Automation and computerization of chromogenic LAL assay method for bacterial endotoxin using 96-well microtiter plate

A high degree of automation was achieved for a chromogenic substrate Limulus amebocyte lysate (LAL) assay method for bacterial endotoxin using a Cetus Pro/Group Liquid Handler and 96-well microtiter plates. A Titertek Multiskan Reader was interfaced with an IBM PC using a LOTUS MEASURE software to capture optical density values of samples in a LOTUS 1-2-3 spreadsheet. A password protected, menu-driven macro programmed in LOTUS 1-2-3 automates the calculation, evaluation of assay parameters, documentation, and generation of a formatted three-page report suitable as a primary record. All assay operations, including testing 19 samples against a four-point standard curve in replicates of four each, the calculation of results, and generation of a report, are completed in less than 40 minutes. The relative standard deviation (RSD) of the assay is approximately 7%, which compares favorably with the robot automated system.