How to Read a Peptide COA: A Field Guide for Researchers

A COA is one page that can contain three honest numbers or five elegant fictions. Here is how to tell which you’re holding — block by block.

The anatomy of a real certificate

Header — who, what, when. Compound name, CAS, batch/lot code, synthesis or purification date, report date. The batch code must match your vial label exactly; the dates must be chronologically possible. Decorative COAs fail here surprisingly often.

Identity — usually LC-MS or MALDI. Expect an “m/z found vs calculated” pair. For GHK-Cu the found mass should sit near the copper-free peptide’s calculated mass plus the metal adduct — if you can compute expected mass with the MW calculator, you can check their arithmetic in 30 seconds.

Purity — HPLC area%. Read the method: gradient, column class, detection wavelength (214 or 220 nm for peptide bonds). A bare “99%” with no method line is marketing. Peptides with Cys residues, salts, or acetate counter-ions legitimately report lower area% — ask which.

Water and residue content. Lyophilized powder is never 100% solid: 5–10% residual water and TFA/acetate salts are normal. Good COAs report them (Karl Fischer or qNMR notes); the number explains why vial “mass” and pure-peptide mass differ — the exact accounting trap covered in our reconstitution guide.

Sign-off. A lab name, location, and analyst reference that exist when you look them up.

The eight-point checklist

1. Batch code matches the vial in your hand
2. Found vs calculated mass, both printed
3. HPLC method line present (column/gradient/λ)
4. Purity consistent with the compound’s difficulty (no universal 99.9%)
5. Water/salt content disclosed
6. Dates chronologically sane
7. Issuing lab identifiable and findable
8. Numbers reproducible from your own MW math

Any two of these missing and the document is a sales sheet. Our quality process page states exactly what each Vyroval batch ships with — including what we don’t test for, which is the line most COA marketing quietly omits.

For laboratory research use only. Not medical advice.