An endotoxin-sensitive enzyme found in horseshoe crab blood has been used to test Lipopolysaccharides in pharmaceutical products since 1983. To move to a more sustainable method for Lipopolysaccharides testing, a recombinant protein, Recombinant Horseshoe Crab Factor C (rFC), was developed. rFC provides a consistent, secure and environmentally sustainable method for endotoxin testing.