does HPLC actually matter or is it forum lore at this point
does HPLC actually matter or is it forum lore at this point. I am not trying to be the "source?" guy. I would just like a source. System suitability — repeat injections, tailing factor, plate count, RSD on area — is what tells you the instrument was fit for the measurement that day. Without it, the purity figure is…
Method questions stay here; supplier claims go to c/vendorvetting with a document attached.
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.
How old is the column and roughly how many injections has it seen?
This. A shoulder that does not baseline-resolve is a question, not a quantity.
That is area percent, not mass percent. The trace cannot give you the second one.
Yes. Retention time is a hypothesis about identity. Mass is the answer.
Can you post the trace with the axes labelled?
I would not blame the sample yet. Everything you have described is consistent with the column rather than the vial.