For research use only. Not for human consumption, diagnostic or therapeutic use.

Karl Fischer titration, and what water content tells you about a lot

Residual moisture affects both stated mass and long-term stability. How the measurement is made and what a normal range looks like.

Reading an HPLC chromatogram on a certificate of analysis

A lot can be 98% pure by HPLC and still contain substantially less peptide by mass. Water, counterion and residual solvent all sit in the gap.