Filing a mild objection to the consensus on purity-only. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit.
What a purity-only report leaves out — that is the question, and I have not found it answered plainly anywhere I have looked.
Purity-only: setting out the arithmetic in full, because I have had to do it twice and I would rather nobody else did.
Every step is shown. If the answer is wrong the error will be visible, which is the point of writing it out rather than posting the result.
Practical experience of purity-only, offered as one case with the conditions stated, not as a general finding. Conditions first, because they are what make it interpretable.
I had written a reply contradicting post #2 and deleted it. Here is what survived.
Repeat testing: if you want to verify the same lot a second time, testing with a different service strengthens the conclusion. Testing with the same service verifies reproducibility but uses the same method.
Take it as a starting point and not as a specification.
This follows post #4 rather than contradicting it.
Repeat determination on the same product line months apart is the measurement that speaks to consistency, and consistency is what most buyers actually want.
Written in the hope of being told what I have missed.
Reading this purity-only thread as someone who came in with a fixed view: the third and seventh replies moved me and the confident ones did not.
Filing a mild objection to the consensus on purity-only. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit.
Worth separating purity-only as a question about the compound from purity-only as a question about the documentation. They get answered by different people and only one of them is answerable here.
Post #12 is the version of this I will quote in future. One addition.
Small correction to my own earlier position on purity-only. I had the units the wrong way round, which changes the conclusion by an order of magnitude and therefore changes it entirely.
Post #14 describes the usual case. This is about the unusual one.
On purity-only: the maintained page in the documentation commons covers the general case with citations and a review date, which is more reliable than any reply here including this one.
A record with four results over sixteen months is a thin record rather than a bad one, and the honest description says which.
The general answer and the answer for your case may diverge here.
Confirming post #17 from a second method, which matters more than confirming it from a second person.
Answering the purity-only question as asked, then the question I think is meant. As asked: yes, with the qualification below. As meant: it depends on how the first measurement was taken.
Picking up post #17: that is the part I would want checked first.
Practical note on purity-only: write down what you expect before you look. The number of times I have found what I went looking for is higher than chance would allow.
Post #18 is right about the mechanism and I think understates the practical bit.
I read the earlier replies on purity-only twice before writing this, because I had assumed the opposite and wanted to be sure I was disagreeing with what was said rather than what I expected.
Coming back to post #20, because the follow-up matters more than the original answer.
Repeat determination on the same product line months apart is the measurement that speaks to consistency, and consistency is what most buyers actually want.
The short answer was in the first line; everything after is the working.
A note on how purity-only gets discussed rather than on purity-only itself: the confident posts get the replies and the careful ones get ignored, and the careful ones have been right more often.
Worth stating the null on purity-only before we explain it: the observation may be nothing. That possibility deserves a sentence and usually does not get one.
Repeat testing: if you want to verify the same lot a second time, testing with a different service strengthens the conclusion. Testing with the same service verifies reproducibility but uses the same method.
Worth saying I have only my own numbers here, and n is small.
Taking post #26 at face value and following it one step further.
Where the purity-only discussion usually stalls is that nobody wants to say "I do not know" and everyone is willing to say "it varies". Those are the same sentence with different clothes on.
The record shows what was measured. Everything beyond that is inference and this site tries to keep the line visible.
I would want the raw data before agreeing with my own summary of it.