How to Read a Janoshik COA — HPLC, Mass Spec & the Numbers That Matter
A line-by-line walkthrough of a third-party certificate of analysis: what HPLC purity, net peptide content, and mass-spec identity actually prove.
Harrison Peralta · Updated Jun 22, 2026 · 9 min read
- A COA certifies three separate things — identity, purity, and how much actual peptide is in the vial. They are not the same number.
- “99% HPLC purity” and “99% net peptide content” answer different questions. A vial can be highly pure and still light on peptide by mass.
- A report is only as trustworthy as its chain of custody: a matching batch number, a recent test date, and a named, independently verifiable lab.
What a COA certifies
Every credible certificate of analysis answers three separate questions: what the compound is, how clean it is, and how much actual peptide you are paying for. Treat them as one number and you will overpay for the wrong thing.
The share of a vial’s total mass that is actual peptide, once water, salts, and synthesis counter-ions are subtracted. A vial can be 99% pure by HPLC and still only 80% peptide by mass — purity and content are not the same claim.
Verify these five fields on every report
- The batch number on the report matches the batch printed on your vial.
- The testing lab is named — and the report is verifiable on that lab’s own portal.
- The test date is recent, not recycled from an older batch.
- An HPLC chromatogram is included, showing a single dominant peak.
- A mass-spec result confirms the observed mass equals the expected mass.
Three numbers, three questions
| Test | What it answers | Good result |
|---|---|---|
| HPLC purity | How clean is the peptide fraction? | ≥ 99% main peak |
| Net peptide content | How much peptide by mass? | Stated & ≥ 80% |
| Mass spec | Is it the right molecule? | Observed = expected |
A COA certifies what a material is — not that it is safe for any use. Nothing here is medical, dosing, or human-use guidance. Products are evaluated for laboratory research only.
Bottom line
Read the header before the headline number. A recent, batch-matched report from a named, independently verifiable lab — showing high HPLC purity and a stated net peptide content — is worth far more than a bigger percentage you cannot trace to your vial.
