is uv at 214 or 280 better for peptides
#hplc-massspec 2025-08-21
Thursday13 messages4 participantstimes are UTC
Highlights from this day
- spreadsheet_stu — a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you 08:58
- spreadsheet_stu — 214nm sees the amide backbone so it sees everything. 280 only sees aromatics 09:00
- border_force_bex — if the lab reports area percent without stating the wavelength, the number is less useful than it looks 09:04
- border_force_bex — do you trust an area percent from a shallow gradient if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic 09:33
- spreadsheet_stu — ok so oxidation is about plus 15.99 Da and is usually methionine or tryptophan semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2 10:18
ms/ms or it isnt identity
thats the solvent peak
a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you
214nm sees the amide backbone so it sees everything. 280 only sees aromatics
retention time is a hint
if the lab reports area percent without stating the wavelength, the number is less useful than it looks
why does integration change the number so much
do you trust an area percent from a shallow gradient
if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic
whats the void volume peak, is that always solvent
genuine question whats a normal gradient for a peptide this size
need more sample
ok so oxidation is about plus 15.99 Da and is usually methionine or tryptophan
semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2