you need more sample for identity than for purity. plan for that when you post it
#hplc-massspec 2026-02-09
Monday21 messages4 participantstimes are UTC
Highlights from this day
- HPLC_Hank — genuine question relative retention time against a standard is comparable between labs. absolute minutes are not, someone check my working 16:23
- HPLC_Hank — how would a truncation sequence show up 17:25
- HPLC_Hank — i have had a lot where the mass was exactly right and the purity was 96.8. wrong question, right answer, not advice obviously 17:26
- HPLC_Hank — does retention time on its own tell you what the compound is 17:28
if the lab reports area percent without stating the wavelength, the number is less useful than it looks
genuine question relative retention time against a standard is comparable between labs. absolute minutes are not, someone check my working
do you trust an area percent from a shallow gradient
whats a normal gradient for a peptide this size
how would a truncation sequence show up
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i have had a lot where the mass was exactly right and the purity was 96.8. wrong question, right answer, not advice obviously
*PeptideMeter not the other one
does retention time on its own tell you what the compound is
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oxidation is about plus 15.99 Da and is usually methionine or tryptophan, i could be wrong
run a blank
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thats a charge state
shallow gradient
how do you spot a deletion in a sequence from mass alone
[edited]ask for the trace
baseline is drifting badly, is that the column or the mobile phase
[edited]how do you tell co-elution from a clean single peak
shallow gradients hide related substances behind the main peak. a steeper one separates and looks worse, honestly
ms/ms sequencing is the only thing i would call identity. everything else is circumstantial
whats the void volume peak, is that always solvent
thats co-elution