A Certificate of Analysis (COA) is the document that tells you what’s actually in a peptide vial. For reproducible research, it’s the single most important piece of paperwork. This guide explains what a COA reports and how to read one.
- What it is: a lab report on a specific batch’s identity and purity.
- Key tests: mass spectrometry (identity) and HPLC (purity).
- Why it matters: two vials labeled the same can differ in purity.
- Tip: a COA should be batch-specific, not generic.
What a COA reports
| Field | What it tells you |
|---|---|
| Product & batch | The exact compound and lot the report covers. |
| Identity (MS) | Mass spectrometry confirms the molecule is what’s claimed. |
| Purity (HPLC) | The percentage that is the intended peptide. |
| Sequence | The amino-acid sequence analyzed. |
| Test date | When the analysis was performed. |
How to read a COA
- Match the batch. The lot number on the COA should match the vial.
- Check identity first. Mass spec should confirm the expected molecular weight.
- Read the HPLC purity. Higher is better; look for the reported percentage and the chromatogram.
- Note the method. A credible COA names the techniques and conditions used.
Why it matters
Peptide synthesis is precise but never perfect, so finished material can carry trace by-products. The COA is how you verify that purification worked and that you know exactly what you’re working with. To understand the purity number itself, see our guide to peptide purity and HPLC testing, and for background, how peptides are made.
Research use only. For educational purposes. Compounds referenced are not approved for human or veterinary use, and nothing here is medical advice. Sold strictly for in vitro laboratory research by qualified professionals.
Every batch we sell is purity-verified
Lab-tested with third-party Certificates of Analysis.