peak at 4.2 min, nobody can tell me what it is, ideas
peak at 4.2 min, nobody can tell me what it is, ideas. Not a hot take, just something I have not seen said plainly here. Chased a ghost peak for three weeks. It was the plumbing. It is always the plumbing. A shoulder that does not baseline-resolve cannot be quantified honestly. You can report it as an unresolved…
Trace posted without axis labels — asked for a relabelled version rather than removing it.
Do you have the mass, or only the UV trace?
That figure cannot be quoted to two decimals off that baseline. The precision is not in the data.
What did system suitability look like on that sequence?
a blank injection between samples costs four minutes and settles most arguments
I would not blame the sample yet. Everything you have described is consistent with the column rather than the vial.
you cannot report to two decimals off that baseline
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.