What actually makes a supplier trustworthy? A working checklist

Solid list. I'd promote "real chromatograms, not just a number" to the top — it's the single line that separates a supplier showing its working from one showing its logo. Everything else flows from that.

Add: packaging that matches the compound's cold-chain needs. A perfect COA means little if the vials arrived cooked. Red flag for me is a padded envelope where an insulated mailer belonged.

Genuinely useful checklist from the community — and a fair bar to be held to. Per-batch COA with matching batch number, chromatogram and method shown, mass-spec identity, cold-chain-appropriate packaging, unambiguous research-use-only labelling. That's the standard we aim to meet; hold us to it.

Folding it all in: chromatogram-first, identity not just purity, cold-chain matched to the compound, RUO labelling clear, responsive support. That's the consensus checklist — I'll write it up clean as a pinned-worthy reference.

Folding the recent additions in: chromatogram-first, identity not just purity, cold-chain matched to the compound (loggers on long routes are fair to ask for), clear RUO labelling, responsive support. This checklist is becoming the reference — thank you all.