[Correction] you cannot report area% to two decimals off that baseline
Explainer, as requested in the last thread: you cannot report area% to two decimals off that baseline.
Retention time shifted 0.4 minutes and I assumed the worst. It was the column temperature.
Gave the same trace to two people I trust and got two integrations about a point apart. That was the most educational afternoon I have had here.
Sent the same vial to Janoshik and VendorInvestigate. 97.8% against a claimed 97.0%. The difference was the gradient, not the material.
Corrections welcome, especially the pedantic ones. Pedantry is how this board earns its reputation.
best — the order this archive was captured in
Mass spectrometry answers identity. UV purity answers relative quantity under the run conditions. A document with one and not the other is answering half the question, and the half it answers should be stated.
Correction: that is a tailing factor, not a plate count. Different diagnostics for different problems.
How old is the column and roughly how many injections has it seen?
214nm sees the peptide bond, 280nm sees the aromatics
What wavelength, and what was the gradient?
Right. And a blank between injections settles the carryover argument before it starts.
Retitled: the original claimed a comparison the post does not actually make.
a shoulder is not an impurity until you can resolve it
Retitled: the original claimed a comparison the post does not actually make.
This is the whole methodological point of the board in one line.
Yes. Retention time is a hypothesis about identity. Mass is the answer.
That is area percent, not mass percent. The trace cannot give you the second one.
reproducibility beats resolution if you only get one of them
a blank injection between samples costs four minutes and settles most arguments
Started reporting my own integrations with the baseline choice stated. Arguments in my threads dropped by about half.
two labs, two gradients, two honest answers
you cannot report to two decimals off that baseline
ghost peak, check the plumbing first, it is always the plumbing
- 1How old is the column and roughly how many injections has it seen?11 comments in this branch · started by u/amara_haddad