Abstract: A method used to detect endotoxin uses a system (10) having bidirectional pump (20), multiport valve (30), fluid section valve (170), fluid holding member (50), solenoid valve (60), air source (63) and detector (100). Sample, LAL reagent and chromogenic substrate fluid segments are introduced into the holding member (50) between air segments, the reagents are then mixed and introduced into the detector (100) for measurement The system can be washed with an alkaline solution and followed by cthanol, or washed with tricthylaminc followed by water.