baseline resolved means the trace comes back down between the peaks. if it does not, the integration is a judgement call, check the axes first
Thread · #hplc-massspec · 2026-05-11
integration differences between two labs on the same trace
Spun off from a message in #hplc-massspec on 2026-05-11. 17 messages, 3 participants.
The message this came from
- HPLC_Hank — integration differences between two labs on the same trace are real and they are usually small, one sample, one lab. covers most of it 06:43
on the envelope thing anyone compared area percent against a proper quantitative assay on the same sample
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two labs a point or two apart on the same lot is normal and gets mistaken for one of them being wrong constantly, both labs can be right here
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for anyone reading their first trace a two point gap between labs is entirely explicable by a different gradient and a different column age, and the fragments ideally
plus 0.98 is deamidation
post the axes
ah missed this, thats the solvent peak
a broad late peak is usually something more hydrophobic than the target and it is usually small, ask for the raw trace
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the arithmetic is the useful skill here. you can check a mass difference yourself in about ten seconds, happy to be corrected on the mass
a shoulder is unresolved, not absent. a shallower gradient will usually pull it out
is uv at 214 or 280 better for peptides, or should i ask this elsewhere
if you post a trace, post the axes. a chromatogram without a time axis is a shape
looking at a spectrum now if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic, area percent, not mass percent
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on the envelope thing a shoulder on the main peak at this scale is usually a closely related species and it is worth asking about, system suitability would tell us if the run was valid
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baseline resolved means the trace comes back to baseline between the peaks. eyeballing it is fine for this channel
a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you
summary already judged