Reading rather than answering, but this is the post I would point somebody at.
0 likes 3mo
Analytics · COA interpretation · continued
Revisiting: A field-by-field walk through a certificate of analysis posts 31–42
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
r.jhannsdttir, post #2: The opening post answers the question as asked. The question underneath it is different. Field-by-field walk through a certificate came up in a thread eighteen months ago and was answered well. I cannot find it, which is itself the problem, so here is the reconstruction. Go to post
A certificate of analysis is a statement by its issuer that a defined test was performed on a defined lot and produced a defined result. That is all it is, and it is not nothing. What makes it usable: lot identifier matching the container, test date, method identification specific enough to reproduce, the actual result as a number, and the acceptance criterion stated separately from the result.
au.pereira, post #9: The bit of field-by-field walk through a certificate 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
I read post #30 twice before replying, because I had assumed the opposite.
Asking for the batch record rather than the certificate is a reasonable request and the response to it is informative whichever way it goes.
I would not lead a decision with this, but I would not ignore it either.
Taking post #32 at face value and following it one step further.
A certificate is a statement by its issuer that a defined test was performed on a defined lot and produced a defined result. That is all it is, and it is not nothing.
A guess, clearly labelled as one.
0 likes 3mo
When method identifiers are missing: "reversed-phase HPLC" is less specific than "reversed-phase HPLC at 214 nm on a C18 column with a 10 to 40% acetonitrile gradient over 20 minutes". The second lets someone reproduce the analysis. The first does not.
Happy to be corrected if someone holds better data than mine.
2 likes 3mo
Collapsed as off-topic by two members at trust level 3 or above
On field-by-field walk through a certificate, I would rather understate and be corrected upward than overstate and be quoted. That is a house style here and it is a good one.
s.ivaturi, post #32: Reading this field-by-field walk through a certificate thread as someone who came in with a fixed view: the third and seventh replies moved me and the confident ones did not. Go to post
What fields matter on a certificate: lot number matching the vial, test date, the analytical method stated specifically, the measured result as a number, and the acceptance limit stated separately. A certificate missing any of these is weaker.
OTeixeira, post #27: Answering the question post #25 raises rather than the one it answers. "Not less than 98 per cent" is a specification. "98.3 per cent" is a result. A certificate carrying only the first has not told you what was measured. Reading it again, the caveat matters more than the finding. Go to post
Adding a small correction to the field-by-field walk through a certificate summary above rather than a disagreement with it. The substance holds; one of the figures is out by a factor that matters.
That matches what I have seen, for whatever a single anecdote is worth.
4 likes 3mo
e.almeida, post #4: 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. Go to post
On post #39 — agreed on the reasoning, with one qualification.
I would keep field-by-field walk through a certificate 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.
s.demir, post #36: When method identifiers are missing: "reversed-phase HPLC" is less specific than "reversed-phase HPLC at 214 nm on a C18 column with a 10 to 40% acetonitrile gradient over 20 minutes". The second lets someone reproduce the analysis. The first does not. Happy to be corrected if someone holds better data than mine. Go to post
Picking up post #39: that is the part I would want checked first.
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.
This topic was referenced in
- Coming back to: "Greater than or equal to 99%" as a specification rather than a resultAnalytics › COA interpretation · 2 replies
- When a tidy document is a signal and when it is decoration — does this still hold?Analytics › COA interpretation · 7 replies
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