sophie_paris said:Most of what circulates confidently in this community traces back to one summary of one study, and the qualifier was dropped somewhere in the third…
There is a second half to this that has not been said yet. The useful move here is to separate what is established from what is widely repeated. Those two sets overlap less than the confident tone of most write-ups suggests, and the second set is where nearly all the disagreement on this board comes from.
One concrete data point for the thread. If you are going to change something, change one thing and give it long enough to express itself. Four weeks is the usual minimum for anything pharmacological on this board, and two weeks of data has told you almost nothing.
A narrower follow-up, since the general answer is now clear:
Why two laboratories report different purity for the same batch, and which number to believe?
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Shop Reference Standardsdave_SLC said:If you are going to change something, change one thing and give it long enough to express itself.
I read this differently from dave_SLC, on substance rather than tone. Filing an objection on the n=1 problem. Personal experience is genuine evidence about one person and very weak evidence about anybody else, and this thread keeps promoting the first into the second.
dave_SLC said:If you are going to change something, change one thing and give it long enough to express itself.
Agreed, and mass spec answers a question purity does not: identity. High purity tells you one thing dominates the chromatogram, not that it is the molecule you ordered. A mass within about a dalton of expected is the identity check.