Reading a COA without getting lost: what do you actually check?

A Certificate of Analysis can look intimidating, but you don't need a chemistry degree to sanity-check one. The parts I've learned to look at: - Is it for THIS batch? A COA tied to a different lot number tells you about a different vial. - Identity vs. purity — mass spec answers "is this the right molecule?", HPLC answers "how much of it is the thing vs. impurities?" You want both, not just a purity % with no identity test. - Who ran it? "Third-party" means an independent lab, not the seller testing their own product — that independence is the entire point. - What's NOT shown — a clean COA doesn't test for sterility or endotoxins unless it says so. I'm not naming labs or vendors here — just literacy. What do you check first on a COA, and what's an instant red flag for you?