Analytics · COA interpretation · continued

Reused chromatograms across lots: how to spot it — what changed since posts 31–40

Analytics › COA interpretation batch & lot numbers amino acid analysis reference standards documentation quality Solved

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.

n.marsdenTL1Member14 Apr 2026#31

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".

0 likes 3mo

a.vestergaardTL218 Apr 2026 · edited#32

lyophil_margin, post #12: 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. Go to post

Marking my uncertainty on Reused chromatograms across lots explicitly. I am confident about the direction, much less confident about the size, and not confident at all that it generalises past the case in the first post.

4 likes in reply to #12 3mo

glossary_deskTL3Regular22 Apr 2026#33

Narrowing post #30, because the general version has more than one answer.

If someone has run Reused chromatograms across lots properly I would rather read that than my own reconstruction of it. Posting mine only because the thread has gone quiet.

18 likes 3mo

l.krastevTL226 Apr 2026#34

Following, with nothing to contribute beyond having asked the same thing elsewhere.

0 likes 3mo

fr.translation_moTL2Translator · FR30 Apr 2026#35

Post #33 is the version of this I will quote in future. One addition.

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.

1 like 3mo

e.nilsenTL24 May 2026#36

a.cabrera, post #10: Picking up post #7: that is the part I would want checked first. The bit of Reused chromatograms across lots that nobody enjoys is that the answer changes depending on what you are trying to decide with it. Say what the decision is and the thread will converge. Go to post

Reading back through the Reused chromatograms across lots threads from last year, the same three questions come up every time and only one of them has ever been answered properly. That seems like a documentation gap rather than a knowledge gap.

7 likes in reply to #10 3mo

aliquot_lineTL3Regular8 May 2026#37

e.tamm, post #19: 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. Not the answer, but possibly the question that gets there. Go to post

Reused chromatograms across lots is well covered in the tag pages, and the older discussions are better than the recent ones because they were argued out properly. Worth twenty minutes before adding to this one.

25 likes in reply to #19 3mo

v.stanescuTL212 May 2026#38

Answering the question post #36 raises rather than the one it answers.

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.

The mechanism is plausible, which is not the same as established.

0 likes 3mo

l.ibarraTL2Regular16 May 2026#39

On Reused chromatograms across lots: 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.

0 likes 2mo

a.delgadoTL220 May 2026#40

I had written a reply contradicting post #36 and deleted it. Here is what survived.

Answering the Reused chromatograms across lots 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.

0 likes 2mo

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