NEPHELOMETER HAVING MEANS SEMIAUTOMATICALLY CANCELLING COMPONENTS FROM SCATTERING BY PARTICLES SMALLER OR LARGER THOSE OF INTEREST

摘要

An improved nephelometer for immunochemical complex assay measures forward light scatter in samples. The angle of forward scatter, about 30.degree., is small enough to result in a large amount of forward scatter from the immunochemical complex particles which are to be assayed, whose size is of the order of the wave length of the light used in the optical system. Forward scattering from smaller particles, such as from molecules of buffer, antibody and serum, is constant during the course of a test, and is compensated for by the use of subtraction circuits which are readily and semiautomatically adjusted to subtract proper values, in accordance with the readings taken on standard or "blank" samples of buffer, antibody and serum. Forward scattering from large particles, such as dust, is variable, and results in fluctuating signals, which are electrically processed to ignore the spurious peaks. The results of a test are displayed on a digital read out meter. Also described is a method of and protocol for immunochemical assay, whereby the amount of antigen originally present in a sample is determined by adding a known amount of antibody, and by assaying the "blank" component ingredients and the resulting mixture.