We’ve published individual pieces on COAs, lot tracking, insurance, pricing signals, and storage claims across a year of issues. Readers have asked for a single consolidated checklist, so here’s the condensed version we actually use when evaluating a seller.

Documentation Checks

A current COA whose lot number matches the vial in hand, from a named third-party lab (not an in-house test), ideally including the underlying method rather than just a final percentage — covered in detail in our mass spec explainer.

“None of this is new information if you’ve read us for a year. It’s the first time we’ve put it all in one place.”

— from this newsletter’s own reporting practices, consolidated for this piece

Operational Checks

A clear, working contact method; consistent storage and shipping claims that match the specific compound’s known stability profile; and transparency, if asked directly, about where manufacturing actually happens rather than a vague “USA-based” claim that only describes where the label was printed.

Behavioral Checks

How a seller responds to a direct, specific question about testing methodology or a reported problem is often more informative than any document — defensiveness or vague deflection in that conversation is a meaningfully different signal than a seller willing to engage with the specifics.