λc= 1g- 1(∑X/4)

Where x is the logarithmic value of the concentration at the end of the reaction (1g). The end-point concentration of reaction refers to the concentration of the last positive result in a series of endotoxin concentration decreases.

Extended data

The study of limulus test can be traced back to 1980s, but the actual medical value of limulus blood was discovered only after F.Bang, a zoologist at Johns Hopkins University, published a paper entitled "A bacterial disease of limulus" in 1956.

The main component of limulus lysate reagent is to remove anti-lipopolysaccharide factor by chloroform treatment, and add appropriate amount of divalent calcium and magnesium ions, which contain factors C, B and G.

Therefore, scientists believe that horseshoe crab with light blue blood plays a unique role in medical research. The reagent is made of limulus blood and then dripped into the injection. If the reagent solidifies or discolors immediately, it means that the injection contains bacterial endotoxin which can cause fever, shock and even death.