[Discussion] certificate of analysis is doing more work than we give it credit for
certificate of analysis is doing more work than we give it credit for. Change my mind, genuinely — I have no stake in being right about this. How to ask for a batch record without it turning into a negotiation. One email, three requests: the batch-specific certificate for lot X, the method line behind it, and the…
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.
Related substances itemised individually is a much stronger document than a single total, because it tells you the shape of the impurity profile rathe
Adding the bit that always gets missed: the lot on the vial has to match the lot on the page, or none of this applies to your material.
Does the lot on the vial match the lot on the page?
Area percent is the peak area of your compound over the total integrated area, at one wavelength, on one gradient. It is a relative measure of what the detector saw, not a mass fraction of the vial.
Related substances itemised individually is a much stronger document than a single total, because it tells you the shape of the impurity profile rathe
Agreed, and the practical version is: ask for the itemised table. If it exists, you get it.
net peptide content and purity are two different numbers on the same vial
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.
area% is not mass%, and the difference is the whole game
area% is not mass%, and the difference is the whole game
Disagree on this specific point. Two honest labs can resolve that impurity differently and report different numbers.