[Question] COA — what am I missing here
COA — what am I missing here. I am not trying to be the "source?" guy. I would just like a source.
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 identity; UV purity gives you a relative quantity. A document with the first and not the second, or the reverse, is answering half the question.
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.
I will update this if the picture changes rather than quietly leaving it up.
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.
Right, and net peptide content is where the counterion and the water go. Both numbers can be honest and very different.
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.
Yes — and the reason to ask for the whole page is that the interesting parts are the ones people crop out to fit a screenshot.
area% is not mass%, and the difference is the whole game
Your name and address edited out of the screenshot above. The batch details are untouched and should stay.
Asked HJ for the batch-specific certificate and had the full document — batch, date, method line naming the column — inside six hours. That is now my baseline for everybody.
Asked HJ for the batch-specific certificate and had the full document — batch, date, method line naming the column — inside six hours.
Disagree on this specific point. Two honest labs can resolve that impurity differently and report different numbers.
Cosigning. The batch identifier is load-bearing, and a certificate that cannot be tied to the vial in your hand is not about your vial.
Sent one vial to PeptideMeter and Medutest. 98.1% and a claimed 97.5%. Cost me more than the vial and I would do it again.
Are the related substances itemised or is it a single total?