[Question] how do you actually verify method development
Asking properly rather than in a comment on somebody else’s thread: how do you actually verify method development.
The system suitability argument, since it comes up whenever somebody posts a number without one.
Before the sample result means anything, the instrument has to be shown to be fit that day: replicate injections with an acceptable RSD on area, a tailing factor inside limits, adequate plate count, and a resolution check between the pair you care about.
None of that is exotic and all of it is routine in a laboratory that reports for a living. Its absence does not mean a number is wrong; it means the number is unanchored, and unanchored numbers should not be quoted to two decimal places on this board.
Resolution between two peaks depends on retention, selectivity and efficiency. A shallower gradient buys retention and usually resolution, at the cost of peak width and run time.
Area percent is the integrated area of your peak over the total integrated area at one wavelength on one gradient. Change any of those and the number changes without the sample changing.
Happy to answer the boring questions. Those are usually the ones worth asking.
best — the order this archive was captured in
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.
Right. And a blank between injections settles the carryover argument before it starts.
Is that baseline drawn by the software or by hand?
What wavelength, and what was the gradient?
That is area percent, not mass percent. The trace cannot give you the second one.
Disagree. Inter-lab spread of a point or two on this assay is ordinary and calling it a discrepancy misleads people.