This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Nothing here should be read as an accusation against a named company, and the guidelines exist so that reports remain reports.
I would put this at better than even and not much better.
Inconsistency across documents: a certificate stating one purity, a website claiming another, and a supplier's verbal representation claiming a third, all on the same product, is a red flag for either incompetence or deception.
Old habit: I write down the expected answer before I calculate it.
On Identical chromatograms the community has more anecdote than the confidence in this thread implies, and I include my own contribution in that.
Adding the measurement that post #31 says would settle it.
Posting my Identical chromatograms numbers with the method attached so they can be discounted properly. Uncontrolled, unblinded, and collected by someone who wanted a particular answer.
Noted, and I have changed what I was going to do on the strength of it.
Prices well below the rest of the market are a fact rather than a finding. They are worth noting and they do not establish anything on their own.
On post #36 — agreed on the reasoning, with one qualification.
I would keep Identical chromatograms and the decision it usually gets used for separate in this thread. They are related and they are not the same question, and merging them is why the last one went badly.
Picking up post #36: that is the part I would want checked first.
Identical chromatograms is worth one more sentence than it usually gets, and the sentence is the one about how the number was arrived at.
Building on post #39 rather than restating it.
Trying to state the Identical chromatograms position in a way that someone who disagrees would recognise as fair, because I do not think the version in this thread passes that test.
Inability to trace lots: if you ask "where was this synthesised, by whom, under what conditions" and cannot get a clear answer, that is a red flag. Traceability is not glamorous but it is foundational.
The guidelines draw that line for a practical reason as much as a fair one: reports accumulate into something useful and allegations do not.
Correct me on the arithmetic if it is wrong; I would rather know.
Worth separating two things that post #42 runs together.
Keep the two claims separate. "The result on this lot did not match the certificate" is a report that can be checked. "This supplier is dishonest" is an allegation about intent and nothing in a chromatogram supports it.
The claim is narrower than it sounds, and deliberately so.
Identical chromatograms is a good example of a question where the honest answer is boring and the interesting answers are unsupported. I would go with boring.
Second this, and I would have said it less carefully.
The arithmetic in post #47 is right; the assumption feeding it is the part to check.
Identical chromatograms 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.
Answering the question post #46 raises rather than the one it answers.
The strongest single signal available cheaply is what happens when you ask a technical question. A quantitative answer inside a working day is difficult to fake at scale.
I have written this out at length because the short version keeps being misread.
A document with no method identification is not evidence of anything wrong. It is evidence that the document cannot be checked, which is a different and weaker statement.
Taking post #49 at face value and following it one step further.
The most useful contribution to this subcategory is a resolved case written up with the resolution, because the unresolved ones are all anyone remembers.
I would want a second opinion before relying on that.
I read the earlier replies on Identical chromatograms 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 honest answer on Identical chromatograms is that it depends, and the useful part is the list of what it depends on. Four items, in rough order of how much they matter.
Most people get the first two right and then argue about the fourth.
This is the first time the answer has come with its own limits attached. Appreciated.
This follows post #53 rather than contradicting it.
The guidelines draw that line for a practical reason as much as a fair one: reports accumulate into something useful and allegations do not.
Scoping that to what I have actually seen rather than what I have read.
On Identical chromatograms I would separate what is worth knowing from what is worth acting on. The first list is long and the second is short, and conflating them is how threads get heated.
Counterpoint on Identical chromatograms, offered without confidence: the same observation is consistent with a much duller explanation, and nobody has ruled the dull one out.
On post #57 — agreed on the reasoning, with one qualification.
A stock listing that never changes and a lead time that never varies are both worth noticing. Real operations have variation in them.
The short answer was in the first line; everything after is the working.
The arithmetic on Identical chromatograms is the easy part and it is where the errors are, which is an uncomfortable combination. Show your working and someone will catch it.