Purity is a relative chromatographic result
A reported HPLC area percentage is tied to sample preparation, column, mobile phase, gradient, wavelength, integration and which peaks the method can see. It is not a universal mass balance.
Content is an amount question
Lyophilized material can include peptide, water, counter-ions and other justified components. The buyer should ask whether the labeled fill refers to gross powder, net peptide, an assay-corrected amount or another defined basis.
- State the labeled amount basis
- Request water result where relevant
- Identify salt or counter-ion form
- Agree the content method and uncertainty
Build a method set around the decision
Supplier qualification, identity confirmation, formulation work and sensitive biological assays do not always need the same panel. Write the purchase specification from the research risk, then request the matching evidence.