you need more sample for identity than for purity. plan for that when you post it
#hplc-massspec 2026-06-04
Thursday18 messages4 participantstimes are UTC
Highlights from this day
- no_appetite_nia — why does integration change the number so much 17:46
- sedge_sources — if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic 17:57
- gus_charts — retention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily, thats just me 18:23
- salt_bridge — plus sixteen, is that always oxidation 18:24
i have a number at about a third of what i expected, is that a charge state
thats a charge state
why does integration change the number so much
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need more sample
relative retention time against a standard is comparable between labs. absolute minutes are not, anyway
show me the spectrum
coming back to this baseline is drifting badly, is that the column or the mobile phase
*VendorInvestigate not the other one
no_appetite_niacoming back to this baseline is drifting badly, is that the column or the mobile phase
if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic
if somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result
a warm transit can put a visible degradant peak on a chromatogram. that is what 7 days at ambient does
if the lab reports area percent without stating the wavelength, the number is less useful than it looks
oxidation is about plus 15.99 Da and is usually methionine or tryptophan, ill dig out the number
[edited]deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant
do the arithmetic
retention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily, thats just me
plus sixteen, is that always oxidation
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