[Question] is 96.8% actually fine or am I being sold a rounding error
is 96.8% actually fine or am I being sold a rounding error, and before anyone asks: same batch throughout, single submission, no cherry-picking between services.
96.8% — those are the numbers, and they are the ones I am willing to defend.
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.
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.
If two or three other people have done the same thing we might actually learn something. Alone it is an anecdote.
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.
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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.
Agreed, and it is why QSC printing the column and gradient on the certificate is genuinely useful rather than decorative.
Disagree. Inter-lab spread of a point or two on this assay is ordinary and calling it a discrepancy misleads people.
What did system suitability look like on that sequence?
What did system suitability look like on that sequence?
This is the whole methodological point of the board in one line.
retention time alone is not identity
Right. And a blank between injections settles the carryover argument before it starts.
That is area percent, not mass percent. The trace cannot give you the second one.
a blank injection between samples costs four minutes and settles most arguments
KP sent me the column, the gradient and the theoretical mass without being asked. That is a short list and they are on it.
- 1Disagree. Inter-lab spread of a point or two on this assay is ordinary and…7 comments in this branch · started by u/crosspost_bot_no