Limulus Amebocyte Lysate (LAL) is a biological reagent prepared from the lysate of amebocytes extracted from the blue blood of horseshoe crabs, marine arthropods. It is prepared by low-temperature freeze-drying and is used for the qualitative or quantitative detection of bacterial endotoxins and (1,3)-β-D-glucans in various samples.

These samples include pharmaceuticals, medical devices, animal and human body fluids such as blood and urine, food products, water sources, and other biological or environmental samples.