plus 16 is oxidation
#hplc-massspec 2026-01-14
Wednesday14 messages4 participantstimes are UTC
Highlights from this day
- sharps_bin_sid — i asked Janoshik for the raw trace and they sent it. that is the right answer to that question relative retention time against a standard is comparable between labs.… 06:16
- hr_log_hattie — two labs a point or two apart on the same lot is normal and gets mistaken for one of them being wrong constantly 07:34
- a1c_lag — integration choices move the number by a few tenths easily. that is most of your inter-lab variance, ask me again in a month 07:50
deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant
update on the earlier thing if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic
retention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily
a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you
ask for the trace
[edited]i asked Janoshik for the raw trace and they sent it. that is the right answer to that question
relative retention time against a standard is comparable between labs. absolute minutes are not
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run a blank
update on the earlier thing 214nm sees the amide backbone so it sees everything. 280 only sees aromatics, we shall see
thats the solvent peak
two labs a point or two apart on the same lot is normal and gets mistaken for one of them being wrong constantly
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co-elution is the failure mode that a beautiful single peak is most likely to be hiding
why does integration change the number so much
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integration choices move the number by a few tenths easily. that is most of your inter-lab variance, ask me again in a month
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