A certificate of analysis (CoA) is the document that tells you what's actually in a vial of research peptide. A meaningful one is batch-specific — tied to the exact lot you received — not a generic marketing sheet. This guide runs through each field, what a strong CoA looks like, and the red flags of a weak or generic one. For qualified researchers; all material is for in-vitro research use only.
The fields a CoA should have
- Product name & batch/lot number — must match the label on your vial. If it doesn't, the document says nothing about your material.
- Identity (mass spectrometry) — the observed mass alongside the theoretical mass from the sequence. A match confirms the right molecule; it's the single most important check, and the one most often missing.
- Purity (HPLC) — a percentage (e.g. ≥99%) and the chromatogram. The number is easy to assert; the trace is the proof.
- Net peptide content — the real peptide fraction of the powder. Because synthetic peptides hold water and counter-ions, a "5 mg" vial rarely holds 5 mg of pure peptide. Found by amino-acid or nitrogen analysis.
- Water content — usually Karl Fischer titration.
- Counter-ion — acetate or trifluoroacetate (TFA) salt content, measured by ion chromatography/HPLC.
- Appearance & test date — e.g. white lyophilised powder, plus the date of analysis.
What a strong CoA looks like
A good CoA shows both identity and purity with the data behind them (the MS spectrum and the HPLC chromatogram), carries the same batch number as your vial, and reports net peptide content so you know the real quantity. For how those tests work, see our reference on research peptide purity & testing.
Red flags
- No batch number, or one that doesn't match your vial — the document isn't about your material.
- A purity figure with no chromatogram — an unverifiable claim.
- No mass-spec identity — purity without identity tells you a sample is clean, not that it's the right compound.
- The same CoA on every order — a real one is generated per batch.
- No net peptide content — you can't know the true quantity.
How to request one
Every batch we list carries a traceable batch number and an HPLC/MS certificate of analysis, available on request — see quality & testing, or browse the catalogue.
Research use only. Everything referenced here is supplied strictly as laboratory reference material for in-vitro research. It is not medicine and is not intended for human or veterinary consumption, diagnostic or therapeutic use.