Quantitative endotoxin determination in blood with a chromogenic substrate.

A method is described for the quantitative determination of endotoxins in blood. The method is based upon the endotoxin-dependent activation of a proenzyme present in Limulus amebocyte lysate. This activated enzyme is measured by using the chromogenic substrate S 2422. Inhibitors and activated coagulation factors possibly interfering in the assay are removed by dilution and boiling. The method has been proven to be fast (2.5 h), sensitive and reproducible with a detection limit of 10 ng/l. Preliminary results comparing the results of blood cultures with the endotoxin assay indicate a good correlation.