A Certificate of Analysis is only useful if you can read it. Here is line-by-line what a legitimate peptide COA reports and what each field means.
A Certificate of Analysis (COA) is the primary document verifying that a peptide batch matches its declared identity and purity. This reference walks through each COA field a research lab evaluates before releasing the material into an experiment.
Field-by-field reference
| Field | What it should report |
|---|---|
| Batch / lot identifier | Unique per production run, traceable to the lot record |
| Synthesis date | Anchors shelf-life and stability documentation |
| HPLC purity (%) | Typically ≥98% for research; ≥99% for peptides under ~30 residues |
| Analytical HPLC method | Column, mobile phase and gradient specified |
| LC-MS identity | Observed mass within ±0.5 Da of theoretical |
| Counterion | Acetate or TFA, with percent by mass |
| Water content | Karl Fischer or TGA result |
| Endotoxin | Where downstream cell culture is involved |
Common COA red flags
- Purity reported without a supporting HPLC chromatogram image.
- Mass reported without a supporting LC-MS trace.
- No counterion or water-content data.
- Boilerplate batch numbers reused across shipments.
Research use only. All information on this page is provided strictly for in-vitro and laboratory research reference. Nothing in this article is medical, therapeutic, dosing, or performance advice for human or veterinary use.
