need more sample
#hplc-massspec 2025-06-11
Wednesday22 messages6 participantstimes are UTC
Highlights from this day
- acetate_ash — unrelated but integration choices move the number by a few tenths easily. that is most of your inter-lab variance 20:27
- c18_column — why do two labs integrate the same peak differently 20:28
- VialBot — Reminder for acetate_ash: dose day is today. Set 9 days ago. 20:44
- acetate_ash — follow up how would a truncation sequence show up a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you 21:48
- VialBot — Reminder for acetate_ash: dose day is today. Set 9 days ago. 22:07
how do you tell co-elution from a clean single peak
integration difference
retention time is a hint
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a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you, ymmv
plus sixteen, is that always oxidation
shallow gradient
unrelated but integration choices move the number by a few tenths easily. that is most of your inter-lab variance
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why do two labs integrate the same peak differently
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Reminder for acetate_ash: dose day is today. Set 9 days ago.
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ms/ms or it isnt identity
thats a charge state
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how do you spot a deletion in a sequence from mass alone
semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2
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i have a number at about a third of what i expected, is that a charge state
right so co-elution is the failure mode that a beautiful single peak is most likely to be hiding, anyway
follow up how would a truncation sequence show up
a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you
monoisotopic and average diverge more the bigger the molecule. say which one you are quoting
you need more sample for identity than for purity. plan for that when you post it
i have had a lot where the mass was exactly right and the purity was 96.8. wrong question, right answer
Reminder for acetate_ash: dose day is today. Set 9 days ago.
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my peak has a shoulder on it, what does that usually mean