Glossary
Endotoxin
A heat-stable lipopolysaccharide from the outer membrane of Gram-negative bacteria, screened for because it is not removed by sterilisation.
Endotoxins are lipopolysaccharide fragments shed by Gram-negative bacteria. They are relevant to laboratory materials because they survive autoclaving and sterile filtration removes bacteria but not necessarily the endotoxin they leave behind, so a material can be sterile yet still carry endotoxin. Endotoxin content is measured by the LAL test and reported in endotoxin units (EU). Screening for it is a quality parameter for laboratory materials, reported on some certificates of analysis.
Covered in depth in Peptide laboratory testing methods.
Related terms
- LAL test
- The Limulus amebocyte lysate assay, a test that detects and quantifies bacterial endotoxin.
- Sterile filtration
- Passing a solution through a 0.22-micron filter to remove bacteria, a sterilisation step that does not remove endotoxin.
- Aseptic technique
- A set of laboratory handling practices that keep a sterile material free of microbial contamination while it is worked with.