What Is Endotoxin Testing?
Bacterial endotoxin testing measures lipopolysaccharide derived from the outer membrane of Gram-negative bacteria. It is typically performed using LAL or recombinant Factor C methods and reported in endotoxin units (EU) per milligram or per vial. Endotoxin content is independent of chemical purity.
Published 2026-08-22 · Updated 2026-08-22 · Reviewed by the Lana editorial team
Why is endotoxin measured separately?
Endotoxin is not a peptide-related impurity and will not appear as a chromatographic peak in a standard HPLC purity assay. It requires a dedicated biological or recombinant assay.
How are results expressed?
Results are given in endotoxin units per milligram of material or per container, alongside the method used and the detection limit of the assay.
What endotoxin testing does not establish
A low endotoxin figure does not establish sterility, chemical purity, or identity of the peptide.