I keep seeing vendors post Certificates of Analysis but I honestly don't know how to evaluate them. Some are full multi-page PDFs from a named lab, others are a single cropped image with a purity number and nothing else. As a member trying to be a careful reader, what fields should I be checking?
I'm not asking anyone what to buy or use — just trying to understand the document itself. What makes a COA credible versus decorative?
Good question, and one we wish more people asked. A COA worth trusting names the testing lab, gives a sample/batch identifier that matches what's on the vial label, states the method (HPLC for purity, and increasingly mass spec for identity confirmation), and shows the actual chromatogram or spectrum rather than just a headline percentage.
A cropped image with one number and no lab name, no batch ID, and no method is effectively unverifiable. We're happy to have members email the lab directly to confirm a report we've posted came from them — a legitimate vendor should welcome that, not resist it.
That's really helpful, thank you. The batch-ID-matching-the-vial part is the thing I'd never have thought to check. Appreciate you laying it out without turning it into a pitch.
One thing I'd add as a member: purity and identity are two different questions. A high HPLC purity number tells you the sample is mostly one compound, but it doesn't by itself prove that compound is the peptide claimed — that's what an identity method like mass spec is for. Worth asking for both. Evidence on a lot of these is limited to begin with, so document quality is one of the few things you can actually scrutinize.
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