how much of what we believe about HPLC actually comes from LC-MS threads
how much of what we believe about HPLC actually comes from LC-MS threads. Searched first, found three threads that contradict each other, hence the post. 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…
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.
you cannot report to two decimals off that baseline
That figure cannot be quoted to two decimals off that baseline. The precision is not in the data.
Retention time shifted 0.4 minutes and I assumed the worst. It was the column temperature.
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.
baseline choice is a decision, not a measurement
Disagree. Inter-lab spread of a point or two on this assay is ordinary and calling it a discrepancy misleads people.