why does integration change the number so much
#hplc-massspec 2026-01-12
Monday25 messages6 participantstimes are UTC
Highlights from this day
- eight_mm — why do two labs integrate the same peak differently 19:04
- VialBot — Digest for the week of 2025-03-10 has been published. 20:01
- LC_MS_Lena — a warm transit can put a visible degradant peak on a chromatogram. that is what 5 days at ambient does 20:20
- VialBot — Digest for the week of 2025-11-07 has been published. 20:24
why do two labs integrate the same peak differently
🤝10
thats the solvent peak
a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you
how would a truncation sequence show up
show me the spectrum
a shoulder on a peak is information, and usually bad information
is monoisotopic or average mass the one on most certificates
thats a charge state
📉11
coming back after 14 months, what changed in how you read these
within inter-lab range
Digest for the week of 2025-03-10 has been published.
⚠️7📉16
run a blank
🤝6📈4👀1
is uv at 214 or 280 better for peptides
[edited]if the lab reports area percent without stating the wavelength, the number is less useful than it looks
right so co-elution is the failure mode that a beautiful single peak is most likely to be hiding
a warm transit can put a visible degradant peak on a chromatogram. that is what 5 days at ambient does
📈16👀13✅3
nobody runs enough blanks, including me
[edited]Digest for the week of 2025-11-07 has been published.
🧊1😂6
is a tailing factor of anything specific a problem
shallow gradients hide related substances behind the main peak. a steeper one separates and looks worse, honestly
baseline drift on a gradient is normal. baseline drift on an isocratic hold is your column, from memory
integration difference
coming back to this how do you tell co-elution from a clean single peak
i have a number at about a third of what i expected, is that a charge state