a shoulder on a peak is information, and usually bad information
#hplc-massspec 2025-07-31
Thursday28 messages7 participantstimes are UTC
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- VialBot — Digest for the week of 2025-05-21 has been published. 17:35
- VialBot — On this day 4 years ago this channel logged 27 messages. 18:01
- VialBot — Verification log updated: SGN — evidence added, status unchanged. 18:04
- c18_column — why do two labs integrate the same peak differently 19:38
- c18_column — deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant 19:39
Digest for the week of 2025-05-21 has been published.
if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic
[edited]is monoisotopic or average mass the one on most certificates
retention time is a hint
you need more sample for identity than for purity. plan for that when you post it
monoisotopic and average diverge more the bigger the molecule. say which one you are quoting
On this day 4 years ago this channel logged 27 messages.
Verification log updated: SGN — evidence added, status unchanged.
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tirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5
has anyone ever had a result where the mass was right and the purity was wrong
Digest for the week of 2024-11-10 has been published.
plus 16 is oxidation
ms/ms or it isnt identity
a certificate with a number and no chromatogram is asking you to trust the integration you cannot see
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need more sample
is there any point running a blank if the sample is the question
why do two labs integrate the same peak differently
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deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant
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semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2
the honest position is that hobby-level interpretation of a chromatogram is worth something but not much
ok so my peak has a shoulder on it, what does that usually mean
show me the spectrum
while im here can you tell a dimer from the chromatogram alone
do the arithmetic
whats the void volume peak, is that always solvent
thats the solvent peak
the first peak is the solvent. it is always the solvent