a certificate with a number and no chromatogram is asking you to trust the integration you cannot see
#hplc-massspec 2026-04-22
Wednesday13 messages5 participantstimes are UTC
Highlights from this day
- VialBot — Inter-lab diff for lot A-2418: 98.6% vs 98.1%. Within expected range. 13:25
- blank_run — relative retention time against a standard is comparable between labs. absolute minutes are not 13:26
- monoisotopic — the honest position is that hobby-level interpretation of a chromatogram is worth something but not much 14:10
within inter-lab range
plus 16 is oxidation
if the lab reports area percent without stating the wavelength, the number is less useful than it looks
a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you, i have it written down somewhere
why do two labs integrate the same peak differently
tirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5
Inter-lab diff for lot A-2418: 98.6% vs 98.1%. Within expected range.
📉10🧪3
relative retention time against a standard is comparable between labs. absolute minutes are not
👍14🧊4
why does integration change the number so much
the honest position is that hobby-level interpretation of a chromatogram is worth something but not much
👀16📉1
show me the spectrum
i have a number at about a third of what i expected, is that a charge state
🧪1