chromatogram is the most under-discussed thing on this board
chromatogram is the most under-discussed thing on this board. I have gone back and forth on this for months. 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 unanchored. Area…
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.
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Can you post the trace with the axes labelled?
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.
Yes — system suitability first. Without it the number is an assertion about the instrument, not the sample.
Can you post the trace with the axes labelled?
Adding one practical thing — run the blank. It answers this before anyone has to argue about it.
Retention time shifted 0.4 minutes and I assumed the worst. It was the column temperature.
Carryover from a previous high-concentration injection looks exactly like a small impurity. The blank injection is four minutes and it removes the ambiguity entirely.
How old is the column and roughly how many injections has it seen?
What did system suitability look like on that sequence?