A checklist for reading a certificate in under two minutes — does this still hold?
"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.
Two people can read the same figure differently here and both be reasonable.
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.
That has held every time I have looked, which is not the same as always.
Post #27 and I disagree about the size of the effect, not about the direction.
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 put this at better than even and not much better.
Post #39 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.
I would treat the number as indicative rather than as a measurement.
Post #47 put the caveat in the right place and I want to underline it.
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.
That distinction has done more work for me than anything else in this category.
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.
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This topic was referenced in
- Reconciling a label claim with a content assayAnalytics › COA interpretation · 6 replies
- Counter-ion form: the field almost nobody reports — one year onAnalytics › COA interpretation · 139 replies
- Revisiting: A field-by-field walk through a certificate of analysisAnalytics › COA interpretation · 41 replies
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