This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Building on post #88 rather than restating 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".
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.
Reading it again, the caveat matters more than the finding.
Post #93 is the version of this I will quote in future. One addition.
Endotoxin testing is separate: a certificate of purity says nothing about endotoxin. A chemically pure preparation can carry a clinically significant endotoxin load. If endotoxin matters, it needs to be tested and reported.
It is worth checking rather than assuming, which costs nothing.
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.
This has been discussed before and I could not find the thread, so, again.
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 a small point and it changes the answer, which is an awkward combination.
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.
Useful. I had the fact and not the reason, which turns out to be the important half.
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".
Not disagreeing with anyone above, just adding the bit I keep having to look up.
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.
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.
Noting that the question and the thing people usually mean by it are different.
Post #102 is the version of this I will quote in future. One addition.
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".
I would treat that as a working assumption and revisit it.
Reading old certificates: if a certificate is dated years ago, the lot it describes might be old. That is not automatically a problem but it is worth noting. Fresh testing on the current lot is stronger than old testing on an older lot.
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 a conclusion. A place to stand while looking for one.
Post #104 describes the usual case. This is about the unusual one.
Asking for the batch record rather than the certificate is a reasonable request and the response to it is informative whichever way it goes.
If anyone has run this properly I would rather read that than my own guess.
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.
Post #106 answers the question as asked. The question underneath it is different.
"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.
I have kept the units in throughout, for the obvious reason.
I read post #108 twice before replying, because I had assumed the opposite.
Peptide content and chromatographic purity are separate determinations and a certificate that reports only one has answered only one question. Content is the one that tells you how much is in the vial.
The literature is thinner on this than the confidence in the thread implies.
On post #107 — agreed on the reasoning, with one qualification.
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.
Stating my assumptions rather than smuggling them in.
Picking up post #111: that is the part I would want checked first.
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".
One case, stated as one case.
Understood. Thank you for being specific about the limits of it.
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 right answer here may simply be that it has not been measured.
Worth separating two things that post #111 runs together.
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.
I would want the raw data before agreeing with my own summary of it.
Reading old certificates: if a certificate is dated years ago, the lot it describes might be old. That is not automatically a problem but it is worth noting. Fresh testing on the current lot is stronger than old testing on an older lot.
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.
I keep a log of this specifically because memory is unreliable about it.
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