Quality Control
Endotoxin
Research use only. For in vitro research use only. Not for human or animal consumption. Not for human consumption, medical use, or personal application.
Endotoxin is lipopolysaccharide from the outer membrane of Gram-negative bacteria. It matters because it outlasts the organism that made it: heat-stable, not retained by the filters that remove whole cells, and still active in cell-based systems after sterilisation. Where a lot has been assessed, the result is given in endotoxin units per milligram or millilitre.
Why sterilisation does not settle the question
Filtration and heat address viable cells. Lipopolysaccharide is a molecular fragment, far smaller than a cell and stable at temperatures that destroy one, so it passes a 0.2 µm filter and survives autoclaving.
Removal means depyrogenation — sustained dry heat for glassware, adsorptive steps for solutions. A sterility statement and an endotoxin figure answer different questions about one vial, and neither implies the other.
The contribution rarely comes from the peptide
Water, glassware, stoppers, tips and diluent all feed in, which is why cell-culture procedures specify endotoxin-controlled water and not merely a controlled solute. The choice of sterile water is part of that control.
If an endpoint is sensitive, set the limit in your own specification before ordering and check the lot's Certificate of Analysis against it. Where the attribute is unreported, the options are in-house testing or another source, and reconstitution practice decides how much control sits with the laboratory.
Frequently asked questions
- Does a low result on one lot apply to the next?
No. Endotoxin is a lot attribute and varies between production runs under an unchanged process. Match the figure to the lot number on the vial, as the batch verification guide sets out.
- Can endotoxin be removed from a reconstituted peptide?
Not conveniently. Ordinary filtration does not retain lipopolysaccharide, and depyrogenation is not compatible with peptide already in solution. Control sits with the water, glassware and technique instead.
- What does EU/mg mean on a certificate?
Endotoxin units per milligram of material. The unit is referenced to a reagent system's response against a standard preparation rather than to a mass, so convert it to your working concentration.
Updated 2026-06-01