Endotoxin (LAL) Testing for Research Peptides
Endotoxin is bacterial lipopolysaccharide (LPS) that survives sterilization and can distort in-vitro and in-vivo research even in trace amounts. Any peptide destined for cell culture or animal-model work should ship with a documented endotoxin result — not just a purity number.
What is endotoxin?
Endotoxin is a component of Gram-negative bacterial cell walls. It's heat-stable, survives autoclaving, and triggers immune response at picogram-per-milliliter levels — enough to invalidate a cell-culture experiment.
How LAL testing works
The Limulus Amebocyte Lysate (LAL) assay uses a clotting reaction from horseshoe-crab blood cells that is exquisitely sensitive to endotoxin. Modern variants (kinetic chromogenic, recombinant Factor C) quantify endotoxin in endotoxin units per milliliter (EU/mL) which is converted to EU/mg based on peptide concentration.
What thresholds are acceptable?
For general research use: <10 EU/mg is standard. For cell culture: <1 EU/mg. For in-vivo animal research: much lower — often <0.1 EU/mg. Ask your supplier what threshold their COA reports against.
PX1's endotoxin documentation
Every PX1 batch ships with LAL endotoxin data on the COA. Representative reports are published on our /endotoxin-reports page.
Frequently Asked Questions
Do research peptides need endotoxin testing?
Yes for any peptide used in cell culture or in-vivo research. LPS contamination can invalidate results at picogram-per-milliliter levels.
What endotoxin threshold is safe for cell culture?
Generally <1 EU/mg for cell culture and <0.1 EU/mg for sensitive in-vivo work.
Related pages
All products are sold strictly for laboratory and research use only. Not for human or veterinary use, diagnosis, treatment or consumption. Statements have not been evaluated by the FDA.