Abstract: An indirect agglutination immunoassay includes the steps of providing, in a container, an immunoassay system comprising a test sample containing a desired analyte, and a reagent composed of magnetic particles or magnetic-material containing particles containing iron therein, wherein the magnetic particles or magnetic-material containing particles have been sensitized to allow specific binding to the desired analyte, and have a particle size in the range of 1 to 5 &mgr;m, with the content of the iron being in the range of 8 to 20 wt. %, precipitating the magnetic particles or magnetic-material containing particles by the application of magnetic force, allowing the container to stand at an inclination, and detecting the presence or absence of an immune reaction from the absence or presence of slippage observed of the precipitated magnetic particles or magnetic-material containing particles on the bottom of the container.

Abstract: An apparatus for judging an agglutination has a transparent plate stand 5 for supporting a microplate 7 and perforated with positioning openings 9 for centering of each well 8 of the microplate. A light source and TV camera 12 are disposed above the microplate, an image memory 13 stores the output of the camera, a processor 15 differentiates the stored image to determine its profile, and the picture elements of the differentiated image having intensity levels larger than zero are counted. A calculator 17 produces coefficients of variation, which are plotted against the image profile and compared with a reference value to remove contrast irregularities.

Abstract: A continuous tritium radioactivity measuring system is disclosed, in which a sample gas containing tritium is mixed with hydrogen gas, water vapor and lower hydrocarbon gases with the assistance of a catalyst for causing an isotope exchange reaction between the tritium contained in the sample gas and hydrogen. The resultant tritium gas and lower hydrocarbons containing tritium are removed from the remaining hydrogen water, and radioactivity detection is performed thereon.

Abstract: A sample material to be dehydrated is enclosed in a container transmissive to microwave and air is past through the container under a microwave radiation to preferentially remove the water content of the sample. The dehydrated sample may be incinerated by switching the air supply to an oxygen supply under the microwave radiation.

Abstract: A first and a second radioactivity detectors are used in series or in parallel which have substantially the same constructive features and the second radioactivity detector includes a fixed standard radioactive source therein. Sample gases each having a common radioactivity and having a different quenching effect are passed through the two radioactivity detectors sequentially to measure the effective radioactivities thereof to thereby obtain counting efficiencies of the two radioactivity detectors. A correction curve is drawn by putting the counting efficiency of the first radioactive detector along one axis of an orthogonal coordinates and the counting efficiency of the second radioactivity detector along the other axis of the coordinates.

Abstract: An air sample including substances containing tritium and substances containing carbon-14 is oxidized continuously while measuring a volume thereof and water and carbon dioxide included in the oxidized air sample are collected respectively continuously. After water and carbon dioxide are recovered, the radioactivities thereof are measured respectively.