Coagulogen-free clarified limulus amebocyte lysate

A composition comprising clarified limulus amebocyte lysate (LAL) and a detergent, wherein the clarified LAL comprises less than 5% (wt/wt) of coagulogen relative to total protein in the LAL as measured by SDS-PAGE and protein stain, and wherein the clarified LAL is made by a method comprising:

• a. obtaining a solution derived from lysed amebocytes from Limulus polyphemus;
• b. combining the solution from (a) with a buffer;
• c. subjecting the combination from (b) to continuous tangential flow filtration (TFF) using a 20 kDa to 50 kDa membrane filter to produce a retentate;
• and
• d. centrifuging the retentate from (c) at greater than 20,000×g for greater than 25 minutes to produce a supernatant, wherein the supernatant is the clarified LAL.

A kit comprising:

• a. a composition comprising clarified limulus amebocyte lysate (LAL) and a detergent, wherein the clarified LAL has been (i) filtered using tangential flow filtration with a 20 kDa to 50 kDa filter to remove at least 60% (wt/wt) of its coagulogen such that it comprises less than 10% (wt/wt) of coagulogen relative to total protein in the LAL as measured by SDS-PAGE and protein stain, and then (ii) subjected to centrifugation,
• b. a chromogenic substrate;
• and
• c. instructions for detecting an endotoxin using the composition and the chromogenic substrate.