Annotated peptester Certificate of Analysis for Retatrutide, with numbered callouts for identity, purity, quantity and how to verify the report.

Peptide COA guide: why testing matters

Independent testing helps you understand what was in the sample a lab received. A genuine Certificate of Analysis can confirm identity, measure purity and report quantity. Depending on the panel, it may also screen for heavy metals, endotoxins or sterility. Research-use notes only. This site is not medical advice, not a clinic, and not an offer to sell compounds for human use.

How to read the main fields

Compound / identity — does the report name the peptide you think you bought?
Batch or lot — can you match it to the vial or product page?
Date — is the report recent enough for the stock you are looking at?
Laboratory — is a lab named, and can you verify the report if a public lookup exists?
Purity / quantity — read the numbers next to the method (e.g. HPLC), not a homepage banner.

Batch evidence vs marketing purity

A COA speaks to the sample submitted for that batch or report — not to every future vial, and not to a slogan on a product card. “99% purity” without a matching file, named lab and date is marketing. Prefer shops that publish reports you can open before checkout.

What a COA cannot prove

That every vial in a later shipment matches the tested sample
Sterility, safety or medical suitability if those tests are not on the certificate
That the shop is a clinic, pharmacy or licensed medicine supplier
Anything beyond the methods and analytes listed on that report

Honest interpretation still makes testing worth doing: it creates accountability and helps spot mislabelled, underfilled or wrong-identity products.

Compare shops next

Put this into practice on the best peptide suppliers Australia guide, or follow the checklist in how to choose a peptide supplier. Profiles: Ultima Life, EPAU, Nuvion Health, Tetra Compounds. Coupons: discount codes.