reading certificate of analysis threads from 2024 and half of it aged badly
reading certificate of analysis threads from 2024 and half of it aged badly, and I am aware this is a minority view on this board. UV at 214nm sees the peptide bond and picks up almost everything; at 280nm you are looking at aromatics only. Which wavelength the number came from is part of the number. LC-MS gives you…
Removed — cropped document. Post the whole page or do not post it; the fields people crop are the fields that matter.
Removed — cropped document.
This is the sentence to take away. The rest of the thread is footnotes to it.
Careful — "the metadata looks odd" is a reason to ask a question, not a conclusion. Re-issues are ordinary.
Careful — "the metadata looks odd" is a reason to ask a question, not a conclusion.
Agreed, and the practical version is: ask for the itemised table. If it exists, you get it.
Batch number and date of analysis, are both on there?
the lot on the vial has to match the lot on the page
Did you get the chromatogram or only the summary line?
I would not read a rounded figure as evasive. Plenty of documents round to one decimal as house style.
a certificate with no method line is decorative
That is the catalogue certificate rather than the batch-specific one. Same layout, completely different status.
a total of 0.4% tells you less than four named impurities adding to 0.6%
Pushing back a little: a missing field is usually presentation, not concealment. Ask for the full document before drawing conclusions.
the related substances line is where the story is
post the whole document, not the headline number
post the whole document, not the headline number
amylin_amy has the distinction right — one is a fraction of the detector signal, the other is a fraction of the mass.