Method for measuring target substances, and reagents thereof.

Abstract

This invention provides a method and reagents for measuring low concentrations of target substances using immunoturbidimetry. [Solution] A measurement method for measuring a target substance contained in a sample, wherein the target substance is a protein with a molecular weight of 150 kDa to 500 kDa, contained in the sample at a concentration of 0.8 ng / mL to 2.0 ng / mL, and comprises: a first mixing step of mixing the sample with a first reagent to obtain a first mixed solution; a second mixing step of mixing the first mixed solution with a second reagent containing particles immobilized with ligands that specifically bind to the target substance to obtain a second mixed solution; and a measurement step of measuring the absorbance of the second mixed solution, wherein the concentration of the sample in the second mixed solution is 4.0 volume% to 30.0 volume%, the mass ratio of particles to sample in the second mixed solution is 1:500 to 1:50, and the change in absorbance per 1.0 ng / mL of target substance in the measurement step is 0.0012 to less than 0.0100 for the sample.

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