is a tailing factor of anything specific a problem
#hplc-massspec 2025-03-30
Sunday24 messages9 participantstimes are UTC
Highlights from this day
- VialBot — Reminder set. I will post here in 6 days. 20:16
- blank_run — update from 21 months ago: switched to asking for the chromatogram rather than the number and it changed everything 21:10
- HPLC_Hank — baseline is drifting badly, is that the column or the mobile phase 21:45
- HPLC_Hank — whats a plus one dalton shift usually if the lab reports area percent without stating the wavelength, the number is less useful than it looks 21:48
genuine question i have had a lot where the mass was exactly right and the purity was 96.8. wrong question, right answer
Reminder set. I will post here in 6 days.
i was wrong about tailing factor. it is usually the injection or the pH, not the column
*VendorInvestigate not the other one
is monoisotopic or average mass the one on most certificates
a certificate with a number and no chromatogram is asking you to trust the integration you cannot see
thats co-elution
deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant
shallow gradients hide related substances behind the main peak. a steeper one separates and looks worse, honestly
a warm transit can put a visible degradant peak on a chromatogram. that is what 19 days at ambient does
update from 21 months ago: switched to asking for the chromatogram rather than the number and it changed everything
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update on the earlier thing the first peak is the solvent. it is always the solvent
[edited]plus 0.98 is deamidation
ms/ms sequencing is the only thing i would call identity. everything else is circumstantial
shallow gradient
baseline is drifting badly, is that the column or the mobile phase
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whats a plus one dalton shift usually
if the lab reports area percent without stating the wavelength, the number is less useful than it looks
ms/ms or it isnt identity
within inter-lab range
need more sample
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genuine question semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2
do the arithmetic
sorry to jump in if somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result