Method and nephelometer for determining the quantity of an antigen in a specimen

摘要

A specific quantity of a specimen is mixed with a given quantity of an antibody material in order to form immunochemical complex particles in a test tube (24). The test tube with the mixture is placed into a chamber (15) surrounded by a light-tight housing (12) in such a way that the longitudinal axis of the test tube extends vertically. A laser beam (14) produced by a laser (13) is directed through an opening (28, 29) in the housing at right angles to the longitudinal axis of the test tube onto the mixture contained therein. A portion of the scattered light passes via a light-measuring channel (32) extending at an angle of 45 DEG to the longitudinal axis of the test tube to a photodetector (36) for generating an output signal as a function of the flux of scattered light. In order to prevent the light scattered at the wall of the test tube from passing into the light-measuring channel, stops (33, 34) are provided which allow only scattered light originating from the interior of the test tube to pass to the photodetector. The non-scattered portion of the laser beam is virtually completely absorbed in a recess (31) lined with light-absorbing material. <IMAGE>