semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2
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#hplc-massspec 2025-10-29
Wednesday21 messages5 participantstimes are UTC
Highlights from this day
- half_life_hal — semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2 14:16
- half_life_hal — truncations show as a mass deficit matching one or more residues. you need the sequence to say which 14:37
- non_scale_win — has anyone ever had a result where the mass was right and the purity was wrong 16:24
whats a plus one dalton shift usually
truncations show as a mass deficit matching one or more residues. you need the sequence to say which
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integration difference
ask for the trace
a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you
need more sample
[edited]shallow gradients hide related substances behind the main peak. a steeper one separates and looks worse, honestly
within inter-lab range
a shoulder on a peak is information, and usually bad information, ymmv
how much sample does a lab actually need for identity as well as purity
a certificate with a number and no chromatogram is asking you to trust the integration you cannot see
run a blank
[edited]how would a truncation sequence show up
do the arithmetic
has anyone ever had a result where the mass was right and the purity was wrong
fridge-thermometer.png
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thats a charge state
[edited]plus 16 is oxidation
deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant
can you tell a dimer from the chromatogram alone
thats co-elution