From the other side of the consultation, briefly. It helps to ask what evidence would change your mind before you look at any. If nothing would, the discussion is not about evidence, and it is better to say so early than to spend nine posts discovering it.
Following on from Dr.MetabolicMD — and this may be the naive question:
Why two laboratories report different purity for the same batch, and which number to believe?
Sigma-Aldrich — Research-Grade Standards
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Shop Reference StandardsDebRD_ATL said:It helps to ask what evidence would change your mind before you look at any.
Agreeing with DebRD_ATL, and the qualification matters more than the agreement. One addition: an unstated method makes a report close to uninterpretable. "99% pure" without the technique, the standard and the conditions is a claim, not a measurement.