The importance of the quality of water in Limulus Amebocyte Lysate tests

Commercial pharmaceutical waters were evaluated regarding their interference in the chromogenic Limulus Amebocyte Lysate (LAL) test. Two of the four tested waters strongly inhibited the U.S. Reference Standard Endotoxin, while a Control Standard Endotoxin was less affected. The inhibitory effect could be mimiced by adding trace amounts of certain metal ions to a non-interfering water. In conclusion, the water used in the LAL test must be chosen with great care.