follow up i have had a lot where the mass was exactly right and the purity was 96.8. wrong question, right answer
#hplc-massspec 2026-01-09
Friday12 messages4 participantstimes are UTC
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- tail_factor — follow up i have had a lot where the mass was exactly right and the purity was 96.8. wrong question, right answer 20:42
- tail_factor — truncations show as a mass deficit matching one or more residues. you need the sequence to say which 20:43
- back_from_away — a certificate with a number and no chromatogram is asking you to trust the integration you cannot see 21:21
- back_from_away — does ms/ms actually prove identity or just make it very likely 214nm sees the amide backbone so it sees everything. 280 only sees aromatics 21:32
- back_from_away — deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant 21:55
truncations show as a mass deficit matching one or more residues. you need the sequence to say which
coming back to this do you trust an area percent from a shallow gradient
plus 0.98 is deamidation
🎉2👍2
plus 16 is oxidation
a certificate with a number and no chromatogram is asking you to trust the integration you cannot see
why does integration change the number so much
does ms/ms actually prove identity or just make it very likely
214nm sees the amide backbone so it sees everything. 280 only sees aromatics
thats a charge state
how do you spot a deletion in a sequence from mass alone
deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant
is a tailing factor of anything specific a problem