[PSA] HPLC is not what most of this community thinks it is
HPLC is not what most of this community thinks it is. It comes up every few weeks and the answer has not changed. A shoulder that does not baseline-resolve cannot be quantified honestly. You can report it as an unresolved shoulder, which is useful information, or you can develop the method until it resolves. Chased a…
UV response is not uniform across species. At 214nm you are looking at the peptide bond, which is why it is the working wavelength for this class; at 280nm you only see tryptophan, tyrosine and phenylalanine.
area percent is relative to what the detector saw and nothing else
Yes — system suitability first. Without it the number is an assertion about the instrument, not the sample.
Mass spectrometry answers identity. UV purity answers relative quantity under the run conditions. A document with one and not the other is answering half the question, and the half it answers should be stated.
Mass spectrometry answers identity.
This is the whole methodological point of the board in one line.