[Lab] ERP cagri — PeptideMeter came back 98.8% against a claimed 98.0%
Result first, context after: ERP cagri — PeptideMeter came back 98.8% against a claimed 98.0%. Everything below is how it was ordered, stored and sent.
Numbers, in the order they matter: 98.8% and 98.0%.
Chased a ghost peak for three weeks. It was the plumbing. It is always the plumbing.
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.
Screenshot none of this. Read the whole thread, including the parts where I am told I am wrong.
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nofollow and sponsored; nobody here is paid for it.best — the order this archive was captured in
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.
Left up. The integration disagreement in this thread is the most useful thing on the board this week.
Correction: that is a tailing factor, not a plate count. Different diagnostics for different problems.
Is that baseline drawn by the software or by hand?
Ran a blank after a high-concentration injection and found the carryover I had been calling an impurity.
the column has a history and it shows in the peak shape
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 — system suitability first. Without it the number is an assertion about the instrument, not the sample.
Reading a trace posted here, in the order I actually look at things.
Axes first — if the wavelength and the time axis are not labelled, I stop. Then the baseline: where has it been drawn, and does the drawing absorb anything. Then peak shape: fronting, tailing, a shoulder that never resolves. Then the blank, if one was run, for carryover.
Only after all of that do I look at the percentage, and by then I usually know how much weight it deserves. The number is the last thing on the page and the first thing everybody argues about, which is exactly backwards.
Cosigning the wavelength point. Half the disagreements in this board are two people looking at different detectors.