#hplc-massspec 2025-12-13

Saturday13 messages3 participantstimes are UTC

Highlights from this day

monoisotopic — if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic 14:24
monoisotopic — the honest position is that hobby-level interpretation of a chromatogram is worth something but not much 14:42
fridge_thermo — i asked VendorInvestigate for the raw trace and they sent it. that is the right answer to that question 15:11
snac_and_water — update on the earlier thing deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant 15:26
fridge_thermo — a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you, for what its worth 16:31

within inter-lab range

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if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic

monoisotopic and average diverge more the bigger the molecule. say which one you are quoting

the honest position is that hobby-level interpretation of a chromatogram is worth something but not much

show me the spectrum

i asked VendorInvestigate for the raw trace and they sent it. that is the right answer to that question

update on the earlier thing deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant

plus 0.98 is deamidation

need more sample

semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2

a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you, for what its worth

why do two labs integrate the same peak differently

the first peak is the solvent. it is always the solvent