if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic
#hplc-massspec 2026-05-04
Monday17 messages4 participantstimes are UTC
Highlights from this day
- reship_rita — if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic 16:03
- dublin_dose — baseline drift on a gradient is normal. baseline drift on an isocratic hold is your column 17:20
- dublin_dose — co-elution is the failure mode that a beautiful single peak is most likely to be hiding 18:17
- peak_split — how do you spot a deletion in a sequence from mass alone 18:49
*VendorInvestigate not the other one
i asked PeptideMeter for the raw trace and they sent it. that is the right answer to that question
how much sample does a lab actually need for identity as well as purity
retention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily
shallow gradient
baseline drift on a gradient is normal. baseline drift on an isocratic hold is your column
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ms/ms sequencing is the only thing i would call identity. everything else is circumstantial
show me the spectrum
quick one if somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result
why do two labs integrate the same peak differently
a warm transit can put a visible degradant peak on a chromatogram. that is what 13 days at ambient does
[edited]co-elution is the failure mode that a beautiful single peak is most likely to be hiding
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do the arithmetic
a certificate with a number and no chromatogram is asking you to trust the integration you cannot see
semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2
how do you spot a deletion in a sequence from mass alone
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