#hplc-massspec 2026-05-16

Saturday16 messages4 participantstimes are UTC

Highlights from this day

verify_or_dont — baseline drift on a gradient is normal. baseline drift on an isocratic hold is your column, from memory 16:55
verify_or_dont — if the lab reports area percent without stating the wavelength, the number is less useful than it looks 16:56
verify_or_dont — the honest position is that hobby-level interpretation of a chromatogram is worth something but not much, i think 17:09
verify_or_dont — two labs a point or two apart on the same lot is normal and gets mistaken for one of them being wrong constantly 17:10
verify_or_dont — slightly off topic but my peak has a shoulder on it, what does that usually mean 17:50

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

if the lab reports area percent without stating the wavelength, the number is less useful than it looks

coming back to this whats a plus one dalton shift usually

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

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

need more sample

🔥18😂8

the honest position is that hobby-level interpretation of a chromatogram is worth something but not much, i think

two labs a point or two apart on the same lot is normal and gets mistaken for one of them being wrong constantly

👍12🎉2

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

whats the void volume peak, is that always solvent

how do you spot a deletion in a sequence from mass alone

quick one why do two labs integrate the same peak differently

monoisotopic and average diverge more the bigger the molecule. say which one you are quoting

slightly off topic but my peak has a shoulder on it, what does that usually mean

🤝3

i have a number at about a third of what i expected, is that a charge state

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