Haruki Oishi

Development of a Multichannel Turbidimetric-Kinetic Photometer for the Quantitative Determination of Endotoxin

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%.

Development of a multifunctional laser nephelometer using backward light scattering detection for clinical diagnosis of blood coagulation and fibrinolysis

Abstract A multi-functional laser nephelometer which detects backward light scattering has been developed for the clinical diagnosis of blood coagulation and fibrinolysis. This instrument measures the turbidity change at 790 nm in a blood coagulation reaction, an antigen-antibody reaction, or a latex agglutination reaction. In a blood coagulation reaction, the time required to detect the maximum rate of the turbidity change is measured as the coagulation time, from which the biological activity of the blood coagulation is automatically determined. Both in an antigen-antibody reaction and in a latex agglutination reaction, the maximum rate of the turbidity change is measured, from which the immunological activity of the target antigen is again automatically determined. The detection of backward light scattering, the optimization of electronic detection sensitivity, and the software switch of the differentiation parameters depending on the reaction rate of a respective item, make it possible to measure these three kinds of reactions with a common instrument. This method also reduces the measuring time of the immunological reaction compared with that of conventional endpoint methods. The coefficients of variation of the activity determined over each tested item are 0.583 to 5.03%. The correlation coefficients of the determined activity with conventional methods are as good as 0.968 to 1.000.