how much of what we believe about related substances actually comes from certificate of analysis threads
how much of what we believe about related substances actually comes from certificate of analysis threads. Searched first, found three threads that contradict each other, hence the post. Asked for the storage condition behind the stability statement. Got it in a sentence. It is a two-line email and almost nobody sends…
Ask what the stability statement was written against — temperature, light, and whether it was the lyophilised powder or the reconstituted solution. Those are three different claims.
Sent one vial to Janoshik and Janoshik. 99.4% and a claimed 98.5%. Cost me more than the vial and I would do it again.
Asked HJ for the batch-specific certificate and had the full document — batch, date, method line naming the column — inside six hours. That is now my baseline for everybody.
post the whole document, not the headline number
LC-MS gives you identity; UV purity gives you a relative quantity. A document with the first and not the second, or the reverse, is answering half the question.
Not quite. Two labs with different gradients can resolve a close-eluting impurity differently and both be reporting honestly.
the counterion is part of the mass you paid for
HPLC-UV and LC-MS answer different questions