A certificate of analysis (CoA) is the document that tells you what is actually in a vial of research peptide. A meaningful CoA is batch-specific — tied to the exact lot you received — not a generic marketing sheet. This guide explains each field, what "good" looks like, and the warning signs of a weak or generic CoA. For qualified researchers; all material is for in-vitro research use only.
The fields a CoA should contain
- Product name & batch/lot number — must match the label on your vial. If it doesn't, the document is meaningless for your material.
- Identity (mass spectrometry) — the observed molecular mass next to the theoretical mass from the sequence. A match confirms the correct molecule; this is the single most important check, and it is the one most often missing.
- Purity (HPLC) — a percentage (e.g. ≥99%) and the chromatogram. The number alone is easy to assert; the trace is the evidence.
- Net peptide content — the actual peptide fraction of the powder. Because synthetic peptides hold water and counter-ions, a "5 mg" vial rarely contains 5 mg of pure peptide. Determined by amino-acid or nitrogen analysis.
- Water content — typically Karl Fischer titration.
- Counter-ion — acetate or trifluoroacetate (TFA) salt content, quantified by ion chromatography/HPLC.
- Appearance & test date — e.g. white lyophilised powder; plus the date of analysis.
What "good" looks like
A strong CoA shows both identity and purity with their underlying data (the MS spectrum and the HPLC chromatogram), carries the same batch number as your vial, and reports net peptide content so you know the true quantity. For background on how those tests work, see our reference: research peptide purity & testing.
Warning signs of a weak or generic CoA
- No batch number, or one that doesn't match your vial — the document isn't about your material.
- Purity figure with no chromatogram — an unverifiable claim.
- No mass-spec identity — purity without identity tells you a sample is clean, not that it is the right compound.
- The same CoA reused for every order — a real CoA 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. All products referenced are supplied strictly as laboratory reference materials for in-vitro research. They are not medicines and are not intended for human or veterinary consumption, diagnostic or therapeutic use.