[Question] how do you actually verify LC-MS
Right, the integration question again, but with numbers this time.
I have 13 data points over 6 weeks. The pattern is consistent enough that I do not think it is chance, and boring enough that nobody is going to screenshot it, which is usually a good sign.
The thing I would flag for anyone new: the effect I am describing showed up at week 3, not week 52. People give up long before the interesting part.
Interested in whether this matches other people's logs or whether I am an outlier.
best — the order this archive was captured in
A shoulder on the main peak that 5 analysts integrated 6 different ways. Same trace, 98.4 spread.
area% and mass% are not the same and this whole post conflates them
Not convinced. The evidence does not support that reading.
No. This is the kind of confident post that gets copied into a screenshot and repeated for years. Where is the evidence.
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That is net peptide content, not purity. Different number, different meaning.
Strongly agree. Largest single impurity tells a different story than total purity.
chromatogram or it did not happen
Respectfully this is a sample of one presented as a finding.
Strongly agree. Largest single impurity tells a different story than total purity.
What was the column and what gradient?
related substances are where the story lives, not the main peak
Yeah, the chromatogram profile matters more than the headline number.
area% and mass% are not the same and this whole post conflates them
area% and mass% are not the same and this whole post conflates them
Disagree on that part. 98.7% and 98.9% on the same vial is normal.
Yeah, the chromatogram profile matters more than the headline number.
co-elution is real and purity is usually not enough to resolve it
integration decision on a shoulder changes your number by half a point on its own
No. This is the kind of confident post that gets copied into a screenshot and repeated for years. Where is the evidence.
The related substances profile is way more interesting than the main peak %. A 98% with 8 peaks is different from a 98% that is one 33% impurity.
integration decision on a shoulder changes your number by half a point on its own
Adding to this: integration is doing more work than the comment implies.
Did they post the raw trace or just the summary?
Small correction: the trial was 5 weeks, not 34. Does not change your point but people will quote it.
Not to be pedantic but chromatogram and method development are being used interchangeably and they are not interchangeable in real life.
Strongly agree. Largest single impurity tells a different story than total purity.
related substances are where the story lives, not the main peak
Yeah, the chromatogram profile matters more than the headline number.
Detection wavelength? purity and that changes at different wavelengths.
- 1area% and mass% are not the same and this whole post conflates them7 comments in this branch · started by u/freya_baptista
- 2Yeah, the chromatogram profile matters more than the headline number.6 comments in this branch · started by u/clara_danquah