Endotoxin

Endotoxins are bacterial-membrane components that can contaminate biological products. Endotoxin screening on a COA confirms a compound meets purity thresholds for research use.

Endotoxins are lipopolysaccharide (LPS) molecules from the outer membrane of Gram-negative bacteria. They are heat-stable and are not eliminated by routine sterilization, so they can persist in a product even after it has been sterile-filtered, which is why they are screened separately on a certificate of analysis.

Endotoxin content is quantified by the Limulus amebocyte lysate (LAL) assay and reported in endotoxin units per milligram or milliliter. Low levels matter in cell-based research because LPS is a potent activator of Toll-like receptor 4 (TLR4) and can trigger inflammatory signaling that confounds experimental results.