[Meta] proposal — a flair for water content posts
proposal — a flair for water content posts. Nothing about this affects the ranking maths, before anyone asks.
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 individually is a much stronger document than a single total, because it tells you the shape of the impurity profile rather than its size.
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.
I will update this if the picture changes rather than quietly leaving it up.
best — the order this archive was captured in
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.
What does the method line actually say? Not the technique — the column and the gradient.
I would not read a rounded figure as evasive. Plenty of documents round to one decimal as house style.
Net peptide content is the fraction of the powder that is actually peptide once counterion, water and residual solvent are accounted for. A 99% pure acetate salt can still be about 85% peptide by mass.
That is not what the method line says. It names the technique; it does not certify the operator.
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HPLC-UV and LC-MS answer different questions
net peptide content and purity are two different numbers on the same vial
Yes. The structure of the document matters at least as much as the number printed on it.
My first certificate had a compound name, a percentage and a logo. I thought that was normal. It is not, and now I know what to ask for.
Removed — cropped document. Post the whole page or do not post it; the fields people crop are the fields that matter.
Removed — cropped document.
Disagree on this specific point. Two honest labs can resolve that impurity differently and report different numbers.
the related substances line is where the story is
Sent one vial to PeptideMeter and Medutest. 99.1% and a claimed 99.0%. Cost me more than the vial and I would do it again.
identity and quantity are two questions and most documents answer one
post the whole document, not the headline number
Correction: that is net peptide content, not purity. Different number, different meaning, and the document says so if you read the row label.
Agreed on asking for the storage condition. It is one line and it changes how you read the entire stability claim.
- 1My first certificate had a compound name, a percentage and a logo. I thought…9 comments in this branch · started by u/sunday_shot_sal