Identical chromatograms across two different lots posts 61–88
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Narrowing post #60, because the general version has more than one answer.
Where the same certificate image appears with different lot numbers, that is a documentation finding worth reporting with the images attached.
Post #62 and I disagree about the size of the effect, not about the direction.
Nothing here should be read as an accusation against a named company, and the guidelines exist so that reports remain reports.
I am reporting what happened, not recommending it.
A note on how identical chromatograms gets discussed rather than on identical chromatograms itself: the confident posts get the replies and the careful ones get ignored, and the careful ones have been right more often.
Collapsed as off-topic by two members at trust level 3 or above
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.
The guidelines draw that line for a practical reason as much as a fair one: reports accumulate into something useful and allegations do not.
Worth separating two things that post #66 runs together.
If you are new and reading this thread for the answer to identical chromatograms: the answer is conditional, the conditions are in the third reply, and the rest of the thread is worth skipping.
This follows post #66 rather than contradicting it.
Reporting something here requires the batch, the date, the method and the document, which is exactly what makes the reports worth reading two years later.
That matches what I was told, which is not the same as knowing it.
Second-hand on identical chromatograms, so weight it accordingly — someone whose method I trust told me this and I have not verified it myself.
Narrowing post #68, because the general version has more than one answer.
Pricing patterns: unusually low prices for what are otherwise consistent with market rates might indicate lower quality, stolen goods, or a scam. Unusually high prices without justification raise different flags.
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.
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.
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.
It is the kind of thing that is obvious once and never again.
What I can speak to on identical chromatograms is narrow, so I will keep it narrow rather than generalising from it. Beyond that boundary I do not know.
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 read post #79 twice before replying, because I had assumed the opposite.
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 step people skip is the one I have spelled out.
The most useful contribution to this subcategory is a resolved case written up with the resolution, because the unresolved ones are all anyone remembers.
Old habit: I write down the expected answer before I calculate it.
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.
That is the honest state of it as of this week.
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.
I would want to see it done twice before believing it once.
Everything in post #83 holds. The case it does not cover is the one I have.
I keep a log for identical chromatograms specifically because my memory of it turned out to be systematically wrong in one direction. Six weeks of notes cost nothing and settled it.
Narrowing post #87, because the general version has more than one answer.
Two things can be true about identical chromatograms at once: the mechanism is plausible and the evidence for the size of the effect is thin. Most of the argument here is people defending the first against attacks on the second.
This topic was referenced in
- Coming back to: When a red flag was a misunderstanding, and the retractionSourcing › Red flags · 10 replies
Suggested topics
| Topic | Participants | Replies | Views | Activity |
|---|---|---|---|---|
|
Second pass at: Identical chromatograms across two different lots
Posting this under the heading it deserves: Second pass at: Identical chromatograms across two different lots Everything below is what sits behind that. Something about Identical chromatograms does not…
|
+81 | 93 | 13k | 4mo |
|
A certificate whose chromatogram axes do not match its stated method — one year on
A certificate whose chromatogram axes do not match its stated method — one year on Writing it up because I had to work it out twice and would rather nobody else did. Posting a small dataset on certificate…
|
+103 | 111 | 8.1k | 2mo |
|
A supplier that answers analytical questions with restated claims
On the subject in the title: A supplier that answers analytical questions with restated claims Working notes rather than a conclusion. Reading back through what has been written here about supplier, three…
|
+107 | 118 | 45k | 12mo |
|
Batch numbers that do not match the vial label
Batch numbers that do not match the vial label — setting out what I have, and where I think it stops being reliable. Structured question about turnaround and what it signals. I have started recording how long…
|
+43 | 48 | 8.9k | 2d |
|
Coming back to: Pricing far outside the range, in either direction
Pricing far outside the range, in either direction Writing it up because I had to work it out twice and would rather nobody else did. Pricing far outside the range — I have the observation and I do not trust…
|
+22 | 26 | 325 | 2y |
Related topics — sharing the tags mislabelling, underdosing, documentation quality
| Topic | Participants | Replies | Views | Activity |
|---|---|---|---|---|
|
Documentation that appears only after payment
Documentation that appears only after payment Writing it up because I had to work it out twice and would rather nobody else did. Proposing that documentation deserves a maintained page rather than a recurring…
|
+113 | 124 | 13k | 7mo |
|
What a simple presence test is genuinely useful for
What a simple presence test is genuinely useful for — that is the question, and I have not found it answered plainly anywhere I have looked. Trying to work out what would count as evidence on simple presence…
|
2 | 58 | 1d | |
|
Lateral-flow and colorimetric approaches: the specificity problem
Lateral-flow and colorimetric approaches: the specificity problem — setting out what I have, and where I think it stops being reliable. Lateral-flow and colorimetric approaches, and specifically the version…
|
2 | 4k | 9mo | |
|
Follow-up: Why we hide unevidenced fraud accusations and log the hiding
The question in the title: Why we hide unevidenced fraud accusations and log the hiding I will give what I have already checked below so nobody repeats it. Filing a documentation observation rather than a…
|
+12 | 16 | 17k | 12mo |
|
Second pass at: What "verified" means on our vendor pages, stated narrowly
Second pass at: What "verified" means on our vendor pages, stated narrowly — setting out what I have, and where I think it stops being reliable. A question about how a record should be read rather than about…
|
+94 | 102 | 20k | 3mo |