Chromogenic (colour) method. LAL agent has an appropriate synthetic substrate, producing yellow colour after the reaction with endotoxin-activated protein. The test is read in a microplate reader at 405 nm wavelength. It can be performed using the final result or kinetic method. Maximum sensitivity – 0.001 EV/ml.
Turbidimetric (turbidity) method. Kinetic method, based on the appearance of turbidity, by treating lysate with endotoxin. Turbidity optical density is measured with incubating microplate reader or incubating tube reader. Test sensitivity – 0.001 EV/ml.
Gel-clot (gel lump) method. LAL agent affected by endotoxin forms gels. This is the simplest method. Results are evaluated by inverting the tube. Maximum sensitivity – 0.03 EV/ml. It is the cheapest method as it does not require an optical scanner. It is suitable for opaque and coloured samples of suspensions.