if the lab reports area percent without stating the wavelength, the number is less useful than it looks
#hplc-massspec 2025-03-06
Thursday16 messages2 participantstimes are UTC
Highlights from this day
- point_two_five — a certificate with a number and no chromatogram is asking you to trust the integration you cannot see integration choices move the number by a few tenths easily. that… 12:41
- point_two_five — the first peak is the solvent. it is always the solvent 12:44
- gall_bladder_gav — how do you tell co-elution from a clean single peak 12:54
is uv at 214 or 280 better for peptides
a certificate with a number and no chromatogram is asking you to trust the integration you cannot see
integration choices move the number by a few tenths easily. that is most of your inter-lab variance
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the first peak is the solvent. it is always the solvent
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truncations show as a mass deficit matching one or more residues. you need the sequence to say which, for what its worth
does ms/ms actually prove identity or just make it very likely
a warm transit can put a visible degradant peak on a chromatogram. that is what 16 days at ambient does
co-elution is the failure mode that a beautiful single peak is most likely to be hiding
you need more sample for identity than for purity. plan for that when you post it, someone check my working
how do you tell co-elution from a clean single peak
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has anyone ever had a result where the mass was right and the purity was wrong
a shoulder on a peak is information, and usually bad information
i asked Janoshik for the raw trace and they sent it. that is the right answer to that question
while im here how would a truncation sequence show up
a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you
i was wrong about tailing factor. it is usually the injection or the pH, not the column