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.
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.
Bookmarking this. I will come back when I have something worth adding.
Confirming post #121 from a second method, which matters more than confirming it from a second person.
Residual solvent screening is not standard on these documents and its presence is a signal about the manufacturer's own systems rather than about the vial.
That is where I would start, not where I would stop.
"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.
Happy to be the one who is wrong here if it settles the question.
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.
On post #124 — agreed on the reasoning, with one qualification.
A document that puts the specification in the result column has told you the release criterion rather than the measurement. Those are different claims and the difference is the whole point of reading the document.
This is the version I would want a new member to read first.
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.
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".
Narrowing post #126, because the general version has more than one answer.
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 treat the number as indicative rather than as a measurement.
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 rule of thumb is fine; the edge cases are where it earns its keep.
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.
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".
Reading it again, the caveat matters more than the finding.
Coming back to post #131, because the follow-up matters more than the original answer.
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.
It is a small point and it changes the answer, which is an awkward combination.
Post #131 is right about the mechanism and I think understates the practical bit.
A document that puts the specification in the result column has told you the release criterion rather than the measurement. Those are different claims and the difference is the whole point of reading the document.
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.
It is worth stating the boring hypothesis before the interesting one.
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.
Somebody will have a better source than mine, and I hope they post it.
I read post #135 twice before replying, because I had assumed the opposite.
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".
Post #135 describes the usual case. This is about the unusual one.
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.
Worth checking against a second source before it gets quoted onward.
Adding the measurement that post #139 says would settle it.
The fields that make one usable: lot identifier matching the container, test date, method identification specific enough to reproduce, the result as a number, and the acceptance criterion stated separately from the result.
Where I would look next, rather than where I would stop.
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".
Noting that the question and the thing people usually mean by it are different.
Worth separating two things that post #143 runs together.
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.
When a document puts the specification in the result column, it has told you the release criterion, not the measurement. Those are different claims and the second is weaker.
Worth saying I have only my own numbers here, and n is small.
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 be interested in a counterexample if anyone has one.
| Topic | Participants | Replies | Views | Activity |
|---|---|---|---|---|
|
Counter-ion form: the field almost nobody reports — one year on
On the subject in the title: Counter-ion form: the field almost nobody reports — one year on Working notes rather than a conclusion. The question about Counter-ion form that I actually want answered is the…
|
+121 | 139 | 31k | 16mo |
|
Specification in the result column: why that is a meaningful error
Posting this under the heading it deserves: Specification in the result column: why that is a meaningful error Everything below is what sits behind that. A documentation question rather than an analytical…
|
+107 | 129 | 41k | 5mo |
|
Coming back to: "Greater than or equal to 99%" as a specification rather than a result
Posting this under the heading it deserves: "Greater than or equal to 99%" as a specification rather than a result Everything below is what sits behind that. Two reports on the same lot, and I would like help…
|
2 | 31k | 6mo | |
|
Counter-ion form: the field almost nobody reports
Counter-ion form: the field almost nobody reports Writing it up because I had to work it out twice and would rather nobody else did. Counter-ion form, from the point of view of someone who has read the…
|
3 | 11k | 2mo | |
|
Reconciling a label claim with a content assay
On the subject in the title: Reconciling a label claim with a content assay Working notes rather than a conclusion. The question about reconciling a label claim that I actually want answered is the second one…
|
+2 | 6 | 183 | 4mo |
| Topic | Participants | Replies | Views | Activity |
|---|---|---|---|---|
|
Revisiting: The report format the maintainers ask for, and why each field is there
Posting this under the heading it deserves: Revisiting: The report format the maintainers ask for, and why each field is there Everything below is what sits behind that. Structured report rather than an…
|
+100 | 108 | 57k | 1d |
|
Coming back to: Purity assay versus content assay: two different numbers
Purity assay versus content assay: two different numbers — setting out what I have, and where I think it stops being reliable. Asking about Purity assay versus content assay directly, because I have read four…
|
+71 | 77 | 31k | 23mo |
|
Follow-up: Reporting a discrepancy without making an allegation
Reporting a discrepancy without making an allegation Writing it up because I had to work it out twice and would rather nobody else did. A follow-up question about Reporting a discrepancy that I did not know…
|
2 | 24k | 19mo | |
|
Reflectance and photometric devices: precision in practice
On the subject in the title: Reflectance and photometric devices: precision in practice Working notes rather than a conclusion. I was wrong about reflectance and photometric devices in a thread last spring…
|
2 | 2.2k | 10mo | |
|
Cost versus information: making the trade-off explicitly
Cost versus information: making the trade-off explicitly Writing it up because I had to work it out twice and would rather nobody else did. Asking about cost versus information directly, because I have read…
|
+2 | 6 | 12k | 11h |