A sensitive chromogenic Limulus amoebocyte lysate micro-assay for detection of endotoxin in human plasma and in water.

This chromogenic endotoxin assay involves a 45 min incubation of plasma extract or water with a mixture of Limulus amoebocyte lysate and the chromogenic substrate S-2423. Absorbance is measured in micro-titre plates. The assay allows the detection of 0.2 pg endotoxin per ml in water (0.002 Endotoxin Units/ml) and 1 pg endotoxin per ml in plasma (0.012 Endotoxin Units/ml). The intra-assay coefficient of variation is less than 5%.