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What the data says about a peptide
We take chromatograms, mass spectra and certificates of analysis one at a time and show how we read them. A new note every morning.
03.10.2026Analytical methods5 min
Why 99% HPLC purity is not 99% peptide in the vial
TFA and acetate counter-ions, residual water and the gap between HPLC purity and net peptide content, with a simple calculation on molar masses.
Open the note02.10.2026Certificates
What a certificate of analysis contains for a peptide batch
The lines we look for on a peptide CoA: batch, method, HPLC purity, confirmed mass, appearance, date. And the signs that the document is a generic one.
01.10.2026Analytical methods
How we read an HPLC chromatogram of a peptide
The axes, the main peak, retention time, the small peaks beside it and how purity is worked out from peak areas. And what a chromatogram cannot tell us.