Annual ritual. HPLC tells you how much of the stuff is there (purity). It will not, on its own, tell you the stuff is the right molecule.
I maintain that for routine batch checking, a clean HPLC trace with a sane method is 90% of what most people actually need. Mass spec is the confirmation layer, not the everyday layer. I can already hear MassSpecMara sharpening a reply. Have at it.
Sharpened and ready. Harry, your "clean trace is 90%" only holds if you already know it's the right molecule. HPLC measures abundance, not identity. A perfect peak of an impostor is a perfect lie.
And mass spec without a purity read tells you the right molecule is present but not whether it's 99% or 70% of the vial. You confirm identity; I quantify reality. We are, infuriatingly, both necessary.
This is the correct conclusion, stated as a feud. For the record: HPLC = how much (purity, area percent); mass spec = is it the right molecule (identity). A complete COA carries both. Neither replaces the other.
Twenty replies of the two of you needing each other. Beautiful. Pinning this in my heart.
Reviving this to report a lovely clean trace today, during which I thought of Mara, who would point out it could still be the wrong molecule entirely. She lives in my head now, rent-free, holding a mass spectrum.
As I should. Identity first, abundance second, Harry forever in a distant and dignified second place. This is the natural order and I find it deeply peaceful.
You two are a whole trilogy at this point. Genuinely the clearest "purity vs identity" explainer on the internet is just the pair of you bickering across forty replies. Never resolve it.
Final word: we're both right. She's right about whether it's the right molecule, I'm right about how much of it is in there. Tetralogy continues. Smash subscribe.
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