right so a certificate with a number and no chromatogram is asking you to trust the integration you cannot see
#hplc-massspec 2026-04-12
Sunday14 messages2 participantstimes are UTC
Highlights from this day
- monoisotopic — is there any point running a blank if the sample is the question 11:46
- monoisotopic — genuine question relative retention time against a standard is comparable between labs. absolute minutes are not 11:52
- monoisotopic — update on the earlier thing whats a plus one dalton shift usually 13:47
run a blank
does retention time on its own tell you what the compound is
is there any point running a blank if the sample is the question
M = 4113.6
[M+2H]2+ = (4113.6 + 2.02) / 2 = 2057.8
[M+3H]3+ = (4113.6 + 3.02) / 3 = 1372.2
observed 1372.3 -> consistent*VendorInvestigate not the other one
retention time is a hint
if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic, ill dig out the number
genuine question relative retention time against a standard is comparable between labs. absolute minutes are not
💀13
how much sample does a lab actually need for identity as well as purity
retention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily
👀1⚠️1📈1
update on the earlier thing whats a plus one dalton shift usually
integration difference
[edited]🔥2😂5🧊3
ms/ms sequencing is the only thing i would call identity. everything else is circumstantial
semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2
coming back to this is uv at 214 or 280 better for peptides
i was wrong about tailing factor. it is usually the injection or the pH, not the column