What a CoA is
A Certificate of Analysis (CoA) is the test record for one production lot. It lists the tests run on samples from that lot, the method used for each, the acceptance limit set before testing, and the result. A CoA applies only to the lot number printed on it, not to the product in general.
A useful CoA answers three questions: is this the right compound (identity), how much of what's in the vial is that compound (purity and content), and is the lot free of contamination that would interfere with lab work (endotoxin).
The header block
Before the results, check the header. It should identify:
- Product and strength, e.g. BPC-157, 10 mg per vial.
- Lot number, which must match the label on your vials. PepDistro lots follow the format PD-YYMM-NNNN.
- Test or report date, which should fall after the manufacture date.
- Testing laboratory, by name, so you can contact it.
- Approval: who reviewed and released the result.
The results table
Most peptide CoAs use four columns: the test, the method, the specification and the result. The specification is the pass/fail limit, set in advance. The result is what this lot measured. A lot passes when every result falls inside its specification.
| Test | What it answers | Typical method | PepDistro specification |
|---|---|---|---|
| Identity | Is it the right molecule? | Mass spectrometry | Conforms to theoretical mass |
| Purity | What share of the material is the target peptide? | RP-HPLC, UV 214 nm | ≥ 98 % |
| Content | How much peptide is in the vial vs. the label? | HPLC assay vs. reference standard | Label ± 10 % |
| Endotoxin | Is bacterial endotoxin below the limit? | LAL, kinetic chromogenic | ≤ 5 EU/mg |
| Appearance | Does the powder look as expected? | Visual | White to off-white (GHK-Cu: blue) |
Purity and content are different numbers
Purity is a ratio: the area of the main HPLC peak as a share of all peaks detected. It says nothing about how much material is in the vial. A vial can be 99 % pure and still hold less than its label states.
Content (sometimes called assay or net peptide content) measures the quantity against the label claim. Lyophilized peptides also carry water and counter-ions such as acetate, so the weight of powder is not the same as the weight of peptide. A CoA that reports purity but no content leaves that question open.
How to check a CoA
- Match the lot. The lot number on the CoA must match the vial label exactly.
- Check the dates. Testing should postdate manufacture, and the report should be recent enough to cover the lot you received.
- Confirm the lab. The CoA should name the testing lab. You can contact the lab and ask it to confirm the report number.
- Look for the data behind the numbers. A chromatogram and mass spectrum make a purity or identity claim checkable.
- Compare the specification. Know the limit each result is judged against, not just the result.
Red flags: a CoA with no lot number, the same CoA used for every lot, results with no method or specification, or a lab that can't be identified.
How PepDistro handles CoAs
Every PepDistro vial carries a QR code that opens the CoA for its lot. Each lot is tested by an independent third-party lab, named on the certificate. You can also enter a lot number on the CoA lookup page.