[Discussion] the COA advice in here is 2 years out of date
the COA advice in here is 2 years out of date, and I am aware this is a minority view on this board.
2 years — those are the numbers, and they are the ones I am willing to defend.
The document I was worried about turned out to be a re-issue with a later creation date. Asked, got the original, entirely ordinary.
Water content 3.8%, acetate 6.2%, purity 99%, net peptide about 90% of label weight. All four numbers honest, and I had to read it twice.
Please do not ask me what dose you should be on. I genuinely do not know and neither does anyone else here.
best — the order this archive was captured in
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.
Area percent or net peptide content? They answer different questions.
Same view. SGN prints the column and the gradient, which means somebody could actually reproduce the run.
Sent one vial to Medutest and VendorInvestigate. 97.6% and a claimed 97.0%. Cost me more than the vial and I would do it again.
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.
Did you ask for the batch-specific document, or is this the catalogue one?
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.
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.
net peptide content and purity are two different numbers on the same vial
Right, and net peptide content is where the counterion and the water go. Both numbers can be honest and very different.
post the whole document, not the headline number
Small fix — 214nm, not 280nm. It matters here because the impurity you are asking about barely absorbs at the longer wavelength.