Bridge Labs
Bacterial endotoxins are fragments of the outer membrane of Gram-negative bacteria (lipopolysaccharides). They persist long after the bacteria are gone and are not removed by ordinary sterilisation. For any material intended to be injected, the endotoxin load is a distinct quality question that sterility alone does not answer.
Why it matters
Endotoxins are pyrogenic: in the bloodstream they can trigger a strong immune response. Even a sterile preparation can retain residual endotoxin, so it is treated as a separate parameter for parenteral material. This page is general information about the test, not medical or safety advice.
What is reported
Results are expressed in endotoxin units (EU) — typically EU/mL for a solution and EU/mg normalised to mass. Reporting a number, rather than only “below limit”, lets the value be compared against the limit appropriate for the intended quantity and route. The method, dilution and control behaviour are reported alongside it.
Common methods
Kinetic chromogenic measures the reaction continuously against a calibration curve and yields a quantitative figure. Gel-clot is the classical format, often used as a confirmatory or limit test. Where a sample interferes with the reaction, the dilution is adjusted so the figure reflects true endotoxin content.
To arrange testing, see submit a sample.