Mix a sample with LAL reagent in a test tube and incubate it using a block heater at 37 ± 1 °C, 60 ± 2 minutes, without subjecting to vibration. Upon completion of heating, immediately but slowly tilt the tube through 180°. If a gel has formed and maintains its integrity without deformation or collapse, the result can be determined positive, while it is negative if no gel has formed. During the test, a series of samples is diluted multiple times (usually 2-fold) to check if the result is positive in each sample. The maximum valid dilution or the minimum
concentration determined positive is referred to as the endpoint.
Invert the tube through about 180˚.
(Turn the tube upside down.)
This technique uses synthetic chromogenic substrate cleavage to detect the activation of LAL reagent induced by endotoxin.
This technique uses the change in gel turbidity to detect the activation of LAL reagent induced by endotoxin.