Endotoxin is the lipopolysaccharide (LPS) complex located in the outer membrane of gram-negative bacteria. During experimental procedures, large amount of endotoxins are shed and can easily contaminate labware, buffers and downstream products. Presence of endotoxin in any of these has a detrimental effect on culturing of cells and can lead to generation of irreproducible or negative experimental data. Therefore, it is critical to keep endotoxin away from samples and products. Endotoxin-free Water is recommended to use for samples with special requirement of endotoxin level (< 0.05 EU/ml).