Limulus amoebocyte lysate assay of endotoxin: a method for visual detection of the positive gel reaction

In a Limulus amoebocyte lysate micro-test system, visual differentiation between positive and negative reactions was obtained by the addition of a small drop of fresh, defibrinated sheep blood to the reaction mixture. This method has greatly facilitated end-point identification in a series of dilutions of endotoxin.