[Discussion] can we stop arguing about gradient until somebody posts a number
can we stop arguing about gradient until somebody posts a number. I would rather ask a basic question now than get this wrong quietly for two months.
Chased a ghost peak for three weeks. It was the plumbing. It is always the plumbing.
Sent the same vial to Janoshik and Medutest. 98.2% against a claimed 97.5%. The difference was the gradient, not the material.
Ran a blank after a high-concentration injection and found the carryover I had been calling an impurity.
That is everything I have. The rest is opinion and I have tried to keep it out.
best — the order this archive was captured in
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.
system suitability before you believe any number on the run
Correction: that is a tailing factor, not a plate count. Different diagnostics for different problems.
system suitability before you believe any number on the run
Adding one practical thing — run the blank. It answers this before anyone has to argue about it.
Is that baseline drawn by the software or by hand?
What did system suitability look like on that sequence?