[Question] batch — what am I missing here
batch — what am I missing here. If this has been answered properly somewhere, link me and I will delete. Ask what the stability statement was written against — temperature, light, and whether it was the lyophilised powder or the reconstituted solution. Those are three different claims. Related substances itemised…
The PDF creation date being later than the analysis date is usually a re-issue or a re-export. It is worth one question and it is not evidence of anything on its own.
Why the same vial can honestly produce three different numbers.
Purity by area percent is relative to what the detector saw on one gradient at one wavelength. Net peptide content subtracts counterion, water and residual solvent. Mass of peptide per vial is net content times fill weight, and fill weight has its own tolerance.
So a document reading 99% purity, 6% acetate and 4% water is describing a vial that is about 90% peptide by mass, and every one of those numbers is honest. The mistake is treating the headline figure as the answer to "how much peptide did I get".
Agreed — the itemised related substances table is the difference between a document and a receipt.
Correcting myself upthread: I said the date was missing and it is on the second page, which I had not scrolled to.
Correction: that is net peptide content, not purity. Different number, different meaning, and the document says so if you read the row label.
That is the catalogue certificate rather than the batch-specific one. Same layout, completely different status.
Is water content on the document? It changes your concentration arithmetic.
the lot on the vial has to match the lot on the page
the counterion is part of the mass you paid for
HPLC-UV and LC-MS answer different questions
the related substances line is where the story is
Agreed on asking for the storage condition. It is one line and it changes how you read the entire stability claim.