A turbidimetric-kinetic photometer which monitors 64 samples simultaneously and independently has been developed for the automated measurement of endotoxin. This instrument measures the turbidity change at 660 nm in a gelation reaction of the LAL/endotoxin system and automatically scores the reaction time required to obtain a certain turbidity change as gelation time. Since a stationary dry bath incubator controls the reaction temperature of the samples at 37 ± 0.5°C and also controls the ambience of the optical system assembled into the incubator, the objective detection of gelation is provided without any disturbance from sample vibration, and the drift of the detection system is minimized. An extremely wide range for the calibration curve, such as 4 or 5 orders of magnitude of endotoxin concentration, is obtained without sample dilution. The coefficients of variation of the calculated endotoxin concentration are 4.91 to 14.0%.
Haruki Oishi, Yasumichi Hatayama, Masaji Fusamoto, and Yoshitsugu Sakata, "Development of a Multichannel Turbidimetric-Kinetic Photometer for the Quantitative Determination of Endotoxin," Appl. Spectrosc. 43, 821-826 (1989)