I read the earlier replies on Reused chromatograms across lots 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.
Reused chromatograms across lots: how to spot it — what changed since — setting out what I have, and where I think it stops being reliable.
What changes if the standard account of Reused chromatograms across lots is wrong? I ask because I have been treating it as settled and I noticed this week that I could not say why.
Working through the consequences rather than the evidence, since others here are better placed on the evidence.
I read the earlier replies on Reused chromatograms across lots 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.
The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".
That is a description of practice, not a recommendation of it.
Reporting rather than recommending, on Reused chromatograms across lots. What happened is above. Whether it should have is a different question and not one I am qualified to answer.
Bookmarking this. I will come back when I have something worth adding.
An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.
If it helps: the failure mode here is usually boring rather than dramatic.
Building on post #9 rather than restating it.
Reused chromatograms across lots has been discussed here with more heat than it deserves, mostly because two definitions have been in play the whole time.
The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".
Old habit: I write down the expected answer before I calculate it.
I came in to disagree and I am leaving without a disagreement.
Taking post #12 at face value and following it one step further.
Two claims get bundled together under Reused chromatograms across lots and they need separating. The descriptive one — this is what was observed — is usually well supported. The causal one — this is why — usually is not.
Almost every disagreement in threads like this one dissolves once you say which of the two you are making.
Post #14 and I disagree about the size of the effect, not about the direction.
A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.
I would rather this thread reach "we do not know" about Reused chromatograms across lots than reach a confident answer that nobody can support when asked.
On Reused chromatograms across lots, the part that usually goes wrong is that the question is asked as though it has one answer. It has a range, and the width of the range is the interesting bit.
If you can post the two or three numbers you are working from, several people here will check the arithmetic rather than argue about the conclusion.
Worth separating two things that post #18 runs together.
A request rather than an answer: could whoever has the primary source for Reused chromatograms across lots post it? I have seen the claim three times this month and each version had lost a qualifier.
Noted, and I have changed what I was going to do on the strength of it.
Confirming post #19 from a second method, which matters more than confirming it from a second person.
The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".
Adding a null result on Reused chromatograms across lots. I looked, carefully, and found nothing, and null results deserve posting precisely because they never are.
Reused chromatograms across lots would be much easier to settle if anyone reported the denominator. Almost nobody reports the denominator.
A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.
That is the honest state of it as of this week.
The strongest argument against my own position on Reused chromatograms across lots, stated as well as I can state it, since nobody else has yet.
Post #23 describes the usual case. This is about the unusual one.
Distinguishing three things in the Reused chromatograms across lots discussion that keep getting used interchangeably: the observation, the proposed mechanism, and the recommendation that gets attached to both.
An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.
I checked the source rather than the summary, and they differ.
Reused chromatograms across lots sits at the boundary between what this community can usefully discuss and what it cannot, and I think it falls on the discussable side, narrowly.