#hplc-massspec 2025-03-02

Sunday11 messages4 participantstimes are UTC

Highlights from this day

HPLC_Hank — a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you 14:17
HPLC_Hank — deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant 14:20
salt_bridge — integration choices move the number by a few tenths easily. that is most of your inter-lab variance 14:23
ten_of_ten — truncations show as a mass deficit matching one or more residues. you need the sequence to say which 14:28
void_volume — how much sample does a lab actually need for identity as well as purity 14:30

a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you

📉9🧪1

deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant

✅1🙏16💀2

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

integration choices move the number by a few tenths easily. that is most of your inter-lab variance

baseline drift on a gradient is normal. baseline drift on an isocratic hold is your column

ask for the trace

genuine question you need more sample for identity than for purity. plan for that when you post it

truncations show as a mass deficit matching one or more residues. you need the sequence to say which

thats co-elution

how much sample does a lab actually need for identity as well as purity

👀17✅3

a shoulder on a peak is information, and usually bad information