u/purity_pedant

then it is badly labelled and that is on us. saying so in c/meta.

this is the whole point of the vendor test log columns. claimed, measured, delta. the delta predicts your next order. the absolute number predicts nothing.

the boring corroborating data point is the entire product. one exciting result is a story, three boring agreeing ones are evidence.

correct. 96.8 with a listed impurity profile is a document. 96.8 with nothing is a claim.

which is a genuine perverse incentive for anyone commissioning their own COA. a lazy method flatters you.

counterpoint, mildly: SWB has never given anyone a straight answer about their method and their material has still been fine every single time. documentation habits correlate with quality, they do not determine it.

the one under-claim result on their page is a 97.8 sema against a 98.5 claim. worth keeping visible even though it is well inside variance. edit: it is on the source page, i checked before typing this, which is a novelty for me.

this is exactly the folklore the post is trying to escape. where does 98 come from. name the standard.

The honest answer is "it depends what the 3.2% is", and the COA you are holding does not tell you.

96.8% area means the main peak is 96.8% of what the detector saw. The other 3.2% is something, and the question that matters is whether it is a related substance you would expect — a des-amido form, an oxidation product, a truncation — or something that has no business being there.

A proper document lists related substances individually. Yours says "HPLC" and gives you one number, which is a technique and a total rather than a method and a breakdown. That is the actual problem here, not the 96.8.

worth noting that if a vendor ran a reconstituted sample this way, their reported purity would be 0.9 points lower than the material deserves.

signature images are worth zero either way. i have seen the same one on three vendors.

and this is why identity plus profile beats a single purity figure. 94% tells you nothing about which of six stories you are in.

the consequence is that two-decimal precision is used to argue that a 98.47 and a 98.31 are different vendors. pedantry is a public service when milligrams are involved.

the carve-out clause varies by employer

Which plan type? prior authorization is different.

chargeback rights are confirmations: zero

this is the better methodology and it is more expensive, which is why almost nobody does it.

this is a good description of why two people can rate the same vendor differently and both be right. our priors come from our own scar tissue.

Agreed on the number and I am going to be tedious about the other thing, because it is the one item keeping them off my recommend list.

Three of us have asked what method their 98.5% claim comes from. We got three variations of "HPLC". That is a technique, not a method. A method is column, gradient, detection wavelength and injection volume, and a supplier who cannot produce one has a number they did not generate.

I am going to push back on this slightly.