Related Experiment Video
Updated: Jun 8, 2026

Endotoxin Activity Assay for the Detection of Whole Blood Endotoxemia in Critically Ill Patients
Published on: June 24, 2019
Saline and buffers minimize the action of interfering factors in the bacterial endotoxins test
Yuu Fujita1, Tetsuhiro Tokunaga, Hirofumi Kataoka
1Biological Research Department, Sawai Pharmaceutical Co., Ltd, Miyahara 5-2-30, Yodogawa-ku, Osaka 532-0003, Japan. y.fujita@sawai.co.jp
Abstract:
The bacterial endotoxins test (BET) is the most sensitive assay for measuring endotoxin levels in solution. However, it is difficult to quantify endotoxin levels in some solutions because unknown interfering factors may inhibit or enhance the Limulus amebocyte lysate (LAL) coagulation reaction. We investigated the mechanisms of this interference and found that interference can be reduced or totally suppressed by preparing sample solutions in saline, Dulbecco's phosphate-buffered saline (D-PBS), N,N-bis-(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES), or 2-amino-2-hydroxymethyl-1,3-propanediol (Tris) buffers. We examined the inhibitory effect on the interfering action of various reagents. The reagents examined were classified into two groups: a weak interference and a strong interference group. The interference of the strong interference group was suppressed by adding endotoxin and the test factors to LAL individually. Endotoxin peaks analyzed by gel-filtration HPLC disappeared in the presence of interfering factors. When buffers were used to prepare sample solutions instead of water, endotoxin peaks were maintained and interference with LAL reaction was suppressed. These results indicate that for the strong interference group, interference of the LAL reaction was a direct consequence of interfering factors binding to endotoxin. This alters endotoxin complexation, but this effect may be suppressed by preparing solutions in saline or other buffers instead of in water.
Related Concept Videos
Buffer Effectiveness
The buffer capacity is the amount of acid or base that can be added to a given volume...
Buffers
Bacterial Toxins
Biological Methods for Microbial Control
Inhibitors of Bacterial Protein Synthesis
Inhibitors of Gram-positive Cell Wall Synthesis
