What Greater Than 99% Purity Means

A reported HPLC or UPLC area percentage depends on the column, mobile phase, gradient, wavelength or detector, integration rules, system suitability, and reporting threshold. Results generated under different methods may not be directly comparable.

A large main peak does not, by itself, prove correct molecular identity or sequence, net peptide content, potency, sterility, bacterial-endotoxin status, fill quantity, or stability after shipping. Those are separate analytical or process questions.

A useful purity claim is tied to the tested material and accompanied by the method, chromatogram, integration and system-suitability information, result and units, and complementary identity testing. The specification and the result should be visibly distinct.