate content, or peptide content, which further characterize the material.
How to Tell a Real COA From a Fake or Generic One
Signs of a credible COA:
- It names the specific batch/lot number - not a generic or missing lot.
- It shows the actual HPLC chromatogram and MS spectrum, not just a claimed number.
- It comes from a third-party or clearly identified analytical lab.
- The observed mass matches the theoretical mass for that peptide.
A "COA" that is just a number with no chromatogram, no lot number, or no lab identification provides little real assurance. This is exactly why AurexBioLabs publishes the full lab PDF COA for each batch rather than a summary figure.
Download & View the True Lab COA (PDF)
- Locate the lot / batch number printed on your vial label.
- Go to the AurexBioLabs verification page.
- Enter your lot number to view and download the full Certificate of Analysis PDF for that exact batch - including the HPLC and mass-spectrometry results.
This lets you independently confirm the purity and identity of the material in your hands.
Frequently Asked Questions
It reports the measured identity (via mass spectrometry) and purity (via HPLC) of a specific batch of a compound.
Research-grade peptides are commonly reported at 98%+ or 99%+ HPLC purity, shown as a dominant single peak on the chromatogram.
It measures the compound's molecular weight and compares it to the theoretical weight for that peptide; a match confirms identity.
Enter the lot number from your vial label at our verification page to download the full lab COA PDF for that batch.
A COA is only valid for the exact batch it names - always match the COA lot number to the lot on your vial.
Next Steps
Verification & catalog
For Research Use Only. Not for human or veterinary use. Not a drug, food, or cosmetic. This page is educational reference material for qualified researchers and contains no medical advice, dosing, or health claims.
AurexBioLabs supplies research compounds for laboratory research use only. Not for human or veterinary use, diagnostic, or therapeutic purposes.