#hplc-massspec 2026-01-29

update on the earlier thing how do you spot a deletion in a sequence from mass alone

the first peak is the solvent. it is always the solvent

show me the spectrum

integration difference

a warm transit can put a visible degradant peak on a chromatogram. that is what 5 days at ambient does, we shall see

plus 0.98 is deamidation

i asked Medutest for the raw trace and they sent it. that is the right answer to that question

update from 4 months ago: switched to asking for the chromatogram rather than the number and it changed everything

while im here a shoulder on a peak is information, and usually bad information

co-elution is the failure mode that a beautiful single peak is most likely to be hiding

does retention time on its own tell you what the compound is

214nm sees the amide backbone so it sees everything. 280 only sees aromatics

my peak has a shoulder on it, what does that usually mean

nobody runs enough blanks, including me

does ms/ms actually prove identity or just make it very likely

for the archive you need more sample for identity than for purity. plan for that when you post it

relative retention time against a standard is comparable between labs. absolute minutes are not, i think