Most peptide CoAs are a purity percentage on a letterhead. A few are real analytical documents. Work through the nine questions below with the CoA open — any supplier's, ours included — and you'll get a score out of ten for how much that document actually proves, plus a list of what to ask for.
Nothing is uploaded. No file leaves your browser — you answer questions about the document in front of you, and the scoring happens on this page.
Answer the questions on the left as you read down the document.
This scores the document, not the peptide. A thorough CoA from a dishonest supplier is still a piece of paper — this cannot verify that the numbers are true, and it cannot detect a fabricated chromatogram. What it does tell you is how much the supplier has actually committed to, and what is worth asking for.
HPLC purity is the area-percent of the peptide fraction — of the peptide-ish material in the vial, how much is the one you want. Peptide content is different: the mass-percent of the vial's contents that is peptide at all. The gap between them is water and counter-ion, usually TFA or acetate, left over from synthesis and lyophilisation.
A vial can honestly be labelled 99% pure and contain roughly 70% peptide by mass. Two suppliers quoting the same purity at the same price can be selling you materially different amounts of peptide. A CoA that states purity and stays quiet about content is not lying — it is just not telling you the part that determines what you actually got.
We're rolling Certificates of Analysis out across the catalogue rather than claiming they're already everywhere. Where one exists for a lot, ask and we'll send it — and run it through this same checker. A tool that grades other people's paperwork is only worth anything if it's pointed at your own too. More on our testing →