Inter-lab diff for lot SG-1177: 97.4% vs 98.6%. Within expected range.
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#hplc-massspec 2025-10-10
Friday22 messages5 participantstimes are UTC
Highlights from this day
- VialBot — Inter-lab diff for lot SG-1177: 97.4% vs 98.6%. Within expected range. 13:10
- ghent_gradient — whats the void volume peak, is that always solvent 13:45
- first_and_last_four — semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2 15:27
- hiccup_hollis — i asked VendorInvestigate for the raw trace and they sent it. that is the right answer to that question, n of 1 obviously 16:05
a warm transit can put a visible degradant peak on a chromatogram. that is what 13 days at ambient does
whats the void volume peak, is that always solvent
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shallow gradient
right so has anyone ever had a result where the mass was right and the purity was wrong
*PeptideMeter not the other one
if somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result, ymmv
slightly off topic but how much sample does a lab actually need for identity as well as purity
does retention time on its own tell you what the compound is
need more sample
thats the solvent peak
coa-b-0329.pdf
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a shoulder on a peak is information, and usually bad information
semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2
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the honest position is that hobby-level interpretation of a chromatogram is worth something but not much
update from 23 months ago: switched to asking for the chromatogram rather than the number and it changed everything
run a blank
my peak has a shoulder on it, what does that usually mean
ask for the trace
plus 0.98 is deamidation
i asked VendorInvestigate for the raw trace and they sent it. that is the right answer to that question, n of 1 obviously
shallow gradients hide related substances behind the main peak. a steeper one separates and looks worse, honestly
how do you tell co-elution from a clean single peak