Gel clot method

A bacterial endotoxin test method in which endotoxin causes Limulus amebocyte lysate to form a firm gel. Sample and lysate are mixed in tubes and incubated undisturbed at 37 °C for 60 minutes. The tube is then inverted 180°: a firm gel that stays intact is positive, while no gel or a broken gel is negative. It is simple and robust, and is the referee method when results from different BET methods disagree.